Design Method Research Articles

A new method for synthesis and designing transmissive linear-to-circular polarization converters based on branch line circuit model

ABSTRACT This paper proposes a new design method of a linear-to-circular polarization converter based on the branch line circuit model. The series branches are implemented by dielectric spacers and the shunt branches are implemented by anisotropic admittance sheets. The admittance matrix of the anisotropic admittance sheets is derived by even and odd mode analysis. A unit cell consisting of two metal layers and a dielectric spacer is then designed using an iterative algorithm for operation from 15.5 to 23 GHz. Results indicate that the axial ratio and insertion loss of the designed polarizer are better than 3 and 1.5 dB respectively, for incident angles between ±45°. To validate the simulation results, a waveguide-based test setup is designed and fabricated, with measurement results indicating good agreement with simulations. The proposed method can be potentially applied to design other anisotropic structures such as half-plate polarizers and polarization rotators.

Equivalent continuous method based novel design of a nonlinear TMD with piecewise stiffness

Tuned mass Dampers (TMDs) are extensively used passive control devices for high-rise buildings to mitigate undesirable responses. In practice, limit devices are frequently applied due to the large displacement of TMD, resulting in the emergence of piecewise nonlinearity. In this study, a TMD with piecewise stiffness (PSTMD) is developed to investigate the piecewise nonlinearity, including piecewise linear stiffness (PLS) and piecewise nonlinear stiffness (PNS). Initially, a novel equivalent continuous method (ECM) is proposed based on the principles of the least squares method (LSM) to approximate the PSTMD using a nonlinear TMD with Duffing stiffness. The equivalent nonlinear TMD is proven to be accurate enough to approximate the PSTMD. Subsequently, frequency response analysis is conducted on the PSTMD designed by linear method, results indicate that the linear method fails to design PSTMD. Thirdly, the optimal parameters of PSTMD are determined based on the ECM and the improved design method for nonlinear TMD proposed by the author. Results indicate that this novel design method effectively enhances the performance of PSTMD and mitigates the effect of piecewise nonlinearity. Finally, the influence of parameters of PSTMD on the optimal tuning frequency is investigated. The influence of damping ratio of PSTMD is explored by numerical simulation, with results indicating that employing the damping ratio suggested by traditional linear design method as the optimal parameter is reasonable. In summary, the novel method proposed in this study holds significance for the engineering design of TMDs with piecewise characteristics.

Development of a wet digestion method for the analysis of metal soap in fat, oil, and grease deposits using the Taguchi method

Conventional methods for evaluating lipid-based metal salts in fats, oils and grease (FOG) deposits often fall short in assessing the efficiency of grease interceptors for food service establishment wastewater, primarily due to their inadequate specificity for fatty acid (FA) metal soaps. To address this issue, this study introduces a wet acid digestion method developed for the accurate analysis of metal soap content in FOG samples. The Taguchi experimental design method was used to determine the optimal conditions for digestion including temperature, contact time, solid/liquid ratio and type of acid mixture with the aim of more accurately quantifying metal salt concentrations. This work focused on identifying the most effective acid combinations for digesting FOG to enable analysis of commonly found metals. Extensive comparisons revealed that HNO3:H2SO4:H2O2 (1:2:1) and HNO3:H2O2 (1:3) were particularly effective at 180°C for 16h due to their significant oxidation potential. The HNO3:H2O2 (1:3) mixture yielded the highest concentrations of Ca, Mg, Na, and K of 296.38±0.66, 54.95±1.01, 247.65±2.27, and 46.09±3.44mg/g, respectively, aligning with the stringent optimisation principles of the Taguchi method. A one-way ANOVA test validated significant variances in metal contents (p < 0.005), and a t-test indicated a notably higher concentration of Ca compared to other metals. The study presents a sophisticated approach to evaluating the FA metal soap content of FOG ensuring enhanced accuracy and precision compared to established methods.

