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关中平原耕地RS影像精准提取方法研究

河南科技 2024年第9期51卷 96-100页

作者：徐清昊周浩浩长安大学土地工程学院陕西西安710061

【目的】高效获取大面积耕地影像分布数据,助力关中平原地区耕地保护动态监测和管理。【方法】以陕西省西安市临潼区为研究区,基于SNAP平台和ENVI处理软件,使用监督分类中的最大似然分类法对哨兵二号高分辨率遥感影像耕地RS(Remote Sens... 详细信息

【目的】高效获取大面积耕地影像分布数据,助力关中平原地区耕地保护动态监测和管理。【方法】以陕西省西安市临潼区为研究区,基于SNAP平台和ENVI处理软件,使用监督分类中的最大似然分类法对哨兵二号高分辨率遥感影像耕地RS(Remote Sensing)遥感数据进行识别提取,获取耕地空间分布及面积等地理信息。【结果】提取耕地总面积为411.57 km2,主要分布于临潼区北部相桥、交口、栋阳等街道及中东部何寨、零口街道等平缓地区,与官方统计面积相近,误差仅为0.92%,提取总体分类精度为96.07%,Kappa系数为0.94,符合精度要求。【结论】通过最大似然分类法提取耕地结果与实际数据较为贴合,证明最大似然分类法在实际耕地地类识别检测应用中有着较高的匹配度,可以较为精准地实现土地利用类型识别。

关键词：最大似然分类法 Sentinel-2高分遥感影像耕地 ENVI

组织工程血管构建过程中平滑肌细胞增殖变化及代谢模式

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中国组织工程研究 2024年第7期28卷 1043-1049页

作者：梅静怡刘江肖聪刘鹏周浩浩林展翼华南理工大学生物科学与工程学院广东省广州市510006 南方医科大学附属广东省人民医院(广东省医学科学院) 广东省广州市510080 先进制造科学与技术广东省实验室(季华实验室) 广东省佛山市528200 华南理工大学医学院广东省广州市510006

背景:将种子细胞接种于三维支架材料上然后在生物反应器中进行三维培养是一种常见的体外组织工程培养手段,但是生物工程血管构建过程中的细胞增殖变化及代谢模式尚不清楚。目的:探究利用体外生物反应器进行生物血管组织构建过程中细胞... 详细信息

背景:将种子细胞接种于三维支架材料上然后在生物反应器中进行三维培养是一种常见的体外组织工程培养手段,但是生物工程血管构建过程中的细胞增殖变化及代谢模式尚不清楚。目的:探究利用体外生物反应器进行生物血管组织构建过程中细胞耗氧等代谢变化及其原因。方法:以自主搭建的血管生物反应器系统为平台,牛血管壁平滑肌细胞为种子细胞,常规CO_(2)培养箱提供培养过程的外部气体环境。将种子细胞接种于管状多孔隙的聚乙醇酸支架材料上进行三维培养,全过程包括1周的静置期和7周脉动张应力刺激加载期。搭建一套非侵入式监测体系,采用光学溶解氧贴片法监测反应器中培养液溶解氧变化,并通过定期取样测定葡萄糖消耗量及乳酸生成量。采用CCK-8检测平滑肌细胞在聚乙醇酸三维支架材料上增殖情况,通过烟酰胺腺嘌呤二核苷酸的氧化态与还原态比值(NAD^(+)/NADH)了解培养早期阶段细胞增殖与代谢状况,采用RT-qPCR、Western blot方法检测增殖相关基因(Ki67)及糖酵解相关基因(GLUT-1、LDHA)的表达。结果与结论:(1)从细胞加注到静置期结束(第1周)培养液的溶解氧水平为(4.314±0.380)mg/L,张应力刺激加载后(后7周)溶解氧水平逐步稳定在(1.960±0.866)mg/L,两者有明显变化(P<0.05);(2)细胞培养液中乳酸生成量与葡萄糖消耗量的比值Y_(L/G)在加注细胞后快速升高,第5天最高值高于1,随后缓慢下降至0.5(静置期Y_(L/G)均值为0.89,加压期均值为0.57,P<0.05);(3)CCK-8检测显示A_(450)值在细胞加注之后逐渐增大,第5天达到最高值3.17,之后缓慢下降;同时发现Ki67 mRNA在培养第3天上调最显著,之后下降,Ki67蛋白在第3-5天的相对表达量较高;(4)细胞加注后第5-7天NAD~+/NADH明显升高,糖酵解相关基因(GLUT-1、LDHA)表达上调同步改变,前5 d相对表达量较高;(5)结果提示:利用血管生物反应器构建组织工程血管早期,平滑肌细胞以增殖为主并呈现一种低耗氧的代谢特征,在脉动张应力刺激阶段呈现耗氧较高的代谢特征。

