Parametric Design Research Articles

Dynamic quantization‐driven stability of networked control systems under DoS attacks

AbstractThis paper focuses on the stability problem of networked control systems (NCSs) under denial‐of‐service (DoS) attacks and bandwidth limitation. Firstly, the periodic dynamic quantization mechanism is extended to insecure systems, and a periodic‐like quantization strategy is proposed. Due to the designable period, such mechanism allows a trade‐off between better system performance and less energy consumption. With finite quantization levels, a reasonable parametric design is given to avoid quantizer saturation under general energy‐constrained DoS attacks. Secondly, a suitable quantized controller is designed for the system affected by DoS attacks. The relationship between the quantized controller and the DoS attacks is analyzed, and the criterion for NCSs achieving global asymptotic stability is derived. Finally, two numerical examples are given to verify the correctness of the theoretical result.

Effects of Subsurface Pipe Drainage Spacing on Soil Salinity Movement in Jiangsu Coastal Reclamation Area

The agricultural development of reclaimed coastal areas in Jiangsu Province is significantly hindered by high soil salinity and an inadequate irrigation and drainage infrastructure. Optimizing the layout of subsurface drainage systems has been identified as an effective means of reducing soil salinity, with the proper designation of engineering parameters being crucial. This study applied 12 treatments (T1–T12) consisting of four different spacings of subsurface drainage pipes (6 m, 11 m, 15 m, and no subsurface drainage pipes) and three observation wells at varying distances from the drainage outlet (5 m, 25 m, and 45 m). Results showed that all three subsurface pipe spacing treatments significantly reduced soil salinity compared to natural drainage, with a smaller subsurface pipe spacing treatment leading to better salt-reducing effects. The farther the distance from the measuring point to the drain, the higher the salinity. As the burial depth of the outlet decreased and spacing between the subsurface drainage pipes decreased, the salinization rate of the 0–60 cm soil layer was higher, while the salt accumulation in the 60–80 cm soil layer was more severe. Therefore, a subsurface drainage pipe spacing of 6 m and an outlet burial depth of 40 cm are recommended as more suitable choices to effectively control salt concentration in the soil. The research aimed to provide scientific reference data and technical support for the optimized design of subsurface drainage engineering parameters while promoting efficient desalination of saline-alkali areas worldwide.

Optimization design and parametric research of belt conveyor deck truss structure

A belt conveyor deck truss (truss for short) is an important component of a belt conveyor, which has the functions of bearing and supporting. In this paper, a meta-heuristic optimization algorithm was employed to replace traditional finite element optimization to achieve a lightweight design and avoid the high consumables and low-efficiency problems due to conservative design. Therefore, it was proven that the applicability and stability of this algorithm were better than other algorithms. Then, the response surface and sensitivity analyses were carried out to directly show the relationship between the design variable and the objective function. Finally, the optimized truss rods profiles were saved in the database, and the classes in the Application Programming Interface (API) provided by Tekla Structures were instantiated to achieve the parametric modeling and drawing of the truss. The results showed that the optimization efficiency was greatly improved through the Harris hawks optimization method, and the mass of the optimized truss was reduced by 19.21%. The efficiency of the truss modeling and drawing, the flexibility of design were improved through the parametric design combined with Tekla Structures. This study provided practical guidance for parametric research and lightweight truss design, which possessed promising engineering application value.

Parametric design and energy absorption of non-uniform classic honeycombs mapped by topology optimization

In this article, a non-uniform design method mapped by density-based topology optimization is proposed and applied to the classic hexagonal honeycombs. A parametric investigation is conducted to explore the effect of crucial factors on the in-plane and out-of-plane crashing behaviors and energy absorption of the non-uniform honeycomb mapped by topology optimization. Compared to classic hexagonal honeycombs, the in-plane specific energy absorption of the non-uniform honeycomb mapped by topology optimization is improved by 29.1%, and its peak stress is decreased by 16.9%. Meanwhile, the out-of-plane specific energy absorption is increased by 19.8% without a significant rise in peak stress.

