Voltage Gradient Research Articles

Influence of mild electric field (MEF) on polyphenol oxidase and quality attributes of pineapple juice during ohmic heating

Fresh pineapple juice was ohmically heated up to 80 ± 2 °C (held for 1 min), followed by cooling. The voltage gradient (VG) of 16 V/cm was kept constant for the come-up period to maintain an identical thermal history. The effect of VG on Polyphenoloxidase (PPO), color, hydroxymethylfurfural (HMF), and total phenolic content (TPC) was evaluated by maintaining 16–36 V/cm at the temperature (80 ± 2 °C). The PPO activity was reduced to 50.06 and 56.67% by hot water (HWT) and ohmic heating (OH) (16 V/cm) treatment, respectively. PPO inactivation showed exponential (k = −0.342; R2 = 0.965) relationship with the VG (16–36 V/cm). The a* value (redness) increased with the VG, whereas the b* (blue-yellow) and hue value remained unchanged up to 16-32V/cm. Both OH and HWT treatments caused an increase in HMF content from 0.145 to 0.351 and 0.233 mg/100 mL, respectively. The TPC content reduced by 18% in HWT, while only 7–10% losses were observed in OH within 16–24 V/cm. The development of HMF with VG was best expressed by the polynomial model (R2 = 0.976–0.994), whereas the TPC degradation followed quadratic relation (R2 = 0.856 ± 0.906). Therefore, it was observed that VG plays an important role in OH-based enzyme inactivation method for pineapple juice.

Low-cost gradient amplifiers for small MRI systems

We describe low-cost gradient amplifiers for small MRI systems, such as those based on small/medium permanent magnets. The requirements for MRI gradient amplifiers are quite similar to those of modestly priced audio stereo power amplifiers. Such amplifiers for sound service can be modified to be DC coupled, extending their response down to zero frequency, as needed for MRI gradient service. We describe such modifications to one unit (Samson Servo 600) and mention a commercially available modification of another. The 600 is capable of an output greater than ±8 A and ±60 V, much greater than our needs for a greenhouse MRI. Audio amplifiers can be used this way as controlled voltage (CV) gradient amplifiers, with acceptable performance because the gradient coils typically have short L/R time constants. Superior performance can be had by using a controlled current (CC) “front end”; the circuit of our simple front end is included. The complete 3-axis CC system costs about $1200.

Assisted ohmic heating extraction of pectin from pomegranate peel

Pomegranate peel is rich in various compounds such as pectin. The aim of this study was to first, find the optimal conditions for extracting pomegranate pectin by ohmic heating method and then, to compare the properties of this pectin with pectin extracted under optimal conditions by conventional acidic method. With conventional acidic method, the optimal extractor acid, pH and solid to solvent ratio were determined, they were hydrochloric acid, 1.5 and 1:40, respectively, and these results were generalized to ohmic heating extraction condition. Then, the effects of voltage gradient and time, during ohmic heating on the yield and galacturonic acid, were studied using the response surface methodology (RSM). According to the findings, the optimal conditions for the voltage gradient and time were 10 V/cm and 18 min, respectively. Extraction yield and galacturonic acid percentage were 8.16% and 82.86% in ohmic method and 8.93% and 73.84% in conventional method, respectively. As it can be seen, the galacturonic acid content of the pectin extracted under ohmic heating were significantly higher. The study on different pomegranate peel size showed that in ohmic heating even with bigger size of particle, the yield remained constant.

The exposure of OPFRs in fish from aquaculture area: Backward tracing of the ecological risk regulation

