Modular Design Approach Research Articles

Design and Control of a Novel Variable Stiffness Series Elastic Actuator

This article expounds the design and control of a new variable stiffness series elastic actuator (VSSEA). It is established by employing a modular mechanical design approach that allows us to effectively optimize the stiffness modulation characteristics and power density of the actuator. The proposed VSSEA possesses the following features: no limitation in the work range of output link; a wide range of stiffness modulation (∼20 N·m/rad to ∼1 KN·m/rad); low-energy-cost stiffness modulation at equilibrium and nonequilibrium positions; compact design and high torque density (∼36 N·m/kg); and high-speed stiffness modulation (∼3000 N·m/rad/s). Such features can help boost the safety and performance of many advanced robotic systems, e.g., a cobot that physically interacts with unstructured environments and an exoskeleton that provides physical assistance to human users. These features can also enable us to utilize variable stiffness property to attain various regulation and trajectory tracking control tasks only by employing conventional controllers, eliminating the need for synthesizing complex motion control systems in compliant actuation. To this end, it is experimentally demonstrated that the proposed VSSEA is capable of precisely tracking the desired position and force control references through the use of the conventional proportional–integral–derivative controllers.

Light-driven biosynthesis of volatile, unstable and photosensitive chemicals from CO2

Directing CO2 conversion using photoautotrophic microbes offers a promising route to coupling carbon mitigation with petrochemical replacement. However, solar-based biomanufacturing is hampered by inefficient genetic manipulation, narrow product scope and light-induced decomposition. Here we report a spatiotemporally separated modular strategy to realize CO2-to-molecule conversion by sequentially linking carbon sequestration and cellular catalysis via stable mediator compounds. The carbon fixation rate of the sequestration module was improved by approximately 50% through metabolic network remodelling, while biphasic catalysis, multiple gene editing and high-throughput workflow were applied to the catalysis modules to produce olefins, cinnamaldehyde and curcumin. The catalytic efficiency was notably enhanced by up to 114-fold compared with the monoculture. This modular design approach enables the rapid development of sustainable biorefineries in a plug-and-play fashion, as evidenced by the production of various chemicals at the gram-per-litre level through scaled-up fermentation. This carbon-negative flexible platform notably widens the applicability of light-driven biosynthesis and may boost the bioindustry of CO2 reduction in a sustainable future. Carbon-negative biomanufacturing is typically hampered by narrow product scope and light-induced decomposition. Now, an integrated photosynthetic carbon sequestration and cellular catalysis strategy for CO2 valorization are reported. Multiple gene editing and a high-throughput workflow have facilitated its application to the biocatalytic production of styrene, intracellular unstable aldehydes and photosensitive molecules from CO2.

Experimental thermal characterization of the in-wheel electric motor with loop heat pipe thermal management system

Current trends in technology toward the elimination of fossil fuels are increasing the value of electric vehicles (EVs). In turn, one of the main components of EVs is an electric motor (EM). The lifetime, reliability and output power of the EMs depend on the performance of their cooling systems. The cooling systems that are based on two-phase technologies of heat transfer, such as loop heat pipes (LHPs), have important advantages over traditional air- and liquid systems. On the other hand, LHP EM thermal control application is slowed down by the complication of their manufacturing and high production expenses. However, in recent years, new technologies are constantly being developed that can reduce the customization of LHP and, therefore, the cost of its production. In this paper the technology based on modular standardized approach for LHP design and manufacturing is applied to demonstrate the cooling performance of LHP in an in-wheel motor of a personal mobility vehicle (electric bike, wheelchair etc.) and compare it to the standard cooling solution. For this purpose, a double-capillary pump unit evaporator LHP was produced and coupled with an EM. EM thermal characteristics were studied and compared to the values obtained prior to LHP installation. Studies have shown that the use of two-phase cooling can increase motor performance up to 2.5 times.

