Simulation Verification Research Articles

A true double-body method based on porous media model for simulation and froude scaling verification of an aquaculture vessel resistance

A blueprint of a novel aquaculture vessel composed of rectangular cylinders, pontoons, and nets with the capacity for self-propulsion was drawn. However, when completely different flow features are caused by non-stream shapes, resistance prediction cannot be accurately performed through conventional ship model experiments as the existing scale rules may be invalid. Besides, the existence of nets creates obstacles not only in model tests but also in numerical simulations. Therefore, resistance evaluation of the vessel with nets is very challenging. Porous media model for nets is one of feasible solutions and was validated by previously published experimental results, although a control volume was required. However, porous media model is incompatible with volume of fluid multiphase, which makes the double-body method adopted inevitably. A literally true double-body method based on porous media model was proposed. The comparison of vessels with and without a net exhibited a beneficial interaction between the net and the vessel hull, especially for nets with higher solidity. Furthermore, the Froude scaling law was adopted based on the hypothesis of Reynolds number invariance. All the full-scale resistances predicted by it in seven scale ratios demonstrated satisfactory consistency, and the relative errors grew with the increase of the scale ratios.

Fault probability identification method for distribution networks based on mov-MF distribution

To address the fault identification challenge in distribution networks, a method leveraging a mixture of the von Mises–Fisher (mov-MF) distribution model for fault probability identification is proposed. Initially, the synchronous phasor measuring unit is employed to gather the post-fault steady-state voltage phase quantities, and then, the voltage phase angle values are combined to form a three-dimensional feature quantity. Subsequently, the mov-MF distribution model is initialized through the spherical K-means algorithm and the minimum message length algorithm. This model is further refined via the expectation–maximization algorithm to iteratively optimize distribution parameters. The test set data are input into the mov-MF distribution model, which has been constructed using typical fault data, to discern fault types. Finally, the efficacy of the proposed method is validated through simulation verification conducted on the IEEE 33-node distribution system. The analysis of the examples demonstrates the accuracy of the mov-MF distribution model-based fault identification method in identifying single-phase ground, two-phase ground, two-phase interphase, and three-phase short-circuit faults.

Phase-locking-free all-optical matching system for 100 Gbaud QPSK optical signal.

Photonic firewall is a monitoring protection device that will directly detect and locate optical network attacks at the optical layer, which can effectively ensure the security of optical networks. An all-optical matching system is the core part of photonic firewall, which determines the performance of a photonic firewall, so it is of great significance to research and develop all-optical matching system for high-speed and high-order modulation formats signals. At present, an all-optical matching system for binary modulation formats is relatively mature, but the all-optical matching system for high-order phase modulation format signals is still limited by how to solve the problem of phase synchronization. In this paper, a new all-optical matching system based on self-interference matching is proposed for quadrature phase shift keying (QPSK) optical signal, which avoids the introduction of local target sequence optical signals and phase-locking circuits. The theoretical analysis and simulation verification are conducted for the designed system. The results demonstrate that the system can accurately identify and locate 4-symbol or 8-symbol target sequences in the input QPSK optical signals with 16-symbol and 32-symbol data sequences at a data rate of 100 Gbaud.

Design of air-breathing supersonic vehicle guidance law for intercepting the high maneuvering target with impact angle constraint

Abstract To achieve interception vehicles that can intercept high maneuvering targets with impact angle constraint, and improve the strike effectiveness of the vehicle, based on the two-dimensional planar motion model of the vehicle and the target, this article proposes a sliding mode control vehicle guidance law. The stability of the guidance law is verified through the Lyapunov function, and an extended state observer is set to check for disturbances. After simulation verification, the guidance law can intercept the target with predetermined terminal angle constraints and has good tracking performance.

