92 research outputs found

    Research of fuzzy time series model based on fuzzy entropy and fuzzy clustering

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    时间序列预测是通过对有限个历史观测样本进行分析来建立模型,并利用模型来解释数据之间的统计规律,以期达到控制和预报目的的一门学科,在众多领域中都有非常广泛的应用。对于时间序列的建模和预测,目前已经有了许多成熟的技术和方法,但传统时间序列预测方法往往依赖大量的历史数据,而在实际问题中由于不确定性的广泛存在导致历史数据往往是不完整的、不准确的和含糊的,因而限制了传统预测模型的应用。为了解决这些问题,Song和Chissom提出了模糊时间序列的概念,其主要是在传统时间序列预测的基础上引入了模糊理论,通过建立相应的模糊逻辑关系进行预测。由于模糊时间序列在处理数据的不确定性和模糊性方面上所显示的优势,关于...Time series forecasting is modeled by limited historical observations sample, it is a technology of using the model to explain the statistical regularity of data in order to achieve the purpose of control and forecast and having a wide range of applications in many fields. For time series modeling and forecasting, there are many mature technologies and methods. The traditional time series predicti...学位:理学硕士院系专业:数学科学学院_概率论与数理统计学号:1902010115250

    Preparation of Alumina Ceramic Microfiltration Membrane and its Application in Soy Sauce Clarification

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    无机陶瓷膜是一种由Al2O3、TiO2、ZrO2和SiO2等无机材料制备的多孔分离膜。由于其化学性能稳定、过滤精度可控(微滤、超滤、纳滤)、能耗小、环保等优点广泛应用于食品、生物、化工等各种领域。本文研究了氧化铝支撑体和微滤膜的制备,并初步探讨氧化铝陶瓷膜在酱油澄清中的应用。 实验中选用平均粒径37μm的α-Al2O3为原料,PVA为开孔剂和粘结剂,高岭土为烧结助剂,采用挤出成型法制备氧化铝陶瓷膜支撑体。制备出孔径10.3μm的支撑体,孔隙率为48.2%,纯水通量为4900L/m2•h,抗弯强度为38MPa。实验表明:当PVA含量增加,孔径和孔隙率会随之增大,纯水通量就会增大,而...Inorganic ceramic membrane is a kind of porous membranes which is made from Al2O3, TiO2, ZrO2 or SiO2. It has been widely used in food, biological, chemical and other fields because of its advantages such as stable performance, low energy consumption, environmentally friendly and so on. In this paper, we focused on the preparation of alumina support and membranes, also the applications in soy sau...学位:理学硕士院系专业:材料学院材料科学与工程系_高分子化学与物理学号:2072008115057

    A Preliminary Study of Wuhu Iron Painting ——The Inheritance of Chinese Traditional Culture Reflected in the Ups and Downs of Iron Painting Art

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    诞生于清康熙年间的芜湖铁画已历数百年风雨,其间几度“人亡”、“业息”、“失其真”。但在中华民族和地方科学技术文化的涵养以及工艺美术文化的滋润下,仍然具有极其顽强的生命力,人兴业旺,“技不绝”,成为中华民族科技和工艺园苑里的一朵奇葩,我们文明古国的瑰宝。 本文从探讨铁画的起源出发,揭示出劳动人民的共同智慧才是我国悠久文明的创造者这个道理。并通过对芜湖地理、经济、政治、艺术环境的综合分析,探寻铁画在这里成名的原因。最后试图通过这门传统工艺古与今、浮与沉的对比,探究我国传统文化的保护和传承之路。 全文分为五部分: 绪论,介绍选题缘起、相关学术史回顾以及本文研究方法。 第一章,试探铁画创始的踪...Wuhu iron painting which appeared in Qing Emperor has passed hundreds of years. However,because of Chinese local science ,technology, culture, arts and crafts, it still has a very strong vitality now. It just likes a beautiful flower blooming in the park of the Chinese national Scientific, Technical and Technological Park, and also likes a treasure in our ancient civilization. This dissertat...学位:历史学硕士院系专业:人文学院历史学系_经济史学号:1032006115011

