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This article discusses the possibilities of estimation of safe sizes of integrity defects on the basis of risk criteria. Such defects occur at all stages of the lifetime of structures. In most cases the estimation of their hazard and determination of allowable sizes attract attention when the defects can lead to brittle or quasi-brittle fractures. In this case, the models of linear and nonlinear destruction mechanics are applied, when the defects are considered as internal elliptical or surface semielliptical cracks. The stochastic variety of shapes, sizes, locations, and orientations of defects has a significant influence on the failure mechanisms. Therefore, the probabilistic problem of estimating allowable sizes of defects according to the criteria of risk of failure is relevant. This paper examines a general approach to estimation of the hazards of defects according to risk criteria. Two formulations of the probabilistic problem of risk estimation are presented: on the basis of single-parameter and two-parameter failure criteria. The risk function is used as the calculated characteristic, represented as the probability of failure according to a given criterion. An equation of the risk function based on single-parameter failure criteria is presented. The main focus is on the probabilistic model based on the two-parameter Morozov failure criterion. This criterion provides a wide range of opportunities for analyzing various failure mechanisms with variations in the size of defects. An expression for the risk function based on the family of two-dimensional Lu–Bhattacharya probability distributions of Weibull type is derived. It is shown that correlations between failure mechanisms can significantly influence the probabilities of failure and, consequently, the allowable size of defects. [ABSTRACT FROM AUTHOR]

Multi‐fidelity models are of great importance due to their capability of fusing information coming from different numerical simulations, surrogates, and sensors. We focus on the approximation of high‐dimensional scalar functions with low intrinsic dimensionality. By introducing a low dimensional bias we can fight the curse of dimensionality affecting these quantities of interest, especially for many‐query applications. We seek a gradient‐based reduction of the parameter space through linear active subspaces or a nonlinear transformation of the input space. Then we build a low‐fidelity response surface based on such reduction, thus enabling nonlinear autoregressive multi‐fidelity Gaussian process regression without the need of running new simulations with simplified physical models. This has a great potential in the data scarcity regime affecting many engineering applications. In this work we present a new multi‐fidelity approach that involves active subspaces and the nonlinear level‐set learning method, starting from the preliminary analysis previously conducted (Romor F, Tezzele M, Rozza G. Proceedings in Applied Mathematics & Mechanics. Wiley Online Library; 2021). The proposed framework is tested on two high‐dimensional benchmark functions, and on a more complex car aerodynamics problem. We show how a low intrinsic dimensionality bias can increase the accuracy of Gaussian process response surfaces. [ABSTRACT FROM AUTHOR]

A description of a small icing wind tunnel designed for studying the icing processes at the Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences is presented. The use of such a wind tunnel offers a possibility not only of studying the physical features of the icing process, but also of testing methods of anti-icing control, validating numerical methods used for calculating the icing processes, etc. [ABSTRACT FROM AUTHOR]

The corresponding author had the pleasure of attending an excellent symposium titled "Experimental and Theoretical Micro- and Nano-Mechanics: Honoring the Contributions of Prof. Kyung-Suk Kim" organized by Professors Ashraf Bastawros, Wendy Crone, Yanfei Gao, and Ruike (Renee) Zhao as part of the 2022 Society of Engineering Sciences Annual Technical Meeting held in College Station, TX on October 16-19, 2022. The symposium was held in honor of Prof. Kim's 70th Birthday and celebrated over 40 years of Prof. Kim's independent research achievements across several areas of Applied Mechanics. The present paper is dedicated to Prof. Kim, a great colleague at Brown University. We present a new formulation for the multilayer isogeometric Kirchhoff-Love (KL) shells, where the individual layers are assumed to interact through no-penetration and frictional contact. This work is largely motivated by the experiments and analysis presented in Poincloux et al. (2021, "Bending Response of a Book With Internal Friction," Phys. Rev. Lett., 126(21), p. 218004). We utilize a regularized version of Coulomb's friction law to model the tangential traction between the contacting shell surfaces. To ensure objectivity (i.e., reference-frame invariance) in the frictional model, we propose two different strategies to extrapolate the velocity vectors of the contact pair at the contact interface: (i) using the underlying KL kinematics of the individual shell layers and (ii) using the Taylor series-based extension from Kamensky et al. (2019, "Peridynamic Modeling of Frictional Contact," J. Peridyn. Nonlocal Model., 1(2), pp. 107-121). We compare the performance of both approaches through a numerical benchmark example. We then validate our multilayer shell formulation using the "bending response of a book with internal friction" experiments of Poincloux et al. (2021, "Bending Response of a Book With Internal Friction," Phys. Rev. Lett., 126(21), p. 218004). [ABSTRACT FROM AUTHOR]

