Discharge Amplitude Research Articles

Successful Rectification of Cervical Nerve Root Irritation with Sequential Surgical Maneuvers during Posterior Cervical Instrumentation

AbstractPosterior cervical instrumentation is used to treat a variety of cervical pathologies, including cervical spondylotic myelopathy, severe canal stenosis, and degenerative diseases. A 55-year-old man with severe cervical canal stenosis underwent a C3–C6 laminectomy and lateral mass screw fixation under general anesthesia. After lateral mass screw fixation and rod placement on the right side, raw electromyography (EMG) revealed irritative discharges in the right biceps brachii muscle. Following a suspicion of irritation/mechanical stretching of the C5–C6 nerve root, a posterior foraminotomy was performed on the right side as a rescue measure. The amplitude of raw EMG irritative discharges in the right biceps brachii muscle decreased significantly after posterior foraminotomy. Following rod reapplication with decreased rod lordosis, the irritative EMG discharges were eliminated. Before implementing further measures, posterior foraminotomy can be a crucial initial intervention for minimizing nerve root irritation due to mechanical factors after cervical lateral mass screw fixation.

Research on Partial Discharge Characteristics of Suspension Defect in GIS under the Action of Voltage and Current

Abstract Gas insulated switchgear (GIS) is a critical component in power system, and the insulation testing is crucial before putting it into operation. Despite passing AC withstand tests, some GIS equipment exhibit insulation faults during operation. Existing AC withstand tests fall short in detecting all insulation faults in GIS equipment. To address this issue, a proposal is made to conduct a comprehensive simulation of actual GIS equipment operating conditions through a combined voltage and current boost test, aiming to address the limitations of existing tests. This study, based on a 330kV GIS test platform, compares the partial discharge characteristics of suspension defects under traditional voltage-boosting mode and the combined voltage and current boost mode. The research investigates the influence of simultaneously applying voltage and current on discharge characteristics. It is observed that the voltage and current boost combined mode significantly increase the partial discharge inception voltage (PDIV) and the corresponding apparent discharge compared to other modes. The apparent discharge quantity after a certain period of current flow during the discharge development process is greater than that observed in other modes. The current notably enhances the ultrasonic amplitude of partial discharge. These findings establish an experimental foundation for conducting voltage and current combined boost tests in the field.

Respiration and Cough in Pompe Disease: Results from a neuromechanical computational model of the respiratory control system

Late Onset Pompe Disease (LOPD) is an incurable, rare progressive genetic disease. It is characterized by glycogen build-up, due to mutations in the gene encoding the lysosomal enzyme acid alpha glucosidase, throughout muscle and neural regions. This accumulation is associated with cell death and muscle fiber swelling, eventually leading to respiratory insuffciency and airway clearance (i.e. cough) deficiency. Impairments in effective airway clearance result from the inability to clear normal pulmonary volume. Emerging evidence indicates significant respiratory neuron dysfunction, altering pulmonary function in humans and animal models. It has been suggested that respiratory and airway clearance insuffciency observed in LOPD may be attributed to medullary motoneurons potentially associated with the respiratory and cough pattern generators (Fuller et al., 2013; DeRuisseau et al., 2009). However, the precise neural mechanisms that suppress breathing and cough are not fully understood. One possible target for LOPD respiratory insuffciencies may be reduced medullary inspiratory neuron activity within this network, which could result in decreased phrenic motoneuron output. Using a stochastic neural network simulator that consisted of discrete “integrate and fire” populations, we simulated a systematic decrease in three medullary inspiratory neuron populations: inspiratory driver (I-Driver), inspiratory decrementing (I-Dec), or inspiratory augmenting (I-Aug) neurons. We simulated breathing and three cough trials. By targeting these populations, we expected global decreased neural bursts, suppressed inspiratory motor drive, and/or suppressed expiratory motoneuron output. Simulations indicated that when the I-Dec motoneuron population decreased by 25%, it resulted in apnea and abolished cough. Reducing the I-Aug motoneuron population by 20% resulted in longer inspiratory phase durations (TI) and a decreased respiratory rate. During cough, there was a decrease in the duration and amplitudes of the expiratory motoneuronal activity associated with decreased cough receptor and pulmonary stretch receptor afferent feedback. When the I-Driver motoneuron population was reduced by 25%, TI decreased and I amplitude increased during respiration. During cough, lumbar and phrenic motoneuron discharge duration and amplitude decreased. These results are consistent with previously reported in vivo data. Overall, our simulation data support the plausibility of glycogen storage dysfunction impairing medullary neuronal and premotoneuronal excitability within the inspiratory network. Our results also suggest that some neurons may be more sensitive to glycogen storage than others within the brainstem inspiratory network. Supported by NHLBI L30HL165496, NIH T32 HL 134621 and 3OT2OD023854. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The effect of acute and chronic harmaline administration on penicillin induced epileptiform activity in rats

