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未知激励下的无迹卡尔曼滤波新方法
Get PDF无迹卡尔曼滤波(UKF)是一种识别非线性系统的有效方法,然而传统的UKF方法需要观测外部激励,这限制了UKF的应用范围。迄今为止,国内外对未知激励情况下的UKF方法的研究还非常少。该文在传统UKF的基础上,推导出在未知激励情况下的无迹卡尔曼滤波(UKF-UI)方法的递推公式,通过对观测误差的最小化,利用非线性方程求解,识别未知外部激励,进而识别非线性结构系统状态与结构未知参数。进一步采用融合部分观测的加速度响应及位移响应,消除识别结果的漂移问题。分别通过白噪声和未知地震作用下识别非线性迟滞模型的两个数值算例,考虑观测噪声对非线性系统进行识别,从而验证提出新方法的有效性。结果表明,该文所提出的UKF-UI方法,能够在部分观测结构系统响应的情况下,有效地识别非线性结构参数和未知激励。国家自然科学基金资助项目(51678509);;\n福建省自然科学基金项目(2016J01263);;\n中央高校基本科研业务费专项资金资助项目(20720160076);;\n住房和城乡建设部科技项目(2016-K4-046);;\n厦门市交通基础设施智能管养工程技术研究中心资助项目(TCIMI201815
机构改革背景下城乡规划学科发展转型探讨
Get PDF组建自然资源部是在加强生态文明建设的新时代要求下政府机构改革和职能转变的体现,其将对目前城乡规划的体系构建、治理手段、技术方法等产生深刻影响,作为应用型学科的城乡规划应与时俱进地适应此次机构改革的需求。本文回顾我国城乡规划学科过去的发展历程,剖析机构改革背后折射出的时代特征及其对城乡规划转型发展的新要求,探讨机构改革背景下城乡规划学科未来的发展趋势,认为城乡规划学科应从技能、核心、特色和应用四个层面进行转型发展,主动应对新时期规划工作的新要求,积极融入国家空间规划体系的改革进程当中
城市收缩的机理与应对
Get PDF城市为什么收缩?在我刚进入规划行业的时候,城市能否增长并不是规划需要回答的问题,因为几乎所有的城市都是扩张型增长,我们城市规划的方法都是围绕此类城市而设计的,规划要回答的无非是增长多少、增长快慢的问题。过去十几年,城市收缩开始在中国被越来越多的数据所观察到。城市增长开始分化——有些城市继续增长,而另一些城市则增长停滞甚至开始收缩。规划师越来越多地面对一个以前没有遇到的新问题,收缩的城市还能发展吗?如
P2B网贷平台中的信息不对称风险研究
Get PDF随着互联网技术的发展,最近两年我国P2B平台数量增长迅速,成为投资者的新宠。但是我国P2B平台同样存在较为严重的资金安全问题。P2B平台之所以会产生这种现象,主要是由于平台借贷双方存在..
膝骨性关节炎病人的砭石循经穴位按摩效果观察
Get PDF[目的]探讨砭石循经穴位按摩在膝骨性关节炎病人中的应用效果。[方法]将60例膝骨性关节炎病人随机分为对照组与观察组,每组各30例。对照组予口服盐酸氨基葡萄糖胶囊和电脑中频治疗,观察组在对照组的基础上予砭石循经穴位按摩每天1次,7 d为1个疗程,共干预2个疗程。于1个疗程和2个疗程之后,比较两组西安大略和麦克玛斯特大学骨关节炎指数(WOMAC)和视觉模拟评分法(VAS),于2个疗程后比较两组关节炎生活质量测量量表简化量表(AIMS2-SF)中文版修改的量表评分。[结果]干预后两组WOMAC、VAS和AIMS2-SF评分分别与同组干预前比较,差异均具有统计学意义(P<0. 05);干预后观察组WOMAC评分和VAS评分低于对照组(P<0. 05),AIMS2-SF评分高于对照组(P<0. 05)。[结论]砭石循经穴位按摩可以缓解膝骨性关节炎的疼痛症状,改善关节功能及生活质量
Development, validation, comparison, and implementation of a highly efficient and effective method using magnetic solid-phase extraction with hydrophilic-lipophilic-balanced materials for LC-MS/MS analysis of pesticides in seawater
Get PDFAbstract(#br)To achieve multi-pesticides residue analysis in seawater, hydrophilic-lipophilic-balanced magnetic particles were designed and fabricated by swelling polymerization of divinyl benzene (DVB) and N-vinyl pyrrolidone (NVP) on the surface of Fe 3 O 4 @SiO 2 magnetic particles. The ratio of DVB to NVP was adjusted to achieve a proper balance in hydrophilicity and lipophilicity. The obtained magnetic particles were systematically characterized by TEM, SEM, FT-IR and vibrating sample magnetization. Based on the optimized magnetic nanoparticles, a sensitive magnetic solid-phase extraction method was developed for the simultaneous pre-concentration and determination of 96-pesticide residues from large-volume seawater samples prior to being detected by liquid chromatography-tandem mass spectrometry. Recoveries of pesticides in spiked seawater samples (0.001, 0.01, 0.1, 1.0 μg L −1 ) ranged from 62% to 112% with RSDs less than 21%. The method limits of detection of 96 pesticides ranged from 0.13 to 0.42 ng L −1 , the method limits of quantification of 96 pesticides ranged from 1.0 to 10 ng L −1 . The method was successfully applied to pesticide residue analysis in water samples from Jiulong River Estuary of China, demonstrating the prospects of this technique as a potential method for the rapid determination of trace levels of multi-pesticide residues in seawater
Transcriptome analysis of Medicago lupulina seedlings leaves treated by high calcium provides insights into calcium oxalate formation
Get PDFAbstract(#br) Background and aim(#br)Calcium oxalate (CaOx) is a common biomineral found in the plant kingdom. Crystals of CaOx occur in different plant tissues, such as leaves and stems. However, little is known about the biosynthesis of CaOx in oxalate-accumulating plants. Moreover, the literature on genes related to CaOx formation under high-calcium environment is scarce. In the present study, the physiological parameters and the transcript profiles of Medicago lupulina leaves treated with 0.1 and 25 mM Ca 2+ were analyzed to study the genes involved in the biosynthesis of CaOx.(#br) Results(#br)We demonstrated that exposure to high external calcium concentration induced H 2 O 2 production, ascorbic acid degradation, and CaOx accumulation in M. lupulina leaves. Moreover, we identified..
