Influence of Omega 3 Fatty Acid Supplementation on Phase Angle Values of People Living with HIV/AIDS with Lipodystrophy Secondary to Antiretroviral Therapy: A Randomized Clinical Trial

Objective: The measurement of phase angles is an important monitoring parameter and supplementation with omega-3 could promote benefits by modulating the electrical potential of membranes and increasing body cell mass. This study aimed to evaluate the effectiveness of omega-3 fatty acid supplementation on the phase angle of people living with HIV/AIDS. Methods: In this study, 63 individuals of all genders who were undergoing outpatient follow-up and showed lipodystrophy due to highly active antiretroviral therapy were analyzed. Our sample consisted of two groups, one that received supplementation containing 2550 mg of omega-3/day (1080 mg of eicosapentaenoic acid and 720 mg of docosahexaenoic acid) for three months (n = 32) and another that underwent nutrition guidance (n = 31). Phase angle and body cell mass were assessed for both groups and compared at the beginning of research (T0) and after our intervention (T1) for each group separately. Results: Phase angle averaged 6.45° ± 1.06 SD. The comparison between T0 and T1 showed a significant increase in phase angle and body cell mass, whereas the guidance group showed a decrease in body cell mass at T1 in relation to T0, with a significant p-value. Variance in phase angle between moments showed significant values between T0 and T1 in the supplementation group for all genders. Conclusion: Omega-3 positively modulated patients phase angle and body cell mass, but we emphasize the need for other studies that can solidify knowledge about supplementation dosage and intervention time.

Role of the phase angle in the prognosis of the cirrhotic patient:15 years of follow-up

BACKGROUND In 2019,cirrhosis accounted for 2.4%of global deaths.The projection for 2030 is an increase in this index.In recent years,hospitalization costs have escalated by 36%for compensated cirrhosis and 24%for decompensated cirrhosis.Therefore,it is necessary to identify a tool capable of predicting the mortality of these patients according to their clinical condition and consequently extending their survival time.Different studies have shown that the phase angle(PA)can be a feasible method in clinical practice,with the potential to guide assertive patient management in the therapeutic of chronic liver disease.AIM To evaluate the prognostic role of PA in cirrhotic patients over a 15-year followup period.METHODS Retrospective cohort study with 129 cirrhotic patients of both sexes over 18 years old.Diagnosis of cirrhosis by liver biopsy.The first year of data collection was 2007,and data regarding outcomes was collected in 2023.Data were gathered from medical records,such as esophageal varices(EV),EV bleeding,ascites,spontaneous bacterial peritonitis(SBP),encephalopathy,laboratory findings and PA.The cut-off value for the PA was 5.4°,a value described in 2012 by Fernandes et al for 129 patients evaluated in this study and the cut-off points for the Brazilian population presented in percentiles(P),as described by Mattiello et al.The mortality was assessed using the PA percentile through Kaplan-Meier curves and multivariate binary logistic regression models.RESULTS Patients were divided into two groups according to the PA 5.4th(PA>5.4°,n=40;PA≤5.4°,n=89)PA percentile(<P50,n=56;≥P50 n=73).The percentile classification was more accurate in identifying long-term deaths than the 5.4ºPA.Patients with<P50 had a higher number of relevant complications such as ascites,SBP,liver encephalopathy and HCC.PA is strongly correlated with serum albumin(P<0.001),International Normalized Ratio(P=0.01),total bilirubin(P=0.02)and direct bilirubin(P=0.003).PA is correlated with survival time(P<0.001)and length of stay(P=0.02).Logistic regression analysis shows that an increase of 1°in PA enlarges the cirrhotic patient's chance of survival by 17.7%.CONCLUSION PA is a good predictor of morbidity and mortality for cirrhotic patients.The PA by percentile showed greater sensitivity in predicting mortality compared to the cut-off point of 5.4º.