Optimizing Sustainable Suburban Expansion with Autonomous Mobility through a Parametric Design Framework

Optimizing Sustainable Suburban Expansion with Autonomous Mobility through a Parametric Design Framework

Generative design of terraced concert hall – a case study of Taipei music and library centre

ABSTRACT The terraced concert hall offers a wide range of design options. Yet the knowledge barrier within a design team makes it difficult to effectively deliver a design that satisfies both the needs of creativity and acoustics. The study aims to explore the integration of generative parametric design collaboration workflow into the design of terraced concert halls and apply the cumulative results of the pilot study to the Taipei Music and Library Centre design competition. We propose an enhanced collaborating model between architects and acoustic consultants, integrating geometric design with acoustic verification in concert hall design. This cooperating model embraces and integrates three key steps: defining basic parameters and reference geometries, efficiently generating and composing geometric elements, and conducting geometric and acoustic statistical assessments. This design strategy enables integration of diverse viewpoints, covering both the acoustics within the hall and the space integration with the surroundings. The outcome is a terraced concert hall with an acoustic performance comparable to traditional shoebox-shaped halls.

A Neural Network Approach to Estimate the Frequency of a Cantilever Beam with Random Multiple Damages.

Natural frequency is an important parameter in the structural health monitoring (SHM) system. Any changes in this parameter indicate structural alteration due to damage. This study provides a neural network (NN) solution as an alternative to the finite element (FE) method to measure the natural frequencies of a cantilever beam with random multiple damage. It is based on a statistical dataset of a free vibration test obtained from the APDL (Ansys parametric design language) simulation using a MATLAB (matrix laboratory) script. The script can generate an unlimited number of possible damage combinations for any given parameters with the help of the Monte Carlo (MC) technique. MC helps to generate a random number of damages in random locations at each simulation. Damage conditions are controlled by three parameters including damage severity and damage size (in terms of the mean and standard deviation of damage). Moreover, the method proposes a curve-fitting equation to validate the predicted natural frequency for the first three modes obtained from the neural network model. Both methods are in good agreement with each other, having minimal errors in the range of 0.2-3% for each mode. The frequency result shows that the beam frequency is 8.6486 Hz if the area reduction is 10%, whereas it comes down to 7.2338 Hz if there is a 30% area reduction. A two-level factorial test shows that damage severity is the most impactful factor compared to the damage sizes on the frequency shift event. This indicates that damage alters the composition of the beam and has an impact on its frequency change with the assumed damage parameters. Therefore, the proposed NN model can estimate the frequency shift for various damage scenarios. It can be utilized in the vibration-based damage identification process to predict the frequency changes of the damaged beam without any computational burden.

Analytical investigation of solar parabolic trough receiver with multiple twisted tapes using exergy and energy analysis

Exergy analysis is an important thermodynamic approach to studying the system's actual output, considering all losses. The present study is an analytical approach to calculating the thermal and exergetic efficiencies of the parabolic trough receiver using MATLAB R2018a simulation software. These efficiencies are evaluated considering temperature rise characteristics and parametric design factors. The influence of the solar air heater's thermal and exergy analysis-based mathematical model on all design parameters is examined. The receiver tube has multiple twisted tape inserts with three varying parameters, i.e., twist ratio (y/w) = 3 to 5, perforation ratio (dp/w) = 0.05 to 0.25, and winglet ratio (d/w) = 0.1 to 0.3. The twisted tape with y/w, dp/w, and d/w having values 3, 0.1, and 0.05 perform better regarding energy and exergy with values 84.27% and 4.28%, respectively. This thorough examination can prove to be highly effective and advantageous in generating the design model for the specified twisted tape parameter value without requiring extensive investment in actual experimentation while also furnishing an evaluation of the performance of the solar air heater design.

Possibilities and advantages of additive manufacturing in dry powder formulations for inhalation

In dry powder formulations for inhalation, coarse carrier particles are often used to improve handling, dosing and dispersion of the active pharmaceutical ingredient (API). Carrier particles, mostly alpha-lactose monohydrate crystals, always show a certain size distribution and are never exactly uniform in their geometry. This might be one factor of the rather high invivo variability in fine particle dose from dry powder inhalers. To address the inhomogeneity of carrier particles, additive manufacturing has come to mind. The parametric design of the perfect carrier geometry could further improve the efficiency of dry powder formulations. In this study, a numerical simulation setup using the discrete element method as well as an experimental approach with 3D printed particles were used to determine the loading capacity of a model API onto two different carrier geometries. The difference between the two geometries was reduced solely to their surface's topology to assess the impact of that. The results indicate differences in the loading capacity for the two geometries, depending on the loading process. This study highlights the importance of the carrier geometry for the efficiency of dry powder formulations and thus, strengthens the idea of artificially designed and printed carrier particles.

Parametric Design of a 3D-Printed Removable Common-Mode Trap for Magnetic Resonance Imaging.