Aim: The electrophysiological impact of short-term and long-term harmaline treatment on the penicillin G-induced epileptic model in rats was examined in this study. Methods: Eighty-four adult male Wistar rats were randomly assigned to two groups: one received a single dose of harmaline, and the other received repeated doses of harmaline. Each group was further divided into six subgroups based on the dose of harmaline (0, 10, 50, or 100 mg/kg) or penicillin (control or sham). The electrophysiological data were collected using electrocorticography and analyzed using PowerLab Chart v.8 software. The statistical analysis included the latency, frequency, and amplitude of the spike-wave discharges. The serum levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) were measured using the ELISA method to assess the antioxidant effects of harmaline. Results: The results showed that both acute and chronic harmaline treatment increased the seizure threshold in a dose-dependent manner (p

Research on discharge process of Bi2Te3 module under different thermal stimulation conditions

In the actual working process, the working environment temperature of the thermoelectric device is constantly changing, and rarely remains stable, a thermoelectric device is composed of more than one thermoelectric module monomer (PN junction), each of which can be used as an independent research object. To address this issue, the thermoelectric properties of thermoelectric modules (p, n-type Bi2Te3) are measured under different temperature environments. A self-constructed thermoelectric performance test platform, an infrared thermal imager, and a voltage acquisition system are used to monitor different temperature difference conditions in real-time. A transient discharge evaluation model was established to calculate the real-time discharge amplitude of the thermoelectric module based on its temperature gradient distribution. The results show that the error of the transient discharge evaluation model is about 5%, which is reliable. For large-sized thermoelectric modules, the maximum discharge amplitude under open circuit voltage can be obtained solely based on the overall temperature gradient of the thermoelectric module; the amplitude of the electrical output signals increases uniformly when the temperature difference between the two ends of the module is increasing uniformly; and the stable electrical output signals are also produced at both ends of the module when the temperature difference is stabilized. After stabilization, when the temperature drops uniformly, the amplitude of the electrical output signal decreases uniformly. In the range of T = 298–573 K, the greater the temperature difference between the two ends of the thermoelectric module is, the greater the amplitude of the stabilized electrical output signal is; and vice versa. The greater the rate of thermal loading, the faster the increase in the amplitude of the electrical output signal at both ends of the thermoelectric module. This also reduces the time needed to reach steady state equilibrium, enabling the thermoelectric module to produce a stable electrical output earlier than individual p and n-type Bi2Te3 modules.

The Role of Nrf2-ARE Signaling Pathway and Tatarinow Sweetflag Extract to Regulate the Acute Phase of Pilocarpine-Induced Epilepsy in Juvenile Rats.

To analyze the role of Nrf2-ARE signaling pathway in the regulation of the acute phase of pilocarpine-induced epilepsy in juvenile rats by Tatarinow Sweetflag Extract (TSE). One hundred and twenty SPF-grade Wistar male rats were were divided into five groups by random number table method, namely, normal group, model group, low-dose TSE group, high-dose TSE group, low-dose TSE + Nrf2 inhibitor Brusatol group (low-dose TSE + BRU group), and high-dose TSE + Nrf2 inhibitor Brusatol group (high-dose TSE + BRU group), with 20 rats in each group. The success rate of modelling in the model group, low-dose TSE group, high-dose TSE group, low-dose TSE + BRU group, high-dose TSE + BRU group were 60.00% (12/20), 65.00% (13/20), 65.00% (13/20), 70.00% (14/20), and 70.00% (14/20), respectively, showing no significant difference (P > 0.05). The latency and incidence of class IV and V, discharge amplitude as well as frequency of rats in the low- and high-dose TSE groups were lower than those in the model group (P < 0.05); the lipid peroxide and malondialdehyde concentrations in hippocampal tissues in the low- and high-dose TSE groups were lower than those in the model group (P < 0.05); The Nrf2, NQO-1 and HO- 1 protein and mRNA expression levels were increased in the low- and high-dose TSE groups compared with the model group (P < 0.05). The therapeutic effect of TSE in rats with acute epilepsy was satisfactory, and its mechanism of action may be related to activation of Nrf2-ARE signaling pathway to reduce the degree of oxidative stress.