In this study, we backward traced and controlled the pollution of organophosphorus flame retardants (OPFRs) in aquaculture areas from the standpoints of terminal treatment, migration and transformation resistance, and source molecular substitution technology. A regulatory plan to considerably reduce the combined biotoxicity of fish exposed to OPFRs in aquaculture areas and significantly improves the biodegradation of sewage treatment and the efficiency of soil plant-microorganism combined remediation was formulated. Environmentally friendly alternatives of OPFRs were designed. The supplementation scheme of aquatic feed significantly alleviates the toxicity risk of fish exposure to OPFRs in aquafarm (reduced by 121.02%). The regulatory scheme of external stimulus to enhance the biodegradation of OPFRs in wastewater treatment process included an H2O2 concentration of 400 mg/L, voltage gradient of 1.5 V/m, and pH of 6.5 can improve the degradation capacity of OPFRs molecules by 88.86%. The degradation of OPFRs can be enhanced by plant-microorganism combined remediation (up to 98.64%) by growing plants whose primary function is phytoextraction in soils dominated by Sphingopyxis sp. and Rhodococcus sp. A 3D-QSAR pharmacophore model based on apoptosis toxicity, mitochondrial dysfunction, oxidative stress response, reproductive, neurotoxicity, gill-inhalation combined toxicity of fish exposed to OPFRs in aquafarm was fabricated. The recommended aquatic feed scheme and the control scheme of enhanced degradation of OPFRs by sewage treatment and soil environment had better applicability for the new-designed OPFRs substitution molecules (the maximum combined toxicity/degradation is reduced/increased by 75.46% and 63.24%, respectively). In this paper, a technical scheme of OPFRs terminal treatment, process regulation, and source control was applied as a cradle-to-grave approach to reduce the ecological toxicity risk of fish exposed to OPFRs in aquaculture areas providing theoretical support for the realization of OPFRs environmental pollution control.

Abstract 14261: Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia: A Standardized Mapping System Protocol

Introduction: according to European guidelines, ablation has become the treatment of choice in patients with symptomatic atrioventricular nodal reentry tachycardia (AVNRT). Despite the high procedure success rate, anatomical variations can affect the outcome in terms of relapses and complications. As recently demonstrated, low-voltage bridge visualization allows low pathway identification and therefore a new ablation strategy. Hypothesis: our purpose was the validation of standardized ablation protocol within the low-voltage bridge area. Methods: 70 consecutive patients with inducible AVNRT were evaluated and a three-dimensional voltage map of the right atrial septum and Koch Triangle was constructed by means of contact mapping. Ablation site was identified as the low-voltage area below the His bundle, adjusting the high-voltage slider to 1,5 mV and dynamically adjusting the slider of low-voltage. Radio-frequency energy (with an average number of nine lesions per patient) was then delivered within this area until the appearance of junctional beats. The results were tested at the end of the procedures and during the observational period (the mean follow-up was 10,5 months). Results: the slow pathway was identified by the low-voltage bridge in 60 patients (85,6%) and in these patients, the target lesions in that area finally prevented induction of AVNRT in 100% of cases. A zero-fluoroscopy approach was possible for 50 patients (83%). Compared with standard AVNRT ablation, no complications as well as no statistical differences in terms of total procedure time were observed (p=0,056). 59 patients (98%) had no relapses during the follow-up. Conclusions: voltage gradient mapping successfully targeted the slow pathway in most of our cases. Lesions on the voltage bridge led to effective ablation of AVNRT and to a drastic x-ray exposure reduction in the absence of acute or long-term complications.

Degradation of Dibutyl Phthalate Plasticizer in Water by High-Performance Iro2-Ta2O5/Ti Electrocatalytic Electrode

Dibutyl phthalate (DBP) in the presence of a wastewater system is harmful to the environment and interferes with the human’s endocrine system. For wastewater treatment, DBP is very difficult to be decomposed by biotechniques and many catalytic processes have been developed. Among them, the electrocatalytic oxidation (EO) technique has been proven to possess high degradation efficiency of various organic compounds in wastewater. In this study, an electrocatalytic electrode of iridium-tantalum/titanium (IrO2-Ta2O5/Ti) was employed as the anode and graphite as the cathode to decompose DBP substances in the water. According to experimental results, the high removal efficiency of DBP and total organic carbon (TOC) of 90% and 56%, respectively, could be obtained under a voltage gradient of 10 V/cm for 60 min. Compared with other photocatalysis degradation, the IrO2-Ta2O5/Ti electrode could shorten about half the treatment time and electric power based on the same removal efficiency of DBP (i.e., photocatalysis requires 0.225~0.99 KWh). Results also indicated that the production of hydroxyl radical (•OH) in the electrocatalytic electrode played a key role for decomposing the DBP. Moreover, the pH and conductivity of water containing DBP were slightly changed and eventually remained in a stable state during the EO treatment. In addition, the removal efficiency of DBP could still remain about 90% after using the IrO2-Ta2O5/Ti electrode three times and the surface structure of the IrO2-Ta2O5/Ti electrode was stable.

Voltage compartmentalization in dendritic spines in vivo.

