基于弹性振动和深度学习的变压器状态识别

针对当前传统的变压器状态识别算法需要人工干预的问题,研究了一种能够自动提取特征并分类的一维卷积神经网络算法。该算法通过3层卷积池化层自动提取信号特征,并通过全连接层展为一维矢量,最终通过Softmax层进行分类。鉴于弹性振动信号抗干扰能力较强,选择弹性振动信号作为信号处理研究对象,运用基于一维卷积神经网络和弹性振动的方法对变压器状态进行识别,并通过采集500kV变压器的弹性振动信号获取的数据集进行验证,结果表明该算法的准确率优于BP、SVM和SAE算法,能对变压器的不同状态实现自动有效识别。

GIS设备现场典型故障及质量管控措施研究分析

气体绝缘金属封闭开关设备(GIS)的内部放电、气体泄漏、微水超标、温升超标、互感器误差超标、振动噪声等故障的治理一直是GIS设备质量提升中的技术难点。对GIS设备典型故障原因进行了分析,指出异物引发的放电、绝缘件缺陷、机械传动系统不正常、装配及安装工艺不良是引发故障的主要原因;提出GIS设备质量管控和提升的措施:从GIS设备结构设计、零部件采购、工厂装配、出厂试验、现场安装等生产全流程进行质量管控,可以有效提升GIS设备质量,减少设备故障的发生。

国内某抽水蓄能电站发电电动机通风系统改造

国内某抽水蓄能电站发电电动机定子绕组端部通风冷却效果不佳,温升偏高,长时间运行会引起线棒绝缘加速老化。笔者对定子绕组端部温升偏高的原因进行分析,提出通风系统改造方案,并采用经典网络法和CFD流体解析法对通风系统改造方案进行分析。试验结果表明,改造后定子绕组端部温升大幅下降,改造效果显著。该改造实践结果可为类似机组通风系统设计提供一些借鉴。

基于新形势的工厂安全生产管理分析

随着社会经济的高速发展,国内工厂建设数量不断增加,规模不断扩大。自“安全发展”这一要求正式提出后,落实工厂安全生产管理工作愈发重要。若想切实达成安全生产目标,工厂就必须创建一套科学合理、可行性高的安全生产责任机制,实现对生产流程的规范化管控,在结合法律法规的基础上,合理借助法律措施对生产作业的安全性进行管控,以达成安全生产的目标,并确保生产标准和效果之间的和谐统一,使工厂始终保持安全生产状态。

机械制造工艺及精密加工技术

现阶段市场上出现了多种类型的机械设备,这些机械的应用范围显著扩大,在很多领域都发挥了其功能优势。随着机械产品需求的增多,人们对机械制造及加工提出了全新的要求,各企业需从这些要求出发,创新机械制造及加工工艺。在信息技术支持下,机械制造工艺、精密加工技术取得了一定的发展成效,未来的工作中相关人员需继续研究这些工艺技术,保持技术创新性。基于此,本文重点分析了机械制造工艺及精密加工技术的发展及应用现状,以期为实际工作提供参考与借鉴。

不同栓塞程度对颅内动脉瘤介入治疗后囊内血流动力学影响的数值模拟研究

目的研究弹簧圈栓塞不同栓塞程度下颅内动脉瘤内血流动力学变化,为临床血管内治疗策略的制定提供理论依据。方法基于脑动脉瘤血管造影的三维血管成像,在不同栓塞状态下,重建动脉瘤的三维模型,采用Ansys CFX软件包分析血流速度、壁面切应力(WSS)、压力分布和流场情况。结果与治疗前相比,动脉瘤顶端部分栓塞后瘤体明显缩小,瘤顶低WSS区域减小,瘤体内涡流减少但流速无变化,同时造成瘤顶部平均WSS增大为2.13 Pa;而继续栓塞后,使动脉瘤整体壁面切应力显著下降,残留瘤颈远端流速明显降低;无论栓塞与否,动脉瘤流入道血管壁的壁面压力均无明显变化。结论颅内动脉瘤囊内血流动力学变化受弹簧圈栓塞程度及其在瘤体内分布的影响。

