基于虚拟电力系统稳定器的低频振荡抑制策略

基于虚拟同步发电机(VSG)控制的新能源机组虽可增强电网惯量及频率稳定性,但可能继承与同步机类似的低频振荡问题。针对该问题,首先基于单台VSG并网的线性化模型,构建了适用于VSG的Phillips-Heffron模型,借助阻尼转矩法挖掘了VSG低频振荡的诱发机理。进一步提出一种附加于VSG无功环节的虚拟电力系统稳定器(VPSS),并给出了控制结构及基于相位补偿法的参数设计过程。研究结果表明:VSG发生低频振荡是由于系统受扰后,虚拟功角的振荡信号经过虚拟励磁调节器对VSG机电振荡回路产生了负阻尼转矩。将所提VPSS接入系统可在几乎不影响振荡频率的前提下,实现0.1~3 Hz下VSG低频振荡的有效抑制。

黄土筑坝填方工程地质问题及处理措施分析

针对黄土地区的填方工程地质问题,以陕西铜川老虎沟填方工程为依托,通过地质调查与测绘、地质勘探、原位测试及室内试验等勘察手段,对工程存在的工程地质问题进行了分析研究。结果表明:老虎沟填方工程存在不良地质作用、不稳定高边坡、地下水疏排及填方地基变形等工程地质问题,应对挖方区高边坡进行1∶0.5~1∶0.75的放坡,反压坡脚,并预留平台及马道;对填方区土料进行强夯、碾压,消除其湿陷性,建议设计最大干密度值为1.73 g/cm^(3),最优含水率值为17.3%,压实系数为0.95~0.97;挡土坝坝基建议挖除不良土层,挡土坝坝坡采取加筋土筑坡,坡度宜为45°,坡面需做好防冲刷防护措施;排水沟底宜选用粘性较小的黄土回填,地表采用粘性较大的红粘土回填,并在地表设置完善的排水系统;工后应结合土水监测方案,实时监测填方区内土水变化。该研究成果可为黄土地区类似填方工程建设提供参考。

基于数字孪生与多模型融合的多元负荷短期预测

针对多元负荷呈波动性和非线性特性导致预测模型稳定性差和精确度低等问题,提出一种基于数字孪生与多模型融合的多元负荷短期预测方法。首先,根据数字孪生体中气象和负荷信息,利用最大信息系数(MIC)分析多源数据信息间的耦合特性,基于数据时序性和周期性构建筛选信息特征。其次,采用自适应局部迭代滤波(ALIF)将历史多元负荷数据进行分解,得到不同频率下固有模态函数(IMF)分量。然后,采用核极限学习机(KELM)和双向长短期记忆网络(BiLSTM)预测高频和低频负荷分量,融合重构得到初始负荷短期预测结果。最后,利用数字孪生体补偿初始预测结果,得到最终负荷预测结果。仿真结果表明,与单预测模型及未基于数字孪生预测模型相比,所提方法具有更好的稳定性,能有效应对负荷波动变化和非线性,提升模型预测精度。

基于非侵入式负荷分解的家庭负荷两阶段超短期负荷预测模型

精细化负荷预测为制定家庭新型需求响应策略或能效管理模式提供了可靠的指导信息与理论基础,而负荷监测系统的广泛研究与发展为家庭设备层的负荷预测提供了有力的数据支撑。基于家庭负荷智能电能表集中数据,该文提出一种集分解-预测一体化的家庭负荷两阶段超短期负荷预测方法。该方法第一阶段提出了基于卷积神经网络(CNN)和双向门控单元(BiGRU)神经网络的非侵入式负荷分解(NILM)模型,解决了目前深度分解模型中特征提取不充分、分解精度低等问题。第二阶段构建了基于时间模式注意力机制(TPA)的时间卷积神经网络(TCN)负荷预测模型,深度挖掘NILM分解数据、集中负荷数据及日期特征等输入变量的深层交互信息,实现家庭设备层的负荷预测。算例部分通过UK-DALE数据集对所提方法进行验证,结果表明,该方法能够获得较高的分解精度和预测效果,为家庭负荷预测提供了良好的条件。