Low phase angle is associated with the development of hepatic encephalopathy in patients with cirrhosis

AIM Evaluate the association between phase angle and the development of hepatic encephalopathy in the longterm follow-up of cirrhotic patients.METHODS This was a prospective cohort study. Clinical, nutritional and biochemical evaluations were performed. MannWhitney's U and χ2 tests were used as appropriate. Kaplan-Meier curves and Cox proportional Hazards analysis were used to evaluate the prediction and incidence of hepatic encephalopathy.RESULTS Two hundred and twenty were included; the most frequent etiology of cirrhosis was hepatitis C infection, 52% of the patients developed hepatic encephalopathy(18.6% covert and 33.3% overt); the main precipitating factors were infections and variceal bleeding. KaplanMeier curves showed a higher proportion of HE in the group with low phase angle(39%) compared to the normal phase angle group(13%)(P = 0.012). Furthermore, creatinine and phase angle remained independently associated to hepatic encephalopathy in the Cox regression multivariate analysis [hazard ratio = 1.80(1.07-3.03)]. CONCLUSION In our cohort of patients low phase angle was associated with an increased incidence of hepatic encephalopathy. Phase angle is a useful nutritional marker that evaluates cachexia and could be used as a part of the integral assessment in patients with cirrhosis.

Nutritional evaluation in cirrhosis: Emphasis on the phase angle

Protein-calorie malnutrition (PCM) is a common condition in cirrhotic patients, leading to a worse prognosis, complications, poor quality of life and lower survival rates. Among ways of assessing nutritional status, there are anthropometric methods such as the evaluation of the triceps skinfold, the arm circumference, the arm muscle circumference and the body mass index, and non-anthropometric methods such as the subjective global assessment, the handgrip strength of non-dominant hand, and the bioelectrical impedance analysis (BIA). PCM is frequently under-diagnosed in clinical settings in patients with cirrhosis due to the limitations of nutritional evaluation methods in this population. BIA is a useful method, but cannot be indicated in patients with abnormal body composition. In these situations, the phase angle (PA) has been used, and can become an important tool in assessing nutritional status in any situation. The PA is superior to anthropometric methods and might be considered as a nutritional indicator in cirrhosis. The early characterization of the nutritional status in patients with cirrhosis means an early nutritional intervention, with a positive impact on patients&rsquo; overall prognosis. Among the usually accepted methods for nutritional diagnosis, the PA provides information in a quick and objective manner.

Phase angle obtained by bioelectrical impedance analysis independently predicts mortality in patients with cirrhosis

AIM To evaluate the prognostic value of the phase angle(PA)obtained from bioelectrical impedance analysis(BIA) for mortality prediction in patients with cirrhosis. METHODS In total, 134 male cirrhotic patients prospectively completed clinical evaluations and nutritional assessment by BIA to obtain PAs during a 36-mo follow-up period. Mortality risk was analyzed by applying the PA cutoff point recently proposed as a malnutrition marker(PA ≤ 4.9°) in Kaplan-Meier curves and multivariate Cox regression models. RESULTS The patients were divided into two groups according to the PA cutoff value(PA > 4.9°, n = 73; PA ≤ 4.9°, n = 61). Weight, height, and body mass index were similar in both groups, but patients with PAs > 4.9° were younger and had higher mid-arm muscle circumference, albumin, and handgrip-strength values and lower severe ascites and encephalopathy incidences, interleukin(IL)-6/IL-10 ratios and C-reactive protein levels than did patients with PAs ≤ 4.9°(P ≤ 0.05). Forty-eight(35.80%) patients died due to cirrhosis, with a median of 18 mo(interquartile range, 3.3-25.6 mo) follow-up until death. Thirty-one(64.60%) of these patients were from the PA ≤ 4.9° group. PA ≤ 4.9° significantly and independently affected the mortality model adjusted for Model for End-Stage Liver Disease score and age(hazard ratio = 2.05, 95%CI: 1.11-3.77, P = 0.021). In addition, Kaplan-Meier curves showed that patients with PAs ≤ 4.9° were significantly more likely to die. CONCLUSION In male patients with cirrhosis, the PA ≤ 4.9° cutoff was associated independently with mortality and identified patients with worse metabolic, nutritional, and disease progression profiles. The PA may be a useful and reliable bedside tool to evaluate prognosis in cirrhosis.

