Design Flow Research Articles

Fast Aerodynamic Prediction of Airfoil with Trailing Edge Flap Based on Multi-Task Deep Learning

Conventional methods for solving Navier–Stokes (NS) equations to analyze flow fields and aerodynamic forces of airfoils with trailing edge flaps (TEFs) are known for their significant time cost. This study presents a Multi-Task Swin Transformer (MT-Swin-T) deep learning framework tailored for swift prediction of velocity fields and aerodynamic coefficients of TEF-equipped airfoils. The proposed model combines a Swin Transformer (Swin-T) for flow field prediction with a multi-layer perceptron (MLP) dedicated to lift coefficient prediction. Both networks undergo gradient updates through the shared encoder component of the Swin Transformer. Such a trained network model for computational fluid dynamics simulations is both effective and robust, significantly improving the efficiency of complex aerodynamic shape design optimization and flow control. The study further investigates the impact of integrating multi-task learning loss functions, skip connections, and the network’s structural design on prediction accuracy. Additionally, the effectiveness of deep learning in improving the aerodynamic simulation efficiency of airfoils with TEF is examined. Results demonstrate that the multi-task deep learning approach provides accurate predictions for TEF airfoil flow fields and lift coefficients. The strategic combination of these tasks during network training, along with the optimal selection of loss functions, significantly enhances prediction accuracy compared with the single-task network. In a specific case study, the MT-Swin-T model demonstrated a prediction time that was 1/7214 of the time necessitated by CFD simulation.

Design and experimental analysis of a new vertical ultra-low-head hydro turbine with the variation of outlet flow level on the head drop section of an open canal

Hydropower generation from ultra-low-head water resources is the salient category. The power can be tapped through different non-conventional turbines and is developing these days with different features. This research aims to develop a technology that applies to ultra-low-head resources from conceptualization to laboratory testing. Among several ultra-low-head water resources, it is concentrated on the power generation from the head drop section of the open canal flow through a new hydro turbine. A vertical shaft turbine with an axial flow type of runner having fixed, flat, and constant blade thickness including fixed guide vanes has been designed conventionally for 0.5 m of head and 0.088 m3/s of discharge. Several experiments have been conducted with fixing the level of flow outlet control from 0.0 m to 0.5 m creating the runner from free to submerged conditions is the novelty of this research. The results obtained for all the independent and dependent variables are presented and discussed for a constant flow of 0.088 m3/s and constant speed of 115 rpm conditions. The uncertainty on measurement was found ±1.85 % and the overall maximum efficiency obtained was 53.8 % for flow 10 % above the design flow. The research has concluded the use of outlet flow control is necessary to achieve the maximum efficiency of the turbine at a specific height and the overall efficiency can be advanced further through the optimization of blade profile.

HLS-IRT: Hardware Trojan Insertion through Modification of Intermediate Representation During High-Level Synthesis

Modern integrated circuit (IC) design incorporates the usage of proprietary computer-aided design (CAD) software and integration of third-party hardware intellectual property (IP) cores. Subsequently, the fabrication process for the design takes place in untrustworthy offshore foundries that raises concerns regarding security and reliability. Hardware Trojans (HTs) are difficult to detect malicious modifications to IC that constitute a major threat, which if undetected prior to deployment, can lead to catastrophic functional failures or the unauthorized leakage of confidential information. Apart from the risks posed by rogue human agents, recent studies have shown that high-level synthesis (HLS) CAD software can serve as a potent attack vector for inserting Hardware Trojans (HTs). In this paper, we introduce a novel automated attack vector, which we term “HLS-IRT”, by inserting HT in the register transfer logic (RTL) description of circuits generated during a HLS based IC design flow, by directly modifying the compiler-generated intermediate representation (IR) corresponding to the design. We demonstrate the attack using a design and implementation flow based on the open-source Bambu HLS software and Xilinx FPGA, on several hardware accelerators spanning different application domains. Our results show that the resulting HTs are surreptitious and effective, while incurring minimal design overhead. We also propose a novel detection scheme for HLS-IRT, since existing techniques are found to be inadequate to detect the proposed HTs.

