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Study on Various Rectifiers for Fan-Filter Units 被引量:3
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作者 刘俊杰 涂光备 马九贤 《Transactions of Tianjin University》 EI CAS 2002年第2期119-124,共6页
The face velocities of the high efficiency particulate air filters and the ultra low penetration airfilters in fan filter units (FFUs) have large relative standard deviation and turbulivity. It seriously affects the ... The face velocities of the high efficiency particulate air filters and the ultra low penetration airfilters in fan filter units (FFUs) have large relative standard deviation and turbulivity. It seriously affects the unidirectivity of the flow in the unidirectional flow clean zone and cleanroom. The cross contamination in this kind of unidirectional flow area is hardly controlled. It is significant to find optional method for keeping the face velocity uniformity of FFU and reducing the face velocity turbulivity of FFU, furthermore, to keep the cleanliness level under FFUs. The normal and easy method is to add flow rectifiers under filters. FFUs with various flow rectifiers have been tested. The uniformity and turbulivity of facevelocity under the FFU are presented in this paper. The influence of the facevelocity uniformity and turbulivity on the contamination boundary of the unidirectional flow is studiedas well. 展开更多
关键词 unidirectional flow air velocity UNIFORMITY turbulivity flow rectifier fan filter unit (FFU)
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Generic functional modelling of multi-pulse auto-transformer rectifier units for more-electric aircraft applications 被引量:1
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作者 Tao YANG Serhiy BOZHKO +2 位作者 Patrick WHEELER Shaoping WANG Shuai WU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2018年第5期883-891,共9页
The Auto-Transformer Rectifier Unit(ATRU) is one preferred solution for high-power AC/DC power conversion in aircraft. This is mainly due to its simple structure, high reliability and reduced k VA ratings. Indeed, t... The Auto-Transformer Rectifier Unit(ATRU) is one preferred solution for high-power AC/DC power conversion in aircraft. This is mainly due to its simple structure, high reliability and reduced k VA ratings. Indeed, the ATRU has become a preferred AC/DC solution to supply power to the electric environment control system on-board future aircraft. In this paper, a general modelling method for ATRUs is introduced. The developed model is based on the fact that the DC voltage and current are strongly related to the voltage and current vectors at the AC terminals of ATRUs. In this paper, we carry on our research in modelling symmetric 18-pulse ATRUs and develop a generic modelling technique. The developed generic model can study not only symmetric but also asymmetric ATRUs. An 18-pulse asymmetric ATRU is used to demonstrate the accuracy and efficiency of the developed model by comparing with corresponding detailed switching SABER models provided by our industrial partner. The functional models also allow accelerated and accurate simulations and thus enable whole-scale more-electric aircraft electrical power system studies in the future. 展开更多
关键词 Asymmetric transformer Functional modelling More-Electric Aircraft Multi-pulse rectifier Transformer rectifier unit
