Parameter Design Method Research Articles

Velocity index and wading height based design method of trajectory parameters for a coupled parallelogram legged walking robot

This paper proposes a novel design method for trajectory parameters based on the velocity index and wading height, which is implemented on a six-legged robot with a coupled parallelogram leg (CPL) for wading scenarios such as shallow waters, harbors, and coastal areas. Design of trajectory parameters includes motion planning and initialization of the joint space angles. The parameters of motion planning are obtained from pre-tests, considering the characteristics of CPL, motor performance, and legged motion. The initial angles of the joint space are obtained using an objective function that considered the velocity index and wading height. By adjusting the coefficients of the objective function, the optimal initial angles of the joint space can be determined for different scenarios, leading to improved overall performance. The proposed approach was validated through experiments using a prototype and provided a reference for setting trajectory parameters in other legged robots.

Analysis of output characteristics of wireless power transfer system based on LCC/S-S hybrid compensation structure

PurposeTo simplify the circuit design and control complexity of the magnetic coupling resonant wireless charging system, the radio energy transmission constant current and constant voltage charging is realized.Design/methodology/approachThe purpose of this study is to simplify the circuit design and control complexity of the magnetic coupling resonance wireless charging system, in order to achieve constant current and constant voltage charging for wireless energy transmission. First, the principle of LCC/S-S compensation structure is analyzed, and the equivalent mathematical model is established; then, the system characteristics under constant current and constant voltage mode are analyzed, and the design method of system parameters is given; finally, a simulation and experimental system is built to verify the correctness and feasibility of the theoretical analysis.FindingsThe results show that the proposed hybrid topology can achieve a constant current output of 2 A and a constant voltage output of 30 V under variable load conditions, and effectively suppress the current distortion problem under light load conditions. The waveform distortion rate of the inverter current is reduced from 33.97% to 10.45%.Originality/valueBy changing the high-order impedance characteristics of the compensation structure, the distortion of the current waveform under light load is suppressed, and the overall stability and efficiency of the system are improved.

Robust Optimization of Power System Stabilizer Parameters Based on Pole Placement Technique

To enhance the stability of power system, a power system stabilizer (PSS) is one of the control mechanisms installed in the power plants. A suitable PSS parameters set can help in reducing the power swing. In general, the design of PSS parameters is performed based on a nominal operating condition of the power system. In this paper, a multi‐objective optimization algorithm based on pole placement technique is proposed to find a robust PSS parameters set. The proposed strategy searches for the optimal PSS parameters under multiple operating conditions of the generator. Preliminary simulation results on a single machine infinite bus (SMIB) model show that the proposed PSS parameters design method can further improve the robustness of the overall power systems performance under different types of disturbance. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Virtual Inertia Implemented by Quasi-Z-Source Power Converter for Distributed Power System

This paper proposes a novel virtual inertia control strategy for distributed power systems with high penetration of renewable energy sources. The strategy uses a quasi-Z-source power converter to emulate the inertia response of a synchronous generator by regulating the DC-link capacitor voltage in proportion to the grid frequency deviation. This paper analyzes the effect of inertia on the frequency regulation of a single-area power system and derives the parameter design method and limitations of the virtual inertia. The paper also introduces the working principle and modulation technique of the quasi-Z-source power converter and presents the virtual inertia control scheme based on a voltage-frequency controller. The paper verifies the feasibility and effectiveness of the proposed strategy through MATLAB/Simulink simulations and dSPACE semi-physical experiments. The results show that the proposed strategy can reduce the frequency deviation and rate of change of frequency (RoCoF) by 20% and 50%, respectively, under load disturbances. The paper demonstrates that the quasi-Z-source power converter can provide flexible and adjustable virtual inertia for distributed power systems without additional energy storage devices.

Controller parameters design of a fractional‐order LCL‐type grid‐connected inverter

SummaryThe grid‐connected inverter (GCI) based on the fractional‐order LCL (FOLCL) filter can achieve good attenuation of resonant peak and simplify the control system design by omitting the capacitor current feedback as long as the orders of the inductor and capacitor are set appropriately. This paper investigates the parameter design methods of four types of controllers based on a single‐phase FOLCL‐type GCI without capacitor current feedback; the four controllers are the integer‐order proportional integral controller, fractional‐order proportional integral controller, integer‐order proportional resonance controller, and fractional‐order proportional resonance controller. Closed‐loop constraints based on steady‐state error, phase margin, and gain margin are given to design the specific parameters of each controller. The methods can accurately and quickly obtain the appropriate controller parameters to meet the system performance requirements without repeated trial and error. Simulations and hardware‐in‐the‐loop experiments verify the validity of the theoretical analyses.