Research on foldable two-matrix 3D braided composites: Manufacturing and bending progressive damage

Research on foldable two-matrix 3D braided composites: Manufacturing and bending progressive damage

A Current-Stress-Optimized Design Method for Dual Active Bridge Converters With Improved ZVS Capability Under Wide Output Voltage Conditions

A Current-Stress-Optimized Design Method for Dual Active Bridge Converters With Improved ZVS Capability Under Wide Output Voltage Conditions

Improved deep learning based state of charge estimation of lithium ion battery for electrified transportation

The increasing interests and recent advancements in artificial intelligence and machine learning have significantly accelerated the development of novel techniques for the state estimation of batteries in the battery management systems (BMS) of electrified vehicles. To ensure the safe and reliable operation of an electric vehicle, it is essential to determine the state of charge (SOC) among the battery's numerous states. Deep learning models have been effective for SOC estimation due to the nonlinear and time-varying characteristics of a battery management system. This article seeks to describe an SOC estimator design method using deep neural network (DNN) models, particularly non-recurrent and recurrent neural networks, owing to their excellent computational intelligence and capacity for self-learning. A thorough investigation has been conducted at various temperatures, and the model is trained on data received from the cell during discharging processes like the urban dynamometer driving schedule (UDDS). Finally, the accuracy of the models is compared based on various performance indices. From the results, it has been concluded that the DNN models acquire a Mean Absolute Error (MAE) of less than 1 % and a Root Mean Square Error (RMSE) of close to 1 % when validated over various datasets at temperatures of 10 °C, 25 °C, and 40 °C.

Robust Design of 5th Generation District Heating and Cooling (5GDHC) Systems with Seasonal Thermal Energy Storage via GIS Assessment

This research addresses the need for a method to compare waste heat potential and recovery in 5th Generation District Heating and Cooling (5GDHC) systems. Prosumer buildings, known for enhancing flexibility, are analyzed using Geographic Information Systems (GIS) and image vectorization to evaluate 5GDHC systems. The study predicts the amount of waste heat available with an R2 of 0.96, utilizing Chaikin's algorithm to refine thermal images for automatic recognition of the sources of waste heat. Emphasis is placed on the absence of a method for asset design in 5GDHC, with considerations for annual energy calculations, radial network connections, and energy shares among building types. Recommendations for building connecting in Belgium are proposed, favoring 'B'/'C'-labeled buildings. The research explores the impact of building design on heating and suggests energy savings through regulation strategy changes. Dynamic models for heat pumps aim to reduce errors and emissions. The study connects energy indicators and GIS software, contributing to a top-down design approach in 5GDHC systems. The overall goal is to contribute to decarbonization and reduce CO2 emissions in the energy sector.

An improved IPT-PLL technology for single-phase grid-connected inverters in complex power grid conditions

Aiming at the common problems of frequency variations and harmonics in complex power grids, an improved inverse Park transform phase locked loop (IPT-PLL) technology for single-phase converters suitable for micro grid systems is proposed. Firstly, in the phase detection of PLL, the α component of Park transformation is selected as the reference voltage, and its orthogonal component is constructed using a 1/4 fundamental period delay method. Secondly, Lagrange interpolation polynomials are introduced to approximate fractional delay to solve the problem of delay calculation errors caused by frequency changes. Thirdly, in order to compensate for the poor ability of traditional proportional integral (PI) regulators, multi resonant controllers are superimposed to suppress low order harmonic disturbances. Finally, the design method and system performance of the PI regulator and each resonant controller are analyzed theoretically. The experimental results show that the proposed improved IPT-PLL method has strong adaptability to complex power grids. It can significantly improve the tracking performance of power grid frequency, suppress the interference of low order harmonics and DC bias. And it has good dynamic and static performance.

Pengaruh Penambahan Level Jus Tape Singkong Terhadap Kualitas Fisik Dan Kadar pH Silase Daun Tebu (Saccharum Officinarum L.)