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Control of Unit Power Factor PWM Rectifier
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作者 Meifang Xue Mingzhi He 《Energy and Power Engineering》 2013年第4期121-124,共4页
To solve the problem of harmonic pollution to the power grid that caused by traditional diode rectifier and phase controlled rectifier, the unit power factor PWM rectifier is designed. The topology structure of the re... To solve the problem of harmonic pollution to the power grid that caused by traditional diode rectifier and phase controlled rectifier, the unit power factor PWM rectifier is designed. The topology structure of the rectifier circuit is introduced and the double closed-loop control strategy in three-phase stationary coordinate system is analyzed. For the deficiency of control strategy, the control strategy in two-phase synchronous rotating coordinate system is proposed. This makes the independent control of active current and reactive current to be realized. The simulation model of the PWM rectifier is built and the effectiveness of the control method proposed in this paper is verified by simulation. 展开更多
关键词 CONTROL PWM rectifier unit Power FACTOR d q COORDINATES
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Regeneration Potential of Woody Species at the Side of Secondary Roads Post-Logging of Loundoungou-Toukoulaka Forest Management Unit, Republic of the Congo
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作者 Chauvelin Douh Larisa Mbouchi Malonga +4 位作者 Donatien N’zala Belvina Chardène Mabengo Christian Moussoumbou Saint Fédriche Ndzaï Félix Koubouana 《Natural Resources》 2023年第7期102-120,共19页
Natural regeneration is the basis of a dynamic and demographic balance of plant populations. The objective of this study was to assess the natural regeneration potential of woody species along secondary roads post-log... Natural regeneration is the basis of a dynamic and demographic balance of plant populations. The objective of this study was to assess the natural regeneration potential of woody species along secondary roads post-logging abandoned since 2008 and 2018. In the two Annual Allowable Cuts (AAC 2008 and AAC 2018), 24 regenerating sub-plots (i.e. 12 sub-plots for AAC 2008 and 12 sub-plots for AAC 2018) with a unit area of 5 m × 5 m were delimited with a total area of 0.06 ha (i.e. 0.03 ha for each AAC). The abundance and diversity of woody species were respectively inventoried and estimated. Two estimators of the specific richness were used to estimate the floristic diversity of each Annual Allowable Cuts (AAC). The results reveal globally 88 woody species in the AAC 2008 and 241 woody species in the AAC 2018, with respective average densities of 2933 stem/ha and 8033 stem/ha. There was a very highly significant difference between the mean densities of the two AAC (Kruskal-Wallis test;H = 2.36, p-value < 0.000). The results also highlight a great diversity and a relatively high abundance of woody species in the 2018 AAC compared to the 2008 AAC. Also, the spatial structuring of the sub-plots on the basis of Principal Component Analysis (PCA) demonstrates that the floristic composition of the two AAC is globally different. The study suggests silvicultural interventions and the long-term assessment of regenerating woody species along abandoned secondary roads in order to guarantee the sustainable management of their population. 展开更多