Indoor Single‐Component Organic Solar Cells Based on Double‐Cable Conjugated Polymers with Pendant A‐π‐D‐π‐A Electron Acceptors

Herein, three double‐cable conjugated polymers are developed for indoor single‐component organic solar cells (SCOSCs). The new double‐cable conjugated polymers contain pendent nonfused electron acceptors with A‐π‐D‐π‐A configuration, in which group A uses 1H‐indene‐1,3(2H)‐dione (ID) as an electron‐withdrawing end group. The innovative design enables the double‐cable polymer to show absorption spectra in the range of 400–700 nm, which is matched with the spectra of indoor light‐emitting diode lights. In addition, the ID units at the acceptor side units and the introduction of halogen atoms make the double‐cable polymers show high photovoltage (>1.0 V) in SCOSCs. As a result, SCOSCs based on the new double‐cable polymers exhibit a high efficiency of 18% under indoor light illumination. The findings present a novel modular design approach for wide‐bandgap double‐cable conjugated polymers that can be utilized for indoor photovoltaics.

Multi-Reconfigurable DNA Origami Nanolattice Driven by the Combination of Orthogonal Signals.

The progress of the scaffolded DNA origami technology has enabled the construction of various dynamic nanodevices imitating the shapes and motions of mechanical elements. To further expand the achievable configurational changes, the incorporation of multiple movable joints into a single DNA origami structure and their precise control are desired. Here, we propose a multi-reconfigurable 3 × 3 lattice structure consisting of nine frames with rigid four-helix struts connected with flexible 10-nucleotide joints. The configuration of each frame is determined by the arbitrarily selected orthogonal pair of signal DNAs, resulting in the transformation of the lattice into various shapes. We also demonstrated sequential reconfiguration of the nanolattice and its assemblies from one into another via an isothermal strand displacement reaction at physiological temperatures. Our modular and scalable design approach could serve as a versatile platform for a variety of applications that require reversible and continuous shape control with nanoscale precision.

Craft-and-Stick Xurographic Manufacturing of Integrated Microfluidic Electrochemical Sensing Platform

An innovative modular approach for facile design and construction of flexible microfluidic biosensor platforms based on a dry manufacturing "craft-and-stick" approach is developed. The design and fabrication of the flexible graphene paper electrode (GPE) unit and polyethylene tetraphthalate sheet (PET)6/adhesive fluidic unit are completed by an economic and generic xurographic craft approach. The GPE widths and the microfluidic channels can be constructed down to 300 μm and 200 μm, respectively. Both units were assembled by simple double-sided adhesive tapes into a microfluidic integrated GPE (MF-iGPE) that are flexible, thin (<0.5 mm), and lightweight (0.4 g). We further functionalized the iGPE with Prussian blue and glucose oxidase for the fabrication of MF-iGPE glucose biosensors. With a closed-channel PET fluidic pattern, the MF-iGPE glucose biosensors were packaged and sealed to protect the integrated device from moisture for storage and could easily open with scissors for sample loading. Our glucose biosensors showed 2 linear dynamic regions of 0.05-1.0 and 1.0-5.5 mmol L-1 glucose. The MF-iGPE showed good reproducibility for glucose detection (RSD < 6.1%, n = 6) and required only 10 μL of the analyte. This modular craft-and-stick manufacturing approach could potentially further develop along the concept of paper-crafted model assembly kits suitable for low-resource laboratories or classroom settings.

Memristor-Based Light-Weight Transformer Circuit Implementation for Speech Recognizing

Transformer network (TN) is a promising model widely used for natural language processing (NLP), computer vision (CV), and audio processing (AP). However, the large number of multiples and additions (multi-adds) in TN leads to a massive number of parameters in the TN model, causing an increasing number of hardware resource overhead and thus making it difficult to deploy the TN model to edge devices. To alleviate this problem, this paper proposes a circuit implementation scheme for a memristor-based lightweight transformer network (MLTN). In addition, the speech recognition task based on the speech command dataset is implemented through the modular hardware design approach, which provides an effective lightweight hardware implementation scheme for the edge devices. Further, the retention, noise immunity, variability, and stability of the designed circuit are analyzed by simulation experiments with LTSPICE. The results show that the proposed MLTN circuit not only has a lighter network model but also has significant recognition accuracy with different hardware scales. Specifically, MLTN-40 can achieve 96.18% simulation accuracy, while the energy overhead is only 3.8% of the ARM framework, which is commonly used for edge devices, and 39.9% of the traditional server (GPU), making it a promising solution for implementing speech recognition on edge devices.

