Pair Of Wires Research Articles

Design of a Robust Multi-Channel Timing Recovery System With Imperfect Channel State Information for 10GBASE-T

The interdependence among multiple channels and the interaction between timing and equalization loops bring new challenges to the design of a multi-channel symbol timing recovery (STR) system for 10GBASE-T. In addition, the nonlinear Tomlinson-Harashima precoding (THP) technique used in the 10GBASE-T system is vulnerable to the imperfect channel state information (CSI). In this paper, we address the problem of timing inaccuracy caused by imperfect CSI and the problem of extracting correct timing information in the presence of channel-interdependence and loop-interaction for 10GBASE-T. This paper proposes a novel averaged-sampling-phase (ASP) hybrid STR scheme, which aligns the sampling clock phase of a single phase-locked loop (PLL) with an average value of the timing information provided by each wire pair so that the impact of the noisy timing information resulting from the imperfect CSI and the timing jitter of the single PLL is reduced. Moreover, a three-phase timing recovery strategy based on our architecture is also designed to correctly extract the timing information and effectively mitigate the loop-interaction. Simulation results demonstrate that the proposed multi-channel STR provides a complete loop-timed solution for 10GBASE-T and achieves a superior performance over conventional approaches in terms of robustness and timing jitter.

Motor Unit Recruitment Order in Diaphragm Muscle Following Spinal Cord Injury

Motor units of the diaphragm muscle (DIAm) are recruited in an orderly fashion across ventilatory and non‐ventilatory tasks. Spinal hemisection at C2 (C2HS) blocks descending ipsilateral input to phrenic motoneurons and causes DIAm paralysis. With time after C2HS, there is spontaneous recovery of phrenic nerve activity ipsilateral to the injury. We hypothesized that recruitment order of DIAm motor units is maintained following recovery of DIAm electromyographic (EMG) activity post‐C2HS. DIAm EMG activity in adult male rats was recorded chronically using a pair of electrode wires implanted into the midcostal region bilaterally. DIAm EMG activity was strongly correlated to transdiaphragmatic pressure (Pdi) measured using esophageal and gastric balloons across different motor behaviors (Eupnea, hypoxia‐hypercapnia (10%O2 and 5%CO2), tracheal occlusion, fictive sneezing and bilateral supramaximal phrenic nerve stimulation). Fictive sneezing produced forces comparable to those elicited by phrenic nerve stimulation, and thus DIAm EMG activity during fictive sneezing was considered maximal. Absence of DIAm EMG activity was verified at the time of C2HS and 3 days (3D) post‐C2HS. Over time, a subset of animals displayed functional recovery of rhythmic DIAm EMG activity ipsilateral to C2HS, although DIAm EMG activity was reduced when compared to pre‐injury levels. EMG activity increased across ventilatory and non‐ventilatory tasks associated with increasing drive in C2HS animals displaying functional recovery, supporting a generalized strengthening of contralateral presynaptic drive over time following spinal cord injury.

A Planar Metamaterial With Dual-Band Double-Negative Response at EHF

We report the fabrication and electromagnetic characterization of a planar composite metamaterial (CMM) that is designed to achieve dual-frequency double-negative response at the lower end of the extremely high-frequency (EHF) band. The CMM is based on cut wire pairs and continuous wire elements. Dual-frequency operation is obtained by employing cut wire pairs of two different lengths within the unit cell of the CMM. The magnetic response of the cut wire pairs and the left-handed transmission band of the CMM are demonstrated by experiment and numerical simulations. It is found that the combined electric response of the dual-band CMM is complicated and imposes certain restrictions to the structure design in achieving true left-handed response at both designated frequencies.

