Electrical Input Research Articles

Reconstituting Cu0/Cu+ synergy with heterostructured CeO2 enabling energy-efficient bipolar hydrogen generation

The establishment of electrocatalytic hydrogen (H2) production system with low energy consumption is of great significance for sustainable development. Herein, a groundbreaking achievement is presented by development of a bifunctional electrocatalyst (CeO2@Cu NRAs) on Cu foam, enabling simultaneously efficient catalysis of both hydrogen evolution reaction (HER, −0.18 VRHE at 10 mA cm−2) and furfural oxidation reaction (FFOR, 0.10 VRHE at 10 mA cm−2). The synergistic effect between Cu0 and Cu+ is investigated by density functional theory calculation, as well as the role of the heterostructured CeO2 played. Accordingly, subtle integration of such two half-reactions, the catalyst-assembled hydrogen system only requires an electrical input of 1.02 kWh per m3 of H2, which is one fifth of the energy consumed by conventional water electrolysis (5 kWh per m3 H2), signifying a compelling strategy for reducing energy consumption and improving the overall efficiency for hydrogen production.

A new type of supercontinuum generation in hexagonal lattice C6H6-core PCF with broadband and low-power pump

Most of the spectral bandwidths of previous publications are still limited by high input powers making them economically less than ideal. By using a benzene core (C6H6) photonic crystal fiber (PCF) as a new supercontinuum (SC) light source, it is possible to achieve a very large spectral broadening with hundreds of times lower peak power. Due to the change in the diameter of air holes in the first ring near the core, near-zero flattened dispersion, high nonlinearity and small attenuation can be achieved for spectral broadening. The structural geometries of two C6H6-PCFs are optimized to generate wide SC at low input energy. The SC spectrum produced in 1[Formula: see text]cm long of all dispersion fiber extends from a part of visible light to the near-infrared range at 1.3[Formula: see text][Formula: see text]m wavelength and a small pulse energy of 18[Formula: see text]pJ (or 450[Formula: see text]W of electrical input). The second PCF shows wide soliton-induced SC from 0.8 to 4.2[Formula: see text][Formula: see text]m with 71[Formula: see text]pJ pulse energy (or input power approximately 790[Formula: see text]W) at 1.5[Formula: see text][Formula: see text]m wavelength within a fiber of 12[Formula: see text]cm. The proposed structures have the potential to become a new class of microstructured optical fibers for low-cost, broad-spectrum SC generation.

Synergistic engineering of heteroatom doping and heterointerface construction in V-doped Ni(OH)2/FeOOH to boost both oxygen evolution and urea oxidation reactions

The exploitation of cost-effective and abundant non-noble metal electrocatalysts holds great significances in enhancing the efficiency of oxygen evolution reaction (OER) and/or urea oxidation reaction (UOR). Herein, we report an electrocatalyst with co-existing V-dopants and Ni(OH)2/FeOOH interfaces (referred to as A-NiFeV/NF, with “A” indicating “activated”). The electron coupling between Ni, Fe and V, analyzed through X-ray photoelectron spectroscopy, indicates that Ni and Fe both receive electrons from the V. Additionally, the Fe can also lead to a bias toward a lower valence of the Ni centers in Ni(OH)2. Further in situ Raman spectroscopy reveals that Ni2+(OH)2 inevitably undergoes transformation into amorphous Ni3+OOH during the activation process, however, the synergistic effects of V-dopants and Ni(OH)2/FeOOH interfaces keep the Ni centers mostly in a lower oxidation state of +2 even at high potential ranges. These low-valence Ni centers are proposed to be positively correlated with the optimized OER activity of the Ni-based electrocatalysts. As a result, the designed A-NiFeV/NF electrocatalyst exhibits low overpotentials of 234 and 313 mV to propel current densities of 10 and 100 mA/cm2, and a small Tafel slope of 37.8 mV/dec for OER in 1.0 M KOH. The catalyst demonstrates a stable OER activity for over 100 h at 100 mA/cm2. Additionally, it can be integrated with a solar cell to construct a solar-driven electrolytic OER device without additional electric input. Similarly, for the small molecule oxidation, UOR, only ∼1.33 and ∼1.39 V vs. RHE (RHE: reversible hydrogen electrode) are required to achieve 10 and 100 mA/cm2, respectively, in an electrolyte composed of 1.0 M KOH with 0.33 M urea.