    集聚视角下的中国城市化与区域经济增长

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    世界主要国家的发展历程表明,一国的城市化与经济增长密切关联。一般认为,城市化对经济增长通常表现出正向的驱动作用。但相关研究中,更多是从传统的视角强调城市化过程中结构转变的影响,而新近理论研究则表明经济活动的集聚也有助于经济增长。本文基于对已有研究的讨论,认为在经济全球化和一体化的背景下,有效率的城市化应该是结构转变和集聚的统一,考察城市化对经济增长的促进作用应该综合考虑集聚的影响。为此,本文区分了两种类型(宽度和深度)的城市化涵义,并采用动态面板回归模型的gMM估计法,从集聚和二元结构转变的综合视角探讨了中国各区域城市化对经济增长的推动作用及其差异,数据分析发现考虑集聚影响的城市化更能解释中国各区域城市化对经济增长的促进作用。同时,集聚还能进一步释放城市化的推动能力,延迟其推动作用“拐点“的出现。国家自然科学基金项目“二元经济背景下的增长与发展”(71273216/G0103); 福建省社科重大项目“二元结构下的城市化与经济增长”(2011Z012)的资

    Al_4团簇在NaCl(001)表面的结构和磁性

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    利用第一次性原理计算Al4团簇的重心吸附在nACl表面上两种桥位,两种空位,在nA原子顶位及Cl原子顶位的结构、平均每个Al原子的吸附能、最低的Al原子和nACl(001)表面原子之间的距离和磁矩。结果表明,Al4团簇的重心吸附在nACl表面上nA的顶位是最稳定的结构,吸附能最大,总能最大,最低的Al原子和nACl(001)表面原子之间的距离最小,但团簇的磁矩为0μb,其他位置Al4团簇则保留其在自由空间的磁矩

    虾青素对大鼠乙酸性胃溃疡的治疗作用

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    由多因素诱发的失控性胃酸分泌及胃防御功能损害而引起的胃溃疡是严重的全球性问题。近年来,氧自由基在胃黏膜损伤中的作用日益受到重视。许多研究表明,氧自由基所致的细胞损害是很多病

    正交实验法优选管式氧化铝陶瓷膜过渡层配方

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    采用固态粒子烧结法制备氧化铝管式陶瓷膜中的过渡层,以正交实验法系统研究过渡层配方的三种原料:三氧化二铝(Al2O3),聚乙烯醇(PVA),烧结助剂二氧化锆(ZrO2)各自质量分数以及涂膜次数对氧化铝陶瓷膜过渡层料液通量的影响。最终得出最佳工艺配方组合:ω(Al2O3)=23%,ω(ZrO2)=12%,ω(PVA)=4%,涂膜2次。并结合压汞法得出的孔径分布图和孔隙率推论:膜层孔径分布越窄,孔隙率越大,则膜通量越大

