This article presents a direct torque control (DTC) scheme with an integrated switching strategy to reduce commutation torque ripple in a dual inverter-fed three-phase BLDC motor with open-end stator windings. The proposed scheme covers both low- and high-speed operation, utilizing voltage space vector structures in two-phase and three-phase conduction modes. Analysis shows that utilizing three-phase conducting voltage vectors during the commutation interval significantly reduces torque ripple compared to the DTC scheme using only two-phase conducting voltage space vectors. The two-phase conducting voltage vectors however maximize electromagnetic torque during the non-commutation period. The proposed scheme results in unipolar switching that minimizes dv/dt leading to further reduction in torque ripple. Experimental validation on a laboratory prototype using a TMS320F28377S controller confirms the effectiveness of the proposed method.
Seyit Alperen Celtek, Seda Kul, A. Ozgur Polat
et al.
The increasing adoption of electric vehicles (EVs) has led to the widespread implementation of battery swapping stations. However, ensuring fairness in battery pricing remains a significant challenge since variations in battery health and performance among swapped batteries can result in user dissatisfaction and operational inefficiencies. This paper introduces a novel approach to enhance fairness in battery swapping by integrating a machine learning-based real-time prediction model with a pricing strategy based on remaining useful life (RUL) estimation to address this issue. The proposed solution comprises a real-time RUL estimation system and a dynamic pricing mechanism that ensures fair pricing based on battery health and performance. This integrated approach aims to improve user satisfaction and the operational efficiency of swapping stations. The paper evaluates various machine learning algorithms for real-time RUL estimation regarding accuracy, computation time, and memory usage. The results suggest that XGBoost provides the most suitable balance between accuracy and efficiency, making it an effective solution for real-world applications. Comparative analysis shows that the XGBoost model outperforms the second-best method (Random Forest) with a lower error (3.50 vs 3.79) while maintaining competitive computational efficiency (9.75 vs 8.52 seconds) and memory usage (2.12 vs 2.32 MB) when solving a typical numerical case study problem. The proposed approach has the potential to accelerate the adoption of electric vehicles and contribute to sustainability goals by promoting efficient battery utilization and fair pricing mechanisms.
Ehsan Kasehchi, Mohammad Ali Arjomand, Mohammad Hadi Alizadeh Elizei
The experimental study of geopolymeric stabilized samples based on ceramic waste powder (CWP) and sodium hydroxide solution acting as an alkali activator was investigated in the present research to evaluate the possibility of geopolymeric stabilization of silty sand soil as a sustainable method for improving the mechanical properties of inshore sand soils. X-ray fluorescence spectroscopy (XRF) was employed to analyze and determine the chemical components of the CWP and natural soil. The effect of four factors on the unconfined compression strength (UCS) and failure strain (Ɛf) of silty sand soil, including CWP content (0–24%), NaOH solution concentration (0–15 M), the curing time (7, 28, and 91 days), and the initial curing temperature (25°C and 70°C), were investigated. The results demonstrated a substantial increase in both UCS and Ɛf for geopolymeric stabilized samples in comparison to natural soil and the soil that was stabilized with 5% ordinary Portland cement (OPC). The UCS and Ɛf values of the 28-day-cured optimal sample (CWP = 15% and NaOH solution concentration = 6 M) in comparison with natural soil increased from 0.080 to 2.22 MPa and from 2.31% to 5.45%, respectively. Moreover, the UCS value in this sample was 1.75, 1.81, and 1.29 times higher than the stabilized soil with 5% OPC for each curing time. Without an alkali activator, CWP addition to the soil had no effect on UCS at all curing times. However, when a 2 M NaOH solution was added to the soil without CWP, the UCS of this sample rose to 0.36 MPa after 7 days of curing. The UCS of geopolymeric stabilized samples experienced growth from 1.27 to 2.04 times by shifting the initial curing temperature from 25°C to 70°C. Through the use of energy-dispersive X-ray (EDX) spectra and scanning electron microscope (SEM) photomicrograph, the microstructure of stabilized samples was inspected. SEM photomicrographs corroborated the UCS test findings, and EDX analysis confirmed the high quality of the aluminosilicate gels' growth and production. To sum up, soil stabilization using CWP geopolymer is a cost-effective, environmentally friendly method that reduces the consumption of natural resources and energy.
