检索结果-南通市图书馆

Bonding and Fracture Characteristics at α_2/γ Interface in TiAl Alloy with B Addition

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 1999年第1期15卷 43-47页

作者： Senying LIU Dongliang ZHAO rongze hu and chongyu wang(Central Iron and Steel Research Institute, Beijing 100081, China)Ping LUO(National Research Center for CRM, Beijing 100013, China) Central Iron and Steel Research Institute Beijing 100081 China National Research Center for CRM Beijing 100013 China

The bonding characteristics of (0001)α2||(111)γ interface in two-phase TiAl alloy have beeninvestigated with the recursion method. The results of bond order integral and interaction energybetween atoms are presented. The effects of B on atoms bonding both in constituent phase andat the α2/γ interface have been studied. The correlation between the mechanical propertiesof the alloy and the bonding at the interface has been discussed. The results suggest that Bsegregation to the interface benefits the ductility. This is supported by the related experiment.

关键词： TiAl Bonding and Fracture Characteristics at Interface in TiAl Alloy with B Addition

Electronic Structure Effect on Model Cluster for L1_2 Structure of Al_3Ti Intermetallic Compound with an Addition of Alloying Elements Fe, Ni and Cu

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 1995年第5期11卷 369-372页

作者： Senying LIU rongze hu Dongliang ZHAO and chongyu wang(Central Iron and Steel Research Institute, Beijing, 100081, China)(To whom correspondence should be addressed)Ping LUO(National Research Cent or Certified Materials, Beijing, 100013, China)Zhongjie P Central Iron and Steel Research Inst Beijing China

By use of self-consistent field Xα scattered-wave (SCF-Xα-SW) method, the electronic structure was calculated for four models of Ti4Al14X (X=Al, Fe, Ni and Cu) clusters. The Ti4Al14X cluster was developed based on L12 Al3Ti-base intermetallic compound. The results are presented using the density of states (DOS) and one-electron properties, such as relative binding tendency between the atom and the model cluster, and hybrid bonding tendency between the alloying element and the host atoms. By comparing the four models of Ti4Al14X cluster, the effect of the Fe, Ni or Cu atom on the physical properties of Al3Ti-based L12 intermetallic compounds is analyzed. The results indicate that the addition of the Fe, Ni or Cu atom intensifies the relative binding tendency between Ti atom and Ti4Al14X cluster. It was found that the Fermi level (EF) lies in a maximum in the DOS for Ti4Al14Al cluster; on the contrary, the EF comes near a minimum tn the DOS for Ti4Al14X (X=Fe, Ni and Cu) cluster. Thus the L12 crystal structure for binary Al3Ti alloy is unstable, and the addition of the Fe, Ni or Cu atom to Al3Ti is benefical to stabilize L12 crystal structure. The calculation also shows that the Fe, Ni or Cu atom strengthens the hybrid bonding tendency between the central atom and the host atoms for Ti4Al14X cluster and thereby may lead to the constriction of the lattice of Al3Ti-base intermetallic compounds.

关键词： Fe Electronic Structure Effect on Model Cluster for L12 Structure of Al3Ti Intermetallic Compound with an Addition of Alloying Elements Fe Al Ti Cu

Bonding Characteristics of the Intermetallic Compound Al_3Ti+Cr

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 1996年第3期12卷 180-184页

作者： Senying LIU rongze hu Dongliang ZHAO and chongyu wang (Central Iron and Steel Research Institute, Beijing 100081, China)Ping LUO (National Research Center for Certified Material, Beijing 100013, China)Zhongjie PU (Florida International University, Miami Central Iron and Steel Research Institute Beijing 100081 China National Research Center for Certified Material Beijing 100013 China Florida International University Miami FL 33199 United States

Based on our structural model and a tight-binding Hamiltonian the eIectronic structure has been calculated by use of a recursion method (RM) for two models of the tetragonal DO22 and the cubic Ll2 crystal structures in Al3Ti+Cr for contrast, from which bonding characteristics have been discussed. The results for the interaction energy (IE) show that Cr prefers to replacing Al site. Cr partly replacing Al can change the IE between the atoms and make the constriction of lattice constant c and the elongation of lattice constant a for the DO22 and thereby may induce the change of crystal structure from DO22 to L12. The results for bond order integral (BOI) and IE between the atoms also show that the strong (110) directional Cr-Ti bondings are ***, Al3Ti-base intermetallic compounds with addition of the Cr atom still remain brittle.