Stephen Timoshenko was the author of numerous textbooks on various aspects of applied mechanics, and through them contributed to its rapid development in the world. As always, the community is also interested in the personal side of the scientists. This paper is devoted to a single statement made by Stephen Timoshenko in his autobiographical book. Specifically, it concerns Timoshenko's at least partial "explanation" of the Holocaust that took place during WWII. Whereas Timoshenko's statement constituted, to the present writer, open antisemitism, it does not seem to disturb many researchers who continue to honor him in various ways. "Nonsense is nonsense, but the history of nonsense is scholarship," according to Saul Lieberman. Hence the present article presents an investigation of Timoshenko's nonsensical and overly antisemitic statement. This author corresponded with a number of historians of science all repudiating Timoshenko's assertions. Most importantly, the correspondents shed additional vivid light on the Holocaust as experienced by Jewish scientists. [ABSTRACT FROM AUTHOR]

Physical systems are modeled by field equations; these are coupled, partial differential equations in space and time. Field equations are often given by balance equations and constitutive equations, where the former are axiomatically given and the latter are thermodynamically derived. This approach is useful in thermomechanics and electromagnetism, yet challenges arise once we apply it in damage mechanics for generalized continua. For deriving governing equations, an alternative method is based on a variational framework known as the extended Noether's formalism. Its formal introduction relies on mathematical concepts limiting its use in applied mechanics as a field theory. In this work, we demonstrate the power of extended Noether's formalism by using tensor algebra and usual continuum mechanics nomenclature. We demonstrate derivation of field equations in damage mechanics for generalized continua, specifically in the case of strain gradient elasticity. Physical systems are modeled by field equations; these are coupled, partial differential equations in space and time. Field equations are often given by balance equations and constitutive equations, where the former are axiomatically given and the latter are thermodynamically derived. This approach is useful in thermomechanics and electromagnetism, yet challenges arise once we apply it in damage mechanics for generalized continua. For deriving governing equations, an alternative method is based on a variational framework known as the extended Noether's formalism.... [ABSTRACT FROM AUTHOR]

Due to the fact that it serves as both a pump and a compressor, the helico-axial multiphase pump is better suited for mixed-transport oil-gas two-phase flow and is frequently used for deep-sea oil extraction. The gas–liquid separation caused by the asynchrony of the gas–liquid two-phase medium is the primary cause of the damage or failure of the helico-axial multiphase pump in the project, resulting in the pump's damage or inability to operate. To investigate the variation of phase separation in the helico-axial multiphase pump under diverse operating conditions, a test system was designed and the theory of fluid flow mechanics was applied. The effects of different flow fields on the energy conversion characteristics of the pump were investigated. The results indicate that the gas–liquid separation position in the impeller occurs near the 2/3 of the airfoil bone line. After the gas–liquid separation, gas mass will be formed, pocket flow will be readily induced, and the gas block-up phenomenon will result in energy loss in the compression unit. Simulations indicate that the static pressure recovery and total pressure loss in a diffuser fluctuate over time. The static pressure recovery efficacy of the diffuser is highest when the imported gas volume fraction is 10% and lowest when the imported gas volume fraction is 60%. On the surface of the impeller blade, perpendicular to the flow direction, the separation phenomenon near the hub side is more severe than that near the rim. Along the flow direction, the pattern of phase separation is comparable. [ABSTRACT FROM AUTHOR]

