Design Parameters Research Articles

Distributed deadband event-triggered observer-based containment control for unmanned surface vehicles with channel fading

This article investigates the distributed deadband event-triggered containment control problem for multiple underactuated surface vehicles (USV) systems whose communication networks are subject to channel fading. The first distributed deadband event-triggered observer (DDETO) was proposed to observe the target positions of the followers in the convex hulls formed by the leaders. It also manages the internal communication between the followers in the presence of channel fading. In addition, the deadband event-triggered mechanism (DETM) in DDETO guarantees a strictly positive minimum inter-event times (MIET), which can be accurately calculated and adjusted according to the design parameters. Afterward, an adaptive controller is designed by backstepping based on the desired position information observed by DDETO. It is worth noting that the containment control scheme proposed in this paper is based on relative position measurement only, which reduces the amount of information transfer compared to transmitting position and velocity information when wireless signals are fading in the channel, improves the control accuracy, and also reduces the system’s requirements for sensors. Theoretical analysis leads to the conclusion that the error signals are uniformly ultimately bounded (UUB). Finally, the effectiveness of the control scheme is verified by numerical simulation.

Realizing In-Memory Computing using Reliable Differential 8T SRAM for Improved Latency

Traditional von Neumann computing architectures suffer from high energy and lower speed as compared to the requirements of modern applications like those required in neural network accelerators. A modified differential eight transistor (8 + T) static random access memory (SRAM) based in-memory computing (IMC) structure was presented for realizing bit-wise boolean logic operations. The 8 + T SRAM-IMC is designed at 32 nm technology node with throughput of 2.1849, 2.4815, 2.5795, 2.6240, 2.6495, 2.6619, 2.6690, 2.6732 and 2.6749 giga outputs per second (GOPS) for 0.5-1.3 V supply voltage range respectively. The differential 8T cell used to implement logic operations supports NAND and NOR operations with minimal overhead while also performing the standard storage operation with added stability over the conventional 6T and 8T SRAM cells. The SRAM-IMC offers reliable boolean logic operations by using asymmetric sensing strategy for all process corners, TT, SS, SF, FS and FF for an operating temperature range of 220 K to 400 K. Monte carlo simulation considering global threshold voltage deviation of 50 mV were performed for various operating condition in order to study the impact of variations on design parameters such as latency.

Design Parameters Affecting Rill Swell Events for Block Caving Applications

Rill swell (RS) events are outflows of dry, fine-grained material mainly observed at drawpoints in cave mining. These events can negatively affect production and have fatal consequences. Unfortunately, comprehensive studies analyzing these events are lacking. This paper uses the discrete element method to study RS events. With this method, a numerical model was constructed and calibrated based on an RS event recorded in Ridgeway Deeps Block Cave. Drawpoint geometries, material properties, and the initial mass of the fine material were then analyzed. The results show that both the brow beam height and drawpoint width had a noticeable influence on the RS magnitude, mainly on the tonnage of the flow and the distance reached by coarse particles dragged into the extraction drift. While the mass of fine material is crucial to the magnitude of RS events, results suggest that narrowing drawpoint width and/or increasing brow beam height can mitigate the impact of RS events.

Quality of life: quantitative analysis in New Urbanism and LEED-ND certified neighbourhoods

Given the substantial rise in the urban population, it is imperative to evaluate the quality of life (QoL) in residential communities. New Urbanism (NU) and Leadership in Energy and Environmental Design for Neighborhood Development (LEED-ND) are globally recognised neighbourhood design initiatives that strive to improve QoL. Nevertheless, the degree to which these initiatives effectively enhance QoL remains questionable. This assessment seeks to evaluate the effectiveness of key design practices in these two initiatives by examining the satisfaction levels of residents. It focuses on five key attributes that contribute to enhancing the QoL in residential neighbourhoods: safety, comfort, connectivity, sense of place, and aesthetic appeal. Three neighbourhoods were selected for analysis in the USA. The residents’ questionnaire was utilised as the main tool for the quantitative analysis. The findings revealed a positive association between safety and comfort and overall QoL. NU neighbourhoods showed the highest satisfaction levels, while LEED-ND neighbourhoods had the lowest. Key determinants of QoL were identified as well. The main contribution of this study is to provide insights for enhancing the design parameters of NU and LEED-ND certification to improve QoL and bridge the gap between professionals’ perspectives and residents’ preferences.

