Hasil untuk "Mechanical engineering and machinery"

Xiaopeng Yuan, Haoyu Wang, Lei Zhang

This paper presents a semi-circular, non-contact current sensor designed to simplify the layout of automotive wiring harnesses and enhance measurement convenience and reliability. The sensor integrates a hybrid sensing array consisting of Hall-effect and tunnel magnetoresistance (TMR) elements. To address common challenges in automotive power systems and vehicle wiring—such as conductor eccentricity and magnetic interference from adjacent cables—two key techniques are proposed. First, an eccentricity error compensation algorithm is developed, achieving a measurement accuracy of 97.07% under specific misalignment conditions. Second, an equivalent modeling method based on eccentricity principles is introduced to characterize interference fields in complex wiring environments, maintaining 94.31% accuracy in the presence of external disturbances. When the conductor is centered within the array, the average measurement accuracy reaches 99.05%. Experimental results demonstrate that the proposed sensor can reliably measure large currents from 0 to 210 A, making it highly suitable for applications in electric vehicles, high-voltage harness monitoring, power electronics, and intelligent transportation systems.

Lis Corral-Gómez, Octavio Armas, Francisco Moya-Fernández et al.

The evolution of the main macroscopic parameters that characterize spray formation for three different fuels is studied by means of the Schlieren visualization technique. The annalized fuels comprise a fossil diesel fuel, used as reference, and two neat low carbon liquid 100% paraffinic fuels: a gas-to-liquid (GtL) and a hydrotreated vegetable oil (HVO). Additionally, the paper exposes the behavior of fuels autoignition for different injection pressures and start of energizing (SoE), for prescribed thermodynamic variables inside the engine cylinder. The experimental results obtained at the beginning of the injection process are compared with results from known models of penetration and cone angle of the fuel spray under non-evaporative conditions. These conditions are chosen to match those of the diesel engines used in surveillance light aircraft such as small helicopters. This work presents two important novelties: (i) the application of an automatic image analysis procedure (previously published) to the fuel injection process and (ii) the comparison of different fuels, regarding their effect on the injection process and the start of combustion. This is done under complete replacement of fossil fuel by two 100% paraffinic fuels. The most important results are the following: i) Compared to GtL and Diesel fuels, the HVO fuel has shorter ignition delay. This result could be attributed to its higher cetane number. ii) However, in most of the tested cases, in addition to a slightly longer spray penetration of the HVO fuel, its cone angle is also slightly wider than that of the other two fuels. This result would be collaborating in the development of a wider spray surface during the evolution of the spray lift off and beyond. This leads to a better air entrainment, and, in consequence, to produce an additional shortening of the ignition delay compared to the other two fuels. These findings would facilitate the fine tuning of modern engine technology for a progressive introduction of mentioned low carbon fuels in light aircraft such as unmanned helicopters for surveillance.

S. Tamaro, F. Campagnolo, C. L. Bottasso

<p>We present an active power control (APC) algorithm for wind farms that operates wind turbines to maximize their power availability in order to robustly track a reference power signal in the presence of turbulent wind lulls. The operational setpoints of the wind turbines are optimized using an engineering flow model by combining induction control with wake steering. The latter has the goal of deflecting low-momentum wakes and increasing power margins. The algorithm also features a proportional–integral closed loop inspired by the literature to correct potential errors deriving from the offline computation of the setpoints.</p> <p>First, we demonstrate the new approach in steady-state conditions, showing how the availability of power is increased by mitigating wake interactions. We observe that our proposed method is particularly effective in conditions of strong wake impingement, occurring in scenarios of high power demand. Next, considering two wind farm layouts, we compare the performance of the algorithm to three state-of-the-art reference APC formulations in unsteady scenarios using large-eddy simulations coupled with the actuator line method (LES-ALM). We show that the occurrence and treatment of local temporary instances of power unavailability (<i>saturations</i>) dramatically affect power tracking accuracy. The proposed method yields superior power tracking due to the increased power margins that limit the occurrence of saturation events. Additionally, we show that this performance is achieved with reduced structural fatigue.</p>

Zhenggang Chen, Wei Wu, Shaocheng Tong

This paper investigates the problem of fuzzy adaptive finite-time inverse optimal control for active suspension systems (ASSs). The fuzzy logic systems (FLSs) are utilized to learn the unknown non-linear dynamics and an auxiliary system is established. Based on the finite-time stability theory and inverse optimal theory, a fuzzy adaptive inverse finite-time inverse optimal control method is proposed. It is proven that the formulated control approach guarantees the stability of the controlled systems, while ensuring that errors converge to a small neighborhood of zero within finite time. Moreover, the optimized control performance can be achieved. Eventually, the simulation results demonstrate the effectiveness of the proposed fuzzy adaptive finite-time inverse optimal control scheme.