Dendritic spines mediate most excitatory neurotransmission in the nervous system, so their function must be critical for the brain. Spines are biochemical compartments but might also electrically modify synaptic potentials. Using two-photon microscopy and a genetically encoded voltage indicator, we measured membrane potentials in spines and dendrites from pyramidal neurons in the somatosensory cortex of mice during spontaneous activity and sensory stimulation. Spines and dendrites were depolarized together during action potentials, but, during subthreshold and resting potentials, spines often experienced different voltages than parent dendrites, even activating independently. Spine voltages remained compartmentalized after two-photon optogenetic activation of individual spine heads. We conclude that spines are elementary voltage compartments. The regulation of voltage compartmentalization could be important for synaptic function and plasticity, dendritic integration, and disease states.

SSM-based electrophysiology, a label-free real-time method reveals sugar binding & transport events in SGLT1

Here, we present a solid-supported membrane (SSM)-based electrophysiological approach to study sugar binding and Na+/glucose cotransport by SGLT1 in membrane vesicles. SSM-based electrophysiology delivers a cumulative real-time current readout from numerous SGLT1 proteins simultaneously using a gold-coated sensor chip.In contrast to conventional techniques, which mainly operate with voltage steps, currents are triggered by sugar or sodium addition. Sugar concentration jumps in the presence of sodium lead to transport currents between 5 and 10 nA. Remarkably, in the absence of sodium (i.e. no transport), we observed fast pre-steady-state (PSS) currents with time constants between 3 and 10 ms. These PSS currents mainly originate from sugar binding. Sodium binding does not induce PSS currents. Due to high time resolution, PSS currents were distinguished from transport and eventually correlated with conformational transitions within the sugar translocation pathway.In addition, we analyzed the impact of driving forces on transport and binding currents, showing that membrane voltage and sodium concentration gradients lead to an increased transport rate without affecting sugar binding kinetics. We also compared Na+/sugar efflux with physiologically relevant influx and found similar transport rates, but lower affinity in efflux mode.SSM-based electrophysiology is a powerful technique, which overcomes bottlenecks for transport measurements observed in other techniques such as the requirement of labels or the lack of real-time data. Rapid solution exchange enables the observation of substrate-induced electrogenic events like conformational transitions, opening novel perspectives for in-depth functional studies of SGLT1 and other transporters.

High‐performance ZnO varistor ceramics prepared by arc‐induced flash sintering with low energy consumption at room temperature

The development of ultra-high voltage transmission lines requires a ZnO arrester with excellent electrical response and high voltage gradient. Compared with conventional preparation methods, flash sintering allows fast production of novel high-performance ZnO varistor ceramics with low energy consumption and controlled grain growth. Herein, ZnO varistor ceramics were prepared using the flash sintering method at an air pressure of 21 kPa for 60 s at 25°C. The results showed that the flash-sintered samples had fine grains and reduced loss of volatile elements. Moreover, the voltage gradient, leakage current density, and non-linear coefficient of the flash-sintered varistor ceramics were significantly improved compared with those of conventionally sintered samples. Owing to the short preparation time and absence of a heating process, the energy consumption of the proposed flash sintering method was significantly reduced to 10% of that by conventional sintering. The proposed method is a promising approach for the preparation of ZnO arresters with excellent electrical properties and serves as an effective method that realises energy saving and emission reduction.

Experimental investigation on flashover characteristics of hollow porcelain insulator under extreme rainfall

This paper deals with the effects of rain conditions and shed parameters on flashover characteristics of hollow porcelain insulators through conducting artificial rain tests under extreme rainfall. And the effects of water droplet deformation on inter-shed discharge are examined especially. The results show that the rain flashover voltage gradient along the insulation height falls with the rise of rainfall intensity due to the increase in the maximum deformation length of water droplet, which can bring about two kinds of inter-shed discharge modes under different rainfall intensity. The fact that the maximum deformation length of water droplet is barely influenced by rainwater conductivity determines the consistency of inter-shed discharge modes under different rainwater conductivity. The rain flashover voltage gradient along the insulation height decreases with the rising rainwater conductivity since the insulator surface resistance falls with rainwater conductivity. Moreover, shed spacing can influence inter-shed discharge mode, which is reflected in the diverse direction of the discharge propagation at water droplet end under different shed spacing. The length of air gap on the breakdown path increasing improves rain flashover voltage gradient along the insulation height as shed spacing rises. However, the inter-shed discharge mode is independent of shed overhang. The rain flashover voltage gradient along the insulation height rising with shed overhang is attributed to the increase in the leakage distance along the shed surface. This work clarifies the inter-shed discharge mode of rain flashover and can provide valuable support for the shed design of insulators in extreme rainfall areas.

