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永磁同步电动机电磁振动特性及抑制措施

科学技术与工程 2024年第17期24卷 7148-7158页

作者：李永枭成豪杰唐旭马兆兴王瑞华青岛理工大学信息与控制工程学院青岛266520

电磁振动水平是永磁同步电动机的重要评价指标之一,为了有效抑制永磁同步电动机的电磁振动,首先建立了转子永磁体磁动势、定子绕组电流磁动势与定子齿槽相互作用产生的径向电磁力的解析分析模型。然后建立了电机的变参数矢量控制系统的... 详细信息

电磁振动水平是永磁同步电动机的重要评价指标之一,为了有效抑制永磁同步电动机的电磁振动,首先建立了转子永磁体磁动势、定子绕组电流磁动势与定子齿槽相互作用产生的径向电磁力的解析分析模型。然后建立了电机的变参数矢量控制系统的场路耦合联合分析模型,以一台11 kW内置式永磁同步电动机为样机,利用机械阻抗法得到了电机主要低阶电磁力产生的电磁振动噪声频谱,确定了对电机电磁振动起主要作用的低阶电磁力的频率。最后利用遗传-蚁群算法,研究了通过优化电机的定子齿槽参数有效削弱具有上述频率的低阶电磁力,从而有效抑制电机的电磁振动。结果显示,利用所提方法确定的定子齿槽参数能有效抑制电机的电磁振动,并且对电机的运行性能产生的影响较小。

关键词：永磁同步电动机电磁振动解析分析遗传-蚁群算法抑制措施

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高寒草地四种植物叶片化学计量学特征及其对坡度的响应

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草地学报 2024年第1期32卷 121-129页

作者：鄯仁欠姐姚步青李永晓马丽萍雷雨田马忠武王芳萍郭玉朋周华坤青海大学生态环境工程学院青海西宁810016 中国科学院西北高原生物研究所青海省寒区恢复学重点实验室青海西宁810008 青海省交通规划设计研究院有限公司青海西宁810002 青海民族大学生态环境与资源学院青海西宁810000

本研究以高寒草甸和高寒灌丛共有物种黑褐苔草(Carex atrofusca Schkuhr Riedgr.)、黄花棘豆(Oxytropis ochrocephala Bunge.)、冷地早熟禾(Poa crymophila Keng.)、乳白香青(Anaphalis lactea Maxim.)为研究对象,比较分析四种植物叶片碳(Carbon, C)、氮(Nitrogen, N)、磷(Phosphorus, P)含量差异及其随坡度变化的变化趋势。结果表明:高寒草甸植物叶片C,N含量、C/N比值种间差异显著,高寒灌丛植物叶片N,P含量,C/N,C/P,N/P比值种间差异显著;高寒灌丛乳白香青叶片C/N,C/P比值和黄花棘豆叶片C/P,N/P比值显著高于高寒草甸;随着坡度增大,两种草地类型所有植物叶片C含量和N/P比值均无显著变化趋势;高寒草甸黑褐苔草和黄花棘豆叶片N含量显著减少,C/N比值显著增大;高寒灌丛乳白香青叶片P含量显著减少,C/P比值显著增大。两种草地类型植物叶片化学计量特征对坡度的响应差异说明了植物适应环境策略的多样化。

关键词：高寒草地坡度植物化学计量学环境适应策略

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Three-stage niobium mineralization at Bayan Obo, China

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National Science Review 2024年第4期11卷 102-110页

作者： Yan Yu Yang li Yu liu xiao-xiao ling li-Guang Wu li Yang Lan Yang Bo Yang yong-Gang Zhao Xian-Hua li State Key Laboratory of lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences College of Earth and Planetary Science University of Chinese Academy of Sciences Ministry of Education Key Laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space SciencesPeking University Mining Research Institute Baotou Iron and Steel(Group) Co.LTD State Key Laboratory of Baiyunobo Rare Earth Resource Research and Comprehensive Utilization