0.8-V Enhanced bulk-driven folded cascode amplifier with high gain-bandwidth and slew rate

In this study, the proposed bulk-driven amplifier utilizes the bulk-driven flipped voltage follower together with the auxiliary amplifier to form the adaptive biasing input stage. The quasi-floating gate technique to build the class-AB output stage can enhance the gain-bandwidth, DC gain and slew rate of the conventional bulk-driven counterpart. Therefore, the current efficiency is improved. Simulation verification using a 0.18 μm CMOS technology, with a supply voltage of 0.8V, showed a DC gain of 76.6 dB, a CMRR of 106.6 dB, a gain-bandwidth product of 6.78 MHz and an average slew rate of 3.48 V/μs .

Decentralised [formula omitted] robust control of MTMDs for mitigating vibration of a slender MDOF floor configuration

In this research, a novel robust decentralised H (H∞ and H2) design combined with a pattern search method (PSM), incorporating considerations of multiple modal dynamics, was developed to address the vibration issue in slender structures. To verify the effectiveness of the concept, a full-scale laboratory reconfigurable multiple degrees of freedom (MDOF) test-bed floor panel structure was selected, equipping with a passive multiple-tuned mass damper (MTMD) as a coupling system. The optimal parameters of the MTMDs were tailored using the decentralised H design and the PSM, considering the dynamic engagement of multiple modes. Furthermore, a crucifix-type configuration of 2DOF MTMDs was proposed to mitigate the vibration of the floor panel structure. Full-scale forced vibration testing (FVT) was conducted to validate the dynamic performance of the 2DOF MTMDs. The test results provide satisfactory verification and high-quality curve-fitting testing data for parameter study and dynamic simulation. By examining the field data from the 2DOF MTMDs and performing various numerical simulations and analyses, the control performance robustness of the MTMDs was comprehensively evaluated, considering practical engineering variations such as the number and stiffness of MTMDs, as well as the stiffness and mass of the floor panel structure. As a result, the proposed H control strategies for the MTMDs demonstrated robust control capabilities by effectively dissipating significant amounts of externally applied energy.

Verification and Validation for Large Eddy Simulation of Cavitating Flow Around a Projectile Near the Free Surface

AbstractVerification and validation (V&V) is a helpful tool for evaluating simulation errors, but its application in unsteady cavitating flow remains a challenging issue due to the difficulty in meeting the requirement of an asymptotic range. Hence, a new V&V approach for large eddy simulation (LES) is proposed. This approach offers a viable solution for the error estimation of simulation data that are unable to satisfy the asymptotic range. The simulation errors of cavitating flow around a projectile near the free surface are assessed using the new V&V method. The evident error values are primarily dispersed around the cavity region and free surface. The increasingly intense cavitating flow increases the error magnitudes. In addition, the modeling error magnitudes of the Dynamic Smagorinsky–Lilly model are substantially smaller than that of the Smagorinsky–Lilly model. The present V&V method can capture the decrease in the modeling errors due to model enhancements, further exhibiting its applicability in cavitating flow simulations. Moreover, the monitoring points where the simulation data are beyond the asymptotic range are primarily dispersed near the cavity region, and the number of such points grows as the cavitating flow intensifies. The simulation outcomes also suggest that the re-entrant jet and shedding cavity collapse are the chief sources of vorticity motions, which remarkably affect the simulation accuracy. The results of this study provide a valuable reference for V&V research.

Multiscale periodic homogenization for additive manufacturing of honeycomb lattices

Additive manufacturing (AM) is revolutionizing how we create things, offering innovative solutions that rival traditional manufacturing methods. In Fused Filament Fabrication (FFF), incorporating continuous fiber-reinforced filaments has significantly enhanced mechanical properties, making them valuable across diverse sectors like aerospace, automotive, and robotics. However, before printing a part, numerical simulation for design verification is essential. Yet, there’s a lack of suitable tools for modeling the complex material properties, particularly for composite lattice structures. To address this, we propose a three-level periodic homogenization method. The first level focuses on modeling individual filaments, followed by characterizing inter-bead voids at the second level, and finally, modeling collective lattice behavior at the third level. Hexagonal cellular lattice composite structures were modeled and tested to confirm the method’s accuracy and its value in supporting simulation and modular design for the composite FFF process.

