Resistive Insert Research Articles

A new resistance insert spot welding method for injection-molded FRP–steel component

For weight reduction, multi-material designs comprising metal and fiber-reinforced plastic (FRP) components in vehicle body structures have been increasingly used. However, the commonly used resistance spot welding (RSW) technology for car body assembly cannot be employed to join sheet metal and FRPs, limiting the use of FRPs. To solve this problem, a novel resistance insert spot welding (RISW) technique was developed in this work for RSW of steel parts and FRP structure parts made by injection molding. Small inserts were developed by using finite element method and experiments that may be welded to different micro-alloyed and dual-phase sheet steels using the projection welding method. The usual flange width of original equipment manufacturers could be kept unchanged. Using the developed insert and welding parameters, the maximum temperature in the FRPs surrounding the inserts was limited to 255 °C, minimizing the damage to polyamide 6 (PA6) material (with 40 wt% glass fiber). A weldability range between 2.5 and 7 kA could be achieved. The joining strength of RISW between a micro-alloyed HC340 steel in 0.75 mm and 1.5 mm thickness and a 2.5 mm/3.0 mm PA6-GF40 material is 20 to 80% higher than self-piercing riveting (SPR). For high-speed loading, RISW strength increases by 39 to 56% further. Finally, RISW was successfully applied to an FRP–steel roof-frame sub-assembly that consists of 19 simultaneously integrated inserts, achieving 10% weight reduction.

Knockdown of orthotospovirus-derived silencing suppressor gene by plant-mediated RNAi approach induces viral resistance in tomato

RNA interference (RNAi) shows significant effectiveness in conferring resistance to viral infections in various plants. The current study was conducted to develop transgenic tomato (Solanum lycopersicum cv. Rio Grande) lines expressing a 320 bp conserved inverted region of the integral 35S promoter region. The molecular cloning was done for the construction of expression vectors in a hairpin structure by the Tomato spotted wilt orthotospovirus (TSWV) species Orthotospovirus tomatomaculae, silencing suppressor (NSs) gene. It contains both sense and antisense orientation in a binary vector pFGC5941. Short hairpin RNA (shRNA) structures were employed to reduce the possibility of inducing endogenous non-specific antiviral responses, which usually target longer double-stranded RNAs (dsRNAs). To confirm the transgenic plants, molecular analysis was performed using TSWV gene-specific primers (TSWV-NSs). Based on the EHA105 Agrobacterium strain and the pFGC5941 vector carrying NSs and nptII genes in the T-DNA region, the results validate the insertion of kanamycin resistance into the regenerated transgenic plants. The virus source harboring TSWV was used to inoculate putative transgenic plants for evaluating the confirmation of successful transformation strategy for inducing virus resistance. Quantitative real-time polymerase chain reaction (qRT-PCR) assays were performed by using qRT-NSs primer pairs to determine the relative gene expression of all constructs (TSWV-NSs both sense and antisense orientation) after inoculations. In comparison to the control groups, which contained wild type control (non-transgenic tomato plant), empty pFGC5941 vector and the pFGC5941+sense construct, the expression of the NSs gene was noticeably reduced in the full clone (pFGC5941+sense + antisense) construct. For the validation of RNAi effectiveness, Nicotiana tabacum plants were also inoculated with viral constructs. Specifically, they displayed severe symptoms of TSWV in plants containing the pFGC5941+sense, pFGC5941 empty vector, and in wild-type tomato plants that are correlated with bioassay results. The lack of TSWV symptoms validated the hypothesis after careful observation of the expression of NSs genes in terms of pathogenicity. This research demonstrates the RNA interference effectiveness by targeting NSs gene as a reliable technique for achieving long lasting antiviral protection in tomatoes. The findings have practical relevance and the potential to be a tool for limiting tomato crop losses caused by TSWV worldwide.

Use of Newton's Method for Rotor-Resistance Control of Wind Turbine Generators

The advancement in the use of renewable sources of electricity has been promoting the manufacture of wind turbines. This paper analyzes the influence of the insertion of resistance in the rotor of induction machines during voltage sags to improve its operation and presents a new approach. The control strategy uses the Newton’s Method, which is a numerical method. A simulation in a wind generator was realized, proving the control efficiency.

