Coaxial Wire Research Articles

Preparation and study of Al2O3@PPy@rGO composites with microwave absorption properties

Abstract In this work, Al2O3@PPy@rGO composites were successfully synthesized by a “coating-coating” route. The structure of Al2O3@PPy@rGO composites was characterized by XRD, Raman and SEM. The coaxial wire method was used to measure the electromagnetic properties of Al2O3@PPy@rGO composites, which was carried on the vector network analyzer (VNA, 3672A/B/C-S) over the 2–18 GHz frequency range. Compared with Al2O3 (about 50 nm), the particle size of Al2O3@PPy composites (about 70 nm) enhanced, which verified the alumina was coated by PPy. In addition, the Al2O3@PPy composites are tightly attached by the rGO with a diameter of about 30 nm Al2O3@PPy@rGO composites have excellent thermal stability, and they remain 53 wt% when the temperature is up to 800 °C. When the thickness of Al2O3@PPy@rGO composites is 3.0 mm, they reach the maximum reflection loss of −39.7 dB at 13.2 GHz with 15 wt% Al2O3@PPy@rGO-wax. And the broad effective microwave absorption bandwidth of Al2O3@PPy@rGO composites is 5.5 GHz in 10.5–16.0 GHz. In addition, the electromagnetic wave absorption mechanism of Al2O3@PPy@rGO composites was analyzed.

Equipment and process windows for laser metal deposition with coaxial wire feeding

For some materials and applications, it is advantageous to use a wire instead of powder additives for laser metal deposition (LMD). By utilizing a wire as an additive material, major disadvantages of powder-based LMD processes can be eliminated. Contamination of the process cell with metal powder, significant material losses during the process, health and safety issues, and insufficient powder quality are just some of the problems avoided by this approach. A continuous ring-shaped laser beam surrounding the wire is one of the distinguishing features of the presented LMD processing head. The laser beam and wire are arranged coaxially to each other, with the wire being fed through the inside of the hollow, ring-shaped laser beam. The coaxial supply of inert gas avoids exposure of the melt pool to atmospheric oxygen. Through this design, the wire LMD process is independent of the feed direction. A very high degree of material utilization paired with the aforementioned advantages promises the potential for efficient and precise buildup of two- and three-dimensional geometries. The reduced mass of the head through advanced design makes highly dynamic LMD processes feasible. By allowing the use of thin additive wires, even intricate geometries can be built up in near-net-shape. To evaluate the potential of this novel approach for wire-based laser material deposition, a prototype processing head was designed, built, and tested. First, results and measurements regarding beam shaping, process behavior, and resulting deposits are shown and discussed. Material samples from both Inconel 718 and Titanium Ti-6Al-4V were built and evaluated metallographically. An outlook toward future research and possible applications is given.

Combinations of tunneling and spin-orbit interaction effects on the thermodynamics and entropy of coaxial quantum wires

Thermodynamical properties of a typical coaxial quantum wire under the simultaneous effects of external electric and magnetic fields with great attention to the spin-orbit interaction and tunneling effects are investigated. To this aim the Schrodinger equation is solved to find the energy eigenvalues and eigenfunctions of the system and the Tsallis formalism is used to find thermodynamical parameters such as entropy, internal energy, and specific heat. Results show the considerable effect of the spin-orbit interaction and external fields on the electronic and thermodynamics of the presented complex system. It is shown that the tunneling phenomenon has considerable and interesting effects on the energies and entropy in comparison with mono-layer quantum wires without tunneling effects.