Materials of engineering and construction. Mechanics of materials
Dmytro V. Pavlenko, Daria V. Tkach, Yevgen V. Vyshnepolskyi
et al.
The technology of manufacturing aluminum alloy workpieces using additive friction stir deposition (AFS-D) has been thoroughly investigated. The ambiguous influence of deformation processing modes on the material density was found. Examination of the microstructure in the central zone of the specimens reveals the absence of microdefects typically associated with workpieces obtained through casting or powder metallurgy methods. It has been observed that the distribution of microhardness is significantly affected by the direction of specimen construction, with approximately a 20% difference in values between the periphery and the central part of the specimen. Specimens produced using the AFS-D method exhibit a homogeneous microstructure characteristic of deformable aluminum alloys. Notably, a uniform distribution of intermetallides on the specimen surface has been identified. This outcome is likely a result of the alloy undergoing recrystallization during the severe plastic deformation process, leading to the formation of an ultradisperse structure. It is important to emphasize that the selection of technological parameters for AFS-D should consider not only the magnitude of pressure and deformation but also the deformation speed.
Materials of engineering and construction. Mechanics of materials
Steel furnace slag containing heavy metal components is covered by asphalt cement when it is used to replace natural aggregates in road paving. When such a pavement deteriorates as a result of wear by people and vehicles as well as washing by rain, the aggregates are worn away and the heavy metal components within can overflow on the road’s surface, forming rust spots. This phenomenon has been observed on many roads, leading the general public to question the validity of using steel furnace slag and whether this is in violation of a contract with the contractor. However, it is known from literature that such rust spots on a road surface may also be caused by natural minerals such as pyrite that are contained in natural aggregates. Unlike cement concrete, the slag cannot be separated from the mixture after hardening; however, the asphalt cement can be separated from the aggregates by using a solvent. In this study, separated aggregates are tested for pH value, magnetic attraction, and elemental composition in order to assess the usability of slag. Based on the findings and the characteristics of steel furnace slag, this paper proposes a method for detection of steel furnace slag in asphalt concrete, which is divided into two stages. In the first stage, core samples of asphalt concrete are obtained from the road site. The asphalt cement is separated from the aggregates according to AASHTO T164 and then the separated aggregates are analyzed in pH value and magnetic attraction tests. When one or both of the tests indicate steel furnace slag characteristics, that is, alkalinity or magnetism, then it is possible that the asphalt concrete sample contains steel furnace slag, and should be tested in the second stage for further confirmation. In the second stage, the separated aggregates are grinded to less than 0.075 mm (No. 200) and their elemental composition is analyzed. Based on the composition of steel furnace slag, when the analysis results indicate ≥30 % CaO and ≥10 % Fe2O3, it can be regarded that steel furnace slag has been used in the asphalt concrete.
Materials of engineering and construction. Mechanics of materials
Gennady V. Arkadov, Vladimir I. Pavelko, Vladimir P. Povarov
et al.
