Adjacent Wires Research Articles

Analysis of Microstructure Characteristics of Overload Trace of Copper Conductor

Metallographic method is the most commonly used technique in electrical fire physical evidence identification. Firstly, the overload test samples of electrical lines were prepared in the simulated test chamber by using the simulation test method. Then, the macroscopic analysis and metallographic analysis were carried out on the overload melting marks of copper wires prepared in the early stage with the use of advanced instruments such as metallographic microscope and video microscope. The transition zone between the melt site and the substrate is not obvious, and there are many protruding weld marks of different sizes along the surface of the copper wire, and the wire diameter of the wire has obvious thickness change. The characteristic of metallographic structure is that the outer layer is eutectic, the inner layer is dendrite or dendrite coexists with eutectic, the size of the equiaxed crystal of the adjacent wire melting mark is obviously different, and some of them have more holes along the axis.

Ultra-low power and reliable magnetic based interconnects for nano-scale technologies

As technology shrinks toward nanometer scales, the delay and power consumption in logic gates reduces, while they follow an increasing trend in global interconnects. Consequently, on-chip interconnects have become a bottleneck from delay and power consumption points of view. In addition, due to reduced distance between adjacent wires in Nano-Scale technology, the effect of crosstalk noise has brought serious reliability challenges. In this paper, we propose an ultra-low power and reliable interconnect using magnetic based Driver-Receiver circuits and current mode signaling. The simulation results for 22-nm technology through comparison with the previous work shows significant superiority of the proposed interconnect considering delay, power consumption, and crosstalk robustness.

X-ray radiography of the overheating instability in underwater electrical explosions of wires

We present the measurements of the development of striation like instabilities during the electrical driven explosions of wires in a water bath. In vacuum based wire explosion experiments, such instabilities have long been known. However, in spite of intense research into the explosion of wires in liquids, the development of these instabilities has either not been observed or has been assumed to play a minor role in the parameters of the exploding wire due to the tamping of the wire's explosion. Using synchrotron based multiframe radiography, we have seen the development of platelike density structures along an exploding copper wire. Our measurements were compared to a 2D magnetohydrodynamics simulation, showing similar striation formation. These observed instabilities could affect the measurements of the conductivity of the wire material in the gas-plasma state—an important parameter in the warm dense matter community. The striations could also act as a seed for other instabilities later in time if the wire is in a dense flow of material or experiences a shock from an adjacent wire—as it would do in experiments with arrays of wires.

Synchrotron based X-ray radiography of convergent shock waves driven by underwater electrical explosion of a cylindrical wire array

We present X-ray radiography images showing the propagation of shock waves generated by electrical explosion of a cylindrical arrangement of wires in water driven by pulsed power. In previous experiments [S. N. Bland et al., Phys. Plasmas 24, 082702 (2017)], the merger of shock waves from adjacent wires has produced a highly symmetrical, cylindrical shock wave converging on the axis, where it is expected to produce a high density, strongly coupled plasma ideal for warm dense matter research. However, diagnostic limitations have meant that much of the dynamics of the system has been inferred from the position of the front of the cylindrical shock and timing/spectra of light emitted from the axis. Here, we present a synchrotron-based radiography of such experiments—providing direct quantitative measurements on the formation of the convergent shock wave, the increased density of water on the axis caused by its arrival, and its “bounce” after arrival on the axis. The obtained images are compared with two-dimensional hydrodynamic simulations, which reproduce the observed dynamics with a satisfactory agreement in density values.

