Hasil untuk "Mechanics of engineering. Applied mechanics"

Mark Looi

The rapid advance of Generative AI into software development prompts this empirical investigation of perceptual effects on practice. We study the usage patterns of 147 professional developers, examining perceived correlates of AI tools use, the resulting productivity and quality outcomes, and developer readiness for emerging AI-enhanced development. We describe a virtuous adoption cycle where frequent and broad AI tools use are the strongest correlates of both Perceived Productivity (PP) and quality, with frequency strongest. The study finds no perceptual support for the Quality Paradox and shows that PP is positively correlated with Perceived Code Quality (PQ) improvement. Developers thus report both productivity and quality gains. High current usage, breadth of application, frequent use of AI tools for testing, and ease of use correlate strongly with future intended adoption, though security concerns remain a moderate and statistically significant barrier to adoption. Moreover, AI testing tools' adoption lags that of coding tools, opening a Testing Gap. We identify three developer archetypes (Enthusiasts, Pragmatists, Cautious) that align with an innovation diffusion process wherein the virtuous adoption cycle serves as the individual engine of progression. Our findings reveal that organizational adoption of AI tools follows such a process: Enthusiasts push ahead with tools, creating organizational success that converts Pragmatists. The Cautious are held in organizational stasis: without early adopter examples, they don't enter the virtuous adoption cycle, never accumulate the usage frequency that drives intent, and never attain high efficacy. Policy itself does not predict individuals' intent to increase usage but functions as a marker of maturity, formalizing the successful diffusion of adoption by Enthusiasts while acting as a gateway that the Cautious group has yet to reach.

Yuri Chirkunov, Yuri Skolubovich, Mihail Chirkunov et al.

The generalized axisymmetric model of fluid motion in a porous medium in the presence of a non-stationary external source or absorption is studied by methods of group (symmetry) analysis of differential equations. All its invariant submodels of rank 1 are studied. They are specified by invariant solutions of rank 1 of the equation of the original model. These solutions are obtained either explicitly, or their search is reduced to solving systems of ordinary differential equations of the first order. For explicit solutions at specific values of the parameters included in their expressions, graphs of the pressure distribution in the porous medium are constructed. The remaining solutions are used to study physically meaningful boundary value problems for which, at the initial moment of time, the pressure and either the rate of its change along the axis of symmetry or the radial rate of its change are specified at a fixed point of the medium. These boundary value problems are solved numerically for some specific values of the parameters included in them. Graphs of the functions determining these solutions are obtained. The conducted research is relevant in many areas of applied science and technology: filtration, soil mechanics, rock mechanics, oil field engineering, construction engineering, petroleum geology, biology and biophysics, materials science.

Akshay Balsubramani

Artificial intelligence models trained through loss minimization have demonstrated significant success, grounded in principles from fields like information theory and statistical physics. This work explores these established connections through the lens of statistical mechanics, starting from first-principles sample concentration behaviors that underpin AI and machine learning. Our development of statistical mechanics for modeling highlights the key role of exponential families, and quantities of statistics, physics, and information theory.

VS Morales-Salgado

Social physics is the application of ideas, concepts and tools from physics to study social phenomena. In this article, we present a mechanical theory underlying a mathematical treatment of social physics. We explore the possibility of using fundamental concepts like position, motion, inertia, and interaction, to effectively regard social phenomena analogously to particles interacting with each other in physics. From these concepts, along with heuristics of social change, we investigate the notions of free motion, motion under the influence of a net deterministic, as well as stochastic force. To test these ideas we model partisan preferences in the United States according to the outcomes of presidential elections.