Three recent breakthroughs due to AI in arts and science serve as motivation: An award winning digital image, protein folding, fast matrix multiplication. Many recent developments in artificial neural networks, particularly deep learning (DL), applied and relevant to computational mechanics (solid, fluids, finite-element technology) are reviewed in detail. Both hybrid and pure machine learning (ML) methods are discussed. Hybrid methods combine traditional PDE discretizations with ML methods either (1) to help model complex nonlinear constitutive relations, (2) to nonlinearly reduce the model order for efficient simulation (turbulence), or (3) to accelerate the simulation by predicting certain components in the traditional integration methods. Here, methods (1) and (2) relied on Long-Short-Term Memory (LSTM) architecture, with method (3) relying on convolutional neural networks. Pure ML methods to solve (nonlinear) PDEs are represented by Physics-Informed Neural network (PINN) methods, which could be combined with attention mechanism to address discontinuous solutions. Both LSTM and attention architectures, together with modern and generalized classic optimizers to include stochasticity for DL networks, are extensively reviewed. Kernel machines, including Gaussian processes, are provided to sufficient depth for more advanced works such as shallow networks with infinite width. Not only addressing experts, readers are assumed familiar with computational mechanics, but not with DL, whose concepts and applications are built up from the basics, aiming at bringing first-time learners quickly to the forefront of research. History and limitations of AI are recounted and discussed, with particular attention at pointing out misstatements or misconceptions of the classics, even in well-known references. Positioning and pointing control of a large-deformable beam is given as an example. [ABSTRACT FROM AUTHOR]

Large language models (LLMs), such as ChatGPT and PaLM, are able to perform sophisticated text comprehension and generation tasks with little or no training. Alongside their broader societal impacts, these capabilities carry great promise for the physical sciences, including applied mechanics. We present a summary of recent developments in these models, their application to mechanics and adjacent fields, and a perspective on their future use in applied mechanics, taking into account their limitations and the unique challenges of the field. [ABSTRACT FROM AUTHOR]

The current Eurocode revision process is sought to improve Eurocode 7 for application to rock engineering, while including only techniques and procedures that are in widespread customary use. The revision process has exposed much about the application of the Eurocodes to rock engineering, thereby offering hints as to what material should be included in the next revision – tentatively suggested for publication in 2035. Crucially, ideas have developed about how rock engineering practice may need to develop to embrace the principles on which the Eurocodes are based. In particular, aspects of determining the properties of rock masses, and design verification by observational methods, partial factors, numerical modelling, and prescriptive rules are all thought to require significant improvement or dramatic modification. This paper highlights challenges identified regarding the application of the Eurocodes to rock engineering, and which will need to be addressed in the future. Ideas are presented about how these challenges may be overcome, but these are given in the spirit of stimulating ongoing conversation within the rock mechanics and rock engineering community rather than presenting definite proposals. [ABSTRACT FROM AUTHOR]

The lever law of Archimedes is widely known since classical antiquity. It is used in many practical applications. Ample experience confirms its validity. Therefore, the lever law sometimes appears obvious or trivial. Its manifestation in the literature of physics ranges from common ignorance through rare marked appreciation to erroneous application of its mathematical content. Since medieval times, the groundbreaking findings of Galilei and Newton concerning the motion of bodies have shaped mechanics as an important branch of physics. On the contrary, it appears that the statics of antiquity with its essential element, the lever law, has gained less popularity despite its importance. In the following, this is demonstrated in terms of citations. For engineering mechanics, this implies to base the fundamental assumptions on the ideas of Archimedes and Newton as consistently as possible. [ABSTRACT FROM AUTHOR]