Survival rate of two orthodontic bonded retainer wires

We read the article “Clinical effectiveness of two orthodontic retainer wires on mandibular arch retention” (Gunay F, Oz A. Am J Orthod Dentofacial Orthop 2018; 153:232-8) with great interest. We congratulate the authors for conducting a robust study with an effective study design on this important topic. However, we would seek certain clarifications from the authors on several points:1.In paragraph 1 of the statistical analysis section, the authors mention that lingual retainer survival rates over 12 months were evaluated by means of the Kaplan-Meier test and that differences in retainer survival curves by retainer wire type were evaluated by means of the log-rank test. In Fig 3, the authors draw a Kaplan-Meier curve depicting the cumulative survival rates of group 1 (0.0175-inch 6-stranded stainless steel retainer wire) and group 2 0.0195-inch dead-soft coaxial retainer wire), but the graph touches zero percent in both groups over a 12-month follow-up period. This means that survival or success of the bonded retainer is 0% at the end of 12 months in both groups, although it is 86.8% in group 1 and 81.1% in group 2 according to Table II (log-rank test: χ2 = 0.661; P = 0.416). Figure 3 and Table II completely contradict each other. We think that the graph should be drawn as shown in Figure (Corrected).1Egli F. Bovali E. Kiliaridis S. Cornelis M.A. Indirect vs direct bonding of mandibular fixed retainers in orthodontic patients: comparison of retainer failures and posttreatment stability. A 2-year follow-up of a single-center randomized controlled trial.Am J Orthod Dentofacial Orthop. 2017; 151: 15-27Abstract Full Text Full Text PDF PubMed Scopus (27) Google Scholar, 2Dawson B. Trapp R.G. Research question about means in three or more groups.in: Dawson B. Trapp R.G. Basic and clinical biostatistics. 4th ed. McGraw Hill, New York2004: 163-189Google Scholar2.The authors applied repeated-measures analysis of variance (ANOVA) for irregularity measurements and intercanine distance. Intragroup comparison at different time points is mentioned, but what is the intergroup difference at different time points of the above parameters? In Tables IV and V, 2 different F-values are mentioned, and it seems that the authors have applied 1-way repeated-measures ANOVA separately for each treatment group and not repeated-measures ANOVA for both groups together. Our question is why intergroup repeated-measures ANOVA2Dawson B. Trapp R.G. Research question about means in three or more groups.in: Dawson B. Trapp R.G. Basic and clinical biostatistics. 4th ed. McGraw Hill, New York2004: 163-189Google Scholar was not applied.3.Intergroup comparison (Table VI) of mean irregularity measurement (mm) difference between post-treatment and 12-month retention period (T5-T1) via Mann-Whitney test gives us vital information that mandibular arch irregularity is significantly higher in group 2 than in group I. Similarly, it would also be pertinent to know the results of a Mann-Whitney test for the difference in mean intercanine distance between the 2 groups. This result may help us in localizing the irregularity site so that adequate stress can be given to the areas requiring maximum retention. The authors should comment on why this relevant information was not shared. We emphasize that by no means are we disregarding the efforts of the authors in conducting this trial, but our intention is that correct and relevant information should reach the readers of this journal. Clinical effectiveness of 2 orthodontic retainer wires on mandibular arch retentionAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 153Issue 2PreviewThe aim of this study was to evaluate and compare the clinical success of 2 lingual retainer wires. Full-Text PDF Author's responseAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 155Issue 1PreviewThank you so much for your interest and the valuable contributions you have made to our work. Full-Text PDF

Coaxial Laser Wire Deposition

The new coaxial fine wire deposition optic presents reduced weight (∼10 kg without fiber and wire feed) and has extended functionality. The optical components are designed for wavelengths of 450 – 550 nm and 890 – 1100 nm. The head is prepared for the processing of even thin wires down to 100 μm in diameter. The new system is equipped with an integrated mini camera, sensors and interfaces to control units and networks. As a result the new head exhibits potential to produce very precise metallic structures as low as 200 - 300 μm. Suitable materials are steel, titanium, nickel and cobalt base alloys as well as materials on the basis of copper.

High-speed imaging and process characterization of coaxial laser metal wire deposition

In this work, coaxial laser metal wire deposition (LMWD) process is studied, with particular attention to defect formation mechanisms and the establishment of stable processing conditions. The coaxial LMWD of AISI 308 stainless steel wire was carried out by a multi-mode fiber laser delivered to an industrial coaxial LMWD deposition head. The continuous mechanical connection with the deposition region requires further attention to the process dynamics, which may alter the deposition precision and continuity. Accordingly, this work presents a systematic analysis of how the defects are formed at single and multiple layer deposition conditions. High-speed imaging is employed to reveal the process dynamics as a diagnostics aid. The process stability is determined initially at single layer condition, providing a correct match between the melting position and rate of the wire. At multiple layer deposition, the thermal load is managed to achieve high-aspect ratio components. At the stable conditions, the process is benchmarked for porosity, surface roughness, and deposition rates.

Modified coaxial wire method for measurement of transfer impedance of beam position monitors

The transfer impedance is a very important parameter of a beam position monitor (BPM) which relates its output signal with the beam current. The coaxial wire method is a standard technique to measure transfer impedance of the BPM. The conventional coaxial wire method requires impedance matching between coaxial wire and external circuits (vector network analyzer and associated cables). This paper presents a modified coaxial wire method for bench measurement of the transfer impedance of capacitive pickups like button electrodes and shoe box BPMs. Unlike the conventional coaxial wire method, in the modified coaxial wire method no impedance matching elements have been used between the device under test and the external circuit. The effect of impedance mismatch has been solved mathematically and a new expression of transfer impedance has been derived. The proposed method is verified through simulation of a button electrode BPM using cst studio suite. The new method is also applied to measure transfer impedance of a button electrode BPM developed for insertion devices of Indus-2 and the results are also compared with its simulations. Close agreement between measured and simulation results suggests that the modified coaxial wire setup can be exploited for the measurement of transfer impedance of capacitive BPMs like button electrodes and shoe box BPM.

