Study of accelerated aging of 15 kv XLPE and EPR cable insulation by switching impulses and elevated AC voltage

Accelerated aging of 15 kV Cross-linked Polyethylene (XLPE) and Ethylene Propylene Rubber (EPR) power cables was carried out in the experiments set for the study of this thesis. The degradation of cable insulation under different aging conditions was studied and compared. The study helped to understand the effects of different factors on the aging of XLPE and EPR cable insulation. In the study, degradation of XLPE cable insulation caused by switching impulses was investigated. The deterioration of EPR cable insulation initiated by elevated ac voltage and switching impulses were also studied. Measurements of partial discharge parameters, capacitance, and dissipation factor were analyzed to evaluate the condition of cable insulation during accelerated aging process. Measurement of ac breakdown voltage provided evidence of the cables’ remaining dielectric strength after accelerated aging

The Multi-Stress Aging of 15 kV EPR Power Cables

This research is focused on the multi-stress aging phenomena and lifetime estimation of 15 kV EPR cable. In order to gain the suitable parameters for the lifetime estimation, the aging study on the EPR cable samples as well as on the cable layers’ dielectrics samples was carried out at the High Voltage Laboratory of Mississippi State University. During the multi-stress aging study of 15 kV EPR cable samples, the EPR cable samples underwent electrical stress, thermal stress, and environmental effects. The aging time for the EPR cables varied from 650 hrs to 1300 hrs. An empirical aging model describing the cables’ lifetime was derived from the partial discharge measurements results. The aging study on the EPR cable layers’ dielectrics was achieved as well. The EPR insulation material samples were aged by combined electrical and thermal stress, while the material samples of inner semi-conducting layer, outer semi-conducting layer, and outer low-density polyethylene (LDPE) jacket were aged by thermal stress. The measurement data was used for the newly proposed lifetime estimation method. A new lifetime estimation method was introduced for the EPR cables. The method assumed that the failures of cables results from the expansion of voids/cavities initiated from the defects in the EPR insulation layer. The proposed lifetime estimation method applied the finite element method (FEM) to solve the electric field distribution inside the EPR cable with the existence of voids/cavities. The parameters were derived from the aging study on the EPR insulation material samples. Assuming the voids/cavities would expand in the direction of the maximum electric field stress, the lifetime of the EPR cables was then estimated through the iteration. The introduced method helped to establish a relationship between the aging study of insulation material samples and the aging of EPR cable samples, which was long missing in the past studies. It also provided a new way to assess the reliability of the EPR cable

DEVELOPMENT OF A KIND OF FLAVORING TABLETS FOR CHILDREN'S USE

Objective: In this study, based on children's medication preferences, Synsepalum dulcificum and Siraitia grosvenorii as raw material were used to develop a flavoring medicine for children. Methods:  Synsepalum dulcificum and Siraitia grosvenorii as the raw material were applied to extract the Synsepalum dulcificum powder and Siraitia grosvenorii powder respectively, according to the orthogonal test design; the optimal proportion of flavoring powder was obtained. Low-substituted hydroxypropyl cellulose(L-HPC), polyvinylpolypyrrolidone(PVPP), sodium carboxymethyl starch(CMS-Na）, microcrystalline cellulose(MCC) were taken, according to the orthogonal test design the optimum proportion of auxiliary materials, then the flavoring tablets was prepared according to the preparation process. Results: Through orthogonal test design, the optimum ratio of Synsepalum dulcificum: Siraitia grosvenorii was 1:3, and mixing them up in proportion; the optimum ratio of L-HPC: PVPP: CMS-Na: MCC was 10: 8: 3: 6, and mix them up in proportion. Equal amounts of sugar and salt were obtained by mass ratio of 1 to 1. Mixing 1/3 amount of flavoring powder with 3/4 amount of auxiliary materials, using 20% ethanol as a wetting agent, using the remaining sugar as a filler, and granulating. After the granules were dried and whole grain, add the remaining auxiliary materials and magnesium stearate were added, then the flavoring tablets were prepared. Conclusion: The effects of this formula were prominent, which could effectively intervene the taste of children's medicine; solve the practical problems concerning taking medications in children. Keywords: Synsepalum dulcificum; Siraitia grosvenorii; drug use in children; flavoring tabletsÂ

Efficacy and safety of Danggui Niantong Decoction in patients with gout: a systematic review and meta-analysis

