To solve the problem of the difficult and slow detection of small defects in magnetic flux leakage (MFL), we propose a fast magnetic flux leakage small defect detection network (FSDDNet). First, we ...introduce COMSOL data augmentation method that utilizes COMSOL simulation software to obtain high-resolution images of defects, which allows the network to capture complete defect features. Furthermore, this method addresses the issue of the relatively monotonic nature of the MFL defect data set used in the experiment. Deep learning networks usually use stride = 2 or max pooling to downsample the feature map, but this method will make the feature map lose some information, and small targets will lose more fine-grained information. Therefore, we introduce an SPD-Conv method to downsample the feature map, which can effectively avoid the loss of information. Meanwhile, an improved C3 network is introduced in the backbone network of FSDDNet. It greatly decreases the computational effort of the network and improves the detection speed. Finally, we add a small target detection head, which effectively improves the small target accuracy. FSDDNet is improved on the basis of YOLOv5, and after the above improvements, FSDDNet obtains very good results in the problem of MFL small defect detection. Experiments show that the accuracy of this algorithm is 95.2% when IOU = 0.5, and the latency is 7.9 ms.
Solid oxide fuel cells (SOFC) are a viable alternative for environmentally-friendly conversion of hydrogen into energy and multiphysics simulation can be used to diminish the experimental effort to ...improve their efficiency. However, an appropriate model of the involved processes and their parameters must be chosen. This paper studies the effects of choice between Maxwell–Stefan and Fick’s law models, and uncertainty of electrode ionic conductivity σion and anodic reference exchange current density i0,ref,f, on cell performance as implemented in the COMSOL Multiphysics® software. In the case of Maxwell–Stefan, peak average power output increased by 21.9% as σion varies from 10−3 to 10−1 S/cm, while the model based on Fick’s law shows an increase of 55.2%. The Maxwell–Stefan model exhibits an increase in peak power of 6% as i0,ref,f ranges from 0.4 to 0.8 A/cm2, and the Fick’s law model an increase of 8.2%. The dependence of the Maxwell–Stefan model on σion is characterized as logarithmic in the studied range. The Maxwell–Stefan model is deemed preferable because its lower sensitivity to the studied parameters helps mitigate uncertainty. It is concluded that despite its limitations, multiphysics modeling is a useful tool for directing research on SOFC materials owing to its descriptive potential.
Display omitted
•Simulation of SOFC in COMSOL Multiphysics® using uncertain parameters.•Mass transfer modeled by Maxwell–Stefan or Fick’s law on the same experimental data.•Maxwell–Stefan model is less sensitive to parameter value fluctuations.•Logarithmic dependence of Maxwell–Stefan power curve on electrode ionic conductivity.
Display omitted
•Ni phyllosilicate was firstly synthesized by a modified microwave synthesis method.•Surfactant modification led to ultrahigh specific surface area of 535 m2 g−1 and ultrathin layer ...of Ni phyllosilicate of only 1.43 nm.•Hexadecyl trimethyl ammonium bromide showed higher promotion effect compared with P123 and F127.•The special structure resulted in competitive catalytic activity for CO2 methanation.•This catalyst could exhibit high stability for 100 h in a long-term test.