Seismic Design and Ductility Evaluation of Thin-Walled Stiffened Steel Square Box Columns

This paper investigates the seismic performance of thin-walled stiffened steel square box columns, modeling bridge piers subjected to unidirectional cyclic lateral loading with a constant axial load, focusing on local, global, and local-global interactive buckling phenomena. Initially, the finite element model was validated against existing experimental results. The study further explored the degradation in strength and ductility of both thin-walled and compact columns under cyclic loading. Thin-walled, stiffened steel square box columns exhibited buckling near the base, forming a half-sine wave shape. The research also addresses discrepancies from different material models used to analyze steel tubular bridge piers. Analysis using a modified two-surface plasticity model (2SM) yielded results closer to experimental data than a multi-linear kinematic hardening model, particularly for compact sections. The 2SM, which accounts for cycling within the yield plateau and strain hardening regime, demonstrated enhanced accuracy over the multi-linear kinematic hardening model. Additionally, a parametric study was conducted to assess the impact of key design parameters—such as width-to-thickness ratio (Rf), column slenderness ratio (λ), and magnitude of axial load (P/Py)—on the performance of thin-walled stiffened steel square box columns. Design equations were then developed to predict the strength and ductility of bridge piers. These equations closely matched experimental results, achieving an accuracy of 95% for ultimate strength and 97% for ductility.

3D Printed Microneedles for the Transdermal Delivery of NAD+ Precursor: Toward Personalization of Skin Delivery.

3D printing of microneedles (μNDs) for transdermal therapy has the potential to enable patient personalization based on the target disease, site of application, and dosage requirements. To convert this concept to reality, it is necessary that the 3D printing technology can deliver high resolution, an affordable cost, and large print volumes. With the introduction of benchtop 4K and 8K 3D printers, it is now possible to manufacture medical devices like μNDs at sufficient resolution and low cost. In this research, we systematically optimized the 3D printing design parameters such as resin viscosity, print angle, layer height, and curing time to generate customizable μNDs. We have also developed an innovative 3D coating microtank device to optimize the coating method. We have applied this to the development of novel μNDs to deliver an established NAD+ precursor molecule, nicotinamide mononucleotide (NMN). A methacrylate-based polymer photoresin (eSun resin) was diluted with methanol to adjust the resin viscosity. The 3D print layer height of 25 μm yielded a smooth surface, thus reducing edge-ridge mismatches. Printing μNDs at 90° to the print platform yielded 84.28 ± 2.158% (n = 5) of the input height thus increasing the tip sharpness (48.52 ± 10.43 μm, n = 5). The formulation containing fluorescein (model molecule), sucrose (viscosity modifier), and Tween-20 (surface tension modifier) was coated on the μNDs using the custom designed microtank setup, and the amount deposited was determined fluorescently. The dye-coated μND arrays inserted into human skin (in vitro) showed a fluorescence signal at a depth of 150 μm (n = 3) into the skin. After optimization of the 3D printing parameters and coating protocol using fluorescein, NMN was coated onto the μNDs, and its diffusion was assessed in full-thickness human skin in vitro using a Franz diffusion setup. Approximately 189 ± 34.5 μg (5× dipped coated μNDs) of NMN permeated through the skin and 41.2 ± 7.53 μg was left in the skin after 24 h. Multiphoton microscopy imaging of NMN-coated μND treated mouse ear skin ex vivo demonstrated significantly (p < 0.05) increased free-unbound NADPH and reduced fluorescence lifetime of NADPH, both of which are indicative of cellular metabolic rates. Our study demonstrates that low-cost benchtop 3D printers can be used to print high-fidelity μNDs with the ability to rapidly coat and release NMN which consequently caused changes in intracellular NAD+ levels.

