Hasil untuk "Mechanics of engineering. Applied mechanics"

Hamid Nawaz, Naila Batool, Muhammad Tahir et al.

This Analysis of reviews became a valuable source of accurate information. In this research, we will analyze reviews. Analyzed reviews will create an accurate data set. Fitting an appropriate model is necessary to get accuracy. Problems in fitting an appropriate model are under-fitting and over-fitting. An under-fit model will be less flexible and cannot account for the data. Over-fitting is a modeling error that occurs when a function is too closely fit to a limited set of data points. To solve the mentioned problems, features and appropriate algorithms are selected. As a solution, we will perform preprocessing in a better way with the machine learning algorithms to assess the impact of preprocessing. The main focus of this research is to assess the impact of preprocessing steps on different classifiers.

Saravanan Sekaran, Dhanraj Ganapathy, Deepavalli Arumuganainar et al.

India bears the highest global burden of oral cancer, with over 83,400 cases reported in 2022. The widespread use of smokeless tobacco and areca nut, particularly in rural and underserved communities, continues to drive this public health crisis. Despite government regulations and awareness campaigns, tobacco consumption remains high due to cultural acceptance, affordability, and accessibility of products like gutkha and khaini. This review examines the role of celebrity endorsements in tobacco cessation efforts, assessing their influence on public perception and behavior. Bollywood actors and sports icons, who hold immense cultural influence in India, have been leveraged in health campaigns to promote tobacco-free lifestyles. While some celebrity-driven initiatives have successfully raised awareness, surrogate marketing remains a critical challenge. Many celebrities indirectly endorse harmful products like pan masala and mouth fresheners, undermining tobacco control efforts. To counter this, stricter policies are needed to regulate celebrity endorsements, ensuring alignment with public health goals. This review highlights key strategies for maximizing the impact of celebrity-led health campaigns while minimizing the risks posed by surrogate marketing. By fostering sustained celebrity engagement and implementing robust policy measures, India can take significant steps toward reducing smokeless tobacco use and preventing oral cancer.

Konstantinos-Panagiotis Bouzoukis, Georgios Moraitis, Vassilis Kostopoulos et al.

The proliferation of CubeSats in Earth orbit has accelerated dramatically in recent years, with projections indicating continued growth in the coming decades. This review examines the evolution of CubeSat applications, from basic technology demonstrations to complex mission capabilities, including Earth observation, telecommunications, astronomical research, biological experimentation, and deep-space exploration. A notable shift has occurred over the past fifteen years, with CubeSats transitioning from standalone platforms to integrated nodes within larger constellations, particularly for Earth observation and telecommunications applications. We analyze the key enabling factors behind the CubeSat revolution, including decreased launch costs, miniaturized electronics, standardized components, and institutional support frameworks. Through the examination of significant past, current, and planned missions, this paper provides a comprehensive overview of CubeSat capabilities across diverse application domains. The review highlights how these miniaturized satellite platforms are democratizing access to space while enabling innovative scientific and commercial applications previously restricted to larger spacecraft.

Vishwas Mahesh

This study focuses on the mechanical characterization and application of the various Multiple Attribute Decision Making (MADM) approaches for the selection of composites fabricated using two natural fibers, kenaf, and sawdust. Mechanical characterization involves testing the physical properties of these materials, such as tensile strength, flexural strength, and impact strength along with density and water absorption, to determine their mechanical behavior and suitability for various applications. The MADM approaches namely VIKOR and PSI are used to evaluate the mechanical properties of kenaf and sawdust reinforced composites for different applications based on multiple criteria or attributes. The study analyzes the trade-offs between different attributes to identify the optimal composite configuration for a given application. MADM technique offers a helpful framework for assessing the mechanical attributes of fiber-reinforced composites thereby determining their possible uses in a variety of sectors. However, it is essential to use the MADM approach in conjunction with other methods of material characterization and testing to ensure that the final decision is based on a comprehensive understanding of the material's properties and performance. The outcomes of this feasibility study will benefit researchers, manufacturers, and decision-makers involved in the selection and development of composite materials. It can assist in optimizing the material selection process, promoting sustainable and environmentally friendly choices, and enhancing the overall performance and cost-effectiveness of composite materials in various applications.

Jullyanne Silva, Tiago Atalaia, João Abrantes et al.