Numerical investigations of the accuracy of conductivity wire-mesh sensors

The wire-mesh sensor (WMS) is a promising instrumentation for two-phase flows investigation. Since the WMS is a kind of intrusive sensor, some researchers have focused on its intrusive effects on the measurement results. However, apart from the intrusive effects, the uniform sensitive volume assumption also brings a systematic error. For a WMS, it is assumed that there is a linear relationship between the current received by the receiver wire and the void fraction within a square sensitive volume, of which the side length equals to the lateral distance between two adjacent wires. Since the complexity of the potential field, the uniform sensitive volume assumption brings a systematic error. In order to evaluate this systematic error, a cuboid with zero conductivity was introduced in 9 × 9 WMS potential field simulations. The results indicate that the systematic error caused by the uniform sensitive volume assumption increases in the wire plane axial distance. The wire diameter has little effects on the measurements. However, in view of eliminating the intrusive effects, the wire diameter should be as small as possible. The phenomena of over-shoots and cross-talk, which can be observed in experiments, were explained by the potential field simulation results. With the wire plane axial distance increase, the over-shoots and cross-talk will be exacerbated. Even though the over-shoots and cross-talk can cause a deviation for local void fraction measurements, they would not cause any systematic error for sectional average void fraction measurements in a square cross-section.

Smoke emission and temperature characteristics of the long-term overloaded wire in space

We developed an experimental payload to study the overloaded characteristics of wire insulations on board the China’s SJ-10 satellite. In 2-week microgravity experiments provided by the orbital flight, the smoke emissions of overloaded wire insulations were observed in space for the first time. Two smoke emission modes, namely the end smoke jet and the bubbling smoke jet, were identified with polyethylene insulations. The results showed that the geometry of the pyrolysis front dominated the direction and the range of the end smoke jet. The non-oxidative pyrolysis that occurred between the wire core and the insulation produced the high-temperature smoke and caused the bubbling smoke jet. The bubbling jet has a significant impact on the temperatures of adjacent wires, revealing an additional fire risk in microgravity. The effects of insulation thickness and excess current on the temperature rise were also discussed.

Novel Degradation Mechanism of a Structural Wire Rope During Its Life Cycle

High-carbon steel wire ropes are used for various high-load-bearing applications. They achieve tensile strength of the order of 2 GPa owing to a combination of fine pearlitic microstructure and work hardening during the drawing process. Despite these high strength levels, they can fail during service due to either manufacturing defects or service abuse. In this study, failure analysis of main hoist steel wire rope used in a basic oxygen furnace (BOF) was carried out. Several locations of the wire rope showed unprecedented microstructural degradation. The presence of surface martensite with transverse cracks was observed in severely abraded wires. Some locations of the rope revealed fusion of adjacent wires with increased interlamellar spacing of pearlite and formation of divorced pearlite in heat-affected and fusion zones, respectively. A significant variation in hardness across the wire rope was noted due to these in-service microstructural changes. Such macroscopic and microstructural deterioration has not been reported in open literature. Detailed failure analysis of the wire rope along with a novel theory explaining the mechanisms of such microstructural degradation is presented herein. This study confirms that the wire rope suffered premature damage due to improper lubrication during service that led to direct metal-to-metal contact, associated friction, abrasion, and fusion of wires. Excessive friction and abrasion of wires subsequently led to fatigue of some of the wires, as manifested by square or crown breaks and striation marks.

Effect of friction on the mechanical behavior of wire rope with hierarchical helical structures

The effect of friction on the mechanical behavior of wire rope with hierarchical helical structures under tensile and bending loads is studied. A typical 7×7 wire rope with an independent wire rope core is considered. It is assumed that friction only occurs between adjacent helical wires in the core strand, and between the core wire and the double-helix wires in the outer strands. Based on Love’s thin rod theory, the mechanical responses of the rope under tensile and bending loads are analyzed, as well as the contact force. The effects of the chirality of rope and the initial helix angle of the wire on the distribution of the contact force are analyzed. It is shown that the effect of the chirality on the contact force of wires and stresses in the rope is insignificant. The global stiffness of the rope can be enhanced by the friction effect. The contact force of wires changes periodically with the winding angle of the centerline around the axis of the strand. The current model provides an effective method to assess the local deformation and stresses of the wire rope with consideration of the inter-wire friction.

A novel electrical method to measure wire tensions for time projection chambers

We present a novel electrical technique to measure the tension of wires in multi-wire drift chambers. We create alternating electric fields by biasing adjacent wires on both sides of a test wire with a superposition of positive and negative DC voltages on an AC signal (VAC±VDC). The resulting oscillations of the wire will display a resonance at its natural frequency, and the corresponding change of the capacitance will lead to a measurable current. This scheme is scalable to multiple wires and therefore enables us to precisely measure the tension of a large number of wires in a short time. This technique can also be applied at cryogenic temperatures making it an attractive solution for future large time-projection chambers such as the DUNE detector. We present the concept, an example implementation and its performance in a real-world scenario and discuss the limitations of the sensitivity of the system in terms of voltage and wire length.