The traditional techniques for the synthesis of nickel phyllosilicates usually time-consuming and energy-intensive, which often lead to the formation of layers with excessive thickness due to uncontrolled crystal growth. In order to overcome these challenges, this work introduces a microwave-assisted synthesis strategy to facilitate the synthesis of Ni-phyllosilicate-based catalysts within an exceptionally short duration of only five minutes, attaining a peak temperature of merely 102 °C. To enhance the specific surface area and to increase the exposure of active sites, an investigation was conducted involving three surfactants. The employment of hexadecyl trimethyl ammonium bromide (CTAB) has yielded remarkable results, with an ultrahigh specific surface area reaching 535 m2 g−1 and an ultrathin lamellar thickness of 1.43 nm. The catalyst exhibited an impressive CO2 conversion of 81.7 % at 400 °C, 60 L g−1 h−1, 0.1 MPa. It also demonstrated a substantial turnover frequency for CO2 (TOFCO2) of 5.4 ± 0.1 × 10−2 s−1, alongside a relatively low activation energy (Ea) of 80.74 kJ·mol−1. Moreover, the catalyst maintained its high stability over a period of 100 h and displayed high resistance to sintering. To further elucidate growth temperature gradient of the catalyst and concentration gradient of the materials involved, COMSOL Multiphysics (COMSOL) simulations were effectively utilized. In conclusion, this work breaks the limitation associated with traditional, laborious synthesis methods for Ni-phyllosilicates, which can produce materials with high surface area and thin-layer characteristics.
Electrodeposited amorphous alloys require numerous nuclei and irregular atomic arrangements. In this study, the impact of processing parameters (e.g., a nanosecond laser) on the current density in ...the electroplating solution for an electrodeposited NiP coating was tested using an electrochemical workstation. In addition, the effect of the laser on the temperature and micro-stirring caused by cavitation was simulated using COMSOL (version 5.4). The surface quality, wear, and corrosion resistance of the NiP coating prepared by laser-assisted electrodeposition (LECD) at different laser repetition frequencies (picosecond laser, 0.5, 1, 1.5, 2, and 2.5 MHz) were evaluated. The results showed that the stability of current change was best when the laser frequency, pulse width, scanning line spacing, and irradiation area were 1 MHz, 200 ns, 20 μm, 1 mm2, respectively. Excessive laser energy destroys the balance of electrochemical deposition process. The simulation results showed that the maximum instantaneous temperature of the laser-irradiated solution was 123 °C. Cavitation increases the flow rate of the solution and produces a jet impact on the substrate. The maximum velocity and instantaneous pressure were 0.13 m/s and 7.26 × 108 Pa at 0.1 ns, respectively. At the laser frequency of 0.5 MHz, the P content increases by approximately 2% compared to that of the coating prepared by LECD (1–2.5 MHz). The residual internal stress decreased with increasing frequency, and it existed in the form of tensile stress. The wear and corrosion resistances of the NiP coating were the best when the laser frequency was 1 MHz.
Display omitted
•Laser irradiation increases the current density of ECD.•Laser irradiation has a force impact on the solution.•Cavitation accelerates the flow velocity of solution and form jet impact.•Laser frequency affects the quality of electrodeposited layer.
•3D-printed g-C3N4 interphase realizes dendrite-free growth and anticorrosion.•The DFT proves lower energy barrier to further induces uniform of Zn distribution.•The simulation suggests that g-C3N4 ...can effectively facilitate electric distribution.•The Zn/C3N4//AC supercapacitor and Zn/C3N4//MnO2 battery show excellent stability.
Further commercial deployment of Zn anode has been severely restricted by the notorious tip-induced dendrite growth. The solutions establishing effective zincophile interphase have been proposed to conquer this difficulty. Yet, how to effectively construct zinc deposition interphase is challenging. Herein, we construct a zincophile interphase based on 3D-printed g-C3N4 modulating interface to concurrently achieve homogeneous zinc nucleation and a dendrite-free growth. The Zn/C3N4 anode affords lower the energy barrier and more homogeneously charge distribution to facilitate highly reversible Zn plating/stripping. The symmetric Zn/C3N4 cell presents appreciably low voltage hysteresis and superior cycling stability compared to the bare Zn. Furthermore, the Zn/C3N4//AC supercapacitor and Zn/C3N4//MnO2 battery show long cycle stability. The novel strategy of 3D-printed modulating coatings is straightforward and scalable and provides the design concept to the realization of the long-life aqueous zinc metal batteries.