Zhaogang Jing, Yusheng Jian, Feng Guo et al.

The effects of tuned surface wettability on oil film formation in a hydrodynamically lubricated contact with a limited lubricant supply (LLS) were explored in this study. Using a slider-on-disc lubricating film test rig, the oil film thickness was measured for three surface wettability configurations: the original disc surface and original slider side surface (OD & OS), the anti-fingerprint (AF)-coated disc surface and original slider side surface (AFD & OS), and the AF-coated disc surface and the AF-coated slider side surface (AFD & AFS). The results indicate that the AFD & AFS combination maintains the largest oil film thickness. This enhanced performance is due to the oil’s nonwetting behavior on the AFD & AFS surfaces, particularly the discontinuous oil droplet/strip by dewetting, which promotes more lubricant supply at the slider inlet. Moreover, the oil accumulates at the inlet in the form of a convex reservoir so that positive Laplace pressure is generated, which effectively bears part of the load, and the film thickness increases.

Wei Shixiong, Yang Jianjun, Wei Bingyang et al.

The bearing performance and wear condition of the turning arm bearing of cycloidal reducers are closely related to the rotary accuracy and life of reducers. Aiming at the actual wear condition of a 150BX type cycloidal reducer bearing hole, first of all, the bearing model of the turning arm bearing was established, and the change rules of the maximum load and its direction were established. Then the motion models of the cycloidal gear and crankshaft containing manufacturing errors were established, the interference of the manufacturing errors on the movement of the turning arm bearing was analyzed, and the maximum interference position on the turning arm bearing and the error selection method were obtained. The findings of this study provide a basis for the wear calculation of the turning arm bearing of the cycloidal reducer and the error selection of key components.

J. P. Murcia Leon, H. Habbou, M. Friis-Møller et al.

<p>Hybrid renewable power plants consisting of collocated wind, solar photovoltaic (PV), and lithium-ion battery storage connected behind a single grid connection can provide additional value to the owners and society in comparison to individual technology plants, such as those that are only wind or only PV. The hybrid power plants considered in this article are connected to the grid and share electrical infrastructure costs across different generation and storing technologies. In this article, we propose a methodology for sizing hybrid power plants as a nested-optimization problem: with an outer sizing optimization and an internal operation optimization. The outer sizing optimization maximizes the net present values over capital expenditures and compares it with standard designs that minimize the levelized cost of energy. The sizing problem formulation includes turbine selection (in terms of rated power, specific power, and hub height), a wind plant wake loss surrogate, simplified wind and PV degradation models, battery degradation, and operation optimization of an internal energy management system. The problem of outer sizing optimization is solved using a new parallel “efficient global optimization” algorithm. This new algorithm is a surrogate-based optimization method that ensures a minimal number of model evaluations but ensures a global scope in the optimization. The methodology presented in this article is available in an open-source tool called HyDesign. The hybrid sizing algorithm is applied for a peak power plant use case at different locations in India where renewable energy auctions impose a monetary penalty when energy is not supplied at peak hours. We compare the hybrid power plant sizing results when using two different objective functions: the levelized cost of energy (<span class="inline-formula">LCoE</span>) or the relative net present value with respect to the total capital expenditure costs (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><mrow class="chem"><mi mathvariant="normal">NPV</mi></mrow><mo>/</mo><mrow class="chem"><msub><mi mathvariant="normal">C</mi><mi mathvariant="normal">H</mi></msub></mrow></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="44pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="f147e6b10aef704514edc5586dee8b93"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="wes-9-759-2024-ie00001.svg" width="44pt" height="14pt" src="wes-9-759-2024-ie00001.png"/></svg:svg></span></span>). Battery storage is installed only on <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mrow class="chem"><mi mathvariant="normal">NPV</mi></mrow><mo>/</mo><mrow class="chem"><msub><mi mathvariant="normal">C</mi><mi mathvariant="normal">H</mi></msub></mrow></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="44pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="0c97fe39a91af71c5f466cc2e94b80af"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="wes-9-759-2024-ie00002.svg" width="44pt" height="14pt" src="wes-9-759-2024-ie00002.png"/></svg:svg></span></span>-based designs, while the hybrid design, including wind, solar, and battery, only occurs on the site with good wind resources. Wind turbine selection on this site prioritizes cheaper turbines with a lower hub height and lower rated power. The number of batteries replaced changes at the different sites, ranging between two or three units over the lifetime. A significant oversizing of the generation in comparison to the grid connection occurs on all <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><mrow class="chem"><mi mathvariant="normal">NPV</mi></mrow><mo>/</mo><mrow class="chem"><msub><mi mathvariant="normal">C</mi><mi mathvariant="normal">H</mi></msub></mrow></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="44pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="a79fa39f5ba41b881215ca0cbb33976d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="wes-9-759-2024-ie00003.svg" width="44pt" height="14pt" src="wes-9-759-2024-ie00003.png"/></svg:svg></span></span>-based designs. As expected <span class="inline-formula">LCoE</span>-based designs are a single technology with no batteries.</p>

Mohammed A. Hassan, Mahmoud M. Adel, Ahmed Farhan et al.

