Single Conductor Research Articles

Nonlinear dynamic analysis of galloping of a single iced conductor with four degrees of freedom based on curved beam theory

Based on the nonlinear strain-displacement relationship of spatial curved beam theory, a finite element model for galloping analysis of iced transmission lines is established, which involves three translational degrees of freedom (DOF) and one rotational degree of freedom for each node. Considering the aerodynamic nonlinearity and the geometric nonlinearity of large amplitude motions of the iced transmission line, the nonlinear dynamic finite element equation is presented by using the virtual work principle. The equation is transformed into the sub-space according to the mode superposition method and a time integration algorithm is also performed in the sub-space. Then, the element independence and modal convergence are researched. Finally, the influence of aerodynamic forces on structural frequency is analyzed. The numerical results show that aerodynamic forces will greatly affect the torsional frequency of the transmission line, which accurately reflects the dynamic characteristics of transmission lines. Furthermore, the galloping calculation of the transmission line has reliable accuracy by using 4-DOF (per node) elements for the iced conductor. On the other hand, the model can predict the actual galloping response of the transmission line, which is convenient for the implementation of subsequent control design.

A Precision Polyanion for High Performance Lithium-Ion Transport in Polymer Blend Electrolytes

A novel precision single ion conductor with an N-((trifluoromethyl)sulfonyl)phenylsulfonimide lithium salt covalently bound to every fifth carbon of a polyethylene backbone, p5PhTFSI-Li, was synthesized via post polymerization modification. The conversion to a trifluoromethanesulfonimide (TFSI) anion from the parent polymer bearing a phenylsulfonate anion was highly efficient (~90%) as determined by 19F-NMR analysis and corroborated through other spectroscopic methods. The bulky and flexible TFSI anion led to a reduced and observable glass transition temperature of ~199 °C and an improved thermal stability up to ~375 °C. Blending of p5PhTFSI-Li with poly(ethylene oxide) at various compositions was performed to investigate electrochemical performance and transference numbers with respect to the lithium electrode using a combination of impedance and polarization methods. At 90 °C, this system displayed high conductivity up to 2.00 X 10-4 S cm-1 and transference numbers were near unity independent of temperature, making this system highly competitive with other polyanion/polyether blend electrolytes. Investigations into the complex miscibility and phase behavior of these blends at various compositions was also probed by a combination of microscopy and differential scanning calorimetry.

Moving Beyond Heat and Beat

The synthesis of solid electrolytes is often described as the mixing of simple precursors (e.g. Li2CO3, La2O3, etc.), followed by extensive heating and regrinding to yield a single phase solid ion conductor. In this presentation we move beyond the traditional "heat and beat" approach to synthesis to a more nuanced approach more analogous to classic organic synthesis with the controlled and stepwise addition of reagents. We will show this approach produces a 500 fold increase in grain boundary conductivity of perovskite solid electrolytes and the complete synthesis of others in under 15 minutes and 200oC lower reaction temperatures. Through control of reaction energetics reaction selectivity can be enhanced offering unique opportunities to facilitate the properties of solid ion conductors.

Cyclic Carbonate-Based, Single-Ion Conducting Polymer Electrolytes for Li-Ion Batteries: Electrolyte Design

Solid polymer electrolytes (SPEs) have been the focus of study to address Li-ion battery issues including thermal runaway by mitigating the danger from volatile solvents. A single ion conductor has a high transference number which eliminates uncontrolled mass transport by immobilizing the anion to the polymer matrix. Problems with undesired side reactions and lithium dendrite growth can also be improved by providing a mechanical barrier. Unfortunately, single-ion conducting SPEs suffer from poor lithium-ion mobility and conductivity due to the immobilized nature of the anions, poor ion-pair dissociation, and the slower time scale diffusion in a polymer matrix compared to liquid electrolytes.In this study, cyclic carbonate-based polymer electrolytes were synthesized to mimic the beneficial properties of conventional carbonate-based liquid electrolytes, such as high level of ion dissociation and solid electrolyte interphase (SEI) formation. A series of copolymers were synthesized varying the structure and composition of the anionic monomer and polar cyclic carbonate containing monomer. The tertiary hydrogen on these carbonate monomers can act as a crosslinking point in free radical polymerizations or UV curing processes to provide robust mechanical properties to the SPEs at elevated temperatures. Although the inherent conductivities of the single-ion SPEs are on the order of 10-7 mS/cm, the addition of plasticizers can improve these conductivities to 0.1 mS/cm.

