Electrical Joints Research Articles

Simultaneous Calibration of a Hexapod Robot and an IMU Sensor Model Based on Raw Measurements

A simulation model contributes to the development of both algorithms based on navigation sensors and their application in real nonlinear mechatronic systems. The Szabad(ka)-II hexapod walker robot is equipped with an inertial measurement unit (IMU), and this paper presents a novel calibration procedure of its simulation model. Various sinusoidal calibration movements were performed on both the model and the robot, and the raw IMU measurements were recorded simultaneously with motor electrical parameters and joint movement variables. The simulation model includes the model of IMU sensors, where the location, misalignments, and scaling parameters are also incorporated in the tuning procedure. Thus, this simulation environment enabled the calibration procedure to be performed based on the measurement data. The efficient optimization of both the unknown and estimated parameters of the robot model along with the IMU sensor model resulted in a simulation output that fits the measurement results satisfactorily. The nominal and remaining errors were analyzed both statistically and in the spectral domain. Due to the proposed method, the simulation error of the accelerometer and gyroscope measurements were decreased by 35%. The necessity of calibrating the sensor model was justified via the application of an extended Kalman filter (EKF) for the attitude estimation.

Human motion intention recognition based on EMG signal and angle signal

As the traditional single biological signal or physical signal is not good at predicting the angle value of the knee joint, the innovative fusion of biological signals and physical signals is used to analyze the movement posture of the lower limbs. In order to solve the problem of human movement intention recognition, a wearable is designed. The signal-acquisition experiment platform uses muscle electrical signals and joint angle signals as motion data. After the signals are processed, the KNN algorithm is used to identify the four gait motion modes of the human body to walk naturally, climb stairs, descend stairs, and cross obstacles. The test results show that it is feasible to use the KNN algorithm to analyze the strength of the active and passive muscles of the knee joint movement according to different thigh lift heights, and to predict the knee joint angle value when the human body goes up and down the stairs. The comprehensive prediction accuracy rate reaches 91.45%.

Fabrication and characteristics of Cu@Ag composite solder preform by electromagnetic compaction for power electronics

Abstract Cu@Ag core-shell material not only has advantages of Cu and Ag elements but also inhibits Ag migration and Cu oxidation issues, showing potential in die attachments for power electronics. Currently, micro/nano sintering has been widely used for die attachments and inevitably forms residuals and voids due to solvents, leading to poor bonding strength and weak reliability. In this work, a high-temperature Cu@Ag solder preform was firstly fabricated by electromagnetic compaction (EMC) on Cu@Ag core-shell powder. Unlike conventional solder preforms, a void-free joint can be directly achieved with this Cu@Ag solder preform by simple thermal compression at low temperature and pressure without melting. Moreover, with the benefits of high-energy forming process, other vital properties of solder preforms, including electrical property, thermal stability, corrosion resistance and joint integrity, were also improved compared to conventional die attach materials. For instance, the corrosion potential of this Cu@Ag solder preform was −0.14 V, which indicates excellent corrosion resistance similar to pure Ag (−0.12 V). And no oxidation can be detected on this solder preform after storage in air for at least one year. These performance improvements were a result of enormous pressure generated instantaneously on Cu@Ag powder during EMC. The results showed that a flaw-free Cu@Ag solder preform with a high compactness of over 99 % can be successfully fabricated by appropriate compaction pressure of 13.4 MPa.

Снижение переходного сопротивления разборных контактных соединений с помощью сплавов галлия

The article studies the possibility of reducing the transition resistance of demountable electrical contact joints in laboratory conditions by using multicomponent gallium alloys. The relevance of the chosen topic is attributed to the need for reducing energy losses and improve the reliability of a contact network.

R&D Activities of Joint Manufacture for CFETR CSMC

The Central Solenoid Model Coil (CSMC) project was launched in the Institute of Plasma Physics Chinese Academy of Sciences for the China Fusion Engineering Test Reactor (CFETR). The CFETR CSMC is designed to generate 12 T peak magnetic field when the running current is 47.65 kA. The CSMC is composed of two Nb3Sn coils in the internal high field and three NbTi coils in the external low field. Electrical joints are one of the key technologies for the CSMC, because the superconducting coils are electrically connected into a single circuit by the joints. Lap type joints have been designed for the CSMC for its proven reliability and easy assembly. It is a great challenge to develop special equipment and technologies for the joint manufacture, including vacuum brazed terminal sleeve assembly, jacket removal, chrome coating removal for Nb3Sn cable, nickel coating removal and silver plating for NbTi cable, compact termination, etc. This paper mainly focuses on the research and development activities of the joint manufacture and the solution of the technical issues. The techniques and equipment can provide a basis for the electrical joint manufacture for the CSMC and other large-scale superconducting magnets.

