Longer Wire Length Research Articles

A novel design of window function modulated meander-line-coils EMATs for unidirectional Rayleigh waves generation and sidelobes suppression

A new design of Window Function modulated electromagnetic acoustic transducers (EMATs) to generate unidirectional Rayleigh waves is proposed. The novel EMATs, Rectangular-Window-Meander-Line-Coil EMATs (RWMLC-EMATs) and Kaiser-Window-Meander-Line-Coil EMATs (KWMLC-EMATs), contain two variable length meander line coils with a spacing of one quarter of Rayleigh waves’ wavelength; the excitation signals for these two coils have a phase difference of 900. The structure of the variable wire length determines the level of the sidelobes suppression; the structure of two meander line coils combined with the excitation signals with a phase difference of 900 determine that Rayleigh waves only propagate along one direction. RWMLC-EMATs and KWMLC-EMATs are analyzed via a wholly analytical method and are validated with experiments, which proves the feasibility of the proposed EMATs structure. In addition, the effect of the wire step and the longest wire length are investigated analytically and experimentally. Results indicate that, wire step mainly affects the suppressed level of sidelobes – a large wire step leads to a small suppressed level of sidelobes. This work can be used for Rayleigh waves EMATs design and optimization to improve their defect detection capability.

Thermal-Aware Fixed-Outline Floorplanning Using Analytical Models With Thermal-Force Modulation

High temperature or temperature nonuniformity has become a serious threat to performance and reliability of high-performance integrated circuits (ICs), which makes the thermal effect turn into a nonignorable issue in the circuit design or the physical design. In order to estimate temperature accurately, the locations of modules have to be determined in advance, which makes an efficient and effective thermal-aware floorplanning play a more important role. Hence, this article proposes a differentiable nonlinear placement model that can optimize temperature and minimize wirelength at the same time without needing to construct a congestion map. In addition, to avoid inducing longer wirelength while optimizing temperature, we propose some techniques, such as thermal-aware clustering, shrink of hot modules, or thermal-force modulation in the multilevel framework. The experimental results demonstrate that temperature and wirelength are greatly improved by our method compared to Corblivar. More importantly, our runtime is quite fast and the fixed-outline constraint can also be satisfied.

Influence of wire parameters on the formability of DP600 steel sheets during wire explosion impact forming

The acoustic pulses caused by the underwater wire explosion can be used to apply work on the surrounding medium. This work designed a set of adjustable wire explosion impact forming tooling to investigate the influence of wire parameters on the formability of DP600 steel sheets. The results obtained based on the current experimental conditions showed that a longer wire length mainly played a positive role in improving the energy utilization rate; a larger lifting height weakened the disadvantage of uneven distribution of pressure caused by the explosion of metal wire, and decreased the difference between the radial pressure and the circumferential pressure of the fractured elements, causing the limit strain pair to be closer to the equi-biaxial tensile strain path and increasing the limit dome heights of the tested specimens. Under the conditions of optimal wire length of 45 mm and lifting height of 37 mm, the limit dome heights and the major strains of the tested specimens were increased by 10% and 20%, respectively, as compared with quasi-static specimens; and the energy utilization rate was improved by 30–50% as compared with other combined wire parameters. The numerical simulation reproduced the dynamic deformation process of tested specimens and showed that the maximum effective strain rate was 1740/s, which was 106 times of that during the quasi-static hydraulic bulging process. The microstructural characteristics showed that under the action of high-speed impact load, the grain size of the tested specimen was reduced by 80%, as compared with that under quasi-static condition.

Reducing AC losses in high-temperature superconducting coated-conductor wires towards more efficient superconducting electric power applications

Since the discovery of high-temperature superconductivity, over 30 years ago, there has been great interest in utilising these materials to develop next-generation electric power applications that would replace conventional transformers, cables and motors and generators. There also exist novel technologies enabled by superconductivity, such as superconducting fault current limiters (SFCLs) and superconducting magnetic energy storage (SMES). The high current carrying capacity of high-temperature superconducting (HTS) coated-conductor wires, with zero (DC), or low (AC) losses, enables more efficient devices with smaller footprints and reduced weight. Continual advances in manufacturing techniques have resulted in the commercial availability of long lengths (km+) of high-quality wire from several manufacturers worldwide. This has improved the technological readiness level and commercial attractiveness of such devices.