Dynamics modeling and experiment validation for piezoelectric-transmission-wing system

Aiming at the challenge of predicting the dynamic behavior of the flapping wing in the piezoelectric-transmission-wing (PTW) wingbeat system, a lumped-parameter model coupling piezoelectric structural mechanics and flapping-wing aerodynamics is proposed to address the challenge caused by the fluid-structure interaction (FSI). Firstly, a model describing the piezoelectric mechanical response is established, which has the ability to better predict the mechanical response of the piezoelectric actuator under high electric field and low-frequency driving conditions. In order to verify the validity and accuracy, tip deflection, stiffness and blocking force experiments as well as data comparisons are performed to substantiate the findings. Secondly, a comprehensive and reasonable lumped-parameter dynamic model is constructed based on the analysis of the transmission mechanics based on pseudo-rigid-body theory and the improved aerodynamic modeling of the wing, along with the aforementioned piezoelectric mechanical modeling. Thirdly, simulation and dynamic response experiments of the wingbeat system are carried out. Results show that the simulation data are in good agreement with the experimental values, which indicates the accuracy of the model in predicting the dynamic behavior of the flapping wing powered by the piezoelectric actuator. Moreover, some interesting phenomena such as the pitch oscillation of the wing and the dependence of the flapping motion on the driving frequency have been demonstrated in the simulation and the wingbeat experiment, respectively. The research findings of this article offer three types of assistance: (1) providing a parameter design method for piezoelectric actuators to achieve the desired mechanical response; (2) predicting and explaining the dynamic behavior of the PTW wingbeat system; and (3) providing a theoretical foundation for the parameter design and optimization of the wing-actuator pairing in the flapping wing system.

Parametric design for custom-fit eyewear frames

More than half of the people on the planet use eyewear to correct or protect their vision. Eyewear products that fit poorly cause discomfort, dizziness, or blurred vision. One method to improve fit is to create custom-fit eyewear frames on an individual basis. In this paper we propose a new parametric design method to customize the eyewear frames based on individual 3D scanned data of head-and-face measurements. We take the eyeglasses frame as the case study to establish the landmark-product relationship and develop the parametric algorithm in Rhino/Grasshopper software. The results of the case study can generate custom-fitted eyeglass frame models for the two selected subjects, one 33% percentile Asian female and one 90% percentile Caucasian male. The future study will continue validating the eyewear frame fit and optimizing the parametric design method.

Tunable Acoustic Properties in Reconfigurable Kerf Structures

Freeform structures are appealing in architecture owing to their ability to combine pleasing aesthetics and functionality. Regarding architectural functionality, freeform structures have the potential to meet desired acoustic requirements in indoor architecture through the proper design of materials and geometries. Kerfing is one of the practical methods to generate reconfigurable freeform structures from rigid planar construction materials. This study aims to explore tunable room acoustic characteristics through the use of kerf structures. In this study, we investigate acoustic responses of kerf structures made out of a medium density fiber board having a hexagon spiral kerf pattern with varying cut densities. Experiments are conducted to measure the acoustic properties (e.g., absorption coefficient) of the kerf unit cells with different cut densities. We then design kerf patterns using the parametric design method and explore the flexibility of kerf structures with different kerf cut densities. We model the kerf structures of varying kerf cut density and shape reconfigurations and use a ray-tracing simulation to study their impacts on the acoustic performance, i.e., reverberation times, of a small office space. Overall, this study leverages the unique attributes of kerf structures such as different cut densities and shape reconfigurations to tune the room acoustics in addition to their usage in indoor architectures due to their pleasing aesthetics.

Study on the effect of photovoltaic louver shading and lighting control system on building energy consumption and daylighting

ABSTRACT Photovoltaic louver shading (PLS) and lighting control system (LCS) can both reduce energy consumption during building operation, but when used in combination, PLS may reduce indoor daylighting and increase lighting energy consumption, which is not good for the LCS. In order to reduce the energy consumption of building operation, this paper adopts the parametric performance design method, uses the Grasshopper platform and Ladybug tools to establish a one-click simulation process, and analyzes the energy-saving potential and daylighting impact of the combined use of PLS and LCS in Qingdao. It was found that the annual energy efficiency of the PLS can reach 15%, and LCS can save about 50% energy of lighting in a year, producing an energy efficiency at 14%. In the meantime, using both the PLS and LCS throughout the year can save up to 22.8%. When using only LCS from December to February, and using both PLS and LCS from March to November can save up to 24.14%.