Quinuclidinium-piperidinium based dual hydroxide anion exchange membranes as highly conductive and stable electrolyte materials for alkaline fuel cell applications

Anion-exchange membrane fuel cells (AEMFCs) utilizing quaternary ammonium functionalized poly(arylene ether sulfone)s have been rapidly advanced in the clean energy research arena. However, it is highly desirable to integrate the benefits of quaternary ammonium cations in the polymeric membrane systems to achieve a high-power output together with substantial stabilities that significantly reduce the material costs. Herein, we report the tethering of two different quinuclidinium and piperidinium cations separated by a flexible –(CH2)4˗ spacer as a dual hydroxide conductor in the poly(arylene ether sulfone)s copolymer membrane (QP-PES) for enhancing the structural and physical properties as well as the ionic conductivities. The results proved that the tethering of dual hydroxide conductor in the PES backbone led to show maximum hydroxide conductivity of 88 mS cm−1 at 80 °C while enabling a hydrophilic/hydrophobic micro-phase separation due to the presence of flexible alkyl spacer. We also investigated the properties of a single hydroxide conductor exclusively comprising the quinuclidinium cation (Q-PES) and compared it with that of QP-PES. Interestingly, both the Q-PES and QP-PES membranes displayed superior thermal, mechanical, and dimensional stabilities. Most importantly, the QP-PES membrane demonstrated excellent alkaline stability over the period of 1000 h due to the existence of dual hydroxide conductor together with alkyl spacer units. Furthermore, the maximum power density of a H2/O2 single cell using QP-PES (92.3 mWcm−2) is higher than that of QP-PES (70.0 mWcm−2). The results provide a greater perception to design the high performance AEM materials.

Analytical Delay Model and Stability Analysis for MLGNR Interconnects

This paper analyzes the signal delay and relative stability of multilayer graphene nanoribbon (MLGNR) interconnects dependent on temperature at global lengths. A thermally aware driver interconnect load (DIL) system, constituted by equivalent single conductor (ESC) model along with mathematical equations, is proposed to convert multi-conductor transmission circuit into single transmission line of MLGNR. The temperature-dependent analytical delay model of MLGNR is evaluated and the obtained outcomes are compared with the simulated results. The analytical and simulated results are obtained at global interconnect length (2000-[Formula: see text]m) for 32[Formula: see text]nm, 22[Formula: see text]nm and 16[Formula: see text]nm nodes of technology under 200–500[Formula: see text]K temperature range of MLGNR. The simulation and analytical results reveal that the outcomes of the two models correspond well. The trend of the models shows the increase in delay with the rising temperature levels (200–500[Formula: see text]K) for three different nodes of technology. Further, relative stability analysis of MLGNR as interconnect line at three different technological nodes from 500–2000-[Formula: see text]m lengths is examined.

Unveiling the Side-Chain Effect on Ionic Conductivity of Poly(ethylene oxide)-Based Polymer-Brush Electrolytes

Polymer-brush architectures have attracted great interests in solid-state electrolytes for battery applications due to the facilitated segmental dynamics and latent capacity to fabricate single ion conductors. The effect of side chain architectures on the ionic conductivity of the polymer-brush electrolytes (PBEs), however, still requires a systematic exploration. This work describes a detailed study on the structure–property relationship between the side chain architectures and the ion-conducting behaviors of PBEs. By means of thermodynamic, spectroscopic, and electrochemical characterizations, factors of both chain length and graft density are investigated to elucidate the mechanism. Our results show that as the chain length increases, the ionic conductivity exhibits first an increase in the short amorphous range and then a drop in the long crystalline range. Moreover, investigation on graft density demonstrates that the amorphous PBEs achieve the highest ionic conductivity at a fully grafted configuration, indicating the significance of branched side chain architecture. For crystalline PBEs, proper regulation of graft density can alleviate the crystallization of the side chains and therefore increase the ionic conductivity. These results would improve our understanding of ion-conducting behaviors in PBEs and provide insights for designing advanced solid polymer electrolytes.