MgB2 for MRI Magnets: Test Coils and Superconducting Joints Results.

Among key design and operation issues for MgB2 relevant to MRI magnets are: uniformity of current-carrying capacity over long lengths (>2 km) of wire; and reliability of a splicing technique. This paper presents experimental results of current-carrying capacities of a small test coil and joints, both made from MgB2 round wires, multifilament and monofilament (mono), manufactured by Hyper Tech Research, Inc. The test coils were wound with 95-m long unreacted, C (carbon)-doped MgB2 multifilament wire, sintered at 700°C for 90 min. The critical currents were measured in the 4.2 K-15 K and 0 T-5 T ranges. We have modified our original splicing technique, proven successful with unreacted, un-doped MgB2 multifilament wire sintered at 570°C, and applied it to splice both un-doped and C-doped mono wires sintered at 700°C. Most consistently good results were obtained using the un-doped mono wires. Also presented are results of a small joint-coil-PCS assembly of mono wire, operated in persistent mode at 50 A at >10 K.

Spool-packaging of shape memory alloy actuators: Performance model and experimental validation

Shape memory alloy (SMA) actuators in the wire form are attractive because of their simplistic architecture and electrical operation, and their manufacturability at high yields and low cost. While SMA actuators are known for their superior work density among smart materials, packaging long lengths of SMA wire needed for moderate to large motions is an ongoing technical challenge. This article investigates spooling as a packaging approach to provide more compact actuator footprints. An analytical, quasi-static model is derived to provide a foundational tool for the analysis and synthesis of spool-packaged SMA wire actuators. The model predicts motion with respect to a generalized architecture, and specifiable geometric, material, and loading parameters. The model prediction accounts for the effects of local friction loss and bending strains, and for a “binding” limitation due to accumulated friction. An experimental validation study demonstrates the model’s ability to predict actuator motion well in terms of form and magnitude with respect to load and packaging geometry. This model provides a basis for a systematic application of spooled-packaging techniques to overcome packaging limitations of SMA, positioning SMA wire actuators as a viable alternative in many applications.

Symmetric and Folded Tori Connected Torus Network

Hierarchical interconnection networks provide high performance at low cost by exploring the locality that exists in the communication patterns of massively parallel computers. A Symmetric Tori connected Torus Network (STTN) is a 2D-torus network of multiple basic modules, in which the basic modules are 2D-torus networks that are hierarchically interconnected for higher-level networks. We also fold the STTN to minimize the length of the longest wire of STTN. The folded network is called Folded Tori connected Torus Network (FTTN). In this paper, we present the architecture of the STTN and FTTN, addressing of node, routing of message, and evaluate the static network performance of STTN, FTTN, TTN, TESH, mesh, and torus networks. It is shown that both the STTN and FTTN possess several attractive features, including constant node degree, small diameter, low cost, small average distance, moderate bisection width, and high fault tolerant performance than that of other conventional and hierarchical interconnection networks. We further evaluate the longest wire length of FTTN and compare it with other networks. We found that the longest wire length of the FTTN is far lower than that of other networks considered in this paper while keeping good static network performance. It is just about (1 / 2 m th) of its rival STTN.

CASCADE: A Standard Supercell Design Methodology With Congestion-Driven Placement for Three-Dimensional Interconnect-Heavy Very Large-Scale Integrated Circuits

In this paper, CASCADE, a standard supercell-based design methodology, its supporting automated design flow, and associated design tools, are presented for 3D implementations of a class of interconnect-heavy application-specific very large-scale integrated circuits. In CASCADE, a system is first partitioned and synthesized using standard 2D design tools to a set of supercells with the same height and varying widths. With this, the 3D design is reduced to 3D supercell placement and 3D-via assignment. A congestion-driven simulated-annealing method is used to find a 3D placement of supercells to minimize the total wire length, the longest wire length, and the number of 3D vias and routing density. To efficiently estimate the routing density of a 3D grid space within the optimization loop, a simple probabilistic congestion model with an incremental congestion computation has been developed. Once the supercell placement is fixed, the problem of assigning 3D vias to accomplish minimal 2D routing densities and uniform 3D-via distribution is solved by an efficient min-cost-max-flow method. The proposed methods have been implemented and tested on a set of ISPD98 circuit benchmarks. Experimental results have shown that the proposed congestion-driven 3D supercell placement and flow-based 3D-via-assignment tools have yielded satisfactory placement with small-area, low-congestion, short-wire-length, few, and uniformly distributed 3D vias. Furthermore, an excellent correlation between routing-density estimation by our model and the actual routing performed by a commercial router has been observed. We have applied the proposed 3D design methodology, tools, and flows to tape out an over 4-million-gate low-density parity-check decoder in a three-tier 0.18- fully depleted silicon-on-insulator 3D CMOS process manufactured by MIT Lincoln Laboratory. The postlayout simulation of this DRC-clean layout design showed an about ten times improvement on the power-delay-area product compared to a 2D implementation in the same process.