OWEFE—open modeling framework for integrated water, energy, food, and environment systems

The integrated approach to managing the fundamental resources for human life, namely, water, energy, food, and the environment as their irreplaceable foundation, presents a profound opportunity for sustainable development. However, despite their huge potential, integrated water, energy, food, and environment systems (iWEFEs) are rarely put into practice because of, among others, complexity and a lack of uniform and openly available models to describe, configure and simulate such systems. To fill this gap, we present the open modeling framework for integrated water, energy, food, and environment systems (OWEFEs) based on the open energy modeling framework. OWEFE follows an open, cross-sectoral, and modular design approach to address crucial challenges for the project development of iWEFEs. In this study, we apply OWEFE for the first time to model a wastewater biogas system and an agrivoltaics system. The results of the OWEFE-based models are in the range of a conventional approach respectively of on-site measurements indicating the framework’s capability to model diverse iWEFEs. The wide application of the framework can improve the assessment, planning, and configuration of iWEFEs for sustainable and integrated infrastructure development.

Physics-based approach to extend a de novo TIM barrel with rationally designed helix-loop-helix motifs.

Computational protein design promises the ability to build tailor-made proteins de novo. While a range of de novo proteins have been constructed so far, the majority of these designs have idealized topologies that lack larger cavities which are necessary for the incorporation of small molecule binding sites or enzymatic functions. One attractive target for enzyme design is the TIM-barrel fold, due to its ubiquity in nature and capability to host versatile functions. With the successful de novo design of a 4-fold symmetric TIM barrel, sTIM11, an idealized, minimalistic scaffold was created. In this work, we attempted to extend this de novo TIM barrel by incorporating a helix-loop-helix motif into its βα-loops by applying a physics-based modular design approach using Rosetta. Further diversification was performed by exploiting the symmetry of the scaffold to integrate two helix-loop-helix motifs into the scaffold. Analysis with AlphaFold2 and biochemical characterization demonstrate the formation of additional α-helical secondary structure elements supporting the successful extension as intended.

Overview of Integration of Power Electronic Topologies and Advanced Control Techniques of Ultra-Fast EV Charging Stations in Standalone Microgrids

For longer journeys, when drivers of electric vehicles need a charge on the road, the best solution is off-board ultra-fast chargers, which offer a short charging time for electric vehicle batteries. Consequently, the ultra-fast charging of batteries is a major issue in electric mobility development globally. Current research in the area of power electronics for electric vehicle charging applications is focused on new high-power chargers. These chargers will significantly increase the charging power of electric vehicles, which will reduce the charging time. Furthermore, electric vehicles can be deployed to achieve improved efficiency and high-quality power if vehicle to microgrid (V2µG) is applied. In this paper, standards for ultra-fast charging stations and types of fast charging methods are reviewed. Various power electronic topologies, the modular design approach used in ultra-fast charging, and integration of the latter into standalone microgrids are also discussed in this paper. Finally, advanced control techniques for ultra-fast chargers are addressed.

