检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

基于嵌入法与集成学习的线路工程造价预测

中国电力 2024年第5期57卷 251-260页

作者：叶煜明钱琪琪万正东张继钢中国南方电网有限责任公司广东广州510530 南方电网能源发展研究院有限责任公司广东广州510530

架空线路工程造价的准确预测对于工程建设质量及造价管控具有十分重要的意义。针对传统架空线路工程造价预测中遇到的特征维度过高、单一预测模型难以拟合复杂造价数据等问题,提出了基于嵌入法数据降维与集成学习的线路工程造价预测算... 详细信息

架空线路工程造价的准确预测对于工程建设质量及造价管控具有十分重要的意义。针对传统架空线路工程造价预测中遇到的特征维度过高、单一预测模型难以拟合复杂造价数据等问题,提出了基于嵌入法数据降维与集成学习的线路工程造价预测算法。首先通过嵌入法与极端梯度提升(extreme gradient boosting,XGBoost)模型对特征进行排序,筛选出对造价影响显著的特征完成数据降维。然后对XGBoost、随机森林、支持向量机(support vector machine,SVM)等模型进行融合,构成双层集成学习模型并对线路工程造价进行预测。最后基于某电网公司近年线路工程造价数据进行实例分析,分别与XGBoost、随机森林、SVM、极限学习机(extreme learning machine,ELM)与反向传播(back propagation,BP)神经网络等模型进行对比。实验表明预测结果的平均绝对百分比误差低于4%,优于其他单一模型,对线路工程造价控制研究具有较大价值。

关键词：输电线路造价预测集成学习数据降维嵌入法

Exploiting demand-side heterogeneous flexible resources in risk management of power system frequency

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第5期67卷 1612-1627页

作者： YAO Yu SONG YongHua ye ChengJin DING Yi ZHAO yuming College of Electrical Engineering Zhejiang UniversityHangzhou310027China State Key Laboratory of Internet of Things for Smart City University of MacaoMacao SAR519000China Shenzhen Power Supply Bureau Co. Ltd.Shenzhen518051China

More demand-side flexible resources(DFRs)are participating in the frequency regulation of renewable power systems,whose heterogeneous characteristics have a significant impact on the system frequency response.Consequently,selecting suitable DFRs poses a formidable challenge for independent system operators(ISO).In this paper,a reserve allocation methodology for heterogeneous DFRs is proposed to manage the risk of power system frequency.Firstly,a performance curve is developed to describe the cost,capacity,and response speed of DFRs.Moreover,a clustering method for multiple distributed DFRs is conducted to calculate the aggregated performance curves and uncertainty coefficients.Then,the frequency security criterion considering DFRs’performance is constructed,whose linearity makes it can be easily coupled into the system scheduling model and solved.Furthermore,a risk management model for DFRs considering frequency-chance-constraint is proposed to make a trade-off between cost and frequency security.Finally,the model is transformed into mixed integer second-order cone programming(MISOCP)and solved by the commercial solver.The proposed model is validated by the IEEE 30 and IEEE 118 bus systems.

关键词： demand-side heterogenous flexible resources risk management of power system frequency performance curve aggregation method mixed integer second-order cone programming

在线全文

学校读者我要写书评

暂无评论

三点弯曲法的PBGA封装实验测试(英文)

电子工业专用设备 2007年第3期36卷 30-38页

作者： Dennis Lau Y. S. Chan S. W. Ricky Lee Lifeng Fu yuming ye Sang Liu Electronic Packaging Laboratory Center for Advanced Microsystems Packaging Hong Kong University of Science and TechnologyClear Water Bay Kowloon Hong Kong China Huawei Technologies Co. Ltd. Bantien Shenzhen China

任何电子产品在进入市场之前的可靠性测试是十分重要的环节。为此,在之前的几十年中开发了多种类型的测试方法。一种广泛使用的测试方法便是线路板弯曲测试。进行可靠性测试的一个主要问题就是需要大量的测试样品,这是因为这种测试必须... 详细信息