Optimized and Automated Secure IC Design Flow: A Defense-in-Depth Approach

Optimized and Automated Secure IC Design Flow: A Defense-in-Depth Approach

Trajectory optimization of B-splines interpolation based on dynamic error adjustment

In this paper, we propose a motion planning algorithm based on the five-fold B-spline curve for multi-axis motion control systems with non-smooth trajectories, acceleration, plus acceleration over the limit, etc. We construct a smooth transition model for the micro-line segment G3 of the continuous five-fold B-spline curve. A derivation of the corresponding theoretical equation is given. Using the transition model, we propose an optimization method for dynamic adjustment of motion trajectory errors based on the velocity forward planning constraints by smoothing the transition after the trajectory of the micro-line segment for the forward planning velocity. Finally, the design flow for the forward planning of the velocity is given. Finally, the above algorithm is used to perform simulation experiments for the optimization algorithm. Experimental results show that the proposed optimization improves the accuracy of fitting motion trajectories under the constraints of acceleration and deceleration addition, which validates the proposed algorithm.

Design and Test of Offset Quadrature Phase-Shift Keying Modulator with GF180MCU Open Source Process Design Kit

This article explores the evolution of integrated circuits (ICs), highlighting the fundamental role of open source Electronic Design Automation (EDA) tools in their development. It describes the IC’s design flow, differentiating between Front-end and Back-end design stages, and details the process of implementing the digital stage in offset quadrature phase-shift keying (OQPSK) modulation in an IC, including its hardware description language (HDL), the implementation test in the field-programmable gate array (FPGA), and the physical layout using the first manufactured open source process design kits (PDKs) in Global Foundries’ 180 nm, as well as the use of OpenLane and Caravel. To conclude, the results of the physical tests obtained from the digital modulation are presented, as well as the performance of the raised cosine shaping filter.

Application of circuit model for gap-plasmon nanodisk resonators

The design of plasmonic metasurfaces is often based on solving the Maxwell electromagnetic equations, which can be a time-consuming and expensive process considering many geometrical parameters that can limit design flexibility. To speed up the design flow, a model based on the classical transmission line theory is presented. The proposed equivalent circuit model can predict the plasmon resonance wavelength based on various geometrical parameters including dielectric thickness and disk diameter. In addition, unlike other reported circuit models, the developed model considers the nanostructure array pitch size, which is crucial in metasurface design. Comparison between the results obtained from circuit model and full wavelength simulation showed that the circuit parameters accurately determine the response of the structure. Finally, as a metasurface design demonstration, we utilized our model to simulate aluminum-based gap-plasmon nanodisk arrays for optimizing their optical response to maximize structural color saturation.

TITAN: Combining a bidirectional forwarding graph and GCN to detect saturation attack targeted at SDN.

The decoupling of control and forwarding layers brings Software-Defined Networking (SDN) the network programmability and global control capability, but it also poses SDN security risks. The adversaries can use the forwarding and control decoupling character of SDN to forge legitimate traffic, launching saturation attacks targeted at SDN switches. These attacks can cause the overflow of switch flow tables, thus making the switch cannot forward benign network traffic. How to effectively detect saturation attack is a research hotspot. There are only a few graph-based saturation attack detection methods. Meanwhile, the current graph generation methods may take useless or misleading information to the attack detection, thus decreasing the attack detection accuracy. To solve the above problems, this paper proposes TITAN, a bidirecTional forwardIng graph-based saturaTion Attack detectioN method. TITAN defines flow forwarding rules and topology information, and designs flow statistical features. Based on these definitions, TITAN generates nodes of the bi-forwarding graph based on the flow statistics features and edges of the bi-forwarding graph based on the network traffic routing paths. In this way, each traffic flow in the network is transformed into a bi-directional forwarding graph. Then TITAN feeds the above bidirectional forwarding graph into a Graph Convolutional Network (GCN) to detect whether the flow is a saturation attack flow. The experimental results show that TITAN can effectively detect saturation attacks in SDNs with a detection accuracy of more than 97%.