Improved Single-Phase UPQC With Integrating Auxiliary Capacitor for Power Rating Reduction

Unified Power Quality Conditioner (UPQC) can well achieve comprehensive control for power quality. However, the power rating reductions of the series side and parallel side of the back-to-back connected converters in UPQC are hard to be achieved simultaneously, and they even restrict each other. In this paper, a new topology of UPQC is proposed. It has an LC filter coupled with an external capacitor at the series part. Besides, a comprehensive coordination strategy is proposed to operate the improved UPQC (iUPQC) at reactive power compensation (RPC) mode and voltage fluctuation compensation (VC). Specifically, to achieve the low power rating, the proposed control strategy makes the series part undertakes partial reactive power that needs to be compensated at the parallel side in RPC mode. At the same time, it makes the parallel side coordinates the series side to expand the optimal operation range in VC mode. Compared with the conventional UPQCs, the iUPQC can well reduce the power rating of back-to-back connected converters from both parallel and series sides. Moreover, the optimal parameters design method is also provided. Finally, the effectiveness of the proposed topology and control method is validated by both simulation and experimental results.

An Efficient Method for the Inverse Design of Thin-Wall Stiffened Structure Based on the Machine Learning Technique

In this paper, a new method using the backpropagation (BP) neural network combined with the improved genetic algorithm (GA) is proposed for the inverse design of thin-walled reinforced structures. The BP neural network model is used to establish the mapping relationship between the input parameters (reinforcement type, rib height, rib width, skin thickness and rib number) and the output parameters (structural buckling load). A genetic algorithm is added to obtain the inversely designed result of a thin-wall stiffened structure according to the actual demand. In the end, according to the geometric parameters of inverse design, the thin-walled stiffened structure is reconstructed geometrically, and the numerical solutions of finite element calculation are compared with the target values of actual demand. The results show that the maximal inversely designed error is within 5.1%, which implies that the inverse design method of structural geometric parameters based on the machine learning and genetic algorithm is efficient and feasible.

An integrated framework for residential layout designs: Combining parametric modeling, neural networks, and multi-objective optimization for outdoor activity space optimization

The quality of life of residents and community vitality is significantly enhanced by outdoor activity spaces within residential areas. Existing residential layout designs primarily focus on a restricted set of predefined layouts and most outdoor evaluation indices are limited to thermal comfort, thereby leading to an incomplete evaluation system. Furthermore, there is a scarcity of studies offering a comprehensive design process, from parameterized generation to performance evaluation. As such, there is a pressing need for an all-encompassing design framework that investigates a broad array of layout possibilities while providing multidimensional evaluations based on diverse metrics, thereby augmenting the accuracy and intelligence of residential layout designs.This research introduces a building layout generation framework that integrates parametric modeling (PD), neural network modeling (ANN), and multi-objective optimization (MOO) methods. The framework utilizes parametric design methods to construct a geometric model that adheres to building codes. Following this, it builds separate neural network models for three key metrics: sky view factor (SVF), sunshine duration, and noise, this approach is aimed at accelerating the evaluation process. This alternative model serves as the objective function for multi-objective optimization, identifying the optimal building layout that balances multiple metrics. Additionally, the framework utilizes the ideal point method to optimize the final Pareto solution set, thereby informing designers' and planners' program selections.Case studies of this framework indicate that the residential layouts generated can adhere to building codes while effectively balancing the three crucial metrics. Relative to the conventional modeling-evaluation process, this framework augments efficiency substantially. The design framework presented herein will offer comprehensive decision support for policy makers to optimize residential layout designs, further fostering the harmonious coexistence of people and cities, while advancing intelligent building design and sustainable urban development.

Adaptive stepsize estimation based accelerated gradient descent algorithm for fully complex-valued neural networks

Nesterov accelerated gradient (NAG) method is an efficient first-order algorithm for optimization problems. To ensure the convergence, it usually takes a relatively conservative constant as the stepsize. However, the choice of stepsize has a great impact on the optimization process. In this paper, two adaptive stepsize estimation methods are proposed for complex-valued NAG algorithm for efficient training of fully complex-valued neural networks. The basic idea of the first one is to adaptively determine suitable stepsize by estimating the local smoothness constant of the loss function with the norm of approximate complex Hessian matrix. Its validity is theoretically analyzed by means of the decomposition of complex matrix. Furthermore, by introducing a new parameter design method for multi-step quasi-Newton condition, an improved stepsize estimation is presented. Experimental results on pattern recognition, channel equalization, wind forecasting and synthetic aperture radar (SAR) target classification demonstrate the effectiveness of the proposed methods.