Nonlinear evolution of space synthetic electric field in positive DC corona mode transition

Positive corona discharge in the air exists under several distinctive forms depending on DC voltage amplitude, including pulses or pulseless glow. Previous studies obtained the current and optical image characteristics of corona discharge through experiments. However, the synthesized electric field characteristics of the different corona modes have not been deeply studied by experiments, and lack of sufficient understanding of the effect of space charges. In this paper, electro-optical modulation technology is used to investigate the characteristics of the space synthetic electric field (SSE) for positive DC corona modes transition. The experimental results show the significant nonlinear evolution characteristics of the SSE and discharge modes transition with the increase of applied voltage. In the pulsed mode, the SSE first changes slowly and then increases sharply. As the applied voltage increases, the discharge mode transition from pulse mode to pulseless glow mode, while the SSE changes slowly. The electric field change rate in the sharp increase is 2–3 times that in the slow change. Dynamic accumulation behavior of space charges is the main reason for the nonlinear evolution of the SSE. When the pulse current starts, the discharge amplitude and frequency are low, and the ions are far away from the ionization region, which has little effect on the migration process of the high field strength region and subsequent ions. With the increase of the applied voltage, the continuous accumulation of positive ions enhances the migration of subsequent positive ions, thereby rapidly increasing the SSE. During the glow discharge mode, the generation and dissipation of space charges are close to dynamic equilibrium, and the fusion of multiple positive ion clouds will increase the SSE.

Revisiting Design Rules for Floating Metal

Electrostatic discharges (ESDs) from electrically isolated conductors (commonly called “floating metal”) were discovered to be sources of anomalies on early spacecraft. Ground tests demonstrated that discharges from floating metal were more severe and hazardous than discharges from equal areas of the dielectric film. This led to requirements to ground all thermal blanket layers. Charging and discharging of wires and coaxes were later discovered to be more severe if the conductors were ungrounded, which led to requirements to ground all unused and unterminated wires. Ground tests also showed that discharges from isolated conductors on printed circuit boards (PCBs) were also a potential risk despite the much lower flux levels inside these units. Subsequent tests showed that the peak voltage and energy of ESD transients induced in nearby PCB circuits scaled with the area of floating conductors. Based on those results, NASA HDBK 4002 and 4002A recommended limiting the area to 3 cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> (and to 0.3 cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> if the floating metal is on a PCB). (The recently released HDBK-4002B has removed these area guidelines.) Recent tests have shown that the peak voltage and delivered energy vary dramatically with the mode of discharge of the floating metal. Blow-off discharge amplitudes were similar to those observed in previous tests. But when the discharge punched through the insulator between the floating metal and underlying conductor, peak voltages and delivered energies were orders of magnitude higher. Given that modern designs employ multilayer circuit boards, the opportunity for punchthrough discharges is higher than that existed on the thick single-layer FR4 boards the HDBK 4002 guideline is based upon.

Influence of frequency on the partial discharge characteristics of biaxially oriented polypropylene film under nanosecond pulse voltage