Risk assessment for bonding wires instantaneous touch in high density packaging

This paper studies the risk assessment method of bonding wires instantaneous touch during mechanical shock tests. Under-damping vibration motion is used to describe bonding wire’s motion state with mechanical shock loads. The influence of loop span, wire diameter and loop height on the amplitude and frequency of wire’s vibration are analysed based on the results of finite element analysis and design of experiments. The detection experiments of bonding wire’s instantaneous touch are conducted to get the vibration amplitude and vibration damping coefficient. Then, the risk assessment method is built by the analysis of simulation data and experiments data to evaluate the probability of adjacent wire’s transient touch under mechanical shock load.

Polarization-independent transparent effect in windmill-like metasurface

A windmill-like metasurface featuring a polarization-independent electromagnetically induced transparency (EIT) at microwave frequencies is numerically and experimentally demonstrated. The unit cell of the metasurface consists of four rotated identical metal wires, with a 45° angle between the adjacent wires. Destructive coupling between the resonance modes of the metal wires results in the emergence of a transparent window. By combining the metal wires with different degrees of symmetry, EIT effects in the metasurface show polarization-independent properties to incident linear and circular polarization waves. In addition, it is numerically demonstrated that the metasurface possesses a low-loss slow wave property with a group index of 125 and sensing capability based on the refractive index with a figure of merit of 8.73. Such a scheme may lead to many potential applications in areas of slow light and sensing.

Domain wall structure and interactions in 50 nm wide Cobalt nanowires

Arrays of cobalt nanowires with widths of 50 nm, thickness of 5 and 20 nm and periodicity of 70 nm were fabricated by pattern transfer from a self-assembled block copolymer film. Transverse domain walls (DWs) were imaged by magnetic force microscopy, indicating repulsive interactions between DWs of the same sign in the 20 nm thick wires. Micromagnetic simulations were used to identify the interactions in the six distinct cases of a pair of transverse DWs in adjacent wires, considering all the possible combinations of head-to-head and tail-to-tail DWs and the orientation of the core magnetization. The boundary between repulsive and attractive DW interactions is mapped out for wires as a function of thickness, width and interwire spacing.

Effect of sheath material and reaction overpressure on Ag protrusions into the TiO2 insulation coating of Bi-2212 round wire

In order to develop a high current density in coils, Bi-2212 wires must be electrically discrete in tight winding packs. It is vital to use an insulating layer that is thin, fulfils the dielectric requirements, and can survive the heat treatment whose maximum temperature reaches 890 °C in oxygen. A thin (20-30 µm) ceramic coating could be better as the insulating layer compared to alumino-silicate braided fiber insulation, which is about 150 μm thick and reacts with the Ag sheathed Bi-2212 wire during heat treatment. At present, TiO2 seems to be the most viable ceramic material for such a thin insulation because it is chemically compatible with Ag and Bi-2212 and its sintering temperature is lower than the maximum temperature used for the Bi-2212 heat treatment. However, recent tests of a large Bi-2212 coil insulated only with TiO2 showed severe electrical shorting between the wires after over pressure heat treatment (OPHT). The origin of the shorting was frequent silver protrusions into the porous TiO2 layer that electrically connected adjacent Bi-2212 wires. To understand the mechanism of this unexpected behaviour, we investigated the effect of sheath material and hydrostatic pressure on Ag protrusions. We found that Ag protrusions occur only when TiO2-insulated Ag-0.2%Mg sheathed wire (Ag(Mg) wire) undergoes OPHT at 50 bar. No Ag protrusions were observed when the TiO2-insulated Ag(Mg) wire was processed at 1 bar. The TiO2-insulated wires sheathed with pure Ag that underwent 50 bar OPHT were also free from Ag protrusions. A key finding is that the Ag protrusions from the Ag(Mg) sheath actually contain no MgO, suggesting that local depletion of MgO facilitates local, heterogeneous deformation of the sheath under hydrostatic overpressure. Our study also suggests that predensifying the Ag(Mg) wire before insulating it with TiO2 and doing the final OPHT can potentially limit Ag protrusions.