Design and simulation of system to prevent runway overrun during landing of civil aircraft

Abstract The airborne runway overrun prevention system predicts landing distance by utilizing real-time aircraft status parameters obtained through onboard sensors. This system offers early warnings to pilots, thereby enhancing flight safety. This paper introduces a design scheme for a runway overrun prevention system considering aircraft dynamic performance. Initially, the study analyzes the basic components and functional requirements of the system based on the Minimum Operational Performance Standard For A Runway Overrun Awareness And Alerting System by the European Aviation Safety Agency. Subsequently, the approach and landing phases are segmented into four stages, providing a methodology for calculating landing distance using a dynamic model. Finally, concluded with a simulation verification conducted on the X-Plane flight simulation platform, we test the visual alarm system of the proposed runway overrun prevention system. Simulation results demonstrate that, during the landing phase, the system dynamically calculates and updates stopping points for each braking mode based on the current braking method. In situations where there is a risk of runway overrun, the system issues timely and well-founded alarms.

Research on a new method of islanding detection based on lifting wavelet and neural network

Abstract At present, the commonly used active and passive islanding detection methods have their own shortcomings, and the islanding detection effect is difficult to meet the requirements. Therefore, a new detection method based on wavelet signal processing and artificial intelligence to identify islanding is proposed in this paper. In this method, the feature quantities required for islanding detection are obtained by wavelet transform and signal processing, and then the feature quantities are identified by neural network to determine whether the islanding is generated in distributed generation system. Wavelet transformation has a strong ability of signal feature extraction, while the neural network has strong learning and identification abilities, the combination of the both is beneficial to improve the success rate of islanding detection. Simulation verification shows that the new islanding detection method proposed in this paper can detect islanding quickly and accurately, and the performance of islanding detection has been significantly improved.

Study on the Design of Valve Base Insulation and Power Supply Transformer for High-Voltage DC Circuit Breaker

Abstract High-voltage DC circuit breaker is a key piece of equipment to building DC power grids. DC circuit breakers need to support and isolate from high voltage to ground through valve-based equipment and use valve-based power supply transformer to continuously supply energy to high potential components, the electrical performance of these two equipment determines whether DC circuit breakers and DC networks can be operated safely and reliably. For this reason, this paper carries out the research on the insulation capability of the valve base and the performance of the power supply transformer, such as the design and simulation of electric and thermal fields, as well as the test program. Firstly, the insulation design and simulation study of the valve base as a whole is carried out, and the design optimization of the equipotential scheme of the top homogeneous tubular bus, diagonal pull insulator and hydroelectric pole is completed. Secondly, the design and simulation verification of the thermal field distribution of the energy-supply transformer, the overvoltage between the ends of the output windings and the optimization scheme, and the short-circuit impedance were carried out. Finally, the insulation performance of the valve base, the temperature rise of the energy supply transformer, the overvoltage simulation of the output winding and the short-circuit characteristics were tested. The results show that: after optimization, the maximum field strength of the homogenizer is 2.3kV/mm, and the overall maximum field strength of the valve base is 2.61 kV/mm on the diagonal insulator, and there is no pressure difference between the water circuit and the fittings using the three-pin vertically distributed hydropower electrode scheme; the temperature rise of the supply transformer in the simulation and the actual measurement is 27K and less than 30K; by means of the parallel connection of the MOV, the overvoltage of the output winding of the power supply transformer under voltage impulse is effectively reduced to -1.8kV; the measured short-circuit impedance of the power supply transformer is 69.5%. The optimized design of DC circuit breaker valve base and power supply transformer can operate safely, and effectively support the construction of DC circuit breaker and DC power network.