The Chinese Bayan Obo deposit is a world-class rare earth element(REE) deposit with considerable niobium(Nb) and iron(Fe) resources. A complete genetic understanding on all metals is fundamental for establishing genetic models at Bayan Obo. With extensive research being focused on REE enrichment, the timing and controls of Nb enrichment remain unresolved at Bayan Obo, which is mainly due to the challenges in dating, i.e. multistage thermal events, fine-grained minerals with complex textures and the rare occurrence of uranium-enriched minerals with mature dating methods. Based on robust geological and petrographic frameworks, here we conducted ion probe uranium-lead(U-Pb) dating of ferrocolumbite to unravel the timing, hence the genesis of Nb mineralization. Three types of hydrothermal ferrocolumbites—key Nb-bearing minerals—are identified based on their textures and mineral assemblages. They yield U-Pb ages of 1312 ± 47 Ma(n = 99), 438 ± 7 Ma(n = 93), and 268 ± 5 Ma(n = 19), respectively. In line with deposit geology, we tentatively link the first, second and third stage Nb mineralization to Mesoproterozoic carbonatite magmatism, ubiquitous early Paleozoic hydrothermal activity, and Permian granitic magmatism, respectively. While quantifying the contribution of metal endowment from each stage requires further investigation, our new dates highlight that multi-stage mineralization is critical for Nb enrichment at Bayan Obo, which may also have implications for the enrichment mechanism of Nb in REE deposits in general.

关键词： niobium mineralization U-Pb dating ferrocolumbite Bayan Obo

Effect of oxide inclusions on MnS precipitates and tensile mechanical property of high-strength low-alloy steel

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Journal of Iron and Steel Research(International) 2024年第5期31卷 1210-1220页

作者： xiao-yong Gao Hong Wei li-feng Zhang School of Mechanical Engineering Yanshan UniversityQinhuangdao066004HebeiChina School of Materials Science and Engineering Yanshan UniversityQinhuangdao066004HebeiChina School of Mechanical and Materials Engineering North China University of TechnologyBeijing100144China

The key role of oxide inclusions on the microstructure and mechanical property of a high-strength low-alloy steel was investigated.The field emission scanning electron microscope equipped with energy-dispersive spectrometry was used to characterize MnS precipitates.Oxide inclusions play an important role in the shape control of MnS precipitates.More oxides fovored to decrease the size and the aspect ratio of MnS precipitates.With less oxide inclusions in the steel,approximately over 16.7%MnS precipitates were with aspect ratio a>5 and pure MnS precipitates accounted for 75.9%in number.However,with more oxide inclusions in the steel,only 7.4%MnS precipitates were with a>5 and pure MnS precipitates accounted for 60.1%in number.Refinement of MnS by oxide inclusions improved the strength and inhibited the anisotropy.More oxide inclusions in the steel increased the yield strength and tensile strength of the steel in both longitudinal and transverse directions,and lowered the anisotropy of the mechanical property.

关键词： High-strength low-alloy steel MnS Oxide inclusion Mechanical property Anisotropy

Energy consumption optimization for edge computing-supported cellular networks based on optimal transport theory

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Science China(Information Sciences) 2024年第2期67卷 201-218页

作者： Xiangyu LV xiaohu GE Yi ZHONG Qiang li yong xiao School of Electronic Information and Communications Huazhong University of Science and Technology

With advancements in mobile communication technologies, there have been multiple user device(UD) connections to cellular networks. Because of changes in the spatial distribution of UDs and application requirements, the traditional offloading mechanism based on the nearest distance will result in heavy loads for some base stations(BSs). Because there is a high-order relationship between the energy consumption of the BS processing tasks and the number of computing tasks, the traditional offloading mechanism will result in high energy consumption, and UD’s offloading decision must be dynamically adjusted. The offloading decision of UDs is optimized based on detailed information about various parameters associated with a network from the standpoint of distribution. This information includes details regarding the spatial distribution of UDs,application requirements, and the offloading period of computing tasks. Based on optimal transport theory,an energy consumption optimization algorithm is suggested to lower the total amount of energy consumed by the offloading process of UDs’ computing tasks by reasonably planning the offloading BSs of the UDs in the networks. The simulation results show that the proposed offloading mechanism based on energy consumption optimization reduces the total energy consumption of the offloading process by 28.09% when compared to the traditional offloading mechanism, and the traffic managed by each BS is balanced.