不同纳米黏土改良黄土试验结果对比分析

应用正交法设计试验,定量地分析了改良黄土抗压强度、抗剪强度指标以及渗透系数的影响因素和影响大小,得到了改良黄土的最优掺量。另外,通过扫描电镜试验探究纳米黏土材料对黄土的改良机理。研究表明:(1)影响改良黄土抗压强度因素有纳米黏土掺量、含水率和养护龄期,影响黏聚力、内摩擦角、渗透系数的因素有掺量、干密度、围压;(2)在不同影响因素下,纳米蒙脱土比凹凸棒土更能有效提高黄土的抗压强度;(3)当材料掺量小于等于1%时,凹凸棒土改良黄土的抗剪强度指标总体高于纳米蒙脱土抗剪强度指标,渗透系数则相反,而当掺量大于等于2%时,则相反;(4)当凹凸棒土材料掺加量为1%、纳米蒙脱土材料掺量为2%时,改良黄土表面最为致密,孔隙最少。

多腐蚀期龄浮式风电机组动态响应分析

腐蚀影响海上风电机组动态响应特性,为评估和预测多腐蚀期龄海上风电机组动态力学行为及疲劳寿命,基于Lagrange方程以及均匀腐蚀模型,建立腐蚀-浮式风电机组参数模型,采用数值分析方法分析多腐蚀期龄海上风电机组动态响应特征。结果表明,随着腐蚀期龄的逐渐累积,塔筒弯曲频率响应幅值成为影响塔顶位移运动的主要因素,塔基弯曲应力呈指数型增长,塔筒疲劳寿命将急剧降低。

U型框类零件双向拉深成形研究

针对U型框类零件成形质量不稳定、修整手工量大等问题,通过对零件结构的分析研究,借助CATIA对其进行了工艺补充面设计,并借助数值模拟对成形过程进行了仿真,研究了双向拉深成形工艺,设计了一种特有传力方式的双向拉深模具结构;选取凸凹模间隙、摩擦因数、压边力及拉深速度4个因素为优化变量,通过正交试验得出最优工艺参数组合,即压边力大小为30 kN、摩擦因数为0.1、凸凹模间隙为1.6 mm、拉深速度为6000 mm·s^(-1);最后针对拉深后回弹现象,对校正模进行了分析和设计并修整。生产试验表明,此模具结构可以很好地改善零件成形质量,提高效率并满足生产及设计要求。

环氧树脂涂层中添加含铝复合粉增强碳钢基材的防腐性

采用电化学阻抗谱(EIS)和电位极化(Tafel)试验,研究了在环氧树脂涂层中添加含铝粉末以增强碳钢基材的防腐性,含铝粉末包括纯铝、Al/CNT、Al/Al_(2)O_(3)、Al/CNT/Al_(2)O_(3)。用球磨法合成含2 wt.%碳纳米管、2 wt.%氧化铝纳米颗粒的复合粉末,然后以1 wt.%的浓度加入到环氧树脂涂层中。结果表明,由于环氧树脂复合涂层的防护性能增强,从而提高了其耐腐蚀性。研究还发现,Al/CNT/Al_(2)O_(3)复合添加剂的保护性能比其他添加剂更显著,因为其颗粒尺寸的减小和具有某些形状的颗粒,进一步减少了腐蚀环境通过涂层渗透的路径,避免了金属基底/涂层界面可能发生的反应。EP-Al/CNT/Al_(2)O_(3)保持了一次时间常数特性,并在整个暴露时间内表现出最高的阻抗和最强的稳定性。这些添加剂的存在增强了涂层,从而改善了涂层的屏障性能。

High Sensitivity Submicron Scale Temperature Sensor Based on Perovskite Nanoplatelet Lasers