Background: This study aims to evaluate the efficacy and safety of Danggui Niantong Decoction (DGNT) systematically on gout treating.Methods: This study was registered in PROSPERO, and the registration number was CRD42021271607. By the end of December, 2022, literature research was conducted among eight electronic databases. Main results of this study were blood uric acid (BUA) and Creactive protein (CRP). Secondary outcomes were erythrocyte sedimentation rate (ESR), serum creatinine (Scr), urinary protein quantified at 24 h (Upro), and interleukin-8 (IL-8). Study screening, data collection, as well as quality assessment were performed by two reviewers independently, and analysis was completed using Stata (SE15.0) and Review Manager (5.4).Results: A total number of 13 studies were included in our meta-analysis (n = 1,094 participants). Results showed DGNT combined with conventional western medicine (CWM) was more effective than WM alone in BUA (weighted mean differences (WMD) = −3.49, 95% confidence interval (CI) [−50.36, −32.59], p = 0.000), CRP (WMD = −41.48, 95% CI [−4.32, −2.66], p = 0.017), ESR (WMD = −6.23, 95% CI [−9.28, −3.17], p = 0.019), Scr (WMD = −18.64, 95% CI [−23.09, −14.19], p = 0.001), Upro (WMD = −0.72, 95% CI [−0.91, −0.53], p = 0.000), and IL-8 (WMD = −4.77, 95% CI [−11.48, 1.94], p = 0.000). None of the adverse effects noted were severe, and no life-threatening event was reported.Conclusion: This study shows that DGNT combined with CWM seems to have an effective clinical therapeutic potential. In addition, it also provides a scientific basis for better clinical application of DGNT in the future.Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021271607; Identifier: PROSPERO, CRD42021271607

A review on radiation-induced nucleation and growth of colloidal metallic nanoparticles

This review presents an introduction to the synthesis of metallic nanoparticles by radiation-induced method, especially gamma irradiation. This method offers some benefits over the conventional methods because it provides fully reduced and highly pure nanoparticles free from by-products or chemical reducing agents, and is capable of controlling the particle size and structure. The nucleation and growth mechanism of metallic nanoparticles are also discussed. The competition between nucleation and growth process in the formation of nanoparticles can determine the size of nanoparticles which is influenced by certain parameters such as the choice of solvents and stabilizer, the precursor to stabilizer ratio, pH during synthesis, and absorbed dose

The Effect of Draft Ratio of Side-By-Side Barges on Fluid Oscillation in Narrow Gap

In the present study, the effects of the draft ratio of the floating body on the fluid oscillation in the gap are investigated by using the viscous fluid model. Numerical simulations are implemented by coupling wave2Foam and OpenFOAM. The Volume of Fluid (VOF) model is used to capture the free surface waves. It is verified that the numerical results agree well with the experimental and other results. It is firstly found that, within the water depth range investigated in the present study, the depth of the wave tank has a significant effect on the numerical results. As the depth of the wave tank increases, the oscillation amplitude of the narrow-gap fluid largely decreases and the resonant frequency of the fluid oscillation in the narrow gap increases. The results also reveal that the draft ratio of floating bodies has a significant nonlinear influence on the resonant frequency and on the oscillation amplitude of the fluid in the narrow gap. With an increase in the draft of either the floating body on the wave side or the one on the back wave side, the resonant frequency decreases. The increase in the draft of the floating body on the wave side causes an increase in the reflection wave coefficient and leads to a drop in the fluid oscillation amplitude, and the increase in the draft of the floating body on the back wave side triggers a decrease in the reflection wave coefficient and results in an increase in the fluid oscillation amplitude. Meanwhile, the viscous dissipation induced by the fluid viscosity synchronously increases with the oscillation amplitude of the fluid in the increasing gap. Moreover, it is found that the draft ratio mainly affects the horizontal force of the floating body on the back wave side and that the highest calculated force increases with the draft ratio

3D Numerical Simulations of Green Water Impact on Forward-Speed Wigley Hull Using Open Source Codes

A series of CFD RANS simulations are presented for Wigley hulls of two freeboard heights progressing with forward speed in waves. Free surface effects are captured using the Volume of Fluid (VOF) method embedded in open source software OpenFOAM. Comparisons of heave, pitch motions and added resistance of the first Wigley model against the experiments of Kashiwagi (2013) confirm the numerical validity of the hydrodynamic modelling approach. Further simulations for the lower-freeboard Wigley model reveal that the highest green water impact on decks appears in way of λ / L = 1.3 and at the highest instantaneous pitch amplitude where the water propagates far downstream and across the deck. The simulations also demonstrate that the green water events are associated with air bubble entrapment

Hybrid Convolutional Neural Network for Localization of Epileptic Focus Based on iEEG

Epileptic focus localization by analysing intracranial electroencephalogram (iEEG) plays a critical role in successful surgical therapy of resection of the epileptogenic lesion. However, manual analysis and classification of the iEEG signal by clinicians are arduous and time-consuming and excessively depend on the experience. Due to individual differences of patients, the iEEG signal from different patients usually shows very diverse features even if the features belong to the same class. Accordingly, automatic detection of epileptic focus is required to improve the accuracy and to shorten the time for treatment. In this paper, we propose a novel feature fusion-based iEEG classification method, a deep learning model termed Time-Frequency Hybrid Network (TF-HybridNet), in which short-time Fourier transform (STFT) and 1d convolution layers are performed on the input iEEG in parallel to extract features of the time-frequency domain and feature maps. And then, the time-frequency features and feature maps are fused and fed to a 2d convolutional neural network (CNN). We used the Bern-Barcelona iEEG dataset for evaluating the performance of TF-HybridNet, and the experimental results show that our approach is able to differentiate the focal from nonfocal iEEG signal with an average classification accuracy of 94.3% and demonstrates an improved accuracy rate compared to the model using only STFT or one-dimensional convolutional layers as feature extraction