关键词 regeneration Dynamics Woody Species Abandoned Secondary Roads Forest Management unit
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Proportion of Grid-forming Wind Turbines in Hybrid GFM-GFL Offshore Wind Farms Integrated with Diode Rectifier Unit Based HVDC System 被引量:3
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作者 Yanqiu Jin Zheren Zhang Zheng Xu 《Journal of Modern Power Systems and Clean Energy》 2025年第1期87-101,共15页
This study analyzes the stability and reactive characteristics of the hybrid offshore wind farm that includes gridforming(GFM)and grid-following(GFL)wind turbines(WTs)integrated with a diode rectifier unit(DRU)based h... This study analyzes the stability and reactive characteristics of the hybrid offshore wind farm that includes gridforming(GFM)and grid-following(GFL)wind turbines(WTs)integrated with a diode rectifier unit(DRU)based high-voltage direct current(HVDC)system.The determination method for the proportion of GFM WTs is proposed while considering system stability and optimal offshore reactive power constraints.First,the small-signal stability is studied based on the developed linear model,and crucial factors that affect the stability are captured by eigenvalue analysis.The reactive power-frequency compensation control of GFM WTs is then proposed to improve the reactive power and frequency dynamics.Second,the relationship between offshore reactive power imbalance and the effectiveness of GFM capability is analyzed.Offshore reactive power optimization methods are next proposed to diminish offshore reactive load.These methods include the optimal design for the reactive capacity of the AC filter and the reactive power compensation control of GFL WTs.Third,in terms of stability and optimal offshore reactive power constraints,the principle and calculation method for determining the proportion of GFM WTs are proposed,and the critical proportion of GFM WTs is determined over the full active power range.Finally,case studies using a detailed model are conducted by timedomain simulations in PSCAD/EMTDC.The simulations verify the theoretical analysis results and the effectiveness of the proposed determination method for the proportion of GFM WTs and reactive power optimization methods. 展开更多
关键词 Offshore wind farm diode rectifier unit high-voltage direct current(HVDC) grid-forming(GFM)wind turbine grid-following(GFL)wind turbine
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Structural and functional damage to the hippocampal neurovascular unit in diabetes-related depression 被引量:28
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作者 Jian Liu Yu-Hong Wang +4 位作者 Wei Li Lin Liu Hui Yang Pan Meng Yuan-Shan Han 《Neural Regeneration Research》 SCIE CAS CSCD 2019年第2期289-297,共9页