According to the World Health Organization, one-third of elderly people aged 65 or over fall annually, and this number increases after 70. Several gait biomechanical parameters were associated with a history of falls. This study aimed to conduct a systematic review to identify and describe the gait biomechanical parameters related to falls in the elderly. MEDLINE Complete, Cochrane, Web of Science, and CINAHL Complete were searched for articles on 22 November 2023, using the following search sentence: (gait) AND (fall*) AND ((elder*) OR (old*) OR (senior*)) AND ((kinematic*) OR (kinetic*) OR (biomechanic*) OR (electromyogram*) OR (emg) OR (motion analysis*) OR (plantar pressure)). This search identified 13,988 studies. From these, 96 were selected. Gait speed, stride/step length, and double support phase are gait biomechanical parameters that differentiate fallers from non-fallers. Fallers also tended to exhibit higher variability in gait biomechanical parameters, namely the minimum foot/toe clearance variability. Although the studies were scarce, differences between fallers and non-fallers were found regarding lower limb muscular activity and joint biomechanics. Due to the scarce literature and contradictory results among studies, it is complex to draw clear conclusions for parameters related to postural stability. Minimum foot/toe clearance, step width, and knee kinematics did not differentiate fallers from non-fallers.

Milan Sapieta, Vladimír Dekýš, Michal Kaco et al.

The work aims at validating a methodology for 3D printing of gears with involute gearing and evaluating their mechanical properties using infrared camera. A general methodology for the setup of 3D printing of gears made of polymeric materials has been developed, which can be used in technical practice in order to replace parts produced by conventional methods. An experiment was prepared determination of the distribution of the 1st invariant of the stress tensor and phase shift using a modal exciter and an IR camera. The values of the 1st invariant of the stress invariant were found. For these measurements, the lock-in thermography method was used, using a modal exciter we force loaded a gear in which the response to the load was registered. The aim was to obtain the distribution of the strain or stress field on the loaded tooth. The experimental method used also belongs to the field of non-destructive testing (NDT), and with suitable experimental parameters we can also obtain information from the layers below the surface, as demonstrated in the phase images. The practical benefit is to provide a competitive advantage to companies that will exploit the properties of polymeric materials by knowing the mechanical properties of these materials.

Zhibin Yu

Janusz Piechna

Compression by shock waves is a specific way of compressing gases. It has been practically applied for many years in supersonic flying objects. The idea of using this method in rotary engines is extremely appealing because one disk can replace several or a dozen disks of an axial compressor, significantly reducing the weight and production costs of the engine and lowering the fuel consumption due to possible increased compression ratio. This paper presents a review of existing technical solutions and the results of published research devoted to the construction of shock wave compression rotary engines: patents, scientific publications describing various research methods, numerical calculations, and the experimental results of unusual technical solutions. The characteristic solutions and problems that arose during the implementation of these methods are presented and described. Judging from the presented overview, these have wide application possibilities, and an enormous intellectual and financial effort has been put into the construction of such engines. Conversely, there is a rather hermetic group of scientists involved in this activity.

Thomas Kivevele

Most of the food transport trucks in Sothern Africa are equipped with refrigeration and air conditioning systems filled with fluorocarbon refrigerants such as R404A to facilitate the heat transfer process. These refrigerants are synthetic chemicals and have high potential to cause global warming and damage to the ozone layer. Currently, natural refrigerants are considered as alternatives to these man-made refrigerants to mitigate some of the environmental risks. The natural refrigerants are the substances that occur in nature such as hydrocarbons (HC), ammonia, and carbon dioxide. These type of refrigerants have been in the market for many years, but in some applications such as domestic refrigerators, heat pumps, chillers, and air conditioners, whereas fluorocarbons are the mostly used in the food transport refrigeration systems. Natural refrigerants such as propane (HC – 290) are now penetrating the market in food transport refrigeration systems where previously fluorocarbons were the favoured option. Therefore, this work reports the possibilities of using non-fluorinated hydrocarbon/natural refrigerant (propane – R290) in the food transport refrigerated systems in Southern Africa; a case study of South Africa. R290 has the potential to lower greenhouse gases emissions compared to hydrofluorocarbons (HFCs) which are widely used in most of the existing food transport refrigeration systems in South Africa. R290 has negligible Global Warming Potential (GWP) of 3 which is well below the global threshold value of 150. The review revealed that refrigeration capacity of R290 is in the average of 10 – 30% higher than commonly used fluorocarbon refrigerants such as R404A and R134A. Since R290 is labeled as a flammable refrigerant, the present study also reviews its flammability safety measures.