A sustainable Poly (deep eutectic solvents) based molecular imprinting strategy with experimental and theoretical elucidation: Application for removal of atrazine in agricultural wastewater

In this research, a fabrication of Poly(deep eutectic solvent) composed of choline chloride-methacrylic acid (ChCl-MAA) was developed to cross-link and polymerize through molecular imprinting technology (MIT). The results were analyzed using a simple syringe solid phase extraction (SPE) device combined with Poly(DES)-MIT strategy, with the aim of specifically removing atrazine (ATZ) from agricultural wastewater. Density functional theory was applied for the rapid prediction of optimal molar ratio (1:4) between the template (ATZ) and monomer (DES), yielding highly consistent results with experimental findings. The electrostatic potential (ESP) distributions and the independent gradient model (IGMH) were employed to investigate the types and strengths of weak interactions in Poly(DES). Due to the participation of DES in the polymerization reaction, Poly(DES) exhibited rapid adsorption equilibrium time (120 min) and excellent specificity recognition ability (selectivity factor of 14.02). The HPLC-DAD analysis system exhibited a good linear response in the range of 0.5∼500 mg L−1, with a detection limit (LOD) of 0.26 mg L−1 and a quantitation limit (LOQ) of 0.87 mg L−1. The admirable feasibility for the removal of ATZ (with a recovery rate of 99.93 %) from real agricultural wastewater substantiated the outlook of practical application of Poly(DES)-MIT strategy. In addition, the adsorption rate of Poly(DES) on ATZ only decreased by 5.80 % (from 96.60 % to 90.80 %) after five adsorption–desorption cycles, demonstrating its significant sustainability. This study combined computer-aided design with a novel green DES-mediated polymerization process to construct an environmentally friendly adsorbent with high selectivity for ATZ. From a quantum chemistry perspective, it was demonstrated that Poly(DES) selectively captures ATZ from agricultural wastewater mainly through hydrogen bonding interactions and van der Waals forces. The combined method of theoretical simulation and experimental verification showed vast potential in the field of safe cultivation of medicinal herbs and crops, opening up new possibilities for the precise monitoring of other pollutants in the environment.

A Study on Fault Localization Method of Three-Terminal Multi-Section Overhead Line–Cable Hybrid Line Using MEEMD Combined with Teager Energy Operator Algorithm

An improved fault localization method combining total aggregate empirical modal decomposition (MEEMD) and Teager energy operator (TEO) is proposed to address the fault localization issue of three-terminal multi-segment overhead line–cable hybrid transmission lines. This method solves the fault localization problem caused by wave impedance discontinuity in hybrid lines. First, the MEEMD algorithm, which improves modal aliasing, and the Teager energy operator, which reflects transient energy changes, are combined for the accurate detection of faulty traveling wave heads. The fault line section determination condition within the fault branch is used to determine the overhead line section or cable section where the fault is located after determining the faulty branch line. This condition is based on the time difference between the initial traveling wave of the fault arriving at each end measurement point and the T-node. Ultimately, the fault distance is determined using the double-ended traveling wave technique. By combining PSCAD and MATLAB for simulation verification, the accuracy of the ranging method is compared and analyzed, and the results show that the method is able to ensure the accuracy of ranging at different fault locations and transition resistances. Additionally, the localization error is basically kept within 30 m, which significantly improves the accuracy of fault localization.

Trajectory tracking control of wearable upper limb rehabilitation robot based on Laguerre model predictive control

Wearable rehabilitation robots have become an important auxiliary tool in rehabilitation therapy, providing effective rehabilitation training and helping to recover damaged muscles and joints. In response to the difficulty of traditional control methods in solving various constraints in the trajectory tracking process of the Upper Limb Rehabilitation Robot (ULRR), this study uses model predictive control to study the trajectory tracking problem of the upper limb rehabilitation robot. Firstly, based on the Lagrangian dynamic model of wearable rehabilitation robots, an extended state space model with pseudo linearization of the system was established. Given the performance indicators and various constraints of the system, a corresponding model predictive controller is designed based on the Laguerre model to ensure system performance while greatly reducing the computational complexity of predictive control. Secondly, the stability of the model predictive controller is demonstrated, and a disturbance observer is introduced into the controller to achieve compensation for slow-varying perturbations; a joint space sliding mode variable is also introduced to achieve simultaneous tracking of the joint’s desired position and desired velocity. Finally, taking a planar two bar robot as an example, comparative simulation verification was conducted on unconstrained joint trajectory tracking and constrained joint trajectory tracking. The simulation results show that the model predictive controller can achieve simultaneous tracking of joint expected trajectory and expected speed while meeting various constraints. It has good effects in improving patient motion control ability and reducing patient fatigue, providing new research ideas and methods for the field of rehabilitation therapy.