Partial discharge (PD) is one of the key factors leading to premature insulation failure of film capacitors used in pulse power devices. To study the effect of frequency on the PD characteristics of biaxially oriented polypropylene (BOPP) film, a sphere-plate electrode was used to simulate defects of the air gap between the film layers. PD experiments of the BOPP film were carried out under 1, 10, 100, 500 Hz, and 1 kHz with a rising edge of 65 ns and a pulse width of 300 ns. The results show that the repetitive partial discharge inception voltage (RPDIV), the number of discharges, the rising stage discharge (RSD) amplitude, and the falling stage discharge (FSD) time-lag, all show an increase and then decrease with increasing pulse frequencies and reach a maximum value at a pulse frequency of 100 Hz. Moreover, the FSD discharge amplitude and the RSD discharge time-lag increase with an increasing pulse frequency. From the perspective of initial electron generation, the quantitative mathematical relationship between PD characteristics (RPDIV, PD amplitude, PD number, and PD time-lag) and frequency was established based on the Fowler–Nordheim field emission effect for the first time, which can reflect the influence of frequency on the memory effect and the development process of PD. The results can provide an experimental basis and a mechanistic explanation for the evaluation of PD characteristics for film capacitors under nanosecond pulse voltage.

Comparative Study on Partial Discharge Characteristics of Seven Accessory Defects Under Four On-Site Testing Voltages of a 10-kV Cable Line

Due to the increase in voltage levels and line lengths of power cables, the commonly used alternating current resonance (ACR) voltage is challenging to meet the growth rate of the capacitance of ultra-high-voltage cables for the on-site partial discharge (PD) tests. PD research on power-frequency-like voltages such as damped alternating current (DAC) voltage, very low-frequency sine wave (VLF-Sine) voltage, and very low-frequency cosine rectangular wave (VLF-CR) voltage, has important engineering value for evaluating the cable insulation conditions. In this paper, a PD test and measurement system of a 10 kV XLPE cable line with a 2 km length is established. Seven typical accessory defects are made artificially, including insulation hole, insulation screen tip, ring-cut tool mark, and stress cone installation dislocation defects at the terminals, and connector tip, conductive impurity, and stress cone installation dislocation defects at the joints. PD tests under four kinds of testing voltages of ACR, DAC, VLF-Sine, and VLF-CR are carried out to compare the PD inception voltages (PDIV), phase-resolved PD (PRPD) patterns, and PD location results of various defects. PD equivalence between power-frequency-like voltages and ACR is characterized by PDIV equivalent coefficient <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PDIV</sub> , PRPD pattern characteristic quantities and discharge amplitudes. The results show that DAC and VLF-Sine have an outstanding ability to detect and characterize the severity of PD. DAC and VLF-CR have a good ability to recognize the type of PD. And DAC, VLF-Sine and VLF-CR can accurately locate PD. This study provides an important reference for on-site cable defect diagnosis and PD assessment.

Characteristics of gut microbiota in male periadolescent rats with irritable bowel syndrome

Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disorder, however, its effect on gut microbiota during the periadolescent period remains unclear. In this study, our objective was to investigate the characteristics of gut microbiota in male periadolescent rats with IBS induced by neonatal maternal separation (NMS). We evaluated visceral sensitivity by electromyography (EMG), analyzed gut microbiota composition using 16S rDNA gene sequencing, and examined intestinal pathological changes between control and IBS-like groups. The IBS-like group had significantly higher discharge amplitude of the external oblique muscle of the abdomen during colorectal distension (CRD) at 40- and 60 mmHg pressures. We observed differences in gut microbiota composition, with an increase in Bacteroidetes abundance and a decrease in Firmicutes in IBS-like rats. Beta-diversity analysis revealed the gut microbiota of the IBS-like group displayed higher consistent, while that of the control group exhibited substantial variation. Linear discriminant analysis effect size (LEfSe) detected 10 bacterial taxonomic clades showing statistically significant differences (7 increased and 3 decreased) in the IBS-like group. Functional analysis revealed that aminoacyl-tRNA biosynthesis and fatty acid biosynthesis were significantly altered, leading to changes in gene expression. Our findings demonstrate a definite correlation between gut microbiota dysbiosis and IBS during the male periadolescent period, with Alloprevotella and Bacteroide positively associated with high risk of IBS. The effects of specific bacterial genera may provide new insights for the development of treatments for IBS.