Development of a PVDF Pressure Gauge for Blast Loading Measurement

We investigate the development of a sensor for dynamic pressure measurement. The sensor relies on a Bauer shock gauge of 25-μm thin Polyvinylidene fluoride (PVDF) film [AIP Conf. Proc 706:1121–1124, [21]. These gauges unfortunately require some skills to be integrated in an acquisition chain and the obtained results are strongly “experiment dependent.” In the presented work, the classical Bauer gauge has been adapted: the reproducible PVDF film is poled at high voltage, in electrical symmetrical response and reproducibility. The sensitive area is a 3 × 3 mm square. The gauge has been electrically shielded and overlaid with a heat conductive material. A 5-m long coaxial wire connects the gauge to a charge amplifier, allowing its connection to a deported oscilloscope. The output electrical charge of the PVDF gauge has been correlated with the pressure measured by calibrated PCB® sensors. Measured pressures are validated by an analytical approach and numerical simulations of the flow in the shock tube. A calibration curve can be deduced for pressures below 10 bar, values which are often met in blast loading situations. This customizable sensor is hence suitable and easy to use to measure the blast-reflected pressure on a flat material.

Improved design and in-situ measurements of new beam position monitors for Indus-2

Beam position monitors (BPM) are important diagnostic devices used in particle accelerators to monitor position of the beam for various applications. Improved version of button electrode BPM has been designed using CST Studio Suite for Indus-2 ring. The new BPMs are designed to replace old BPMs which were designed and installed more than 12 years back. The improved BPMs have higher transfer impedance, resonance free output signal, equal sensitivity in horizontal and vertical planes and fast decaying wakefield as compared to old BPMs. The new BPMs have been calibrated using coaxial wire method. Measurement of transfer impedance and time domain signals has also been performed in-situ with electron beam during Indus-2 operation. The calibration and beam based measurements results showed close agreement with the design parameters. This paper presents design, electromagnetic simulations, calibration result and in-situ beam based measurements of newly designed BPMs.

Binding energy of a hydrogenic impurity in a coaxial quantum wire with an insulator layer

The electronic properties of a coaxial cylindrical quantum well-barrier system constituted about an central insulating wire were determined under an external electric field. The model wire, inside to outside, was considered to be layered as AlAs/GaAs/Alx1Ga1−x1As/GaAs/Alx2Ga1−x2As. Within the framework of the effective mass-approximation, the binding energy of a hydrogenic impurity is calculated by using the combination of the fourth-order Runge-Kutta method and variational approaches. The binding energy exhibits sharp changes depending on the impurity position and the geometrical parameters of the structure such as the well widths of the GaAs wires and the height and thickness of the barrier constituted by Alx1Ga1−x1As. The binding energy of the electron was found to be independent from the impurity position for the specific widths of the well wires. Also, the barrier properties appeared as very effective parameters in controlling the probability distribution of the electron.

Wearable Atmospheric Pressure Plasma Fabrics Produced by Knitting Flexible Wire Electrodes for the Decontamination of Chemical Warfare Agents

One of the key reasons for the limited use of atmospheric pressure plasma (APP) is its inability to treat non-flat, three-dimensional (3D) surface structures, such as electronic devices and the human body, because of the rigid electrode structure required. In this study, a new APP system design—wearable APP (WAPP)—that utilizes a knitting technique to assemble flexible co-axial wire electrodes into a large-area plasma fabric is presented. The WAPP device operates in ambient air with a fully enclosed power electrode and grounded outer electrode. The plasma fabric is flexible and lightweight, and it can be scaled up for larger areas, making it attractive for wearable APP applications. Here, we report the various plasma properties of the WAPP device and successful test results showing the decontamination of toxic chemical warfare agents, namely, mustard (HD), soman (GD), and nerve (VX) agents.

A Comparative Evaluation of Effect of Reinforced Autopolymerizing Resin on the Flexural Strength of Repaired Heat-polymerized Denture Base Resin before and after Thermocycling.