关键词：生物反应器组织工程血管平滑肌细胞聚乙醇酸溶解氧细胞增殖有氧糖酵解

基于改进GWO-LightGBM的磨煤机故障预警方法研究

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自动化仪表 2024年第2期45卷 106-110,115页

作者：陈思勤周浩豪茅大钧华能国际电力股份有限公司上海石洞口第二电厂上海200942 上海电力大学自动化工程学院上海201306

为提高燃煤电厂磨煤机运维效率、降低运维成本,对磨煤机故障预警进行了研究。创新性地提出一种基于改进灰狼优化(GWO)算法的轻量级梯度提升机(LightGBM)故障预警方法。通过建立LightGBM轴承温度预测模型获取磨煤机轴承温度阈值,并引入改... 详细信息

为提高燃煤电厂磨煤机运维效率、降低运维成本,对磨煤机故障预警进行了研究。创新性地提出一种基于改进灰狼优化(GWO)算法的轻量级梯度提升机(LightGBM)故障预警方法。通过建立LightGBM轴承温度预测模型获取磨煤机轴承温度阈值,并引入改进GWO算法优化模型超参数,以提高算法效率和性能。试验结果表明,改进GWO-LightGBM算法相比支持向量机(SVM)等传统算法具有更高的精度和更优的泛化能力。通过实际故障案例证明,该方法能够提前2 h对磨煤机进行早期故障预警。该方法对燃煤电厂磨煤机安全运维具有指导意义。

关键词：燃煤电厂磨煤机故障预警改进灰狼优化算法轻量级梯度提升机滑动窗口法 Halton

Characterization of an ionic liquid electrospray thruster with a porous ceramic emitter

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Plasma Science and Technology 2020年第9期22卷 66-74页

作者： Chong CHEN Maolin CHEN haohao zhou Combustion Internal Flow and Thennal-Structure LaboratoryNorthwestern Polytechnical UniversityXi’an 710072People’s Republic of China

An ionic liquid(IL)electrospray thruster was developed for application in micro-nano satellites or gravitational wave *** thruster employed a porous ceramic emitter with seven emitter strips located on its emission *** any liquid-supply device,IL was delivered through porous media to emitter strips via capillary *** emission sites then formed at the tip of each strip.A charged beam of up to 350μA(with a current density of 540μA cm^(-2))was stably produced in the negative ***,in the positive mode,a corona was observed which could prevent the thruster from emitting larger current.A time-of-flight mass spectrometer with significantly improved signal-to-noise ratio was built,which was used to obtain the mass distribution of the beam of the thruster.A retarding potential analysis was also *** test results showed that the thruster worked in the pure-ion regime,and delivered a maximum thrust of 67.1μN with specific impulses of 3952 s and 3117 s in the positive and negative modes,respectively.

关键词： electrospray thruster time-of-flight(TOF) retarding potential analysis(RPA)

磨削深度对γ-TiAl合金表面完整性和疲劳性能的影响

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金属学报 2024年第2期60卷 261-272页

作者：倪明杰刘仁慈周浩浩杨超葛术宇刘冬史凤岭崔玉友杨锐中国科学院金属研究所师昌绪先进材料创新中心沈阳110016 中国科学技术大学材料科学与工程学院沈阳110016 中国航发沈阳黎明航空发动机有限责任公司沈阳110043 中国航发商用航空发动机有限责任公司上海200241

γ-TiAl合金部件需要磨削加工以保证其装配精度,而低塑性金属间化合物γ-TiAl合金的力学性能对磨削表面完整性极为敏感。本工作研究了磨削深度对γ-TiAl合金样品表面形貌、表层显微组织、显微硬度等表面完整性参数及最终疲劳性能的影响... 详细信息