基于EG8030单相变三相纯正弦波电路设计

将单相220 V交流转变为三相对称380 V交流,转变后的三相交流一般都夹杂着较高的三次谐波,如果用这种三相电源长时间给三相交流电机供电,将会导致电机发热严重,从而影响电机的寿命。为了解决这个问题,利用EG8030芯片能产生自带死区控制的三相纯正弦波信号的特点,对芯片外围电路设置反馈保护电路,使它工作在三相同步开环调压模式。经安装和调试,其性能指标达到预期目标。

高落差多分支管路结构对多联式空调系统能力影响的快速仿真

大型高层建筑所采用的多联式空调系统中,室外机与室内机之间存在高落差、管路结构中存在众多分支,导致室内机能力的衰减。为了提高大型高层建筑中多联式空调系统室内机的能力,需要开发可以快速评估管路分支与落差对于室内机能力影响的仿真软件。本文建立了管路分布参数模型和基于流体网络理论的系统流量分配模型,以准确反映管路内制冷剂的流动特性;建立了室内机换热器分相模型和电子膨胀阀脉冲数快速计算模型,以快速反映室内机的运行状态;开发了分层迭代的求解算法,以提高软件计算的速度。同时采用已有数据进行模型验证,结果表明:各模型的误差均在±12%范围内;常见的多联机结构形式下仿真的计算时间均在1 min范围内。利用仿真软件的算例分析得到:室内机与室外机间的落差每增加20 m,室内机能力衰减2.7%~11.9%;管路中经过的分支个数每增加1个,室内机能力衰减0.4%~9.7%。

基于实际运行数据的不同气候区冬季空气源热泵结霜特征分析

空气源热泵运行中存在的突出问题是室外机结霜而导致的机组性能下降。在实际应用中,当地气候条件下空气源热泵结霜的难易程度决定了大多数除霜技术的适用性。空气源热泵结霜的难易程度除了受气候影响外,还受系统运行性能甚至用户使用习惯的影响,难以做出定量的判断。因此本文提出结霜度时数的概念,以专门表征气候条件对结霜的影响。通过在国内多地采集空气源热泵实际运行数据,使得结霜度时数的计算更接近实际情况,再对运行数据进行拟合分析得到了不同功率类型的热泵系统的蒸发温度与室外干球温度之间的特征温差,此温差可以用来修正传统设计上所假设的某个定值。最后,根据不同特征温差下的结霜度时数分析,结合不同功率类型的热泵系统在国内275个城市的结霜特征,对这些城市进行了结霜气候分区,为空气源热泵系统进行气候适应性的设计以及控制策略开发提供参考。

纳米Al_(2)O_(3)改性多胶粉云母主绝缘的研究

提高大电机主绝缘材料的热传导性能及电寿命,对发电机安全运行及能效密度提高具有重要意义。本文以VPR多胶绝缘系统为基础,研究了多胶Al_2O_3纳米粉体改性主绝缘特性。试验结果表明,在保持材料工艺性、固化后机械性能及常规电气性能不变的情况下,改性材料导热系数提高约1.1倍;瞬时工频击穿电压平均值下降18.8%;电老化寿命可提高5~6倍。

构筑配电自动化系统的三种基本模式

阐述了目前配电自动化系统方案的构筑中 ,户外设备RTU、变电站和主配调站内 SCADA之间可以通过 3种联系方式构造的 3种基本模式 ,并对比分析了这 3种基本模式在实施过程中的特点和设备配置基本情况。这 3种基本模式可为目前电力部门规划配电自动化方案提供参考。文中还介绍了设备应用情况。

