Engineering Science and Technology-An International Journal-Jestech最新文献

In this paper, a kind of superconductor ceramics metastructure-photonic crystals (SCMPC) is proposed to investigate the absorption and transmission properties of electromagnetic waves (EW) by combining a metastructure with multiple degrees of freedom regulation and strong energy localization characteristics of photonic crystals. Firstly, for the periodically aligned SCMPC, EW mainly realizes absorption in forward propagation and transmission in backward case. The relative bandwidth (RB) for both forward absorptivity and backward transmittance greater than 0.9 is 2.7 %, and the operating bandwidth (OB) is 696 ∼ 715 terahertz (THz), which is an asymmetric absorption-transmission (AAT) characteristics. Importantly, the periodically aligned SCMPC can realize the double-band rasorber phenomenon, and the forward EW exhibits an absorption-transmission-absorption phenomenon with OBs of 644.2 ∼ 671.1 THz, 700.9 ∼ 742.1 THz, and 766.8 ∼ 784.2 THz. RBs with absorption and transmissivity greater than 0.8 are 4.1 %, 5.7 %, and 2.2 %, respectively, and the backward EW one is mainly transmitted. To optimize AAT, a quasi-periodic Octonacci sequence-aligned SCMPC is introduced. The results show that the maximum OB of forward absorption and backward transmission is 428.3 ∼ 670.5 THz and RB is 44.1 %, achieving favorable broadband AAT. In addition, the effects of temperatures, dielectric thicknesses, and stacking numbers on AAT are also investigated in detail. In conclusion, AAT has promising applications in unidirectional optical transmission, photodiodes, optical isolators, etc.

In general, gearbox is prone to occur compound fault frequently because of its harsh working environment, its fault vibration signal often contains polymorphic-oscillatory components and is corrupted by heavy background noise, which brings great difficulty to diagnose fault. Sparse decomposition is often utilized to extract weak fault feature among heavy background noise. In order to solve the problems of traditional sparse decomposition method, such as lacking signal fidelity, causing local optimal solution by using the non-convex objective function, and presenting poor universality, a multi-source sparse optimization objective function with convexity is constructed based on the generalized mini-max concave penalty function. By using forward–backward splitting algorithm combination with Laplace wavelet dictionary, Morlet wavelet dictionary and DFT dictionary, the sparse coefficients corresponding to polymorphic-oscillatory components can be computed efficiently and each oscillatory component can be extracted accurately. Finally, simulation and experimental signal validate that the proposed method can decompose fault signal according to oscillatory property and diagnose gearbox compound fault without the prior knowledge of specific fault numbers.

For the past decade, a number of robotic catheters have been developed for precise and repeatable insertion of endovascular catheters and guidewires. However, using the existing descriptions of a variety of designs and functions it is impossible to systematically evaluate the development of robotic catheters and follow their modifications that lead to improvements in their performance. This systematic literature review focuses on the evolution of robotic catheters in order to define the current results and trends in this field. We have followed the PRISMA guidelines and conducted a comprehensive search of publications reporting design and feasibility tests from January 2011 to December 2023 in the Google Scholar database. The evolution of each model was described in terms of the implemented mechanisms and features. The accuracy, ranges of motion and speed of robotic catheters were compared. The most common number of degrees of freedom of the slave unit of robotic catheters is 2-3. Robotic catheters usually have unlimited translation and rotation ranges, and the speed range varies from 2 to 20 mm/s for translation and from 8 °/s to 20 °/s or from 50 °/s to 70 °/s for rotation. The major part of robotic catheters has the maximum translational trueness between 0.5 and 1.1 mm, and the maximum rotational trueness is between 0.8°and 1.2°, which is enough to execute a precise endovascular procedure. No commercially available robotic catheter has force feedback, however, many of the catheters are developing various elements for it, which suggests that such systems will appear in the future.

This study critically investigates analysis and control of non-isolated boost three-port DC to DC converter (TPC) for standalone PV system. The converter is controlled such that regulates flow of power from PV array to load and batteries as storage devices. According to PV power, there are four operating modes of operation of converter. Simple reduced-order dynamic models of the converter in various modes of operation are obtained using state-space averaging and small-signal techniques. In this work, the controllers of the closed-loop scheme are designed and only two controllers are used to achieve output voltage regulation, and to extract maximum power from PV array under different operating conditions. Closed-loop system simulation is studied to verify the operation of converter with the designed controllers in different modes. Transition between modes is presented with solar radiation variation and change of connected loads. Experimental verification of control systems at different modes of operation is investigated. The experimental results show that the controllers can regulate the power flow between TPC three ports and regulate output voltage under PV irradiance variation and load changing. The controller shows good performance measures such as maximum settling time of 0.06 s, maximum steady-state ripples of ±0.8 %, and 99.3 % power efficiency.