Impact of Station Design and Passengers Flow on Urban Rail Dwell Time: A Systemwide Analysis Using APC and AVL Data

In this paper, we investigated the impact on dwell time of station design, train load, and passenger flow, considering boarding fraction. We employed system-wide automated data sources including automatic passenger counting and automatic vehicle location data in the rail transit system in Calgary, Canada. Regression analyses were conducted to achieve accurate dwell time estimation by calculating passenger load per car, boarding, and alighting passengers per door, and also identifying the critical door with the highest demand. Observations for each critical door were divided based on the fraction of boarding passengers with respect to the sum of boarding and alighting. Six stations with distinct geometric designs were selected for comparison to assess their impact on dwell time. The results indicate that, for dominant boarding or alighting, a longer time is needed per passenger to alight or board, respectively. Our findings indicate that a station with a middle platform and two entrances positioned in the middle performed better in terms of dwell time in the case of alighting-dominant and mixed passenger flow. For stations experiencing boarding-dominant passenger flows, side platforms with multiple entrances at the ends and middle outperformed. Narrower platforms experienced significantly longer dwell times than other selected stations under similar demand. While the conclusion about the station design may not be generic, the proposed model provides a consistent and adaptable approach to study the impact of station design and passenger flows on urban rail dwell times, facilitating better-informed decision-making for station design or modification and enhancement of the overall rail system performance.

Unified design flow for facilitating fast Li kinetics in layered oxide cathodes

Fast charging is desirable for the global use of full electric vehicles (EVs); however, it faces challenges based on Li kinetics. A structural design based on the electrostatic repulsion (ER) between cations over the full charging process is proposed herein to facilitate the fast Li kinetics of LiMO2 (M = transition metal) layered oxides in lithium-ion batteries (LIBs). This process is divided into two steps under the Li kinetic mechanism, in which LiO4 is a transition state upon migration. First, changing the O3- to O2-type layered cathodes causes the expansion of the LiO2 slab and elimination of the ER between Li and M ions in the hidden space based on the edge-shared mode for the Li-abundant region. Second, expanding the LiO4 space to release the stressed environment provides easy accommodation of Li ions through the ionic radius of the dopants in the Li-deficient region. Using unified atomistic calculations of density functional theory and kinetic Monte Carlo simulations, the systematic design flow can be understood in terms of the structural parameters, site energetics for the kinetic barrier, and statistical transitions based on various Co-based LiMO2 models. Our concrete understanding of local-to-macroscopic structural scales suggests a generalized direction for facilitating fast Li kinetics for realizing fast-charging LIBs.

The Role of Fashion Illustration as a Communicative Tool in Design

This qualitative study investigates fashion illustration's role as a conceptual communication tool within Ghana's developing design education landscape through interviewing 5 fashion lecturers and 10 undergraduate students. The thematic analysis uncovers multifaceted pedagogical and socio-cultural functions of illustration in nurturing students' cultural visual literacies, critical perspectives, and creative confidence during early design stages. Perspectives highlight persistent challenges balancing mainstream global aesthetics and meaningful representations of local cultural traditions and identities across the curriculum. Findings provide empirically grounded, localized insights on leveraging this visual medium to bridge modernity and tradition at the intersection of Ghana's emerging formal fashion infrastructures and dynamic transnational design flows. Foregrounding Ghanaian voices shape the understanding of how hybridity manifests through selectively integrating foreign illustration techniques to nurture local relevance. Interpretations posit illustration's capacity to strengthen pluralistic communication and identity expression anchored in indigenous visual culture yet resonating globally. This exploratory study constitutes an early step toward decolonizing African design pedagogies by elevating Ghanaian standpoints and creative-educational priorities to enrich conceptual communication functionality. Wider survey and comparative research can further generalize and contextualize findings toward this long-term goal.