The flow rate of coolant and the particle beam current are important when high beam current irradiations are intended for production of radionuclides. The beam current on natCu target to produce 63Zn ...via the natCu(p,n)63Zn reaction was investigated and the beam current was obtained more than 350 μA that is the maximum allowed beam current used for producing medical radioisotopes in Nuclear Science and Technology Research Institute of Iran. In addition, the temperature distribution on the target under the different cooling water flow rates has been simulated based on finite element analysis program. The results show that the cooling water flow rate can be brought down to 1.5 L/min without the risk of melting of target material and boiling water.
•The beam current on natCu target to produce 63Zn via the natCu(p,n)63Zn reaction has been numerically analyzed.•The optimum thickness of natCu target is calculated from the nuclear cross-section data and SRIM-2013 calculation.•The highest proton current to produce 63Zn radionuclide was estimated.•To determine the optimal design of the target, the distribution of temperature was calculated using the COMSOL program.
•A new coupled peridynamic (PD) model for combined galvanic corrosion and fracture.•A new analytical calibration replaces earlier method based on computing a “trial-solution”.•Corrosion in two ...different galvanic couple matches well with experiments.•Models based on PDEs require a change in geometry at the interface; the PD model does not.•Failure of a galvanic couple subjected to combined corrosion and stress is simulated.
A coupled peridynamic (PD) corrosion-fracture model is introduced, in which the local corrosion rate is determined by solving the corresponding electrostatic problem. By being able to consider variable distributions of corrosion rates along the anodic surface, the model is particularly useful for simulating galvanic corrosion. A novel analytical calibration for parameters in the corrosion model is provided. The corrosion model is verified in terms of the electric potential, current density, and corrosion depth, and validated against experimental results for AE44 (Mg alloy) – mild steel and AE44 – AA6063 (Al alloy) galvanic couples taken from the literature. The PD results are also compared with those from a COMSOL FEM-based model. It is found that an artificial initial “step-down” in geometry at the galvanic joint is required for the COMSOL model in order to provide reasonable results, but it is not needed in the PD model. A coupled galvanic corrosion-fracture problem accounting for the combined electro-chemical attack and strains induced by mechanical loadings is solved.
Display omitted
Display omitted
•The optimum thickness of Sb2S3 is 350 nm and for Sb2Se3 is 760 nm.•The optimum metrics of tandem solar cell are: Jsc = 16.32 mA/cm2, Voc = 1.48 V, FF = 60.7 %, PCE = 14.66 %.•The ...optimum acceptor density and bulk defect density in Sb2S3 and Sb2Se3 are: NA = 8.9 × 1015 cm−3 and BDD = 7.21 × 10−15 cm−3.•The optimized radiative recombination rate in Sb2S3 and Sb2Se3 layers are 0.73 × 10−10 cm3/s and 6.5 × 10−11 cm3/s, respectively.
A device simulation presented for a tandem solar cell of Sb2S3 and Sb2Se3 as top (Eg = 1.7 eV) and bottom (Eg = 1.2 eV) absorber layers. We examined the device characteristics, radiative recombination, and optimum thickness of this tandem cell using filtered spectrum analysis and current-matching techniques in COMSOL. An open-circuit voltage of 1.58 V, current density of 15.50 mA/cm−2, fill factor of 56.90 %, and a remarkable efficiency of 14 %. The optimum thickness of Sb2S3 is 350 nm and for Sb2Se3 is 760 nm. Promising characteristics obtained with a Jsc = 16.32 mA/cm2, Voc = 1.48 V, FF = 60.7 %, and an overall power conversion efficiency of 14.66 %. The optimum acceptor and bulk defect density have been calculated to be NA = 8.9 × 1015 cm−3 and BDD = 7.21 × 10−15 cm−3. The optimized values of radiative recombination rate in Sb2S3 and Sb2Se3 are 0.73 × 10−10 cm3/s and 6.5 × 10−11 cm3/s, respectively.