Wireless electrical–molecular quantum signalling for cancer cell apoptosis

Quantum biological tunnelling for electron transfer is involved in controlling essential functions for life such as cellular respiration and homoeostasis. Understanding and controlling the quantum effects in biology has the potential to modulate biological functions. Here we merge wireless nano-electrochemical tools with cancer cells for control over electron transfer to trigger cancer cell death. Gold bipolar nanoelectrodes functionalized with redox-active cytochrome c and a redox mediator zinc porphyrin are developed as electric-field-stimulating bio-actuators, termed bio-nanoantennae. We show that a remote electrical input regulates electron transport between these redox molecules, which results in quantum biological tunnelling for electron transfer to trigger apoptosis in patient-derived cancer cells in a selective manner. Transcriptomics data show that the electric-field-induced bio-nanoantenna targets the cancer cells in a unique manner, representing electrically induced control of molecular signalling. The work shows the potential of quantum-based medical diagnostics and treatments.

A calibration method for bone conduction transducers using electrical input impedance

The output energy transferred from bone conduction devices (BCDs) highly depends on the impedance match between the BCDs and their loads. However, current clinical calibration methods normally ignore individual impedance differences and therefore do not accurately assess the output force of the BCDs at the subject’s stimulation position. To address this issue, this study proposes a non-invasive BCD calibration method integrating electromechanical modeling and electrical input impedance measurement. The lumped-parameter model subtly fuses the models of demagnetized electrical impedance and mechanical impedance, leading to a better description of BCD’s physical properties. Once these model parameters are determined, measurements of the electrical input impedance can be used to determine the mechanical load impedance, and further the BCD’s output force. Experiments on the Radio Ear B71 showed that this new calibration method can accurately estimate the mechanical load impedance and the output force of B71 in the frequency range of 300–2000 Hz with an average error of 0.7 and 1.0 dB, respectively. It was also found that the B71 wearing status can be monitored by measuring the electrical input impedance. In conclusion, the proposed BC calibration method provides a promising way to calibrate the output and monitor the status of the BCDs non-invasively.

Operating strategy investigation of a solid oxide electrolysis cell under large scale transient electrical inputs

The solid oxide electrolysis cell technology can be integrated with intermittent power sources such as wind to produce hydrogen by water electrolysis for electrical energy storage. However, the fluctuation of wind power may induce transient variations in the electrochemical and thermal performances of the solid oxide electrolysis cell. Applying active operation strategies helps improve the transient performances of the electrolysis cell under large-scale dynamic electrical inputs. In this study, a three-dimensional electrochemical-mass-heat coupling dynamic model of the solid oxide electrolysis cell with voltage-current curve and electrochemical impedance validation is developed to investigate the effects of different active operation strategies. The mechanism and feasibility of the fuel and air operation strategies in the current fluctuation are examined based on the electrochemical, concentration, and temperature responses. The optimized active fuel operating strategy is capable of achieving a dynamic range of 0–163 %. The effectiveness of the air operating strategy depends on the preheating temperature and flow rate of the air, and their selection requires a balance between temperature control ability and temperature gradient. Integrating the advantages of both fuel and air operation strategies, a fuel–air hybrid operating strategy is proposed to further increase the dynamic range to 0–170 %.