任何电子产品在进入市场之前的可靠性测试是十分重要的环节。为此,在之前的几十年中开发了多种类型的测试方法。一种广泛使用的测试方法便是线路板弯曲测试。进行可靠性测试的一个主要问题就是需要大量的测试样品,这是因为这种测试必须重复进行直到获得一致并满意的测量结果。其测试样品的设计,组装工艺和测试程序需要花费长期的时间。如果可靠性测试结果不满意,测试样品需要重新设计、重新生产、重新测试,这从商业的观点来看成本过高且低效。为简化可靠性测试程序,提出了计算模拟的方法在前期设计阶段来预测印制板组装线的可靠性。在目前的研究中,可靠性测试采用了三点弯曲测试法。实现了有限元模式确认及关于该模式应用的2种情况研究。

关键词：印制板测试可靠性测试三点弯曲测试有限元模式应力分析

Commentary:Mammokine directs beige adipocytes to reserve energy for milk production in breast

在线全文

学校读者我要写书评

暂无评论

Acta Pharmaceutica Sinica B 2024年第3期14卷 1472-1476页

作者： Lina Tang Jianping ye Metabolic Disease Research Center Zhengzhou University Affiliated Zhengzhou Central HospitalZhengzhou 450007China Research Center for Basic Medicine Academy of Medical SciencesZhengzhou UniversityZhengzhou 450052China

Beige/brown adipocytes play a crucial role in regulating the body’s overall energy balance.The thermogenic function is under the influence of various tissues,including the brain,muscles,and liver.However,the breast t... 详细信息

关键词： Beige Breast Epitheliail cells scRNA-seq Thermogenesis

A modified stochastic model for LS+AR hybrid method and its application in polar motion short-term prediction

在线全文

学校读者我要写书评

暂无评论

Geodesy and Geodynamics 2024年第1期15卷 100-105页

作者： Fei ye Yunbin Yuan State Key Laboratory of Geodesy and Earth's Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430077China BeiDou High-precision Satellite Navigation and Location Service Hunan Engineering Research Center Hunan Institute of Geomatics Sciences and TechnologyChangsha 410007China Hunan Continuously Operating Reference Stations(HNCORS)Data Center Hunan Institute of Geomatics Sciences and TechnologyChangsha 410007China

Short-term(up to 30 days)predictions of Earth Rotation Parameters(ERPs)such as Polar Motion(PM:PMX and PMY)play an essential role in real-time applications related to high-precision reference frame conversion.Currently,least squares(LS)+auto-regressive(AR)hybrid method is one of the main techniques of PM prediction.Besides,the weighted LS+AR hybrid method performs well for PM short-term prediction.However,the corresponding covariance information of LS fitting residuals deserves further exploration in the AR model.In this study,we have derived a modified stochastic model for the LS+AR hybrid method,namely the weighted LS+weighted AR hybrid method.By using the PM data products of IERS EOP 14 C04,the numerical results indicate that for PM short-term forecasting,the proposed weighted LS+weighted AR hybrid method shows an advantage over both the LS+AR hybrid method and the weighted LS+AR hybrid method.Compared to the mean absolute errors(MAEs)of PMX/PMY sho rt-term prediction of the LS+AR hybrid method and the weighted LS+AR hybrid method,the weighted LS+weighted AR hybrid method shows average improvements of 6.61%/12.08%and 0.24%/11.65%,respectively.Besides,for the slopes of the linear regression lines fitted to the errors of each method,the growth of the prediction error of the proposed method is slower than that of the other two methods.