Numerical simulation of the argon dielectric barrier discharge driven by dual frequency at atmospheric pressure

Argon dielectric barrier discharge driven by the dual frequency at atmospheric pressure has been investigated by a 1D fluid model. Temporal evolutions of voltage and charge density on dielectric surface, fluxes of electrons and ions on the surface, the spatiotemporal distribution of electron generation rate, and the spatial distribution of electron density are studied with various low-frequency (LF) voltages. Minimum sustained discharge amplitude of high frequency (HF) voltage and spatiotemporal mean electron density over one LF period varying with sheath voltage (α → γ) are also discussed. Results show that in α mode, the electron flux on the dielectric surface decreases significantly when the LF voltage amplitude is lower while the ion flux is less affected. The positive charge density on the surface increases, causing the surface voltage waveform to shift upward. When the LF voltage amplitude is 40 V and that of HF voltage is 87 V, the positive and negative values of voltage amplitude of dielectric surface are 182 and 32 V. As the LF voltage amplitude increases further, the sheath formation time is significantly delayed and the discharge terminates, and the rate of electron generation decreases significantly. The discharge is extinguished when the amplitude of LF voltage is 68 V while it regains when the amplitude reaches up to 750 V. In γ mode, when the amplitude of HF voltage reaches or exceeds its minimum sustained discharge value, the generation and distribution of electrons are almost unaffected by the amplitude of LF voltage.

Effect of Polycyclic Aromatic Compounds on Electrical Treeing Growth in XLPE Insulation

This article focuses on the effect of polycyclic aromatic compounds (PACs) on the electrical tree of cross-linked polyethylene (XLPE) insulation for high-voltage (HV) cables. The XLPE insulation samples with or without PACs are prepared for electrical treeing degradation at constant and cyclic temperatures. The results show that the growth of the electrical tree within the XLPE/PACs insulation is retarded. The partial discharge (PD) amplitudes of XLPE/PACs insulation are significantly decreased during the treeing process compared to XLPE insulation. Furthermore, under cyclic temperature conditions, the tree growth of XLPE/PACs composites stagnates as the temperature decreases from 90 °C to 25 °C. Even when it rebounds to 90 °C, the treeing degradation of XLPE/PACs insulation is still retarded, resulting from a significant weakness of PD. The results show that the XLPE/PACs composites exhibit a greater electrical treeing resistance. Based on density functional theory (DFT), analysis of the excitation characteristics and density of states (DoS) reveals that the PACs absorb photon energy to prevent damage to insulation. In contrast, the excited PACs result in a cross-linking reaction to XLPE and introduce electron and hole traps, which capture hot electrons. The cross-linking product acts as localized states of electron traps and hole traps, which capture the high energy carriers during treeing. In summary, the PACs retard the growth of electrical trees and improve the insulation performance.

Effects of Mud Supply and Hydrodynamic Conditions on the Sedimentary Distribution of Estuaries: Insights from Sediment Dynamic Numerical Simulation

Estuaries are important sediment facies in the fluvial-to-marine transition zone, are strongly controlled by dynamic interactions of tides, waves, and fluvial flows, and show various changes in depositional processes and sediment distribution. Deep investigations on the sediment dynamic processes of the sand component of estuaries have been conducted; however, the understanding of how mud supply affects estuaries’ sedimentary characteristics and morphology is still in vague. Herein, the effects of mud concentration, mud transport properties, fluvial discharge, and tidal amplitude on the sedimentary characteristics of an estuary were systematically analyzed using sedimentary dynamic numerical simulation. The results show that the mud concentration has significant effects on the morphology of tidal channels in estuaries, which become more braided with a lower mud concentration, and straighter, with reduced channel migration, with a higher mud concentration. The mud transport properties, namely, setting velocity, critical bed shear stress for sedimentation, and erosion, mostly affect the ratio between the length and width (RLW) of the sand bar; a sheet-like sand bar with a lower RLW value develops in the lower settling velocity, while there are obvious strip shaped bars with a high RLW value in the higher settling velocity case. Moreover, the effects of hydrodynamic conditions on sedimentary distribution were analyzed by changing the tidal amplitudes and fluvial discharges. The results show that a higher tidal amplitude is often accompanied by a stronger tidal energy, which induces a more obvious seaward progradation, while a higher fluvial discharge usually yields a higher deposition rate and yields a greater deposition thickness. From the above numerical simulations, the statistical characteristics of tidal bars and mud interlayers were further obtained, which show good agreement with modern sedimentary characteristics. This study suggests that sedimentary dynamic numerical simulation can provide insights into an efficient quantitative method for analyzing the effects of mud components on the sediment processes of estuaries.