A Novel Three-Phase Omnidirectional Wireless Power Transfer System With Zero-Switching-Loss Inverter and Cylindrical Transmitter Coil

Aiming at the problems of large switching loss and large output power fluctuation in the existing omnidirectional wireless power transfer (OWPT) system, a novel OWPT system with zero-switching-loss inverter and cylindrical transmitter coil is proposed. By introducing an auxiliary resonant network with simple structure and low-loss on each phase arm of the three-phase inverter, zero-voltage switching (ZVS) turn-ON and zero-current switching (ZCS) turn-OFF within the full power range can be acquired. The switching loss in the main circuit of inverter is reliably eliminated. The transmitter coil is a cylindrical coil composed of the three curved rectangular coils, whose excitation current amplitude is equal and the phase difference is 120°. It can arise a spatial rotating magnetic field around the transmitter coil and provide an omnidirectional energy transmission channel. The operating principle of soft-switching is analyzed in detail, and the design rules of soft-switching in full power range and the parameter design method of coupler to reduce the fluctuation of output power are given. Ultimately, an experimental prototype is used to verify the feasibility of the proposed OWPT system. The experimental results indicate that the system output power is retained at 93.4W∼104.7W and transfer efficiency is retained at 71.2%∼78.1% under arbitrary angular misalignment of receiver.

Seismic performance of concrete-encased hexagonal CFST column base: Design method

This paper presents the parametric analysis and design method for the concrete-encased hexagonal concrete-filled steel tubular (CFST) column base under combined compression and biaxial bending. The corresponding experimental and numerical investigations on the seismic performance of the concrete-encased hexagonal CFST column base under combined compression and biaxial bending have been presented in the companion paper (Yang et al., 2023). The finite element model established in the companion paper is used to study the influence of key parameters on the load bearing capacity and the distribution of internal force. These parameters include those of the CFST column, the outer RC, the plate-anchor component, the axial load ratio and shear connectors. A total of six failure modes are identified, including three types of flexural failure and three types of shear failure. The ultimate capacity and ductility of the column base with flexural failure at the bottom or top of the plate are higher than that of other four failure modes, which are determined as the reasonable failure modes for practical application in the design and analysis of concrete-encased column bases. A novel design approach for the concrete-encased CFST column base is introduced. A simplified method is proposed to predict the flexural resistance of the concrete-encased CFST column base, following up with the shear strength calculation of outer RC to determine the stirrup arrangement. Some constructional recommendations are also proposed.

Fast three-dimensional simulation based on data constraints and methods to improve the realism of knitted sweaters

The purpose of this research is to use the methods of data constraints for parametric design and three-dimensional simulation of knitted sweaters to achieve the purpose of enhancing the simulation effect. First, based on the basic plates of knitted sweaters as a reference, the parameters of the curve parts of the plates were constrained, and the constraint relationships were applied to build the parametric design models. After entering the user parameters, the changed plates can be obtained. On this basis, the transformation of flat plates to three-dimensional surfaces was carried out. The triangular grid mapping relationships between two-dimensional plates and three-dimensional surfaces were constructed, and the physical properties were further specified for the mesh particles. When the surface texture parameters of the two-dimensional plane are designed, the three-dimensional surface will change accordingly. In addition, this research put forward the stitching and matching methods of the seams of knitted sweaters. The joint size was equally divided, and the number of coils was converted into the number of triangular mesh. Point-to-point mesh was used to realize the accurate counterpoint fusion of coils. The feasibility of parametric and virtual design methods was verified by taking an example, which provides ideas for the computer-aided design of knitted sweaters and promotes the improvement of production efficiency without wasting raw materials.