Superconducting Lines for the Transmission of Large Amounts of Electrical Power Over Great Distances: Garwin–Matisoo Revisited Forty Years Later

In 1966, following a decade of discovery and development on A15 compounds, Richard Garwin and Juri Matisoo [1], two research staff members then in the IBM Research Division, submitted for publication a paper examining the prospect to employ one of the most promising of these materials, Nb3Sn, in a cable system for transmission of electricity. The scale of their proposal was truly enormous -100 GW (+/100 kV at 500 kA direct current) over a distance of 1000 km, the entire length refrigerated by liquid helium. At the time, such a cable would have been capable of carrying half the entire electric power generated in the United States, and about one-tenth today. This paper will revisit their vision in the context of the subsequent discovery of high temperature superconductivity twenty years later, and the now emerging availability of long lengths of high performance wire and tape for operation in the 20-80 K range. Whereas the scenario set by Garwin and Matisoo addressed the one-way transmission of electricity from remote coal and nuclear generation multi-plant farms to large population centers, we will extend their picture to include two-way transmission on a diurnal or longer period to take advantage of regional electricity pricing and production which has resulted from the deregulation of generation. We conclude that the advent of high temperature superconductivity substantially extends and brings closer both the technical and economic feasibility of Garwin and Matisoo's dream. However, we note, as did they, the caveat that whether it is desirable or necessary is another matter entirely. We believe this question will be decided in the affirmative as societal demands continue to increase for the clean, reliable and ecologically gentle delivery of large amounts of electric power, a need that was foreseen but not as overriding forty years ago as it is now.

Quantitative Derivation and Evaluation of Wire Length Distribution in Three-Dimensional Integrated Circuits Using Simulated Quenching

Three-dimensional (3D) integration is the most promising technology to improve IC performance by stacking some active device layers and connecting them using vertical interconnections. In this paper, in order to quantitatively evaluate the benefits of 3D IC, wire length distributions in 3D ICs are derived by adapting the simulated quenching algorithm for 3D placement and routing of specific benchmark circuits. By evaluating the wire length distribution, we can confirm that the total wire length is reduced by 26.0 and 41.3% with three and five active layers, respectively. Similarly, 38.1 and 52.0% reduction in the longest wire length with three and five active layers can be achieved.

Net Clustering Based Constructive and Iterative Improvement Approaches for Macro-Cell Placement

We propose a net clustering based RT-level macro-cell placement approaches. Static timing analysis identifies critical nets and critical primary input/output paths. Net clustering (based on shared macro-cells and net criticality) yields clusters wherein each cluster has strongly interdependent nets. The circuit is modeled as a graph in which each vertex v represents a net and each edge (v,u) a shared cell between nets v and u. The net clusters are obtained by applying a clique partitioning algorithm on the circuit graph. Two approaches to generate placements at RTL are proposed: constructive (cluster growth) approach and iterative improvement (simulated annealing) based approach. In the constructive approach, a cluster-level floorplanning is performed and a cluster ordering is obtained. The cluster ordering is used by a constructive procedure to generate the physical placement. In the case of iterative improvement based approach, a good ordering of clusters is obtained using simulated annealing. We report experimental results for five RTL datapaths implemented in 0.35 μm technology to demonstrate the efficacy of the proposed approaches. We compared the layouts produced by our approaches with those produced by Flint, an automatic floor planner in Lager IV Silicon Compiler [1]. For constructive placement approach, we obtained an average decrease of 43.4% in longest wirelength and 32.4% in total wirelength. The average area reduction is 7.3%. On the other hand, for the SA-based approach, we obtained an average decrease of 57.6% in longest wirelength and 42.2% in total wirelength. The average reduction in the bounding-box area is 12.3%. As expected, the SA-based approach yielded better optimization results, due to its ability to climb out of local minima.