特高压交流开关型可控避雷器的参数选择和样机研制

鉴于特高压交流输电系统深度降低操作过电压的迫切需求,及目前操作过电压常规限制措施——断路器加装合闸电阻和常规避雷器在经济性和运行可靠性方面存在的不足,提出一种自适应运行条件变化的操作过电压柔性限制方法。该方法的核心内容是将在变电站线路侧安装可控避雷器和在线路中部安装常规避雷器结合起来,深度降低操作过电压,取消断路器合闸电阻。可控避雷器技术是操作过电压柔性限制方法的核心,目前主要聚焦于特高压交流开关型可控避雷器技术研究。阐述了开关型可控避雷器技术的工作原理;给出特高压交流开关型可控避雷器的参数选择,包括额定电压、可控比、避雷器本体参数和控制单元（包括控制开关和控制器）参数等;研制出避雷器本体、控制单元和控制器;在此基础上,经过整体集成,研制出可控比为15%的特高压交流开关型可控避雷器样机。并对样机开展了电气性能试验研究,充分验证了开关型可控避雷器的可行性和可靠性。可控避雷器的研制成功为特高压交流输电系统操作过电压限制提供了一种新技术,可显著提高工程的经济性和可靠性。

特高压交流开关型可控避雷器稳态电压分布

特高压交流开关型可控避雷器在结构型式上与常规避雷器不同,可控避雷器中,避雷器受控元件与控制单元并联,稳态运行电压下,控制单元处于分闸状态,开关断口间电容和断口对地电容对避雷器受控元件、乃至避雷器本体的电压分布都会产生影响。控制单元和避雷器本体的相对位置和距离不同,影响程度不同。需要对开关型可控避雷器的稳态电压分布进行专门研究,包括理论计算和试验测试。给出开关型可控避雷器的结构;利用场-路结合法对可控避雷器的稳态电压分布进行计算;利用光纤-电流法对可控避雷器的电压分布进行试验测试;将计算结果和试验结果进行对比分析,并给出了可控避雷器稳态电压分布的影响因素。研究结果是确定特高压交流开关型可控避雷器的结构型式和样机研制的基础。

Urinary nuclear magnetic resonance spectroscopy of a Bangladeshi cohort with hepatitis-B hepatocellular carcinoma: A biomarker corroboration study

AIM: To establish if a distinct urinary metabolic profile could be identified in Bangladeshi hepatitis-B hepatocellular carcinoma (HCC) patients compared to cirrhosis patients and controls.METHODS: Urine samples from 42 Bangladeshi patients with HCC (39 patients with hepatitis-B HCC), 47 with cirrhosis on a background of hepatitis B, 46 with chronic hepatitis B, and seven ethnically-matched healthy controls were analyzed using nuclear magnetic resonance (NMR) spectroscopy. A full dietary and medication history was recorded for each subject. The urinary NMR data were analyzed using principal component analysis (PCA) and orthogonal partial least squared discriminant analysis (OPLS-DA) techniques. Differences in relative signal levels of the most discriminatory metabolites identified by PCA and OPLS-DA were compared between subject groups using an independent samples Kruskal-Wallis one-way analysis of variance (ANOVA) test with all pairwise multiple comparisons. Within the patient subgroups, the Mann-Whitney U test was used to compare metabolite levels depending on hepatitis B e-antigen (HBeAg) status and treatment with anti-viral therapy. A Benjamini-Hochberg adjustment was applied to acquire the level of significance for multiple testing, with a declared level of statistical significance of P < 0.05.RESULTS: There were significant differences in age (P < 0.001), weight (P < 0.001), and body mass index (P < 0.001) across the four clinical subgroups. Serum alanine aminotransferase (ALT) was significantly higher in the HCC group compared to controls (P < 0.001); serum α-fetoprotein was generally markedly elevated in HCC compared to controls; and serum creatinine levels were significantly reduced in the HCC group compared to the cirrhosis group (P = 0.004). A three-factor PCA scores plot showed clustering of the urinary NMR spectra from the four subgroups. Metabolites that contributed to the discrimination between the subgroups included acetate, creatine, creatinine, dimethyamine (DMA), formate, glycine, hippurate, and trimethylamine-N-oxide (TMAO). A comparison of relative metabolite levels confirmed that carnitine was significantly increased in HCC; and creatinine, hippurate, and TMAO were significantly reduced in HCC compared to the other subgroups. HBeAg negative patients showed a significant increase in creatinine (P = 0.001) compared to HBeAg positive patients in the chronic hepatitis B subgroup, whilst HBeAg negative patients showed a significant decrease in DMA (P = 0.004) in the cirrhosis subgroup compared to HBeAg positive patients. There were no differences in metabolite levels in HCC patients who did or did not receive antiviral treatment.CONCLUSION: Urinary NMR changes in Bangladeshi HCC were identified, corroborating previous findings from Egypt and West Africa. These findings could form the basis for the development of a cost-effective HCC dipstick screening test.