Iwona Zaborowska, Hubert Grzybowski, Romuald Mosdorf

In the paper, a self-organizing map combined with the recurrence quantification analysis was used to identify flow boiling patterns in a circular horizontal minichannel with an inner diameter of 1 mm. The dynamics of the pressure drop during density-wave oscillations in a single pressure drop oscillations cycle were considered. It has been shown that the proposed algorithm allows us to distinguish five types of non-stationary two-phase flow patterns, such as bubble flow, confined bubble flow, wavy annular flow, liquid flow, and slug flow. The flow pattern identification was confirmed by images obtained using a high-speed camera. Taking into consideration the oscillations between identified two-phase flow patterns, the four boiling regimes during a single cycle of the long-period pressure drop oscillations are classified. The obtained results show that the proposed combination of recurrence quantification analysis (<i>RQA</i>) and a self-organizing map (<i>SOM</i>) in the paper can be used to analyze changes in flow patterns in non-stationary boiling. It seems that the use of more complex algorithms of neural networks and their learning process can lead to the automation of the process of identifying boiling regimes in minichannel heat exchangers.

Vinícius Torres Pinto, Luiz Alberto Oliveira Rocha, Cristiano Fragassa et al.

Constructal design, finite element method and exhaustive search are applied to analyze different arrangements of steel plates with rectangular or trapezoidal stiffeners. As performance parameters, the maximum deflection and maximum von Mises stress are considered. A non-stiffened plate adopted as reference is studied together with 25 plates with rectangular stiffeners and 25 plates with trapezoidal stiffeners. The results show that trapezoidal stiffeners are more effective in minimizing the maximum deflection in comparison with rectangular stiffeners. However, regarding the minimization of stress, the rectangular stiffeners normally present better performance. When both performance parameters are concomitantly considered, a slight advantage of 4.70% for rectangular geometry is identified.

Andrey K. Tugengold

The strategic approach to the development of the intellectual control systems of the machine tool accuracy as mechatronic technological systems is presented. It is based on the present-day ideas in the field of the error formation, processing accuracy control with the use of GKM capabilities and electronic manufacturing facilities documentation.

Nurzhagan N. Kazieva

Some current questions of the labour productivity increase in the business area through the optimal personnel recruitment and management are considered. Some effective techniques of the recruitment policy are described. A psychological model of the personnel development is offered.

Sh. Vahedi, S.M.H. Siadati, H. Khosravi et al.

The effects of surface-functionalized Na+-montmorillonite nanoclay particles on the flexural behavior of E-glass fiber-reinforced aluminum (GLARE) laminates were investigated. The nanoclay particles were subjected to surface functionalization using 3-(trimethoxysilyl)propylamine to increase their compatibility with the epoxy matrix and improve their dispersion within the matrix. Experimental results indicated that the GLARE laminates achieved the highest flexural strength (61%) and energy absorption (51%) at an addition of 3 wt% functionalized nanoclay. The highest flexural modulus (67% increase) was observed at an addition of 5 wt% functionalized nanoclay. The flexural properties of the functionalized nanoclay-filled GLARE laminates were significantly better than those of untreated nanoclay-filled GLARE laminates. Microscopic observations suggested that the introduction of functionalized nanoclay particles markedly enhanced the interfacial adhesion between the matrix and the E-glass fibers.

Hanan Mikhael Dawood

Economic dispatch (ED) in power system is one of important optimization problems for determining and providing an economic condition for generation units. The nonlinearity of this problem makes conventional methods unable to determine a fast and robust solution, especially when the power system contains the highest number of generation units. In this paper, optimization technique called Artificial Bee Colony (ABC) is used to solve economic dispatch problem in power system. ABC based on the behavior of bees to search for food sources. The obtained results are compared with the conventional method using test system. It shows that the ABC algorithm approach is more feasible and efficient for finding minimum cost. Therefore, ABC approach has been applied for Iraqi National Grid. The proposed methods are executed in MATLAB environment

Y. Rostamiyan, M. Abbasi, F. Aghajani et al.

In the age of technology, it is vital to cool down different parts of a device to use it more beneficially. Using nanofluids is one of the most common methods which has shown very effective results. In this paper, we have rephrased a classic equation in fluid mechanics, i.e. the Falkner-Skan boundary layer equation, in order to be used for nanofluid. This nonlinear equation, which was presented by Liao, has been solved by Homotopy Analysis Method (HAM). This method is very capable to solve a wide range of nonlinear equations. The physical interpretation of results which are velocity and temperature profiles are explained in details and they are parallel with experimental outcomes of previous researchers.

