Hasil untuk "Mechanical engineering and machinery"

Mohammed A. N Ali, Labed Kadhim Jawad, Ahmed Ibrahim Razooqi

This research studied experimentally the behavior of an aluminum alloy 7050 thin plate containing different sizes of circular central holes under thermo-mechanical fatigue crack growth testing. Transient thermal cyclic loading from 50℃ to 200℃ where applied, combined with constant tensile mechanical load at 200 kg at the edge of the plate. Three cases were experimentally tested based on the hole diameter of (1, 2, 3 mm) under the same testing conditions. Results show the increment of central hole diameter makes the crack initiation start earlier and crack growth increases then goes faster. Also, it has increased the stress intensity. The length of the second region of crack propagation related to stress intensity decreased when the hole size increased, and the slope changed too. For that, different Paris laws were obtained based on the central hole size. Accordingly, to these Paris laws, it can be easily informed and analyzed the behavior of any engineering structure made of this type of alloy under the same loading condition and predict its fracture or failure limits or lives.

Babangida Modu, Md Pauzi Abdullah, Abdulrahman Alkassem et al.

The study addresses the integration of hybrid hydrogen (H2) and battery (BT) energy storage systems into a renewable energy microgrid comprising solar photovoltaic (PV) and wind turbine (WT) systems. The research problem focuses on improving the effectiveness and computational efficiency of energy management systems (EMS) while ensuring high system reliability. Despite the existing optimization methods for hybrid microgrids, challenges remain in optimizing energy storage and capacity planning in grid-connected microgrids. To solve this, we propose the use of the Levy Flight Algorithm (LFA) to optimize the capacities of PV, WT, H2 tanks, electrolyzers (EL), fuel cells (FC), and BT, which presents a complex nonlinear optimization challenge. The novelty of this study lies in integrating the LFA with a rule-based EMS, enhancing system reliability and efficiency. The proposed approach significantly reduces the annualized system cost (ASC) and the levelized cost of energy (LCOE). The result demonstrate that the LFA outperforms methods like the Salp Swarm Algorithm (SSA), Particle Swarm Optimization (PSO), Grey Wolf Optimization (GWO) and Genetic Algorithm (GA), yielding cost savings of $3,309, $5,297, $4,484, and $5,129 respectively. The LFA achieves the lowest LCOE at $0.275/kWh, compared to $0.278/kWh with SSA, $0.289/kWh with GA, $0.280/kWh with PSO and $0.283/kWh with GWO. This research contributes to the broader scientific community by providing a more efficient approach to optimizing renewable energy microgrids with hybrid storage systems, thus promoting eco-friendly and cost-effective energy solutions. The proposed system design offers a pathway to future energy systems with high renewable integration, especially as technology advances and costs continue to decrease.

Sudong Kim, Marina Uroz, Jennifer L. Bays et al.

A primary challenge in tissue engineering is to recapitulate both the structural and functional features of whole tissues and organs. In vivo, patterning of the body plan and constituent tissues emerges from the carefully orchestrated interactions between the transcriptional programs that give rise to cell types and the mechanical forces that drive the bending, twisting, and extensions critical to morphogenesis. Substantial recent progress in mechanobiology-understanding how mechanics regulate cell behaviors and what cellular machineries are responsible-raises the possibility that one can begin to use these insights to help guide the strategy and design of functional engineered tissues. In this perspective, we review and propose the development of different approaches, from providing appropriate extracellular mechanical cues to interfering with cellular mechanosensing machinery, to aid in controlling cell and tissue structure and function.