支架植入治疗椎-基底动脉系统非囊状动脉瘤

后循环非囊状动脉瘤只占颅内动脉瘤的一小部分，包括梭形（fusiform）、狭长形（dolichoectatic）、transitional以及巨大蛇形动脉瘤（giant serpentine）等。这些动脉瘤所引起的临床症状与囊状动脉瘤有明显的不同，复杂的临床症候群归纳起来主要由动脉瘤的占位效应、破裂或缺血等机制引起，其中最常见的症状为动脉瘤压迫相邻结构所致。现有的研究均证明椎一基底动脉系统非囊状动脉瘤的自然转归很差。

HBsAg, HBcAg, and combined HBsAg/HBcAg-based therapeutic vaccines in treating chronic hepatitis B virus infection

BACKGROUND: As the host immunity is diminished in patients with chronic hepatitis B (CHB), different approaches have been used to up-regulate their immune responses to produce therapeutic effects. But, cytokines, growth factors and polyclonal immune modulators could not exhibit sufficient therapeutic effects in these patients. Immune therapy with HBV-related antigens (vaccine therapy) has been used in CHB patients. But there is a paucity of information about the design of HBV antigen-based immune therapy in these patients. DATA SOURCE: Preclinical and clinical studies on immune therapy with HBsAg-based vaccine, HBcAg and combination of HBsAg/HBcAg-based vaccines have been discussed. RESULTS: HBsAg-based prophylactic vaccine was used as an immune therapeutic agent in CHB patients; however, monotherapy with HBsAg-based immune therapy could not lead to sustained control of HBV replication and/or liver damages. HBsAg-based vaccine was used as a combination therapy with cytokines, growth factors, and antiviral drugs. HBsAg-based vaccine was also used for cell-based therapy. However, satisfactory therapeutic effects of HBsAg-based vaccine could not be documented in CHB patients. In the mean time, evidences have supported that HBcAg-specific immunity is endowed with antiviral and liver protecting capacities in CHB patients. Recent data concentrate on the clinical use of combined HBsAg- and HBcAg-based vaccines in CHB patients.CONCLUSION: Antigen-based immune therapy with HBV- related antigens may be an alternative method for the treatment of CHB patients but proper designs of antigens, types of adjuvants, dose of vaccinations, and routes of administration need further analyses for the development of an effective regimen of immune therapy against HBV.

Investigation and Improvement of the Staggered Labyrinth Seal

Recent studies on staggered labyrinth seals have focused on the effects of different parameters,such as the pressure ratio and rotational speed on the leakage flow rate.However,few investigations pay sufficient attention to flow details and the sealing mechanism,which would be of practical importance in designing seals having higher performance.This paper establishes a theoretical model to study the seal mechanism,thus revealing that leakage is determined by the pressure ratio and geometric structure.Numerical simulation is implemented to illustrate details of the flow field within the seal structure.Viscous dissipation is used to quantitatively investigate the contribution that each location makes to the seal performance,revealing that orifices and stagnation points are the most important positions in the seal structure,generating the most dissipation.The orifice is carefully studied by using the theoretical model.Experiments for different pressure ratios are conducted and the results match well with those of the theoretical model and numerical simulation,verifying the theoretical model and analysis of the seal mechanism.Three new designs,based on a good understanding of the seal mechanism,are presented,with one reducing leakage by 24.5%.