The insufficiently studied issues of acoustic standing waves (ASW) in the main circulation circuits of the VVER reactor plants are considered. For a long time no proper attention has been given to this phenomenon both by the researchers and NPP experts. In general, generation of ASWs requires the acoustic inhomogeneities of the medium in the planes perpendicular to the direction of propagation of the longitudinal wave, in which a jump in acoustic resistance occurs, this is shown by the authors based on an example of the wave equation solution (D’Alembert equation) for a certain function of two variables. The ASW classification has been developed based on the obtained experimental material, 6 ASW types have been described, and their key parameters have been specified. The amplitude distributions have been plotted for all major ASW types proceeding from the phase relations of signals from the pressure pulsation detectors and accelerometers installed on the MCC pipelines. The nature of these distributions is general and they are valid for all VVER types. For the first time the globality of all lowest ASW types is identified. Four attribute properties of the ASWs have been formulated. The first attribute is the regular ASW temperature dependences, which is the source of the diagnostic information in the process of heating/cooling of the VVER unit. The linear experimental dependences of the ASW frequencies on coolant temperature have been obtained. The frequencies, at which the MCC resonant excitation due to coincidence of the ASW frequencies with the RCP rotational frequency harmonics, have been found experimentally. The ASW energy, which origin has resulted from the RCP operation, is estimated. The RCP operation can be presented as continuous generation of pressure pulsations, which fall onto the acoustic path inhomogeneities in the form of a traveling wave and generate a standing wave after reflection from them.
Toko Tokunaga, Koji Hagihara, Michiaki Yamasaki
et al.
The variation in the mechanical properties with the volume fraction of the long-period stacking ordered (LPSO) phase in directionally solidified (DS) Mg/LPSO two-phase alloys was examined. Unexpectedly, the yield stress of the DS alloys increases non-monotonically with an increase in the volume fraction of the LPSO phase. The LPSO phase is considered an effective strengthening phase in Mg alloys, when the stress is applied parallel to the growth direction. Nevertheless, the highest strength was obtained in alloys with 61–86 vol.% of the LPSO phase, which was considerably higher than that in the LPSO single-phase alloy. It was clarified that this complicated variation in the yield stress was generated from the change in the formation stress of kink bands, which varied with the thickness of the LPSO-phase grains. Furthermore, the coexistence of Mg in the LPSO phase alloy induced the homogeneous formation of kink bands in the alloys, leading to the enhancement of the ‘kink-band strengthening’. The results demonstrated that microstructural control is significantly important in Mg/LPSO two-phase alloys, in which both phases exhibit strong plastic anisotropy, to realize the maximum mechanical properties.
Materials of engineering and construction. Mechanics of materials, Biotechnology
This paper proposes a new nature-inspired metaheuristic algorithm called Clouded Leopard Optimization (CLO), which mimics the natural behavior of clouded leopards in the wild. The fundamental inspiration of CLO is derived from two ways of natural behaviors of the clouded leopard, including hunting strategy and daily resting on trees. CLO is mathematically modeled in two phases of exploration and exploitation, based on the simulation of these two natural behaviors. CLO performance is evaluated in solving sixty-eight benchmark functions, including unimodal, multimodal, CEC 2015, and CEC 2017 types. The performance of CLO in solving optimization problems is compared with the performance of ten famous metaheuristic algorithms. The simulation results show that the proposed CLO approach with high ability in exploration, exploitation, and balancing between them has a high capability in optimization applications. Simulation results show that CLO performs better in most test functions than competitor algorithms. In addition, the implementation of CLO on four engineering design issues demonstrates the capability of the proposed approach in real-world applications.
State-of-charge (SOC) estimation of lithium-ion batteries in portable devices without sensing the current is considered in this study. Unlike the traditional approach of separate estimation of the SOC and current, we firstly reformulate the problem as state estimation for the nonlinear system with an unknown input which refers to the current in this study, then a novel variational Bayes-based unscented Kalman filter (VB-UKF) is proposed to simultaneously estimate the SOC and the current input for the nonlinear lithium-ion battery system. Verifications of the SOC estimation performance are made by the experiments under the pulsed-discharge profile and urban dynamometer driving schedule profile. Experimental results show that the proposed VB-UKF algorithm is superior to the unscented recursive three-step filter (URTSF) in terms of convergence rate and estimation accuracy of the SOC and current. And the SOC root mean square errors of VB-UKF are bounded within ±3% after convergence which indicates the feasibility and effectiveness of the proposed method.
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.