关键词： optimal transport theory edge computing energy consumption reduction dynamic voltage frequency scaling

Preoperative neutrophil-to-lymphocyte ratio predicts symptomatic anastomotic leakage in elderly colon cancer patients: Multicenter propensity score-matched analysis

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World Journal of Gastrointestinal Surgery 2024年第2期16卷 438-450页

作者： Chao-Yang Wang xiao-Long li xiao-Long Ma Xiong-Fei Yang yong-yong liu yong-Jiang Yu Department of Clinical Medicine The First Clinical Medical College of Lanzhou UniversityLanzhou 730000Gansu ProvinceChina Department of Gastrointestinal Surgery First Hospital of Lanzhou UniversityLanzhou 730000Gansu ProvinceChina Department of Clinical Medicine Gansu University of Chinese MedicineLanzhou 730000Gansu ProvinceChina Department of Anorectology Gansu Provincial People’s HospitalLanzhou 730000Gansu ProvinceChina Department of General Surgery The Second Hospital Affiliated to Lanzhou UniversityLanzhou 730000Gansu ProvinceChina

BACKGROUND The neutrophil-to-lymphocyte ratio(NLR),a composite inflammatory biomarker,is associated with the prognosis in patients with colorectal tumors.However,whether the NLR can be used as a predictor of symptomatic postoperative ana-stomotic leakage(AL)in elderly patients with colon cancer is unclear.AIM To assess the role of the NLR in predicting the occurrence of symptomatic AL after surgery in elderly patients with colon cancer.METHODS Data from elderly colon cancer patients who underwent elective radical colectomy with anastomosis at three centers between 2018 and 2022 were retrospectively analyzed.Receiver operating characteristic curve analysis was performed to determine the best predictive cutoff value for the NLR.Twenty-two covariates were matched using a 1:1 propensity score matching method,and univariate and multivariate logistic regression analyses were used to determine risk factors for the development of postoperative AL.RESULTS Of the 577 patients included,36(6.2%)had symptomatic AL.The optimal cutoff value of the NLR for predicting AL was 2.66.After propensity score matching,the incidence of AL was significantly greater in the≥2.66 NLR subgroup than in the<2.66 NLR subgroup(11.5%vs 2.5%;P=0.012).Univariate logistic regression analysis revealed statistically significant correlations between blood transfusion intraoperatively and within 2 d postoper-atively,preoperative albumin concentration,preoperative prognostic nutritional index,and preoperative NLR and AL occurrence(P<0.05);multivariate logistic regression analysis revealed that an NLR≥2.66[odds ratio(OR)=5.51;95%confidence interval(CI):1.50-20.26;P=0.010]and blood transfusion intraoperatively and within 2 d postoperatively(OR=2.52;95%CI:0.88-7.25;P=0.049)were risk factors for the occurrence of symptomatic AL.CONCLUSION A preoperative NLR≥2.66 and blood transfusion intraoperatively and within 2 d postoperatively are associated with a higher incidence of postoperative symptomatic AL in elderly patients with colon cancer.The preoperative NLR

关键词： Colon cancer Anastomotic leak Neutrophil-to-lymphocyte ratio Propensity score-matched

Impact wear properties of dissimilar joints between bainitic frogs and pearlite rails

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Journal of Iron and Steel Research(International) 2024年第1期31卷 275-287页

作者： Pin-yong Zeng Chun-guang Zuo xiao-yu Zhang Wei li Tribology Research Institute Southwest Jiaotong UniversityChengdu610031SichuanChina

The impact wear behavior and damage mechanism of dissimilar welded joints between U26Mn frog and U75 V rail before and after normalizing treatment were studied by cyclic impact tests.The experiment indicated that the impact wear volume of the joints increased with the increasing number of impact cycles.The main wear mechanisms include pitting wear,mild fatigue wear,delamination wear,and fatigue wear,and plastic deformation was the primary impact wear mechanism.Among them,fatigue wear had the greatest influence on wear volume,while other wear mechanisms had limited effect.The impact wear resistance of the base material was better than that of the heat-affected zone.Normalizing treatment was beneficial to improving the impact wear resistance of welded joints owing to its effect to promote pearlite recovery,grain refinement,and uniform distribution of grains.The martensite generated in the rail welded joints aggravated the impact wear damage to the materials,which should be avoided.