Physical Simulator for Colonoscopy: A Modular Design Approach and Validation

Simulators for gastrointestinal (GI) endoscopy offer the opportunity to train and assess clinician skills in a low-risk environment. Physical simulators can enable direct instrument-to-organ interactions not provided by virtual platforms. However, they present scarce visual realism and limited variability in their anatomical conditions. Herein, we present an innovative and low-cost methodology for the design and fabrication of modular silicone colon simulators. The fabrication pipeline envisages parametric customization and development of 3D-printed molds for silicon pouring to obtain colon segments. The size of each colon segment is based on clinical data extracted from CT colonography images. Straight and curved segments are connected through silicone conjuncts to realize a customized and modular monolithic physical simulator. A 130 cm-long colon simulator prototype with assorted magnetically-connected polyps was fabricated and laid on a custom-made sensorized abdominal phantom. Content, face and construct validity of the designed simulator were assessed by 17 GI endoscopists. In summary, this work showed promising results for improving accessibility and flexibility of current colonoscopy physical simulators, paving the way for modular and personalized training programs.

Roadmap for Deployment of Modularized Hydrothermal Liquefaction: Understanding the Impacts of Industry Learning, Optimal Plant Scale, and Delivery Costs on Biofuel Pricing

Hydrothermal liquefaction (HTL) is a promising technology for converting abundant organic wastes into fuels. Previous techno-economic analyses (TEAs) of HTL have been used to estimate the minimum fuel selling price (MFSP) of biofuel products, but these analyses often assume a bespoke plant design where each plant operates under unique process conditions and neglect transportation costs. However, transportation costs must be included in realistic TEAs, and further, a mass-produced fixed-scale modular plant design approach may be more effective than case-by-case plant design, provided that there is sufficient market capacity to benefit from modularization. This study estimates fuel price behavior in the presence of transportation costs and benefits stemming from modular plant design. This analysis indicates that a modular process capable of handling 60 dry tons per day (DTPD) is optimal, resulting in a ∼25% reduction in MFSP (from $4.70/GGE, fully upgraded) at complete market feedstock utilization compared with case-by-case design. The associated cost reductions are attributable to learning benefits and modularization. Several HTL deployment “roadmaps” are then explored, with each roadmap consisting of different periods of case-by-case design followed by adoption of a modularized approach. A period of nonmodular industry growth up to market saturation of ∼7% followed by implementation of modular plant design strikes a balance between the investment risk and learned cost reductions associated with modular plant design. However, if bespoke plants built during this period of nonmodular growth saturate more than 23% of available feedstock, learned cost reductions are significantly diminished. This study points to the potential benefits of modularized and decentralized waste-to-energy processes when the modularization follows an optimal deployment strategy.

A modular design approach to polymer-coated ZnO nanocrystals

Hybrid materials based on inorganic nanocrystals with organic polymers featurepeculiar and fascinating properties and various applications. However, there is still a need for simple synthesis procedures that provide precise control over the polymer/nanocrystal microstructure of these materials. Herein, a novel organometallic approach to polymer-coated ZnO nanocrystals was developed. The presented method merges the initial ring-opening polymerization of ϵ-caprolactone mediated by an organozinc alkoxide initiator and an air-promoted transformation of the resulting macromolecular organozinc species. This one-pot procedure results in quantum-sized ZnO crystals with a core diameter of ca 3nm coated by poly(ϵ-caprolactone) covalently bonded to the surface. Overall, the ability to create well-defined hybrid composites should provide a unique ability to access various nanosystems.

Analog Compatible Logic Functions Using EXCCIIs and an Extended Application for Sigmoid Activation Function

This paper introduces the use of an extra X current conveyor (EXCCII) for realizing logic operations, suited for mixed signal design, without necessitating separate digital blocks. The NOR and OR logic functions are thus shown to be realized using the current-mode analog building block operable at a low voltage. The use of [Formula: see text][Formula: see text]V supply makes the new circuits operable at low voltage. The EXCCII bias current used in the design is 25[Formula: see text][Formula: see text]A. The input currents for defining logic 0 and logic 1 are, respectively, taken as 0[Formula: see text]mA and 0.5[Formula: see text]mA. The proposed circuits’ delay is found to be 10[Formula: see text]ns for low-to-high transition, while 2[Formula: see text]ns for high-to-low transition for NOR gate under capacitive loading conditions. The use of the current-mode approach makes the new proposed circuit apt for current-mode signal processing. The new proposed logic function circuits are compatible with analog circuits, thus providing an easy merger for mixed signal systems design, paving the way to a modular design approach. As an extended application in artificial neural networks, the proposed circuit is shown to generate a sigmoid activation function with convincing results. Several results are included by varying the reference current, and the circuit’s robustness aspect is also tested in the presence of fluctuation in the bias current of EXCCII. The novel approach of utilizing an analog building block for realizing digital functions is, therefore, verified with promising future applications.