L. Kumawat, H. Raheman

Abstract The knowledge of the engineering properties of the onion bulb is a prerequisite to designing machinery for harvesting and post-harvest operations. The agronomical, mechanical, and biometric properties of the onion crop were measured for the Pusa Red variety at the harvesting stage. Onion (Allium cepa L.) seedlings of Pusa Red variety were grown at 150-mm row-to-row and 100-mm plant-to-plant spacing in sandy loam soil. The onion bulbs were obtained within 69.15 ± 7.17 mm below the ground surface with a coefficient of variation (CV) of 10.37%. The average length of onion plants was found to be 236.5 ± 35.28 mm with a CV of 14.91%. The cutting force required to cut the leaves from the onion was in the range of 45.42–105.87 N. The pulling force required to dig out the bulbs at the mean depth of 70 mm was found to be 32.33 ± 3.05 N. The shape of Pusa Red onion bulbs was found to be of prolate shape. The average values of polar diameter, equatorial diameter, and mass for the large onion bulbs were found to be 57.83 ± 5.26 mm, 46.88 ± 3.29 mm, and 65.68 ± 4.22 g, respectively, as compared to 47.44 ± 2.46 mm, 43.81 ± 3.33 mm, and 47.51 ± 7.07 g, for small onion bulbs. The average value of bulk density for the large and small onion bulbs was found to be 403 and 501.33 kg m−3, respectively. The mean value of angle of repose for small-size bulbs was obtained at 29.2°. A linear relationship was found to exist between polar and equatorial diameters as well as the mass of the bulb and polar/equatorial diameter for both large and small size onion bulbs.

Adrian Cubillo, Suresh Perinpanayagam, Manuel Esperon-Miguez

Health condition monitoring for rotating machinery has been developed for many years due to its potential to reduce the cost of the maintenance operations and increase availability. Covering aspects include sensors, signal processing, health assessment and decision-making. This article focuses on prognostics based on physics-based models. While the majority of the research in health condition monitoring focuses on data-driven techniques, physics-based techniques are particularly important if accuracy is a critical factor and testing is restricted. Moreover, the benefits of both approaches can be combined when data-driven and physics-based techniques are integrated. This article reviews the concept of physics-based models for prognostics. An overview of common failure modes of rotating machinery is provided along with the most relevant degradation mechanisms. The models available to represent these degradation mechanisms and their application for prognostics are discussed. Models that have not been applied to health condition monitoring, for example, wear due to metal–metal contact in hydrodynamic bearings, are also included due to its potential for health condition monitoring. The main contribution of this article is the identification of potential physics-based models for prognostics in rotating machinery.

Núria Boix Rodríguez, Fabrizio Moroni, A. Lutey et al.

G. Brodie

Agricultural engineering (AGEN) is one of two engineering degree programs offered in the Department of Biological Systems Engineering. AGEN students emphasize coursework in one of three engineering areas; machine design, test, or soil and water resources. Thus, some agricultural engineers are involved in the analysis and design of field machinery systems and machine components through study of the principles of mechanical design, joining techniques, hydraulics, controls, ergonomics, and safety. Others are evaluating machine or mechanical system functional performance based on study of test procedure standards, measurements, data acquisition, electronic communication and statistics, and practical experience gained at the Nebraska Tractor Test Laboratory. Still others are analyzing and designing soil and water management-related infrastructure as aided through study of irrigation, drainage, erosion and runoff control techniques, crop tillage and cultivation practices and natural resources management. Job opportunities for graduates are available in industry, public agencies, consulting, and private practice.

Rita Ferreira, Óscar Carvalho, Luís Sobral et al.

Abstract The radial surface coating layer of compression piston rings is used to improve their wear resistance during the internal combustion engine operation. However, at top dead centers, the friction coefficient of the piston ring-cylinder liner pair is detrimental to the engine’s tribological performance. In this work, dimples with different texture dimensions and densities were tested in a home-developed tribometer. The friction coefficient was measured for all samples, and for those with the best results, their wear resistance was assessed. The texture with an aspect ratio of 0.25 and a density area of 15% reported the best tribological results.

Lei Chen, Yunchen Yu, Jie Luo et al.