Previous studies have shown that models of depression exhibit structural and functional changes to the neurovascular unit. Thus, we hypothesized that diabetes-related depression might be associated with damage to the ... Previous studies have shown that models of depression exhibit structural and functional changes to the neurovascular unit. Thus, we hypothesized that diabetes-related depression might be associated with damage to the hippocampal neurovascular unit. To test this hypothesis, neurons, astrocytes and endothelial cells were isolated from the brain tissues of rat embryos and newborn rats. Hippocampal neurovascular unit co-cultures were produced using the Transwell chamber co-culture system. A model of diabetes-related depression was generated by adding 150 mM glucose and 200 μM corticosterone to the culture system and compared with the neuron + astrocyte and astrocyte + endothelial cell co-culture systems. Western blot assay was used to measure levels of structural proteins in the hippocampal neurovascular unit co-culture system. Levels of basic fibroblast growth factor, angiogenic factor 1, glial cell line–derived neurotrophic factor, transforming growth factor β1, leukemia inhibitory factor and 5-hydroxytryptamine in the hippocampal neurovascular unit co-culture system were measured by enzyme-linked immunosorbent assay. Flow cytometry and terminal deoxynucleotidyl transferase(TdT)-mediated dUTP nick end labeling staining was used to assess neuronal apoptosis in the hippocampal neurovascular unit. The neurovascular unit triple cell co-culture system had better barrier function and higher levels of structural and secretory proteins than the double cell co-culture systems. In comparison, in the model of diabetes-related depression, the neurovascular unit was damaged with decreased barrier function, poor structural integrity and impaired secretory function. Moreover, neuronal apoptosis was markedly increased, and 5-hydroxytryptamine levels were reduced. These results suggest that diabetes-related depression is associated with structural and functional damage to the neurovascular unit. Our findings provide a foundation for further studies on the pathogenesis of diabetes-related depression. 展开更多
关键词 nerve regenerATION hippocampus neurovascular unit neurons astrocytes brain microvascular cells cell culture co-culture diabetes-related DEPRESSION hyperglycemia corticosterone neural regenerATION
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Houshiheisan compound prescription protects neurovascular units after cerebral ischemia 被引量:9
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作者 Haizheng Wang Lei Wang +3 位作者 Nan Zhang Qi Zhang Hui Zhao Qiuxia Zhang 《Neural Regeneration Research》 SCIE CAS CSCD 2014年第7期741-748,共8页
Houshiheisan is composed of wind-dispelling (chrysanthemun fower, divaricate saposhnikovia root, Manchurian wild ginger, cassia twig, Szechwan lovage rhizome, and platycodon root) and deficiency-nourishing (ginseng... Houshiheisan is composed of wind-dispelling (chrysanthemun fower, divaricate saposhnikovia root, Manchurian wild ginger, cassia twig, Szechwan lovage rhizome, and platycodon root) and deficiency-nourishing (ginseng, Chinese angelica, large-head atractylodes rhizome, Indian bread, and zingiber) drugs. In this study, we assumed these drugs have protective effects against cerebral ischemia, on neurovascular units. Houshiheisan was intragastrically administered in a rat model of focal cerebral ischemia. Hematoxylin-eosin staining, transmission electron microscopy, immu- nofluorescence staining, and western blot assays showed that Houshiheisan reduced pathological