Design and Simulation of the Biodiesel Process Plant for Sustainable Fuel Production

The biodiesel production process is extensively studied in the literature, focusing on mechanisms, modeling, and economic aspects, yet plant design and fluid flow losses remain underexplored areas. The study addressed this gap by designing a biodiesel production plant, analyzing flow losses, and developing a pipe network and suitable pump models. In this study, an integration of biodiesel production plant design and simulation of continuous production of Calophyllum inophyllum biodiesel was investigated. Biodiesel production encompasses complex stages that involve systematic planning and system design. The goal of the plant design is to reduce the losses that occur during the conversion process, which can reduce the capital cost of the plant. A few assumptions were made when selecting biodiesel plant materials, such as pipes, pumps, fittings, and bends. These assumptions were based on considerations of the biodiesel fluid properties and pressure requirements. On the other hand, Aspen Plus was used to simulate the biodiesel production process. Calophyllum inophyllum was considered oil as the biodiesel feedstock and was inputted to the Aspen Plus as triglyceride composition. The simulation was carried out with rigorous kinetic reactions using the Non-Random Two-Liquid (NRTL) method to predict the liquid equilibrium in the reactor. Results revealed that the designed steel pipe meets safety requirements with a bursting pressure of 49.68MPa, capable of withstanding the maximum pressure of 4 bar and turbulent flow conditions. Additionally, the selected pump satisfies the required head and flow rate, ensuring efficient fluid movement. Moreover, simulation results closely matched experimental data, and 88% of biodiesel yield was recorded.

Flood frequency analysis using mean daily flows vs. instantaneous peak flows

Abstract. In many cases, flood frequency analysis (FFA) needs to be carried out on mean daily flows (MDF) instead of instantaneous peak flows (IPF), which can lead to underestimation of design flows. Typically, correction methods are applied to the MDF data to account for such underestimation. In this study, we first analyse the error distribution of MDF-derived flood quantiles over 648 catchments in Germany. The results show that using MDF instead of IPF data can lead to underestimation of the mean annual peak flow (MHQ) by up to 80 % and mainly depends on the catchment area but appears to be influenced by gauge elevation as well. This relationship is shown to differ for summer vs. winter floods. To correct such underestimation, different linear models based on predictors derived from MDF hydrograph and catchment characteristics are investigated. Apart from the catchment area, a key predictor in these models is the event-based ratio of flood peak to flood volume (p/V ratio) obtained by the MDF data. The p/V models applied to either MDF-derived events or statistics seem to outperform other reference correction methods. Moreover, they require a minimum data input, are easily applied, and are valid for the entire study area. The best results are achieved when the L moments of the MDF maximum annual series are corrected with the proposed model, which reduces the flood quantile errors by up to 60 %. The approach behaves particularly well in smaller catchments (<500 km2), where reference methods fall short. However, the limit of the proposed approach is reached for catchment sizes under 100 km2, where the hydrograph information from the daily series is no longer capable of approximating instantaneous flood dynamics and gauge elevations below 100 m, where the difference between MDF and IPF floods is very small.

Process intensification in flow chemistry using micro and millidevices: Numerical simulations of the syntheses of three different intermediate API compounds for diabetes mellitus drug production

Microreactor Technology (MRT) appears as an interesting alternative for process intensification, including the development of continuous synthesis of fine chemicals and Active Pharmaceutical Ingredients (API). The inherent proposal of MRT is to reduce the scale-up time by simply increasing the number of microreactors in parallel, the numbering-up concept using optimal designed micro or millidevices. Among the API, rosiglitazone and lobeglitazone are derivatives of thiazolidine-2,4-dione (TZD), which is used as a building block, for molecules with biological activity, sensitive to insulin and, thus, with its administration the body makes better use of the insulin it produces, being an important structural element in medicinal chemistry, especially for type 2 diabetes mellitus, one of the biggest concerns in the health area worldwide, affecting nowadays more than 180 million people. The numerical assessment of MRT for various API synthesis related to type 2 diabetes mellitus drugs indicates its comparable or superior performance compared to traditional batch process. Specifically, proposed micromixer designs facilitate successful scale-up to milliscale while maintaining microscale performance, with significantly lower pressure drops than commercial Asia microreactors. The proposed flow distributors offer good performance in ensuring uniform distribution across outlets due to their conical shape design and laminar flow regime, with low pressure drops. The flow distributor with eights outlet is preferred for higher flow rates due to its superior performance, minimizing the pressure drops. Efficient flow rate and molar concentration control at each reactor unit can be ensured by using one distributor for each reactant's feed stream. This approach guarantees accurate concentration, flow rate control and ideal residence time, ultimately facilitating higher total throughput for scale-up. The potential use of micromixer actuators lies in its ability to maintain or enhance performance while transitioning from micro to milli-scale, offering promising alternatives for process intensification and scale-up in pharmaceutical synthesis, particularly for medications targeting type 2 diabetes mellitus.