Variations in electrical impedance and phase angle among seedlings of Pinus densata and parental species in Pinus tabuliformis habitat environment

Electrical impedance （El） and phase angle （PHI） parameters in AC impedance spectroscopy are important electrical parameters in the study of medical pathology. However, little is known about their application in variation and genetic relationship studies of forest trees. In order to test whether impedance parameters could be used in genetic relationship analysis among conifer species, E1 and PHI were measured in a seedling experiment test composed of Pinus tabuliformis, Pinus yunnanensis, and Pinus densata in a habitat of Pinus tabuliformis. The results showed that variations in both EI and PHI among species were sig- nificant in different electric frequencies, and the EI and PHI values measured in the two populations of P. densata were between the two parental species, P. yunnanensis and P. tabuliformis. These results show that these two impedance parameters could reflect the genetic relationship among pine species. This was the first time using the two AC impedance spectroscopy parameters to test the genetic relationship analysis between tree species, and would be a hopeful novelreference methodology for future studies in evolution and genetic variation of tree species.

Bioelectrical Impedance Phase Angle as a Predictors of Mortality in Patients with Lung Cancer:a Prospective Study

Objective Bioelectrical impedance analysis(BIA)is used to measure a patient's body composition.The phase angle(PA),the major parameter in BIA,is one of the most sensitive indicators of malnutrition.The aim of the current study was to investigate whether the PA can be used to predict survival in lung cancer patients.Methods One hundred sixty-six lung cancer patients were prospectively included from January 2014 to August 2016 in Daping Hospital.Anthropometric measurements,hematological values,the nutritional risk screening(NRS 2002)score,patient generated-subjective global assessment(PG-SGA)score,Karnofsky performance status(KPS)scale,European Organization for Research and Treatment of Cancer Core Quality of Life Questionnaire(EORTC QLQ C-30)score,and BIA were investigated within 48 hours after admission to the hospital.A Spearman correlation analysis was applied to test the correlations between the study characteristics and PA.A Kaplan-Meier analysis and log-rank test were conducted to analyze the association between the overall survival(OS)and PA.Results The mean age for all patients was 63 years old(42 females and 124 males).The median PA was 5.5°(4.70°,6.23°).The PA was positively associated with the body mass index,hand grip strength,mid-arm circumference,mid-arm muscle circumference,albumin,prealbumin,C-reactive protein,red blood cells,hemoglobin and KPS score.The PG-SGA scores,QLQ-C30 score,and NRS2002 score showed a significant negative association with the PA.According to a multivariate analysis,the PA(HR=0.47;95%CI:0.27-0.81)was independent predictor of the lung cancer patients'long-term OS.Patients with a higher PA(≥5°)had better overall survival(median=426 days)compared to those with a lower PA(<5°)(median=96 days)based on the one-year follow-up data(P<0.0001).Conclusions These studies indicate that the PA is a sensitive and early indicator to predict survival in lung cancer patients.