The procedure of experimental determination of statistical characteristics of own electromagnetic radiation of a laboratory mock-up of an SPT-70 stationary plasma thruster developed by the Research Institute of Applied Mechanics and Electrodynamics of the Moscow Aviation Institute is described. The study investigated the temporal complex implementation of the processes of radiation of the SPT-70 with a sampling duration of 1 ms and an analysis band of 140 MHz for characteristic central frequencies of 0.9, 1.050, 1.200, and 1.350 GHz (discharge power of 600 W, horizontal polarization) when working on various working bodies. The conducted studies allowed to obtain estimates of the statistical characteristics of the SPT-70 radiation for prospective working bodies The new results should be attributed to the fact that the obtained distribution laws for the common-phase and quadrature components of the complex envelope process of radiation differ significantly from the Gaussian one. As for the distribution of the amplitude envelope process, in general, there is a difference from the Rayleigh distribution law. In the transition from xenon to krypton, the degree of negativity and the difference from Rayleigh's law increase. At the same time, the law of phase distribution of the complex envelope process is close to uniform and invariant to the type of working body. [ABSTRACT FROM AUTHOR]

Possible aspects of violation of the functional safety of spacecraft in terms of electromagnetic compatibility with electric rocket thrusters in their work on alternative working substances are considered. The procedure of experimental determination of spectral–time characteristics of own electromagnetic radiation of laboratory model of stationary plasma thruster SPT-70 developed by the Research Institute of Applied Mechanics and Electrodynamics of the Moscow Aviation Institute is described. Measurements of noise emissions were carried out on a vacuum installation with a "radiotransparent" compartment and a shielded echo-free camera in the frequency range of 1–12 GHz for typical discharge capacities (600, 800, and 1000 W), vertical and horizontal polarization, and various working substances used (krypton and xenon). The conducted studies have allowed obtaining new comparative results of the assessment of spectral characteristics of SPT-70 radiation for standard modes and prospective working bodies within the orthogonal polarization bases. The new results should include information about the radiation characteristics of SPT-70 in the time area. It is shown that the transition from xenon to krypton retains the pulsed nature of the radiation of a stationary plasma thruster, leading not only to an increase in the amplitude of pulses, but also to an increase in the frequency of repetition of "bursts" and an increase in their duration, which requires additional measures to ensure electromagnetic compatibility in order to preserve the functional safety of the spacecraft. [ABSTRACT FROM AUTHOR]

The article in the Journal of Physiology discusses the markers of cerebral autoregulation dynamics, focusing on critical closing pressure (CrCP) and resistance-area product (RAP). The study by Panerai et al. (2020) and Payne (2024) highlights the different time constants associated with dynamic cerebral autoregulation, with CrCP and RAP exhibiting distinct responses. The analysis suggests that CrCP tracks outlet pressure, potentially corresponding to venous pressure, while RAP is primarily governed by changes in radius. Further research is needed to explore the implications of these dynamics for clinical applications. [Extracted from the article]

Thermal transport through nanosystems is central to numerous processes in chemistry, material sciences, and electrical and mechanical engineering, with classical molecular dynamics as the key simulation tool. Here, we focus on thermal junctions with a molecule bridging two solids that are maintained at different temperatures. The classical steady state heat current in this system can be simulated in different ways, either at the interfaces with the solids, which are represented by thermostats, or between atoms within the conducting molecule. We show that while the latter, intramolecular definition feasibly converges to the correct limit, the molecule–thermostat interface definition is more challenging to converge to the correct result. The problem with the interface definition is demonstrated by simulating heat transport in harmonic and anharmonic one-dimensional chains illustrating unphysical effects such as thermal rectification in harmonic junctions. [ABSTRACT FROM AUTHOR]