γ-TiAl合金部件需要磨削加工以保证其装配精度,而低塑性金属间化合物γ-TiAl合金的力学性能对磨削表面完整性极为敏感。本工作研究了磨削深度对γ-TiAl合金样品表面形貌、表层显微组织、显微硬度等表面完整性参数及最终疲劳性能的影响。结果表明,0.5 mm及以上深度磨削样品表面易产生裂纹,而0.2 mm及以下深度磨削样品表面完好,这与磨削变形热温升导致的冷却收缩拉应力过大有关。随着磨削深度增大,粗糙度参数的轮廓算术平均偏差(R_(a))和微观不平度的十点平均高度(R_(z))增大,偏度(R_(sk))减小。表层γ+α_(2)片层沿磨削方向弯曲变形,相应变形层厚度随着磨削量增大而增大,而显微硬度由表及里先减小后增大。γ-TiAl合金650℃加载440 MPa旋转弯曲疲劳寿命随着磨削深度增大而减小,磨削深度0.05 mm的样品疲劳寿命大于106cyc,磨削深度0.2 mm的样品疲劳寿命约为104cyc,其断口裂纹源可观察到磨削痕迹,这与其表面沟槽应力集中有关。γ-TiAl合金疲劳寿命随着R_(z)的增大而减小,2者呈非线性关系;当R_(z)小于4μm时,疲劳寿命稳定在106cyc以上。

关键词： γ-TiAl 磨削表面完整性粗糙度显微组织疲劳性能

Spatial Patterns of LULC and Driving Forces in the Transnational Area of Tumen River:A Comparative Analysis of the Sub-regions of China,the DPRK,and Russia

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Chinese Geographical Science 2020年第4期30卷 588-599页

作者： NAN Ying WANG Bingbing ZHANG Da LIU Zhifeng QI Dekang zhou haohao College of Geography and Ocean Sciences Yanbian UniversityYanji Jilin133002China Center for Human-Environment System Sustainability(CHESS) State Key Laboratory of Earth Surface Processes and Resource Ecology(ESPRE)Beijing Normal UniversityBeijing 100875China School of Natural Resources Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China

Understanding the spatial patterns of land-use and land-cover(LULC)and their driving forces in transnational areas is important for the sustainable development of these ***,the spatial patterns of LULC and their driving forces across multiple scales are poorly understood in transnational *** this study,we analyzed the spatial patterns of LULC and driving forces in the transnational area of Tumen River(TATR)in 2016 across two scales:the entire region and the sub-regions of China,the Democratic People’s Republic of Korea(DPRK),and *** showed that the LULC was dominated by broadleaf forest and dry farmland in the TATR in 2016,which accounted for 66.86%and 13.60%of the entire region,***,the LULC in the three sub-regions exhibited noticeable *** the Chinese and the DPRK’s sub-regions,the area of broadleaf forest was greater than those for the other LULC types,while the Russian sub-region was dominated by broadleaf forest and *** spatial patterns of LULC were mainly influenced by topography,climate,soil properties,and human *** addition,the driving forces of the spatial patterns of LULC in the TATR had an obvious scaling ***,we suggest that effective policies and regulations with cooperation among China,the DPRK,and Russia are needed to plan the spatial patterns of LULC and improve the sustainable development of the TATR.

关键词： land-use and land-cover(LULC) spatial pattern driving force transnational area of Tumen River

基于粒子群优化的面向数据异构的联邦学习方法

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计算机科学 2024年第6期51卷 391-398页

作者：徐奕成戴超凡马武彬吴亚辉周浩浩鲁晨阳国防科技大学信息系统工程重点实验室长沙410073

联邦学习是一种新兴的面向隐私保护的分布式机器学习框架,其核心特点是能够在不获取客户端原始数据的条件下实现分布式机器学习。客户端利用本地数据进行模型训练,然后将模型参数上传至服务端进行聚合,从而确保客户端数据始终得到保护... 详细信息

联邦学习是一种新兴的面向隐私保护的分布式机器学习框架,其核心特点是能够在不获取客户端原始数据的条件下实现分布式机器学习。客户端利用本地数据进行模型训练,然后将模型参数上传至服务端进行聚合,从而确保客户端数据始终得到保护。在此过程中,存在频繁的参数传输导致的通信成本高昂问题和各客户端所拥有的非独立同分布异构数据问题,两者严重制约了联邦学习的应用。针对上述问题,提出了一种基于粒子群优化的面向数据异构的联邦学习方法——FedPSG,将客户端传输到服务器的数据形式由模型参数转变为模型分值,在每轮训练中只需要少部分客户端向服务器上传模型参数,从而降低通信成本;同时,提出了一种模型再训练策略,使用服务器数据对全局模型进行二次迭代训练,通过缓解数据异构问题对联邦学习的影响来进一步提升模型性能。模拟不同的数据异构环境,在MNIST,FashionMNIST与CIFAR-10数据集上进行实验,结果表明FedPSG能够有效提高模型在不同数据异构环境下的准确率,并且验证了模型再训练策略能有效解决客户端数据异构问题。