Low Phase Angle Predicts Poor Survival in Patients with Hepatocellular Carcinoma:A Retrospective Study

Background The phase angle(PA)is an indicator of nutritional status derived from bioelectrical impedance analysis(BIA).Studies have shown that the PA is one of several factors related to the survival of cancer patients.However,the correlation between the PA and prognosis in patients with hepatocellular carcinoma(HCC)has not been reported.This study aimed to explore the relationship between the PA,nutrition-related indicators,and patient prognosis.Methods The data from 248 HCC patients who underwent BIA between January 2015 and December 2019 at the First Hospital of Jilin University were retrospectively analyzed.Patients were divided into two groups according to the median PA value,then the nutrition-related indicators and overall survival(OS)were compared between the two groups.The correlations between the PA and laboratory test nutrition-related indicators and the results of a body composition analysis were determined using Pearson correlation analysis.Independent predictors of the patient prognosis were identified using univariate and multivariate analyses.Results The median OS in the high and low PA groups were 70 and 54.6 months,respectively(P=0.004).The Pearson correlation analysis revealed that the PA was associated with both laboratory test nutrition-related indicators and the results of a body composition analysis.The multivariable Cox regression analysis identified the PA as an independent risk factor affecting the prognosis of patients with Barcelona Clinic Liver Cancer stage A or B.Conclusion The PA is a good biomarker for the nutritional status.We found that the PA was associated with the prognosis in patients with HCC,with a low PA indicating a poor nutritional status and worse prognosis.

Solid-state NMR studies of proteins in condensed phases

Some proteins perform their biological functions by changing their material states through liquid-liquid phase separation.Upon phase separation,the protein condenses into a concentrated liquid phase and sometimes into a gel phase,changing its dynamic properties and intermolecular interactions,thereby regulating cellular functions.Although the biological significance of this phenomenon has been widely recognized by researchers,there is still a lack of a comprehensive understanding of the structural and dynamic properties of the protein in the condensed phase.In this phase,molecules usually contain domains with varied dynamic properties and undergo intermediate exchanges.Magic angle spinning(MAS)solid-state NMR(SSNMR)experiments are very powerful in studying rigid protein polymers such as amyloid.The incorporation of solution-like experiments into SSNMR and the development of J-coupling based MAS SSNMR techniques extend its ability to study partially mobile segments of proteins in a condensed liquid or gel phase which are not visible by solution NMR or dipolar-coupling based SSNMR.Therefore,it has been applied in studying protein condensation and has provided very important information that is hard to obtain by other techniques.

Phase Properties of Two-Mode Squeezing-Rotating Entangled Representation

By virtue of the squeezing-rotating entangled representation, we mainly establish the new two-mode phase operator and phase angle operat, or, which is a general form including the foregoing formalist in two-mode Fock space. In addition, the corresponding phase distribution function is given in the entangled representation. In terms of this definition, we also analyze the phase behavior of some simple two-mode states such as squeezing-rotatlng coherent state, squeezing-rotating vacuum state, and so on. It is found that the results exactly agree with the foregoing phase theory.

Relationship between phase angle,steatosis,and liver fibrosis in patients coinfected with human immunodeficiency virus/hepatitis C virus

BACKGROUND Malnutrition,lipodystrophy,and dyslipidemia are prevalent characteristics in patients with human immunodeficiency virus(HIV)infection with or without previous treatment.Such a clinical condition can lead to the hypothesis of the presence of hepatic steatosis with possible progression to fibrosis and the risk of hepatocellular carcinoma.Notably,a low phase angle(PA),evaluated by bioelectrical impedance analysis(BIA),is an independent prognostic marker of clinical progression and survival in HIV-infected patients.AIM To evaluate the relationship between PA and body composition with steatosis and hepatic fibrosis in HIV/hepatitis C virus(HCV)-coinfected patients.METHODS A retrospective observational study by convenience sampling of coinfected HIV/HCV patients,in which all patients underwent transient elastography(Fibroscan)and BIA evaluation.Student’s t test was used for group comparisons,and Spearman’s or Pearson’s correlation test was used when appropriate.The significance level was set at 5%,and analyses were performed using SPSS version 21.0.RESULTS Forty-three patients who received antiretroviral therapy met the inclusion criteria,and 23(53.5%)were under treatment with protease inhibitors(PIs).There was no difference in PA between those who used PIs and those who did not(P=0.635).There was no correlation between fibrosis grade and PA(P=0.355)or lean mass(P=0.378).There was a significant inverse correlation between the controlled attenuation parameter(CAP)and lean mass(P=0.378),positive correlation between PA and lean mass(P=0.378),and negative correlation between PA and fatty mass(P=0.378),although the CAP and PA were not correlated.When evaluated by sex,no significant correlations were found.CONCLUSION PA determines the muscle function of HIV/HCV-coinfected patients,and the CAP values reinforce the association with lean mass,suggesting that patients require early nutritional interventions.