A Distribution Line Fault Location Estimation Algorithm Based on Electromagnetic Time-Reversal Method Calculated in the Finite Difference Time Domain

The distribution line is an important part of a power system. How to quickly eliminate faults is of great significance to improve the power supply reliability. Based on electromagnetic time-reversal (EMTR), this article proposes a fault location estimation algorithm calculated by the finite-difference time-domain (FDTD) method to solve two problems. One is the calculation efficiency of the fault current based method in the EMTR, and the other is the fault location accuracy of the EMTR-based method when the measurement device has a low sampling rate in the direct time. We first derived the FDTD updated equation of the node voltage, which is at the discontinuous point of the lossless single conductor transmission line. The algorithm obtains the fault current at any transverse branch of the distribution line through one-time simulation, which improves the calculation efficiency. Furthermore, considering the sampling rate of the transient signals, we analyzed the impact of the spectrum range of the transient signal, the interval of the guessed fault location, the length of the time-reversal window, the fault impedance, and the length of the line. The results showed that when the transient signal is measured at a high sampling rate (10 MHz), the proposed algorithm can be used to locate the fault with a minimum time-reversal window of 1 ms. When the sampling rate is as low as 100 kHz, the proposed algorithm can achieve accurate fault location estimation compared to the algorithm in the other time-domain electromagnetic transient simulation. The error of the proposed location algorithm is less than 100 m.

Hydroxyl-rich single-ion conductors enable solid hybrid polymer electrolytes with excellent compatibility for dendrite-free lithium metal batteries

Polyethylene oxide (PEO) based solid polymer electrolytes (SPEs) are promising candidates for constructing the safety and high-performance of lithium metal batteries (LMBs). However, a number of obstacles have limited its further application, such as low ionic conductivity, undesired mechanical properties, and low lithium-ion transference number (tLi+). Herein, a hydroxyl-rich single conductor polymer (lithium sulfonated polyvinyl alcohol, SPVA-Li) was introduced as a polymeric filler into PEO SPEs network via a simple and scalable solution casting method to fabricate the composite SPEs. The hydrogen bond interactions between SPVA-Li and PEO enable the polymer chains to be more disordered that effectively suppress PEO crystallization, endowing the SPVA-Li SPEs with high ionic conductivity (1.76 × 10−4 S cm−1) and tLi+ (0.59) at 60 °C. Moreover, such cross-linking structures also can significantly improve the mechanical strength and thermal stability of the SPVA-Li SPEs. These performances are all superior to the PEO SPEs. Thus, based on the composite SPEs, Li/Li symmetric cells run for 400 h without any short circuits, and the LiFePO4/Li batteries also can be stably operated for 100 cycles at 0.2 and 0.5 C rates, respectively. These merits enable the SPVA-Li SPEs to be very promising for developing high-performance LMBs.

Negative critical currents in single-channel Josephson junctions

We argue that negative critical currents arise generically in Josephson junctions formed by single channel conductors. Specifically, we theoretically study the Josephson coupling between two superconducting leads connected by a one-dimensional conductor in the Coulomb blockade regime. We show that in the clean regime the sign of the critical current alternates with the number of electrons in the normal region. For odd occupancy the critical current is negative even when the number of electrons on the conductor is large.

Adaptive Biosensing and Neuromorphic Classification Based on an Ambipolar Organic Mixed Ionic-Electronic Conductor.

Organic mixed ionic-electronic conductors (OMIECs) are central to bioelectronic applications such as biosensors, health-monitoring devices, and neural interfaces, and have facilitated efficient next-generation brain-inspired computing and biohybrid systems. Despite these examples, smart and adaptive circuits that can locally process and optimize biosignals have not yet been realized. Here, a tunable sensing circuit is shown that can locally modulate biologically relevant signals like electromyograms (EMGs) and electrocardiograms (ECGs), that is based on a complementary logic inverter combined with a neuromorphic memory element, and that is constructed from a single polymer mixed conductor. It is demonstrated that a small neuromorphic array based on this material effects high classification accuracy in heartbeat anomaly detection. This high-performance material allows for straightforward monolithic integration, which reduces fabrication complexity while also achieving high on/off ratios with excellent ambient p- and n-type stability in transistor performance. This material opens a route toward simple and straightforward fabrication and integration of more sophisticated adaptive circuits for future smart bioelectronics.

Toward High-Voltage Solid-State Li-Metal Batteries with Double-Layer Polymer Electrolytes

Solid polymer electrolyte batteries with a Li-metal anode and high-voltage active materials hold promising prospects to increase the energy density and improve the safety of conventional Li-ion batteries. An adequate choice of the polymers used for the cathode (catholyte) and for the separator (electrolyte) to create a sufficient energy gap and improve the chemical compatibility at both the positive electrode and Li-metal anode is required. The present work highlights the advantages of the double-layer polymer electrolyte approach in cells with a LiNixMnyCozO2 active material, a poly(propylene carbonate) (PPC) catholyte, and a poly(ethylene oxide) (PEO) electrolyte. Replacing PEO in the catholyte with PPC results in a remarkably improved cycling performance. In addition, the higher lithium transference number of electrolytes with single lithium ion conductors leads to a smooth cycling of solid-state batteries. Cells with 1 mAh cm–2 deliver 160 mAh g–1, with a capacity retention above 80% over 80 cycles and a Coulombic efficiency close to 100%.