Shang Wang, Xuelei Wang, Fei Peng

The students in vocational colleges are weak in mathematical calculation, which affects the teaching quality of Engineering Mechanics. In order to improve teaching quality, the research team propose a solution strategy combining simulation calculation and mathematical integral calculation. This article carried on the teaching practice starting from a typical problem raised by the students. The finite element model was established and simulated on a computer. The Mises stress nephogram and date were obtained by the simulation calculation, which solved the students’ doubts. These visual materials provide support for the students to understand the abstract concepts of Engineering Mechanics. However, the simulation only described the final results and the students could not get the specific calculation process from the finite element model. Subsequently, the detailed integral calculation process was sorted out by the teachers, which helped the students understand the strain accumulation of the prism. The result of integral calculation is 0.1143 mm, which is very close to the result of the simulation (0.1123 mm). The finite element analysis and calculus calculation process were sorted into the teaching materials of Engineering Mechanics. Subsequently, a teaching practice was applied to a class of 35 students. Teaching evaluation shows that teaching quality has been significantly improved. On the one hand, digital materials such as stress nephogram have the characteristics of visualization, which provides convenience for students to understand complex mechanics concepts. On the other hand, students’ interest in learning has been enhanced, and classroom interaction has increased significantly. This study provides a new way to answer complex questions in Engineering Mechanics teaching, which should be paid more attention and explored by more scholars.

Sorin Mihăilescu

Level crossing accidents are one of the largest groups of fatal accidents and it is often useful to investigate them from a safety point of view in order to avoid their recurrence. Level crossings are a serious hazard for rail safety killing more than 200 people/year in the EU. Material damages are also substantial in terms of loss of assets and disruptions to traffic. Crossing a level crossing without following signs is a widespread problem. Even in the case of an obvious violation of safety rules, the causative factor may come from the railway system. Accidents at level crossings have an obvious impact on railway safety regulation or safety management, if the accident was a result of deficiencies in the railway system (e.g. technical failures of infrastructure devices or rolling stock, staff not following procedures, deficiencies in the safety management system, etc.). In this context, the analysis of road accidents at railway level crossings in Romania helps to understand the current situation and the measures needed to modernize them to increase road safety.

Lenka Jakubovičová, Milan Vaško, Vladimir Kompis

Two types of Trefftz (T -) functions are often used - fundamental solutions with their singularities outside the given region and general solutions of homogenous differential equations. For elasticity problems the general solution of the homogeneous differential equation (equilibrium equation in displacements known as Lame- Navier equations) can be found in the polynomial form. In this paper we present the first type of T-functions. The paper deals with the investigation of accuracy and stability of the resulting system of discretized equations in relation to the position of the source (singularity) point. In this way non-singular reciprocity based boundary integral equations relate the boundary tractions and the boundary displacements of the searched solution to corresponding quantities of the known solutions. It was found that there exist an optimal relation of the distance of the singularity to the distance of the collocation points where both the integration accuracy and numerical stability are good.

Victor Maiboroda, Dmytro Dzhulii, Kostiantyn Zastavskyi

Background. For effective magneto-abrasive machining (MAM) of complex-shaped parts, comprehensive information is needed on the processes that occur when the magneto-abrasive tool (MAT) contacts with the surfaces being machined. Effective magneto-abrasive machining occurs in the presence of sufficient values of the normal and tangential components of the interaction forces between the MAT and the machined surfaces and the powder mixing during machining. Previously carried out analytical studies of dynamic parameters did not take into account the real conditions of the interaction of grains and their groups with machined surfaces. Objective. Complex analysis of the processes that occur during magneto-abrasive machining of parts made from different types of materials, based on the results of the study of the friction forces between the magneto-abrasive tool and the surface being machined and the drag forces during the movement of parts in the working zone of the machine. Methods. To achieve the set goal, the forces acting on the samples during their magneto-abrasive machining were measured with subsequent analytical analysis. Results. The complex analysis of the processes occurring during MAM in conditions of the annular working zone with large working gaps of parts made of various materials was carried out based on the results of the study of the friction and drag forces that occur when the part moves relative to the magneto-abrasive tool. Conclusions. It has been determined that when machining non-magnetic samples at the constant value of the magnetic field in the working zone, the specific drag forces are practically independent of the shape of the used powder. According to the analytical representation of the friction and drag forces, their ratio between their specific values was calculated. By the nature of the change in this ratio, it was found that it decreases with an increase in the velocity of samples movement along the working zone, and with an increase in the angular velocity of rotation of the samples around its axis, this value increases in the studied velocity range. It has been determined that at the velocity of movement along the working zone of 2.2 m/s, there is a slight increase in the ratio between the specific forces of friction and drag, which is associated with the action of ponderomotive forces that appear near the surface of the machined parts and lead to an increase in local magnetic forces in these zones.