injury to the ischemic penumbra, protected neurovascular units, visibly up-regtflated neuronal nuclear antigen expression, and down-regulated amyloid precursor protein and amyloid-[3 42 expression. Wind-dispelling and deficiency-nourishing drugs maintained NeuN expression to varying degrees, but did not affect amyloid precursor protein or amyloid-~ 42 expression in the ischemic penumbra. Our results suggest that the compound prescription Houshiheisan effectively suppresses abnormal amyloid precursor protein accumulation, reduces amyloid substance depo- sition, maintains stabilization of the internal environment of neurovascular units, and minimizes injury to neurovascular units in the ischemic penumbra. 展开更多
关键词 nerve regeneration brain injury cerebral ischemia Houshiheisan wind-dispelling dru-gs deficiency-nourishing drugs neurovascular units amyloid precursor protein jS-amyloid neuronalnuclear antigen NSFC grant neural regeneration
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Evaluation of vitamin D level in patients from neurosurgical intensive care unit
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作者 Ho Jun Yi Je Hoon Jeong +3 位作者 Eun-Sun Jin Il Young Shin Hyung Sik Hwang Seung-Myung Moon 《Neural Regeneration Research》 SCIE CAS CSCD 2013年第16期1528-1534,共7页
Vitamin D plays an important role in maintaining normal bone metabolism. Recent studies have suggested that vitamin D influences many other physiological processes, including muscle function, cardiovascular homeostasi... Vitamin D plays an important role in maintaining normal bone metabolism. Recent studies have suggested that vitamin D influences many other physiological processes, including muscle function, cardiovascular homeostasis, nerve function, and immune response. Furthermore, accumulated evidence suggests that vitamin D also mediates the immune system response to infection. Critical neurosurgical patients have higher infection and mortality rates. To correlate vitamin D deficiency to the immunological status of neurosurgical intensive care unit patients, we detected serum vitamin D level in 15 patients with clinically suspected infection and 10 patients with confirmed infection. Serum level of 25-hydroxyvitamin D, the primary circulating form of vitamin D, was significantly decreased in patients with suspected or confirmed infection after a 2-week neurosurgical intensive care unit hospitalization, while serum level of 1,25-dihydroxyvitamin D, the active form of vitamin D, was significantly decreased in patients after a 4-week neurosurgical intensive care unit hospitalization. These findings suggest that vitamin D deficiency is linked to the immunological status of neurosurgical intensive care unit patients and vitamin D supplementation can improve patient's immunological status. 展开更多
关键词 neural regeneration vitamin D white blood cell immune deficiency infectious diseases intensivecare unit NEUROSURGERY NEUROregenerATION
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Phenotypic changes of human cells in human-rat liver during partial hepatectomy-induced regeneration
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作者 Yan Sun Dong Xiao +4 位作者 Hong-An Li Jin-Fang Jiang Qing Li Ruo-Shuang Zhang Xi-Gu Chen 《World Journal of Gastroenterology》 SCIE CAS CSCD 2009年第29期3611-3620,共10页