On the aerodynamic characteristics of stay cables attached with helical wires

To investigate the aerodynamic characteristics of stay cables attached with helical wires, a series of wind tunnel tests and computational fluid dynamics simulations were both carried out on the smooth and helical-wire cable models. The diameters of helical wires include 2, 3, and 4 mm, and the distances between adjacent helical wires include 200, 300, and 600 mm. Pressure taps were uniformly arranged on seven cross sections of the cable models. First, wind tunnel tests including 50 test cases were conducted to measure the wind forces and wind pressures on the cables using the forced vibration system in HD-2 wind tunnel. The effects of the helical wires on the mean and fluctuating aerodynamic forces and the correlation coefficients along the cable axis were investigated in detail based on the experimental data. Second, large Eddy simulation module incorporated in software FLUENT® was used to simulate the aerodynamic forces on the smooth and helical-wire cables. The parameters of the cable and the helical wire are similar to those used in the wind tunnel tests. The results show that helical wires can attenuate vortex shedding and reduce the wind pressure correlation along the cable axis. Within the Reynolds number range from 0.4 × 105 to 1.6 × 105, the mean drag force of the helical-wire cable is lower than the value of the smooth cable, and the correlation coefficient decreases with the increase in wind velocity. The results obtained from wind tunnel tests and computational fluid dynamics simulations agree well with each other. Furthermore, the wind velocity contour around the helical-wire cables obtained from computational fluid dynamics simulations visually indicates that the approaching flow is forced to separate at the surface of the helical wire in advance, which makes the vortex shedding disorder along the cable axis.

Development of omnidirectional A0 mode EMAT employing a concentric permanent magnet pairs with opposite polarity for plate inspection

This work presents an omnidirectional electromagnetic acoustic transducer (EMAT) for generating and receiving A0 mode of Lamb waves in plate structures. The proposed EMAT is composed of a spiral meander coil (SMC) and a new concentric permanent magnet pairs with opposite polarity (CPMP-OP) for enhancing the generation and detection of A0 mode. A finite element model was established to simulate the directions of the static magnetic field produced by the permanent magnets and the incentive process of guided waves. To verify the performance of the EMAT, several experiments were performed. Firstly, we experimentally verified that the developed EMAT could generate and receive a pure single A0 mode omnidirectionally. Then, the relationship between the frequency response characteristic of the developed EMAT and the interval l (the distance between the two adjacent annular wires of the SMC) were explored. Furthermore, the circumferential consistency of the transducer was well demonstrated. Finally, the sensing performance of the developed omnidirectional A0 mode EMAT employing a CPMP-OP was compared with that of EMAT with different structures of coils and permanent magnets. The experimental results indicated that the developed omnidirectional A0 mode EMAT employing a CPMP-OP could enhance the signals of the A0 mode.

Charged particle reflection by a planar artificially structured boundary with electrostatic plugging

A classical trajectory Monte Carlo simulation is used to investigate an artificially structured boundary for confinement and control of charged particles. The artificially structured boundary considered here incorporates a planar sequence of conducting wires, where adjacent wires carry current in opposite directions. Such a configuration creates a sequence of magnetic cusps and was studied previously [C. A. Ordonez, J. Appl. Phys. 106, 024905 (2009)]. The effect of introducing a sequence of electrodes for electrostatic plugging of the cusps is investigated. The results of the simulations are used to identify regions of parameter space in which particle losses through the cusps may be negligible in the single particle limit. A trap based on a cylindrical generalization of the artificially structured boundary presented here may lead to a method for confining non-neutral and partially neutralized plasmas along the edge, such that the bulk of a confined plasma is effectively free of externally applied electromagnetic fields.