关键词： Dissimilar welded joint Impact wear Bainitic steel Damage mechanism Wear rate

Systematic bibliometric analysis of research hotspots and trends on the application of premium IOLs in the past 2 decades

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International Journal of Ophthalmology(English edition) 2024年第4期17卷 736-747页

作者： liang-Pin li li-Yun Yuan De-Shen Mao Xia Hua xiao-yong Yuan Clinical College of Ophthalmology Tianjin Medical UniversityTianjin 300020China Tianjin Key Laboratory of Ophthalmology and Visual Science Tianjin Eye InstituteTianjin Eye HospitalTianjin 300020China School of Medicine Nankai UniversityTianjin 300071China Anhui Medical University Hefei 230032Anhui ProvinceChina Tianjin Aier Eye Hospital Tianjin UniversityTianjin 300190China

AIM:To analysis of research hotspots and trends on the application of premium intraocular lens(PIOLs)in the past 2 decades.METHODS:The literature search was performed on the Web of Science and included PIOLs studies published between January 2000 and December 2022.The retrieved literature was collated and analyzed by R-tool’s Bibliometrix package,CitNetExplorer,CiteSpace and other software.RESULTS:A total of 1801 articles about PIOLs were obtained,most of which were published in Spain and the United States.The organization that published the most articles was the University of Valencia in Spain.Alió JL,and Montés-Micó R,from Spain were the most influential authors in this field.The Journal of Cataract and Refractive Surgery and Journal of Refractive Surgery were the core journals for this field;the top 10 cited articles mainly focus on postoperative satisfaction with multifocal intraocular lens(IOLs)and postoperative results of toric IOLs.Through the keyword analysis,we found that trifocal IOLs,astigmatism and extended depth of focus(EDoF)IOLs are the most discussed topics at present,and the importance of astigmatism and the clinical application of the new generation of PIOLs are the emerging research trends.CONCLUSION:Bibliometric analysis can effectively help to identify multilevel concerns in PIOLs research and the prevailing research trends in the realm of PIOLs encompass the adoption of EDoF IOLs,trifocal IOLs,and their respective Toric models.

关键词： premium intraocular lens bibliometric H-index cataract surgery global trends

Chemical derivatization strategies for enhancing the HPLC analytical performance of natural active triterpenoids

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Journal of Pharmaceutical Analysis 2024年第3期14卷 295-307页

作者： xiao-Feng Huang Ying Xue li yong Tian-Tian Wang Pei Luo lin-Sen Qing Chengdu Institute of Biology Chinese Academy of SciencesChengdu610041China State Key Laboratory for Quality Research in Chinese Medicines Macao University of Science and TechnologyMacaoChina Sichuan Center for Disease Control and Prevention Chengdu610041China University of Chinese Academy of Sciences Beijing100049China

riterpenoids widely exist in nature,displaying a variety of pharmacological activities.Determining triterpenoids in different matrices,especially in biological samples holds great significance.High-performance liquid chromatography(HPLC)has become the predominant method for triterpenoids analysis due to its exceptional analytical performance.However,due to the structural similarities among botanical samples,achieving effective separation of each triterpenoid proves challenging,necessitating significant improvements in analytical methods.Additionally,triterpenoids are characterized by a lack of ultraviolet(UV)absorption groups and chromophores,along with low ionization efficiency in mass spectrometry.Consequently,routine HPLC analysis suffers from poor sensitivity.Chemical derivatization emerges as an indispensable technique in HPLC analysis to enhance its performance.Considering the structural characteristics of triterpenoids,various derivatization reagents such as acid chlorides,rhodamines,isocyanates,sulfonic esters,and amines have been employed for the derivatization analysis of triterpenoids.This review comprehensively summarized the research progress made in derivatization strategies for HPLC detection of triterpenoids.Moreover,the limitations and challenges encountered in previous studies are discussed,and future research directions are proposed to develop more effective derivatization methods.

关键词： Triterpenoid HPLC Derivatization Quantification