Lesion-induced sprouting promotes neurophysiological integration of septal and entorhinal inputs to granule cells in the dentate gyrus of rats

Axonal sprouting of dentate gyrus (DG) afferents after entorhinal cortex (EC) lesion is a model preparation to assess lesion-induced functional reorganization in a denervated target structure. Following a unilateral EC lesion, the surviving contralateral entorhinal projection, termed the crossed temporodentate pathway (CTD), and the heterotypic septal input to the DG, the septodentate pathway (SD), undergo extensive axonal sprouting. We explored whether EC lesion alters the capacity of the SD pathway to influence CTD-evoked granule cell excitability in the DG. We recorded extracellular field excitatory postsynaptic potentials (fEPSPs) after CTD stimulation alone and paired SD-CTD stimulation. Male rats were given unilateral EC lesions or sham operations; evoked fEPSPs in the DG were recorded at 4-, 15-, and 90-days post-entorhinal lesion to assess functional reorganization of the CTD and SD pathways. We found significantly increased fEPSP amplitudes in cases with unilateral lesions compared to sham-operates at 15- and 90-days post lesion. Within each time point, paired SD-CTD stimulation resulted in significantly depressed fEPSP amplitudes compared to amplitudes evoked after CTD stimulation alone and this effect was solely seen in cases with EC lesion. In cases where granule cell discharge was observed, SD stimulation increased discharge amplitude elicited by the CTD stimulation at 90-days postlesion. These findings demonstrate that synaptic remodeling following unilateral cortical lesion results in a synergistic interaction between two established hippocampal afferents that is not seen in uninjured brains. This work may be important for models of neurodegenerative disease and neural injury that target these structures and associated hippocampal circuitry.

Allopurinol and ellagic acid decrease epileptiform activity and the severity of convulsive behavior in a model of status epilepticus.

During status epilepticus, severe seizures can occur, generating recurrent cycles of excitotoxicity and oxidative stress that cause neuronal damage and cell death. The administration of agents with antioxidant properties represents a therapeutic alternative aimed at reducing the severity of status epilepticus and mitigating the neurobiological consequences that precede them. The objective of this work was to evaluate the antiseizure effect of the antioxidants allopurinol (ALL) and ellagic acid during status epilepticus induced by pilocarpine (PILO). Male Wistar rats (200-250 g) were injected with ALL (50 mg/kg) or ellagic acid (50 mg/kg), 30 min before PILO administration (pretreatment) or 60 min after the beginning of status epilepticus, to evaluate the antiseizure effect of these drugs on epileptiform activity and convulsive behavior. ALL or ellagic acid administration before or after PILO significantly decreased the epileptiform activity and the severity of convulsive behavior. Better efficacy was observed when the drugs were administered as a pretreatment, increasing the latency time of the appearance of status epilepticus from 27.2 ± 2.6 to 45.8 ± 3.31 min, and significantly reducing the amplitude of epileptiform discharges by 53.5% with ALL and 68.9% with ellagic acid. The antioxidants ALL and ellagic acid showed an antiseizure effect, representing an alternative to reduce epileptiform activity and severity of convulsive behavior during status epilepticus, an effect that may be used as adjuvants to mitigate or reduce oxidative damage processes.

Partial Discharge Measurement and Analysis of Transformer Under Oscillating Lightning Impulse Voltage

Oscillating lightning impulse (OLI) voltage is recommended for on-site testing due to its high generation efficiency. In this article, partial discharge (PD) characteristics under field impulse voltage waveforms are investigated. The experiment is carried out on a scaled transformer model with a protrusion defect inside as the PD source. Both oscillating and standard lightning impulse (SLI) voltages are acquired as test waveforms. Main discharges and reverse discharges are detected simultaneously under both OLI and SLI voltage. The increasing applied voltage amplitude advances the main discharge and enlarges its amplitude, and it also prolongs the duration of the reverse discharge and increases the number. The amplitude of main discharge is related to the PD voltage, while that of reverse discharge depends on the dynamic variation of the impulse voltage. Since OLI voltage contains multiple rising edges during the oscillation period, more PDs are excited. A disruptive effect (DE) model is extended for the PD analysis to show the oscillation effect on the PD distribution. The OLI test with PD measurement performed on a 220-kV transformer proves that PD detection during impulse voltage withstand test reflects more detailed information that can be used for early diagnosis of power transformers.

