The concept of life skills is related to the way of life that emphasises the mutual exchange of knowledge, attitudes, and interpersonal skills in education. Its objective is to develop diverse skills among students and prepare them to face life’s challenges with determination. The World Health Organization has defined life skills as “the positive behaviours and tendencies that enable a person to adapt in day-to-day life.” Life skills are the abilities that enable a person to adapt and exhibit positive behaviour, allowing them to deal effectively with the problems and challenges of daily life. Life is a unique gift. Therefore, by equipping life with various skills, happiness, peace, and prosperity are created. In this research, with the objectives of the study in mind, an analytical examination of life skills among secondary-level students has been conducted. This research study examines the effects of living conditions, gender, and social class on students’ life skills and presents the findings. Future researchers can build upon this, and other factors affecting the research can also be explored.
Ahmed Abdulsahib, Dhirgham Alkhafaji, Ibrahim Albayati
Natural heat transfer is studied in a square enclosure containing a heat sink in the presence of a hybrid nanofluid (MWCNT and Fe3O4). The right wall is kept cool (Tc), while the left wall is hot (Th), and the upper wall and lower wall are thermally insulated. The study is carried out by making slots with different thicknesses (st = 0.01 and 0.02) and lengths (sh = 0.1 to 0.4) for each fin of the heat sink to increase heat transfer in the heat sink by using a Rayleigh number of 103 to 106 and a solid volume fraction (ϕ = 0.02). Also, internal circular cold bodies are added in the tip and between the fins with a diameter of 0.05 and different numbers (No = 2, 4, 6, 8, and 12). According to numerical results, the average Nusselt number increases with the Rayleigh number, slot thickness, and length. The optimal condition was slot thickness (st = 0.02) and length (sh = 0.4), which increased the average Nusselt number by 37.7% over solid fins. When cold circular internal bodies are present, an increase in the stream function and a better distribution of isotherm lines are generally observed. Nu increases by 62% when there are internal bodies at the tip of the fins (No = 6), 71.5% when there are internal bodies between the fins (No = 6), and 78% when there are internal bodies at the tip and between the fins (No = 12).
We investigate the adiabatic elimination of fast variables in relativistic stochastic mechanics, which is analyzed by using the equation of motion and the distribution function, with relativistic corrections explicitly derived. A new dimensionless parameter is introduced to characterize the timescale. The adiabatic elimination is compared with the path integral coarse graining, which is more general yet computationally demanding.
Physicist and Nobel Laureate Richard P. Feynman once remarked ``We choose to examine a phenomenon which is impossible, absolutely impossible, to explain in any classical way, and which has in it the heart of quantum mechanics. In reality, it contains the only mystery. We cannot make the mystery go away by ``explaining'' how it works. We will just tell you how it works. In telling you how it works, we will have told you about the basic peculiarities of all quantum mechanics'' [Feynman RP, Leighton RB, Sands M (1963 and 1965)]. The phenomenon of interference is ubiquitous in the quantum world and indeed holds within itself the explanation for many counterintuitive quantum phenomena. In this review, we choose to focus on a few ramifications and manifestations of quantum interference that have deep implications for the foundations of quantum mechanics. These include single-photon or second-order interference, two-photon or fourth-order interference and higher-order interference.
Vladyslav PROTSENKO, Volodymyr MALASHCHENKO, Valentyn NASTASENKO
et al.
The article deals with mechanical engineering, and transport machines, namely the elevator brake mechanism structure. The article aims to study the number and location of redundant constraints in elevator brake mechanisms and to depict their impact on brake reliability and transportation safety. To study the structure of the mentioned mechanisms, we used classical methods of applied mechanics plus the circuit method of L. Reshetov. The structure of crane disc brakes with short-stroke DC electromagnet and long-stroke AC electromagnet mechanisms was analyzed and redundant constraints were identified. It was shown that the presence of redundant constraints causes friction torque oscillation and lead to load distribution unevenness between brake elements. Based on the provided analysis, construction improvement events should be implemented to remove the most dangerous redundant constraints.
Magdalena Schreter-Fleischhacker, Peter Munch, Nils Much
et al.