Horizontal wood diaphragm systems, whether decked with conventional or mass timber panels, transfer wind and seismic loads to vertical elements of the lateral force-resisting system, in flexible, rigid, or semirigid ways. Characterizing and calculating the resulting diaphragm deflections will help determine the distribution of forces to critically loaded components and a significant portion of lateral building translations and rotations. Deflection equations for sheathed wood structural panel (WSP) diaphragms are well established in US design standards in a four-term expression that models flexural, shear, and fastener-slip deformations, but similar equations for cross-laminated timber (CLT) diaphragms have yet to unfold, despite growing industry consensus that CLT panels make efficient slabs and decks. Building code standards require CLT diaphragm deflections be computed using the principles of engineering mechanics. The current three-term and four-term deflection equations for WSP diaphragms are based on various assumptions that are often outpaced by current design practices. This is the second of two companion papers, in which the first paper provides the full generalized derivation of the current four-term WSP diaphragm deflection expression with a mechanics-based expansion to unify both potential WSP and CLT applications. This second paper builds on the first paper by expanding the generalized equation with implementation insights unique to WSP and CLT diaphragms. The various challenges of calculating diaphragm deflections associated with the current design practices are discussed with suggestions to assist in implementation. In general, the computation of diaphragm deflections has become increasingly important ever since equations were first developed for WSP systems around 70 years ago. Deflections are routinely computed to evaluate building separations, property line setbacks, P-delta instability, and evaluation of nonstructural damage from interstory drift. Additionally, appropriate engineering modeling requires accurate diaphragm stiffness values to characterize diaphragms as rigid, semirigid, or flexible. The mechanics-based equations in this paper are presented in a form that will be useful to today's practitioners to produce more rational building designs. [ABSTRACT FROM AUTHOR]

Since the Middle Ages, human-powered tools and machines have played an important role in societies. Prominent among these are pedal-powered machines, which harness the overall power from the strongest muscles in the human body. The article identifies a historical taxonomy of pedal-powered machines to provide designers with an orientation map for devising new solutions, suggesting some contexts in which today's pedal-powered machines can re-purpose ancient mechanisms to perform an innovative function. The reduction in energy consumption, the low environmental impact, and the autonomy of the process, in fact, can represent not only a technical rediscovery of engineering, but also a new way of supporting human subsistence. [ABSTRACT FROM AUTHOR]

The present work proposes an object‐oriented approach for the solution of problems in two‐dimensional engineering mechanics. New classes (in the terminology of object‐oriented programming) are proposed and implemented in the popular programming language 'Python.' These classes, along with the symbolic computation module of Python 'sympy,' enable one to reduce the solution of a large class of problems in undergraduate engineering mechanics to a set of Python statements. These statements are definitions of objects as instances of the proposed classes and calling of their relevant methods. If the thought process in the manual solution is represented by a flowchart, the present work can be viewed as a flowchart translator. As all the calculations are automatically performed, the present work relieves the student from the burden and fear of lengthy calculations. Different diagrammatic representations of velocity, acceleration, shear force, and bending moments are included for better physical understanding. It is believed that the proposed simple implementation would make problem‐solving and the learning process more enjoyable. Apart from a standard PC, the proposed work runs on a single‐board computer (tested in raspberry pi 4) and on an Android mobile device. A student feedback study ascertains the acceptability of the proposed method. [ABSTRACT FROM AUTHOR]

The text is a summary of a special issue of the Journal of Vibration Engineering & Technologies, which is based on contributions presented at the 10th International Conference on Wave Mechanics and Vibration (WMVC) held in Lisbon, Portugal in July 2022. The conference aimed to bring together researchers and professionals working on wave mechanics and vibration-related problems in various fields. The special issue includes articles covering topics such as nonlinear dynamics, wave propagation, railway mechanics, structural damage identification, impact mechanics, vibration transmission, aerospace structures, computational efficiency, musical instruments, and general topics. The articles present research findings and propose methods for optimizing vibration systems, analyzing the effects of various factors on performance, and improving the accuracy and reliability of damage detection methods, among other topics. The special issue provides a comprehensive overview of current problems in wave mechanics and vibration engineering and offers valuable insights for researchers and students in the field. [Extracted from the article]

