Electrical Domain Research Articles

Programmable photonics for coherent transceivers

AbstractThe implementation of coherent systems in communications involves the post‐processing of the optical transmitted signal after photodetection due to the need to mitigate transmission impairments. This processing is currently performed in the electrical domain using a digital signal processing device (DSP), which increases latency, and costs in the form of power consumption and additional equipment. The use of programmable photonics in coherent systems opens the door to correcting the main transmission impairments in real‐time inside the photonic chip, allowing adaptive processing through time fluctuations.

Dispersion Compensation in Optical Fiber: A Review

A cylindrical-shaped dielectric waveguide is what an optical fiber is. The core-cladding interface confines light, as electromagnetic (EM) energy, within its surface and guides light through several internal reflections if the angle of incidence is larger than the C-critical angle. Dispersion is the spreading of light pulses as they travel along a fiber, resulting in a degradation of optical signal quality. The scattering of optical signs contorts both computerized and simple transmission across optical strands. When optical fiber transmission is widely employed and some sort of digital modulation is applied, dispersion mechanisms inside the transmitted light pulses broaden as they pass through the fiber and move along the channel. The waveguide dispersion is calculated using a simple curve-fitting method. Dispersion must require compensating. Dispersion compensation techniques are essential for the successful transmission of data over optical fiber. Dispersion compensation techniques are used to reduce the effects of dispersion and improve SNR. Dispersion compensation is the process of reducing or eliminating chromatic dispersion in an optical fiber. There are two primary methods of dispersion compensation electronic and optical. In electronic dispersion compensation, the distorted signal is converted into the electrical domain, and digital signal processing techniques are used to correct the dispersion-induced distortion. While this method is effective, it adds complexity and cost to the communication system. Hence, most modern-day systems employ optical dispersion compensation, which is a more efficient and cost-effective method. Optical dispersion compensation involves using specialized optical components, such as dispersion compensating fibers (DCFs) and fiber Bragg gratings (FBGs), to adjust the different wavelengths' arrival time. DCFs are designed to have the opposite dispersion characteristics of the transmission fiber, which allows them to compensate for the dispersion as the signal passes through. FBGs are periodic structures inscribed in the fiber that reflect specific wavelengths of light, effectively delaying their arrival time and compensating for the overall dispersion.

Electromagnetic-Wave Mechanism of Formation and Propagation of Astrophysical Vortex Jets Generated in the Jumper of a Spiral Galaxy

An explanation of the mechanism of generation and acceleration of jets in outer space is given on the basis of experiments in the physics of electrical discharge. The presence of two arms in the spiral Galaxy gives grounds to assume that they have excess charges of the opposite sign. At the moment when the electric field strength between the tips of the arms becomes sufficient, an electrical breakdown occurs, which is accompanied by the movement of the current-plasma leader in the jumper between the tips of the arms. In the head part of the leader there is a flat electric domain of a strong field, which, during its inception, emits intense transverse electromagnetic waves in a direction perpendicular to the direction of the leader’s motion and to the plane of the accretion disk. The electric domain periodically appears and collapses due to the entry of neutral particles. Transverse electromagnetic waves capture charged particles from the discharge region and accelerate them in the direction of wave propagation. The crossed fields of an electromagnetic wave perform the functions of a multistage accelerator. The acceleration of the particles of the plasma produced in the discharge to relativistic energy values in the region of narrow vortex jets occurs under the action of forces caused by the components of the electromagnetic wave fields and the pressure gradient. The charged particles of a vortex jet acquire a significant rotational moment under the action of the Lorentz force. Explanations of the generation of microwave, bremsstrahlung and optical radiation from the region of the jumper between the arms of the Galaxy in the absence of electrical breakdown are also given.

Crash precipitation of nanoscale β-phase PVDF particles

• A simple approach to transform α-phase poly(vinylidene fluoride) (PVDF) to its crystalline β-phase is outlined. • The process also led to a decrease in the size of PVDF particles. • Early results from adjusting the ratio of PVDF to solvent indicate the possibility to tailor the crystalline phase of PVDF. Poly(vinylidene fluoride) exhibits coupling between the electrical and mechanical domains while in its crystalline β-phase. The electromechanical coupling effect is known as piezoelectricity, wherein a voltage is generated from a uniform stress or strain. While several techniques have been developed to crystallize PVDF in the β-phase, the processes usually produce films or fibers with few processes producing β-phase particles. The reported processes to produce particles generally require specialized equipment that is not readily available. In this work, nano-sized β-phase PVDF particles (<100 nm) are precipitated from solution using commercially available materials. The size of the particles was observed using scanning electron microscopy (SEM) and dynamic light scattering (DLS) techniques. The phase was characterized using Fourier transform infrared spectroscopy (FTIR) and powder x-ray diffraction (PXRD). These nano-sized β-phase particles have the potential to act as inclusions in composite materials to improve electrical and mechanical properties, while the method represents a potential route to control the phase and size of PVDF particles to meet specific applications.