Molecular insights into chronic atrophic gastritis treatment: Coptis chinensis Franch studied via network pharmacology, molecular dynamics simulation and experimental analysis

Chronic atrophic gastritis (CAG), characterized by inflammation and erosion of the gastric lining, is a prevalent digestive disorder and considered a precursor to gastric cancer (GC). Coptis chinensis France (CCF) is renowned for its potent heat-clearing, detoxification, and anti-inflammatory properties. Zuojin Pill (ZJP), a classic Chinese medicine primarily composed of CCF, has demonstrated effectiveness in CAG treatment. This study aims to elucidate the potential mechanism of CCF treatment for CAG through a multifaceted approach encompassing network pharmacology, molecular docking, molecular dynamics simulation and experimental verification. The study identified three major active compounds of CCF and elucidated key pathways, such as TNF signaling, PI3K-Akt signaling and p53 signaling. Molecular docking revealed interactions between these active compounds and pivotal targets like PTGS2, TNF, MTOR, and TP53. Additionally, molecular dynamics simulation validated berberine as the primary active compound of CCF, which was further confirmed through experimental verification. This study not only identified berberine as the primary active compound of CCF but also provided valuable insights into the molecular mechanisms underlying CCF’s efficacy in treating CAG. Furthermore, it offers a reference for refining therapeutic strategies for CAG management.

Quantum model prediction for frequency regulation of novel power systems which includes a high proportion of energy storage

As the proportion of renewable energy generation continues to increase, the participation of new energy stations with high-proportion energy storage in power system frequency regulation is of significant importance for stable and secure operation of the new power system. To address this issue, an energy storage control method based on quantum walks and model predictive control (MPC) has been proposed. First, historical frequency deviation signals and energy storage charge–discharge state signals are collected. Simulation data are generated through amplitude encoding and quantum walks, followed by quantum decoding. Subsequently, the decoded data are inputted into the MPC framework for real-time control, with parameters of the predictive model continuously adjusted through a feedback loop. Finally, a novel power system frequency regulation model with high-proportion new energy storage stations is constructed on the MATLAB/Simulink platform. Simulation verification is conducted with the proportional–integral–derivative (PID) and MPC methods as comparative approaches. Simulation results under step disturbances and random disturbances demonstrate that the proposed method exhibits stronger robustness and better control accuracy.

Optical transmission trajectories in single tapered fibers of TOFA by numerical simulation and experimental verification

Tens of millions or billions of single tapered fibers are independent optical transmission elements of tapered optical fiber array (TOFA) for imaging. The optical transmission trajectories of these single tapered fibers, which directly affect imaging qualities of TOFA, are rarely analyzed. This paper provides a method to numerically simulate it for fibers located at different positions along the radial direction of TOFA. The tapered curves of TOFA were firstly simulated by Finite Element Analysis (FEA) software and experimentally verified by the same preparation parameters. It is shown that the slope of tapered curve increases with stretching length. Meanwhile, the taper angle gets greater, and the profile of tapered deformation zone expands outward, while the radius of straight zone remains stable. Based on these, the optical transmission trajectory of single tapered fibers located from center to edge in TOFA was simulated, and then further verified by a self-developed instrument. Both simulation and experiment illustrate that the relative transmittance of single tapered optical fiber is decreased along the radial direction within the same TOFA. In comparison with the transmittance of the central axial fiber, the simulated and experimental unevenness on relative transmittance of peripheral fibers is within 7.11% and 9.74%, respectively. With the relative transmittance at the central position of the optical fiber being identical, the difference of relative transmittance (ΔT) between the simulation and experiment is gradually increased from center to peripheral regions along the radial direction of TOFA, reaching the maximum ΔT of 4.23%. The simulated results are well in agreement with the experimental ones.