In this work, we will try to find lump solutions, interaction between lump wave and solitary wave solutions, kink-solitary wave solutions and shock wave-type solutions to (3 + 1) -dimensional generalized nonlinear evolution equation arising in the shallow water waves. The lump solutions, the interaction between lump wave and solitary wave solutions and kink-solitary wave solutions are derived with symbolic computation based on a logarithmic derivative transform which is derived by the help of Hirota's simple method. The shallow water waves in this equation are associated with some natural problems such as tides, storms, atmospheric currents and tsunamis. For the physical presentation of the solutions, we draw 3D and counter graphics by giving the suitable values to include the free parameters. We believe that disciplines such as mathematical physics, nonlinear dynamics, fluid mechanics and engineering sciences can benefit from this study. [ABSTRACT FROM AUTHOR]

Quantum Mechanics (QM) stands alone as a (very) successful physical theory, but the meaning of its variables and the status of many quantities in the mathematical formalism is obscure. This unique situation prompted the need for attribution of a physical meaning to the latter, a procedure known as interpretation. On the other hand, the study of QM is usually presented, even to future scientists, within the only framework developed by Bohr and the Copenhagen researchers, known as the Copenhagen interpretation. As a contribution to the understanding and teaching of Quantum Mechanics, aimed to a broader and deeper appreciation of its fundamentals, including contemplating alternatives and updated interpretations for physicists and philosophers interested in the study of exact sciences (through Ontology, Epistemology, Logic or the Theory of Knowledge), we present a set of Conceptual Diagrams elaborated and designed to expose and facilitate the visualization of elements intervening in any interpretation of Quantum Mechanics and apply them to several well‐developed cases of the latter. [ABSTRACT FROM AUTHOR]

The paper presents a method for processing positional observations of near-Earth objects using a numerical model of satellite motion developed at the Research Institute of Applied Mathematics and Mechanics of Tomsk State University (NII PMM TSU). The root-mean-square error of orbit improvement without rejection of observations for such objects does not exceed 0.3″ over a seven-day time interval. The results of the presentation of observations for the next occurrence of the object are obtained, which makes it possible to find the object in a time interval of five months. The orbit has been refined in the joint processing of measurements on several occurrences of the object over a six-month time interval. All results were obtained from observations made on the equipment of the Terskol Observatory Shared Use Center. [ABSTRACT FROM AUTHOR]

Waves are an integral component of teaching in coastal engineering. Some aspects of wave theory are however complex and outside the scope of e.g. introductory courses, so that only the results of the theory are used. For other wave effects such as overtopping, no theory exists, and purely empirical formulas are employed. This limits the students' understanding of the problems. At Southampton University, we developed simple models for wave effects to improve the teaching. The models rely on basic hydraulic engineering principles such as continuity, conservation of energy and momentum, with the condition that the results are reasonably close to those from more complex theories or from experiments. In this article, two such models for the propagation speed of a solitary wave, and for the shallow water breaking criterion, will be presented. The results from both models are surprisingly close to the textbook formulas or values. [ABSTRACT FROM AUTHOR]