Challenges and progress of chemical modification in piezoelectric composites and their applications

Piezoelectric materials directly convert energy between electrical and mechanical domains, and have been widely employed in electronic devices as sensors and energy harvesters. Recent research endeavors are mainly devoted to dealing with problems such as high stiffness, brittleness, toxicity, poor durability, and low piezoelectric coefficients. Among developed strategies, chemical modification captures much attention. However, the exact physical properties and direct experimental evidence of chemical modification remain elusive or controversial thus far. In this review, we discuss the recently developed piezoelectric modification strategies for piezoelectric composites and assess the effect of different chemical modification approaches on piezoelectric properties. Moreover, we outline existing challenges and new applications of piezoelectric composites.

Semiconducting electrodes for neural interfacing: a review.

In the past 50 years, the advent of electronic technology to directly interface with neural tissue has transformed the fields of medicine and biology. Devices that restore or even replace impaired bodily functions, such as deep brain stimulators and cochlear implants, have ushered in a new treatment era for previously intractable conditions. Meanwhile, electrodes for recording and stimulating neural activity have allowed researchers to unravel the vast complexities of the human nervous system. Recent advances in semiconducting materials have allowed effective interfaces between electrodes and neuronal tissue through novel devices and structures. Often these are unattainable using conventional metallic electrodes. These have translated into advances in research and treatment. The development of semiconducting materials opens new avenues in neural interfacing. This review considers this emerging class of electrodes and how it can facilitate electrical, optical, and chemical sensing and modulation with high spatial and temporal precision. Semiconducting electrodes have advanced electrically based neural interfacing technologies owing to their unique electrochemical and photo-electrochemical attributes. Key operation modalities, namely sensing and stimulation in electrical, biochemical, and optical domains, are discussed, highlighting their contrast to metallic electrodes from the application and characterization perspective.

Design of Focused Ultrasound system for non-invasive treatment of Cystic Fibrosis: a simulation study using equivalent circuit models

Cystic fibrosis (CF) is a progressive genetic disease that causes persistent lung infections and limits the ability to breathe over time. The defective gene, Cystic Fibrosis Transmembrane Conductance Regulator (CFTR), changes a protein that creates thick mucus. The mucus clogs the airways and traps bacteria leading to infections, extensive lung damage, and failure. The objective of the proposed research is to develop and utilize novel Focused Ultrasound (FU) systems to investigate muco-modulation (the ability to alter the properties of mucus) for CF. The immediate goals of the research are as follows: 1) to utilize unfocused/focused ultrasound system to observe muco-modulation in a simulation study and 2) to design and develop customized FU system to target multiple sites to modulate mucus structure/function in a targeted area, without disrupting gross tissue function. The long-term goal of this study is to produce a wearable therapeutic device for human beings that provides non-invasive therapy and to create a complete system model that spans across electrical, acoustical, and biological domains. Thus, the research aims will extend the development of disease-specific and patient-specific treatment for CF using non-invasive ultrasound vibrations. The results presented here comprise as the first step towards that realization.

Effects of 3D electrodes arrangement in a novel AC electroosmotic micropump: Numerical modeling and experimental validation.

To date, a comprehensive systematic optimization framework, capable of accurately predicting an efficient electrode geometry, is not available. Here, different geometries, including 3D step electrodes, have been designed in order to fabricate AC electroosmosis micropumps. It is essential to optimize both geometrical parameters of electrode, such as width and height of steps on each base electrode and their location in one pair, the size of each base electrode (symmetric or asymmetric), the gap of electrode pairs, and nongeometrical parameters such as fluid flow in a channel and electrical characteristics (e.g., frequency and voltage). The governing equations comprising of electric domain and fluid domain have been coupled using finite element method. The developed model was employed to investigate the effect of electrode geometric parameters on electroosmotic slip velocity and its subsequent effect on pressure and flow rate. Numerical simulation indicates that the optimal performance can be achieved using a design with varying step height and displacement, at a given voltage (2.5V) and frequency (1kHz). Finally, in order to validate the numerical simulation, the optimal microchip was fabricated using a combination of photolithography, electroplating, and a polydimethylsiloxane microchannel. Our results indicate that our micropump is capable of generating a pressure, velocity, and flow rate of 74.2Pa, 1.76mm/s, and 14.8µl/min, respectively. This result reveals that our proposed geometry outperforms the state-of-the-art micropumps previously reported in the literature by improving the fluid velocity by 32%, with 80% less electrodes per unit length, and whereas the channel length is ∼80% shorter.