A contactless energy transfer type of 3-DOF ultrasonic tool holder

The vibration form of the tool has a significant impact on the machining effect in rotary ultrasonic machining. Compared with 1DOF rotary ultrasonic machining, multi-DOF rotary ultrasonic machining have comprehensive advantages in the machining performance. However, the current multi-DOF rotary ultrasonic machining faces the challenges of miniaturization, multi-DOF vibration integration and high rotary speed. Therefore, a 3DOF ultrasonic vibration tool holder with decoupled three-channel contactless energy transfer was proposed, which realize 1DOF, 2DOF and 3DOF rotary ultrasonic machining with the same resonant frequency and the vibration conversion functions at high rotation speed. Structure design, principle analysis and simulation verification was carried out to determine the structure size and material. Through manufacturing and testing of prototype, the results show that under the performance of high speed, high transfer efficiency with 93 % and low temperature rise. The prototype of 3DOF ultrasonic vibration tool holder can not only integrate six vibration forms with high amplitude, but also has the function of replacing the milling tool for metal and grinding tool for brittle materials. Finally, through machining experiments with different vibration forms, two kinds of elliptical vibration produce regular textures with different shapes in the Ti-6Al-4V milling. In Al2O3 grinding, the surface roughness is the lowest under 2DOF vertical elliptical vibration grinding. While the 2DOF horizontal elliptical vibration grinding significantly improves the chip removal and prolongs the tool life. These findings provide guidance for machining performance under various vibration mode. It was proved that this tool holder integrated and switch with multiple vibration modes is of great value for high efficiency and high-quality multi-procedure machining.

Active Disturbance Rejection Control of Permanent Magnet Synchronous Motor Based on RPLESO

In view of the problem of the low-speed jitter of household lawn mowers driven by a permanent magnet synchronous motor (PMSM) at low speeds and high torque, and the complicated parameters of traditional non-linear active disturbance rejection controllers, a partially optimized linear active disturbance rejection control (LADRC) driving PMSM strategy is proposed. First, the linear extended state observer (LESO), which bears a significant burden in terms of speed and load estimation in active disturbance rejection control, is optimized by reducing its order to improve the anti-disturbance performance of the active disturbance rejection controller within a limited bandwidth. Secondly, the reduced-order parallel linear extended state observer (RPLESO) is obtained by optimizing the parallel structure of the order-reduced LESO, which improves the control precision and robustness of the system. Through a simulation and experimental verification, the optimized LADRC control of the PMSM system is shown to improve the parameter adjustability, speed estimation precision and system robustness.

Parameter Calibration of Discrete Element Model of Wine Lees Particles

In order to investigate the contact characteristics of the mechanical parts of the brewing robot with wine lees particles, it is essential to calibrate the parameters of the discrete elemental model of wine lees particles. This paper proposes a method based on tests of the angle of repose. The simulation test is conducted to establish a regression model and combined with physical tests to find optimization. The contact model used in simulation modeling is Hertz-Mindlin with Johnson-Kendall-Roberts. Not all discrete element model parameters of wine lees particles have a significant impact on the angle of repose, so screening through Plackett-Burman Design is performed. The results indicate that the restitution coefficient between wine lees particles and restitution coefficient between wine lees particle and steel plate have a significant impact on angle of repose. Additionally, another parameter that is difficult to obtain, namely surface energy (JKR), also plays a crucial role. The optimal value interval for these three parameters is determined by the steepest ascent test, and a linear regression model for angle of repose is built through Box-Behnken Design. The optimal values obtained are as follows: restitution coefficient between wine lees particles—0.603; restitution coefficient between wine lees particle and steel plate—0.595; JKR—0.083. Finally, in order to verify the accuracy of calibrated parameters, simulation verification tests are carried out which show that there is only a relative error rate at 0.18% between simulated angle of repose and actual angle of repose, indicating that accurate calibration parameters were achieved. This study can provide reference for selecting discrete element model parameters for wine lees particles in future research endeavors.