Aims and Objective:Denture fractures are a common problem in clinical practice. Despite the use of different reinforcement materials (metal wires, metal plates, and various types of fibers) for denture repairs, recurrent fractures are still common. The purpose of this study was to compare the maximum flexural loads of the heat-polymerized denture base resin when repaired with autopolymerizing resin reinforced with relatively smaller diameter metal wires and glass fibers, before and after thermocycling.Materials and Methods:Heat polymerized rectangular specimens were fabricated and repaired with autopolymerized resin and different reinforcement materials. Stainless steel wires, coaxial wires, beta-titanium wires, and glass fibers were used as reinforcement materials. Metal wires were sandblasted before placing in the center of the specimen along with autopolymerizing resin. Control specimens were repaired without any reinforcements. Intact heat- and self-cure specimens were also prepared for comparison. Half of the specimens of each group were subjected to thermocycle stressing (5°C and 55°C, 30 s dwell time) for 2000 cycles. All the specimens, nonthermocycled as well as thermocycled, were then tested for flexural strength by using 3 point flexural test in Lloyd's Universal testing machine at 5 mm/min crosshead speed. The maximum flexural loads (N) for each specimen were recorded. The readings, thus obtained, were subjected to statistical analysis using two-way ANOVA and Tukey's multiple comparison test.Results:The metal wire reinforcements increased the flexural strength of repaired specimens, whereas, glass fiber reinforcement produced slightly lower flexural strength when compared to those of control specimens, i.e., repair without any reinforcement. The highest flexural strength was demonstrated by specimens repaired with coaxial wire reinforcements (50.01 and 43.77 N before and after thermocycling, respectively). The increase in flexural strength with the use of stainless steel wire (45.12 and 41.56 N) and beta-titanium wire reinforcements (45.54 and 42.61N) was insignificant.Conclusions:Coaxial wire reinforcement produced significantly higher flexural loads than control. Increase in strength with stainless steel wire and beta-titanium wire was insignificant, whereas glass fiber reinforcement reduced the strength.

Forces in initial archwires during leveling and aligning: An in-vitro study.

Aim:This in-vitro study measured the force deflection behavior of selected initial alignment archwires by conducting three-point bending tests under controlled tests. The study tested three wire designs, namely, co-axial multistranded stainless steel wires, nickel–titanium, and copper–nickel–titanium archwires.Materials and Methods:The archwires were ligated to a specially designed metal jig, simulating the arch. A testing machine (Instron) recorded activation and deactivation forces of different deflections at 37°C. Forces on activation and deactivation were compared by one-way analysis of variance (ANOVA).Results:Significant differences (P < 0.05) in activation and deactivation forces were observed among the tested wires. The co-axial multistranded wire had the lowest mean activation and deactivation forces, whereas conventional nickel–titanium wires had more mean activation and deactivation forces at different deflections.Conclusion:The activation and deactivation forces were higher for nickel–titanium followed by copper–nickel titanium and co-axial wires. The amount of percentage force loss was more for co-axial wire, indicating that these wires are not ideal for initial leveling and aligning.

同軸複層ワイヤを用いた純Ar-GMAWによる9%Ni鋼共金の姿勢溶接の適用検討

同軸複層ワイヤを用いた純Ar-GMAWによる9%Ni鋼共金の姿勢溶接の適用検討

High performance corrosion resistant coatings by novel coaxial cold- and hot-wire laser cladding methods

In the last few years, coaxial laser heads have been developed with centric wire feeding equipment, which enables the laser processing of complex-shaped objects in various applications. These newly developed laser heads are being used particularly in laser brazing experiments in the automotive industry. This study presents experimental results of using a coaxial laser head for cold- and hot-wire cladding application. The coaxial wire cladding method has significant improvements compared with the off-axis wire cladding method such as independence of the travel direction, alignment of the wire to the laser beam, and a reduced number of controlling parameters. These features are important to achieve high quality coatings. Cladding tests were conducted on mild steel with a coaxial laser wire welding head using Ni-based Inconel 625 and Thermanit 2509 super duplex stainless steel solid wires in order to determine the properties of the cladding process and the coatings deposited. The corrosion resistance of the obtained coatings was examined by long-term acetic acid salt spray (AASS) and electrochemical critical pitting temperature tests. The test results showed that by using the coaxial wire cladding method, defect-free high quality and corrosion resistant Inconel 625 and super duplex stainless steel coatings with low dilution were achieved. The average pitting temperature for Thermanit 2509 duplex coating was 75 °C in 1M NaCl solution, which was comparable to wrought 2507 duplex stainless steel. Low diluted Inconel 625 coating survived the AASS test for 2000 h without signs of corrosion.