Phase angle and non-alcoholic fatty liver disease before and after bariatric surgery

BACKGROUND Obesity is a global health problem that is continuing to increase in the young population.In Brazil,the frequency of obesity in 2018 was 19.8%.Several comorbidities are directly associated with obesity,such as non-alcoholic fatty liver disease(NAFLD),which is considered the most common liver disorder in Western countries and affects up to 46%of adults.Bariatric surgery is effective in treating obesity and can improve NAFLD;however,the effect of bariatric surgery on body composition,phase angle(PA),and improving NAFLD needs to be further studied.AIM To analyze the PA in the postoperative period of bariatric surgery and to correlate it with changes in body composition and liver disease.METHODS This study is a retrospective cohort study of the analysis of the medical records of patients undergoing bariatric surgery in a reference center of a teaching hospital in Porto Alegre over a 2-year period.Patients older than 18 years whose record contained all information relevant to the study were included.The data analyzed were body composition and PA through electrical bioimpedance and NAFLD through liver biopsy in the pre-and postoperative period.The level of significance adopted for the statistical analyses was 5%.RESULTS We evaluated 379 patients with preoperative data.Regarding PA,169 patients were analyzed,and 33 patients had liver biopsy pre-and postoperatively with NAFLD information.In total,79.4%were female,with a mean age of 39.1±10.6 years.The average body mass index(BMI)was 45.9±7.5 kg/m².The PA showed a mean of 5.8±0.62°in the preoperative period and a significant reduction in the postoperative period.A postoperative reduction in body composition data(skeletal muscle mass,fat percentage,fat mass,body cell mass,BMI and visceral fat area)was shown as well.Regarding liver disease,all patients presented a reduction in the degrees and stages of liver disease in the postoperative period,and some had no degree of liver disease at all.CONCLUSION PA decreased after bariatric surgery,with a direct correlation with weight loss and changes in body composition.The decrease in PA was not correlated with the improvement in NAFLD.

Phase angle through electrical bioimpedance as a predictor of cellularity in inflammatory bowel disease

It is estimated in Western industrialized countries that inflammatory bowel disease(IBD)has a prevalence of 1 for every 200 inhabitants.In the past,the fat mass disproportionate increase in relation to the fat-free mass was considered uncommon in patients with IBD,due to the observation of the disease being more common with weight loss and malnutrition.However,more in-depth investigations demonstrate that the fat/lean mass disproportion stands out both in prevalence in patients with new diagnoses of ulcerative colitis or Crohn's disease as well as a factor of poor prognosis to the natural evolution of the disease or to the therapeutic response.Another important aspect associated with obesity in IBD is the increased risk of drug clearance[including anti-tumor necrosis factor(TNF)and anti-integrin agents],resulting in short half-life and low trough drug concentrations,since the levels of TNF secreted by adipocytes sequester anti-TNF agents,which could result in suboptimal response to biologics.In view of these characteristic aspects of the inflammatory process of IBD,the identification of cellular functioning is necessary,which can be associated with the staging of the underlying disease,biochemical parameters,and body composition,helping as an indicator for a more accurate clinical and nutritional conduct.