[Display omitted] Microrheology, the study of fluids on micron length-scales, promises to reveal insights into cellular biology, including mechanical biomarkers of disease and the interplay between biomechanics and cellular function. Here a minimally-invasive passive microrheology technique is applied to individual living cells by chemically binding a bead to the surface of a cell, and observing the mean squared displacement of the bead at timescales ranging from milliseconds to 100s of seconds. Measurements are repeated over the course of hours, and presented alongside analysis to quantify changes in the cells' low-frequency elastic modulus, G 0 ′ , and the cell's dynamics over the time window ∼ 10 − 2 s to 10 s. An analogy to optical trapping allows verification of the invariant viscosity of HeLa S3 cells under control conditions and after cytoskeletal disruption. Stiffening of the cell is observed during cytoskeletal rearrangement in the control case, and cell softening when the actin cytoskeleton is disrupted by Latrunculin B. These data correlate with conventional understanding that integrin binding and recruitment triggers cytoskeletal rearrangement. This is, to our knowledge, the first time that cell stiffening has been measured during focal adhesion maturation, and the longest time over which such stiffening has been quantified by any means. Here, we present an approach for studying mechanical properties of live cells without applying external forces or inserting tracers. Regulation of cellular biomechanics is crucial to healthy cell function. For the first time in literature, we can non-invasively and passively quantify cell mechanics during interactions with functionalised surface. Our method can monitor the maturation of adhesion sites on the surface of individual live cells without disrupting the cell mechanics by applying forces to the cell. We observe a stiffening response in cells over tens of minutes after a bead chemically binds. This stiffening reduces the deformation rate of the cytoskeleton, although the internal force generation increases. Our method has potential for applications to study mechanics during cell-surface and cell-vesicle interactions. [ABSTRACT FROM AUTHOR]

The paper proves the minimax theorem for a specific class of functions that are defined on branching polylines in a linear space, not on convex subsets of a linear space. The existence of a saddle point for such functions does not follow directly from the classical minimax theorem and needs individual consideration based both on convex analysis and graph theory. The paper presents a self-sufficient analysis of the problem. It contains everything that enables a plain understanding of the main result and its proof and avoids using concepts outside the scope of obligatory mathematical education of engineers. The paper is addressed to researchers in applied mechanics, engineering, and other applied sciences as well as to mathematicians who lecture convex analysis and optimization methods to non-mathematicians. [ABSTRACT FROM AUTHOR]

The present research article deals with the study of a boundary value problem of a one-dimensional semi-infinite hygro-thermoelastic rod of length l. The deformation of the rod is under consideration when the left boundary of the hygro-thermoelastic rod is subjected to a sudden heat source. The solutions of the considered variables are decomposed in terms of normal modes. Analytical expressions of displacement, moisture concentration, temperature field, and stresses are obtained and presented graphically for different periods. By studying the one-dimensional thermal shock problem for a semi-infinite hygrothermoelastic rod, the authors aim to gain insights into the fundamental behavior of materials subjected to rapid temperature changes and moisture effects. [ABSTRACT FROM AUTHOR]

The use of the coordinated silver (I) complex based on solvate ionic liquid in epoxy resins is reported to enable unprecedented electrical and thermomechanical properties. The novel hybrid material is aligned at the molecular level using an electric field, demonstrating high electrical conductivity, excellent energy storage properties, and rapid curing behavior. The electric‐field treated epoxy resin system shows a maximum electric conductivity of 2.05 × 105 S m−1, 20 folds of the same untreated system, and 3 folds of the same treated system but with 5.0% silver nanoparticles. Furthermore, this system shows an ultrafast curing rate of around 500 s at a temperature of 42.0 °C and reveals excellent energy storage achieving an average capacitance of 27.5 F g−1 at a scan rate of 1.0 mV s−1. Quantum mechanics is applied and the synchrotron beamline is utilized to optimize and investigate the properties of the system, opening the door to the next generation of thermoset polymers with multifunctional properties. [ABSTRACT FROM AUTHOR]