A new concept for developing a compact joint structure for reducing joint resistance between high-temperature superconductors (HTS) and low-temperature superconductors (LTS)

It is significantly difficult to develop a superconducting joint between REBCO and low-temperature superconductors (LTS) using a solder matrix replacement technique. This is because the REBCO superconducting layer is highly corrosive to Sn. In this work, TEM observations were first conducted on the reaction interface between the REBCO layer and Sn to reveal the reaction. Then, a new idea to create a compact low-resistance joint to reduce the joint resistance between REBCO and LTS was proposed. In this method, the REBCO tape is rolled in a metal boat, with the Cu stabilizer remaining around the tape. Then, an LTS wire, whose superconducting filament ends are coated with a superconducting solder, is set straight into a boat. Then, the boat is filled with a superconducting solder, so that the joint state between the LTS and superconducting solder matrix remains superconductive. However, the electrical joint between the REBCO tape and the solder matrix is resistive, even if the solder matrix is superconductive. Consequently, the overall joint resistance is determined by the boundary resistance between the REBCO tape and the superconducting solder matrix. However, to achieve a joint resistance below 10–10 Ω, a long joint length of more than 5 m, preferably more than 10 m, will be required. Considering the strain state of the REBCO layer when it is rolled in to a boat, the boat-type joint structure proposed in this work enables the joint size to be significantly compact, even if a length of more than 10 m is required. At present, a joint resistance of 0.7 nΩ was obtained in a field range of less than 0.4 T by using a boat with an inner size dimensions as follows: 50 mm length, 16 mm width, 7 mm height, radius of curvature of 8 mm, and tape length of 2 m.

VIPER: an industrially scalable high-current high-temperature superconductor cable

High-temperature superconductors (HTS) promise to revolutionize high-power applications like wind generators, DC power cables, particle accelerators, and fusion energy devices. A practical HTS cable must not degrade under severe mechanical, electrical, and thermal conditions; have simple, low-resistance, and manufacturable electrical joints; high thermal stability; and rapid detection of thermal runaway quench events. We have designed and experimentally qualified a vacuum pressure impregnated, insulated, partially transposed, extruded, and roll-formed (VIPER) cable that simultaneously satisfies all of these requirements for the first time. VIPER cable critical currents are stable over thousands of mechanical cycles at extreme electromechanical force levels, multiple cryogenic thermal cycles, and dozens of quench-like transient events. Electrical joints between VIPER cables are simple, robust, and demountable. Two independent, integrated fiber-optic quench detectors outperform standard quench detection approaches. VIPER cable represents a key milestone in next-step energy generation and transmission technologies and in the maturity of HTS as a technology.

NEUROLOGICAL PHYSIOTHERAPY IN LABRADOR RETRIEVER DOG WITH PARAPARESIS: A CASE REPORT

Background: Spinal cord injuries (SCI) may cause neurological problems such as muscle weakness, sensory disorders, and incontinence. This case report aims to investigate the effectiveness of the sensorimotor rehabilitative physiotherapy program in a dog with paraparesis.Case Description: A 1-year-old, 27 kg male dog was brought to Near East University, Animal Hospital, after a motor vehicle accident. The dog was diagnosed as a T13 vertebral fracture and luxation at the T13-L1 spinal level according to the clinical and radiological examination performed by a veterinary physician. The dog showed; poor standing, weakness in the hind limbs and back muscles, urinary and fecal incontinence at the clinical examination. The physiotherapy program included; massage, sensory stimulation applications, Neuromuscular Electrical Stimulation (NMES), joint mobilizations, standing-balance exercises, and gait training.Outcome Measures: Consequently, improvements were obtained in standing and sitting balance, gait, bladder, and bowel functions at the end of the seven-week treatment period. The standing duration increased from 3 sec to >60 sec; also, thigh circumferences increased from 31cm to 36 cm in the right and 32 cm to 36 cm in the left limb. Canine Acute Pain Scale score was reduced from 2 to 1 in a positive sense.Conclusion: There were a satisfying motor and functional recovery in our case. We believe that the dog’s young age and the type of injury (neurapraxia) contributed to these positive results. Therewithal, early and active physiotherapy program plays a crucial role in maintaining functional independence, also coping with the symptoms in the dog.