The vehicle dynamics model has multiple degrees of freedom, with strong nonlinear characteristics, so it is difficult to quickly obtain the accurate target oil pressure of an electronically assisted brake system based on the model. This paper proposes a target oil pressure recognition algorithm based on the T-S fuzzy neural network model. Firstly, the braking conditions classification algorithm is built according to the sampled braking intention data. The data are divided into the emergency braking condition data and the general braking condition data by the braking conditions classification algorithm. Secondly, the recognition model is trained respectively by the different braking condition data sets. In the training process, the fuzzy C-means clustering algorithm is used to identify the antecedent parameters of the model, and the learning rate cosine attenuation strategy is applied to optimize the parameter learning process. Finally, a correction method of target oil pressure based on slip ratio is proposed, and the target oil pressure derived following control methods based on traditional PID and fuzzy PID are compared through experiments. The results show that the mean square error of oil pressure following control based on fuzzy PID is smaller, which proves that the proposed method is able to precisely control braking force.

Hsiao-Mei Lin, Ching-Yuan Lin, Chun-Hung Wang et al.

For fault diagnosis, convolutional neural networks (CNN) have been performing as a data-driven method to identify mechanical fault features in forms of vibration signals. However, because of CNN’s ineffective and inaccurate identification of unknown fault categories, we propose a model based on transfer learning with probability confidence CNN (TPCCNN) to model the fault features of rotating machinery for fault diagnosis. TPCCNN includes three major modules: (1) feature engineering to perform a series of data pre-processing and feature extraction; (2) transferring learning features of heterogeneous datasets for different datasets to have better generality in model training and reduce the time for modeling and parameter tuning; and (3) building a PCCNN model to classify known and unknown fault categories. In addition to solving the problem of an imbalanced sample size, TPCCNN self-learns and retrains by iterating with unknown classes to the original model. This model is verified with the use of the open-source datasets CWRU and Ottawa. The experimental results showing the feature transfer of heterogeneous datasets are of average accuracy rates of 99.2% and 93.8% respectively for known and unknown categories, and TPCCNN is then proven effectively in training heterogeneous datasets. Likewise, similar feature sets can also be applied to reduce the training of predicting models by 34% and 68% of the time.

Will Barnett, Ana Cavalcanti, Alvaro Miyazawa

The need for robotic systems to be verified grows as robots are increasingly used in complex applications with safety implications. Model-driven engineering and domain-specific languages (DSLs) have proven useful in the development of complex systems. RoboChart is a DSL for modelling robot software controllers using state machines and a simple component model. It is distinctive in that it has a formal semantics and support for automated verification. Our work enriches RoboChart with support for modelling architectures and architectural patterns used in the robotics domain. Support is in the shape of an additional DSL, RoboArch, whose primitive concepts encapsulate the notion of a layered architecture and architectural patterns for use in the design of the layers that are only informally described in the literature. A RoboArch model can be used to generate automatically a sketch of a RoboChart model, and the rules for automatic generation define a semantics for RoboArch. Additional patterns can be formalised by extending RoboArch. In this paper, we present RoboArch, and give a perspective of how it can be used in conjunction with CorteX, a software framework developed for the nuclear industry.

Eduardo Benítez Sandoval, Ricardo Sosa, Ricardo Sosa et al.

Creativity in social robots requires further attention in the interdisciplinary field of human–robot interaction (HRI). This study investigates the hypothesized connection between the perceived creative agency and the animacy of social robots. The goal of this work is to assess the relevance of robot movements in the attribution of creativity to robots. The results of this work inform the design of future human–robot creative interactions (HRCI). The study uses a storytelling game based on visual imagery inspired by the game “Story Cubes” to explore the perceived creative agency of social robots. This game is used to tell a classic story for children with an alternative ending. A 2 × 2 experiment was designed to compare two conditions: the robot telling the original version of the story and the robot plot twisting the end of the story. A Robotis Mini humanoid robot was used for the experiment, and we adapted the Short Scale of Creative Self (SSCS) to measure perceived creative agency in robots. We also used the Godspeed scale to explore different attributes of social robots in this setting. We did not obtain significant main effects of the robot movements or the story in the participants’ scores. However, we identified significant main effects of the robot movements in features of animacy, likeability, and perceived safety. This initial work encourages further studies experimenting with different robot embodiment and movements to evaluate the perceived creative agency in robots and inform the design of future robots that participate in creative interactions.

Xusheng Xue, Li Man, Xiangang Cao et al.