Putting TPACK into action in learning design: The case of PeerLAND

Although previous research highlights the complementary relationship of learning design with TPACK, this is not the case for TPACK informing the development of digital learning design tools. In this paper, we present PeerLAND (Peer Evaluation of LeArNingDesigns). This learning design tool interweaves design and peer evaluation in an integrated process based on TPACK, promoting teachers' roles as designers and reviewers. It adopts a modular design approach to support teachers as designers explicitly represent their design ideas starting from pedadogical content knowledge and gradually cultivating all the TPACK knowledge domains. The learning design process ends with peer evaluation where teachers use TPACK-based criteria to provide constructive feedback to peers. We report on a study conducted in a teacher education context to evaluate PeerLAND. Specifically, we investigate: (i) how student teachers' knowledge develops through the learning design process supported by PeerLAND, and (ii) how they value peer evaluation through PeerLAND. Our findings suggest that putting TPACK into action through PeerLAND developed student teachers’ knowledge in every TPACK domain, except for content knowledge. Furthermore, peer evaluation is considered advantageous to student teachers for getting timely constructive feedback and refining their designs, and several ideas for improving the peer evaluation mechanism are proposed. Implications for practice or policy: PeerLAND is an online tool supporting the development and peer evaluation of technology-enhanced learning designs allowing teachers to work together and switch roles between designers and reviewers. The learning design process in PeerLAND is a ready to use, step by step process for training teachers in technology-enhanced learning design. It provides a replicable blueprint for organising curricula.

Optimizing the Spatial Nonuniformity of Irradiance in a Large-Area LED Solar Simulator

The solar simulator has allowed all photovoltaic devices to be developed and tested under laboratory conditions. Filtered xenon arc lamps were the gold-standard source for solar simulation of small-area silicon photovoltaic devices; however, scaling these devices to illuminate large areas is neither efficient nor practical. Large-area solar simulation to meet appropriate spectral content and spatial nonuniformity of irradiance (SNI) standards has traditionally been difficult and expensive to achieve, partly due to the light sources employed. LED-based solar simulation allows a better electrical efficiency and uniformity of irradiance while meeting spectral intensity requirements with better form factors. This work details the design based on optical modeling of a scalable, large-area, LED-based, solar simulator meeting Class AAA performance standards formed for inline testing of printed solar cells. The modular design approach employed enables the illuminated area to be expanded in quanta of ~260 cm2 to any preferred illumination area. A 640 cm2 area illuminated by two adjacent PCB units has a measured total emission of 100 mW/cm2, with a SNI of 1.7% and an excellent approximation to the AM1.5G spectrum over the wavelength range of 350–1100 nm. The measured long-term temporal instability of irradiance (TIE) is &lt;0.5% for a 550-min continuous run. This work identifies the design steps and details the development and measurement of a scalable large-area LED-based solar simulator of interest to the PV testing community, and others using solar simulators.