The Present Status and Progress of the CHMFL 40 T Hybrid Magnet

The development of new high magnetic field facilities in the Chinese High Magnet Field Laboratory (CHMFL) will soon be completed according to the present situation. For the construction of the 40 T hybrid magnet, which will be the highest magnetic field facility in China, great progress has been achieved so far, for example, the engineering design of the resistive insert composed of six Florida-Bitter-type coils has been completed and part of the Bitter disks has been punched in Shanghai, and significant R & D progress on the design and manufacture of the superconducting outsert has been made, and the other main components of the superconducting outsert, such as?cryostat, 80 K thermal shield, vacuum pumping units, busbars, a pair of 16 kA HTS leads, overpressure protection device and so on, have been manufactured. The recent development of the CHMFL 40 T hybrid magnet is introduced in detail.

Resistance insert spot welding: a new joining method for thermoplastic FRP–steel component

Recently, multi-material designs consisting of metal and FRP components are being increasingly used in vehicle body structures to reduce weight and thus energy consumption and emission. Because the most commonly used resistance spot welding (RSW) technology for body assembly cannot be applied to join sheet metals and FRPs, the usage of FRPs is strongly limited. Therefore, a new resistance insert spot welding (RISW) method was developed. During the manufacturing process of FRPs, here compression molding of PA6 GF40 materials, specially designed steel inserts are directly integrated into the FRP part. Later, via the steel inserts, the FRP part can be spot welded to other steel parts in the structure. In this work, the design and development process of RISW is presented. Starting with the design concept of inserts, welding tests were conducted, and the parameters for the welding simulation were calibrated. After that, the detailed insert design was performed using welding simulation and tests with several restrictions, such as insert dimensions, the temperature in FRPs, the weldability range, and joining strength. In the end, an appropriate insert geometry was found, which met all requirements. The mechanical properties of RISW joining are better than or equal to those of SPRs. The new RISW technology was also demonstrated on a real vehicle component. A seat cross member was designed using FRP with 42% weight reduction and produced by compression molding with 30 simultaneously integrated inserts. The cross member was finally successfully welded to a steel closing plate using RISW.

Analysis and redesign of the thermal shield for the 40-T hybrid magnet at the CHMFL

A 40 T hybrid magnet has been constructed and commissioned at the High Magnetic Field Laboratory of the Chinese Academy of Sciences (CHMFL). It consists of a 10 T superconducting outsert magnet and a 30 T resistive insert magnet. As an important component of the hybrid magnet, the 80 K thermal shield is located inside of the cryostat protecting the superconducting magnet from thermal radiation. During the commissioning phase, a trip of the water-cooled resistive magnet triggered the quench protection system of the superconducting magnet, huge induced currents resulting in expansion and rupture of the oxygen-free copper thermal shield. In this paper, the cause of thermal shield rupture was investigated via finite element simulations. And the structure design and mechanical assessment of a new alternative thermal shield adopted for the 40 T hybrid magnet is presented.

Antimicrobial resistance genes and genetic characteristics of multidrug-resistant Escherichia coli in a veterinary hospital in Taiwan.

