永磁型无轴承电机悬浮系统的PID-PD控制

PID控制器被广泛应用于控制各种稳定的系统,其参数可采用Ziegler Nichols的方法进行确定,但对于不稳定系统采用PID控制,一般需进行大量的调试工作.此处采用双环PID控制,先将系统内环转化为稳定的控制模型,再通过外环控制器改善系统性能,针对永磁型无轴承电机(PMBM)的数学模型,设计了PID -PD控制器....     

基于特色化建设的工程管理专业本科培养方案优化研究

从特色化的角度指出我国高校工程管理专业本科培养方案存在的问题,分析问题成因,并基于特色化建设,着眼优化提出工程管理专业人才培养方案的改进建议,为我国高校工程管理专业本科培养教育方案的制定提供参考。     

客户用电安全服务的实践与探索

随着城市配电网的不断完善,客户端用电设备健康水平高低已成为配电网安全运行的重要影响因素。供电企业根据自身特点,针对不同的客户群体采取差异化服务的方式,在加强客户用电安全服务、提高供电可靠性方面进行了有益的探索．在保障配电网安全运行的同时也赢得了社会和客户对供电服务的认可。     

火山岩风化壳及油气地质意义——以新疆北部石炭系火山岩风化壳为例

以新疆北部石炭系火山岩风化壳为例,利用露头、岩心、试油和测井等资料,研究火山岩风化壳特征、分布及油气地质意义。完整火山岩风化壳具有6层结构,即土壤层、水解带、淋蚀带、崩解Ⅰ带、崩解Ⅱ带和母岩,不同结构层具有不同特征和识别标志,有利储集层主要发育于淋蚀带和崩解Ⅰ带内。风化淋蚀时间控制风化壳厚度,火山岩风化壳最大厚度可达550 m,形成时间约46.3 Ma;岩性、岩相、风化程度控制风化壳储集层物性;断裂控制风化壳储集层渗流能力,越靠近断裂渗流半径和渗流能力越大。火山岩风化壳主要分布于古地貌高部位、斜坡带及断裂发育的低洼部位;靠近断裂区油层垂向跨度大。建立火山岩风化程度和有效储集层评价方法和模型,可利用测井资料评价未取心井钻遇的火山岩风化壳风化程度及有效储集层。     

Shrinkage-free preparation of scaffold-free cartilage-like disk-shaped cell sheet using human bone marrow mesenchymal stem cells

Aiming for the clinical application of cartilage regeneration, a culture method for mesenchymal stem cells (MSCs) derived from human bone marrow to obtain scaffold-free cartilage-like disk-shaped sheet of uniform sizes without the shrinkage was investigated. A disk-shaped cell sheet having the same diameter as that of the membrane without the shrinkage was formed after the cultivation of MSCs (18.6 × 10(5)cells/well) for 3 weeks in a cell culture insert (CCI) containing a flat membrane whose porosity was 12%, while 6.2 and 31.0 × 10(5)MSCs/well, respectively, resulted in the shrinkage of the aggregate and the hole formation in the center part of the sheet. Cell aggregates shrunk also in a 96-well plate and CCIs having lower porosity. The disk-shaped cell sheet showed the comparable thickness (1.2mm) and sulfated glycosaminoglycan (sGAG) density to those of the pellet formed in a pellet culture. The gene expression levels of aggrecan and type II collagen in the disk-shaped cell sheet were not lower than those in the pellet. In conclusion, the usage of CCI having 12% porosity and 18.6 × 10(5)MSCs/well could avoid the shrinkage from the formation of the scaffold-free cartilage-like disk-shaped cell sheet.     

Rapid Differentiation of Listeria monocytogenes Epidemic Clones III and IV and Their Intact Compared with Heat‐Killed Populations Using Fourier Transform Infrared Spectroscopy and Chemometrics