Mitralign Percutaneous Annuloplasty System for the Treatment of Functional Mitral Regurgitation

Mitralign, Inc. (Tewksbury, MA) has developed a proprietary mitral valve repair system that attempts to mimic surgical suture annuloplasty. The Mitralign system is a set of devices approaching the posterior mitral annulus through the left ventricle. A steerable catheter is delivered via a 12.5Fr deflectable guide catheter between the papillary muscles facing the posterior annulus. The steerable catheter and a two-arm (Bident) catheter help place two pairs of wires through the annulus at the P1 and P3 locations. Each crossing wire is passed into the left atrium under transoesophageal (TEE) guidance. Once the wire pair is placed at one location, surgical pledgets are delivered over the wires and anchored across the annulus. The pledgets are pulled together to decrease the annulus circumference and the achieved plication is locked in place. Once the entire procedure is completed at one location, the next wire pair is placed at the other scallop location. TEE is an enabling imaging modality for the Mitralign procedure, which is performed with close collaboration between interventional cardiologists and echocardiologists.

A 2% Bandwidth C-Band Filter Using Cascaded Split Ring Resonators

A 2% bandpass filter with an out-of-band rejection in excess of 30 dB was demonstrated experimentally for operation in the C-band (central frequency at 4.5 GHz). Narrow bandwidth and high rejection were achieved by cascading three double split-ring resonators (SRRs) magnetically coupled to a coplanar waveguide (CPW) and three pairs of shunt wires between the central strip and the ground metal layers. This configuration, directly inspired from the so-called metamaterial technology, takes advantage of the high dispersion of the loaded transmission line, induced by a negative magnetic response via the resonators, and of a negative permittivity effect via the shunt wires. The optimization of: 1) the symmetry; 2) the out-of-band rejection; and 3) the fractional bandwidth was carried out in two stages, i.e., by engineering the plasma frequencies of the electrical and magnetic systems and by tapering the tightly coupled cascaded unit cells in order to achieve an overlap of their individual responses.

Validation of a fast scanning technique for corrosion inhibitor selection: influence of cross‐contamination on AA2024‐T3

AbstractAiming the assessment of novel, environmentally friendly corrosion inhibitors that can substitute chromate‐based ones, this work describes and validates a method for the rapid screening of water‐soluble inhibitors. The technique involves a fixed potential being applied between identical electrodes while immersed in an inhibitive solution and with the absence of a reference electrode. The current flowing between the electrodes is measured and the combined electrochemical response of the anodic and cathodic reactions, with and without the inhibitor, is then characterized. The incorporation of nine pairs of different metallic wires into a single assembly enables the effect of inhibitors on different metals to be assessed rapidly. The methodology presented allows approximately 30 electrochemical experiments to be performed per hour. In order to prove the usefulness of the proposed rapid screening technique (multielectrode), results obtained with the multielectrode are validated by comparison to the results obtained with a single electrode using only AA2024‐T3. The accuracy, reproducibility and parameter dependence has been assessed with the variation of inhibitor type and solution pH. Low absolute errors are found when studying inhibitors with good performance, giving confidence that no good inhibitors would be missed by this rapid screening method. The effect of cross‐contamination has been assessed and found to be negligible for almost all the pH range. Copyright © 2009 John Wiley & Sons, Ltd.

Negative index from asymmetric metallic cut wire pairs metamaterials

Metamaterials made of exclusively metallic cut wire pairs have been experimentally demonstrated to exhibit a negative refractive index at optical frequencies. However, other related works on slightly different wire and plate pairs have not shown a negative index. In this paper, we present the analogy between previously reported S-shaped metamaterials and asymmetric cut wire pairs by a simple unifying approach. These two structures present a negative index for some geometrical configurations. Using simulations and experimental measurements in the microwave domain, we investigate the material properties of the last structure. Applying the inversion method from transmission and reflection responses, we show that a negative index is exhibited due to simultaneous negative permittivity ε and permeability μ. A negative index n is experimentally verified in a bulk prism engineered by stacking several layers of the metamaterial.

Incidence dependence of negative index in asymmetric cut wire pairs metamaterials

Metamaterials made of asymmetric cut wire pairs have experimentally demonstrated a negative refractive index at microwave frequencies. In this letter, we begin by presenting the analogy between asymmetric cut wire pairs and S-shaped metamaterials by a simple unifying approach. Then, using simulations and experiments in the microwave domain, we investigate the dependence of resonances and retrieved effective index on the incident angle in asymmetric cut wire pairs. While it is found that resonances shift in frequency with increasing oblique incidence in the E-plane, it is shown that the structure is angle-independent in the H-plane.