Submicron scale temperature sensors are crucial for a range of applications,particularly in micro and na-noscale environments.One promising solution involves the use of active whispering gallery mode(WGM)microresonators.These resonators can be remotely excited and read out using free-space structures,simplifying the process of sensing.In this study,we present a submicron-scale temperature sensor with a remarkable sensitivity up to 185 pm/℃based on a trian-gular MAPbI3 nanoplatelet(NPL)laser.Notably,as temperature changes,the peak wavelength of the laser line shifts lin-early.This unique characteristic allows for precise temperature sensing by tracking the peak wavelength of the NPL laser.The optical modes are confined within the perovskite NPL,which measures just 85 nm in height,due to total internal reflec-tion.Our NPL laser boasts several key features,including a high Q of~2610 and a low laser threshold of about 19.8μJ·cm^(−2).The combination of exceptional sensitivity and ultra-small size makes our WGM device an ideal candidate for integration into systems that demand compact temperature sensors.This advancement paves the way for significant prog-ress in the development of ultrasmall temperature sensors,opening new possibilities across various fields.

延长组和龙马溪组典型页岩孔隙结构特征研究

页岩孔隙结构特征是反映其油气存储能力、流动能力和赋存状态的重要指标。为明确四川盆地和鄂尔多斯盆地典型页岩的孔隙结构特征,本文以重庆石柱、彭水地区的龙马溪组页岩和陕西宜君地区延长组长7段油页岩为研究对象,结合高压压汞和N_2吸附实验对3组页岩的孔隙结构进行了详细表征。基于分形理论中的Brooks-Corey模型和FHH模型,对大孔(介孔+宏孔)和微孔的不规则性和复杂性进行了深入探讨。结果表明:(1)龙马溪组和延长组页岩的孔隙形态均为墨水瓶形和平行板狭缝形;(2)孔径分布均呈多峰分布。龙马溪组页岩含微孔、介孔和宏孔,而延长组页岩以介孔和宏孔为主;(3)延长组页岩孔隙度、孔体积和分形维数均小于其他两个地区。因此,延长组页岩孔隙结构较为单一且致密性较好。研究成果可为两地页岩气的开发提供指导。

Transcriptional reprogramming during human osteoclast differentiation identifies regulators of osteoclast activity

Enhanced osteoclastogenesis and osteoclast activity contribute to the development of osteoporosis,which is characterized by increased bone resorption and inadequate bone formation.As novel antiosteoporotic therapeutics are needed,understanding the genetic regulation of human osteoclastogenesis could help identify potential treatment targets.This study aimed to provide an overview of transcriptional reprogramming during human osteoclast differentiation.Osteoclasts were differentiated from CD14+monocytes from eight female donors.RNA sequencing during differentiation revealed 8980 differentially expressed genes grouped into eight temporal patterns conserved across donors.These patterns revealed distinct molecular functions associated with postmenopausal osteoporosis susceptibility genes based on RNA from iliac crest biopsies and bone mineral density SNPs.Network analyses revealed mutual dependencies between temporal expression patterns and provided insight into subtype-specific transcriptional networks.The donor-specific expression patterns revealed genes at the monocyte stage,such as filamin B(FLNB)and oxidized low-density lipoprotein receptor 1(OLR1,encoding LOX-1),that are predictive of the resorptive activity of mature osteoclasts.The expression of differentially expressed G-protein coupled receptors was strong during osteoclast differentiation,and these receptors are associated with bone mineral density SNPs,suggesting that they play a pivotal role in osteoclast differentiation and activity.The regulatory effects of three differentially expressed G-protein coupled receptors were exemplified by in vitro pharmacological modulation of complement 5 A receptor 1(C5AR1),somatostatin receptor 2(SSTR2),and free fatty acid receptor 4(FFAR4/GPR120).Activating C5AR1 enhanced osteoclast formation,while activating SSTR2 decreased the resorptive activity of mature osteoclasts,and activating FFAR4 decreased both the number and resorptive activity of mature osteoclasts.In conclusion,we report the occurrence of transcriptional reprogramming during human osteoclast differentiation and identified SSTR2 and FFAR4 as antiresorptive G-protein coupled receptors and FLNB and LOX-1 as potential molecular markers of osteoclast activity.These data can help future investigations identify molecular regulators of osteoclast differentiation and activity and provide the basis for novel antiosteoporotic targets.