Enhancing the microwave absorption performance of graphite/Al2O3 composites through manipulating sheet resistance

AbstractThe graphite/Al2O3 composite was prepared using plasma spray technology, the material design, experimental methods, and process flow are introduced. The microstructure, chemical composition, and complex permittivity of the composite are investigated, and its performance to absorb electromagnetic waves is studied. The mechanism of interaction between chemical composition, microstructure, complex permittivity, and absorption performance is analyzed. Furthermore, a microwave absorber composed of graphite/Al2O3 and sheet resistance, and performance is discussed. The reflectivity of the composite coating with different periods and sizes and resistances is analyzed. The impedance and reflectivity of the designed absorber that contains sheet resistance are discussed, and its absorption mechanism is explained in detail. The results demonstrate that the microwave absorption performance of graphite/Al2O3 coating is enhanced by electromagnetic resonance of the sheet resistance. The designed absorber exhibits good wave‐absorbing performance and stability at the frequency of the 8.2–18 GHz range. When the sample thickness is 2.3 mm, the absorber achieves a reflection loss (RL) value of −16.8 dB at 9.8 GHz and a wide effective absorption bandwidth (EAB) of 9.8 GHz. It means that the RL below −10 dB can be obtained in the whole X band and Ku bands. These results proved that the EAB can be tuned and enhanced by manipulating sheet resistance.

Design of low-cost digital pulse processing unit for gamma spectrometry

Gamma spectrometers are used to quantify and identify radioisotopes in the sample under test. There is a recent interest around the world in implementing low-cost gamma spectrometers. One of the main parts of the modern gamma spectrometer is the digital pulse processing unit (DPP). The implementation of this unit using advanced microcontroller chips has appeared in recent years as an attractive approach. This is due to its advanced performance and low cost. In this paper, we present a design flow to implement a DPP unit using an ARM Cortex-M3-based microcontroller chip. The sodium iodide detector is the targeted detector for this design. Our prototype is approved experimentally to construct spectrums comparable to commercial devices. And it can cope with input count rates up to 45 kC/s.

Efficient electrosynthesis of HO2- from air for sulfide control in sewers

Electrochemically in-situ generation of oxygen and caustic soda is promising for sulfide management while suffers from scaling, poor inactivating capacity, hydrogen release and ammonia escape. In this study, the four-compartment electrochemical cell efficiently captured oxygen molecules from the air chamber to produce HO2- without generating toxic by-products. Meanwhile, the catalyst layer surface of PTFE/CB-GDE maintained a relatively balanced gas-liquid micro-environment, enabling the formation of enduring solid-liquid-gas interfaces for efficient HO2- electrosynthesis. A dramatic increase in HO2- generation rate from 453.3 mg L-1 h-1 to 575.4 mg L-1 h-1 was attained by advancement in operation parameters design (flow channels, electrolyte types, flow rates and circulation types). Stability testing resulted in the HO2- generation rate over 15 g L-1 and the current efficiency (CE) exceeding 85%, indicating a robust stable operational capacity. Furthermore, after 120 mg L-1 HO2- treatment, an increase of 11.1% in necrotic and apoptotic cells in the sewer biofilm was observed, higher than that achieved with the addition of NaOH, H2O2 method. The in-situ electrosynthesis strategy for HO2- represents a significance toward the practical implementation of sulfide abatement in sewers, holding the potential to treat various sulfide-containing wastewater.