AIM: To examine the human hepatic parenchymal and stromal components in rat liver and the phenotypic changes of human cells in liver of human-rat chimera (HRC) generated by in utero transplantation of human cells d... AIM: To examine the human hepatic parenchymal and stromal components in rat liver and the phenotypic changes of human cells in liver of human-rat chimera (HRC) generated by in utero transplantation of human cells during partial hepatectomy (PHx)-induced liver regeneration. METHODS: Human hepatic parenchymal and stromal components and phenotypic changes of human cells during liver regeneration were examined by flow oytometry, in situ hybridization and immunohistochemistry. RESULTS: ISH analysis positive cells in hepatic demonstrated human Aluparenchyma and stroma of recipient liver. Functional human hepatocytes generated in this model potentially constituted human hepatic functional units with the presence of donor-derived human endothelial and biliary duct cells in host liver. Alpha fetoprotein (AFP)^+, CD34^+ and CD45^+ cells were observed in the chimeric liver on day 10 after PHxinduced liver regeneration and then disappeared in PHx group, but not in non-PHx group, suggesting that dynamic phenotypic changes of human cells expressing AFP, CD34 and CD45 cells may occur during the chimeric liver regeneration. Additionally, immunostaining for human proliferating cell nuclear antigen (PCNA) showed that the number of PCNA-positive cells in the chimeric liver of PHx group was markedly increased, as compared to that of control group, indicating that donor-derived human cells are actively proliferated during PHx-induced regeneration of HRC liver. CONCLUSION: HRC liver provides a tool for investigating human liver regeneration in a humanized animal model. 展开更多
关键词 Human-rat chimera Humanized liver Human hepatocyte-like cells Humanized hepaticfunctional unit Partial hepatectomy model Liver regeneration
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基于二极管整流单元的海上风电柔性低频送出系统黑启动策略 被引量:3
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作者 黄莹 黄小威 +1 位作者 肖晃庆 刘涛 《高电压技术》 北大核心 2025年第1期346-355,I0039,共11页
在基于二极管整流单元(diode rectifier unit,DRU)的海上风电柔性低频送出系统中,DRU无法向海上风电场传输有功功率,需要额外的黑启动电源为风电机组提供启动所需的初始能量。为此,提出了一种采用辅助换流器作为黑启动电源的海上风电柔... 在基于二极管整流单元(diode rectifier unit,DRU)的海上风电柔性低频送出系统中,DRU无法向海上风电场传输有功功率,需要额外的黑启动电源为风电机组提供启动所需的初始能量。为此,提出了一种采用辅助换流器作为黑启动电源的海上风电柔性低频送出系统黑启动策略。首先,介绍了基于DRU的海上风电柔性低频送出系统的拓扑结构与风电机组稳态时的构网型控制策略。然后,基于上述控制策略设计了辅助换流器与风电机组的黑启动策略。在此基础上,分析了辅助换流器容量的选择方法。最后,在时域仿真软件PSCAD/EMTDC上搭建了相应的仿真模型,对系统的黑启动过程进行仿真,仿真中海上风电场所有电气量均能平稳达到正常运行前的状态。仿真结果表明,所提黑启动策略可以实现基于DRU的海上风电柔性低频送出系统的平滑启动。 展开更多
关键词 海上风电 低频交流输电 二极管整流单元 辅助换流器 构网型风电机组 黑启动
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资源潜力视角下城市更新单元划分方法——以重庆市渝中区为例
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作者 李和平 张荣明 《城市规划》 北大核心 2025年第8期71-84,共14页
城市更新由“散点更新”逐渐转向“片区统筹更新”,城市更新单元作为统筹更新方式的基本边界、更新传导载体和更新实施的工具发挥了重要作用。但城市更新单元在划分中存在着“问题导向”思维弱化更新潜力发挥、空间评价与范围划分逻辑... 城市更新由“散点更新”逐渐转向“片区统筹更新”,城市更新单元作为统筹更新方式的基本边界、更新传导载体和更新实施的工具发挥了重要作用。但城市更新单元在划分中存在着“问题导向”思维弱化更新潜力发挥、空间评价与范围划分逻辑脱节等问题。基于资源潜力视角,解析了其具有的机会价值、空间度量、阈值判断等特征;探索性构建了“基于资源调查的更新潜力评估-基于非监督聚类划分单元边界-统筹资源潜力划定更新单元”的城市更新单元划分路径;并以重庆市渝中区更新单元划分和更新规划策略作为实证进行验证。 展开更多
关键词 城市更新 更新单元 资源潜力 重庆市渝中区 非监督空间聚类
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一种自适应残差卷积自编码网络及其故障诊断应用