ОСОБЛИВОСТІ ПЕРЕХІДНИХ ПРОЦЕСІВ У КОЛАХ ДРУГОГО ПОРЯДКУ З НЕЛІНІЙНОЮ МОДЕЛЛЮ ІСКРОЕРОЗІЙНОГО НАВАНТАЖЕННЯ В УМОВАХ ПРИМУСОВОГО ОБМЕЖЕННЯ ЇХНЬОЇ ТРИВАЛОСТІ

In the Mathlab Simulink software environment a model of a second-order discharge-pulse system with a nonlinear de-scription of the equivalent electrical resistance of a spark-erosion load was created. Under conditions of forced limita-tion of the duration of discharge pulses for a series of values of the inductance and capacitance of the discharge circuit, as well as the initial conditions in them, transients in the system are calculated. In groups of modes with fixed values of the initial voltage on the working capacitor and in groups of modes with fixed values of voltage amplitude of the free discharges on load, the dependences on duration of the discharge pulses of their energy, pulse power in the load, and the rate of its change are plotted and analyzed. It is shown that in both groups of modes for each set of parameter val-ues of: the duration of the discharge pulses, the capacitance of the working capacitor and the initial voltage on it, there is a value of the inductance of the discharge circuit, which provides the highest values of the rate of change of the pulse power in the load. In the groups of modes with fixed values of the voltage amplitude of free discharges on the load, for the set of parameters described above, there are also values of the discharge circuit inductance that provide the highest values of energy and pulse power in the load. For three values of the inductance of the discharge circuit, the problems of increasing the above pulse parameters are graphically solved. References 27, figures 11.

Neural inputs from spinal motor neurons to lateralis vastus muscle: Comparison between sprinters and nonathletes.

The adaptation of neural contractile properties has been observed in previous work. However, the neural changes on the motor unit (MU) level remain largely unknown. Voluntary movements are controlled through the precise activation of MU populations. In this work, we estimate the neural inputs from the spinal motor neurons to the muscles during isometric contractions and characterize the neural adaptation during training by comparing the MU properties decomposed from sprinters and nonathletes. Twenty subjects were recruited and divided into two groups. The high-density surface electromyography (EMG) signals were recorded from the lateralis vastus muscle during the isometric contraction of knee extension and were then decomposed into MU spike trains. Each MU’s action potentials and discharge properties were extracted for comparison across subject groups and tasks. A total of 1097 MUs were identified from all subjects. Results showed that the discharge rates and amplitudes of MUAPs from athletes were significantly higher than those from nonathletes. These results demonstrate the neural adaptations in physical training at the MU population level and indicate the great potential of EMG decomposition in physiological investigations.

Thunder acoustic signature for channel reconstruction in triggered lightning

There are few reports on the near-field acoustic signals corresponding to lightning return strokes. One rocket-triggered lightning flash, which contains 13 return strokes, initial continuous current (ICC) processes, and abundant M-components, was observed in the summer of 2018 and reported in this study. The complete near-field acoustic pressure signals initiated by the flash were recorded and analyzed. It is found that the near-field acoustic pressure signals from each return stroke are composed of the first arrived N-shape shock waveform and the subsequent low-frequency oscillating waveforms. The characteristic of the acoustic waveforms has been parametrically defined and quantitatively analyzed, with a comprehensively acoustic-electrical correlation investigation. The acoustic pressure signals from intensive ICC processes and M-component pulses with different discharge intensities are also discussed. It is found that the too-close time interval between M-component and previous current pulses would affect the generation and measurement of the acoustic pressure waveforms from the M-component, even though the discharge amplitude is competitive and the wavefront is fast. The same phenomenon has also been observed in the acoustic signals from a return stroke with a too close interval from the previous pulse. The acoustic source localization with great accuracy for lightning channel reconstruction was realized based on the measured acoustic signals. The reconstructed channel structure agrees with that of the synchronously captured optical image. The study of the characteristics of acoustic signals from lightning discharge contributes to the recognition of thunder signals, source localization for channel reconstruction, and understanding of the lightning discharge process.