The ability of college students to discover, propose and solve engineering problems in machinery has become an essential part of a contemporary college education. Therefore, the teaching reform focusing on cultivating College Students’ ability to propose and solve engineering problems has become an essential part of a college education. Taking mechanical students as an example, this paper constructs a teaching content and method with “students” and “theory, engineering” as the double centres, combined with “pre-class”, “in-class” and “after class”, in which the teacher put forward the relationship between curriculum knowledge points and mechanical engineering problems, guide students to discover actively, learn and apply curriculum knowledge points, and put forward practical solutions to engineering problems in combination with mechanical engineering related issues. To achieve the goal of teaching engineering problems based on theoretical knowledge and practical operation, we should combine the “Internet plus” modern teaching tools to create “Online & Offline” mixed interactive courses and high-quality curriculum resources, forming the circular multi-dimensional closed-loop teaching mode of “student, theory, engineering” cycle, “pre-class, during-class, after-class” cycle and “before class test, instruction, after class test” cycle, which the students’ ability to master knowledge points in the teaching process.

E. Ferhatoglu, S. Zucca

ABSTRACT Wedge dampers are commonly used to utilize the frictional behavior in many engineering fields such as vehicle dynamics and turbo-machinery. However, the presence of non-unique contact forces in the damper interfaces creates an uncertainty that provides different dynamic response amplitudes even for the same input parameters. The maximum limits of the variability range always take the core attention in most of the damper design processes. In this paper, determination of an upper and a lower boundary among multiple steady-state solutions is presented by using a numerical approach. The method is specifically suitable for the mechanical systems with wedge dampers modeled by macro-slip frictional contact elements in the joint interfaces. In the approach proposed, a criterion that determines the periodic response boundaries according to the limit tangential force values is utilized. The method is demonstrated by illustrating several case studies on a lumped parameter system which represents a turbo-machinery application with a symmetric wedge damper pressed against two vibrating adjacent blades. A point-to-point 1D friction model with varying normal force is used in both contact sides. A parametric investigation on the variability range and response limits is performed for different damper configurations. Harmonic Balance Method with Newton's iteration scheme is used in the numerical solution of the governing equations. The results show that a large variability exists for damper geometries where a strong coupling is present between tangential and normal contact forces. The method proposed successfully captures the limits of the variability range in all cases.

L. Niu, Shufen Li, Yabin Zhu et al.

Abstract The zirconia toughened alumina (ZTA) composites have been widely used as an engineering material in many application areas due to their remarkable mechanical properties. However, the fracture toughness of ZTA does not generally meet the requirements of aerospace, machinery and other fields. In this study, the SiC whiskers (SiCw) have been incorporated in the ZTA composites to improve the fracture toughness. The SiCw employed in this study mainly consist of the β phase, with a small fraction of the α phase. The effect of the SiCw content and sintering temperature on the microstructure and mechanical properties of the SiCw-ZTA (ZASw) composites has been systematically studied. The incorporation of SiCw is noted to reduce the density of the ZASw composites. On enhancing the SiCw content, the Vickers hardness and fracture toughness of the composites initially decrease, followed by an increase. However, the flexural strength of the composites increases with the SiCw content. At a SiCw content of 10.0 vol.%, the strength, hardness and toughness are observed to reach the maximum values. On enhancing the sintering temperature, the strength and hardness of the composites are observed to remain nearly constant, while the toughness of the composites is increased.

T. Mashiyane, Dawood Desai, L. Tartibu

N. Dubrovina

The pace of innovative development of the machine-building complex and its structural changes are largely determined by the processes of automation, digitalization, improvement of machinery and equipment. Thepresented article discusses innovative technologies in mechanical engineering. The main trends in the innovative development of industrial production are: development of high-tech foreign economic activity, formation of an innovative space, digitalization of economy, creation of a unified database of innovative developments, formation of a new scientific base working on solving urgent problems, creation of markets for innovative products. It is determined that at all stages of the product life cycle, digital technologies are included, such as virtual reality, additive manufacturing, the industrial Internet of things, and a virtual trading platform. The definition of innovative and technological development of the machine-building complex is given. Despite the fact that innovative technologies ensure efficiency, agility and cost-effectiveness of production, in Russia the digital transformation process is in its infancy and is a promising necessity for the development of all industrial production. The transition to digital production technologies is associated with the solution of a number of problems. Such as modernization of the material and technical base, training and advanced training of personnel, preparation of the legislative framework, standardization, certification of innovative digital production technologies, search for investment resources.