Broadband modulation of terahertz waves through electrically driven hybrid bowtie antenna-VO2 devices

Broadband modulation of terahertz (THz) light is experimentally realized through the electrically driven metal-insulator phase transition of vanadium dioxide (VO2) in hybrid metal antenna-VO2 devices. The devices consist of VO2 active layers and bowtie antenna arrays, such that the electrically driven phase transition can be realized by applying an external voltage between adjacent metal wires extended to a large area array. The modulation depth of the terahertz light can be initially enhanced by the metal wires on top of VO2 and then improved through the addition of specific bowties in between the wires. As a result, a terahertz wave with a large beam size (~10 mm) can be modulated within the measurable spectral range (0.3–2.5 THz) with a frequency independent modulation depth as high as 0.9, and the minimum amplitude transmission down to 0.06. Moreover, the electrical switch on/off phase transition depends very much on the size of the VO2 area, indicating that smaller VO2 regions lead to higher modulation speeds and lower phase transition voltages. With the capabilities in actively tuning the beam size, modulation depth, modulation bandwidth as well as the modulation speed of THz waves, our study paves the way in implementing multifunctional components for terahertz applications.

Analysis of mechanical behaviors of internal helically wound strand wires of stranded wire helical spring

A stranded wire helical spring is a cylindrical helical spring, which is usually composed of an optional core wire and several layers of twisted external wires. The mechanical behavior of the internal helically wound strand wire is critical to determining the spring performance. Based on the previous studies of the mechanical properties of wire rope, a mathematical model to calculate the curvature of the helically wound strand wires, twist, and contact force among the adjacent wires of strand wires spring is established when the spring is subjected to axial load. The proposed kinematics is based on the assumption that there is no friction among the adjacent wires. Furthermore, a parametric study of factors influencing the curvature, twist, and contact force, such as the helix angle of spring and strand and deformation types, is committed for understanding of the mechanical characteristics of the helically wound strand wires with different geometric parameters. It is found that the curvature and twist are strongly dependent upon the two angles. Moreover, this study can provide significant reference for the design and manufacturing of the spring to control the contact force among external wires.

Hardness of crosstalk minimization in two-layer channel routing

Crosstalk minimization is one of the most important aspects of high-performance VLSI circuit design. With the advancement of fabrication technology, devices and interconnecting wires are being placed in close vicinity, and circuits are operating at higher frequencies. This results in crosstalk between adjacent wire segments. In this paper, it has been shown that the crosstalk minimization problem in the reserved two-layer Manhattan routing model is NP-complete, even if channels are free from all vertical constraints. It has also been demonstrated that it is hard to approximate the crosstalk minimization problem. Besides, the issue of minimizing bottleneck crosstalk has been introduced that is a new problem for crosstalk minimization. It has been proven that this problem is also NP-complete. It has been further shown that all these results hold even if doglegging is allowed.

On designing an efficient numerical-based forbidden pattern free crosstalk avoidance codec for reliable data transfer of NoCs

Inter-wire coupling capacitances can lead to crosstalk fault that is strongly dependent on the transition patterns appearing on the wires. These transition patterns can cause mutual influences between adjacent wires of NoCs and as a result threaten the reliability of data transfer seriously. To increase the reliability of NoCs against the crosstalk fault, Forbidden Pattern Free (FPFs) codes are used. To generate FPF codes, numerical systems are among the overhead-efficient mechanisms. The algorithms of numerical systems have direct effect on the amounts of the codec overheads including power consumption, area occupation and performance of NoCs. To find an overhead-efficient numerical system, this paper proposes an Algorithm for Generating FPF Numerical systems (AGFN). AGFN can provide a tradeoff for designers in selecting overhead-efficient FPF numerical systems. Using this algorithm, collection of Fibonacci-based and non-Fibonacci-based numerical systems can be generated. Then, using AGFN, non-Fibonacci-based FPF numerical system called Summation-based-Subtracted-Added-Penultimate (S2AP) is generated. Experimental results indicate that S2AP not only reduces the worst crosstalk effects by completely removing the Triplet Opposite Direction (TOD) transitions, but also it can significantly improve power consumption, area occupation and critical path overheads of codec with respect to the other state-of-the-art FPF codes.