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作者 潘天成 陈龙 +1 位作者 蒲春雷 陈志强 《机电工程》 北大核心 2025年第3期529-538,共10页
针对传统卷积自编码器(CAE)会将不同故障产生的相似信号进行相同的非线性变换,导致故障诊断准确率下降的问题,提出了一种自适应残差卷积自编码网络(ARCAE),并将其应用于滚动轴承故障诊断中。首先,在残差模块的基础上,引入了自适应参数... 针对传统卷积自编码器(CAE)会将不同故障产生的相似信号进行相同的非线性变换,导致故障诊断准确率下降的问题,提出了一种自适应残差卷积自编码网络(ARCAE),并将其应用于滚动轴承故障诊断中。首先,在残差模块的基础上,引入了自适应参数化修正线性单元(APReLU),建立了自适应残差模块(ARM),ARM可以对相似的输入特征进行自适应非线性变换,避免了特征的错误识别;其次,在CAE中嵌入多级ARM,构建了ARCAE,增加了CAE的深度,提取了更具鉴别性的深层次特征,同时有效防止了网络加深而造成的性能退化;最后,基于ARCAE建立了针对一维信号的故障诊断新方法,将其应用于无监督滚动轴承故障诊断中,并通过两个不同类型的实验,对上述方法的有效性进行了验证。研究结果表明:在恒定转速工况下,ARCAE的诊断准确率最高,平均准确率达到了97.05%,且标准差仅为0.007,远低于其他几种传统CAE网络;在变转速工况下,ARCAE模型诊断准确率仍然是最高的,平均准确率达到了93.25%,由此说明ARCAE具有较高的特征提取能力和分类准确率;此外,变转速工况下,由于转速变化导致不同状态的振动信号特征差异变大,诊断难度加大,但与其他几种传统CAE网络相比,ARCAE诊断准确率下降最少,仅为5.37%,说明ARCAE具有更强的鲁棒性和稳定性。 展开更多
关键词 滚动轴承 自适应残差卷积自编码网络 自适应参数化修正线性单元 自适应残差模块 无监督故障诊断 特征提取
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废酸再生装置SO_(2)低温氧化催化剂工业应用总结
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作者 徐翠翠 孙启洪 +3 位作者 潘红年 刘剑利 杨析宗 刘增让 《炼油技术与工程》 2025年第4期47-50,共4页
介绍了SO_(2)低温氧化催化剂LC-01的工业生产及在某炼油厂烷基化废酸装置的工业应用情况。在工业生产装置上进行了LC-01催化剂的工业试生产。该催化剂具有良好的制备重复性及活性。与进口催化剂相比较,LC-01催化剂具有更高的比表面积和... 介绍了SO_(2)低温氧化催化剂LC-01的工业生产及在某炼油厂烷基化废酸装置的工业应用情况。在工业生产装置上进行了LC-01催化剂的工业试生产。该催化剂具有良好的制备重复性及活性。与进口催化剂相比较,LC-01催化剂具有更高的比表面积和孔体积,灰分明显低于进口催化剂。在某炼油厂烷基化废酸装置完成了催化剂的装填及开工,装置开工后三级反应器(R-355)运行稳定,各项参数均在正常范围内,尾气SO_(2)的质量浓度稳定低于1 mg/m^(3),LC-01催化剂运行良好。装置稳定运行两个月后,开展了首次工业应用标定,标定期间R-355入口SO_(2)的质量浓度在41~55 mg/m^(3),出口SO_(2)的质量浓度小于1 mg/m^(3);LC-01催化剂SO_(2)转化率在98%以上,平均转化率为99.07%;高架源SO_(2)排放稳定低于0.58mg/m^(3),满足环保法规要求。LC-01催化剂运行良好,可以满足装置使用要求,实现催化剂的国产化替代。 展开更多
关键词 废酸再生装置 二氧化硫 低温氧化 LC-01催化剂 转化率 床层压力降 床层温度 氮氧化物
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远海风电轻型化直流送出技术综述 被引量:2
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作者 肖晃庆 甘慧辰 +2 位作者 黄莹 张利东 杨苹 《高电压技术》 北大核心 2025年第6期2702-2719,共18页
柔性直流输电技术是大规模远海风电并网的首选技术方案,然而柔性直流换流平台相较于传统电网换相型直流换流平台体积更大、重量更重,存在投资建设成本高昂的问题。该文从远海风电直流送出系统集电和输电2个层面出发,讨论了现有海上风电... 柔性直流输电技术是大规模远海风电并网的首选技术方案,然而柔性直流换流平台相较于传统电网换相型直流换流平台体积更大、重量更重,存在投资建设成本高昂的问题。该文从远海风电直流送出系统集电和输电2个层面出发,讨论了现有海上风电轻型化直流送出的主要技术方案和关键技术。其中,轻型化集电技术主要有中频交流汇集技术、直流汇集技术和无升压变压器交流汇集技术3类;轻型化输电技术主要有基于紧凑型模块化多电平换流器的柔性直流输电技术、基于二极管整流单元的高压直流送出技术和基于混合型整流器的高压直流送出技术3类。最后,指出了远海风电轻型化直流送出技术的未来发展趋势和关键技术问题,为低成本远海风电工程建设提供参考。 展开更多
关键词 远海风电 轻型化 高压直流送出 模块化多电平换流器 二极管整流器 混合整流器
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热源塔热泵甲酸钠防霜溶液冷冻再生方法研究
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作者 倪龙 韩崇 江辉民 《暖通空调》 2025年第6期88-98,共11页
在热源塔热泵实际运行过程中,溶液质量分数随运行时间的延长逐渐降低,其吸湿能力下降,冰点温度上升,进而对热源塔热泵的制热能力与稳定运行带来严重影响。因此,本文提出了配套热源塔热泵的甲酸钠防霜溶液冷冻再生机组,通过搭建实验台测... 在热源塔热泵实际运行过程中,溶液质量分数随运行时间的延长逐渐降低,其吸湿能力下降,冰点温度上升,进而对热源塔热泵的制热能力与稳定运行带来严重影响。因此,本文提出了配套热源塔热泵的甲酸钠防霜溶液冷冻再生机组,通过搭建实验台测试了该机组在预设工况下的再生性能表现,从结冰分离、溶质损失和余热利用效率3个方面评估了系统再生性能与热回收能力。结果表明,机组能够在5个再生循环中将稀溶液从初始质量分数13%提升至目标质量分数15%,平均分离比为34.8%;采用溶质回收循环后,溶质回收率为69.1%,溶质损失占比降为3.1%;在整个过程中,机组的有效热利用系数为1.56,除冰质量能耗比为0.332 kW·h/kg,具有较好的再生效率和较高的能效。 展开更多
关键词 热源塔热泵 甲酸钠 防霜 溶液冷冻再生机组 再生效率 热效能分析
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英国城市更新区识别中多重剥夺指数的应用与启示 被引量:1
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作者 朱雨溪 朱乐 阳建强 《国际城市规划》 北大核心 2025年第1期97-106,共10页