Multi‐parameter design optimization of crash box for crashworthiness analysis

AbstractThis study focuses on the optimization process of crash box design. The design optimization process is resource‐intensive and requires multiple dynamic simulations. Numerous design parameters can be varied to satisfy the crashworthiness objectives. Therefore an intelligent and robust machine learning (ML) framework has been developed. This framework can be employed to assist in the optimization of various crashworthiness components with different crashworthiness objectives.Here, a reinforcement learning‐based (RL) machine learning framework is developed. It consists of a finite element method (FEM) surrogate and RL environment. The FEM surrogate is trained using data from FEM simulations as well as synthetic data generated by a Generative Adversarial Network (GAN). An inverse problem is solved for optimizing the geometrical parameters of the boundary value problem while the RL is receiving input from the FEM surrogate. RL has proven to be accurate in many fields due to its ability to explore and exploit the learned dynamics. Conventional algorithms require numerous iterations and tuned functions to achieve appropriate results and need to be initialized after a slight change in the problem. Due to an optimization of input parameters in an inverse problem, RL is chosen for the present investigation.For the simulation data needed, the crash box is designed with linear first‐order accurate four nodal shell elements. Also, bilinear elastoplastic material along with geometrical nonlinearity is used to simulate the dynamic deformation process.The RL agents learn to vary the crash box design parameters and search for the optimal parameters. The optimal parameters are based on the user‐defined crashworthiness objectives.

Centrifuge tests for earthquake response of shallow soil with locally raised bedrock

ABSTRACT Centrifuge tests were performed to study the dynamic properties of shallow soil with locally raised bedrock (i.e. variable soil depth). The test parameter was the slope of bedrock: 0° (S0), 35° (S35), and 45° (S45). In each test, accelerations were measured along the soil depth, and the results of acceleration, displacement, Fourier transform, and response spectrum were compared. Based on the results, the transfer function (TF), the ratio of response spectrum (RRS), and the site period were estimated. The ground motion and site period of specimens with raised bedrock were smaller than those of the specimen without raised bedrock (i.e. with deeper soil). Further, parametric studies using 2-dimensional finite element (FE) analysis were performed to investigate the effect of design parameters on the response of shallow soil with variable soil depths. For design parameters, the length of raised bedrock and the length of foundation slab were considered. Parametric study results indicated that when the shallow soil region is wide, the results are similar to those of a 1-dimensional soil column. However, when the shallow soil region is narrow, the 2-dimensional response is smaller than the 1-dimensional soil column response. This was also observed in the actual site model.

Multi-objective optimization and comprehensive Thermodynamic, economic, and environmental analysis of an innovative solar-geothermal integrated system for synergistic power generation and water desalination

ABSTRACT This paper presents a novel multi-objective optimization and sustainability analysis framework for an innovative solar-geothermal integrated system for power generation and water desalination. Harnessing renewable solar and geothermal energy, the system offers a sustainable solution for energy, water, and environmental challenges. Advanced thermodynamic modeling techniques, validated by industry simulations, accurately characterize system performance. Departing from conventional analyses, the research incorporates exergy-based economic and environmental assessments and the emergy concept to quantify the total available energy required, enabling a comprehensive sustainability evaluation. Through multi-objective optimization using genetic algorithms, the system’s design and operational parameters are optimized to enhance exergy efficiency, economic emergy performance, and environmental emergy performance simultaneously. The optimization framework considers turbine inlet conditions, pressures, and desalination configurations to identify optimal operating points balancing energy efficiency, economic feasibility, and environmental impact. Results demonstrate significant improvements of up to 23.49% in exergy efficiency, 25.97% in economic emergy performance, and 16.04% in environmental emergy performance compared to the baseline system. This study focuses on the multi-objective optimization of a novel solar-geothermal integrated system for synergistic power generation and water desalination. The methodology combines thermodynamic, economic, and environmental analyses to evaluate system performance. Key findings include a significant improvement in overall efficiency and sustainability compared to conventional systems, highlighting the potential for large-scale implementation.