关键词： Ti II Al Bonding Characteristics of the Intermetallic Compound Al3Ti+Cr Res

rs-fMRI结合图论分析对癫痫共病抑郁的脑功能网络研究

在线全文

学校读者我要写书评

暂无评论

磁共振成像 2024年第6期15卷 24-30页

作者：潘红刘超荣胡爱丽黄彪苏琦艳周夏怡胡崇宇湖南省人民医院(湖南师范大学附属第一医院)神经内科长沙414000 邵阳市中心医院神经内科邵阳422000

目的采用静息态功能磁共振成像(resting-state functional magnetic resonance imaging,rs-fMRI)结合图论分析方法研究癫痫共病抑郁的脑功能网络拓扑结构。材料与方法对所纳入55例癫痫患者行rs-fMRI检查和17项版汉密尔顿抑郁量表(Hamilt... 详细信息

目的采用静息态功能磁共振成像(resting-state functional magnetic resonance imaging,rs-fMRI)结合图论分析方法研究癫痫共病抑郁的脑功能网络拓扑结构。材料与方法对所纳入55例癫痫患者行rs-fMRI检查和17项版汉密尔顿抑郁量表(Hamilton Depression Rating Scale,HAMD)评估,根据HAMD评分将其分成抑郁组和非抑郁组,最终纳入抑郁组30例(ED组),非抑郁组25例(E组)。基于rs-fMRI结合图论的脑网络分析方法,构建脑功能连接网络,计算脑网络拓扑结构全局及节点指标,并进行两组间比较,分析ED组与E组脑网络拓扑属性是否存在异常及异常指标与HAMD评分是否存在相关性。结果ED组患者的聚类系数(clustering efficiency,Cp)、标准化特征路径长度(lambda,λ)下降(P<0.05)。在节点水平,中心性下降的脑区包括左侧楔叶、左侧枕上回;中心性升高的脑区位于右侧额中回眶部,差异均有统计学意义(P<0.05,FDR校正)。全局属性Cp(r=−0.349,P=0.012),左侧枕上回节点聚类系数(nodal clusteering coefficient,NCp)(r=−0.382,P=0.006)、左侧楔叶NCp(r=−0.477,P<0.001)、左侧枕上回节点局部效率(nodal local efficiency,NLe)(r=−0.351,P=0.011)与HAMD评分呈负相关,右额中回眶部NLe(r=0.409,P=0.003)与HAMD评分呈正相关。结论癫痫共病抑郁是一种脑网络疾病,其脑功能网络的部分全局及节点指标存在异常改变,为更好地了解癫痫共病抑郁的发生发展提供了影像学依据。

关键词：癫痫抑郁静息态功能磁共振成像磁共振成像脑功能网络图论分析

Evaluating Functions of Reservoirs'Storage Capacities and Locations on Daily Peak Attenuation for Ganjiang River Basin Using Xinanjiang Model

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2016年第6期26卷 789-802页

作者： DU Jinkang ZHENG Dapeng XU Youpeng hu Shunfu XU chongyu School of Geographic and Oceanographic Sciences Nanjing UniversityNanjing 210093China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing 210023China Anhui Electric Power Design Institute of China Energy and Electricity Construction Group Hefei 230601China Department of Geography Southern Illinois University EdwardsvilleEdwardsville IL 62026USA State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China Department of Geosciences University of OsloN-0316 Oslo 1047 BlindernNorway

Flooding is the most prevalent and costly natural disaster in the world and building reservoirs is one of the major structural measures for flood control and management. In this paper, a framework was proposed to evaluate functions of reservoirs′ locations and magnitudes on daily peak flow attenuation for a large basin of China, namely Ganjiang River Basin. In this study, the Xinanjiang model was adopted to simulate inflows of the reservoirs and flood hydrographs of all sub-catchments of the basin, and simple reservoir operation rules were established for calculating outflows of the reservoirs. Four reservoirs scenarios were established to analyze reservoirs′ locations on daily peak flow attenuation. The results showed that: 1) reservoirs attenuated the peak discharges for all simulated floods, when the flood storage capacities increase as new reservoirs were built, the peak discharge attenuation by reservoirs showed an increasing tendency both in absolute and relative measures; 2) reservoirs attenuated more peak discharge relatively for small floods than for large ones; 3) reservoirs reduced the peak discharge more efficiently for the floods with single peak or multi peaks with main peak occurred first; and 4) effect of upstream reservoirs on peak attenuation decreased from upper reaches to lower reaches; upstream and midstream reservoirs played important roles in decreasing peak discharge both at middle and lower reaches, and downstream reservoirs had less effect on large peak discharge attenuation at outlet of the basin. The proposed framework of evaluating functions of multiple reservoirs′ storage capacities and locations on peak attenuation is valuable for flood control planning and management at basin scale.