Metamaterial composed of wire pairs exhibiting dual band negative refraction

The design of the metamaterial that can exhibit negative refraction at two frequency bands is presented. The components of this metamaterial are cut wire pairs and continuous wires. The cut wire pairs structure in our sample can achieve the magnetic resonance at two frequency bands by appropriately designing the cut wire dimension. Through numerical simulation, the transmission property of the proposed dual band negative index metamaterial is investigated and its result shows that with the introduction of continuous wires, the stop bands for cut wire pairs (permeability μ<0) and the frequency band for continuous wires (permittivity e<0) components would overlap and lead to the appearance of pass bands near the two magnetic resonance frequency bands. Its electromagnetic properties are then retrieved to demonstrate that the dual band left-hand behavior can be obtained in our sample structure. It is believed that our approach will be effective to make this kind of dual band negative refractive metamaterial based on the multiple magnetic resonances work at optical frequency.

Dual band directive patch antenna based on the cut wire pairs structure

AbstractIn this letter, a dual band directive patch antenna with meta‐superstrate is presented. This meta‐superstrate is composed of cut wire pairs with two different lengths, which can make this antenna work at two frequency bands. It is found that the variation of distance h between the meta‐superstrate and ground would affect the radiation performance at every frequency band. Based on the F‐P theory, we discuss this influence process and make tradeoff between the gain of the antenna at the first and second frequency. The patch antenna with meta‐superstrate is then fabricated, and the measured results show that the designed antenna works at f1 = 14.7 GHz and f2 = 15.3 GHz, where the gain of the antenna can be both improved by about 8 dB with the introduction of meta‐superstrate. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 160–163, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.24875

Coupling of gap plasmons in multi-wire waveguides

We investigate the coupling of gap plasmons in various configurations of neighboring metallic nanowires. Starting with the basic element defining a gap plasmon, consisting of two neighboring silver wires, we study the energy splitting and symmetry properties of hybridized plasmons resulting from the interaction of two wire pairs. The system is shown to display non-avoided crossings of hybridized modes, and it evolves at short distances towards a degenerate system consisting of four wires arranged in a square, where two new gap plasmons emerge from redshifted higher-energy modes. The gap modes of three neighboring wires are also described in a continuous transition from a coplanar configuration to an equilateral triangle arrangement. The interaction between wire pairs is shown to be weak enough to prevent efficient transfer of plasmon signal from a pair to the other one, which is beneficial to avoid crosstalking, but not to produce waveguide couplers. The coupling is significantly increased by placing a wire of rectangular cross section in between the wire pairs, thus allowing us to achieve large plasmon-signal transfers within propagation distances below the attenuation length. Our results can find application in the design of signal-processing devices based upon gap plasmons.

Metamaterials: Detailed parametric studies on cut-wire pair and combined structure

We studied the electromagnetic behavior of cut-wire pair structure, which is considered as a magnetic metamaterial for designing the left-handed material. It was found that the lattice constant of cut-wire pair structure provides subtle effects not only on the electric resonance but also on the magnetic one. In addition, we also investigated on how this affects the left-handed behavior of combined structures of cut-wire pair and continuous wire. These structures were designed, fabricated, and measured in the microwave frequency regime.