Introduction. Antimicrobial resistance associated with animal hosts is easily transmitted to humans either by direct contact with resistant organisms or by transferring resistance genes into human pathogens.Gap statement. There are limited studies on antimicrobial resistance genes and genetic elements of multidrug-resistant (MDR) Escherichia coli in veterinary hospitals in Taiwan.Aim. The aim of this study was to investigate antimicrobial resistance genes in multidrug-resistant Escherichia coli from animals.Methodology. Between January 2014 and August 2015, 95 multidrug-resistant Escherichia coli isolates were obtained from pigs (n=66), avians (n=18), and other animals (n=11) in a veterinary hospital in Taiwan. Susceptibility testing to 24 antimicrobial agents of 14 antimicrobial classes was performed. Antimicrobial resistance genes, integrons, and insertion sequences were analysed by polymerase chain reaction and nucleotide sequencing. Pulsed-field gel electrophoresis (PFGE), and multi-locus sequence typing were used to explore the clonal relatedness of the study isolates.Results. Different antimicrobial resistance genes found in these isolates were associated with resistance to β-lactams, tetracycline, phenicols, sulfonamides, and aminoglycosides. Fifty-five of 95 E. coli isolates (55/95, 57.9 %) were not susceptible to extended-spectrum cephalosporins, and bla CTX-M-55 (11/55, 20.0 %) and bla CMY-2 (40/55, 72.7 %) were the most common extended-spectrum β-lactamase (ESBL) and AmpC genes, respectively. Both bla CTX-M and bla CMY-2 were present on conjugative plasmids that contained the insertion sequence ISEcp1 upstream of the bla genes. Plasmid-mediated FOX-3 β-lactamase-producing E. coli was first identified in Taiwan. Forty isolates (40/95, 42 %) with class 1 integrons showed seven resistance phenotypes. Genotyping of 95 E. coli isolates revealed 91 different XbaI pulsotypes and 52 different sequence types. PFGE analysis revealed no clonal outbreaks in our study isolates.Conclusion. This study showed a high diversity of antimicrobial resistance genes and genotypes among MDR E. coli isolated from diseased livestock in Taiwan. To our knowledge, this is the first report of plasmid-mediated ESBL in FOX-3 β-lactamase-producing E. coli isolates in Taiwan. MDR E. coli isolates from animal origins may contaminate the environment, resulting in public health concerns, indicating that MDR isolates from animals need to be continuously investigated.

Longitudinal ex vivo and molecular trends of chloroquine and piperaquine activity against Plasmodium falciparum and P. vivax before and after introduction of artemisinin-based combination therapy in Papua, Indonesia

Drug resistant Plasmodium parasites are a major threat to malaria control and elimination. After reports of high levels of multidrug resistant P. falciparum and P. vivax in Indonesia, in 2005, the national first-line treatment policy for uncomplicated malaria was changed in March 2006, to dihydroartemisinin-piperaquine against all species.This study assessed the temporal trends in ex vivo drug susceptibility to chloroquine (CQ) and piperaquine (PIP) for both P. falciparum and P. vivax clinical isolates collected between 2004 and 2018, by using schizont maturation assays, and genotyped a subset of isolates for known and putative molecular markers of CQ and PIP resistance by using Sanger and next generation whole genome sequencing.The median CQ IC50 values varied significantly between years in both Plasmodium species, but there was no significant trend over time. In contrast, there was a significant trend for increasing PIP IC50s in both Plasmodium species from 2010 onwards. Whereas the South American CQ resistant 7G8 pfcrt SVMNT isoform has been fixed since 2005 in the study area, the pfmdr1 86Y allele frequencies decreased and became fixed at the wild-type allele in 2015. In P. vivax isolates, putative markers of CQ resistance (no pvcrt-o AAG (K10) insertion and pvmdr1 Y967F and F1076L) were fixed at the mutant alleles since 2005. None of the putative PIP resistance markers were detected in P. falciparum.The ex vivo drug susceptibility and molecular analysis of CQ and PIP efficacy for P. falciparum and P. vivax after 12 years of intense drug pressure with DHP suggests that whilst the degree of CQ resistance appears to have been sustained, there has been a slight decline in PIP susceptibility, although this does not appear to have reached clinically significant levels. The observed decreasing trend in ex vivo PIP susceptibility highlights the importance of ongoing surveillance.

DESIGNING MICROWAVE BAND ATTENUATORS AS ELECTRIC FILTERS WITH LOSSES

This paper presents the results of modeling attenuators with an attenuation of 1,2 dB and 1,8 dB, based on a harmonic filter with resistive inserts. Resistive inserts were introduced into the low-resistance sections of the harmonic filter, and resistive loops were connected to the high-resistance sections of the filter. An implementation of a 10 dB attenuator based on a quasi-polynomial bandpass filter with losses is proposed. The working frequency band of such attenuators reaches 4 GHz.

Fault current limiter of VSC-HVDC systems using variable resistive bridge controller

This paper proposes a fuzzy logic controller (FLC) based variable resistive bridge type fault current limiter (VR-BFCL) to minimize the impact of faults on voltage source converter high voltage direct current (VSC-HVDC) systems. FLC for VR-BFCL is developed to dynamically insert the appropriate current limiting resistance during contingencies to maintain the fault currents within the acceptable limit. The proposed controller effectively provides variable duties to generate and insert controllable resistance in the system based on fluctuation of direct current (DC) link voltage and point of common coupling (PCC) voltage. The efficacy of the proposed controller is justified through simulations work for balanced and unbalanced faults. The results demonstrate that oscillations in PCC voltage and DC link voltage can be maintained within the acceptable range by controlling fault current through the insertion of the appropriate resistance. It is also found that the proposed controller outperforms the existing method.