Bacterial communities and enzyme activities during litter decomposition of Elymus nutans leaf on the Qinghai-Tibet Plateau

The dominant plant litter plays a crucial role in carbon(C)and nutrients cycling as well as ecosystem functions maintenance on the Qinghai-Tibet Plateau(QTP).The impact of litter decomposition of dominant plants on edaphic parameters and grassland productivity has been extensively studied,while its decomposition processes and relevant mechanisms in this area remain poorly understood.We conducted a three-year litter decomposition experiment in the Gansu Gannan Grassland Ecosystem National Observation and Research Station,an alpine meadow ecosystem on the QTP,to investigate changes in litter enzyme activities and bacterial and fungal communities,and clarify how these critical factors regulated the decomposition of dominant plant Elymus nutans(E.nutans)litter.The results showed that cellulose and hemicellulose,which accounted for 95%of the initial lignocellulose content,were the main components in E.nutans litter decomposition.The litter enzyme activities ofβ-1,4-glucosidase(BG),β-1,4-xylosidase(BX),andβ-D-cellobiosidase(CBH)decreased with decomposition while acid phosphatase,leucine aminopeptidase,and phenol oxidase increased with decomposition.We found that both litter bacterial and fungal communities changed significantly with decomposition.Furthermore,bacterial communities shifted from copiotrophic-dominated to oligotrophic-dominated in the late stage of litter decomposition.Partial least squares path model revealed that the decomposition of E.nutans litter was mainly driven by bacterial communities and their secreted enzymes.Bacteroidota and Proteobacteria were important producers of enzymes BG,BX,and CBH,and their relative abundances were tightly positively related to the content of cellulose and hemicellulose,indicating that Bacteroidota and Proteobacteria are the main bacterial taxa of the decomposition of E.nutans litter.In conclusion,this study demonstrates that bacterial communities are the main driving forces behind the decomposition of E.nutans litter,highlighting the vital roles of bacterial communities in affecting the ecosystem functions of the QTP by regulating dominant plant litter decomposition.

The efficiency and safety evaluation of hemoglobin hydrolysate as a non-heme iron fortifier

Hemoglobin hydrolysate is derived from the enzymatic degradation of hemoglobin.This work aimed to evaluate whether hemoglobin hydrolysate promotes the absorption of non-heme iron and the safety of absorbed iron in mice by analyzing the iron binding content,iron circulation,and liver homeostasis.We found that hemoglobin hydrolysate promoted the absorption of non-heme iron with high efficiency in duodenum by spontaneously binding non-heme iron during digestion,and increased hepatic iron content by up-regulating divalent metal transporter 1,zinc transporter 14,but hepatic iron content only increased at 3 weeks.Duodenal iron entered the blood through ferroportin without restriction at 3 weeks,and excessive iron entered the liver and then affected the hepatocyte membranes permeability and lipid synthesis through oxidative stress.With the prolongation of dietary intervention,the up-regulated hepcidin acted on the ferroportin to restrict excess iron from entering the blood,and then the hepatic homeostasis recovered.In addition,hemoglobin hydrolysate enhanced the hepatic antioxidant capacity.Taken together,hemoglobin hydrolysate has a strong ability to promote the absorption of non-heme iron in vivo,and the absorbed iron is relatively safe due to the regulation of hepcidin.