Electrokinetic remediation of Cd-contaminated soil using low voltage gradients coupled with array adsorption zone and polarity exchange

Soil Cd pollution is a threat to the global ecological environment. Electrokinetic remediation (EKR) generally uses strong electric fields to obtain high removal efficiency, which leads to a series of side reactions and high energy consumption. EKR using low-voltage gradients showed weak migration of Cd and low remediation efficiency. Herein, to develop an effective enhanced EKR technology using low voltage gradient (0.2 V·cm−1), array adsorption zone and polarity exchange were applied simultaneously. Five experiments were conducted to determine the effect of polarity exchange, array adsorption zone and their combination on Cd removal when EKR was carried out at 0.2 V·cm−1. Results showed that the combined use of the array adsorption zone and polarity exchange achieved optimal remediation and average Cd removal efficiency was 83%. Moreover, the reciprocating motion of Cd caused by polarity exchange is no longer a side effect. In the wheat cultivation experiment, the Cd concentration of wheat root, stem and leaf decreased by 86%, 93% and 95% after Cd was removed by EKR coupled with array adsorption zone and polarity exchange. The 30-day energy consumption is 7.72 kWh·m−3, which is far lower than that of other enhancement methods. The present work proposes an effective EKR technology working at low voltage for Cd-contaminated soil.

Efficacy of Ohmic Vacuum Concentration for orange juice concentrates and their physicochemical properties under different voltage gradients

The efficacy of ohmic vacuum concentration (OVC) was evaluated for the production of value-added orange juice concentrate under different voltage gradients. OVC enables the evaporation of moisture in fruit juice at low temperatures under a vacuum. An OVC system was customized using an ohmic cell, vacuum chamber, vacuum pump, and pressure regulator. During OVC treatment, orange juice extract was ohmically heated to 66 °C using different voltage gradients (15, 20, 25, and 30 V/cm) under 27 kPa vacuum. The highest concentration of OVC was 22 min, producing 2 kg water/kg dry solid orange concentrate. However, it took 40 min to produce the same concentration using ohmic atmospheric concentration (OAC) treatment. OVC minimized the depolymerization of pectin at lower concentrations and produced a thicker orange concentrate than that by OAC. OVC also enabled a slower concentration time in which the orange concentrate was exposed to less thermal abuse. OVC did not induce discoloration or degradation of vitamin C content because the juice extract was concentrated at low temperatures for a short time. This study showed the potential of OVC to produce value-added fruit juice concentrates.

Pollution Flashover Characteristics of Composite Crossarm Insulator with a Large Diameter

The composite crossarm insulator differs greatly from the suspension insulator in structure and arrangement. This study aims to determine the pollution flashover characteristics of composite crossarm insulators under different voltage grades. Four types of AC composite crossarm insulators with diameters ranging from 100 mm to 450 mm are subjected to artificial pollution test, and then the effects of the surface hydrophobicity state of silicone rubber, core diameter, umbrella structure, arrangement, and insulation distance on the pollution flashover voltage of the composite crossarm insulators are analyzed. Under the pollution grade 0.2/1.0 mg/cm2 and voltage grade from 66 kV to 1000 kV, if the silicone rubber surface changes from HC5 to HC6, the pollution flashover voltage of the composite crossarm insulator will increase by 13.5% to 21.0% compared with the hydrophilic surface. If the core diameter changes from 100 mm to 300 mm, the pollution flashover voltage gradient decreases with the increase in core diameter; if the core diameter changes from 300 mm to 450 mm, the pollution flashover voltage gradient increases with core diameter. Under the same insulation height and core diameter, the umbrella structure will have a certain impact on pollution flashover voltage by up to 1.7% to 5.4%. Under the horizontal arrangement, the pollution flashover voltage can increase by 10.5% to 12.1% compared with that under the vertical arrangement. Under the hydrophilic surface and weak hydrophobicity state, the pollution flashover voltage has a linear relationship with the insulation distance. The above results can provide a reference for the structural design and optimization of the composite crossarm insulator.