Dual Hardware-In-the-Loop (DHIL) platform for testing and validation of WEC subsystems

This paper presents the design process and application of a dual hardware hardware-in-the-loop (DHIL) testing platform targeting components and subsystems of wave energy conversion devices. The DHIL testing methodology combines two HIL-equipped test rigs allowing to simultaneously test components mounted on each rig and connected to the same simulation loop. The platform was therefore developed combining a HIL test rig for drivetrains with a HIL test rig for structural components.The DHIL testing platform has the capability to address multiple types of tests on critical subsystems and components within a WEC: characterization tests, for defining key performances of the equipment under test; accelerated tests, to assess qualitative and quantitative reliability features; and ultimate load testing, for survivability purposes. The overall aim of these tests is to identify weaknesses in an early design phase of device design or as a qualification activity prior the deployment of an ocean prototype. Additionally, HIL and DHIL tests can be used to assess the influence of a design update on the overall WEC model and to track failure interdependencies at a relevant scale. Finally, all of the above-mentioned activities can inform the development of a more accurate global numerical model, potentially at sub-system / critical component level, to be validated based on the test results.The definition of the test rig mechanical and electrical input specifications is dependent on the understanding of the load envelope each subsystem / component will be subject to during its lifetime. To define such envelope, a research activity modelling three different device types, three deployment sites and multiple design situations (e.g. power production, parked, shut-down etc.) led to the creation of a load database that was combined with information from WEC developers.After defining the input specifications, the rigs were designed by identifying the optimal layout, the key components and the setup of the overall test area. Analyses on mechanical, electrical and hydraulic parameters were completed to ensure the required performance of each rig could be achieved, while guaranteeing the safety during their operation.The signal processing of each rig was also analysed, with the aim of defining the minimum rig latency to allow HIL and DHIL tests to be performed. This analysis took into account the possible interface characteristics of the simulator, the sensors and the main features of the models used for real-time tests.An overview of the testing activities to be conducted within the IMPACT project will be presented in this paper. Such activities aim to de-risking the technologies at early stages and increasing their maturity through a structured process. The proposed approach has the final goal of demonstrating that the DHIL testing platform is capable to reduce capital-intensive activities, often associated with the development of large-scale prototypes, which is a critical factor for the successful development and time-to-market of a WEC.

Development, calibration, and validation of a novel gray-box energy model for residential split air conditioners

Energy models for vapor compression refrigeration in residential air conditioners have been developed through white-box, gray-box, and black-box methods in decades. However, existing white-box and gray-box models require complicated equations with detailed geometries while black-box models require substantial experimental data. This paper aims to develop and validate a simple gray-box steady-state energy model without the need for detailed geometries, which can accurately predict the cooling capacity and electrical power input based on outdoor and indoor air conditions, and supply airflow rates. First three state variables, including the evaporation and condensation temperatures, and refrigerant mass flowrate, are applied to develop the energy model and are solved by three physical equations, including the energy conservations at the evaporator and condenser, and the refrigerant volume-mass flow correlation of the compressor. Secondly, seven performance property functions related to three state variables and three physical equations are identified and calibrated by simple temperature and power measurements. Finally, field experiments are conducted on a residential air conditioner to calibrate these performance property functions and validate the developed model. The validated results reveal the model can accurately predict the cooling capacity and electrical power input, with the normalized root mean square errors of 2.3% and 0.87% respectively.

Soft magnetic thin film deformation with a bistable electropermanent magnet

Physically soft magnetic materials (PSMMs) represent an emerging class of materials that can change shape or rheology in response to an external magnetic field. However, until now, no studies have investigated using an electropermanent magnet (EPM) and magnetic repulsion to magnetically deform PSMMs. Such capabilities would enable the ability to deform PSMMs without the need for continuous electrical input and produce PSMM film deformation without an air gap, as would be required with magnetic attraction. To address this, we introduce a PSMM-EPM architecture in which the shape of a soft deformable thin film is controlled by switching between bistable on/off states of the EPM circuit. We characterized the deflection of a PSMM thin film when placed at controlled distances normal to the surface of the EPM and compared its response for cases when the EPM is in the ‘on’ and ‘off’ states. This work is the first to demonstrate a magnetically repelled soft deformable thin film that achieves two electronically-controlled modes of deformation through the on and off states of an EPM. This work has the potential to advance the development of new magneto-responsive soft materials and systems.