Soft strain-insensitive bioelectronics featuring brittle materials.

Advancing electronics to interact with tissue necessitates meeting material constraints in electrochemical, electrical, and mechanical domains simultaneously. Clinical bioelectrodes with established electrochemical functionalities are rigid and mechanically mismatched with tissue. Whereas conductive materials with tissue-like softness and stretchability are demonstrated, when applied to electrochemically probe tissue, their performance is distorted by strain and corrosion. We devise a layered architectural composite design that couples strain-induced cracked films with a strain-isolated out-of-plane conductive pathway and in-plane nanowire networks to eliminate strain effects on device electrochemical performance. Accordingly, we developed a library of stretchable, highly conductive, and strain-insensitive bioelectrodes featuring clinically established brittle interfacial materials (iridium-oxide, gold, platinum, and carbon). We paired these bioelectrodes with different electrochemical probing methods (amperometry, voltammetry, and potentiometry) and demonstrated strain-insensitive sensing of multiple biomarkers and in vivo neuromodulation.

Morphological Ordering of the Organic Layer for High-Performance Hybrid Thermoelectrics.

Inorganic-organic hybrids, such as Te-PEDOT:PSS core/shell nanowires, have emerged as a class of promising thermoelectric materials with combined attributes of mechanical flexibility and low cost. However, the poorly understood structure-property relationship calls for further investigation for performance enhancement. Here, through precise treatments of focused electron beam irradiation and thermal annealing on individual Te-PEDOT:PSS nanowires, new, nonchemical mechanisms are introduced to specifically engineer the organic phase, and the measured results provide an unprecedented piece of evidence, confirming the dominant role of organic shell in charge transport. Paired with the Kang-Snyder model and molecular dynamics simulations, this work provides mechanistic insights in terms of heating-enabled morphological ordering of the polymer chains. The measured results show that thermal annealing on the 42 nm nanowire results in a ZT value of 0.78 at 450 K. Through leveraging the interfacial self-assembly of the organic phase to construct a high electrical conductivity domain, this work lays out a clear framework for the development of next-generation soft thermoelectrics.

Architecting Optically Controlled Phase Change Memory

Phase Change Memory (PCM) is an attractive candidate for main memory, as it offers non-volatility and zero leakage power while providing higher cell densities, longer data retention time, and higher capacity scaling compared to DRAM. In PCM, data is stored in the crystalline or amorphous state of the phase change material. The typical electrically controlled PCM (EPCM), however, suffers from longer write latency and higher write energy compared to DRAM and limited multi-level cell (MLC) capacities. These challenges limit the performance of data-intensive applications running on computing systems with EPCMs. Recently, researchers demonstrated optically controlled PCM (OPCM) cells with support for 5 bits / cell in contrast to 2 bits / cell in EPCM. These OPCM cells can be accessed directly with optical signals that are multiplexed in high-bandwidth-density silicon-photonic links. The higher MLC capacity in OPCM and the direct cell access using optical signals enable an increased read/write throughput and lower energy per access than EPCM. However, due to the direct cell access using optical signals, OPCM systems cannot be designed using conventional memory architecture. We need a complete redesign of the memory architecture that is tailored to the properties of OPCM technology. This article presents the design of a unified network and main memory system called COSMOS that combines OPCM and silicon-photonic links to achieve high memory throughput. COSMOS is composed of a hierarchical multi-banked OPCM array with novel read and write access protocols. COSMOS uses an Electrical-Optical-Electrical (E-O-E) control unit to map standard DRAM read/write commands (sent in electrical domain) from the memory controller on to optical signals that access the OPCM cells. Our evaluation of a 2.5D-integrated system containing a processor and COSMOS demonstrates 2.14 × average speedup across graph and HPC workloads compared to an EPCM system. COSMOS consumes 3.8× lower read energy-per-bit and 5.97× lower write energy-per-bit compared to EPCM. COSMOS is the first non-volatile memory that provides comparable performance and energy consumption as DDR5 in addition to increased bit density, higher area efficiency, and improved scalability.

Assessing future technological impacts of patents based on the classification algorithms in machine learning: The case of electric vehicle domain.