Design of a Bending Section Auto-Driven Mechanism for Colonoscope

Colon cancer is the second leading cause of cancer-related death in the United States. Colonoscopy is the best technology available to detect and treat abnormalities within the colon. It is a procedure that enables a gastroenterologist to evaluate the appearance of the inside of the colon by inserting a flexible tube with about 3/8 in diameter into the anus, and then advancing it slowly, under visual control, into the rectum and through the colon. This procedure is often onerous due to that the driving of the bending section (tip) of the scope and perforation may occur with the rate of 1 out of 1700 procedures. The tip driving system consists of two angulation knobs, two chain-sprocket mechanisms, a series of ring-pivot mechanism, and two pair of wires. Rotating each knob extends and retracts a pair of wires which changes the orientation of the bending section. The up/down angulation knob generates an elevation motion and the left/right angulation knob generates an azimuth motion. Based on the traditional colonoscopy, this work developed an intelligent technology to extend and enhance the diagnostic and surgical capability of the instrument. This intelligent colonoscope includes an image-based control of the tip to release a doctor from onerous work, advanced imaging systems for diagnostics, and advanced human-machine interfaces to facilitate the doctor's operation in an effective manner. In the realization of the bending section driving automation, the driving mechanism design is one of the key issues. In our design of the bending section motion control mechanism, the handle of the colonoscope and the motors are fixed on a holder. The holder can travel along a track. The track can be fixed on any flat surface such as a desk in order to enlarge the motion range of the colonoscope body. Belt mechanism is used to translate the motion from motors to the knobs. The belt pulley is fixed on the driving knob through four equally distributed screws. In order to keep the belt tied all the time, a rocker mechanism with a spring is used between the motor and the knob. Two motors are used to drive the two angulation knobs. Two limit switches are used to identify the homing position of the two motors. The driving torque is limited through the constraint of the current supplied to the motor by an amplifier to avoid the damage to the mechanical system. Together with the motion control system, the mechanism has been lab-tested using an artificial colon. It is observed that the mechanism performs well to accomplish the automation of the knob driving tasks. The system has also been tested using a pig in the animal lab of a hospital satisfactory results have been obtained.

Symmetry breaking in metallic cut wire pairs metamaterials for negative refractive index

Metamaterials made of exclusively metallic cut wire pairs have been experimentally demonstrated to exhibit a negative refractive index at optical frequencies. However, other related works have not shown a negative index. In this paper, we propose an easy way to manipulate the magnetic and electric resonances of these metamaterials to produce a negative index. We show that judiciously breaking the symmetry of the structure allows tuning of both resonances leading to an overlapping between the negative permeability and negative permittivity regions. Numerical and experimental parametric studies of several cut wire pairs metamaterials are presented to validate our method at microwave frequencies.

Composite metamaterials with dual-band magnetic resonances in the terahertz frequency regime

Composite metamaterials (CMMs) combining a subwavelength metallic hole array (i.e. one-layer fishnet structure) and an array of split-ring resonators (SRRs) on the same board are fabricated with gold films on a silicon wafer. Transmission measurements of the CMMs in the terahertz range have been performed. Dual-band magnetic resonances, namely, an LC resonance at 4.40 THz and an additional magnetic resonance at 8.64 THz originating from the antiparallel current in wire pairs in the CMMs, are observed when the electrical field polarization of the incident light is parallel to the gap of the component SRR. The numerical simulations agree well with the experimental results and further clarify the nature of the dual-band magnetic resonances.

A 256 x 256 2-D array transducer with row-column addressing for 3-D rectilinear imaging.

We present simulation and experimental results from a 5-MHz, 256 x 256 2-D (65,536 elements, 38.4 x 38.4 mm) 2-D array transducer with row-column addressing. The main benefits of this design are a reduced number of interconnects, a modified transmit/receive switching scheme with a simple diode circuit, and an ability to perform volumetric imaging of targets near the transducer with transmit beamforming in azimuth and receive beamforming in elevation. The final dimensions of the transducer were 38.4 mm x 38.4 mm x 300 microm. After a row-column transducer was prototyped, the series resonance impedance was 104 Omega at 5.4 MHz. The measured -6 dB fractional bandwidth was 53% with a center frequency of 5.3 MHz. The SNR at the transmit focus was measured to be 30 dB. At 5 MHz, the average nearest neighbor crosstalk was -25 dB. In this paper, we present 3-D images of both 5 pairs of nylon wires embedded in a clear gelatin phantom and an 8 mm diameter cylindrical anechoic cyst phantom acquired from a 256 x 256 2-D array transducer made from a 1-3 composite. We display the azimuth and elevation B-scans as well as the C-scan for each image. The cross-section of the wires is visible in the azimuth B-scan, and the long axes can be seen in the elevation B-scan and C-scans. The pair of wires with 1-mm axial separation is discernible in the elevational B-scan. When a single wire from the wire target phantom was used, the measured lateral beamwidth was 0.68 mm and 0.70 mm at 30 mm depth in transmit beamforming and receive beamforming, respectively, compared with the simulated beamwidth of 0.55 mm. The cross-section of the cyst is visible in the azimuth B-scan whereas the long axes can be seen as a rectangle in the elevation B-scan and C-scans.