Evaluation of rocking seismic isolation performance of railway tall piers with different energy dissipation devices

Conventional pier top isolation measures cannot reduce the inertial force produced by railway gravity tall piers. This may damage the pier column and pile foundation during strong earthquakes. As an effective pier bottom seismic isolation structure, rocking piers have broad application prospects in railway tall pier bridges. This paper considers five energy dissipation devices (EDDs) to constrain the bottom of a free rocking pier (F-RP), namely buckling restrained braces (BRBs), yielding steel cables (YSCs), self-centering buckling restrained braces (SC-BRBs), superelastic shape memory alloy wires (SMAs), and viscous dampers (VDs). In particular, an additional “locking” structure is proposed to prevent excessive rocking of the piers and protect the EDDs. Parameter design methods are proposed for damage control and residual deformation control of piers. Nonlinear static and dynamic analyses are performed. The results show that the fixed base piers based on the ductility design suffered severe damage during strong earthquakes. The longitudinal rebar strain ratio is recommended as the damage index for the rocking pier due to large axial force fluctuations. Based on the design method proposed in this paper, the additional EDD constraints make the pier's expected damage level controllable and improve the post-earthquake predictability of the railway pier. BRBs and VDs are unfavorable to pier bottom shear forces. YSCs may produce irrecoverable residual deformation, while BRBs may have significant residual stresses. SC-BRBs and SMAs require no post-earthquake repair. SC-BRBs have more potential for application in rocking piers in high-intensity earthquake areas.

Mix design of equal strength high volume fly ash concrete with artificial neural network

High volume fly ash concrete (HVFAC) has been widely used, and the mix proportion of HVFAC is usually designed based on the required compressive strength. Therefore, the research of HVFAC under the condition of equal strength has more engineering application value. However, in the current mix proportion design standard, there is no special discussion on the mix proportion design method of HVFAC. In this study, the compressive strength of HVFAC affected by four factors (water-binder ratio, FA content, curing method and curing age) was systematically studied. Based on 594 sets of strength data obtained from experiments, the method to determine the key mix proportion parameters (water-binder ratio and FA content) of equal strength HVFAC was proposed through machine learning algorithms (ML). Two ML methods (i.e., a multiple linear regression (MLR) and an artificial neural networks (ANN)) were developed to predict the HVFAC compressive strength and then their performances were compared. Through comparison, it was found that the mean absolute error and root mean squared error of the ANN model were both lower than the MLR model, and the ANN model has lower error and higher accuracy. In addition, the reliability of the proposed ANN model was verified with data in other literatures, the results showed the errors between the predicted values and the measured values are lower than 25%. The weight contribution rate of each factor to the strength was calculated. Among the four factors, the curing age had the greatest impact on the compressive strength, which contributes up to 60.3%. The influence degree of FA content is greater than that of water-binder ratio. With the development of curing age, the influence degree of FA content and water-binder ratio on the strength gradually decreases while the curing method increases. Finally, according to the ANN prediction results, the key mix parameters design method for equal strength HVFAC under multi-factor conditions was proposed, which provide guidance for concrete preparation in actual engineering.

Analysis of Energy Transmission and Design of Additional Capacitance for a Novel Secondary Side Parallel LCD Forward Converter

For the deficiency of low utilization ratio of transformer excitation energy, complex circuit structure, low efficiency and low output power in the existing magnetic reset technology, a secondary parallel LCD forward converter which can avoid reverse charging of additional capacitor is proposed. According to the different working modes of inductors in the proposed converter, the converter is divided into different combined working modes, and the working principles of different combined working modes are analyzed in detail. At the same time, the influence of additional LCD circuit on the performance of the proposed converter is deeply studied based on the working principles of different combination modes. According to the performance analysis, the analytical expression of additional capacitance on the working mode is derived, and the optimal design scheme of additional capacitance parameters is put forward. Finally, in order to verify the effect of the additional capacitance C2 on the operation mode of the converter, an experimental analysis of the secondary parallel LCD forward converter which can avoid the reverse charging of the additional capacitor is carried out. The experimental waveform analysis verifies the correctness of the theoretical analysis and the feasibility of the design method of the additional capacitor parameters.

A Novel Pull-Up Active-Clamping Wireless Charging Circuit with Low Cost and Voltage Stress

The traditional single-switch circuit has the advantages of fewer components, no shoot-through problems, and suitability for high-frequency wireless charging applications. However, because of the high voltage stress of the switch, the bulky inductor, and the narrow soft-switching range, its power and applications have some limitations. To relieve this problem, this paper proposes a pull-up active-clamping circuit, which not only offers a low component count with no bulky inductors, but also greatly reduces the switch voltage stress. In addition, a wide range of soft switching can be achieved by designing a primary-side compensation capacitor. A detailed parametric design method is given and compared with existing circuits from the aspects of switch voltage stress, component count, efficiency, cost, and so on. Finally, a 1 MHz, 180 W active-clamping wireless charging system is built to verify the proposed circuit and design method.