关键词： reservoir peak flow Xinanjiang model reservoir operation Ganjiang River Basin

在线全文

学校读者我要写书评

暂无评论

黄河板块旅游公路设计要点分析与应用研究

城市道桥与防洪 2024年第4期 34-38,I0003页

作者：魏贤鹏胡中梅姜荣泽孔庆伟上海市政交通设计研究院有限公司上海市200030

黄河作为中华文明发源地,在我国经济社会发展和生态安全方面具有十分重要的地位.黄河板块旅游公路的建设对实现黄河流域高质量发展、开发旅游资源、挖掘民族文化、丰富国民精神需求均具有积极意义.针对黄河板块旅游公路的特殊性,从选线... 详细信息

黄河作为中华文明发源地,在我国经济社会发展和生态安全方面具有十分重要的地位.黄河板块旅游公路的建设对实现黄河流域高质量发展、开发旅游资源、挖掘民族文化、丰富国民精神需求均具有积极意义.针对黄河板块旅游公路的特殊性,从选线、慢行系统、沿河景观、沿河路基等方面分析设计要点,并结合实际工程案例分析黄河板块旅游公路设计过程和思路;同时,针对黄河旅游公路建设中重难点如沿河路基设计、高路堤稳定性等问题进行重点分析计算.

关键词：黄河流域旅游公路沿河路基高路堤稳定性

在线全文

学校读者我要写书评

暂无评论

脑小血管病脑白质高信号危险因素相关性分析

湖南师范大学学报（医学版） 2024年第1期21卷 66-70,80页

作者：苏琦艳黄彪胡爱丽潘红胡崇宇湖南师范大学附属第一医院长沙410005 邵阳市中心医院邵阳422000

目的:评估脑小血管病(CSVD)中脑白质高信号(WMHs)的危险因素,并进一步建立早期预测模型。方法:选取湖南省人民医院住院的233例患者进行回顾性分析,根据头部磁共振平扫T2序列辨别WMHs,分为WMHs的观察组187例,无WMHs的对照组46例,随机选取... 详细信息

目的:评估脑小血管病(CSVD)中脑白质高信号(WMHs)的危险因素,并进一步建立早期预测模型。方法:选取湖南省人民医院住院的233例患者进行回顾性分析,根据头部磁共振平扫T2序列辨别WMHs,分为WMHs的观察组187例,无WMHs的对照组46例,随机选取170例作为训练集,63例作为验证集。训练集中两组患者的一般资料、相关生化指标进行组间比较,对差异因素进行多因素Logistic回归分析,对独立危险因素进行单项及多项联合绘制受试者工作特征(ROC)曲线,同时构建列线图,建立预测模型,并评价模型预测效能。结果:训练集两组患者间年龄、高血压、冠心病、单核细胞计数、血尿素氮(BUN)、血清肌酐(SCr)、肾小球滤过率(eGFR)具有统计学差异,这7项指标进行多因素回归分析显示高血压、SCr水平是WMHs的独立危险因素。绘制高血压、SCr及2项指标联合预测WMHs的ROC曲线,曲线下面积分别为0.655、0.680、0.762。通过构建高血压、SCr的列线图,绘制预测模型并与单独的高血压、SCr诊断验证集发生WMHs的ROC曲线进行效能评价,其曲线面积分别为0.763、0.708、0.649。结论:高血压、SCr是WMHs的独立危险因素,且对WMHs具有一定的预测价值,联合高血压与SCr预测WMHs风险要优于单一指标,对WMHs的早期诊断具有一定的指导价值。

关键词：脑白质高信号危险因素血清肌酐单核细胞

农业种植智能体(Agri-agent)的构建与应用展望

在线全文

学校读者我要写书评

暂无评论

农业展望 2024年第6期20卷 92-106页

作者：任荣荣胡崇宇吴国龙北大荒信息有限公司黑龙江哈尔滨150001

在农业领域中,由于生产环境、生产能力和生产目标多种多样,如何有效管理这种多样性成为农业智能化和现代化的关键。种植智能体以其系统性、自治性和具身性等特征,可成为农业实现系统化、智能化和现代化的可行方案。本研究对农业中智能... 详细信息