Abstract We present accurate and mathematically consistent formulations of a diffuse-interface model for two-phase flow problems involving rapid evaporation. The model addresses challenges including discontinuities in the density field by several orders of magnitude, leading to high velocity and pressure jumps across the liquid–vapor interface, along with dynamically changing interface topologies. To this end, we integrate an incompressible Navier–Stokes solver combined with a conservative level-set formulation and a regularized, i.e., diffuse, representation of discontinuities into a matrix-free adaptive finite element framework. The achievements are three-fold: First, we propose mathematically consistent definitions for the level-set transport velocity in the diffuse interface region by extrapolating the velocity from the liquid or gas phase. They exhibit superior prediction accuracy for the evaporated mass and the resulting interface dynamics compared to a local velocity evaluation, especially for strongly curved interfaces.Second, we show that accurate prediction of the evaporation-induced pressure jump requires a consistent, namely a reciprocal, density interpolation across the interface, which satisfies local mass conservation. Third, the combination of diffuse interface models for evaporation with standard Stokes-type constitutive relations for viscous flows leads to significant pressure artifacts in the diffuse interface region. To mitigate these, we propose to introduce a correction term for such constitutive model types. Through selected analytical and numerical examples, the aforementioned properties are validated. The presented model promises new insights in simulation-based prediction of melt–vapor interactions in thermal multiphase flows such as in laser-based powder bed fusion of metals.
Mechanics of engineering. Applied mechanics, Systems engineering
Tomas Vaitkunas, Paulius Griskevicius, Gintautas Dundulis
et al.
Abstract Numerical fatigue process modelling is complex and still an open task. Discontinuity caused by fatigue cracks requires special finite element techniques based on additional parameters, the selection of which has a strong effect on the simulation results. Moreover, the calculation of fatigue life according to empirical material coefficients (e.g., Paris law) does not explain the process, and coefficients should be set from experimental testing, which is not always possible. A new nonlocal continuum mechanics formulation without spatial derivative of coordinates, namely, peridynamics (PD), which was created 20 y ago, provides new opportunities for modelling discontinuities, such as fatigue cracks. The fatigue process can be better described by using the atomistic approach-based kinetic theory of fracture (KTF), which includes the process temperature, maximum and minimum stresses, and loading frequency in its differential fatigue damage equation. Standard 316L stainless steel specimens are tested, and then the KTF-PD fatigue simulation is run in this study. In-house MATLAB code, calibrated from the material S‒N curve, is used for the KTF-PD simulation. A novel KTF equation based on the cycle stress‒strain hysteresis loop is proposed and applied to predict fatigue life. The simulation results are compared with the experimental results, and good agreement is observed for both symmetric and asymmetric cyclic loading.
Mechanics of engineering. Applied mechanics, Systems engineering
Roberto Casadei, Gianluca Aguzzi, Giorgio Audrito
et al.
Today's distributed and pervasive computing addresses large-scale cyber-physical ecosystems, characterised by dense and large networks of devices capable of computation, communication and interaction with the environment and people. While most research focusses on treating these systems as "composites" (i.e., heterogeneous functional complexes), recent developments in fields such as self-organising systems and swarm robotics have opened up a complementary perspective: treating systems as "collectives" (i.e., uniform, collaborative, and self-organising groups of entities). This article explores the motivations, state of the art, and implications of this "collective computing paradigm" in software engineering, discusses its peculiar challenges, and outlines a path for future research, touching on aspects such as macroprogramming, collective intelligence, self-adaptive middleware, learning, synthesis, and experimentation of collective behaviour.
The circular ring is linearly elastic and its cross-section is rectangular. Two deformation dependent distributed loads, that is follower loads, are applied simultaneously on the outer surface of the ring. The first load is a uniform pressure on the whole outer surface. The second load is uniform normal traction exerted on two surface parts situated in axially symmetric positions. Both loads are selfequilibrated independently from each other. A nonlinear FE program with 3D elements is used for the numerical analysis of a geometrically perfect and two imperfect rings. Displacement control is used in the equilibrium iterations. Equilibrium surfaces are determined in the space of three parameters such as one characteristic displacement coordinate, and two load factors. The stability analysis is performed in the knowledge of the equilibrium surfaces.