This research aims to determine the potential of sugarcane leaf waste as animal feed and the addition of certain substances as starter bacteria, namely cassava tape juice which contains high levels of carbohydrates so that it can meet the nutritional needs of BAL during the fermentation period. The use of tape juice on the physical quality (aroma, color, texture) and pH levels of sugarcane leaf silage. This research is an experimental study using a completely randomized design (CRD) method consisting of 4 treatments and 5 replications. The treatments that will be applied are P0 (sugarcane leaves + 0% cassava tape juice), P1 (sugarcane leaves + 3% cassava tape juice), P2 (sugarcane leaves + 6% cassava tape juice), P3 (sugarcane leaves + cassava tape juice 9%), data analysis using Anova (Analysis of Variance) and if the data results are real, they are further tested with DMRT (Duncan Multiple Range Test). The research results showed that the addition of cassava tape juice did not improve the physical quality (aroma, color, texture) of silage and pH levels.

Backstepping synchronization control for four-dimensional chaotic system based on DNA strand displacement

Backstepping control is an important nonlinear control design method, which realizes the control of complex systems by constructing control law step by step, and has significant advantages for dealing with complex nonlinear systems. This article proposes a synchronization technique for four-dimensional chaotic systems using a combination of backstepping control method and DNA strand displacement technology. By relying on theoretical knowledge of DNA molecules, five basic chemical reaction modules such as trigger reaction, reference reaction, catalytic reaction, annihilation reaction and degradation reaction are given to construct a four-dimensional DNA chaotic system. On the basis of the relevant theory of chaotic dynamics, the constructed system is analyzed by Lyapunov exponent diagram and spectral entropy complexity algorithm, and the results come to the conclusion that the system reveals extremely complex and varied dynamic behaviors. Combining DNA strand displacement technology with backstepping control method, four controllers are developed to ensure that the trajectories of two homogeneous chaotic systems are synchronized. The numerical simulation results validate the feasibility and applicability of the proposed method. The method proposed in this paper may provide some references in the field of DNA molecular chaos synchronization control.

Sustainable Evaluation of E-Commerce Companies in Vietnam: A Multi-Criteria Decision-Making Framework Based on MCDM

This study aims to effectively support decision-makers in evaluating leading e-commerce companies in Vietnam from a sustainability perspective. In addition, this study evaluates and analyzes criteria that affect the performance of e-commerce companies in Vietnam to find the best practices for e-commerce implementation of managers. In this way, companies can save costs and increase marketing and promotion efficiency, helping to reach more customers. In doing so, an integrated framework based on MCDM is proposed for the first time in e-commerce industry assessment. In the first stage, the fuzzy decision making trial and evaluation Laboratory method is applied to determine the weights of 9 criteria based on collected data. This study lists prominent quantitative evaluation criteria, taking into account the sustainability aspect. In the second phase, ranking the top 12 e-commerce companies in Vietnam according to their performance based on these nine criteria was done by applying the neutrosophic fuzzy axiomatic design method. According to an analysis of the data, the external financial assistance coefficient (12.7%) is the most crucial factor determining how competitive international e-commerce businesses are. The results of this study can help underperforming companies make strategic decisions to improve their performance. Integrating these two techniques provides a new method for evaluating global trading companies that have hitherto remained unaddressed in the trading industry and, therefore, leave a gap that needs to be investigated.

Improvement of Traditional Energy-Saving Cold Alley Spaces: Case Study of Shixiangyuan Garden Renovation and Expansion Project in Guangzhou

Traditional cold alleys have the ability to adapt to hot climates with cooling and insulation, which is a traditional design method that conforms to sustainable development. Due to the limited depth of space and the adoption of mechanical ventilation in most contemporary architectural design, this passive energy-saving method is gradually being ignored. In this study, we use ventilation measurement and simulation to explore the characteristics of ventilation performance in the cold alleys of the renovation and expansion project of Shixiangyuan Garden. The research, using anemometers and thermometers for measurement, aims to explore how Shixiangyuan Garden can utilize its existing environment and improve it to adapt to local conditions, and also discusses the methods of increasing the number of air vents to improve the overall ventilation performance of the alleys, as well as the effects of form changes caused by utilizing water and plants to supplement the soft interface. Although many studies have explored the mechanisms of cold alleys in traditional architecture, few have discussed the variance of cold alley forms that could adapt to the limited depths of newly constructed buildings. This study attempts to explore the potential for this through simulation. The purpose is to find new ways to inherit the sustainable advantages of cold alleys in new projects.