Radiofrequency coils are utilized during transmit and receive of MRI signals. Cable traps remove common-mode current from the coaxial cable shield, which helps improve the image quality and reduces risks of burns to the patient. Traditional cable traps use wounded coaxial cables that limit the flexibility in the design process. Floating cable traps were introduced which eliminated any physical connection between the trap and coaxial cable, allowing complete flexibility in design and placement. However, the design process of floating cable traps is iterative and may take several rounds of 3D modeling. This work seeks to optimize the design process through the use of parametric design methodologies. The proposed methodology allows for 3D printing the floating cable trap after inputting the design parameters. The cable trap was able to attenuate currents in the coaxial shields to -48 dB, highlighting its performance and design robustness.

All-dielectric asymmetric planar metasurface based dual-parametric sensor

All-dielectric metasurfaces are a rapidly growing area of research because they have lower ohmic losses and sharper resonances than their metallic equivalents. In this work, we have reported a novel all-dielectric metasurface design for dual parameter (refractive index and temperature) sensing applications. The design consists of a square GaAs block on the top of a quartz substrate with a square hole etched on it. An outer cut to the GaAs block is introduced to break the symmetry. The asymmetry enables a sharp Fano resonance mode with 90% spectral contrast and extremely high quality (Q) factor of value 2.8×104 in the near-infrared (NIR) window. The multipolar nature of the high-Q resonance is studied using the cartesian multipolar decomposition technique, which reveals the electric dipolar nature of the resonance. To examine the refractive index capability of the proposed device, we varied the refractive index of the background medium and found that the device is highly sensitive and results in a very high Figure of Merit (FoM) 5384 RIU−1, owing to the very narrow linewidth of the resonance. The same design is also used for temperature sensing, which shows a notable improvement in sensitivity (72.4 pm/∘C) compared to various existing methods available. The in-depth analysis of the resonance in an optimized all-dielectric metasurface and its potential for sensing presented through this paper can be significant in designing high-performance optical sensors.

Enhanced quadratic DC–DC boost converters with super‐wide voltage gain ranges and ultra‐low voltage stress for renewable energy systems

AbstractAs the promising and ideal clean energies, wind and solar energy systems are in desperate need of high‐performance DC–DC converters to realize efficient and reliable energy transformation. Conventional DC–DC converters for renewable energy systems will work at extreme duty cycles and affect the system efficiency and reliability owing to their limited voltage gains and high‐voltage stress. In this paper, by adopting the hybrid voltage multiplier cells, two enhanced quadratic boost converters (EQBCs) which are highly desirable for renewable energy applications are proposed and analyzed. The EQBCs possess super‐wide voltage gain ranges and ultra‐low voltage stress; therefore, small duty cycle conditions can be achieved and components with low‐rated voltages can be chosen to decrease system volumes and increase system efficiencies. Besides, the EQBCs possess continuous input currents, which can realize small input current ripples and avoid the serious effect of pulsating current on the input sources. What's more, stable output voltages and simple controller circuits are realized by the EQBCs because of the common grounded structures of the input terminal, the single active switch and the output terminal. Detailed principle analyses, parameter designs, performance comparisons and experimental prototypes are conducted to verify the characteristics and feasibilities of the EQBCs.

Sample size planning for multiple contrast tests.

Sample size calculations for two (independent) samples are well established and applied in (pre-)clinical research. When planning several samples, which is common in, for example, preclinical studies, sample size planning tools based on analysis of variance methods are available. Since the underlying effect sizes of these methods are often hard to interpret and to provide for the sample size planning, we employ multiple contrast test procedures for sample size computations in both parametric (under normality assumption) and nonparametric designs using Steel-type tests. Since the exact distributions of the test statistics are unknown under the alternative and variance heterogeneity, we use approximate solutions. Furthermore, since no closed formula for the sample size is available, we use numerical approximations for their computation. Extensive simulation studies are finally conducted to assess the quality of the approximations. It turns out that the methods are accurate in the sense that the multiple contrast test procedures reach the target power to detect the alternative of interest with the sample size computed. The developed procedures are a valuable tool to plan (pre-)clinical trials with several samples and are easily accessible in publicly availablesoftware.