Single-step recovery of pectin and essential oil from lemon waste by ohmic heating assisted extraction/hydrodistillation: A multi-response optimization study

The main products obtained from citrus wastes are pectin and essential oil. In this work, ohmic heating assisted extraction/hydrodistillation (OHAE/H) was applied for the simultaneous recovery of pectin and essential oil from lemon waste. Optimum OHAE/H conditions to maximize the yield of pectin and essential oil were determined with response surface methodology. Three independent variables, namely liquid to solid ratio (w:v), extraction/hydrodistillation time (min) and voltage gradient (V/cm) were varied to obtain maximum pectin and essential oil yield. Optimum OHAE/H conditions were determined as 8.7:1 liquid to solid ratio, 58.4 min extraction/hydrodistillation time and 14.2 V/cm voltage gradient. The predicted pectin and essential oil yields at optimum conditions were 16.58 and 3.62 g/100 g lemon waste, respectively. Data analysis showed that all of the independent variables significantly affected the pectin and essential oil yield. In the verification study, close agreement was found between predicted and experimental values. Conventional heating extraction/hydrodistillation (CHE/H) were conducted to evaluate the effectivity of OHAE/H. With OHAE/H process, the yields of the pectin and essential oil were significantly increased when compared to CHE/H. Limonene concentration of the essential oil produced with OHAE/H was higher than the essential oil produced by CHE/H. Results demonstrate that the single-step OHAE/H could be an effective method for simultaneous extraction and hydrodistillation of pectin and essential oils.

Chelating surfactant N-lauroyl ethylenediamine triacetate enhanced electrokinetic remediation of copper and decabromodiphenyl ether co-contaminated low permeability soil: Applicability analysis

In this study, chelating surfactant N-lauroyl ethylenediamine triacetate (N-LED3A) was used as strengthening agent for electrokinetic (EK) remediation of copper (Cu) and decabromodiphenyl ether (BDE209) co-contaminated low permeability soil. The results indicated that negligible amount of N-LED3A would be adsorbed on the experimental soil. The synchronous elution efficiencies (SEEs) of Cu and BDE209 had reached 65.4% and 49.9%, respectively, when the concentration of N-LED3A was 4000 mg/L, and they kept almost unchanged as the concentration of N-LED3A further increased. Meanwhile, the optimal SEEs were obtained at the pH condition within 6–8. The removal efficiencies of Cu (55.3%–65.8%) and BDE209 (31.4%–46.4%) would be increased with the applied voltage gradient and concentration of N-LED3A. In addition, BDE209 and Cu contaminants were also detected in the catholyte and anolyte, respectively, and their concentrations still showed an uptrend by the end of the experiments. While in the control experiments, the removal efficiency of Cu was in the range of 18.2%–23.6%, and almost no BDE209 was migrated out. The electric current would be increased with N-LED3A concentration increased, further resulting in the enhancement of cumulative electro-osmotic flow (EOF). However, the increment of EOF was limited after an 8-day treatment due to the declined capacity of the soil water supply, and the removal efficiency of BDE209 did not change proportionally to the cumulative EOF as a consequence. The accumulated (21 days) energy consumption under the optimal operation conditions (voltage gradient 1 V/cm, N-LED3A 1 g/L) was 377.28 KWh/m3. Efficiently synchronous removal of BDE209 and Cu could be achieved by the N-LED3A enhanced EK technique, exhibiting a promising application potential in the organic pollutant and heavy metal co-contaminated soil remediation.

Microstructure and Electrical Properties of In2O3, La2O3 and Ga2O3 Doped ZnO-Bi2O3-MnO2-SiO2-TiO2 Varistor Ceramics

ZnO-Bi2O3-MnO2-SiO2-TiO2 varistor ceramics with addition of X2O3 (X = In, La, Ga) were manufactured through the conventional solid-state method and their phase transformation, microstructure, band gap, and electrical properties were investigated by X-ray diffractometer, Scanning electron microscopy, Fourier transform infrared spectroscopy, and solid UV absorption spectrometry, respectively. The results show that ZnO-Bi2O3-MnO2-SiO2-TiO2-0.15 mol% X2O3 ceramics can be successfully produced at a very low temperature of 875 °C. When X2O3, especially Ga2O3, is doped into ZnO varistors, the grain sizes of specimens are refined. The grain size of ZnO-based varistor ceramics with Ga2O3 doping decreases obviously from 4.31 to 3.10 μm, and the voltage gradient increases from 763.1 to 1047.5 V mm−1. The nonlinear coefficient of ZnO-based varistor ceramics with In2O3 doping increases from 26.5 to 36.7.