Air entrainment by a hydrofoil in a high-speed water flow for design of bubbly drag reduction ships

We have investigated the flow behavior around a hydrofoil bubble generator in a high-speed channel flow up to 10 m/s for the first time to understand the air entrainment characteristics of this hydrofoil device caused purely by the inertia effect of water flow. This study is motivated by our previous success in achieving ship drag reduction for full-scale vessels (Kumagai et al., 2015). Depending on the water flow velocity U and the angle of attack of the hydrofoil α, three different major patterns were identified: continuous generation of dispersed bubbles, intermittent formation of an air cavity, and steady formation of a super air cavity that stretched behind the hydrofoil. The transition from the dispersed bubble state to the air cavity formation regime is explained theoretically using the equation of bubble motion coupled with a potential flow analysis. The air volume flow rate increased linearly with U, and its slope was steeper in the dispersed bubble state than in the air cavity formation regime. The highest air flow rate was realized at U = 9 m/s, which corresponds to the nominal air layer thickness at ta = 4.1 mm, and reaches the feasible range for realization of bubbly drag reduction for a long ship hull.

Experimental Study of Lubricant Distribution and Lubrication Enhancement Induced by Ball Bearing Cage

Abstract The bearing cage played a pivotal role in affecting the lubricant redistribution and lubrication states. In this study, a cage unit is incorporated into an optical ball-on-disc apparatus for the purpose of a quantitative study of cage-induced lubrication phenomena. It is found that the presence of the lubricant layer on the ball surface, shaped by the cage, affects the inlet lubricant supply of contact between the ball and the glass disc. Thereafter, the oil reservoirs surrounding the contact area and the film thickness were measured. The results showed that the lubricant reservoirs and inlet lubricant supplement were significantly improved with the employment of the cages. In addition, the lubrication state transformed from starved to fully flooded, effectively enhancing the lubrication state. Moreover, the lubricant on the steel ball surface moved from the side bands to the central rolling track, indicating that the lubricant redistribution was the main reason for the lubricating enhancement. Notably, the groove modification on the inner surface of the cage pocket facilitated the directional lubricant migration and the migration effect depended on the groove angles. In conclusion, these results offer an in-depth understanding of the bearing lubrication mechanism, thereby inspiring advancements in cage design and lubricant flow regulation.

Solar-hydro cable pooling – Utilizing the untapped potential of existing grid infrastructure

Over the years, the coupling of various variable renewable energy sources has emerged as a convenient way to partially or fully overcome their highly intermittent nature and low-capacity factors. In literature as well as in practical implementations, the coupling of solar and wind power systems is gaining special attention thanks to their advantageous complementarity in time. However, an area of yet not well-documented potential is the coupling of solar PV plants with non-dispatchable run-of-river hydropower plants. In this study, Poland, which still has significant untapped hydropower potential, is used as a case study. The objective of the work is to quantify the coupling potential with special attention paid to the unavoidable curtailment of solar generation due to the limited grid connection capacity. A simulation model was developed that uses input runoff, irradiation, and temperature hourly data covering the period 01.01.2008–31.12.2022 for 236 selected sites in Poland. Hydrological data were obtained from field measurements, while the remaining meteorological parameters were downloaded from the ERA5 reanalysis database. Hydropower generation was simulated assuming a constant head and a Kaplan turbine operating at different efficiencies depending on the flow rate through the turbine. The available flow was calculated considering environmental flow (e-flows) constraints. The design flow was determined based on the average multi-year flow in the considered river. The complementarity in time of these two renewable energy sources in each location was assessed by considering the grid connection capacity and resulting curtailment in case of too high simultaneous generation from both sources. The analysis showed that the average PV curtailment is about 10.7 % (or 13.2 % when it is solar PV capacity weighted) when the ratio of solar to hydro is equal. Still, it can be as high as 19.7 % in individual cases. To ensure that PV curtailment is no more than arbitrarily (in that case) selected threshold of 5 %, the solar-PV capacity should be between 58 % − 120 % of the designed hydropower plant capacity. The curtailment threshold can be further investigated as an expansion of a techno-economic analysis that fell out of the scope of this work. The additional analysis conducted by means of daily flow data showed a significant underestimation of solar curtailment in individual cases (i.e., up to 7 pp.) and, on average, lower by 0.24 pp. could be expected. Due to interannual flow variations, although the expected mean solar curtailment can be no more than 5 %, there are individual years when it is as low as 2 % and as high as 12 % of this year’s solar generation. The lessons learned from this study shed light on the potential maximization of local power generation through coupling with PV systems and the simultaneous reduction of environmental impacts by releasing higher quantities of e-flows offset by the integration of PV systems.