The thermal-hydraulic response of the superconducting outsert during the trip of the resistive magnet in the hybrid magnet system of the CHMFL

The hybrid magnet system has been completed the commissioning and be ready to serve users at the High Magnetic Field Laboratory of the Chinese Academy of Sciences (CHMFL) in Hefei, China. The hybrid magnet consists of a 28 MW, 34 T resistive insert coils set nested inside of a 800 mm bore 11 T superconducting outsert magnet. The outsert coils are wound with high JC Nb3Sn/Cu cable-in-conduit conductor (CICC), cooled with forced flow of supercritical helium at 4.5 K. The protection system of superconducting magnet is based on the classical approach of voltage detection with a co-wound coil. In this paper, we reviewed experimental behavior of the superconducting outsert in detail when the resistive insert magnet tripped. We also conducted a thermal-hydraulic performance analysis of the superconducting outsert for the same trip situation of the resistive insert with modified GANDALF code. The numerical simulation results of maximum inlet and outlet temperature show good agreement with the experimental data. In addition, the minimum temperature margin and maximum helium pressure in the superconducting conductor were introduced and discussed.

Conceptual Design for a Next Generation Resistive Large Bore Magnet at the NHMFL

The National High Magnetic Field Laboratory (NHMFL) has successfully operated its 20 Tesla 195 mm large bore magnet for over 20 years. Eventually, as there was a certain slowdown in demand for that magnet at the time, it had been decommissioned in 2016 and its two outer coils have been re-used for parts in a higher energy density configuration to facilitate the fast construction of the world record 41.5 Tesla 32 mm bore resistive magnet. Without any resistive large bore magnet providing fields in the 20 Telsa range available for the last two years, the demand or desire for such a facility has been steadily rising at our laboratory. Again, cost and schedule for the construction of such a magnet are very critical aspects under consideration. One elegant solution to keep these factors most manageable is to not design a new stand-alone magnet but to design one or a set of insert coils that is interchangeable with a smaller bore existing magnet at the NHMFL. Different alternative configurations for such a large bore resistive insert including two different existing magnets to serve as the outsert as well as different usable bore sizes have been considered on a preliminary level of detail for comparison only. Eventually, a more detailed conceptual design has been developed for a chosen magnet system. In this paper, the authors present a summary of the different alternative considerations as well as an introduction to the conceptual design of a next generation 195 mm Large Bore Magnet capable to produce well above 20 Tesla.

Impact of Failing Insert Coils on the Mechanical Design of the HFML 45 T Hybrid Magnet System

The High Field Magnet Laboratory of the Radboud University is constructing a 45 T hybrid magnet system. Large fault forces may arise in the not so unlikely event of failure of parts of the resistive insert magnet. The measures taken to accept the fault forces dominate the design of the support structures, in particular those coupling the room temperature resistive insert magnet with the superconducting coil in the cryogenic environment. The largest fault forces arise when half of one or several insert coils become electrically short-circuited in a burn-out accident. In case the complete upper or lower half of all the resistive coils collectively disappear, the so-called ultimate axial fault force on the superconducting outsert coil may amount to several MN - calculated in a static approach. Traditionally these ultimate fault forces are reference for the mechanical design to guarantee that the structures can sustain these forces preventing catastrophic failure of the magnet's housing. We will argue that if one takes into account the time dependent behavior of the powering and protection systems after detection of a coil failure, the resulting fault forces will be much smaller than the ultimate fault forces predicted by static approach.