The influence of electric circuit parameters on NOx generation by transient spark discharge

Nitrogen fixation, production of NO and NO2 from N2 and O2 in air, has been investigated with transient spark self-pulsing DC discharges. NO production is boosted by the addition of capacitors and an inductor to the electrical circuit which drives the discharge. The quantity of NO produced per joule of electrical input energy is doubled, though the quantity of NO2 produced drops. The yield of NO is also increased because the modified circuit enables higher discharge currents to be used. NO concentrations as high as 2000 ppm were obtained with input energy densities of around 300 J per liter of input gas, whilst NO2 concentrations were around 150 ppm. This simple modification of the driving circuit may have potential for optimizing the plasma chemistry with other input gas mixtures and for scaling up nitrogen fixation from air.

An Integrated Analytics of PEM Electrolyzer and Steel Making

It is widely accepted that the hydrogen-water couple can elevate the green economy circuit if powered by renewable sources of energy. Proton-exchange membrane water electrolyzer (PEMWE) being a clean electrochemical device is expected to provide an amenable solution to the hydrogen-water nexus and act as an enabler to achieving decarbonization of the steel-making industry. In this work, we throw light on the performance of a PEMWE that feeds target hydrogen volumes to a direct iron ore reduction process. The response of the electrolyzer under the presence of a host of operational stressors and variable electricity input is delineated through a macroscale modeling framework. The techno-economics associated with specific energy consumption of the downstream steel-making pathways will be further discussed based on insights from a process cost model.

Electrowetting-driven liquid lens for ultrasound: Enabling controllable focal length and flexible beam steering

Focused ultrasound is an increasingly popular non-invasive treatment modality. Still, its fixed focal point requires an array ultrasound transducer or scanning system to cover different therapeutic scenarios. To address this limitation, we developed an electrically-controlled liquid lens that enables dynamic beam focusing and steering of the incident plane ultrasound beam. The lens was carefully optimized for low-energy attenuation and low-voltage driving. We evaluated the performance of the lens using a homemade 5.5-MHz planar transducer with a 7.5-mm aperture. Our results demonstrate that the planar ultrasound beam can be adjusted to a focused beam with a focal length from 27 mm to 32 mm within 1 s by increasing the electric input (0–60 V) to the lens. Additionally, the beam angle of the ultrasound is tunable from −5 to 5° by adjusting the charge distribution on the lens. Our design enables real-time, fast-response, on-demand changing of focal length and beam angle for a single-element planar transducer. Our study presents a promising technology for altering the ultrasound beam of a planar single-element transducer for different ultrasound applications. The development of this electrically-controlled liquid lens has the potential to enhance the efficacy of focused ultrasound treatment and improve patient outcomes.

Experimental study on acoustic-induced microbubbles fusion

Droplets/microbubbles fusion technology is a key technology for many biochemical medical applications. Here, an acoustic-controlled approach to drive microbubble fusion based on focused surface acoustic wave (FSAW) is presented. When passing through the arc-shaped channel, adjacent microbubbles will decelerate, contact, and fuse induced by the FSAWs. Due to the cooperation of the FSAW and the arc-shaped flow channel structure, the microbubbles are more easily captured and fused with the adjacent microbubbles. The effects of input voltage and pressure input parameters on the microbubble fusion are studied. Relying on electrical input parameters, microbubble fusion can be effectively achieved, providing a new idea for precise gas fuse control. The regulation of the microbubbles fusion by FSAW is revealed, showing potential in the applications of the precise control of gases on a microfluidic chip.

Levelized Cost of Storage (LCOS) for a hydrogen system

In a 100% renewable energy scenario, power generation fluctuates, requiring management and control of this generation. Storage is presented as a solution to regulate production discontinuity. In particular, seasonal storage can compensate for long-term fluctuations and serve as a necessary complement to short-term storage management. Due to the potential role of hydrogen in the decarbonization of energy production systems, this research attempts to analyse the levelized cost of storage (LCOS) of this energy carrier as a solution to long-term electricity requirements. The research focuses on the analysis of the total Power-to-Power (P2P) process cost, all factors affecting the input of electricity up to the output of electricity after the conversion of the hydrogen are considered. A transformation of the surplus electricity to hydrogen through a PEM electrolyzer is proposed in this paper. This hydrogen would be stored seasonally in salt caverns. Finally, a gas-to-energy transformation using gas turbines or fuel cells is contemplated. The analysis presents highly competitive results in terms of cost, demonstrating the system's competitiveness and potential: the turbine powered by 100% hydrogen solution appears to be more cost effective than the fuel cell solution: 0.207€/kWh and 0.284€/kWh respectively. Hydrogen storage presents itself as the most cost-effective long-term alternative in the near future, even better than pumped hydro, compressed air or batteries.