Identifying the technologies that will drive technological changes over the coming years is important for the optimal allocation of firms' R&D resources and the deployment of innovation strategies. The citation frequency of a patent is widely recognized as representative of the patent's value. Thus, identifying potential highly cited patents is an important goal. A number of studies have attempted to distinguish highly cited patents from others based on statistical models, but a more effective and applicable method needs to be further developed. This paper treats the prediction of later patent citations as a classification problem and proposes a novel framework based on machine learning methods. First, a indices system to identify highly cited patents is constructed using multiple factors that are believed to influence citation frequency. Second, various machine learning models are utilized to identify highly cited patents. The optimized model with the best generalization capability is selected to predict the future impacts of newly applied patents, which may be representative of emerging significant technologies. Finally, we select the electric vehicle (EV) domain as a case study to empirically test the validity of this framework. The optimized support vector machine (SVM) model performs well in identifying highly cited EV patents. Technological frontiers in the EV domain are identified, which are related to the topics of information systems, batteries, stability control, wireless charging, and vehicle operation. The good performance in prediction accuracy and generalization capability of the method proposed in this paper verifies its effectiveness and feasibility.

Downsizing the electric machines of energy-efficient electro-hydraulic drives for mobile hydraulics

The poor energy efficiency of state-of-the-art mobile hydraulics affects the carbon dioxide released into the atmosphere and the operating costs. These crucial factors require urgent improvements that can be addressed by the electrification of fluid power. This approach has already generated electro-hydraulic drives that remove flow throttling and enable energy recovery. However, the entire power managed by the actuators of conventional systems must pass through the electric machines. This characteristic is unfeasible for medium-to-high power applications since they need electric motors and electronics with high power ratings and large onboard generation of electricity. Thus, this paper applies to a hydraulic excavator’s boom the idea of splitting the power being transferred to/from the actuator between the hydraulic and electric domains (i.e., a centralized hydraulic power supply is involved). The objective is downsizing the power rating of the boom’s electric components while maintaining the high-power output of the hydraulic actuator. The results show the expected behavior of the hybrid excavator in terms of motion control, but only 57% of the boom’s peak power is now exchanged electrically. The resulting electric machine with 61% downsizing favors the system’s cost and compactness supporting the electrification process that is aligned with the low-carbon economy.

A Modeling Approach for the VIRT and Other Coupled Electronic and Magnetic Systems

Recently, a new class of magnetic component has emerged in which the electronics that connect to these components are fundamental to defining the conductive loops that comprise them. In these “coupled electronic and magnetic systems” (CEMSs), a clear partition cannot be made between the electrical and magnetic domains and this prevents the application of established modeling techniques for deriving their circuit representation. One such CEMS is the variable inverter/rectifier transformer (VIRT), which enables a transformer with fractional effective turns and a variable effective turns ratio. Previous investigations into the VIRT have invoked simplifying assumptions to synthesize a circuit representation, omitting the full details of operation such as the possibility and implications of ac currents induced on conductors that encircle the VIRT. Other fractional-turn transformers have simply assumed a circuit representation without undertaking modeling. In this work, a modeling approach is proposed which enables the circuit representation of a CEMS to be extracted directly from first principles. Two case studies are explored and the derived models are shown to match well with experiment. The proposed approach is suitable both for assessing the finer details of the VIRT, and other fractional-turn transformers, and as a framework for deriving and understanding new CEMS implementations.

Deep reinforcement learning for the optimized operation of large amounts of distributed renewable energy assets

This study utilizes machine learning and, more specifically, reinforcement learning (RL) to allow for an optimized, real-time operation of large numbers of decentral flexible assets on private household scale in the electricity domain. The potential and current obstacles of RL are demonstrated and a guide for interested practitioners is provided on how to tackle similar tasks without advanced skills in neural network programming. For the application in the energy domain it is demonstrated that state-of-the-art RL algorithms can be trained to control potentially millions of small-scale assets in private households. In detail, the applied RL algorithm outperforms common heuristic algorithms and only falls slightly short of the results provided by linear optimization, but at less than a thousandth of the simulation time. Thus, RL paves the way for aggregators of flexible energy assets to optimize profit over multiple use cases in a smart energy grid and thus also provide valuable grid services and a more sustainable operation of private energy assets.