Multichannel Parallel Testing of Intermittent Faults and Reliability Assessment for Electronic Equipment

Many connections exist in complex electronic equipment, which leads to a long duration of intermittent fault test and difficulty in achieving comprehensive coverage of intermittent fault. The intermittent fault mechanism and the multichannel intermittent fault parameter parallel capture method are investigated. A smaller module covers multiple intermittent connection faults in electronics and prevents missed detections. Based on the test results, a reliability assessment of the connection link with intermittent faults is needed in the next step. The correlation between the intermittent fault parameters and the reliability of connection link is analyzed, and the intermittent fault parameters are used to evaluate the connection link reliability. An aviation electrical connector and solder joint are used for testing. The results show that increases in the intermittent fault parameters are consistent with the trend of reliability degradation, which indicates that the proposed method can be applied to intermittent fault testing and reliability assessment for the connection link of electronic equipment.

Prediction and Optimization of Parameters for the Al5083/ B4C Composite Wear Rate

Background:Al5083 has been basically used in marine and aerospace applications where it is intended for higher corrosion resistance and better weldability. Again this, Al5083 matrix has not been suitable for various other applications such as electrical contact brushes, cylinder liners, artificial joints and helicopter blades due to its poor wear resistance properties.Objective:The aim of this research is the optimization of wear rate of the composite with Al5083 matrix, reinforced with B4C (Boron carbide) particles, and it is achieved through the investigation of the subsequent effect: wt.% of the reinforcement, applied load and sliding speed.Methods:The material used for specimen is Al5083 and Al5083/B4C composite which is melted at 750°C in an induction furnace; the composite is prepared by stir casting technique. It was developed by an ex-situ technique. The liquid melt poured into preheated cast iron mould for carrying out the specimen preparation of wear testing.Results:The wear rate of Al5083/B4C composite is less than Al5083, the most influencing factor on wear rate is applied load and mechanism of deformation induced in the sliding surface of the pin was analysed by SEM (scanning electron microscope).Conclusion:Wear rate of Al5083 and Al5083/B4C composite increases with the increase of applied load, sliding speed and decreases as the wt. % B4C increases. The contribution of applied load is more in wear rate as compared to the other two factors and the value predicted by Taguchi, obtained by RSM (Response surface methodology) and evaluated by experiment are almost similar.

An engineering site investigation using non-invasive geophysical approach

Subsurface geological formation is essential to validate design assumptions for the construction of deep engineering structures, especially in the weathered terrains. The geological formation can be delineated using resistivity values through an electrical survey. However, the subsurface resistivity alone is ambiguous to interpret the subsurface geological units. As part of an ongoing investigation to select the key methods towards this end, an integrated geophysical survey through a combination of electrical resistivity tomography (ERT), induced polarization (IP), magnetic method and joint profile method (JPM) was carried out in a weathered terrain of South Huizhou, China. Resistivity, IP, and magnetic data were obtained using a variety of survey parameters. Subsurface resistivity was calibrated with upfront boreholes lithology to constrain geological formation into four discrete layers such as topsoil cover with resistivity 2–3257 Ωm, highly weathered layer having resistivity 2–636 Ωm, partly weathered layer with resistivity range 448–1204 Ωm, and unweathered bedrock having resistivity 791–116,497 Ωm. The integration of ERT with IP, magnetic and JPM delineated four faults namely F1, F2, F3 and F4, and several localized fractures. The weathered layer, fractures and faults were marked as the weakest zones for engineering projects, whereas the unweathered fresh bedrocks were identified as the most appropriate locations for the construction of deep structures in the study area. The weakest zones unsuitable for engineering structures were delineated as the most appropriate places of groundwater occurrence in the studied area revealed by low resistivity ranging from 2 to 1204 Ωm and overlapped by low chargeability less than 14.8 ms. This non-invasive geophysical approach suggests the most suitable locations highly significant not only for the future construction of engineering structures but also the exploitation of groundwater resources in the investigated area.