Application of the Phase Angle in Patients with Malignant Tumors

Bioelectrical impedance analysis(BIA)is a noninvasive and reproducible technique for assessing changes in body composition and nutritional status.The phase angle(PA),a major parameter of BIA,is one of the most sensitive indicators used to detect malnutrition in patients,and is also a prognostic marker in various clinical diseases.The incidence of malnutrition in cancer patients is high,and malnutrition seriously affects the treatment process and prognosis of patients.Reasonable and effective nutritional interventions are therefore of great significance for cancer patients.Compared with traditional nutritional assessment tools,the PA has unique advantages in the nutritional assessment,efficacy monitoring and prognostic prediction of patients with malignant tumors,and it has broad application prospects in clinical practice.This article reviews the research progress on the application of the PA in patients with malignant tumors to provide clinicians with a tool to predict malnutrition,and provide a more favorable basis for the nutritional assessment,treatment and prognostic prediction of cancer patients.

Design of Overall Slope Angle and Analysis of Rock Slope Stability of Chadormalu Mine Using Empirical and Numerical Methods

In engineering projects associated with rock mechanic science like open pit mines, assessment and slope stability of mine walls is one of the important performance in generate of these structures. Estimating and knowledge of stable slope angle is one of main parts that should be occurring to special attention in open pit mines studies phase. Considering the importance of economic costs in mining issues, the need for appropriate design slope angle that can cause an adverse minimize project costs and throws the other hand, the stability conditions in the safe walls of the mine life will provide essential and seems obvious. Therefore, in this study to determine the optimal slope angle of overall and bench of west wall of the Chadormalu ore iron mine, has been trying, first, done field studies on the discontinuity of western wall, engineering classification and geomechanical properties of rock masses of wall, then assess the amount of optimal slope angle using empirical method. Finally, in order to ensure stability and accuracy of the wall slope angle based on the obtained (empirical method) tries to analysis is amount of Factor of Safety (FOS), displacements and mean stress condition atwalls calculated from drilling use Phase2D powerful software.

Fault Line Selection Method Considering Grounding Fault Angle for Distribution Network

In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line selection always existed in existing methods. According to the characteristics that transient current was different between the fault feeder and other faultless feeders, wavelet transformation was performed on data of the transient current within a power frequency cycle after the fault occurred. Based on different fault angles, wavelet energy in corresponding frequency band was chosen to compare. The result was that wavelet energy in fault feeder was the largest of all, and it was larger than sum of those in other faultless feeders, when the bus broke down, the disparity between each wavelet energy was not significant. Fault line could be selected out by the criterion above. The results of MATLAB/simulink simulation experiment indicated that this method had anti-interference capacity and was feasible.