Net-based force-directed macrocell placement for wirelength optimization

We propose a net-based hierarchical macrocell such that placement dictates the cell placement. The proposed approach has four phases. 1) Net clustering and net-level floorplanning phase: a weighted net dependency graph is built from the input register-transfer-level netlist. Clusters of nets are then formed by clique partitioning and a net-cluster level floorplan is obtained by simulated annealing. The floorplan defines the regions where the nets in each cluster must be routed. 2) Force-directed net phase: a force-directed net is performed which yields a coarse net-level without consideration for the cell placement. 3) Iterative net terminal and cell phase: a force-directed net and cell is performed iteratively. The terminals of a net are free to move under the influence of forces in the quest for optimal wire length. The cells with high net length cost may jump out of local minima by ignoring the rejection forces. The overlaps are reduced by employing electrostatic rejection forces. 4) Overlap removal and input/output (I/O) pin assignment phase: Overlap removal is performed by a grid-based heuristic. I/O pin assignment is performed by minimum-weight bipartite matching. Placements generated by the proposed approach are compared with those generated by Cadence Silicon Ensemble and the O-tree floorplanning algorithm. On average, the proposed approach improves both the total wire length and longest wire length by 18.9% and 28.3%, respectively, with an average penalty of 5.6% area overhead.

Distributed Sensing and Control Technology for Intelligent Civil Infrastructure Systems

Abstract: Sensing and control functions are the fundamental technologies on which many civil infrastructure control and monitoring systems are constructed. Early civil infrastructure control and monitoring systems employed a centralized computing model for sensor processing and actuator control. These systems required extensive wiring to route power, sensor, and control signals among the distributed input and output devices. Furthermore, the operation of the entire system depended on one or two computers. Abstractly, these civil infrastructure applications are a realtime data acquisition and control system. Due to the dramatic decrease in computing costs, it is now feasible to construct these real‐time systems using dozens or even hundreds of distributed processors linked with a data communication network. This allows the controllers to be located adjacent to sensors and actuators, thereby reducing the need for long lengths of multiconductor wire that is subject to noise and breakage. Also, failure of a single processor does not necessarily cause the entire system to fail. This paper introduces the reader to a technology called LonWorks for constructing distributed sensing and control systems. The LonWorks technology is essentially a data communication network that links together extremely small computers called Neurons. Particular emphasis is placed on describing the communication architecture and emphasizing how the distributed Neuron communication processors are designed to ensure a truly modular and open architecture.

On the manufacture of silver-sheathed Bi-2212 high temperature superconducting wires

High temperature superconductors (HTS) are presently being considered for a variety of defense and commercial applications. However, problems associated with low critical current density (Jc) in long length conductors still need to be addressed. It is realized that success in the fabrication of long lengths of wire and tape (up to 1 km) with optimum superconducting properties relies on improved manufacturing technologies. Unfortunately, there is no systematic study concerning the effect of processing parameters on the green properties of wires and tapes during the deformation processes. The focus of this investigation centered on silver (Ag) sheathed Bi-2212 wire forming processes and use of the two most common techniques, wire drawing and hydrostatic extrusion. Billets of 6.35 mm outside diameter were reduced separately by five different die sequences to a final diameter of 1.63 mm. Wires made by these procedures were characterized for properties such as Bi-2212 relative packing density, sheath material thickness, deformation force, elongation, drawing friction, and microstructural and mechanical properties. These results indicated that the amount of reduction per pass has a significant impact on the characteristics of non-heat treated wires and on the mechanical aspects of the wire drawing operations.

Temperature ramp dependent reaction kinetics of internal tin processed Nb3Sn wires

Multifilamentary Nb3Sn wires will be a critical component of a magnetic fusion reactor, which requires a high magnetic field for confinement of the plasma. The international effort to demonstrate the feasibility of the reactor design (International Toroidal Engineering Reactor, ITER) has very stringent requirements for the hysteresis loss and the critical current density Jc(≤ 600 mJ/cm3 and ≥700 A/mm2, respectively) of the Nb3Sn wires which are to be used for the central toroidal field coil magnet. Although short wire specimens can meet these requirements, consistently fabricating long lengths of wire meeting these specifications is not trivial. A part of this inconsistency is related to the effects of the temperature ramp rate on these critical properties. Thus, to investigate the observed ramp rate dependencies a metallurgical examination was performed. Samples of wires were subjected to two controlled temperature ramp cycles. Wire cross-sections were examined from samples removed at various stages of the two ramp cycles.