Vahid Gholami Motlagh, Mohammd Ahmadzadehtalatapeh

In this research, possible methods to improve the air distribution patterns of an operating room (OR) employing CFD method are investigated. Laminar airflow (LAF), turbulent airflow (TAF), and LAF with the air curtain are examined. It is found that LAF and LAF with the air curtain cases are superior to TAF-based cases. The study shows that the LAF and LAF with the air curtain cases as the proposed configurations have an acceptable capability to maintain the indoor air conditions within the range recommended by the standards. According to the simulations, the LAF with the air curtain case is the most suitable case in terms of the contamination risk, and it is recommended to be implemented in the existing OR.

Sri Nugroho, Deni Fajar Fitriyana, Rifky Ismail et al.

Induction hardening (IH) is a popular choice for automotive components such as camshafts for its ability to harden portions of a component selectively. The camshaft will contact the tappet, connected to the rocker arm, to open and close the valve whenever the engine is running. This contact between the camshaft and the tappet causes wear on the camshaft surface. IH of the camshaft is required to improve wear resistance and service life, as well as core elasticity to absorb high torsional stresses. It is known that studies about IH on camshafts are still very limited. This study aims to determine the effect of the induction hardening and tempering treatment on the mechanical properties of the camshaft made of HQ 705 steel. The induction hardening carried out in this study uses different parameter settings such as heating time and output current. The camshaft specimen is hardened by static induction and then quenched in oil. The specimens are tempered after induction hardening with different temperatures and holding times to adjust the hardness level and reduce brittleness. Hardness, macro photographs, micrograph, and wear tests were conducted to determine the mechanical properties of the camshaft specimen after the induction hardening and tempering process. This study indicates that induction hardening with an output current of 747 A for 15 seconds followed by tempering at 150 °C for 15 seconds on specimen 1 produced the best mechanical properties. On the surface of these specimens found more martensite content while there was no microstructural change on the inside. The surface hardness of these specimens is 44 HRC (Rockwell C Hardness), while the inside is 26 HRC. Meanwhile, specific wear decreased by 45.45%.

M. Atar, K. Davey, R. Darvizeh

An important experimental approach for the testing of earthquake‐resistant structures is scaled experimentation with experimental designs impacted upon by the similitude theory of dimensional analysis. Unfortunately, the type of similitude provided by dimensional analysis seldom applies to complex structures, which is particularly problematic when scaling ratios are large. The issue is one of scale effects where the behaviour of the scaled version of any full‐size structure can be markedly different. Recently however a new theory of scaling called finite similitude has emerged in the open literature that confirms that the similitude offered by dimensional analysis is just one of a countable infinite number of alternative possibilities. The new theory of scaling raises the possibility that buildings and structures can be designed and tested in new ways and this aspect is the focus of this paper. Similitude rules for single and two scaled experiments are examined to illustrate the benefits provided by alternative forms of similitude. The two types of similitude examined are termed zeroth order and first order finite similitude, which are shown to be two forms in an infinite number of alternative possibilities efficiently defined using a recursive relationship. The theory of scaling is founded on the metaphysical concept of space scaling yet provides the means to establish all scale dependencies for structural components and high‐rise steel buildings along with buildings equipped with nonlinear‐fluid viscous dampers for resisting earthquake loading conditions. It is shown through case‐studies of increasing complexity how the new theory can be applied to reconstruct full‐scale behaviours but also revealed are some of the limitations of the new approach.

Izabela Rojek, Marek Macko, Dariusz Mikołajewski et al.