Feedback Control to a Static Target Angle in the Middle Finger Metacarpophalangeal Joint Using Functional Electrical Stimulation

ABSTRACT In this study, we proposed a feedback control method for a finger joint angle, which has been considered difficult, via functional electrical stimulation using the surface electrode method. If detailed finger movement can be realized by functional electrical stimulation using the surface electrode method, this can be applied in various situations such as musical instrument performance, daily movements, and so on. The control method was designed based on the following three proposals. First, the non-linear relationship between the electrical stimulation intensity and joint angle change was absorbed by constructing polygonal line regression models of the relationship between the electrical stimulation intensity reaching each muscle and the flexion and extension force of the middle finger’s metacarpophalangeal joint. Second, the concepts of the muscle antagonist ratio and muscle antagonist sum were adopted to translate the input/output relationship to a single-input/single-output system while maintaining joint stiffness. Finally, the proportional–integral–derivative control parameters were determined using the Ziegler–Nichols ultimate sensitivity method. Using the control method based on the aforementioned three proposals, we conducted feedback control experiments for three static target angles in the middle finger’s metacarpophalangeal joint. Results show that at all target angles, greater than 80% of the participants were able to control the joint with nearly no error. Therefore, the control method proposed in this study can be used to control an arbitrary static target joint angle with high accuracy via functional electrical stimulation.

Study and Characterization of the Dielectric Behavior of Low Linear Density Polyethylene Composites Mixed with Ground Tire Rubber Particles.

The waste rubber vulcanizate, on account of its stable, cross-linked and three-dimensional structural arrangement, is difficult to biodegrade. Thus, the ever-increasing bulk of worn-out tires is a serious environmental issue and its safe disposal is still a challenging task reported widely by the scientific community. The rubber materials, once they end their useful life, may present difficulties to be reused or recycled. At present, only one tire recycling method is used, which involves grinding and separating steel and fibers from vulcanized rubber, and then using rubber for industrial applications, such as flooring, insulation, footwear. In this paper, a new compound material is presented from a base of reused tire powder (Ground Tire Rubber: GTR) as a mixer and linear low-density polyethylene (LLDPE) as a matrix. The reused tire powder, resulting from grinding industrial processes, is separated by sieving into just one category of particle size (<200 μm) and mixed with the LLDPE in different amounts (0%, 5%, 10%, 20%, 40%, 50% and 70% GTR). Due to the good electrical properties of the LLDPE, this study’s focus is settled on the electrical behavior of the obtained composites. The test of the dielectric behavior is carried out by means of DEA test (Dynamic Electric Analysis), undertaken at a range of temperatures varying from 30 to 120 °C, and with a range of frequencies from 1 to 102, to 3·106 Hz, from which permittivity, conductivity, dielectric constant and electric modulus have been obtained. From these experimental results and their analysis, it can be drawn that the additions of different quantities of GTR to LLDPE could be used as industrial applications, such as universal electrical cable joint, filler for electrical applications or cable tray systems and cable ladder system.

Scalable fabrication of highly crosslinked conductive nanofibrous films and their applications in energy storage and electromagnetic interference shielding

With their unique properties and potentials in several critical applications, highly crosslinked and conductive nanofibrous films (HCC-NFs) have attracted broad attentions recently. However, it is still a great challenge to produce high-performance and uniform HCC-NFs with controllable thickness on a large-scale. Electrospinning could be used to fabricate nanofiber films, but it falls short in creating intimate mechanical and electrical joints between adjacent nanofibers for crosslink. Herein, a new strategy inspired by the fabric shrinking when drying was applied to produce HCC-NFs. Hydrophilically-engineered electrospun polyacrylonitrile (PAN) nanofiber film was dip-coated in a water solution of PEDOT:PSS, and was then dried naturally. By preventing contraction of the film in its lateral plane while allowing its thickness shrinking, the capillary effect during water evaporation resulted in collapse of the large pore volume in the film and the subsequent joint formations between PEDOT:PSS-coated PAN nanofibers, which are further cemented together by the conductive polymer coating. The electrochemical, electrical and mechanical properties of such fabricated HCC-NFs were studied, and they were successfully applied as electrodes to demonstrate high-rate supercapacitors and as a flexible porous material for electromagnetic interference (EMI) shielding. The studies suggest HCC-NFs produced by this facile method have promising prospects in several applications.

Modelling and prediction of strength of ultrasonically welded electrical contact joints using Artificial Neural Network

Abstract Ultrasonic welding is an advanced green solid state welding process used to weld similar or dissimilar materials of same or dissimilar shapes. Ultrasonic welding is used to join both conductive and non-conductive materials. Copper is an excellent conductive non-ferrous metal widely used in wide variety of electrical and electronic components manufacturing applications. Many electrical components have a need to join copper wire to copper sheet and these applications demands inevitably for superior weld strength. In this paper, ultrasonic welding is carried out on copper wire-sheet to produce quality electrical contact joints. The present study deals with the formulation of mathematical model between the predominant input parameters such as clamping force, amplitude of vibration of sonotrode and weld time and the output parameter such as weld strength using Artificial neural network and regression technique. Based on the results from experiments and prediction models, the ANN model is found to be effective when compared with the developed third order polynomial regression model