Experimental validation of an efficient strategy for FE model updating and damage identification in tubular structures

ABSTRACT Early identification of damages in tubular structures is crucial for their long-term safety and functionality, as they are essential in various modern life applications. Experimental and numerical modal data may slightly differ due to unknown structural characteristics and uncertainties, which are typically addressed using finite element (FE) model updating procedures. Instead of using the Euler-Bernoulli beam element, this paper utilises the semi-rigidly connected frame element (S-RCFE). By incorporating extra design parameters, such as the end fixity factor of all connections, the S-RCFE offers a unique opportunity to establish a strong agreement between experimental and numerical models through an optimisation-based FE model updating procedure. A well-calibrated FE model represents the actual behaviour of the structure and leads to achieving accurate results in the damage detection step. This paper employs the improved grey wolf optimiser (IGWO) and weIghted meaN oF vectOrs (INFO) to minimise 11 objective functions with adjustable coefficients. The statistical investigations reveal that the IGWO effectively minimised five out of six objective functions, which were defined based on the modified total modal assurance criterion (MTMAC). The rest of the objective functions based on the modal assurance criterion (MAC), natural frequency vector assurance criterion (NFVAC), differences in natural frequencies, and a combination of the MAC and NFVAC could not obtain accurate outcomes for the model updating problem. The statistical comparison indicates that the INFO algorithm is unreliable for the FE model updating despite achieving at least one successful result in ten independent runs. The INFO algorithm and the IGWO algorithm demonstrate comparable performance in damage detection. The analysis also shows that the coefficients of MTMAC, alpha and beta, should be adjusted to 0.65 and 1, respectively, to achieve the most accurate damage detection result.

Design and demonstration of a roll-out membrane antenna based on thin-walled deployable composite booms

The thin-walled deployable composite boom (DCB) features the advantages of high deployment-to-package envelope ratio and elastic self-development, which is an enduring topic of interest in the field of lightweight aerospace structures. The structural design and performance demonstration was proposed herein for a roll-out membrane antenna (ROMA) based on DCBs. Firstly, a simplified analytical algorithm was formulated for approximate fundamental frequencies of the ROMA frame structure, and the two types of first-order torsional modal shapes of the frame structure was investigated with respect to configurational design parameters. In sequentially, the bending, swing and the two distinct torsional fundamental frequencies of the ROMA frame were estimated comparatively. Furthermore, the effects of the equilibrated tension from the membrane array on the bending fundamental frequency of the ROMA structure was investigated by assuming a simplified mass distribution model for the thin-film structures. Finally, The simplified analytical algorithm was used for structural design of an AIS/VDE (automatic identification system/VHF data exchange system) ROMA and its performance was validated through numerical simulations and ground tests. The successful deployment and operation of the AIS/VDE ROMA on the Pujiang-2 satellite further demonstrated the practical aerospace application significance of thin-walled DCBs.

A novel heat recovery VRF system: Principle and cooling performance analysis

Faced with an increasingly severe energy problem and increased demand for indoor comfort, heat recovery VRF systems have demonstrated remarkable potential for energy conservation. However, traditional heat recovery VRF systems need more suboptimal energy efficiency in terms of cooling and dehumidification and fail to guarantee precise temperature and humidity control in specific environments. In this study, a novel heat recovery VRF system that can achieve highly efficient cooling while ensuring precise humidity control is proposed. It can realize four primary operation modes by changing the function of indoor heat exchangers. The results showed that the optimal volume ratio of the two compressor cylinders was 1.4, which was used as the design parameter for the system. Compared to the single-evaporation temperature system, the proposed double-evaporation temperature system has better energy efficiency and dehumidification capacity in the cooling mode. The cooling coefficient of performance (COP) can be increased by 3.18 %–6.05 %, the compressor energy consumption can be reduced by 3.07 %–7.03 %, and the moisture extraction rate and latent heat ratio of the system can be increased by 5.6 %–33.3 %.