Computer engineering. Computer hardware, Mechanics of engineering. Applied mechanics
In modern global supply chains, intermodal and multimodal distribution has become essential means of transportation. The combination of different modes of transport is the most commonly used method for distributing shipments between continents. This paper examines and measures physical events, such as shock and impact, that occur while transporting 40ft long ISO containers using multiple modes of transport. These events can directly affect the integrity of packaged products and cause damage. The study focuses on events such as transshipments and handling of containers in hubs and terminals. The impact shock levels were separately analyzed in all three-dimensional directions, namely vertical, longitudinal, and lateral. The results indicate the percentage of occurrence below a given impact level using statistical characteristics of the events that occurred. The magnitude and mean of acceleration levels, pulse duration, and velocity change are also reported.
Engineering (General). Civil engineering (General), Mechanics of engineering. Applied mechanics
Based on the background and expertise gained during almost two decades of development and implementation of virtual laboratory applications for teaching mechanics in engineering faculties, the authors propose a novel approach for this field, in which students themselves become developers of educational computer simulations. The method, called DYOVL (“Do Your Own Virtual Laboratory”), was applied, first experimentally and then on a regular basis, with gradual optimization during consecutive years, within the practical sessions of the mechanics course taught to students in automatic control and computers. An educational website, containing application examples and several downloadable resources, was recently developed, to assist teaching by the new method. The co‐creative character of this process is manifold, as students work together with the teaching staff and with their team colleagues to program virtual laboratory applications or to suggest improvements for the existing ones. The method demonstrated favorable outcomes in terms of engagement, motivation, and inclusiveness, as well as a positive attitude of the students, shown both by pre‐ and during‐COVID satisfaction surveys. To assist potentially interested academic staff in implementing this approach in their universities, detailed methodological guidance is provided.
The paper deals with a body having a random 3D-distribution of two-phase inclusions: spheroidal mutually parallel voids as well as differently oriented reinforcing parallel stiff spheroidal short fibers. By the effective field approach the effective stiffness fourth-order tensor is formulated and found numerically. Simultaneous and sequential embeddings of inclusions are compared. Damage evolution is described by modified Vakulenko’s approach to endochronic thermodynamics. A brief account of the problem of effective elastic symmetry is given. The results of the theory are applied to the damageelasto- viscoplastic strain of reactor stainless steel AISI 316H.
Laser peening (LP) is a well-established technique for introducing compressive residual stress (RS) near the surface of metal components, to improve their high-cycle fatigue properties. The authors have developed a compact LP device with a thumb-sized Nd:YAG microchip laser mounted on a collaborative robot arm. The device was applied to 9-mm-thick HT780 high-strength steel plate samples with irradiated pulse energies of 7.5−8.0 mJ, spot sizes of 0.42−0.58 mm and pulse densities of 100−1,600 pulses/mm2. X-ray diffraction showed that the maximum compressive RS was over 500 MPa near the surface, and the LP effect reached a depth of approximately 0.1 mm from the surface. Butt-welded HT780 samples were laser-peened with a pulse energy of 7.7 mJ, spot size of 0.49 mm and pulse density of 800 pulses/mm2. Then, the samples were subjected to a uniaxial fatigue test with a stress ratio of 0.1. The results showed that the fatigue strength at 107 cycles was improved by at least 50 MPa, comparable to the improvement attained by LP in a previous study with a pulse energy of 200 mJ from a conventional Nd:YAG laser.
Mechanics of engineering. Applied mechanics, Technology
The loads in the deep beams are transmitted diagonally from the load area to the support area by means of the strut and the tie. It is characterized by having a small span to depth ratio. which causes the distribution of stresses to be non-linear within the beam, which motivates researchers to study the effect of the placing of longitudinal hollows and the extent to which these holes affect the behavior and distribution of stresses for these types of beams. In addition to the advantages added by longitudinal hollow to the beam such as reducing weight and passing various electrical and mechanical services...etc. This study investigated the effect of making longitudinal circular holes (with a diameter of 50mm) with a slope on the structural behavior of three deep beams with a solid sample as a reference where the slope used was 0%, 4.3%, and 7.8%. The results showed that making holes reduces the load capacity of the deep beam, a decrease in the failure load was observed by 7.56%, 8.96%, and 11.2% for hollow beams with a slope of 0%, 4.3%, and 7.8%, respectively. Also, the appearance of flexural cracking increased by 2.66%, 2.66%, and 6.66%.and 2.14%, 3.52%, and 7.14%, respectively, for shear cracks. While the effect was small for the neutral axis location as well as for the vertical deflection.