Hemodynamics in the portal vein evaluated by pulse wave Doppler ultrasonography in patients with chronic hepatitis C treated with interferon

AIM: To employ pulse wave Doppler ultrasonography to evaluate the changes in portal blood flow velocity in patients with chronic hepatitis C (CHC) receiving interferon (IFN) treatment. METHODS: The subjects in this study were 14 patients (13 men and l woman) with CHC who received IFN treatment. Portal blood flow velocity was measured in the vessels at the porta hepatis at four time points: before IFN administration (pre-IFN), 2 wk after the start of administration (wk 2), 24 wk after the start of administration (wk 24, i.e., the end of IFN administration), and 24 wk after the end of administration (wk 48). RESULTS: The patients with CHC in whom IFN treatment resulted in complete elimination or effective elimination of viruses showed a significant increase in portal blood flow velocity at the end of IFN treatment compared with that before IFN treatment. In contrast, when IFN was ineffective, no significant increase in portal blood flow velocity was observed at wk 24 or 48 compared with the pre-IFN value. In addition, the patients with CHC in whom IFN was ineffective showed significantly lower portal blood flow velocity values than control subjects at all measurement time points. CONCLUSION: Pulse wave Doppler ultrasonography is a noninvasive and easily performed method for evaluating the effects of IFN treatment in patients with CHC. This technique is useful for measuring portal blood flow velocity before and 24 wk after IFN administration in order to evaluate the changes over time, thus assessing the effectiveness of IFN treatment.

Non-invasive determination of hepatic steatosis by acoustic structure quantification from ultrasound echo amplitude

AIM:To use leptin-deficient(ob/ob) mice with demonstrated differences in steatosis levels to test a new diagnostic method using the acoustical structure quantification(ASQ) mode and the associated analytical parameter,"focal disturbance ratio"(FD-ratio).METHODS:Nine ob/ob mice,at 5,8,and 12 wk of age(n = 3 in each age group),were used as models for hepatic steatosis.Echo signals obtained from ultrasonography in the mice were analyzed by ASQ,which uses a statistical analysis of echo amplitude to estimate inhomogeneity in the diagnostic region.FD-ratio,as calculated from this analysis,was the focus of the present study.FD-ratio and fat droplet areas and sizes were compared between age groups.RESULTS:No fibrosis or inflammation was observed in any of the groups.The fat droplet area significantly(P < 0.01) increased with age from 1.25% ± 0.28% at 5 wk to 31.07% ± 0.48% at 8 wk to 51.69% ± 3.19% at 12 wk.The median fat droplet size also significantly(P < 0.01) increased with age,from 1.33(0.55-10.52) m at 5 wk,2.82(0.61-44.13) m at 8 wk and 6.34(0.66-81.83) m at 12 wk.The mean FD-ratio was 0.42 ± 0.11 at 5 wk,0.11 ± 0.05 at 8 wk,and 0.03 ± 0.02 at 12 wk.The FD-ratio was significantly lower at 12 wk than at 5 wk and 8 wk(P < 0.01).A significant negative correlation was observed between the FD-ratio and either the fat droplet area(r =-0.7211,P = 0.0017) or fat droplet size(r =-0.9811,P = 0.0052).CONCLUSION:This tool for statistical analysis of signals from ultrasonography using the FD-ratio can be used to accurately quantify fat in vivo in an animal model of hepatic steatosis,and may serve as a quantitative biomarker of hepatic steatosis.

Recent Advances in ^(19)Fluorine Magnetic Resonance Imaging with Perfluorocarbon Emulsions

The research roots of 19fluorine （19F） magnetic resonance imaging （MRI） date back over 35 years. Over that time span, 1H imaging flourished and was adopted worldwide with an endless array of applications and imaging approaches, making magnetic resonance an indispensable pillar of biomedical diagnostic imaging. For many years during this timeframe, 19F imaging research continued at a slow pace as the various attributes of the technique were explored. However, over the last decade and particularly the last several years, the pace and clinical relevance of 19F imaging has exploded. In part, this is due to advances in MRI instrumentation, ~gF/1H coil designs, and ultrafast pulse sequence development for both preclinical and clinical scanners. These achievements, coupled with interest in the molecular imaging of anatomy and physiology, and combined with a cadre of innovative agents, have brought the concept of ~gF into early clinical evaluation. In this review, we attempt to provide a slice of this rich history of research and development, with a particular focus on liquid perfluorocarbon compound-based agents.