Intercultural Communication as a Veritable Tool for Church Growth and Management in Lagos Metropolis

The reality of pluralism or multiculturalism of the church is evident from generation to generation since the inception of the church. In Lagos metropolis, the existence of diverse cultural and religious belief systems make intercultural communication a necessary skill for church growth and management. In view of this, the study investigated the level of awareness of intercultural communication and its relevance for church growth and management in Lagos metropolis. The framework for this study is premised on communication accommodation and cultural fusion theories. The study adopted a descriptive survey research design method while questionnaire was used as the instrument to gather relevant data from two hundred and ten respondents (210) selected amongst leaders and members of Baptist churches in Lagos metropolis. Baptist is one of the dominant denominations in Lagos. The study discovered that there is a high level of awareness of intercultural communication skill among members and leaders of the selected churches, but there is the challenge of language and cultural superiority among the respondents. This is capable of hindering church growth and management. Therefore, the study recommends that language and cultural superiority should be prevented in the church. More so, the church leaders and members need to undergo constant training on intercultural communication skills. The church needs to create intercultural functional management and administrative structure for equity and oneness among people of diverse cultures in the church.

A decoupled probabilistic constrained topology optimization method based on the constraint shift

AbstractTopology optimization (TO) has recently emerged as an advanced design method. To ensure practical reliability in the design process, it is imperative to incorporate considerations of uncertainty. Consequently, performing reliability analysis (RA) during the design phase becomes necessary. However, RA itself constitutes an optimization problem. Combining these two optimization problems can result in inefficiency. To address this challenge, we propose a decoupled approach that integrates deterministic topology optimization (DTO) and RA cycles. The reliability‐based stress‐constrained TO (RBSCTO) problem is considered in this paper. The DTO constraint is derived based on shifting vectors derived from the previous cycle's RA outcomes, enabling low‐reliability constraint shift towards the feasible direction. The DTO is solved based on solid‐isotropic‐material‐with‐penalization (SIMP) and augmented Lagrangian method. Meanwhile, the optimization problem in RA is addressed using finite differences and the interior point method. To reduce the errors resulting from linear approximation and optimization in RA when the target reliability is very low, an outlier handling method is employed. Meantime, we utilize a probabilistic neural network to enhance the efficiency of reliability assessment. Comparative studies against traditional methods across four RBSCTO tasks are demonstrated to validate its effectiveness. Monte Carlo simulations are used to validate the reliability of results.

AK-MADDPG-Based Antijamming Strategy Design Method for Frequency Agile Radar

AK-MADDPG-Based Antijamming Strategy Design Method for Frequency Agile Radar

A multi-objective optimization design method for underwater composite sandwich structures with high acoustic transmission and low vibration performance

ABSTRACT To address the issue of reduced structural integrity and optimality resulting from the conventional serial design of sonar dome structures, this paper establishes a multi-objective optimal design model for composite sandwich structures, utilising the Non-dominated Sorting Genetic Algorithm-II (NSGA-II). The model's stability and reliability are subsequently validated. Upon this model, a structural optimization design technique is postulated for composite sandwich structures within the realm of Fluid-Structure Interaction (FSI) multi-physics coupling. This approach aims to optimize the lightweight, high-rigidity composite sandwich structure, enhancing its acoustic transmission and minimizing vibration performance under turbulent pressure pulsations. The suggested method notably enhances the efficiency of structural design while ensuring precision. The proposed method effectively addresses the deficiency of serially designed sonar domes by neglecting the synergistic effects among multiple disciplines. In summary, this approach offers technical support and new research perspectives for the design of sonar domes under the coupling of multiple physical fields.