The finite fault stochastic method is one of the most effective approaches widely used in seismic engineering to simulate near-field high-frequency ground motion (Motazedian and Atkinson in Bull Seismol Soc Am 95(3):995–1010, 2005; Boore in Bull Seismol Soc Am 99(6):3202–3216, 2009). However, the widely used static and dynamic corner frequencies are derived based on the ratio of rupture velocity to shear-wave velocity of 0.69 (Brune in J Geophys Res 75(26):4997–5009, 1970, J Geophys Res 76(20):5002–5002, 1971; Wang in Research on stochastic simulation method for high frequency of ground motions, Institute of Engineering Mechanics, China Earthquake Administration, Harbin, 2017), which obviously eliminates the influence of rupture velocity on corner frequency. In the currently distributed stochastic simulation program, the ratio of rupture velocity to shear-wave velocity is often set to 0.8 and is adopted as one of the important input parameters, which is obviously inconsistent with the assumption when deriving the corner frequency. In order to ensure that the input parameter values are consistent with the basic assumptions used in deriving the parameters, this study redefines the corner frequency associated with the rupture velocity, based on the displacement representation theory providing additional theoretical significance to the corner frequency. Also, the influence of rupture velocity on source rise time is investigated, and the improved corner frequency is verified by the Mw 6.6 Lushan earthquake occurred on April 20, 2013 (local time) in China. The comparison of the static and dynamic corner frequencies indicates that the simulated PGA and PSA obtained by the improved corner frequency are consistent with the observed values. Moreover, the corner frequency proposed in this study can further study the influence of nonuniform rupture velocity on the synthetic results. [ABSTRACT FROM AUTHOR]

As a kind of dynamical system with a particular nonlinear structure, a multi-time scale nonlinear system is one of the essential directions of the current development of nonlinear dynamics theory. Multi-time scale nonlinear systems in practical applications are often complex forms of coupling of high-dimensional and high codimension characteristics, leading to various complex bursting oscillation behaviors and bifurcation characteristics in the system. For exploring the complex bursting dynamics caused by high codimension bifurcation, this paper considers the normal form of the vector field with triple zero bifurcation. Two kinds of codimension-2 bifurcation that may lead to complex bursting oscillations are discussed in the two-parameter plane. Based on the fast–slow analysis method, by introducing the slow variable W = A sin (ω t) , the evolution process of the motion trajectory of the system changing with W was investigated, and the dynamical mechanism of several types of bursting oscillations was revealed. Finally, by varying the frequency of the slow variable, a class of chaotic bursting phenomena caused by the period-doubling cascade is deduced. Developing related work has played a positive role in deeply understanding the nature of various complex bursting phenomena and strengthening the application of basic disciplines such as mechanics and mathematics in engineering practice. [ABSTRACT FROM AUTHOR]

A solid conceptual understanding is essential for students to succeed in all academic disciplines. Student misconceptions are correlated with their poor academic performance and high attrition rates. It is especially important to correct student misconceptions in science-based undergraduate engineering mechanics courses that cover numerous fundamental concepts. This paper aims to conduct a research study on the effects of an instructional intervention called enhanced hands-on experimentation on identifying and correcting student misconceptions about work and energy in a second-year undergraduate engineering mechanics course. As a comparison, the effects of traditional textbook instruction were also investigated. The present study is qualitative research involving the transcriptions and coding of qualitative verbal data collected through a think-aloud approach. To offer deep insights into the effects of enhanced hands-on experimentation and traditional textbook instruction on each individual student participant, 12 undergraduate students were recruited to participate in the present study. This sample size is typical in qualitative research. The student participants were assigned into an enhanced hands-on experimentation group and a traditional textbook instruction group. Data was collected using a think-aloud approach while student participants took a pre-test and a post-test before and after the enhanced hands-on experimentation or traditional textbook instruction intervention. Qualitative verbal data collected through think-aloud were quantitatively analyzed to compare the effectiveness of the two types of interventions on correcting student misconceptions about work and energy in engineering mechanics. Compared to traditional textbook instruction, enhanced hands-on experimentation is significantly more effective in correcting student misconceptions about work and energy. As the consequence of enhanced hands-on experimentation, student participants achieved a group-average normalized learning gain of 55.8%, and the overall reduction rate of students' misconception instances was 47.9%. The enhanced hands-on experimentation can be employed as an effective supplemental tool to help correct student misconceptions about work and energy in engineering mechanics. [ABSTRACT FROM AUTHOR]

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