Conceptual Design Optimization of a 60 T Hybrid Magnet

45 T is the highest continuous magnetic field available to the scientific user community, and this now since practically 20 years. We address the question of how to access the next level, defined as 60 T, with a hybrid magnet. The outsert, wound from low-temperature superconductors (LTS) will generate the highest field possible: 18–20 T in a 1 m bore. For the inner part, two approaches are investigated: a high-power resistive magnet or a combination of a resistive insert magnet and a “midsert” magnet employing high temperature superconductors (HTS). First rough estimates suggest equal field contributions of 20 T from the LTS outsert, HTS midsert and the resistive insert. We have then investigated of how to optimize dimensions and field contributions from the three subsystems under the primary constraint of actual feasibility and investment cost. Additional constraints are: a) current density and stress levels of the outsert conductor including its reinforcement, b) conductor and coil winding options and their maturity confidence for the midsert and c) stress level, power density, and available power for the insert. For insert and outsert a large basis of experience exists, from which reasonable extrapolations can be made with sufficient certainty. This is not the case for the HTS coil, where important decisions have to be justified, such as conductor type and its reinforcement, nature of insulation and winding techniques. Conductor cost reduces in our optimization routine the HTS contribution to a minimum; however, progress in HTS magnet technology and projected cost reductions are impressive; they are included in our estimations. The results of our detailed magnet design and optimization calculations indicate that it is feasible to build a 60 T hybrid magnet of rather compact dimensions with a maximum total magnet height of 1.3 m and an outer diameter of only 1.8 m. Distinct, feasible developments of the HTS and LTS conductors and resistive magnet technology have been defined. We propose a novel method, the fast ramp-down of the resistive insert, to safely protect the HTS midsert by quenching it globally and instantaneously.

From Manufacture to Assembly of the 43 T Grenoble Hybrid Magnet

The Grenoble Hybrid magnet is a modular platform applying resistive and superconducting technologies to deliver various continuous high magnetic field and flux configurations. They range from 43 T in 34 mm diameter with 24 MW down to 9 T in 800 mm with the superconducting coil alone. Thanks to the ongoing upgrade of the electrical power installation of LNCMI-Grenoble up to 30 MW and possibly to 36 MW, the possibility to increase the total field up to 45–46 T in the future is considered and needs to be assessed by further dedicated studies. The key design parameters are recalled including the specifically developed superconducting conductor, the large bore outsert coil, the cryostat with the eddy-current shield and the cryogenic infrastructure. Most of the equipment of the hybrid magnet outsert has been built, tested and delivered to LNCMI-Grenoble, where integration and assembly is ongoing. The dedicated material development program initiated for the innermost resistive insert is in progress. The status of the project is given together with the main problems encountered and solved. The commissioning of the overall hybrid magnet system will start in 2020 and will be followed possibly by the first run of a new axion dark matter search experiment in preparation.

Design of a fast field-cycling magnetic resonance imaging system, characterization and methods for relaxation dispersion measurements around 1.5 T.

The dependence of the nuclear magnetic resonance relaxation rate on the magnetic field has been widely studied, in particular, in biomedical areas with the objectives to better understand the underlying microscopic mechanisms in tissues and provide biomarkers of diseases. By combining fast-field cycling (FFC) and magnetic resonance imaging (MRI), it is possible to provide localized relaxation dispersion measurements in heterogeneous systems with recent demonstrations in solutions, biological samples, human beings, and small animals. We report here the developments and performances of a device designed for small animal FFC-MRI comprising a resistive insert technology operating inside a 1.5 T MRI system. Specific measurement methods were developed to characterize the system efficiency, response time, homogeneity, stability, and compensation. By adding a non-linear element in the system and using a dual amplifier strategy, it is shown that large field offsets can be produced during relaxation periods while maintaining precise field control during detection periods. The measurement of longitudinal nuclear magnetic relaxation dispersion (NMRD) profiles in the range of 1.08 T-1.92 T is reported, essentially displaying a linear variation in this range for common MRI contrast agents. The slopes of both the longitudinal and transverse relaxation dispersion profiles at 1.5 T are measured and validated, extending the capabilities of previous approaches. The performances of a longitudinal relaxation dispersion mapping method are finally reported, opening the way to quantitative preclinical dispersion imaging studies at a high FFC-MRI field.

Design of the Resistive Insert for the Nijmegen 45 T Hybrid Magnet

This paper presents the design of the resistive insert magnet for the 45 T hybrid magnet under construction at the High Field Magnet Laboratory (HFML) in Nijmegen. We describe the design process and tools used to obtain the coil and disk design, and we describe the mechanical design aspects of the housing for the magnet. We address the end turn issue and introduce an innovative new element to provide sufficient clamping of the coil at all times. Finally, we address possible fault scenarios and the magnetic misalignment forces associated with such faults and their impact on the housing.