Evaluation of an ohmic assisted vacuum evaporation process for orange juice pulp

An ohmic assisted vacuum evaporation (OAVE) processes was used to concentrate orange juice from 11.4% total soluble solid content (TSSC) to 42% TSSC by applying 13 V/cm constant voltage gradient at different temperatures. The evaporation temperatures were adjusted to 100 °C, 85 °C, 75 °C and 65 °C by setting absolute system pressures of 101.32 kPa, 58 kPa, 39 kPa and 25 kPa, respectively. The total time for the processes, including heating and evaporation, was 34, 40, 48, and 54 min for 100, 85, 75, and 65 °C, respectively. As the evaporation temperature increased, the applied energy required for phase change decreased while maximum current values increased from 0.6 A at 65 °C to 2.52 A at 100 °C. During any given run, the current value increased as the orange juice pulp heated up, but then decreased after it began to boil, leading to a reduction in the rate of heat generation. Increasing evaporation temperature has a positive effect on evaporation rates, energy efficiency, specific water removal ratio (SWRR), exergy efficiency, and Improvement Potential (IP) (p < 0.05). The reduced energy requirement with higher temperature is partially due to reduced work from the vacuum pump at the higher absolute pressure.

An adaptive DC line fault recovery strategy for LCC-HVDC system based on voltage gradient

Due to the lack of characteristic variables to determine whether the fault point persists during DC-line fault recovery in a Line-commutated-converter High Voltage Direct Current (LCC-HVDC) system, it is difficult to distinguish transient and permanent faults. Concerning this problem, an adaptive DC-line fault recovery strategy based on voltage gradient is proposed. Firstly, the variation of the topology of DC system after phase shift is analyzed, and the calculation model of voltage at the outlet of inverter station is built, thus the expression of voltage at the outlet of inverter station containing parameters of fault location, fault resistance and fault duration is obtained. On this basis, characteristics of the gradient of voltage at the outlet of the inverter station are analyzed, i.e. its value monotonically decreases and quickly attenuates to 0 in the case of permanent fault, and abruptly drops below 0 the moment fault disappears in the case of transient fault. According to the characteristics of the voltage gradient, the criterion for the identification of transient and permanent faults is constructed, thus adaptive DC-line fault recovery is realized. Finally, simulation tests in RT-LAB verify that, the proposed method can correctly identify the fault nature of permanent and transient faults on the DC line and realize adaptive fault recovery, unaffected by the fault location, fault resistance and fault duration.

In situ removal of cadmium by short-distance migration under the action of a low-voltage electric field and granular activated carbon

Cd pollution in soil is a global environmental issue of great concern. The secondary release and low removal rate of Cd are obstacles to the use of adsorption techniques. To develop a sustainable and effective remediation technique, low-voltage direct current (DC) and granular activated carbon (GAC) were applied for in situ Cd removal. The results showed that a low-voltage gradient was more favourable than a high-voltage gradient for Cd removal. A voltage gradient of 0.2 V cm−1 acted as a driving force for Cd migration while limiting the side effects caused by DC. As an auxiliary enhancement measure, polarity exchange was effective in maintaining uniform distributions of soil moisture and temperature as well as a stable pH while improving Cd removal by weakening inhibition caused by OH− generated at the cathodes. The average removal rates of total and bioavailable Cd were 61.05% and 76.96%, respectively. The potential mobility of Cd in soil was assessed by the mobility factor (MF). The MF was lowered from 42.66% to 8.96%, indicating that the risks of Cd mobility were reduced to low levels. The energy consumption and utilization efficiency of the method were 5.65 KWh m−3 and 11.25, respectively. The energy utilization efficiency was significantly higher than the efficiencies of other methods that use DC to improve Cd removal. The results suggested that the in situ removal of Cd by low-voltage DC and GAC was efficient and avoided the secondary release of Cd.

Charge transport behavior in XLPE-insulated cables under DC and thermal gradient coupling field considering the effects of non-uniform conductivity

The space charge accumulation of cross-linked polyethylene is the primary factor leading to the insulation failure of direct current (DC) cables, and the poor understanding of space charge transport behaviors remains as a bottleneck restricting the development of DC energy transmission technology. In this study, an improved bipolar charge transport model, considering the non-uniform conductivity of the insulation at DC voltage and thermal gradient is developed. The charge transport mechanism is revealed based on the space charge and the electric field distribution. The effects of conductivity on space charge and electric field distribution under DC voltage of polarity reversal is discussed as well. The results show that the space charge and the resulted electric field distribution are significantly affected by the temperature and the electric field gradient. A higher conductivity contributes to suppressing space charge accumulation, and a homogenization of electric field is achieved by an appropriate increase in the conductivity. Besides, the increase in the conductivity does not aggravate the space charge accumulation and distort the electric field after the polarity reversal.