This paper proposes a novel finite speed-set model reference adaptive system (FSS-MRAS) based on the current predictive control (CPC) of a permanent magnet synchronous generator (PMSG) in wind energy turbine systems (WETSs). The mathematical models of wind energy systems (WESs) coupled with a permanent magnet synchronous generator (PMSG) are presented in addition to the implementation of the CPC of PMSGs. The proposed FSS-MRAS is based on eliminating the tuning burden of the conventional MRAS by using a limited set of speeds of the PMSG rotor that are employed to predict the rotor speed of the generator. Consequently, the optimal speed of the rotor is the one resulting from the optimization of a proposed new cost function. Accordingly, the conventional MRAS controller is eliminated and the main disadvantage represented in the tuning burden of the constant-gain proportional-integral (PI) controller has been overcome. The proposed FSS-MRAS observer is validated using MATLAB/Simulink (R2023b) at different operating conditions. The results of the proposed FSS-MRAS have been compared with those of the conventional MRAS, which proved the high robustness and reliability of the proposed observer.

Yongli Zhu, Chanan Singh

This letter develops a fast analytical method for uncertainty quantification of electromechanical oscillation frequency due to varying generator dampings. By employing the techniques of matrix determinant reduction, two types of uncertainty analysis are investigated to quantify the impact of the generator damping on electromechanical oscillation frequency, i.e., interval analysis and probabilistic analysis. The proposed analytical frequency estimation formula is verified against conventional methods on two transmission system models. Then, Monte Carlo experiments and interval analysis are respectively conducted to verify the established lower/upper bound formulae and probability distribution formulae. Results demonstrate the accuracy and speed of the proposed method.

Tri Hieu Le, Minh Tuan Pham, H Hadiyanto et al.

Passive solar still is the simplest design for distilling seawater by harnessing solar energy. Although it is undeniable that solar still is a promising device to provide an additional freshwater source for global increasing water demand, low thermal efficiency along with daily distillate yield are its major disadvantages. A conventional solar still can produced 2 to 5 L/m2day. Various studies have been carried out to improve passive solar stills in terms of daily productivity, thermal efficiency, and economic effectiveness. Most of the researches that relate to the daily output improvement of passive solar still concentrates on enhancing evaporation or/and condensation processes. While the condensation process is influenced by wind velocity and characteristics of the condensed surface, the evaporation process is mainly affected by the temperature of basin water. Different parameters affect the brackish water temperature such as solar radiation, design parameters (for example water depth, insulators, basin liner absorptivity, reflectors, sun tracking system, etc). The inclined angle of the top cover is suggested to equal the latitude of the experimental place. Moreover, the decrease of water depth was obtained as a good operational parameter, however, the shallow water depth is required additional feed water for ensuring no dry spot existence. Reflectors and sun-tracking systems help solar still absorb as much solar intensity as possible. The internal reflector can enhance daily yield and efficiency of stepped solar still up to 75% and 56% respectively, whereas, passive solar still with the support of a sun-tracking system improved daily yield up to 22%. Despite large efforts to investigate the impact of the different parameters on passive solar distillation, the effect of the basin liner (including appropriate shapes and type of material), needs to be analyzed for improvement in practical utilization. The present work has reviewed the investigation of the solar still performance with various types of basin liner. The review of solar stills has been conducted critically with rectangular basin, fins basin, corrugated basin, wick type, steps shape, and cylindrical shape basin with variety of top cover shapes. The findings from this work conclude that the basin liner with a cylindrical shape had better performance in comparison with other metal types and provides higher freshwater output. Stepped type, inclined, fin absorber, and corrugated shapes had the efficient performance.  Further exploration revealed that copper is the best-used material for the productivity of passive solar still.

Dazhi Wang, Kuipeng Zhao, Yuheng Yuan et al.