Topology crafting of polyvinylidene difluoride electrolyte creates ultra-long cycling high-voltage lithium metal solid-state batteries

Solid-state polymer electrolytes (SPEs) present poor anti-oxidation ability, low ionic conductivity and high flammability, which greatly restrict their applications in high-voltage solid-state lithium metal batteries. Herein, we uniformly graft the lithium phenyl phosphate (LPPO) on polyvinylidene difluoride (PVDF) by dehydrofluorination and Friedel-Crafts alkylation reactions to create a multifunctional PVDF-LPPO SPE with branched topology. The LPPO serves as a single ion conductor, flame retardant and cathode electrolyte interface formation agent not only greatly improves the ionic conductivity, fireproof property and electrochemical stability of SPE, but also remarkably suppresses the side reactions with both cathode and lithium metal anode. An additional and uniform Li-ion transmission path is constructed by LPPO to remarkably reduce the activation energy and enhance the lithium-ion transference number of PVDF-LPPO SPE. The solid-state LiNi0.8Co0.1Mn0.1O2||PVDF-LPPO||Li batteries stably cycle for 1550 times between 2.8 and 4.3 V at 1 C and 1000 times under a high charging voltage of 4.5 V. The transformation of layered structure to rock-salt phase of NCM811 particles is greatly suppressed during long cycling by a stable and uniform LPPO derived cathode electrolyte interface. This work provides a precise operation method for modifying structure of polymer electrolyte to achieve outstanding special properties of lithium metal solid-state batteries.

Multiconductor Transmission Lines for Orbital Angular Momentum (OAM) Communication Links

In this article, the orbital angular momentum (OAM) mode system, known from antenna communication, is applied and extended to various multiconductor transmission lines. In the context of this work, an OAM mode describes the excitation of a multiport system with a voltage distribution that is an eigenmode of a cyclic system. The OAM mode system is the complete system composed of all <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> OAM modes for a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> -port system. For two conductors, the OAM mode system is shown to be equivalent to the differential- and common-mode systems. A transmission line carrying OAM modes must be used as a feed line in OAM communication links and, because of the orthogonality of the modes, it can be used to transmit multiple signals without mode conversion. An OAM communication link is defined in the context of this work as the components used from mode excitation of the transmitter to mode decomposition of the receiver. Using the analogy of OAM communication with antenna arrays and transmission-line theory, the excitation, geometry, characteristic mode impedance, mode power, and matching of a transmission line carrying OAM modes are derived. The matching is implemented with a mode decomposition and mode matching network on both sides of the transmission line. The performance of the system is verified numerically, with a 2-D boundary element method (BEM) solver based on the method of moments. Implementations of the OAM mode system for multiconductor cables, microstrip lines, and striplines are examined. In addition, the behavior of the mode transmission if the OAM modes are mismatched is evaluated and compared to a single conductor transmission line.

Quasi-Analytical Calculation of Frequency-Dependent Resistance of Rectangular Conductors Considering the Edge Effect

This paper presents an accurate quasi-analytical approximation of frequency-dependent ac resistance of single rectangular conductors. In this work, first, a two-dimensional analytical ac resistance of rectangular conductors is derived. Unlike circular conductors, where current density distributes evenly in each layer of the conductor’s cross-section, the edge effect is involved for rectangular conductors. Due to the edge effect, one cannot define an accurate boundary condition for solving the two-dimensional partial differential equation of magnetic field or current density of rectangular conductors. Hence, the calculated two-dimensional analytical current density result is not accurate and is modified and fitted on FEM simulation, taking the conductor’s thickness into account using the least-square problem to improve its accuracy. Unlike numerical approaches, the proposed method yields an easy-to-use formula applicable to industrial applications in different fields. Contrary to the one-dimensional approach, which is only valid for very thin rectangular conductors, this method takes edge effect into account and can be used for any thickness (from square to very thin rectangular conductors). The proposed method can be used in applications where an accurate ac resistance of rectangular conductors over a wide frequency range is required, such as white-box modeling of power transformers and interpreting its frequency response analysis (FRA), and calculating the resistance of electric machine winding, busbars, and printed circuit board traces.