Spatial-temporal distribution and transport flux of polycyclic aromatic hydrocarbons in a large hydropower reservoir of Southeast China: Implication for impoundment impacts.
Get PDFIn order to investigate the impacts of dam-related water impoundment on the spatial-temporal variations and transport of anthropogenic organic pollutants, 15 priority polycyclic aromatic hydrocarbons (PAHs) were analyzed in water samples from the Shuikou Reservoir (SKR) of the Minjiang River. The SKR was formed after the construction of the Shuikou Dam, which is the largest hydropower station in Southeast China. The water samples were collected from the backwater zone of the SKR, in both the wet and dry seasons, corresponding to the drainage and impoundment periods of water flow, respectively. The concentrations of the dissolved PAHs in surface water from the wet season (average of 161 ± 97 ng L-1) were significantly higher (ANOVA, p < 0.01) than those from the dry season (average of 43 ± 21 ng L-1). PAH concentrations in the SKR decreased from upstream (industrialized cities) to downstream (rural towns or counties), indicating high PAH loads caused by intensive urbanization effects. The high proportions of 3-ring PAHs in the wet season were from local sources via surface runoff; while the elevated proportions of 4- to 6- ring PAHs in the dry season reflected atmospheric deposition emerged of these PAHs and/or volatilization of 3-ring PAHs enhanced. Molecular diagnostic ratios of PAH isomers in multimedium and principal component analysis indicated that PAH presence in the SKR was mainly attributed to pyrogenic origin. The isomeric ratios of fluoranthene to fluoranthene plus pyrene in the wet season were homogeneous, implying that there were continuous new inputs along the riverine runoff. However, these ratios showed spatial downward trend in the dry season, indicating continued degradation of PAHs occurred along the transport path during the impoundment period. The input and output fluxes of PAHs in the SKR were 5330 kg yr-1 and 2991 kg yr-1, revealing that the reservoir retained contaminants after impoundment of the hydropower dam
Dissipation Theory-Based Ecological Protection and Restoration Scheme Construction for Reclamation Projects and Adjacent Marine Ecosystems.
Get PDFAccording to the 2017 results of the Special Inspector of Sea Reclamation, a substantial number of idle reclamation zones existed in 11 provinces (cities) along the coast of China. To improve the protection level of coastal wetlands and strictly control reclamation activities, it is necessary to carry out ecological restoration of reclamation projects and adjacent marine ecosystems. The characteristics of Guanghai Bay and its reclamation project are typical in China’s coastal areas, making it an optimal representative site for this study. The dissipative structure and entropy theory was used to analyze ecological problems and environmental threats. The analytic hierarchy process was applied to determine the order of the negative entropy flow importance. The entropy increase and decrease mechanism was used to determine an ecological protection and restoration scheme for the reclamation, including the reclamation of wetland resource restoration, shoreline landscape restoration, environmental pollution control, and marine biological resource restoration. Finally, based on system logic, a typical ecological restoration system was constructed east of Guanghai Bay, with the mangrove wetland area as the model in the north and the artificial sandbeach recreation area as the focus in the south
室内燃烧源排放颗粒物及多环芳烃的粒径分布研究
Get PDF室内燃烧源排放颗粒物及其多环芳烃（PAHs）的粒径分布是定量评估室内人群呼吸暴露风险的重要参数之一。该研究在再悬浮箱内模拟燃香、燃蚊香、艾灸和吸烟等过程,采用MOUDI采样器采集和分析颗粒物中17种PAHs;同时,采用颗粒物计数器,在实际房间中模拟艾灸和吸烟过程,得到室内颗粒物数浓度的衰减曲线。结果表明,燃烧源烟雾颗粒的排放因子为3.68～22.46 mg/g,颗粒质量粒径呈单峰型,峰值为0.25～0.44μm;US EPA 16种优控PAHs的排放因子为10.52～91.30μg/g,艾绒燃烧排放PAHs的粒径峰值为0.44～1.0μm,略大于其它燃烧源;<1μm颗粒中PAHs的BaP等效毒性当量(BaPTEQ)的贡献占比为85%～98%。来源特征比值的研究显示,艾灸、燃香和吸烟释放的PAHs均归属于生物质燃烧类别。实际室内监测显示,在艾绒和香烟燃烧后室内颗粒物数浓度快速上升,在燃尽时达到峰值,而后在4 h内呈指数规律衰减,且<0.3μm的细颗粒衰减最快。国家自然科学基金项目(41171365