The objectives of this study were to determine if Fourier transform infrared (FT‐IR) spectroscopy and multivariate statistical analysis (chemometrics) could be used to rapidly differentiate epidemic clones (ECs) of Listeria monocytogenes, as well as their intact compared with heat‐killed populations. FT‐IR spectra were collected from dried thin smears on infrared slides prepared from aliquots of 10 μL of each L. monocytogenes ECs (ECIII: J1‐101 and R2‐499; ECIV: J1‐129 and J1‐220), and also from intact and heat‐killed cell populations of each EC strain using 250 scans at a resolution of 4 cm^?1 in the mid‐infrared region in a reflectance mode. Chemometric analysis of spectra involved the application of the multivariate discriminant method for canonical variate analysis (CVA) and linear discriminant analysis (LDA). CVA of the spectra in the wavelength region 4000 to 600 cm^?1 separated the EC strains while LDA resulted in a 100% accurate classification of all spectra in the data set. Further, CVA separated intact and heat‐killed cells of each EC strain and there was 100% accuracy in the classification of all spectra when LDA was applied. FT‐IR spectral wavenumbers 1650 to 1390 cm^?1 were used to separate heat‐killed and intact populations of L. monocytogenes. The FT‐IR spectroscopy method allowed discrimination between strains that belong to the same EC. FT‐IR is a highly discriminatory and reproducible method that can be used for the rapid subtyping of L. monocytogenes, as well as for the detection of live compared with dead populations of the organism.     

Differentiation of mouse embryonic stem cells into neurons using conditioned medium of dorsal root ganglia

Mouse embryonic stem (ES) cells, which are continuously growing cell lines, have a pluripotent ability to differentiate into various cell lineages in vitro including neurons. We investigated the effects of chick dorsal root ganglion (DRG) conditioned medium (CM) and nerve growth factor (NGF) on the directed differentiation of ES cells into neurons. Because DRGs from 8-day-old chick embryos are often used in bioassays of neurotrophic factors, DRGs may release soluble factors that can induce ES cell differentiation into neurons in a culture broth. When cultivated in a Dulbecco's modified Eagle's medium (DMEM)/F-12K medium containing DRG-CM or NGF, the ES cell colonies clearly showed neurite outgrowths. Of particular significance, the immunofluorescence analysis of ES cell colonies using an anti-betaIII-tubulin antibody indicated that the addition of DRG-CM effectively promoted the differentiation of ES cells into neurons. We confirmed the effect of DRG-CM addition on ES cell differentiation into neurons via neuronal stem cells by the immunofluorescence analysis of ES cell colonies. Thus, DRG-CM appeared to effectively promote ES cell differentiation into neurons.     

儿童肥胖症中医治疗的进展

目的综述儿童肥胖病中医治疗的进展。方法总结近年中药辨证论治、专方、单方与针灸推拿治疗儿童肥胖病的成果。结果与结论中医药治疗儿童肥胖具有独特的优势,开展循证医学研究和规范中医药疗法具有非常重要的临床价值。     

多不饱和脂肪酸对小鼠3T3-L1前脂肪细胞增殖和分化的影响

本文利用MTS比色分析法、细胞形态学分析法及诱导分化法结合油红染色比色分析法研究了α-亚麻酸(alpha-linolenic acid,ALA)、亚油酸(linoleic acid,LA)对3T3-L1前脂肪细胞增殖及分化的影响。MTS结果显示,在一定浓度范围内ALA、LA均能呈剂量依赖关系和时间依赖关系的抑制3T3-L1前脂肪细胞的增殖,且ALA抑制增殖作用强于LA;细胞形态学分析结果显示,ALA、LA在高浓度时均显示出细胞毒性作用;倒置显微镜观察和油红染色检测结果显示,ALA、LA、ALA/LA混合脂肪酸(1:1,n/n)在12.5~200μmol/L浓度范围内均能浓度依赖式的抑制3T3-L1前脂肪细胞分化,且ALA抑制分化作用强于LA,但当浓度100μmol/L时,ALA/LA混合脂肪酸(1:1,n/n)的抑制分化作用强于同浓度的ALA,当浓度为200μmol/L时,比较ALA/LA摩尔比为1:4、1:2、1:1的混合脂肪酸抑制分化效果发现,比值为1:1的略强但相互之间效果差异不明显。     

差别化土地利用策略在新一轮土地利用规划中的运用——以重庆市为例

区域经济社会发展的不平衡性和自然条件、资源禀赋的相似性与差异性要求制定与之相配套的区域土地利用战略。运用文献资料法和定性分析法,可将重庆市划分为都市城镇核心区、都市城郊发展区、三峡生态保育区、武陵农业发展区。通过差别化土地利用策略的区域指引,从土地利用策略中心、生态屏障建设、基本农田调整、新增建设用地4方面对各区域土地利用进行调整,对改善城乡二元结构矛盾、实现和谐的人地关系和统筹城乡发展有较好的促进作用。