A Coaxial Guide Wire–Catheter Technique to Facilitate Right Adrenal Vein Sampling: Evaluation in 76 Patients

A technique to facilitate blood sampling from the right adrenal vein is described. Between May 2012 and February 2015, 148 adrenal vein sampling (AVS) procedures were attempted. In 72 procedures, a simple 5-F end-hole catheter was employed. In 76, a coaxial guide wire technique was used when blood could not be aspirated, whereby a 0.018-inch guide wire was passed through the catheter and into a branch of the right adrenal vein and the sample was drawn around the wire by using a side-arm adaptor. Successful sampling was achieved in 71 of the 72 catheter-only procedures (98.6%) and in 75 of the 76 coaxial wire-assisted procedures (98.7%). This simple technique may eliminate the need for multiple catheter exchanges during AVS.

Development of coaxial wire reduction gear for manipulator robots

A coaxial cable drive mechanism is proposed to implement a high reduction gear ratio. The cable drive mechanism has great advantages such as lightweight, zero backlashes and high degrees of freedom in terms of mechanical design. However, it is restrictively utilised in robotic applications because it is difficult to implement a high reduction gear ratio of more than 10:1 due to the complexity of adjusting tension components, which causes the mechanical structure to be rather bulky and heavy to be mounted. To overcome this, in the present author's previous work a multi-level reduction mechanism, by adopting a seamless winding method which links the previous output axis to the next input axis, was developed. The performance of the previous work, by adopting a coaxial mechanism to drive the multi-level reduction system is improved. Significantly, the proposed mechanism reduces the overall size due to efficient integration of mechanical parts. On the basis of the proposed mechanism, a three-dimensional computer-aided design is provided and the prototype is manufactured, where the usability of the prototype is verified by experimental results.

同軸複層ワイヤを用いた純Ar-GMAWの9%Ni鋼共金溶接への適用検討

同軸複層ワイヤを用いた純Ar-GMAWの9%Ni鋼共金溶接への適用検討

Wire-shaped ultraviolet photodetectors based on a nanostructured NiO/ZnO coaxial p-n heterojunction via thermal oxidation and hydrothermal growth processes.

We report the facile fabrication of wire-shaped ultraviolet photodetectors (WUPDs) by employing a nanostructured zinc oxide (ZnO)/nickel oxide (NiO) coaxial p-n heterojunction. The WUPD consists of a ZnO/NiO coaxial Ni wire and a twisted gold (Au) wire where the Ni and Au are used as the anode and cathode, respectively. For the coaxial p-n heterojunction, the NiO nanostructures (NSs) and the ZnO nanorods (NRs) are subsequently formed on the surface of Ni wire via thermal oxidation and hydrothermal growth processes. With an applied bias of -3.5 V, the WUPD exhibits good photoresponsivity of 7.37 A W(-1) and an external quantum efficiency of 28.1% at an incident light wavelength of 325 nm. Under the UV illumination at a wavelength of 365 nm, the dark current and photocurrent are -3.97 × 10(-7) and -8.47 × 10(-6) A, respectively. For enhancing the photocurrent, the WUPD is threaded through a silver (Ag) coated glass tube which acts as a waveguide to concentrate the UV light of 365 nm on the WUPD. As a result, the photocurrent is significantly improved up to -1.56 × 10(-5) A (i.e., 1.84 times) at the reverse bias of -3.5 V.

High-performance laser cladding with combined energy sources

In the field of laser additive manufacturing, modern hybrid technologies offer advantageous solutions for combining the high quality level of laser surface claddings with the industry's economical requirements regarding productivity and energy efficiency. The technical approach is to supply energy sources in two fundamentally different ways. First, welding material in the form of wire is directly heated, i.e., by electrical resistance, almost to its melting point and is fed to the process region simultaneously with the laser beam. A newly developed coaxial wire head allows for omni-directional welding operation and, thus, the use of wire even for complex surface claddings as well as layer-by-layer fabrication of metallic parts. Second, an additional energy source is used to heat the substrate in order to compensate for the heat conduction losses. This technical variant is suitable for use with both wire and powder as deposition materials. Additionally, heating and cooling gradients can be precisely adjusted, thus improving the build-up of structures of hard and brittle metallic super-alloys. Currently, deposition rates up to 18 kg/h of metal alloys and metal matrix composites have been demonstrated using these laser hybrid techniques. Industrial applications are, among others, large hydraulic cylinders and tools of the oil and mining industries.