Design method and seismic vulnerability of bridges using UHPC-NSC composite pier

The focus of this investigation is the application of ultra-high-performance concrete (UHPC) and normal strength concrete (NSC) in constructing composite piers. The UHPC-NSC composite pier, comprising the external UHPC jacket and internal NSC, demonstrates a marked enhancement in both load-bearing capacity and control of seismic damage. However, the lack of suitable seismic design methodologies presents a significant barrier to the practical application of the composite pier. Drawing on extensive experimental and theoretical research, this paper proposes an optimization formula that determines the diameter of the composite pier and the thickness of the UHPC jacket. This formula aims to maximize the use of UHPC material, manage the damage, and equalize sectional moment resistance with the original reinforced concrete section. Utilizing the proposed design approach, UHPC-NSC composite piers were implemented in a typical continuous beam bridge. Seismic vulnerability analyses were conducted to quantitatively substantiate the performance of the composite pier following the aforementioned design approach. The analysis affirmed that the composite pier effectively reduced the exceeding probability of all damage levels under small and moderate earthquakes, and extensive damage level under strong earthquakes.

Tornado-induced instability assessment of super large hyperbolic reinforced concrete cooling towers

Cooling towers are typical high-rise thin-walled structures which are of hyperbolic rotating shell structure type and significantly sensitive to wind loads. Wind-related local instability is the key control factor in the design of structural geometric shape and tower shell thickness optimization. In fact, this kind of stability analysis has only conducted aiming at normal climate (such as monsoon, etc.) under the guideline of series of national Codes. In order to deal with the issues under disaster climate, physical and numerical investigation to evaluate local stability performance of a super large cooling tower (SLCT) under tornado environments based on Buckling Stress State (BSS) method is implemented. Besides, whole process elastic–plastic collapse simulation of the SLCT exposed to the tornados was also carried out to study the failure mechanism and re-evaluated the reasonability of the well-accepted BSS method for structural wind-resistant design. The results revealed that the tornados would have obvious adverse effects on the structural local stability when the SLCT is located at the tornado vortex core radius compared with those under traditional synoptic winds. The swirl ratios and the central distances between the SLCT and the tornado vortex core have significant effects on the local instability of the SLCT. The extended elastic–plastic collapse simulation discovered that the position of the first crack during SLCT collapse process is basically consistent with the critical position from the elastic local stability analysis of the SLCT, indicating that strengthening measures can be carried out in advance at the critical position for structural local stability improvement under tornado conditions. Besides, the extended elastic–plastic collapse numerical simulation of the SLCT could be as the effective supplement to the structural elastic stability assessment (such as BSS method) in the wind-resistant design of the SLCT.

A mechanically robust and facile shape morphing using tensile-induced buckling.

Inspired by the adaptive mechanisms observed in biological organisms, shape-morphing soft structures have emerged as promising platforms for many applications. In this study, we present a shape-morphing strategy to overcome existing limitations of the intricate fabrication process and the lack of mechanical robustness against mechanical perturbations. Our method uses tensile-induced buckling, achieved by attaching restraining strips to a stretchable substrate. When the substrate is stretched, the stiffness mismatch between the restraining strips and the substrate, and the Poisson's effect on the substrate cause the restraining strips to buckle, thereby transforming initially flat shapes into intricate three-dimensional (3D) configurations. Guided by an inverse design method, we demonstrate the capability to achieve complicated and diverse 3D shapes. Leveraging shape morphing, we further develop soft grippers exhibiting outstanding universality, high grasping efficiencies, and exceptional durability. Our proposed shape-morphing strategy is scalable and material-independent, holding notable potential for applications in soft robotics, haptics, and biomedical devices.

A novel design algorithm for low complexity sparse 2‐D FIR filters

SummaryThe hardware implementation complexity of traditional two‐dimensional (2‐D) finite impulse response (FIR) filters with high order is very high. In this paper, a novel sparse 2‐D FIR filter design algorithm has been proposed by combining the common subexpression elimination technique and sparse filter design algorithms to reduce hardware implementation complexity. First, an initial 2‐D FIR filter with sparse coefficients that meets frequency‐domain specifications is obtained by the sparse filter design algorithm. Then, each filter coefficient is quantized in canonical signed digit, and the sensitivities of all weight‐two subexpressions and isolated non‐zero bits are calculated. Finally, the filter coefficients with low implementation cost are reconstructed via iteratively choosing subexpressions and isolated non‐zero bits in terms of their sensitivities. Simulation results show that the proposed algorithm saves about of adders compared with other low complexity filter design method, which reduces effectively the implementation cost.