Artificial intelligence (AI) is changing many areas of technology in the public and private spheres, including the economy. This report reviews issues related to machine modelling and simulations concerning further development of mechanical devices and their control systems as part of novel projects under the Industry 4.0 paradigm. The challenges faced by the industry have generated novel technologies used in the construction of dynamic, intelligent, flexible and open applications, capable of working in real time environments. Thus, in an Industry 4.0 environment, the data generated by sensor networks requires AI/CI to apply close-to-real-time data analysis techniques. In this way industry can face both fresh opportunities and challenges, including predictive analysis using computer tools capable of detecting patterns in the data based on the same rules that can be used to formulate the prediction.

Miniaci Marco, Kherraz Nesrine, Cröenne Charles et al.

Large scale elastic metamaterials have recently attracted increasing interest in the scientific community for their potential as passive isolation structures for seismic waves. In particular, so-called “seismic shields” have been proposed for the protection of large areas where other isolation strategies (e.g. dampers) are not workable solutions. In this work, we investigate the feasibility of an innovative design based on hierarchical design of the unit cell, i.e. a structure with a self-similar geometry repeated at different scales. Results show how the introduction of hierarchy allows the conception of unit cells exhibiting reduced size with respect to the wavelength while maintaining the same or improved isolation efficiency at frequencies of interest for earthquake engineering. This allows to move closer to the practical realization of such seismic shields, where low-frequency operation and acceptable size are both essential characteristics for feasibility.

Ramses Sala

Research and development in computer technology and computational methods have resulted in a wide variety of valuable tools for Computer-Aided Engineering (CAE) and Industrial Engineering. However, despite the exponential increase in computational capabilities and Artificial Intelligence (AI) methods, many of the visionary perspectives on cybernetic automation of design, engineering, and development have not been successfully pursued or realized yet. While contemporary research trends and movements such as Industry 4.0 primarily target progress by connected automation in manufacturing and production, the objective of this paper is to survey progress and formulate perspectives targeted on the automation and autonomization of engineering development processes. Based on an interdisciplinary mini-review, this work identifies open challenges, synergies, and research opportunities towards the realization of resource-efficient cooperative engineering and development systems. In order to go beyond conventional human-centered, tool-based CAE approaches and realize Computational Intelligence Driven Development processes, it is suggested to extend the framework of Computational Rationality to challenges in design, engineering and development.

Michael Franklin Bosu, Stephen G. MacDonell

Context: The utility of prediction models in empirical software engineering (ESE) is heavily reliant on the quality of the data used in building those models. Several data quality challenges such as noise, incompleteness, outliers and duplicate data points may be relevant in this regard. Objective: We investigate the reporting of three potentially influential elements of data quality in ESE studies: data collection, data pre-processing, and the identification of data quality issues. This enables us to establish how researchers view the topic of data quality and the mechanisms that are being used to address it. Greater awareness of data quality should inform both the sound conduct of ESE research and the robust practice of ESE data collection and processing. Method: We performed a targeted literature review of empirical software engineering studies covering the period January 2007 to September 2012. A total of 221 relevant studies met our inclusion criteria and were characterized in terms of their consideration and treatment of data quality. Results: We obtained useful insights as to how the ESE community considers these three elements of data quality. Only 23 of these 221 studies reported on all three elements of data quality considered in this paper. Conclusion: The reporting of data collection procedures is not documented consistently in ESE studies. It will be useful if data collection challenges are reported in order to improve our understanding of why there are problems with software engineering data sets and the models developed from them. More generally, data quality should be given far greater attention by the community. The improvement of data sets through enhanced data collection, pre-processing and quality assessment should lead to more reliable prediction models, thus improving the practice of software engineering.

Yuan Liu, Xueju Wang, Yameng Xu et al.