Analysis of synergistic influence of multi-scale design parameters on nearly-zero energy office blocks performance based on architectural morphological classification and parametric modeling

Analysis of synergistic influence of multi-scale design parameters on nearly-zero energy office blocks performance based on architectural morphological classification and parametric modeling

Thermal performance optimization for a tapered heat sink of bus bar conductor using definitive screening design

This study examines and optimizes four design parameters of a bus duct conductor's heat sink: fin pitch, fin height, fin thickness, and the number of fin valleys. Average surface temperature and Nusselt number are chosen as the thermal performance criterion of the heat sink. A Definitive Screening Design is employed as a statistical method to reduce the number of optimization runs required while minimizing the aliasing. The regression analysis, analysis of variance, main effect analysis and optimization are conducted to optimize the heat sink design parameter and its thermal performance. The current results provide an ideal heat sink design for the casing of bus duct conductors. A fin pitch of 4 mm, fin height of 6.5 mm, fin thickness of 1 mm, and six fin valleys are determined to be the most optimal combination of design parameters. The optimized responses' average surface temperature and Nusselt numbers are 72.05 °C and 21.59, respectively, with 2.97 % and 6.25 % deviation from the predicted values of the empirical equation. The experimental results are benchmarked against the IEC 60439-1 and IEC 60439-2 standards. The current analysis is expected to provide more insight into the impact of design factors on the thermal performance of a bus duct conductor.

A novel negative Poisson’s ratio structure with high Poisson’s ratio and high compression resistance and its application in magnetostrictive sensors

Currently, dead zones and low sensitivity have hindered the utilization of magnetostrictive sensors. In this paper, a new negative Poisson’s ratio structure inspired by an hourglass is proposed to provide a feasible idea for this problem. The novel negative Poisson’s ratio structure exhibits a high Poisson’s ratio and a high compression resistance. Theoretical studies have demonstrated that the structure’s performance is strongly dependent on four design parameters. The structure is analyzed and tested via finite element analysis simulation by changing the design parameters. This structure’s negative Poisson’s ratio can reach up to −1.004. It possesses a compressive strength of 1.83 kN and an energy absorption capacity of 8.72 J. A magnetostrictive sensor using the proposed negative Poisson’s ratio structure as the base realizes a 271.7 % sensitivity improvement. The problem of dead zones in magnetostrictive sensors can be also solved simultaneously. The proposed structure in this paper provides a feasible solution for further expanding the applications of magnetostrictive sensors.

CFD Simulation of Pre-Chamber Spark-Ignition Engines—A Perspective Review

The growing demand to reduce emissions of pollutants and CO2 from internal combustion engines has led to a critical need for the development of ultra-lean burn engines that can maintain combustion stability while mitigating the risk of knock. One of the most effective techniques is the pre-chamber spark-ignition (PCSI) system, where the primary combustion within the cylinder is initiated by high-energy reactive gas jets generated by pilot combustion in the pre-chamber. Due to the complex physical and chemical processes involved in PCSI systems, performing 3D CFD simulations is crucial for in-depth analysis and achieving optimal design parameters. Moreover, combining a detailed CFDs model with a calibrated 0D/1D model is expected to provide a wealth of new insights that are difficult to gather through experimental methods alone, making it an indispensable tool for improving the understanding and optimization of these advanced engine systems. In this context, numerous previous studies have utilized CFD models to optimize key design parameters, including the geometric configuration of the pre-chamber, and to study combustion characteristics under various operating conditions in PCSI engines. Recent studies indicate that several advanced models designed for conventional spark-ignition (SI) engines may not accurately predict performance under the demanding conditions of Turbulent Jet Ignition (TJI) systems, particularly when operating in lean mixtures and environments with strong turbulence–chemistry interactions. This review highlights the pivotal role of Computational Fluid Dynamics (CFDs) in optimizing the design of pre-chamber spark-ignition (PCSI) engines. It explores key case studies and examines both the advantages and challenges of utilizing CFDs, not only as a predictive tool but also as a critical component in the design process for improving PCSI engine performance.