Engineering machinery, tools, and implements, Mechanics of engineering. Applied mechanics
The paper presents a new efficient and robust method for rare event probability estimation for computational models of an engineering product or a process returning categorical information only, for example, either success or failure. For such models, most of the methods designed for the estimation of failure probability, which use the numerical value of the outcome to compute gradients or to estimate the proximity to the failure surface, cannot be applied. Even if the performance function provides more than just binary output, the state of the system may be a non-smooth or even a discontinuous function defined in the domain of continuous input variables. In these cases, the classical gradient-based methods usually fail. We propose a simple yet efficient algorithm, which performs a sequential adaptive selection of points from the input domain of random variables to extend and refine a simple distance-based surrogate model. Two different tasks can be accomplished at any stage of sequential sampling: (i) estimation of the failure probability, and (ii) selection of the best possible candidate for the subsequent model evaluation if further improvement is necessary. The proposed criterion for selecting the next point for model evaluation maximizes the expected probability classified by using the candidate. Therefore, the perfect balance between global exploration and local exploitation is maintained automatically. The method can estimate the probabilities of multiple failure types. Moreover, when the numerical value of model evaluation can be used to build a smooth surrogate, the algorithm can accommodate this information to increase the accuracy of the estimated probabilities. Lastly, we define a new simple yet general geometrical measure of the global sensitivity of the rare-event probability to individual variables, which is obtained as a by-product of the proposed algorithm.
Tijmen Vermeij, Jorn Verstijnen, Tim Ramirez y Cantador
et al.
The continuous development of new multiphase alloys with improved mechanical properties requires quantitative microstructure-resolved observation of the nanoscale deformation mechanisms at, e.g., multiphase interfaces. This calls for a combinatory approach beyond advanced testing methods such as microscale strain mapping on bulk material and micrometer sized deformation tests of single grains. We propose a nanomechanical testing framework that has been carefully designed to integrate several state-of-the-art testing and characterization methods: (i) well-defined nano-tensile testing of carefully selected and isolated multiphase specimens, (ii) front&rear-sided SEM-EBSD microstructural characterization combined with front&rear-sided in-situ SEM-DIC testing at very high resolution enabled by a recently developed InSn nano-DIC speckle pattern, (iii) optimized DIC strain mapping aided by application of SEM scanning artefact correction and DIC deconvolution for improved spatial resolution, (iv) a novel microstructure-to-strain alignment framework to deliver front&rear-sided, nanoscale, microstructure-resolved strain fields, and (v) direct comparison of microstructure, strain and SEM-BSE damage maps in the deformed configuration. Demonstration on a micrometer-sized dual-phase steel specimen, containing an incompatible ferrite-martensite interface, shows how the nanoscale deformation mechanisms can be unraveled. Discrete lath-boundary-aligned martensite strain localizations transit over the interface into diffuse ferrite plasticity, revealed by the nanoscale front&rear-sided microstructure-to-strain alignment and optimization of DIC correlations. The proposed framework yields front&rear-sided aligned microstructure and strain fields providing 3D interpretation of the deformation and opening new opportunities for unprecedented validation of advanced multiphase simulations.
Matthew Grasinger,1, 2, ∗ Kaushik Dayal,3, 4, 5 Gal deBotton,6, 7 and Prashant K. Purohit8, † 1Materials and Manufacturing Directorate, Air Force Research Laboratory 2UES, Inc. 3Department of Civil and Environmental Engineering, Carnegie Mellon University 4Department of Materials Science and Engineering, Carnegie Mellon University 5Center for Nonlinear Analysis, Department of Mathematical Sciences, Carnegie Mellon University 6Department of Mechanical Engineering, Ben-Gurion University 7Department of Biomedical Engineering, Ben-Gurion University 8Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania (Dated: October 19, 2021)