Sensor Fusion for Power Line Sensitive Monitoring and Load State Estimation.

This paper deals with a specific approach to fault detection in transformer systems using the extended Kalman filter (EKF). Specific faults are investigated in power lines where a transformer is connected and only the primary electrical quantities, input voltage, and current are measured. Faults can occur in either the primary or secondary winding of the transformer. Two EKFs are proposed for fault detection. The first EKF estimates the voltage, current, and electrical load resistance of the secondary winding using measurements of the primary winding. The model of the transformer used is known as mutual inductance. For a short circuit in the secondary winding, the observer generates a signal indicating a fault. The second EKF is designed for harmonic detection and estimates the amplitude and frequency of the primary winding voltage. This contribution focuses on mathematical methods useful for galvanic decoupled soft sensing and fault detection. Moreover, the contribution emphasizes how EKF observers play a key role in the context of sensor fusion, which is characterized by merging multiple lines of information in an accurate conceptualization of data and their reconciliation with the measurements. Simulations demonstrate the efficiency of the fault detection using EKF observers.

Efficiency assessments of a compound cooling system for low-humidity applications

Present work introduces the utilization of a concentric vertical pipe heat exchanger for indirect evaporative cooling. The device is coupled to a heat pump cooler, i.e., vapour compression cycle, as a pre-cooler and pre-dehumidifier of outdoor fresh air, to reduce the cooling load exerted on the evaporator. The proposed configuration borrows concepts from cooling tower operation, which enables the recirculation of room exhaust air, stabilizing its temperature before purging, also reducing the thermal load exerted over the condenser. An experimental analysis of the setup was performed, obtaining an average temperature drop, between intake and exhaust, of ∼ 10 °C. Against standalone configuration, this resulted in a 19%, and 29%, decrease of the cooling load, and required electrical input, respectively. Moreover, the inclusion of the indirect evaporative cooling setup reduced operation time by ∼ 40%; from 36 to ∼ 18 min per hour, resulting in long-term economic savings between 41 and 44% against stock energy consumption. Based on the surplus of energy achieved, this paper conducts a redesign and optimization of the heat exchangers. Through an inverse heat transfer approach, the device footprint can be reduced between 35.8 and 38.9% in terms of its weight, and 45.5 to 44.4% in terms of its surface area; features particularly useful when it comes to limitations in structural load capacity and/or space availability. The conducted redimensioning analysis revealed initial investment savings, between 36.2 and 39.7% of total cost, which albeit lower than operational-related savings, are still comparable when it comes to the design and operation of an air handling unit. Based on obtained results, the integration of the proposed setup does enhance the performance of the stock heat pump cooler, without increasing overall energy expenditure costs, thus is presented as an affordable, retrofittable, option for air conditioning systems operating in arid and semi-arid climates.

Efficient Fault Detection of Rotor Minor Inter-Turn Short Circuit in Induction Machines Using Wavelet Transform and Empirical Mode Decomposition.

This paper introduces a novel approach for detecting inter-turn short-circuit faults in rotor windings using wavelet transformation and empirical mode decomposition. A MATLAB/Simulink model is developed based on electrical parameters to simulate the inter-turn short circuit by adding a resistor parallel to phase "a" of the rotor. The resulting high current in the new phase indicates the presence of the short circuit. By measuring the rotor and stator three-phase currents, the fault can be detected as the currents exhibit asymmetric behavior. Fluctuations in the electromagnetic torque also occur during the fault. The wavelet transform is applied to the rotor current, revealing an effective analysis of sideband frequency components. Specifically, changes in amplitude and frequency, particularly in d7 and a7, indicate the presence of harmonics generated by the inter-turn short circuit. The simulation results demonstrate the effectiveness of wavelet transformation in analyzing these frequency components. Additionally, this study explores the use of empirical mode decomposition to detect faults in their early stages, observing substantial changes in the instantaneous amplitudes of the first three intrinsic mode functions during fault onset. The proposed technique is straightforward and reliable, making it suitable for application in wind turbines with simple electrical inputs.