Production of electric energy or power. Powerplants. Central stations, Renewable energy sources
With the superiorities of providing network services for all scenarios of three-dimensional space, air, ground, and ocean, and satisfying the future network differential requirements on all services, the satellite-terrestrial integrated network (STIN) has become a hot spot in the development of 6G.Firstly, the current research development of the low-orbit satellite constellation and STIN were reviewed, and the challenges faced by the integrated satellite-terrestrial networking were discussed.Then, the software defined intelligent system architecture of the integrated satellite-terrestrial wireless network based on distributed SDN controllers was proposed to address the characteristics of STIN such as the complex architecture, high dynamic of network topology, the heterogeneity of network devices and protocols, which facilitated efficient satellite-terrestrial collaborative network management and control.In the end, the key techniques of the satellite-terrestrial flexible and reconfigurable collaborative networking were outlined, and the future development were presented.
T. M. C. C. Aalseth, S. Abdelhakim, F. Acerbi
et al.
Large liquid argon detectors offer one of the best avenues for the detection of galactic weakly interacting massive particles (WIMPs) via their scattering on atomic nuclei. The liquid argon target allows exquisite discrimination between nuclear and electron recoil signals via pulse-shape discrimination of the scintillation signals. Atmospheric argon (AAr), however, has a naturally occurring radioactive isotope, 39Ar, a β emitter of cosmogenic origin. For large detectors, the atmospheric 39Ar activity poses pile-up concerns. The use of argon extracted from underground wells, deprived of 39Ar, is key to the physics potential of these experiments. The DarkSide-20k dark matter search experiment will operate a dual-phase time projection chamber with 50 tonnes of radio-pure underground argon (UAr), that was shown to be depleted of 39Ar with respect to AAr by a factor larger than 1400. Assessing the 39Ar content of the UAr during extraction is crucial for the success of DarkSide-20k, as well as for future experiments of the Global Argon Dark Matter Collaboration (GADMC). This will be carried out by the DArT in ArDM experiment, a small chamber made with extremely radio-pure materials that will be placed at the centre of the ArDM detector, in the Canfranc Underground Laboratory (LSC) in Spain. The ArDM LAr volume acts as an active veto for background radioactivity, mostly γ-rays from the ArDM detector materials and the surrounding rock. This article describes the DArT in ArDM project, including the chamber design and construction, and reviews the background required to achieve the expected performance of the detector.
Abstract Development of solid state photon detectors is a mature field of engineering and technology based on well-established grounds of solid state physics, and, in the same time, a frontier area of research and innovations faced with dramatic challenges. The ultimate challenge for the modern developments is a detection of optical signals at a quantum level – resolving arrival time and spatial location of individual photons – to realize a formula “every photon counts”. To succeed, the developments are focused on improvements in three directions: threshold sensitivity and photon number resolution, fast timing and time resolution, and fine granularity imaging with fast readout. There are many inherent trade-offs to be resolved in each direction. Development of Silicon Photomultiplier (SiPM) is considered as one of the most promising innovations toward “near ideal” photon detector. SiPMs of various designs have been developed in the 1990s–2000s in Russia, and their unique performance in the photon number and time resolution has been demonstrated and recognized in the mid-2000s. Now SiPMs are widely implemented in nuclear medicine, high energy physics, astrophysics, and Cherenkov light detection. However, developers of Geiger Mode APD or SPAD arrays based on active quenching also found new approaches and opportunities for considerable improvements using modern CMOS technology, namely: reduction of a dead space occupied by electronics, multiplexing readout architecture, backside illumination, and 3D integration of photosensor and electronic layers (3D digital SiPM). Detection of Cherenkov light is one of the most challenging applications for photodetectors. Superior photon number resolution starting from single photons, picosecond-scale time resolution, and large-area imaging are typical requirements, and all these highly demanded capabilities are contradictory. This report presents overview and analysis of the state-of-art in the modern solid state photon detectors as well as their potential and perspectives to meet the quantum imaging challenge.