Multi-physics modelling of quench in a superconducting magnet using bond graph

Bond graphs are widely used in the modelling of various systems. In this work, we are exploring the idea of using bond graphs to model the event of 'Quench' in a superconducting magnet. Quench is the event where a portion of the magnet turns normal, i.e. resistive. This starts Joule heating at that spot, and the stored energy of the magnet will be deposited at that point. This can lead to temperature rise and high voltage arcs. Here a bond graph model is proposed to study the electrical and thermal domain of the quench event. The model is further used to simulate the quench in a 6T superconducting solenoid magnet, and the results are compared with the results of a commercial quench solver. The results show close agreement with minor variations due to various assumptions taken in both cases. With the case successfully demonstrated, the model can be improved further to simulate more complex magnet systems and can provide a robust and fast method for quench simulation.

A Monolithic Graphene-Functionalized Microlaser for Multispecies Gas Detection.

Optical-microcavity-enhanced light-matter interaction offers a powerful tool to develop fast and precise sensing techniques, spurring applications in the detection of biochemical targets ranging from cells, nanoparticles, and large molecules. However, the intrinsic inertness of such pristine microresonators limits their spread in new fields such as gas detection. Here, a functionalized microlaser sensor is realized by depositing graphene in an erbium-doped over-modal microsphere. By using a 980nm pump, multiple laser lines excited in different mode families of the microresonator are co-generated in a single device. The interference between these splitting mode lasers produce beat notes in the electrical domain (0.2-1.1MHz) with sub-kHz accuracy, thanks to the graphene-induced intracavity backward scattering. This allows for lab-free multispecies gas identification from a mixture, and ultrasensitive gas detection down to individual molecule.

Growth and electrical properties of Yb3+ A-site doped PMNT:Yb single crystal

0.01Yb2O3-0.69 Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 (PMNT:Yb) single crystal with the size of Ø25 × 90 mm2 was successfully grown by the seed-guided Bridgman method. The electrical properties such as dielectric behavior, piezoelectric coefficient and ferroelectric properties were systematically characterized. The optimal d33 reached 2670 pC/N under the alternating current polarization conditions of 15 Hz, 14 kV/cm and 10 cycles. The crystal structure changed from the rhombohedral phase to the tetragonal phase during the growth process, and the phase transition temperature is 95 °C-100 °C, and TC is 128 °C-135 °C. Under the electric field of 20 kV/cm and frequency of 15 Hz, the coercive field EC of the crystal is 3.7 kV/cm, and the residual polarization Pr is 26.4 μC/cm2. Under alternating current polarization mode, the ferroelectric domain becomes periodically dense and regular, and the size of electric domain is uniform. In the wavelength range of 200–2000 nm, the absorption edge of PMNT:Yb crystal is 400 nm, and the wafer transmittance under unpolarized mode, direct current polarization mode and alternating current polarization mode are 41%–45%, 55%–58%, and 58%–63%, respectively. The PT-based relaxor ferroelectric crystals have great potential in the application of acoustic optical-electrical multifunctional couplers.

A generalized electromechanical coupled model of standing-wave linear ultrasonic motors and its nonlinear version

For the systematization of research on standing-wave linear ultrasonic motors (SWLUMs), this work develops a generalized electromechanical coupled model for characterizing SWLUMs. The proposed model focuses on dealing with modeling the generalized two-stage energy conversion in SWLUMs. The first-stage energy conversion is modeled by a four-terminal equivalent circuit model, which with a phase shifter and a couple of electromechanical transformers based on the electromechanical analogy method. The second-stage energy conversion is modeled by a physics-based, friction-driven system, involving contact nonlinearities between the stator and the mover. Furthermore, the effectiveness of this model and its further extension considering nonlinear vibrations of piezoelectric transducer (stator) are exemplified and discussed by a classical SWLUM with V-configuration stator, thereby indicating that the presented generalized model is valuable and pragmatic in simulating and characterizing SWLUMs both in electrical and mechanical domains.

Electrical and optical properties of Nd3+-doped rhombohedral Pb(Mg1/3Nb2/3)O3–PbTiO3 ferroelectric single crystal

Lead Magnesium Niobate Titanate 0.74 Pb(Mg1/3Nb2/3)O3-0.26PbTiO3 (0.74PMN-0.26 PT) single crystal doped with 1 mol% Nd3+ was grown by a modified Bridgman approach. Powder X-ray diffraction exhibited perovskite structure containing rhombohedral phase. The dielectric constants of various orientations with temperature were determined. We observed that the polarization process increases the crystal optical performances. The transmittance is significantly increased after poled along [011] direction. Optical properties changes were interpreted by electric domain structure. Energy band gaps were obtained by Tauc equation. Nd3+ has a strong emission transition band near 1062 nm; the long radiation lifetime of 148 μs indicates a low quenching effect. For the Nd-doped PMN-PT single crystals, their optical and electrical performances have been explored to extend the applications in medical, military and practical industrial production.