In this study, fluid flow predictions using three different methods were compared: DeepCFD, an artificial intelligence code; computational fluid dynamics (CFD) using Ansys Fluent and OpenFOAM; and two-dimensional, two-component particle image velocimetry (PIV) measurements. The airfoils under investigation were the NACA 0012 with a 10° angle of attack and the NACA 6412 with a 0° angle of attack. To train DeepCFD, 763, 2585, and 6283 OpenFOAM simulations based on primitives were utilized. The investigation was conducted at a free stream velocity of 10 m/s and a Reynolds number of 82000. Results show that once the DeepCFD network is trained, prediction times are negligible, enabling real-time optimization of airfoils. The mean absolute error between CFD and DeepCFD, with 6283 trained primitives, for NACA 0012 predictions resulted in velocity components $U_x$ = 1.08 m/s, $U_y$ = 0.43 m/s, and static pressure p = 4.57 Pa. For NACA 6412, the corresponding mean absolute errors are $U_x$ = 0.81 m/s, $U_y$ = 0.59 m/s, and p = 7.5 Pa. Qualitative agreement was observed between PIV measurements, DeepCFD, and CFD. Results are promising that artificial intelligence has the potential for real-time fluid flow optimization of NACA airfoils in the future. The main goal was not just to train a network specifically for airfoils, but also for variant shapes. Airfoils are used since they are highly sophisticated in fluid dynamics and experimental data was available.

Shrink-fit, wire-winding, and autofrettage processes are commonly utilized to enhance fatigue strength and durability of thick-walled cylinders across various mechanical applications. In this study, a novel practical design optimization methodology has been developed to determine the optimal configuration of a thick-walled cylinder, incorporating different combinations of shrink-fit, wire-winding, and autofrettage techniques. The objective is to identify the optimal layer thickness, shrink-fit interference, conventional autofrettage pressure, and reverse autofrettage pressure, if applicable, to maximize the compressive residual stress and minimize the tensile residual stress, thereby extending fatigue lifetime of the cylinder. First, different configurations of thick-walled cylinders, subjected to various combinations of reinforcement processes, are identified. A dataset of residual hoop stress profiles through the cylinder thickness is subsequently generated for these configurations based on the same manufacturing process. Neural network regression is effectively utilized to construct a single fitting function for the residual hoop stress profiles. A parametric study is performed to determine the optimal training functions, activation functions, and hyperparameters, achieving a remarkable agreement with the dataset, indicated by a coefficient of determination of over 0.97. A combination of Genetic Algorithm and Sequential Quadratic Programming algorithms is utilized to determine the accurate optimal values. Fatigue life analysis is subsequently conducted to estimate the fatigue lifetime of the optimal configuration. Results suggest that the optimal configuration, involving conventional autofrettage of the inner layer followed by shrink-fitting with a virgin layer and wire-winding the entire assembly, achieves a maximum fatigue life of 88 × 10⁶ cycles under cyclic pressure load of 300 MPa.

In response to the escalating global CO2 emissions and the urgent need to reduce dependence on fossil fuels, this study diverges from prior research that predominantly focuses on intentions or attitudes towards renewable energy. It investigates the actual uptake of residential solar photovoltaic (PV) systems in regions rich in solar radiation, where, despite the potential, renewables remain a minor part of the energy mix. Incorporating psychological and functional factors and employing the innovation resistance theory (IRT), the study comprehensively examines solar PV technology’s resistance aspects. Utilizing a robust methodological framework that uses partial least squares-structural equation modeling (PLS-SEM) with fuzzy set qualitative comparative analysis (fsQCA), the research evaluates responses from a comprehensive questionnaire survey of 758 households. The advantages of this method lie in its ability to capture both symmetric and asymmetric relationships, thereby offering a richer and more detailed analysis compared to traditional single-method approaches. PLS-SEM results identify significant barriers: image barriers (β = −0.131, t = 3.418, p < 0.001), traditional barriers (β = −0.084, t = 2.143, p < 0.05), and risk barriers (β = −0.124, t = 4.172, p < 0.001). Positive influences include environmental benefits (β = 0.166, t = 3.108, p < 0.001), environmental concern (β = 0.364, t = 6.341, p < 0.001), and government incentives (β = 0.159, t = 2.767, p < 0.01). Conversely, usage barriers and value barriers appeared non-influential. Conversely, fsQCA revealed that all factors may have a role in the uptake of residential solar PV systems. The novelty of this research is evident in its application of IRT to the context of solar PV adoption and the use of a hybrid analytical method, which together provide new insights into consumer behavior and policy implications. These findings offer actionable recommendations for policymakers and practitioners to promote the adoption of residential solar PV systems.