Significance The 3D micro and nanostructures in advanced materials serve as the basis for emerging classes of 3D microsystems that have unusual function and/or enhanced performance, with potential applications in biomedical devices, energy storage systems, and elsewhere. The results presented here establish a fundamental understanding of various aspects of interface mechanics associated with routes to such 3D systems that exploit concepts similar to those in pop-up books, thereby allowing the construction of general design diagrams. Findings also indicate that these principles in interface mechanics can provide the basis for 3D mesostructures with reconfigurable geometries of relevance to morphing microdevices, such as micromechanical resonators, antennas, and optical modulators. Techniques for forming sophisticated, 3D mesostructures in advanced, functional materials are of rapidly growing interest, owing to their potential uses across a broad range of fundamental and applied areas of application. Recently developed approaches to 3D assembly that rely on controlled buckling mechanics serve as versatile routes to 3D mesostructures in a diverse range of high-quality materials and length scales of relevance for 3D microsystems with unusual function and/or enhanced performance. Nonlinear buckling and delamination behaviors in materials that combine both weak and strong interfaces are foundational to the assembly process, but they can be difficult to control, especially for complex geometries. This paper presents theoretical and experimental studies of the fundamental aspects of adhesion and delamination in this context. By quantifying the effects of various essential parameters on these processes, we establish general design diagrams for different material systems, taking into account 4 dominant delamination states (wrinkling, partial delamination of the weak interface, full delamination of the weak interface, and partial delamination of the strong interface). These diagrams provide guidelines for the selection of engineering parameters that avoid interface-related failure, as demonstrated by a series of examples in 3D helical mesostructures and mesostructures that are reconfigurable based on the control of loading-path trajectories. Three-dimensional micromechanical resonators with frequencies that can be selected between 2 distinct values serve as demonstrative examples.

L. Anand, S. Govindjee

Continuum mechanics of Solids presents a unified treatment of the major concepts in Solid Mechanics for beginning graduate students in the many branches of engineering. The fundamental topics of kinematics in finite and infinitesimal deformation, mechanical and thermodynamic balances plus entropy imbalance in the small strain setting are covered as they apply to all solids. The major material models of Elasticity, Viscoelasticity, and Plasticity are detailed and models for Fracture and Fatigue are discussed. In addition to these topics in Solid Mechanics, because of the growing need for engineering students to have a knowledge of the coupled multi-physics response of materials in modern technologies related to the environment and energy, the book also includes chapters on Thermoelasticity, Chemoelasticity, Poroelasticity, and Piezoelectricity. A preview to the theory of finite elasticity and elastomeric materials is also given. Throughout, example computations are presented to highlight how the developed theories may be applied.

Victor Maiboroda, Dmytro Dzhulii, Andrii Zelinko

Проблематика. В современном производстве возникает необходимость в финишной обработке поверхностей стальных деталей с нулевой и малой кривизной с целью снижения шероховатости и получения выглаженного микропрофиля. Актуальным является создание мобильного, универсального подвижно-скоординированного абразивного инструмента, обладающего широким спектром его использования на станках разных типов. Для этого необходимо провести исследования по влиянию не только типа магнитно-абразивного порошка, а и его формы и размеров на эффективность обработки плоских поверхностей головками торцевого типа с постоянными магнитами повышенной мощности, а и определить рациональные условия их эксплуатации. Цель исследования. Целью данной работы было определение эффективности процесса магнитно-абразивной обработки торцевыми головками на постоянных магнитах плоских ферромагнитных поверхностей магнитно-абразивными порошками различных типов, с разной формой частиц и величиной рабочего зазора. Методика реализации. Исследование выполняли на плоских образцах из стали 45 с предварительной их подготовкой торцевым фрезерованием и шлифованием. Их обработку выполняли головкой, на рабочем торце которой формируется магнитно-абразивный порошок в виде щетки, при разных рабочих зазорах. Результаты исследования. В работе приведены результаты исследований магнитно-абразивной обработки плоских поверхностей головками с постоянными высокомощными магнитами. При исследовании возможности использования разных по типу, форме и размерам частиц магнитно-абразивных порошков показано, что целесообразным является использование порошков с оскольчатой формой частиц с большим количеством режущих микрокромок на поверхности частиц и с малым радиусом их округления. Полученные результаты позволяют предположить, что процесс формирования магнитно-абразивного инструмента, непосредственно его форма и характер расположения магнитно-абразивных частиц и их групп по отношению к обрабатываемой поверхности будут оказывать существенное влияния на конечный результат обработки. Выводы. В результате экспериментальных исследований процесса магнитно-абразивной обработки плоских стальных поверхностей порошками различных типов и зернистости, показано возможность обеспечения шероховатости поверхности с Ra < 0,05 мкм с одновременным удалением волнистости поверхности. Установлено, что решающим технологическим ориентиром при достижении минимальной шероховатости является величина рабочего зазора, которая должна быть не меньше 1,5 мм.