The random Fourier feature as an efficient kernel approximation method can effectively suppress the network growth of the traditional kernel-based adaptive filtering algorithm. Polarized random Fourier feature kernel least-mean-square(PRFFKLMS) remarkably improved the accuracy performance of random Fourier feature-based kernel least-mean-square algorithm and become the most representative random Fourier feature-based least-mean-square algorithm. In this paper, we studied the method that can improve the convergence speed of random Fourier feature-based least-mean-square algorithm. Based on the variable forgetting factor and variable step size strategy, three algorithm are proposed. The computational complexity of proposed algorithms are also given. The simulation results show that compared with PRFFKLMS algorithm, the convergence speed of the proposed algorithm is significantly improved.
The great chemical affinity of molecular iodine towards several macromolecules and innumerable polymers allows the formation of macromolecule/polymer-iodine complexes, usually commensurate with the desired uses and applications. In many instances, the formation of such complexes occurs through a charge-transfer mechanism. The strength of the ensued complex is more accentuated by the presence of heteroatoms (nitrogen, oxygen, sulfur) and the π-conjugation induced moieties within the chemical structure of the polymer. A wide range of polymers with high specific surface areas and large total pore volumes are excellent candidates for iodine adsorption, suggesting their use in the removal of radioactive iodine in nuclear power plants. The recent results of iodine uptake by polysaccharides such as starch, chitin, chitosan, alginate, and cellulose are but novelties. Complexing vinyl polymers such as poly(N-vinyl-2-pyrrolidone), poly(vinyl pyridine), poly(vinyl alcohol), poly(vinyl chloride), poly(acrylonitrile), and polyacrylics, with molecular iodine revealed special chemistry, giving rise to polyiodide ions (In -) as the actual complexing agents. Carbon allotropes (graphene, graphene oxide, carbon nanotubes, amorphous carbons) and polyhydrocarbons are prone to interact with molecular iodine. The treatment of a broad set of polymers and macromolecules with molecular iodine is but a doping process that ends up with useful materials of enhanced properties such conductivity (electrical, ionic, thermal); in some cases, the obtained materials were of engineering applications. Complexation and doping materials with iodine are also aimed at ensuring the antimicrobial activity, particularly, for those intended for medical uses. In several cases, the impact of the iodine doping of polymer is the alteration of its morphology, as is the case of the disruption of the graphitic morphology of the graphene or graphene oxide.
The goal of nuclear fusion is one of the most important challenges in contemporary research and technological development. Its achievability will completely change the energy scenario and reduce the dependence on fossil fuels in the production of electricity. ITER project is focusing the efforts of many countries and researchers in the demonstration of nuclear fusion achievability. Beside the challenges related to the physic of plasma any other challenges in the engineering filed must be faced to realize such an ambitious goal. Among them, the electrical power supply of the ITER superconductive coils will be very demanding. Due to the particularity of the load, the total reactive power requested will exceed the limits imposed by the Transmission System Operator imposing to implement dedicated reactive power compensation strategies. This paper focuses on the two reactive power compensation systems that will be installed at ITER site, focusing on their interaction in terms of voltage stability during fast variations, such as load rejection. As will be shown later in the article, two main strategies for the reactive power sharing are considered. Results concerning both strategies will be analyzed and discussed in terms of system stability and the respect of design voltage limits.
In this paper, we illustrate an application of the Laplace transformation for finding the quantum mechanical Reflection and Transmission coefficients for a particle through a one-dimensional vertical step potential. Quantum mechanics is one of the branches of physics in which the physical problems are solved by algebraic and analytic methods. By applying the Laplace transformation, we can find the quantum mechanical Reflection and Transmission coefficients for a particle through a one-dimensional vertical step potential. Generally, the Laplace transformation has been applied in different areas of science and engineering and makes it easier to solve the problems inengineering applications. It is a mathematical tool which has been put to use for solving the differential equations without finding their general solutions. It has applications in nearly all science and engineering disciplines like analysis of electrical circuits, heat and mass transfer, fluid dynamics, nuclear physics, process controls, quantum mechanical problems,etc.