Dvořák R.

The aim of this paper is to show the significance of vortices in animal locomotion in fluids on two deliberately chosen examples. The first example concerns lift generation by bird and insect wings, the second example briefly mentiones swimming and walking on water. In all the examples, the vortices generated by the moving animal impart the necessary momentum to the surrounding fluid, the reaction to which is the force moving or lifting the animal.

Hayder Abd Al-kaream Muhsin

The main object of this study is to investigate the influence of column diameter and superficial gas velocity on liquid phase dispersion coefficients (axial and radial dispersion coefficients), mixing times, gas holdup, and bubble dynamics (bubble diameter and rise velocity). The liquid phase dispersion, gas holdup, and bubble dynamics (Db and Vb0) were measured for the air-water system in bubble columns of two different diameters,15 and 30 cm. The superficial gas velocity, Ug, was varied in the range 1-10 cm/s, spanning both the homogeneous and heterogeneous flow regimes. The height of liquid in the column was kept constant at 130 cm for the two column. Axial and radial dispersion coefficients and mixing times were measured at various axial and radial locations inside the columns (Z = 25, 75, 125 cm and r/R = 0, 0.45, 0.85), bubble dynamics were measured at three axial location (Z=25, 75, 125 cm). From the experimental data it was found that, the value of the radial dispersion coefficient (Dr,L) and axial dispersion coefficient (Dax,L), gas holdup, bubble diameter and bubble rise velocity, increase with increasing superficial gas velocity. The results emphasise the significant influence of the column diameter on the hydrodynamics. Gas holdup showed a decrease with increasing column diameter, while the radial dispersion coefficient (Dr,L), axial dispersion coefficient (Dax,L), bubble diameter and bubble rise velocity increased with increasing column diameter.  A statistical analysis was performed to get a general correlations for the axial liquid dispersion coefficient as a function of the mixing time and dispersion height (Hd), this correlations are: Dax,L=0.15 H2d /θ0.3 for 30 cm column diameter and Dax,L=0.11 H2d /θ0.3 for 15 cm column diameter.

Masahiko SHIBAHARA, Shin-ichi SATAKE, Jun TANIGUCHI

In the present study the quantum molecular dynamics method was applied to an energy transfer problem to an electron during ionic surface collision process in order to elucidate how energy of ionic collision transfers to the emitted electrons. Effects of various physical parameters, such as the collision velocity and interaction strength between the observed electron and the classical particles on the energy transfer to the electron were investigated by the quantum molecular dynamics method when the potassium ion was collided with the surface so as to elucidate the energy path to the electron and the predominant factor of energy transfer to the electron. Effects of potential energy between the ion and the electron and that between the surface molecule and the electron on the electronic energy transfer were shown in the present paper. The energy transfer to the observed secondary electron through the potential energy term between the ion and the electron was much dependent on the ion collision energy although the energy increase to the observed secondary electron was not monotonous through the potential energy between the ion and surface molecules with the change of the ion collision energy.

Amir Masoud Rahimi

Abstract This paper proposed an integrated algorithm of neuro-fuzzy techniques to examine the complex impact of socio-technical influencing factors on road fatalities. The proposed algorithm could handle complexity, non-linearity and fuzziness in the modeling environment due to its mechanism. The Neuro-fuzzy algorithm for determination of the potential influencing factors on road fatalities consisted of two phases. In the first phase, intelligent techniques are compared for their improved accuracy in predicting fatality rate with respect to some socio-technical influencing factors. Then in the second phase, sensitivity analysis is performed to calculate the pure effect on fatality rate of the potential influencing factors. The applicability and usefulness of the proposed algorithm is illustrated using the data in Iran provincial road transportation systems in the time period 2012-2014. Results show that road design improvement, number of trips, and number of passengers are the most influencing factors on provincial road fatality rate.