    柴郁地仙方对围绝经期抑郁症模型大鼠行为学及海马BDNF、TrkB蛋白表达的影响

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    目的观察柴郁地仙方对围绝经期抑郁症(perimenopausal depressive disorder, PDD)模型大鼠行为学及海马脑源性神经营养因子(brain derived neurotrophic factor, BDNF)、酪氨酸激酶B受体(tropomyosin receptor kinase B, TrkB)蛋白表达的影响,探讨其抗围绝经期抑郁症的作用机制。方法 48只3~4月龄雌性SD大鼠随机分为假手术组、模型组、阳性对照组、柴郁地仙方低、中、高剂量组,共6组,每组8只。假手术组行假手术,其余组行卵巢去势术后孤养并予以28天慢性轻度不可预见性应激(chronic unpredictable mild stress, CUMS)建立围绝经期抑郁症模型。CUMS第1天起假手术组、模型组灌服生理盐水,阳性对照组灌服盐酸氟西汀合戊酸雌二醇,中药治疗组灌服柴郁地仙方低、中、高不同浓度的汤药,其浓度分别为:0.38、0.76、1.52 g/mL,每天1次。应激过程中观察大鼠行为学及体重变化,并通过Morris水迷宫实验评价大鼠空间学习和记忆能力,应用免疫印迹法检测大鼠海马BDNF、TrkB蛋白表达情况。结果与假手术组比较,模型组大鼠体重增长缓慢,旷场实验得分及糖水偏好率均明显降低(P0.05)。结论柴郁地仙方可改善PDD模型大鼠行为学、体重水平及水迷宫的空间学习和记忆能力,其作用机制可能是通过提高大鼠海马中BDNF、TrkB蛋白表达量发挥的。福建省计生委中医药科研基金资助项目(No.wzpw201307);;福建省自然科学基金计划项目(No.2017J01147

    Sediment-water Flux and Processes of Nutrients and Gaseous Nitrogen Release in a China River Reservoir

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    以九龙江北溪西陂电站库区为例,于2013年不同季节开展原状泥柱静态培养、气态氮水柱剖面观测和通量模拟实验,结合水和沉积物理化参数和微生物参数,研究河流库区沉积物-水界面营养盐及气态氮的释放过程和通量.结果表明,库区沉积物nH+4和PO3-4总体表现为释放行为[平均nH+4通量(480±675)Mg·(M2·d)-1,平均PO3-4通量(4.56±0.54)Mg·(M2·d)-1],而nO-3和nO-2表现为吸附行为.洪水季节带来大量的有机质沉积在库区,造成枯水期沉积物无机氮磷向上覆水体释放.湖泊区气态氮释放以n2为主(>98%),沉积物-水界面n2释放通量平均为(15.8±12.5)Mg·(M2·d)-1.水柱n2净增量有明显的空间差异和垂向分布规律,受沉积物-水界面生地化过程(反硝化和厌氧氨氧化作用)和流动水团的综合影响.下游站位存在较强的硝化作用,n2O相对富集,主要受水中氨氮占无机氮的比例控制.The key processes and fluxes of nutrients( N and P) and gaseous N( N2 and N2O) across the sediment-water interface in a river reservoir( Xipi) of the Jiulong River watershed in southeast China were studied.Intact core sediment incubation of nutrients exchange,in-situ observation and lab incubation of excess dissolved N2 and N2O( products of nitrification,denitrification and Anammox),and determination of physiochemical and microbe parameters were carried out in 2013 for three representative sites along the lacustrine zone of the reservoir.Results showed that ammonium and phosphate were generally released from sediment to overlying water [with averaged fluxes of N( 479.8 ± 675.4) mg·( m2·d)- 1and P( 4.56 ± 0.54) mg·( m2·d)- 1],while nitrate and nitrite diffused into the sediment.Flood events in the wet season could introduce a large amount of particulate organic matter that would be trapped by the dam reservoir,resulting in the high release fluxes of ammonium and phosphate observed in the following low-flow season.No clear spatial variation of sediment nutrient release was found in the lacustrine zone of the reservoir.Gaseous N release was dominated by excess dissolved N2( 98% of total),and the N2 flux from sediment was( 15.8 ± 12.5) mg·( m2·d)- 1.There was a longitudinal and vertical variation of excess dissolved N2,reflecting the combined results of denitrification and Anammox occurring in anoxic sediment and fluvial transport.Nitrification mainly occurred in the lower lacustrine zone,and the enrichment of N2 O was likely regulated by the ratio of ammonium to DIN in water.国家自然科学基金项目(41076042;41376082); 中央高校基本科研业务费专项(2012121053); 中国科学院城市环境与健康重点实验室(城市环境研究所)开放基金项目(KLUEH201008
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