This paper proposes a novel way of preparing a PZT thick film micro vibrator using the electrohydrodynamic jet (E-Jet) printing technique. Initially, a micro piezoelectric vibrator was simulated and designed for obtaining optimized structure, which has a total thickness of less than 600 µm. Subsequently, the PZT thick film element was directly printed on the elastic body using the E-Jet printing. This method avoids the glue fabrication process involved in the bulk piezoelectric fabrication, thus avoiding the limits of voltage drops, isolating and absorbing amplitude usually occurred in the vibrator having glue interface. It was observed that B02 and B03 modes were generated at frequencies of 29.74 and 79.14 kHz, respectively, and the amplitudes of B02 and B03 modes were 406 and 176 nm, respectively. The error between the simulation and test result in the B03 modal is only 0.35%, which indicates the accuracy of the simulation analysis and the fabrication process. The PZT thick film traveling-wave micro vibrator successfully realized bidirectional rotation of a rotor, with a maximum speed of 681 rpm, which also shows a linear relationship between excitation voltage and rotary speed. This paper provides an effective method for preparing a micro piezoelectric vibrator for MEMS ultrasonic devices, which simplifies the manufacturing process and enhances the performance of the piezoelectric vibrator.

K. Dhoska

F. O. Hamdoon, H. Al-Bugharbee, A. S. Hameed

During startup process of rotating machinery and due to the rotor’s inherent unbalance, transient vibration is introduced as the machinery passes through critical speeds. In the present paper, time domain simulation is performed using ANSYS software to investigate the transient unbalance response of rotor – bearing system. The transient vibration response of the rotor system passing through the critical speeds is analysed under different startup speed profiles. Startup speed profile is represented by exponential formula with single parameter (δ) that indicates whether the startup speed is rapid or slow. The results show that for slow machine startup; the system will remain at the critical speeds for a long period allowing the vibration response to be increased. On the other hand, rapid machine startup passing through the critical speeds will reduce the vibration response. In addition, the numerical simulation results show that applying initial slow startup speed profile followed by instantaneous switch to rapid startup speed profile can reduce the vibration response significantly and more than for applying only rapid startup speed profile.

D. Le, A. Nguyen, T. Tran et al.

The metal spraying was discovered very early. The important uses of this method are the processing and restoration of damaged machinery-parts that are corrosion or incorrect. Material which only needs a small amount compared to the whole of new parts that must be reproduced, used in the restoration. In some cases, restoration of the machinery-parts will have quality and the long-life higher than the new parts. This report presents a study that is about the design of combust-spaying and the heat treatment process.

F. Barron

Food engineering is considered a specialized engineering field, typically aligning within agricultural and chemical engineering. A food engineer may obtain further skills mainly through a university degree or industrial experience. When compared with other degrees such as chemical and mechanical engineering, a fundamental difference is indicated by specialized areas in food processing, food microbiology, and other related biological areas such as biochemistry. Typical industrial food engineering activities include: designing and optimizing food processes, development of food products, quality and safety assurance, selection and installation of food processing equipment.

Wang Baojian, Liu Wanli, Yang Ke

ABAQUS, as a large-scale non-linear finite element analysis software, is widely used in mechanical engineering structure calculation. Among them, the plastic damage model of concrete is recognized as the most effective model to simulate the inelastic behavior of concrete under repeated loads. It is widely used in the time history calculation and analysis of high-rise buildings, In mechanical engineering, this model is also needed to study the failure mechanism of mechanical cutters on concrete. But in the application of ABAQUS concrete plastic damage model, users need to input the tensile and compressive damage factor-inelastic strain parameter table. ABAQUS does not give the corresponding parameter table of concrete with different strength. Based on the research results of the former and the uniaxial constitutive relation of concrete recommended in the Code for the Design of Concrete Structures, this paper further studies the fitting equation of the tensile and compressive damage factorinelastic strain curve of various strength concrete by means of numerical analysis method, which makes up for the vacancy of ABAQUS and makes the plastic damage model of concrete more suitable and more accurately. The damage factor equation under this study can provide an effective reference for concrete research and greatly facilitate the concrete analysis of later scholars.

P. Ziółkowski, J. Badur, H. Pawlak-Kruczek et al.

Prasad Bhelsekar, C. Kale, Sushant Bile et al.

Yoichiro Yamazaki, Seiji Saiki, N. Koga et al.

Zaure Bayanovna Rakisheva, Nadia Kudryavtseva, Aigerim Kuandykovna Sakhayeva

For the coastal countries, the Caspian Sea is an essential economic object, including the implementation of transport routes, fishing, the availability of potential mineral resources of the seabed and deeper layers. Also, the ecological state of this region is of great importance. Therefore, the study of the wave climate of the sea is vital for all riparian countries. Satellite altimetry has become an increasingly important technology for monitoring of continental surface waters. In this article, we explore a possibility to obtain reliable information on the wave climate in the Caspian Sea using satellite altimetry. We used measurements of significant wave heights from a Jason-1 mission over ten-year period. The data were cleaned and checked for the possible errors. The analysis of average significant wave heights in the Caspian Sea showed overall a consistent picture. The highest wave heights are observed in the Middle part of the basin. The waves have lesser intensity in the Southern basin and the Northern part. The analysis of seasonal variability showed that the most energetic waves appear in the winter season.