Novel coding schemes for dual wavelength quantum cascade laser‐based free space optical links

AbstractDual wavelength quantum cascade lasers (DW‐QCLs) are a type of semiconductor laser that can emit two different wavelengths of light simultaneously. They are constructed using quantum cascade structures, consisting of multiple layers of semiconductor materials carefully engineered to produce the desired wavelengths of light. This research article reports the numerical simulation and evaluation of the maximum capacity of free space optical (FSO) link employing novel coding schemes for DW‐QCL‐based pulsed optical transmitters. A 48‐stage DW‐QCL emitting at 10.5 and 8.9 μm wavelengths and a Quantum‐Well based Infrared Photodetector based receiver are considered for the study. The performance of the link is analyzed under short pulse transmission from the device at both wavelengths for various scenarios. Optical pulses are obtained either at a single wavelength or two different wavelengths by proper choice of electrical input current amplitude. This feature enables the implementation of four different coding schemes. Among the various coding approaches proposed, the scheme, which operates on symbols, performs the best, providing a maximum link length of 1700m, for a BER of 10−9.

Closed-Loop FES Control of a Hybrid Exoskeleton during Sit-to-Stand Exercises: Concept and First Evaluation

Rehabilitation of paralysis caused by a stroke or a spinal cord injury remains a complex and time-consuming task. This work proposes a hybrid exoskeleton approach combining a traditional exoskeleton and functional electrical stimulation (FES) as a promising method in rehabilitation. However, hybrid exoskeletons with a closed-loop FES control strategy are functionally challenging to achieve and have not been reported often. Therefore, this study aimed to investigate a powered lower-limb exoskeleton with a closed-loop FES control for Sit-to-Stand (STS) movements. A body motion capture system was applied to record precise hip and knee trajectories of references for establishing the human model. A closed-loop control strategy with allocation factors is proposed featuring a two-layer cascaded proportional–integral–derivative (PID) controller for both FES and exoskeleton control. Experiments were performed on two participants to examine the feasibility of the hybrid exoskeleton and the closed-loop FES control. Both open- and closed-loop FES control showed the desired performance with a relatively low root-mean-squared error (max 1.3∘ in open-loop and max 4.1∘ in closed-loop) in hip and knee trajectories. Notably, the closed-loop FES control strategy can achieve the same performance with nearly 60% of the electrical power input compared to the open-loop control, which reduced muscle fatigue and improved robustness during the training. This study provides novel insights into body motion capture application and proposes a closed-loop FES control for hybrid exoskeletons.

Boolean Logic Computing Based on Neuromorphic Transistor

AbstractGeneral‐purpose computers usually use logic gate computing units based on complementary metal oxide semiconductors (CMOS). Due to the separate memory and computing units in Von Neumann architecture, data transmission requires great energy and time consumption. Developing novel neuromorphic devices and comprehensively investigating their logical computing mode are crucial to achieve high‐performance and low‐power neuromorphic computation. Here, a systematic summary of Boolean logic computing based on emerging neuromorphic transistors is presented. This summary encompasses logical operation modes, materials, device structures, and working mechanisms. The input mode of Boolean logic operation is classified into electrical input, optical input, and synergistic optical/electrical input. Besides, additional modulation strategies to construct programmable logic functions by electrical, optical, and thermal signals are also summarized. These strategies hold great significance as they enable dynamic reconfiguration of logic operations and provide neuromorphic devices with decision‐making capabilities. Finally, the application prospects and current challenges to Boolean logic computing based on dendritic integration are discussed from the aspects of device integration, synergistic input/modulation modes, auxiliary peripheral circuit, software/hardware system, etc. It is believed that comprehensive investigations on neuromorphic Boolean logic operations are crucial to push forward the development of future neuromorphic computing toward high efficiency and high integration density.