在农业领域中,由于生产环境、生产能力和生产目标多种多样,如何有效管理这种多样性成为农业智能化和现代化的关键。种植智能体以其系统性、自治性和具身性等特征,可成为农业实现系统化、智能化和现代化的可行方案。本研究对农业中智能体技术的发展进行分析,提出了种植智能体的概念框架,有助于更好地定位智慧农业的应用方向。本研究围绕智能体的内涵形态、技术架构和业态趋向3个方面展开研究,初步建立了智慧农业种植智能体的系统框架。该框架包括种植智能体的定义、特性、架构、关键技术,并对未来发展方向进行初步探讨。该方法旨在为智慧农业种植智能体的进一步研究奠定基础,提出切实可行的解决方案,最终建立信息化、智能化的智慧农业种植体系。在数字技术与农业深度融合的背景下,种植智能体框架及应用解决方案在保障农产品供给、提升农业抗风险能力方面将发挥重要的作用,为农业的智能化、可持续发展注入新的活力。

关键词：智慧农业多智能体系统农业种植智能体粮食安全农业科技创新

中国新型冠状病毒疫苗犹豫影响因素Meta分析

在线全文

学校读者我要写书评

暂无评论

中国预防医学杂志 2024年第6期25卷 757-762页

作者：余娜牛雨田吴娟柏晓玲郭世鸿胡庆杨容泽肖婷贵州中医药大学第二附属医院预防保健科贵州贵阳550001 贵阳康养职业大学护理学院贵州中医药大学护理学院贵州护理职业技术学院护理系贵州中医药大学第二附属医院急诊科贵州贵阳550001

目的了解新型冠状病毒疫苗(新冠疫苗)犹豫的影响因素,为降低新冠疫苗接种犹豫提供参考依据。方法系统检索2020年1月1日—2022年7月31日中国知网(CNKI)、万方(Wanfang Database)、维普(VIP)、中国生物医学文献数据库(SinoMed)、PubMed、E... 详细信息

目的了解新型冠状病毒疫苗(新冠疫苗)犹豫的影响因素,为降低新冠疫苗接种犹豫提供参考依据。方法系统检索2020年1月1日—2022年7月31日中国知网(CNKI)、万方(Wanfang Database)、维普(VIP)、中国生物医学文献数据库(SinoMed)、PubMed、Embase、Web of Science、MEDLINE以及Cochrane Library数据库中涉及新冠疫苗犹豫及其影响因素的相关文献,运用Stata 15软件进行Meta分析。结果本研究共纳入19篇相关文献,研究对象总数为70318人,新冠疫苗犹豫的合并效应值为32%(95%CI:0.25~0.38)。疫苗接种影响因素的Meta分析结果显示,女性(OR=1.35,95%CI:1.23~1.49)、本科及以上学历(OR=1.75,95%CI:1.31~2.33)、存在基础疾病(OR=1.52,95%CI:1.36~1.68)、认为身体健康不需要接种新冠疫苗(OR=2.05,95%CI:1.66~2.52)、认为国内风险不高不需要接种疫苗(OR=2.12,95%CI:1.47~3.05)、认为疫苗存在风险(OR=1.57,95%CI:1.39~1.76)、担心疫苗有不良反应(OR=2.35,95%CI:1.83~3.01)、受家人/朋友/同事疫苗犹豫的影响(OR=1.55,95%CI:1.34~2.81)是疫苗犹豫的促进因素(OR>1.00,P<0.05);而对疫苗的信任(OR=0.55,95%CI:0.43~0.70)、认为疫苗有效(OR=0.44,95%CI:0.38~0.52)、自认为有高感染新冠病毒的风险(OR=0.41,95%CI:0.34~0.49)是疫苗犹豫的阻碍因素(OR<1.00,P<0.05)。结论民众对接种新冠疫苗存在不同程度的犹豫,建议加强疫苗安全性、有效性、接种后不良反应及接种注意事项等相关知识的健康科普宣教,提高民众对疫苗的信任,以及对自身感染风险的判断,从而降低疫苗犹豫程度。

关键词：新型冠状病毒疫苗疫苗犹豫 Meta分析