The extrusion of continuous lengths of YBa 2Cu 3O 7−x wire using hydroxypropyl methylcellulose

Wires of YBa 2Cu 3O 7−x were fabricated by extrusion using a hydroxypropyl methylcellulose (HPMC) binder. As little as 2 wt.% binder was added to an oxide prepared by a novel co-precipitation process, to produce a plastic mass which readily gave continuous extrusion of long lengths of wire in a reproducible fashion. Critical temperatures of 92 K were obtained for wires given optimum high-temperature heat treatments. Critical current densities greater than 1000 A cm -1 were measured at 77.3 K using heat treatments at around 910°C for 10 h. These transport critical current densities, measured on centimeter-long wires, were obtained with microstructures showing a relatively dense and uniform distribution of randomly oriented, small YBa 2Cu 3O 7−x grains.

Placement of the processors of a hypercube

The authors formalize the problem of minimizing the length of the longest interprocessor wire as the problem of embedding the processors of a hypercube onto a rectangular mesh, so as to minimize the length of longest wire. Where neighboring nodes of the mesh are taken as being at unit distance from one another, and where wires are constrained to be laid out as horizontal and vertical wires, the length of the wire joining nodes u and v of the mesh equals the graph-theoretic distance between u and v. The problem of minimizing delays due to interprocessor communication is then modeled as the problem of embedding the vertices of a hypercube onto the nodes of a mesh, so as to minimize dilation. Two embeddings which achieve dilations that (for large n) are within 26% of the lower bound for square meshes and within 12% for meshes with aspect ratio 2 are presented. >

Intermediate scale industrially processed Nb/sub 3/Sn(Ti) by powder metallurgy

Powder metallurgy processing of Nb/sub 3/Sn(Ti) wire was scaled up to 75-mm-diameter billets, each containing 4 kg of pressed powder composite. Prealloyed Nb-1.5-wt.% Ti powder was used for optimum high-field properties. An initial hot extrusion step provided complete consolidation and excellent integrity of the powder composite. Using the extruded bars, various single and multiple tin core billets were prepared and hydrostatically extruded to 12-mm-diameter bars. Long lengths of internal tin core wire were drawn without any breakage to less than 1 mm diameter. To evaluate the performance of long-length wires, small magnets were fabricated from these wires and tested in background fields of water-cooled Bitter magnets up to 20 T. The processing, performance, and microstructure of these small magnets are discussed. This intermediate-scale process used conventional metal-forming techniques that can be scaled to larger scale industrial processing. >

Nb-Al powder metallurgy processed multifilamentary wire

Powder metallurgy processed Nb-Al wire with overall critical current densities, J <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> , at 4.2K up to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 19T has been investigated in more detail, Kramer plots and directly measured H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c2</inf> values of samples with different heat treatments show an increase in H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c2</inf> at 4.2K up to 24.5T. Test coils, using long lengths of wire, and tested in fields up to 15T, show J <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> values equal to those of short samples. Multiple strand hydrostatic small scale extrusions were made. A number of third element additions including B, Mg, Co, Cr and Ni in fine powder form were incorporated in the P/M processing but these did not improve J <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> . ac losses were measured and used to determine J <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> at 10w fields. The high field ac losses are lower than that for any In Situ or powder processed Nb <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Sn wires.

Use of in situ wire in small magnets

A number of small solenoids have been wound from Nb <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Sn-Cu in situ wire in order to determine the suitability of these compositions for magnet construction. Magnets were wound after the wire was reacted and it was found that bending strains as large as 2% at the outer surfaee of the wire can be used with no degradation of the critical current. Calorimetric measurements of the ac losses indicate full penetration of the magnetic field into the wire above 8 Tesla. In addition it is found that losses are proportional to frequency as would be expected if the losses were hysteretic. Both the core method and an external diffusion method can be used satisfactorily for the fabrication of long lengths of wire.