There are some researches in the literature on the mechanical characteristics of dual-phase (DP) steels used in the automotive industry, but there is no comprehensive research on the corrosion behavior of these steels. In this work, the corrosion behavior of DP steels (DP440, DP590, DP980) exposed to two cycles of accelerated corrosion testing in accordance with Ford CETP 00.00-L-467 was observed. Raman and X-ray diffraction (XRD) techniques were used to classify the corrosion products, and the morphology of the samples was studied using a scanning electron microscope (SEM). Goethite and haematite were the primary chemical compounds determined. In high-mechanical strength DP steels, akaganeite was also identified in corroded specimens. The compounds formed due to corrosion were revealed by SEM images. In this work, according to the results of Raman spectroscopy, which was employed for the first time to reveal corrosion products in high-strength dual-phase steels, it was discovered that corrosion products increased with increasing mechanical strength due to an increasing martensite phase volume percentage. Polarization tests were carried out to support the electrochemical data reported by the Raman analysis. Similarly, an increase in the amount of martensite phase in the microstructure led to a decrease in the material’s corrosion resistance. Polarization experiments were carried out to support the electrochemical data interpreted by Raman analysis. In addition, an increase in the amount of martensite phase in the microstructure led to a decrease in the corrosion resistance of the material. In addition, information regarding the material’s electrochemical performance was obtained through Raman analysis. As shown by Raman, XRD, and polarization tests, the increase in corrosion products formed due to the increase in the amount of martensite led to a decrease in corrosion resistance.

In Turkey, one of the most important earthquake belts in Europe, two major earthquakes (Mw: 7.7 and 7.6) occurred about 8 h apart in Kahramanmaraş province on February 6, 2023. Located on the South Anatolian Fault Zone (EAFZ), Kahramanmaraş province and 10 surrounding provinces were affected by the earthquake, which killed approximately 50,000 people and injured approximately 250,000 people. When the cause of this effect was analyzed, it was determined that the building stock of the region was old, as well as the peak ground acceleration (PGA) values that occurred on the surface and to which the structures were exposed. In addition to structural problems, it has been determined that there are significant ground problems such as ground amplification and ground liquefaction in the geotechnical field. For this reason, it is necessary to accurately determine the spectral acceleration values, which show important parameters in the design of buildings, and to take necessary precautions by identifying problems such as soil bearing capacity, settlement problem, liquefaction, and soil amplification in advance. Turkey Building Earthquake Code (TEC 2019) entered into force in 2019. In this study, surface acceleration records exposed to the structures in the region were analyzed. Earthquake acceleration records were obtained from the stations closest to the epicenters of the earthquakes that occurred in Elbistan and Pazarcık in Kahramanmaraş province, and soil amplification analysis and liquefaction potential risk analysis were performed at 3 different points in Kahramanmaraş province. In addition, 11 earthquake acceleration records were selected from different parts of the world reflecting the earthquake characteristics of the region and the analysis was repeated and the design spectrum was compared with the data obtained from the field. Site-specific soil behavior analyses were performed in the study where the existing conditions of the structures in the region were also examined. The data obtained show that the regulation does not fully reflect the field in cases where the structures are exposed to high acceleration values on the surface due to the soil structure, at the same time, liquefaction problems are high and the structures have not undergone the necessary ground improvement processes.

It is well known that road safety is a major problem in cities, resulting in a large number of accidents with significant injuries and loss of life. Much of this problem occurs when vehicles interact with pedestrians. To try to minimize this problem to a large extent, a combined system using resins and a photoluminescent additive was proposed. To confirm the goodness of this material, a characterisation was carried out covering luminance, vibroacoustic and mechanical properties and a study of its photogrammetry under real conditions of use. A luminance of 68 mcd/m² at 20 min was confirmed, which would allow, by a wide margin, a pedestrian crossing to be observed in a vehicle more than 100 m away. The acoustic vibration test confirmed that the proposed system would provide a very efficient audible warning to pedestrians and would reduce the average vehicle speed by about 37 % overall, while in cases where vehicles have to stop for pedestrians, this reduction would be about 28 %. With the mechanical characterisation, it was possible to determine a vertical displacement of always less than 2 mm in vehicles with a wheel load of 12.5 kN, reaching a compressive and tensile strength of more than 56 MPa. The results obtained confirm a potential reduction in mortality of close to 110 %, and injuries by approximately 55 %, as a consequence of the reduction in vehicle speed. In addition, improved night-time visibility of pedestrian crossings would reduce deaths by 35 % and injuries by 26 %, while in the most favourable situations, these values would be 14 % and 10 % for deaths and injuries respectively. All this confirms the great advantage of the system for improving road safety in urban environments.