A vibro-impact remote-controlled capsule in millimeter scale: Design, modeling, experimental validation and dynamic response

This paper represents a new solution to the design problem of integrating sufficient power source, actuator, and controller into a "pill-sized" form of a typical capsule. All components are enclosed in an 11 mm diameter, 36 mm long cylinder weighing 7.26 gs. The actuator was designed so that a battery with a capacity of 35 mAh can theoretically supply sufficient energy for 7 h of operation. The excitation's amplitude, frequency, and duty cycle are remotely controlled by a wireless pulse width modulation signal. All steps of the new system development are fully described, including conceptual and embodiment design, fabrication, experimental setup, and parameter identification. The mathematical model is then experimentally validated and used to analyze the system response, where the bifurcation technique is applied to carry out the coexisting attractions and their basins. Recommendations on design and operational parameters are then provided, considering progression and energy efficiencies. The results provide the feasibility of further studies to realize vibro-impact driven and remote-controlled capsules using wireless control in standard size.

Enhanced biosensing with rhombic ring resonator in 2D photonic crystals for proteinuria detection

A two-dimensional (2D) photonic crystal (PC) based biosensor was developed and studied to detect albumin and urea levels in patients with proteinuria. Rhombic ring resonator structures are built with the help of FDTD (Finite Difference Time Domain). After the fields are computed using the 2D-FDTD approach, the normalized transmission spectra are produced by applying the Fast Fourier Transform (FFT) to them. The full width at half maximum (FWHM), Quality factor (Q-factor), Sensitivity, Figure of Merit (FOM), and Limit of Detection (LOD) are 15,466.5, 110 nm/RIU, 0.12 nm, 1100 RIU−1 and 54.34X10−6 RIU respectively, when the resonant wavelength is 1546 nm. The novelty of this the project lies in combining 2D photonic crystal, innovative rhombic ring resonator design and high-performance parameters. The achieved values are notably high, which is a novel achievement in the field of biosensing. The project aims to contribute to the field of biosensors and provide a potential tool for healthcare professionals to monitor diabetes, proteinuria, kidney function and overall health.

Influence of design parameters on heat production of a multilateral butted closed loop geothermal system

To efficiently develop hot dry rock and other geothermal energy, a multilateral butted closed loop geothermal system (MBCLGS) is presented in this paper to replace the U-shaped closed-loop geothermal system (UCLGS). Besides, a casing-cement-formation transient heat transfer model is established to investigate the influences of key factors on the heat production of MBCLGS. After thermal-fluid-structural coupling analysis, we can find that higher injected rate and lower fluid temperature can improve heat power but reduce output temperature. In addition, the output temperature and heat power do not increase continuously with the increasing of branch well number. There is an optimal value of branch well number. Longer well pair distance can improve both output temperature and heat power. Considering the drilling technology level and design purpose, the recommended injected flow rate of MBCLGS is 90 m3/h, the injected fluid temperature is 42.5 °C, the number of branch wells is 10 and the well pair distance is 200m. Finally, by comparing MBCLGS and UCLGS, it is found that MBCLGS has a lower temperature decline rate and higher output temperature than UCLGS under the same conditions. It works more stable and has better economy. Overall, the proposal of MBCLGS is expected to promote the efficient development of deep geothermal resources.

The study of design and optimisation for CFRP combined pier anti-collision device

A CFRP honeycomb combination anti-collision device with a larger anti-collision level, greater crashworthiness, and longer service life was designed to safeguard the ship and piers in the event of an unintentional collision. Taking large-tonnage cargo ships and common bridge piers in the middle reaches of the Yangtze River as the research objects, the energy conversion response, impact force response and impact depth response of the collision were studied considering the collision conditions between the ship and the bare pier and the collision avoidance device. On this basis, the response surface method, variance analysis method and efficacy coefficient method were further used to take the shell thickness of the collision avoidance device and the thickness of the internal steel structure as the design parameters. The multi-objective optimisation design of the CFRP composite anti-collision device is carried out by selecting the ship impact force, the total internal energy absorbed by the anti-collision device, the total mass, and the inner diameter of the honeycomb steel structure as the optimisation objectives. The results show that the impact force reduction rate reaches 82.7%, the overall mass is greatly reduced, the maximum deformation is within a reasonable range, and the collision resistance is optimised.