Compact single-seed, module-based laser system on a transportable high-precision atomic gravimeter

A single-seed, module-based compact laser system is demonstrated on a transportable 87Rb-based high-precision atomic gravimeter. All the required laser frequencies for the atom interferometry are provided by free-space acousto-optic modulators (AOMs) and resonant electro-optic phase modulators (EOMs). The optical phase-locked loop between the two optical paths derived from the same laser provides an easy frequency manipulation between two laser frequencies separated by the hyperfine frequency of 6.835 GHz using an AOM and an EOM, respectively. Our scheme avoids parasite Raman transitions present in the direct EOM modulation scheme (modulating directly at the frequency of the hyperfine splitting), which have detrimental effects on the accuracy of the gravity measurements. The optical phase-locked loop also provides a convenient way for vibration compensation through the Raman lasers' phase offset. Furthermore, the modular design approach allows plug-and-play nature on each individual optic module and also increases the mechanical stability of the optical systems. We demonstrate high-precision gravity measurements with 17.8 μGal stability over 250 s averaging time and 2.5 μGal stability over 2 h averaging time.

A modularly tailored commuter ferry platform

Background: Among the challenges for implementation of Waterborne public transportation (WPT) are the difficulties in procuring efficient ferries tailored towards local requirements. Fundamental questions on the ferry’s environmental impact, speed and procurement costs linger in the public transport (PTP) mind. Objective: In this paper, a methodology for adopting a platform architecture for ferries is illustrated by a modular design approach. Methods: For this, WPT operational profiles are categorized by three route types in a structure for operational requirements including sustainability performance. Generic parameters for size and speed of WPT ferries are defined. Using these parameters as a skeletal structure, a modular commuter ferry concept is proposed as a set of basic modules. As a combination of these functionally independent modules, a ferry can be tailored to fit the operational requirements. Results: The paper proposes standard sizes for waterborne commuter craft and shows that ferries are compatible with land-based public transport in terms of energy efficiency and speed. Suitable speed ranges for mono hulls and catamarans are investigated and the idea of modular design for rational procurement is explored and illustrated for the three type routes. Conclusions: The proposed concepts can make WPT more attractive for PTPs as a sustainable option to complement the existing network.

Design and Analysis of a CPT System With Extendable Pairs of Electric Field Couplers

The demand for wireless power transfer systems at different power levels has been increasing for various applications, and this requires power converters with different capacities. This article proposes a capacitive power transfer (CPT) system that can be extended by a modularized approach with multiple electric field couplers. A dual-input dual-output (DIDO) system with four pairs of coupling plates is studied in detail, and it is found that the complicated cross coupling between the plates is a major barrier affecting the resonance and power transfer performance of the system. In this article, the effect of mutual capacitances on the system resonance is analyzed based on a general mutual coupling model of a multiple-input multiple-output electric field coupler. A decoupling circuit based on shared inductances and the corresponding compensation network are proposed and designed. The example system with a DIDO coupler is regarded as an extension by doubling the single-input single-output (SISO) couplers via appropriate double-sided compensation. A 1.5-kW CPT system with a DIDO coupler is built by paralleling two systems with SISO couplers, and the experimental results show that the output power doubles that of the system with the SISO coupler, so the effectiveness of the modular design approach is validated.

Rapid Evaluation and Response to Impacts on Critical End-Use Loads Following Natural Hazard-Driven Power Outages: A Modular and Responsive Geospatial Technology

The disparate nature of data for electric power utilities complicates the emergency recovery and response process. The reduced efficiency of response to natural hazards and disasters can extend the time that electrical service is not available for critical end-use loads, and in extreme events, leave the public without power for extended periods. This article presents a methodology for the development of a semantic data model for power systems and the integration of electrical grid topology, population, and electric distribution line reliability indices into a unified, cloud-based, serverless framework that supports power system operations in response to extreme events. An iterative and pragmatic approach to working with large and disparate datasets of different formats and types resulted in improved application runtime and efficiency, which is important to consider in real time decision-making processes during hurricanes and similar catastrophic events. This technology was developed initially for Puerto Rico, following extreme hurricane and earthquake events in 2017 and 2020, but is applicable to utilities around the world. Given the highly abstract and modular design approach, this technology is equally applicable to any geographic region and similar natural hazard events. In addition to a review of the requirements, development, and deployment of this framework, technical aspects related to application performance and response time are highlighted.