A multi-objective design tool for decarbonising buildings at the concept stage

To enable the move to carbon-neutral building structures with net-zero operation requires a step change in how buildings are designed. Modern buildings are designed by multidisciplinary design teams each of which has competing performance objectives. Daisy is a flexible performance-based parametric design tool which harnesses computational design workflows to enable designer-led multi-objective optimisation, allowing for the design of buildings which simultaneously achieve high performance across multiple performance objectives. A case study of designs for a 63-storey commercial building is presented that demonstrates how early design space analysis facilitates better-performing buildings across architectural and engineering performance metrics and the potential of multi-objective optimisation for enabling the move towards carbon-neutral building structures. Beyond building structures, the design methodology established for Daisy can be applied to a broad range of civil engineering optimisation problems using a flexible and accessible design space formulation that can be adapted for project-specific design requirements. Designs generated using the Daisy methodology demonstrated that by increasing the spatial daylight autonomy of the benchmark building by 14.7%, the building can be moved from the 10% of designs with the highest energy use intensity to lower than 97% of other simulated designs. However, this design change significantly increases the building embodied carbon, with the new design having a building embodied carbon which is higher than 90% of other buildings simulated. Alternatively, by reducing the spatial daylight autonomy by 32.8%, the design can have an energy use intensity which is lower than 75% of other simulated designs, with a 4.4% reduction in energy use intensity, and a building embodied carbon which is lower than 60% of other simulated designs, enabling a 1.3% reduction in building embodied carbon.

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%.

Topology Optimization of Synchronous Reluctance Motors Considering the Optimal Current Reference in the Field-Weakening and Maximum-Torque-Per-Voltage Regions

The torque performance of the synchronous reluctance motors (SynRMs) is primarily determined by the geometric design and current control. The motor structure needs to be designed to yield the maximum output torque under the given current and voltage limitations. The current reference supplied to the stator coils also needs to be determined to maximize the output torque while suppressing the back electromotive force (EMF) to protect a power supply system. However, in the field of design optimization, it has been challenging to simultaneously consider the geometric design and current control due to their complicated relationships. To solve the aforementioned issue, this study proposes a new topology optimization that can cover the maximum-torque-per-ampere (MTPA), field weakening (FW), and maximum-torque-per-voltage (MTPV) controls under both the current and voltage limitations, thereby maximizing the output torque in an entire rotational speed range. To effectively investigate the coupling effects between the geometric design and current reference, this study proposes the design parameterization for the FW and MTPV operation by performing the electromagnetic finite element (FE) analysis and then expresses the optimal current reference in terms of design variables. At every iteration, the structural FE analysis is also performed under the design-dependent loads to obtain a structurally meaningful design. By doing so, both the optimal design and the corresponding optimal current reference can be simultaneously determined. The optimized SynRM is manufactured and experimentally validated to demonstrate the effectiveness of the proposed optimization framework.

Truss bridge design with reclaimed steel elements by performing a stock‐constrained shape and topology optimisation

AbstractTo move up the circular economy hierarchy steel profiles should be reused instead of recycled. To efficiently utilise the limited availability of reclaimed steel elements in new structures, a different approach is required: form follows availability. This paper presents an algorithm for generating truss bridge designs using only reclaimed steel, which optimises material efficiency and avoids cut‐off waste. The algorithm does not require an initial design or a grid of possible positions like the commonly used ground structure method. Instead, it lets a truss geometry grow from start to end. The algorithm was developed using Python in Grasshopper, resulting in a user‐friendly parametric design process. By defining the width and span of a truss bridge and providing a stock of reclaimed elements, a solution cloud of locally optimal truss bridge designs in terms of capacity utilisation is generated, which comply to Eurocode provisions. An optimal design can be selected with given objectives, e.g. the lowest environmental impact. A case study showed that the developed growth method can lead to a truss with 63% less embodied carbon than conventionally designed new steel trusses and 17% less embodied carbon than optimised standard truss designs with retrofitted reclaimed steel elements.

A Clamped IPT System With Adaptive Mode Switching Against Large Coupling Variations

Misalignment issue is almost inevitable in an inductive power transfer (IPT) system, leading to unstable power transfer due to the coupling variations. In order to improve the flexibility of the IPT system, the misalignment range of stable power output is desired to be as large as possible. This paper proposes a clamped IPT system to improve anti-misalignment ability based on the dual-mode operation. The clamped circuit is constructed with a coil and a rectifier connected to the input dc terminal of the inverter. With the effect of the clamped circuit, the operating mode of the system can be adaptively switched to match the required coupling variation region without coupling identification, output detection, or feedback communication. Then, the analysis and parametric design of the system are elaborated. Finally, a 480-W experimental setup was built to verify the feasibility of the proposed method. Experimental results show that the proposed method can maintain stable output power between 440W∼480W with the coupling varying from 0.14 to 0.39, while the efficiency is from 83.22% to 93.55%.

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.