Spatially engineering tri-layer nanofiber dressings featuring asymmetric wettability for wound healing

Inspired by the skin structure,an asymmetric wettability tri-layer nanofiber membrane(TNM)consisting of hydrophilic inner layer loaded with lidocaine hydrochloride(LID),hydrophobic middle layer with ciprofloxacin(CIP)and hydrophobic outer layer has been created.The hydrophobic outer layer endows the TNM with waterproof function and anti-adhesion from contaminants.The hydrophobic middle layer with CIP preserves long-term inhibition of bacteria growth and the hydrophilic inner layer with LID possesses optimal waterabsorbing capacity and air permeability.The TNM dramatically elevates the water contact angles from 10°(inner layer)to 120(outer layer),indicating an asymmetric wettability,which could directionally transport wound exudate within the materials and meanwhile maintain a comfortable and moist environment to promote wound healing.Furthermore,the sequential release of LID and CIP could relieve pain rapidly and achieve antibacterial effect in the long run,respectively.In addition,the TNM shows superior biocompatibility towards L929 cells.The in vivo results show the TNM could prevent infection,accelerate epithelial regeneration and significantly accelerate wound healing.This study indicates the developed TNM with asymmetrical wettability and synergetic drug release shows great potential as a wound dressing in clinical application.

An Improved Machine Learning Model for Pure Component Property Estimation

Information on the physicochemical properties of chemical species is an important prerequisite when performing tasks such as process design and product design.However,the lack of extensive data and high experimental costs hinder the development of prediction techniques for these properties.Moreover,accuracy and predictive capabilities still limit the scope and applicability of most property estimation methods.This paper proposes a new Gaussian process-based modeling framework that aims to manage a discrete and high-dimensional input space related to molecular structure representation with the group-contribution approach.A warping function is used to map discrete input into a continuous domain in order to adjust the correlation between different compounds.Prior selection techniques,including prior elicitation and prior predictive checking,are also applied during the building procedure to provide the model with more information from previous research findings.The framework is assessed using datasets of varying sizes for 20 pure component properties.For 18 out of the 20 pure component properties,the new models are found to give improved accuracy and predictive power in comparison with other published models,with and without machine learning.

Furfural residues derived nitrogen-sulfur co-doped sheet-like carbon: An excellent electrode for dual carbon lithium-ion capacitors

The state-of-the-art lithium-ion capacitors (LICs),consisting of high-capacity battery-type anode and high-rate capacitor-type cathode,can deliver high energy density and large power density when comparing with traditional supercapacitors and lithium-ion batteries,respectively.However,the ion kinetics mismatch between cathode and anode leads to unsatisfied cycling lifetime and anode degradation.Tremendous efforts have been devoted to solving the abovementioned issue.One promising strategy is altering high conductive hard carbon anode with excellent structural stability to match with activated carbon cathode,assembling dual-carbon LIC.In this contribution,one-pot in-situ expansion and heteroatom doping strategy was adopted to prepare sheet-like hard carbon,while activated carbon was obtained involving activation.Ammonium persulfate was used as expanding and doping agent simultaneously.While furfural residues (FR) were served as carbon precursor.The resulting hard carbon (FRNS-HC) and activated carbon (FRNS-AC)show excellent electrochemical performance as negative and positive electrodes in a lithium-ion battery (LIB).To be specific,374.2 m Ah g^(-1)and 123.1 m Ah g^(-1)can be achieved at 0.1 A g^(-1)and 5 A g^(-1)when FRNS-HC was tested as anode.When combined with a highly porous carbon cathode (S_(BET)=2961 m^(2)g^(-1)) synthesized from the same precursor,the LIC showed high specific energy of147.67 Wh kg^(-1)at approximately 199.93 W kg^(-1),and outstanding cycling life with negligible capacitance fading over 1000 cycles.This study could lead the way for the development of heteroatom-doped porous carbon nanomaterials applied to Li-based energy storage applications.