Controlling plasmon hybridization for negative refraction metamaterials

The hybridization scheme of plasmon modes in cut-wire-based left-handed metamaterials is shown to critically depend on the coupling between paired cut wires. We show that an inverted hybridization scheme obtained with an asymmetric alignment of paired cut wires is the most appropriate to negative refraction. This is validated (numerically and experimentally) by the first demonstration of negative refraction in the microwave domain using only periodic ensembles of cut wires.

Anodic oxidation of polycrystalline 3C-silicon carbide thin films during MEMS operation

In this paper, we provide the first report of corrosion occurring at the anode of polycrystalline 3C-silicon carbide MEMS electrodes under high relative humidity and applied voltage. This unusual phenomenon is determined to be electrochemical in nature. Electrode pair and canary wire corrosion behavior are investigated to yield a detailed evaluation of the stability and oxidation rate during corrosion. The effects of film stress on anodic oxidation are discussed, and suggestions to prevent damage due to corrosion are presented.

Flexible carbon nanotubes electrode for neural recording

This paper demonstrates a novel flexible carbon nanotubes (CNTs) electrode array for neural recording. In this device, the CNTs electrode arrays are partially embedded into the flexible Parylene-C film using a batch microfabrication process. Through this fabrication process, the CNTs can be exposed to increase the total sensing area of an electrode. Thus, the flexible CNTs electrode of low impedance is realized. In application, the flexible CNTs electrode has been employed to record the neural signal of a crayfish nerve cord for in vitro recording. The measurements demonstrate the superior performance of the presented flexible CNTs electrode with low impedance (11.07 kΩ at 1 kHz) and high peak-to-peak amplitude action potential (about 410 μV). In addition, the signal-to-noise ratio (SNR) of the presented flexible CNTs electrode is about 257, whereas the SNR of the reference (a pair of Teflon-coated silver wires) is only 79. The simultaneous recording of the flexible CNTs electrode array is also demonstrated. Moreover, the flexible CNTs electrode has been employed to successfully record the spontaneous spikes from the crayfish nerve cord. The amplitude of the spontaneous peak-to-peak response is about 25 μV.

A rapid screening multi-electrode method for the evaluation of corrosion inhibitors

A method is described for the rapid screening of water-soluble corrosion inhibitors, which involves a fixed potential being applied between identical electrodes while immersed in an inhibitor solution. The current flowing between the electrodes is measured and the electrochemical response of the anodic and cathodic reactions, with and without the inhibitor, is then compared. The incorporation of nine pairs of metallic wires (Al, AA2024, AA7075, Fe, mild steel, SS316, Mg, Mg-AZ31 and Zn) into a single assembly enables the effect of inhibitors on different metals to be assessed rapidly. The technique is sensitive to both anodic and cathodic inhibition mechanisms and can provide information on the concentration dependency of inhibitors. This paper provides an electrochemical analysis of the method and demonstrates its application using several soluble chemical species (potassium dichromate, cerium nitrate, sodium vanadate, sodium diphosphate, sodium octanoate) on AA2024-T3 and mild steel at 10 −2 and 10 −4 M and correlates the results with those obtained by conventional potentiodynamic polarization analysis. The errors in the approach were higher for poor inhibitors, however, efficient corrosion inhibitors have decreased experimental errors, thus, ensuring that promising inhibitor candidates are not overlooked.