关键词： Stochastic model LS+AR Short-term prediction The earth rotation parameter(ERP) Observation model

Commentary:Gut microbiota reduce the risk of hyperuricemia and gout in the human body

在线全文

学校读者我要写书评

暂无评论

Acta Pharmaceutica Sinica B 2024年第1期14卷 433-435页

作者： Lin Wang Jianping ye Metabolic Disease Research Center Zhengzhou University Affiliated Zhengzhou Central HospitalZhengzhou 450007China Research Center for Basic Medicine Academy of Medical SciencesZhengzhou UniversityZhengzhou 450052China

Gout,a prevalent and painful metabolic disease often associated with obesity and aging,is caused by the deposition of urate crystals in joints,bones,or soft tissues1.Urate is an intermediate metabolite within the purine degradation pathway,predominantly derived from uric acid under physiological pH levels.Hyperuricemia occurs due to excessive uric acid production or insufficient excretion2,which is associated with various chronic diseases,including type 2 diabetes.

关键词： Uric acid Gout Microbiota Gut Uricase

Effects of microenvironment and biological behavior on the paracrine function of stem cells

在线全文

学校读者我要写书评

暂无评论

Genes & Diseases 2024年第1期11卷 135-147页

作者： Zhixin Xue Yunjun Liao ye Li The Department of Plastic and Cosmetic Surgery Nanfang HospitalSouthern Medical UniversityGuangzhouGuangdong 510515China

Mesenchymal stem cells(MSCs),the most well-studied cell type in the field of stem cell therapy,have multi-lineage differentiation and self-renewal potential.MsC-based thera-pies have been used to treat diverse diseases because of their ability to potently repair tissue and locally restore function.An increasing body of evidence demonstrates that paracrine func-tion is central to the effects of MsC-based therapy.Growth factors,cytokines,chemokines,extracellular matrix components,and extracellular vehicles all contribute to the beneficial ef-fects of MSCs on tissue regeneration and repair.The paracrine substances secreted by MSCs change depending on the tissue microenvironment and biological behavior.In this review,we discuss the bioactive substances secreted by MsCs depending on the microenvironment and biological behavior and their regulatory mechanisms,which explain their potential to treat human diseases,to provide new ideas for further research and clinical cell-free therapy.

关键词： Bioactive behavior Mesenchymal stem cells Microenvironment Paracrine Secretome

Building the toolbox for in vivo glia-to-neuron reprogramming

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第6期19卷 1171-1172页

作者： ye Xie Bo Chen Departments of Ophthalmology and Neuroscience Icahn School of Medicine at Mount Sinai

Unlike regenerative-competent species that possess a remarkable intrinsic capacity to replenish lost neurons and restore neurocircuits spontaneously, the central nervous system in adult mammals lacks the ability to compensate for the neuronal loss caused by neurodegenerative diseases or traumatic injuries resulting in permanent loss of functionality. Inspired by earlier discoveries that radial glia or astrocytes isolated from the postnatal cortex can generate neurons,

关键词： CONVERSION DISEASE

Complicated target recognition by archaeal box C/D guide RNAs

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2024年第4期67卷 631-644页

作者： Jiayin Wang Songlin Wu Keqiong ye Key Laboratory of RNA Science and Engineering CAS Center for Excellence in BiomacromoleculesInstitute of BiophysicsChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

Box C/D RNAs guide the site-specific formation of 2′-O-methylated nucleotides(Nm)of RNAs in eukaryotes and archaea.Although C/D RNAs have been profiled in several archaea,their targets have not been experimentally determined.Here,we mapped Nm in r RNAs,t RNAs,and abundant small RNAs(s RNAs)and profiled C/D RNAs in the crenarchaeon Sulfolobus islandicus.The targets of C/D RNAs were assigned by analysis of base-pairing interactions,in vitro modification assays,and gene deletion experiments,revealing a complicated landscape of C/D RNA-target interactions.C/D RNAs widely use dual antisense elements to target adjacent sites in r RNAs,enhancing modification at weakly bound sites.Two consecutive sites can be guided with the same antisense element upstream of box D or D′,a phenomenon known as doublespecificity that is exclusive to internal box D′in eukaryotic C/D RNAs.Several C/D RNAs guide modification at a single non-canonical site.This study reveals the global landscape of RNA-guided 2′-O-methylation in an archaeon and unexpected targeting rules employed by C/D RNA.

关键词： C/D RNA 2′-O-methylation archaea guide RNA RNA modification