Vinod Tamburi, Amba Shetty, S. Shrihari

Different methods of land use and management have a significant effect on soil properties distribution. Understanding of variations in soil nutrients in agricultural land use is important. An increase in extraction of nutrients, soil degradation, and management of nutrients is leading to a decline in quality of vertisols across the Deccan plateau of India. Though there are studies on spatial variability of vertisols macronutrients, studies on available calcium (Ca) and available magnesium (Mg) are rare. This study is conducted in Gulbarga taluk, north Karnataka, India, to evaluate the variability of soil pH, Ca, Mg, and Zinc (Zn). A total of 78 samples of soils are collected at 0 to 15 cm depth based on the accessibility and distribution of field patterns. Four subsamples represent a single composite sample. Agilent 4200 MP-AES (Microwave Plasma-Atomic. Emission Spectrometer) was used for determining the concentration of soil nutrients. The soil nutrients represent wide variation in coefficient of variation (CV) with a value of 6 % (for pH) to 70.9 % (for Zn). The soil pH showed a significantly positive correlation to Ca and a negative correlation to Mg. Geostatistical investigation indicates spherical model is the best fit for all nutrients. Except for Ca, all nutrients showed moderate spatial dependence. Ordinary kriging is used to generate spatial variability maps. The maps of spatial variability are highly variable in nutrients content and indicate that site-specific management needs to be taken by local authorities and improve the livelihood of marginal farmers and also for sustainable agriculture.

Ahmed T. Khalil, Dimitris M. Manias, Efstathios-Al. Tingas et al.

The dynamics of a homogeneous adiabatic autoignition of an ammonia/air mixture at constant volume was studied, using the algorithmic tools of Computational Singular Perturbation. Since ammonia combustion is characterized by both unrealistically long ignition delays and elevated NO<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mi>x</mi> </msub> </semantics> </math> </inline-formula> emissions, the time frame of action of the modes that are responsible for ignition was analyzed by calculating the developing time scales throughout the process and by studying their possible relation to NO<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mi>x</mi> </msub> </semantics> </math> </inline-formula> emissions. The reactions that support or oppose the explosive time scale were identified, along with the variables that are related the most to the dynamics that drive the system to an explosion. It is shown that reaction H<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>2</mn> </msub> </semantics> </math> </inline-formula>O<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>2</mn> </msub> </semantics> </math> </inline-formula> (+M) &#8594; OH + OH (+M) is the one contributing the most to the time scale that characterizes ignition and that its reactant H<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>2</mn> </msub> </semantics> </math> </inline-formula>O<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>2</mn> </msub> </semantics> </math> </inline-formula> is the species related the most to this time scale. These findings suggested that addition of H<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>2</mn> </msub> </semantics> </math> </inline-formula>O<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>2</mn> </msub> </semantics> </math> </inline-formula> in the initial mixture will influence strongly the evolution of the process. It was shown that ignition of pure ammonia advanced as a slow thermal explosion with very limited chemical runaway. The ignition delay could be reduced by more than two orders of magnitude through H<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>2</mn> </msub> </semantics> </math> </inline-formula>O<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>2</mn> </msub> </semantics> </math> </inline-formula> addition, which causes only a minor increase in NO<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mi>x</mi> </msub> </semantics> </math> </inline-formula> emissions.