Using Expert Knowledge to Generate Data for Broadband Line Prognostics Under Limited Failure Data Availability

Due to exposure to the driving rain, water ingress can cause faults in electrical joints, junctions and distribution points in broadband lines. Over time, faulting behaviour may grow in magnitude eroding the electrical capability of these lines causing degradation of broadband service. Developing effective data-driven models for broadband line prognostics remains a challenge due to the limited failure data availability in the telecommunications industry. In order to address this problem, we present a technique for generating failure data that realistically reflect the behaviour of degrading broadband lines. To this end, we use the conditional generative adversarial network and more importantly, we control and direct the failure data generation process using expert knowledge on the water ingress failure cause. The proposed technique is evaluated using a real-world case study involving the time-to-failure prediction of two types of broadband lines in a south-west city in England. The prognostics performance is measured using the Kappa statistic and F-score. Benchmark performance is obtained using Random Oversampling, Synthetic Minority Oversampling and Adaptive Synthesis which can be used to oversample failure data by duplicating existing failure data or randomly generating data. Among these techniques, Random Oversampling achieved the best prognostics performance. It is shown that the proposed technique outperforms Random Oversampling technique by a large margin. More specifically, it increased the prognostics performance by 33% (Kappa statistic) and 25% (F-score) for Asymmetric Digital Subscriber Lines, and 17% (Kappa statistic) and 13% (F-score) for Very High Bitrate Digital Subscriber Lines compared to the Random Oversampling technique.

Exploration of Dancun-Longyang town fault at the site about project of LNG peak shaving station and gas supply pipeline in Luyang Lake

In this paper, the method of combining high-density electrical exploration and borehole joint profile is used to explore the Dancun-Longyang town fault at the LNG peak shaving station and gas supply pipeline engineering site of Luyang lake. The distribution and activity of the fault are determined, providing a basis for seismic fortification and seismic geological disaster evaluation in the line

Experimental Studies on the Effect of Different Field Shaper Geometries on Magnetic Pulse Crimping in Cylindrical Configuration

Copper-aluminum composite rods are a substitution for copper rods, result in both cost and weight reduction. The electromagnetic pulsed crimping technique, which is based on high-velocity impact, offers many advantages by utilizing a part of total stored energy on the capacitor bank to fabricate composite rods. The application of field shaper in electromagnetic pulsed crimping not only increases the effectiveness of the process but also increases the life or strength of the working coil. The effect of geometry of three types of field shaper on the plastic deformation of the composite rod was investigated to facilitate the field shaper design. The field shaper variation was done by changing the cross-section namely tapered, step-tapered, and stepped. It was found that the step-tapered field shaper results better in terms of uniformity in crimp quality, joint strength in compression, joint strength in tension, joint electrical resistance, joint leakage, and surface finish of the crimped sample among the three types of field shaper. This work will be of use for designing of field shaper for producing joint by electromagnetic pulsed crimping.

The Effect of Specific Manufacturing Characteristics on PF ITER Full-Size Joint Performance

The development of new generation superconducting magnets for fusion research, such as the ITER experiment, is largely based on coils wound from so-called “Cable-In-Conduit” Conductors (CICCs). CICCs consist of various types of stainless steel jackets, densely filled with compacted superconducting strands, which are cooled by supercritical helium. The design of the various magnet systems, and in particular the ITER Poloidal Field (PF) coils, imposes the use of electrical joints to connect unit lengths of the CICCs. The electrical joints are delicate, electrical resistive components, carefully designed to provide efficient high current transfer while avoiding heat generation. The PF joints are subjected to fast varying magnetic fields that induce currents which, combined with the Joule heating in the resistive joints due to transport current, increase the temperature of the helium. Various characteristics, including electrical performance and mechanical behavior, have been addressed in the past in order to optimize manufacturing for satisfactory joint operation. Here an extensive post-mortem characterization of pre-qualification full-size PF joints is reported. Void fraction, twist pitch, and the current path connection are investigated in order to understand their effect on electrical performance and tune the manufacturing processes.

Effects of Combined Functional Electrical Stimulation and Joint Mobilization on Muscle Activation and Mobility of Ankle Joints and Modified Functional Reach Test in Stroke Patients

Effects of Combined Functional Electrical Stimulation and Joint Mobilization on Muscle Activation and Mobility of Ankle Joints and Modified Functional Reach Test in Stroke Patients