英国当前使用的多重剥夺指数是40余年持续研究开发的综合性指标,是其中央政府和地方政府各级部门划定更新区、制定更新政策和分配更新资金的重要依据,对改善相对贫困社区的物质环境、增加就业机会和提高公共服务水平具有十分积极的影响... 英国当前使用的多重剥夺指数是40余年持续研究开发的综合性指标,是其中央政府和地方政府各级部门划定更新区、制定更新政策和分配更新资金的重要依据,对改善相对贫困社区的物质环境、增加就业机会和提高公共服务水平具有十分积极的影响。本文首先梳理了三个不同阶段多重剥夺指数与城市更新相结合的典型政策与更新行动;其次,剖析了多重剥夺的理论基础以及指数构建的具体方法和内容;再次,重点聚焦该指数在大伦敦“区域—地方—社区”各级空间单元中对城市更新区识别与城市更新行动指引的应用方式;最后,具体结合中国国情提出三点建议,即建构社区层级数据库,识别辅助城市更新区,按需分配更新基金,以期为我国城市更新工作提供借鉴和启示。 展开更多
关键词 城市更新 城市更新区 多重剥夺指数 更新区识别 相对贫困 英国
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海上风电经DRU-VSC混合换流送出系统换相机理与谐波抑制研究 被引量:1
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作者 李哲锴 杨仁炘 +2 位作者 方梓熙 于浩天 蔡旭 《中国电机工程学报》 北大核心 2025年第10期3958-3972,I0033,共16页
将小功率辅助换流器与二极管不控整流单元(diode rectifier unit,DRU)并联以替代原本大容量的海上模块化多电平换流器,是降低海上风电场直流送出成本的重要技术路线之一。针对这一系统,目前的研究大多限于拓扑及暂稳态控制,对其谐波及... 将小功率辅助换流器与二极管不控整流单元(diode rectifier unit,DRU)并联以替代原本大容量的海上模块化多电平换流器,是降低海上风电场直流送出成本的重要技术路线之一。针对这一系统,目前的研究大多限于拓扑及暂稳态控制,对其谐波及无功特性的研究较少。为了解决这一问题,建立含海上风场、DRU及全控辅助换流器的三端送出系统,简化等值模型和详细等值模型,对系统的开关导通过程和换相机理进行分析,发现该系统中占主导地位的并非是电流谐波,而是公共耦合点的电压谐波;在此基础上,进一步分析系统交直流电感参数对谐波幅值的影响,验证模型的合理性并对参数设计提出指导;基于前述分析建模,提出海上风电经并联混合换流送出系统的谐波电压抑制策略;最后,通过仿真与硬件在环实验验证所提换相机理和谐波特性的正确性以及谐波电压抑制策略的有效性。 展开更多
关键词 海上风电场 二极管整流单元 低成本送出 混合换流器 谐波电压抑制
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经DRU-HVDC送出的海上风电场汇集网电气调节特性分析及集群构网控制策略 被引量:3
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作者 于浩天 蔡旭 +2 位作者 杨仁炘 杨明扬 汤广福 《中国电机工程学报》 北大核心 2025年第6期2318-2334,I0024,共18页
基于构网型风电场与二极管不控整流单元(diode rectifier unit,DRU)的低成本直流送出方案是目前大规模远海风电开发的热点问题。风电机组的构网控制策略是该送出方案的关键,针对现有风机构网策略控制率设计原理不完善、控制结构改造难... 基于构网型风电场与二极管不控整流单元(diode rectifier unit,DRU)的低成本直流送出方案是目前大规模远海风电开发的热点问题。风电机组的构网控制策略是该送出方案的关键,针对现有风机构网策略控制率设计原理不完善、控制结构改造难度大、缺乏同步机理分析等问题,提出使用电压/功率因数节点来刻画DRU的基频功率特性,并利用BP-神经网络实现考虑换流特性及多重化后的DRU节点特性拟合。在此基础上,通过节点-潮流关系揭示风电汇集网络的等效负荷特性、电压/频率构建机理和对风电机组控制率设计的要求。进而提出一种基于锁相环与频率-无功下垂实现自同步的机组网侧变换器集群构网控制策略,完善下垂增益的设计和机组间的同步机理,并采用阻抗法分析验证所提控制策略在系统不同工况的宽频交互稳定性。最后,通过PSCAD/EMTDC仿真验证分析建模的准确性和构网控制策略的有效性。 展开更多
关键词 海上风电 二极管不控整流单元 电压/功率因数节点 构网控制 宽频交互稳定性
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走向可持续更新:英国城市更新法规体系演进脉络、逻辑和启示 被引量:2
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作者 林赛南 唐萧萧 《自然资源学报》 北大核心 2025年第1期58-73,共16页
城市更新作为中国存量转型时期的重要战略,需要完整的法规体系支撑更新行动的有序开展。英国城市更新有较长的历史进程,能够为中国提供镜鉴。基于历史制度主义理论框架,参考英国政府官方网站发布的第一手资料,对20世纪60年代以来英国城... 城市更新作为中国存量转型时期的重要战略,需要完整的法规体系支撑更新行动的有序开展。英国城市更新有较长的历史进程,能够为中国提供镜鉴。基于历史制度主义理论框架,参考英国政府官方网站发布的第一手资料,对20世纪60年代以来英国城市更新法规体系的历史脉络进行了梳理,剖析其变迁背后的结构、历史、行动者逻辑。最后立足中国发展目标,提出完善城市更新体系的建议:完善“主干法+配套法”的更新法律体系,将可持续发展纳入政策顶层设计,更新模式转向“有为政府,多方参与”,鼓励以社区为核心的可持续微更新。与英国相比,中国在制度、公共利益和资金模式等方面具有特殊性,吸收国际经验,对完善和创新面向可持续更新的法规体系具有重要意义。 展开更多
关键词 城市更新 城市更新法规 英国 国际经验 历史制度主义 可持续更新
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基于改进灰狼优化-简单循环单元网络的整流二极管寿命预测
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作者 谢亮 柴琳 +1 位作者 段航 方德 《科学技术与工程》 北大核心 2025年第15期6360-6367,共8页
整流器作为电能变换功率模块的关键环节,广泛应用于变频器等供电系统设备中,其运行可靠性直接影响整个系统的运行状态。为提高整流器运行可靠性,需针对其中的敏感部件整流二极管进行寿命预测,提出一种由改进后的灰狼优化算法(grey wolf ... 整流器作为电能变换功率模块的关键环节,广泛应用于变频器等供电系统设备中,其运行可靠性直接影响整个系统的运行状态。为提高整流器运行可靠性,需针对其中的敏感部件整流二极管进行寿命预测,提出一种由改进后的灰狼优化算法(grey wolf optimization,GWO)优化简单循环单元(simple recurrent unit,SRU)网络超参数的预测模型。首先对二极管进行功率循环加速老化试验,对其特征参数进行分析,选取正向导通压降作为主要老化特征,其次采用改良策略后的GWO对SRU网络的学习率、隐藏层个数、迭代次数等超参数进行寻优,建立组合预测模型,最后将老化试验所得数据输入模型中进行训练以及验证,得到预测结果与其他模型对比。结果表明:本文模型具有更高的准确性,基于数据驱动的预测方法较传统分析建模方法提高了二极管寿命预测精度,进而提高了整流器工作可靠性。 展开更多
关键词 整流二极管 寿命预测 加速老化试验 简单循环单元 改进灰狼算法
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