关键词：联邦学习粒子群算法通信成本数据异构隐私保护

Spatio-temporal Variation of Water Heat Flux Using MODIS Land Surface Temperature Product over Hulun Lake,China During 2001–2018

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Chinese Geographical Science 2020年第6期30卷 1065-1080页

作者： ZHAO Boyu DU Jia SONG Kaishan Pierre-Andre JACINTHE XIANG Xiaoyun zhou haohao YANG Zhichao ZHANG Liyan GUO Pingping Northeast Institute of Geography and Agroecology Chinese Academy of SciencesChangchun 130102China Department of Earth Sciences Indiana University-Purdue University IndianapolisIN 46202USA University of Science and Technology Liaoning Anshan 114051China Jinan District Bureau of Natural Resources and Planning Fuzhou 350002China Minjiang River Estuary Wetland National Nature Reserve Administrative Office Fuzhou 350002China

Heat flux is important for studying interactions between atmosphere and *** heat exchange between air-water interfaces is one of the important ways to govern the temperature of the water *** exchange between the air-water interfaces and the surrounding environment is completed by solar radiation,conduction,and evaporation,and all these processes mainly occur at the air-water *** Lake was the biggest lake which is also an important link and an indispensable part of the water cycle in Northeast *** study mapped surface energy budget to better understand spatial and temporal variations in Hulun Lake in China from 2001 to *** statistics were computed to build a historical time series of mean monthly heat flux at daytime and nighttime from June to September during 2001–*** sensing estimation methods we used was suitable for Hulun Lake(R2=0.81).At month scale,shortwave radiation and latent heat flux were decrease from June to ***,the maximum sensible heat flux appeared in *** longwave radiation was the largest in *** effective heat budget showed that Hulun Lake gained heat in the frost-free season with highest value in June(686.31 W/m2),and then steadily decreased to September(439.76 W/m2).At annual scale,net longwave radiation,sensible heat flux and latent heat flux all show significant growth trend from 2001 to 2018(P<0.01).Wind speed had the well correlation on sensible heat flux and latent heat *** surface temperature showed the highest coefficient in sensitivity analysis.

关键词： water surface temperature(WST) heat flux Moderate Resolution Imaging Spectroradiometer(MODIS) remote sensing Hulun Lake,China

Experimental study of a porous electrospray thruster with different number of emitterstrips

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Plasma Science and Technology 2021年第10期23卷 22-28页

作者： Hanwu JIA Maolin CHEN Xuhui LIU Chong CHEN haohao zhou Hao ZHAO Zhicong HAN Combustion Internal Flow and Thermal-Structure LaboratoryNorthwestern Polytechnical UniversityXi’an 710072People’s Republic of China Beijing institute of Control Engineering Beijing 100190People's Republic of China Aircraft Design Institute of AVIC Xi'an 710089People's Republic of China

The electrospray thruster is becoming popular in space propulsion due to its low power and high specific *** this work,an electrospray thruster based on a porous emitter was *** order to achieve larger and more stable thrust,the thruster was redesigned,and the influence of the space between strips on thrust was *** types of emitter were tested,and they had 1,3,4 and 14 emitter-strips on the emission surface of the same size *** to the experimental results,the maximum extraction voltage and emission current of the four thrusters are different under stable operational *** measured stable emission currents and extraction voltages were-500μA/-5000 V,-1570μA/-3800 V,-1200μA/-3800 V,and-650μA/-4500 V,*** the number of strips may not result in the emission current increasing,but changing the stable operational range of the emission current per strip and the extraction *** maximum stable operational extraction voltages of 3 and 4 emitter-strips are lower than those of 1 and 14 emitter-strips,but the emission currents are higher than those of 1 and 14 ***-of-flight mass spectrometry was used to analyze the mass distribution and obtain the performance of the thruster in the case of thrusters with 1 and 3 *** of their plumes were composed of very small ion cluster(the pure-ion regime),and their thrusts were 80.1μN,219.2μN with specific impulses of 5774 s,5047 s,respectively.

关键词： electrospray thruster TOF ionic liquid