Investigating miscibility and lithium ion transport in blends of poly(ethylene oxide) with a polyanion containing precisely-spaced delocalized charges

Synthesis of a precision single ion conductor with a phenylsulfonyl (TFSI) lithium salt pendant at every 5th carbon is reported and miscibility, conductivity, and transference studies are performed upon blending with PEO at varying compositions.

Magnetic coupling and spin ordering in bisdithiazolyl, thiaselenazolyl, and bisdiselenazolyl molecular materials.

The use of purely organic materials is a promising approach for the miniaturization of devices due to their interesting optical, electronic and magnetic properties. Bisdithiazolyl-based bisDTA compounds have emerged as promising candidates for radical-based single component conductors exhibiting simultaneously magnetic properties. Our computational work focuses on the intriguing magnetism of 4 isostructural pyridine-bridged bisDTA-multifunctional materials triggered by their magnetic and conducting properties being strongly dependent on the different S/Se ratios in the neutral radical skeleton: specifically, bisdithiazolyl (S,S) displays no magnetic order at low temperatures, thiaselenazolyl (Se,S) exhibits spin-canted antiferromagnetism (AFM), and both (S,Se) and bisdiselenazolyl (Se,Se) behave as bulk ferromagnets (FM). Our results reveal that (1) the magnetic response depends on the existence of an intricate network of both AFM and FM spin exchange JAB couplings between neighbouring radicals; and (2) the structural arrangement of π-stacked pairs of radicals sits on a point in the configurational space that is very close to a crossover region where JAB switches from AFM to FM. Indeed, for bulk FM, the experimental response is only accounted for when considering an ab initio optimised crystal structure able to portray adequately the electronic structure of bisDTAs in the region close to the temperature at which magnetic ordering emerges. Magneto-structural correlation maps show the large sensitivity of JAB to very small structural changes with temperature along the π-stacks that lead to drastic changes in the magnetic properties. Clearly, the understanding of magnetism in the title bisDTA compounds is decisive to rationally tailor the properties of multifunctional materials by subtle structural modifications of their crystal packing.

CFD Analysis of Fluid-Dynamic and Heat Transfer Effects Generated by a Fixed Electricity Transmission Line Interacting with an External Wind

The flow past a fixed single transmission conductor and the related heat transfer characteristics are investigated using computational fluid dynamics and a relevant turbulence model. After validating the method through comparison with relevant results in the literature, this thermofluid-dynamic problem is addressed considering different working conditions. It is shown that the resistance coefficient depends on the Reynolds number. As expected, the Nusselt number is also affected by Reynolds number. In particular, the Nusselt number under constant heat flux is always greater than that under a constant wall temperature.

Calculation Method for Dynamic Stiffness of Multispan Overhead Transmission Lines

The dynamic motion of a span is coupled to the other spans in transmission lines. From the continuity conditions, force equilibrium conditions, and dynamical equations of every span conductor and insulator string, a close-form expression for the dynamic stiffness of a coupled two spans in harmonic motion is presented. Unlike some existing theories of single span conductor, the effect between the conductors and insulator strings is considered here. By means of example calculations, the validity of the dynamic stiffness of two-span is demonstrated by the consistency of the results determined by the ABAQUS. Meanwhile, the dynamic stiffness and natural frequency are discussed under variation of the span lengths ratio, Irvine parameter, and insulator string length. Moreover, the modal shape function corresponding natural frequency is derived, and the contribution of localization mode is studied. The results show that the contribution is either sensitive to or independent of transmission line parameters in certain parameter ranges. Finally, generalizing the work of two-span, the dynamic stiffness of arbitrary span number is obtained.

Modeling and Analysis of Cu-Carbon Nanotube Composites for Sub-Threshold Interconnects

The sub-threshold regime is suited for applications requiring ultra-low power consumption with low to medium frequency (tens to hundreds of MHz) of operation. Therefore, this paper presents electrical modeling and comprehensive analysis of copper-carbon nanotube (Cu-CNT) composite interconnects for sub-threshold circuit design. At lower operating frequencies, the effective complex conductivity of Cu-CNT composites in the nanoscale is formulated by developing an analytical model. Based on the proposed equivalent single conductor model, the frequency-dependent resistance and inductance of composite interconnects are computed. Finally, the sub-threshold crosstalk effect, transfer gain, and Nyquist stability of coupled Cu-CNT composite interconnect are analyzed using <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ABCD</i> matrix approach.