Rupendra Kumar Pachauri, Jianbo Bai, Isha Kansal et al.

Abstract Large size photovoltaic (PV) systems face a large number of issues based on malfunction and unfavourable climatic conditions such as partial shading conditions (PSCs). These PSCs are the major causes of PV systems’ performance degradation. In this paper, a symmetric matrix (SM) game puzzle is used to reconfigure the electrical connections of the PV array system. Present shade dispersion methodology is based on the ‘physical reallocation of PV module‐fixed electrical connections’ principle. Modification in the electrical connections of conventional total cross‐tied (TCT) PV array configuration introduces a new ‘SM‐TCT’ configuration. An extensive comparative study of conventional TCT and novel‐TCT (NTCT) configurations with proposed SM‐TCT configuration prove the effectiveness to achieve higher performance. The MATLAB/Simulink results are obtained on the basis of the non‐linear nature of current‐voltage and power‐voltage characteristics. SM‐TCT, Shape‐do‐Ku, NTCT and TCT configurations are examined under three realistic PSCs in terms of power and voltage at global maximum power point, improved fill factor, reduced power losses, performance ratio and power enhancement.

Yuantao Gu, Quan Wan, Xiaoxia Li

Low-pressure N 2 adsorption (LPNA) could provide quantitative data for characterizing the pores in gas shale. However, the inconsistencies of outgas temperature have caused significant deviations in LPNA experiments. To explore the effects of outgas temperature on pore characteristics, two shale samples of Lower Cambrian Niutitang formation from Northern Guizhou, China, were collected for LPNA experiments and thermogravimetry-fourier transform infrared (TG-FTIR) spectroscopy. The samples were outgassed at six temperatures: 80°C, 100°C, 150°C, 200°C, 250°C, 300°C. Larger adsorbed volumes were presented in the isotherms at higher outgas temperatures. Similar regularity is obtained from the relationship between specific surface area, micropore volume and outgas temperature. Comprehensive analysis of TG-FTIR and LPNA at different outgas temperature indicated that at lower outgas temperatures (from 80°C to 100°C), the free water was unlikely to be removed completely, and resulted in large amounts of micropores couldn’t be accessed. An excessive outgas temperature might expulse liquid hydrocarbons or decompose organic matter (from 200°C to 300°C), and could lead to the generation of micropores. When the sample were outgassed at 150°C, TG-FTIR analysis indicated that the sample composition unchanged and a better removal of free water happened. Therefore, 150°C should be a suitable outgas temperature for shale in LPNA experiments. The findings in this research not only provide reliable evidence for the selection of outgas procedure in LPNA for shale, but clarify the important effects of free water and volatile materials on pore accessibility in shale.

Sai Zhang, Zicheng Li, Hou‐Neng Wang et al.

Abstract A fractional order sliding mode control (FOSMC) based on single parameter adaptive law for nano‐positioning of Piezoelectric Actuators (PEAs) is proposed. First, the Bouc–Wen (B–W) model is used to describe the hysteresis of the nano‐position platform based on PEAs, which provides a mathematical model for the subsequent controller design. Then, theoretical support is provided to design the FOSMC based on adaptive law of different parameters, which are proposed for the displacement tracking problem of PEAs, and the position error convergence is also proved. Moreover, the core parameters of FOSMC based on single parameter adaptive law are identified by hybrid differential evolution (HDE) and adaptive differential evolution (ADE), which require considering the relationship between the scaling factor and the cross‐probability factor. Finally, experiments have been conducted with the displacement signals mixed with multiple frequencies and multiple amplitudes and the results obtained from them show that the proposed control scheme can produce a faster response and smaller tracking errors in PEAs system as compared to traditional control algorithms.