慢性病共病、相位角与老年人肌少症相关的肌肉质量减少的关系研究

目的·探讨慢性非传染性疾病(慢性病)共病、相位角与老年人肌少症相关的肌肉质量减少的相关性,以及慢性病共病、相位角对老年人肌肉质量减少的预测价值。方法·对2018年8月1日—2019年7月31日入住上海交通大学医学院附属仁济医院老年科,年龄≥60岁的患者进行回顾性筛查。收集患者基本情况(性别、年龄、用药数、共病数、有无骨质疏松症、有无吸烟史等),以及实验室检查指标(血红蛋白、白蛋白、血肌酐、血尿酸、铁蛋白、维生素D、三酰甘油、总胆固醇、高密度脂蛋白、低密度脂蛋白等)结果。计算年龄调整后查尔森合并症指数(age-adjusted Charlson comorbidity index,aCCI)。采用InBody S10生物电阻抗身体成分检测仪进行人体成分测试,记录身体质量指数(body mass index,BMI)、骨骼肌质量指数(skeletal muscle mass index,SMI)、相位角(phase angle,PhA)。部分患者接受握力测量。肌肉质量减少采用2019年亚洲肌肉减少症工作组(Asian Working Group for Sarcopenia,AWGS)推荐的SMI值(男性≤7.0 kg/m^(2)、女性≤5.7 kg/m^(2))进行诊断。根据测定的SMI值将患者分为肌肉质量正常组与肌肉质量减少组。采用单因素和多因素Logistic分析老年患者发生肌少症相关的肌肉质量减少的危险因素。并进一步运用受试者操作特征曲线(receiver operator characteristic curve,ROC曲线)及曲线下面积评估相关因素预测肌肉质量减少的价值。结果·共入组慢性病共病患者359例,其中男性226例,女性133例;肌肉质量正常组241例,肌肉质量减少组118例,老年人肌少症相关的肌肉质量减少发生率为32.9%。单因素Logistic回归分析提示年龄(OR=1.036,95%CI 1.013~1.060)、共病数(OR=1.117,95%CI1.025~1.217)、aCCI(OR=1.123,95%CI 1.031~1.222)、高密度脂蛋白(OR=3.688,95%CI 2.065~6.622)与老年人肌肉质量减少的风险呈正相关,BMI(OR=0.514,95%CI 0.443~0.597)、PhA(OR=0.195,95%CI 0.126~0.303)、血红蛋白(OR=0.984,95%CI 0.972~0.996)、三酰甘油(OR=0.606,95%CI 0.424~0.866)与老年人肌肉质量减少的风险呈负相关。多因素Logistic回归模型提示PhA(OR=0.338,95%CI 0.119~0.959)、BMI(OR=0.634,95%CI 0.476~0.844)与老年人肌肉质量减少的风险呈负相关。BMI、PhA预测老年人肌少症相关的肌肉质量减少的ROC曲线下面积分别为0.893(95%CI 0.855~0.931)和0.786(95%CI 0.736~0.837),敏感度分别为0.724和0.676,特异度分别为0.916和0.762;BMI联合PhA预测老年人肌肉质量减少的ROC曲线下面积为0.917(95%CI 0.883~0.951),敏感度为0.867,特异度为0.860。结论·aCCI与老年人肌少症相关的肌肉质量减少具有相关性。随着BMI、PhA的下降,老年人肌肉质量减少的风险升高。BMI联合PhA具有较高的老年人肌少症相关的肌肉质量减少的预测价值。未发现慢性病共病对其的预测价值。

对称故障下变流器控制对差动保护影响及优化策略

变流器输出故障特征的强可控性给交流系统继电保护带来了严峻挑战。该文分析并网线路发生对称故障时跟网型变流器的控制响应过程,从故障期间变流器电流控制目标不能自动匹配故障回路功率需求的角度,分析推导变流器网侧电压相位发生跳变并不断旋转的变化特征。受故障回路阻抗约束,变流器输出短路电流相位与网侧电压相位同步变化,造成并网线路差动保护性能严重下降。基于变流器网侧电压相位变化机理,从电流控制目标与锁相环控制两个维度,提出兼顾保护需求和供电需求的变流器控制优化策略。仿真结果表明,并网线路对称故障时所提策略能有效抑制两侧电流相位差,显著提升了差动保护动作性能。

宽角度位相调控反射镜的设计与研制

宽角度位相调控反射镜是下一代中高轨量子通信系统中的核心元件,用于宽角度范围内信号光的高效传递与偏振态的精确调控。基于等效多层膜理论,采用介质反射膜堆加非规整位相调控膜的膜系结构,设计了一种宽角度位相调控反射镜。选择Nb2O5和SiO2分别作为高、低折射率薄膜材料,通过误差分析,优化沉积工艺,采用电子束蒸发结合离子辅助沉积的方式,在德国莱宝Lab900-plus设备上制备出该薄膜元件。研制结果表明,反射镜在780 nm处、45°±7.5°入射范围内,其反射率大于99.3%,位相差控制在3°以内,满足量子通信系统的反射率及位相差控制要求,且通过相关环境模拟实验,满足可靠性要求,为该类偏振调控薄膜元件在下一代中高轨量子卫星中的工程应用打下了坚实的基础。