Non-Linear Control for Variable Resistive Bridge Type Fault Current Limiter in AC-DC Systems

This paper proposes a non-linear control-based variable resistive bridge type fault current limiter (VR-BFCL) as a prospective solution to ease the effect of disturbances on voltage source converter-based high voltage DC (VSC-HVDC) systems. A non-linear controller for VR-BFCL has been developed to insert a variable optimum resistance during the inception of system disturbances in order to limit the fault current. The non-linear controller takes the amount of DC link voltage deviation as its input and provides variable duty to generate a variable effective resistance during faults. The VSC-HVDC system’s real and reactive power controllers have been developed based on a current control loop where direct axis and quadrature axis currents are used to control the active and reactive power, respectively. The efficacy of the proposed non-linear control-based VR-BFCL solution has been proved with balanced as well as unbalanced faults. The results confirm that the oscillations in active power and DC link voltage have been significantly reduced by limiting the fault current through the insertion of an optimum effective resistance with the proposed control technique. The real time digital simulator (RTDS) has been used to implement the proposed approach. The performance of the proposed non-linear control based VR-BFCL is compared with that of traditional fixed duty control.

In-House Industrial Production of the Superconducting Conductor for the 43 T Hybrid Magnet of LNCMI-Grenoble

The hybrid magnet being built at LNCMI-Grenoble is based on the combination of resistive inserts, made up of Bitter and polyhelix coils, with a large bore superconducting outsert. It will produce, in the first step, an overall continuous magnetic field of 43 T in a 34 mm warm bore aperture. The superconducting coil will provide a nominal magnetic field of 8.5 T in a 1.1 m cold bore diameter. It relies on the novel development of an Nb-Ti/Cu Rutherford Cable On Conduit Conductor (RCOCC) cooled down to 1.8 K by a bath of superfluid helium pressurized at 1200 mbar. After a brief reminder of the specificity of hybrid magnets, namely the strong electromechanical coupling between resistive and superconducting coils, the main requirements of the RCOCC for efficient and reliable magnet operation are given. The test and validation phases prior to the industrial production of the RCOCC are reported, including the trial production of the ½ hard-drawn (H02 cold-worked) Cu-Ag 0.05% hollow stabilizer in continuous lengths of 325 m. The novelty of the RCOCC development concerns the assembly and the induction soft-soldering of the Rutherford cable on the Cu-Ag hollow stabilizer allowing a strict control of the interstrand contact resistance. Studies, developments, and the integration of the industrial production line at LNCMI-Grenoble are presented together with the result of the production of all RCOCC unit lengths.

Progress in the Construction of the 43 T Hybrid Magnet at LNCMI-Grenoble

By combining resistive polyhelix and Bitter insert coils with a large bore superconducting outsert one, the new hybrid magnet in construction at LNCMI-Grenoble will produce an overall continuous magnetic field of 43 T in a 34-mm warm bore aperture. After a brief reminder of the specificity of hybrid magnets, namely the strong electromagnetic and mechanical coupling between resistive and superconducting coils, the main specificities of the proposed design are presented. The superconducting coil of 1.1-m cold bore diameter will provide a nominal magnetic field of at least 8.5 T. It relies on the specific development of the Nb–Ti/Cu Rutherford cable on a conduit conductor (RCOCC) cooled down to 1.8 K by a bath of superfluid helium pressurized at 1200 mbar. The novelty of the RCOCC concerns the in-laboratory assembly with induction soft-soldering of the Rutherford cable on a Cu–Ag hollow stabilizer, allowing a strict control of the quantity of the solder alloy used and therefore of the interstrand contact resistance. A stainless steel reinforced copper shield inserted between the superconducting and resistive coils will reduce the coupling currents induced within the RCOCC, as well as the mechanical force exerted on the superconducting coil. After successful thorough reviews of the Grenoble hybrid magnet design anticipating possible upgrades of the maximum magnetic field that can be produced, this project is now well engaged in its construction phase. The status of this project is presented in details together with the next milestones.