太阳能电池导电银浆研究进展

大力推进新能源的使用有助于我国早日实现“双碳”目标,太阳能电池能够将太阳能直接转化为电能,是最早将新能源进行利用的设备之一。具有优良导电性和印刷性的导电银浆成为太阳能电池的首选电极材料,其主要由银粉、玻璃粉、有机载体及优化性能的其他添加剂等组成,其性能直接影响着太阳能电池的效率。文章重点介绍了太阳能电池导电银浆的组成以及制备方法,总结了目前银浆市场的发展情况以及导电银浆未来的发展趋势,提出了我国导电银浆行业的问题及相应建议,希望对国产银浆的发展具有一定的指导。

Confirmation of a Sub-Saturn-size Transiting Exoplanet Orbiting a G Dwarf:TOI-1194 b and a Very Low Mass Companion Star: TOI-1251 B from TESS

We report the confirmation of a sub-Saturn-size exoplanet,TOI-1194 b,with a mass of about 0.456+0.055-0.051M_(J),and a very low mass companion star with a mass of about 96.5±1.5 MJ,TOI-1251 B.Exoplanet candidates provided by the Transiting Exoplanet Survey Satellite(TESS)are suitable for further follow-up observations by ground-based telescopes with small and medium apertures.The analysis is performed based on data from several telescopes worldwide,including telescopes in the Sino-German multiband photometric campaign,which aimed at confirming TESS Objects of Interest(TOIs)using ground-based small-aperture and medium-aperture telescopes,especially for long-period targets.TOI-1194 b is confirmed based on the consistent periodic transit depths from the multiband photometric data.We measure an orbital period of 2.310644±0.000001 days,the radius is 0.767+0.045-0.041RJ and the amplitude of the RV curve is 69.4_(-7.3)^(+7.9)m s^(-1).TOI-1251 B is confirmed based on the multiband photometric and high-resolution spectroscopic data,whose orbital period is 5.963054+0.000002-0.000001days,radius is 0.947+0.035-0.033 R_(J) and amplitude of the RV curve is 9849_(-40)^(+42)ms^(-1).

含高比例新能源的电力系统低频振荡分析与抑制综述

随着碳达峰、碳中和目标的持续推进,由火力发电主导的传统电力系统逐步转变为以新能源为主体的新型电力系统.然而,高比例新能源的接入不仅会改造传统机组的低频振荡特征,亦会引入"类机电振荡".为深入综述该问题,从电力系统潮流、惯量和动态交互的角度,分析了新能源并网对低频振荡的本质影响因素.针对不同的低频振荡类型,系统梳理了对应的产生机理及分析方法.进一步地,在新型电力系统"源-网-荷-储"架构下,对比分析了各类低频振荡抑制方法及其作用效果.最后,针对低频振荡影响因素、振荡机理及其分析与抑制方法的最新研究成果进行总结与展望.

海岸带滨海湿地蓝碳管理的研究进展

【研究目的】自2009年“蓝碳”这一概念首次被提出以来,海岸带蓝碳生境在封存大气CO_(2)中的重要作用越来越受到世界各国环境科学家、社会科学家和经济学家的关注,如何有效管理海岸带蓝碳成为热门话题之一。【研究方法】基于近些年来国内外对海岸带湿地蓝碳管理的研究进展,本文系统梳理了海岸带湿地蓝碳的储量和分布情况,并总结了影响海岸带蓝碳生境及其碳库保存的主要因素。【研究结果】中国海岸带地区滨海湿地的蓝碳总量和碳汇潜力巨大,但随着海岸带地区开发越发频繁,已对海岸带蓝碳碳汇能力造成了巨大的影响。【结论】本文提出需要综合环境科学、社会科学和经济学,强化已有蓝色碳汇的保护和管理,加强对未来新增蓝碳碳汇的潜力评价,以此提升中国在碳循环、全球气候变化以及碳减排增汇等方面研究的国际地位,同时为国家相关应对策略与政策提供科学依据,并能为近来实施的滨海湿地修复工程提供有力支撑。