离散多时滞系统时滞记忆鲁棒H_∞容错控制

针对具有多个时滞状态的线性不确定离散时间系统,基于李雅普诺夫稳定性理论和线性矩阵不等式方法（LMI）,采用有时滞记忆的状态反馈控制律,研究了执行器发生故障的情况下,不确定离散多时滞系统的鲁棒H∞容错控制问题.在采用离散执行器故障模型条件下,给出了没有干扰输入时,系统存在有时滞记忆的状态反馈鲁棒容错控制器的一个充分条件;...     

片式PTC热敏电阻瓷片再氧化工艺的研究

以乙酸钡(Ba(CH3COO)2)、钛酸四丁酯(Ti(OC4H9)4)和硝酸钇(Y(NO3)3.6H2O)为原料,采用溶胶-凝胶法制备掺1.6%(质量分数)施主钇(Y)的钛酸钡nm粉体.用此粉体制备叠层片式正温度系数热敏电阻(PTCR)用瓷片,其中用氮化硼(BN)和钛酸钡作为玻璃相原料.利用流延方法成型,流延生胚在体积分数为97%的N2和体积分数为3%的H2的还原气氛下烧结成瓷.通过采用不同的再氧化温度和时间去氧化烧成的瓷片,研究再氧化工艺对正温度系数(PTC)瓷片电性能的影响.结果显示:室温电阻率随再氧化温度的升高先增加后减小,而PTC效应逐渐增加;室温电阻率随再氧化时间的增加会出现一个最小值,再氧化时间对PTC效应影响不大;样品的耐压值随着再氧化温度或时间的增加而增大.     

灰离褶伞菌丝的生长营养和培养条件研究

研究了灰离褶伞(Lyophyllum cinerascens(Bull.et Konr.)Konr.& Maubl.)菌丝生长所需的碳氮营养及其培养条件.结果表明,适宜灰离褶伞菌丝生长的最佳碳源为蔗糖,最佳氮源为麦麸和蛋白胨,最佳碳氮比为5∶1～10∶1,最适温度为25℃,最适pH为6.0.     

Effects of inorganic arsenic on growth and microcystin production of a <Emphasis Type="Italic">Microcystis</Emphasis> strain isolated from an algal bloom in Dianchi Lake,China

Our previous data have shown that inorganic arsenic concentrations were high in Dianchi Lake, China, where Microcystis blooms often occur. To explore the relationship between arsenic and the growth of Microcystis, the effects of arsenite [As(III)] and arsenate [As(V)] on the growth and toxin production of M. aeruginosa strain FACHB 905 were tested. Results showed that M. aeruginosa FACHB 905 was tolerant to inorganic arsenic and its growth was not inhibited when the concentration of As(III) was below 10⁻⁵ mol L⁻¹ or that of As(V) below 10⁻³ mol L⁻¹. Total microcystin production was stimulated in the presence of 10⁻⁷ mol L⁻¹ As(III) and the response of this M. aeruginosa strain to As(III) seemed to be a typical inverted U-shaped hormesis. The content increase of microcystin-LR per cell indicated that the toxicity was enhanced as M. aeruginosa FACHB 905 was exposed to As(V). Considering the relatively high concentration of inorganic arsenic in Dianchi Lake (139 μg L⁻¹ in epilimnetic water), the origin of the M. aeruginosa strain, inorganic arsenic favors survival of M. aeruginosa FACHB 905 and may stimulate its microcystin production and cellular toxicity.     

Enhanced low-temperature performance of slight Mn-substituted LiFePO<Subscript>4</Subscript>/C cathode for lithium ion batteries

Low temperature performance of LiFePO₄/C cathode was remarkably improved by slight Mn-substitution. Electrochemical measurements showed that about 95% of the discharge capacity of LiFe_0.98Mn_0.02PO₄/C cathode at 20°C was obtained at 0°C, compared to 85% of that of LiFePO₄/C cathode. The LiFe_0.98Mn_0.02PO₄/C sample also presented enhanced rate performance at −20°C with the discharge capacities of 124.4 mA h/g (0.1C), 99.8 mA h/g (1C), 80.7mAh/g (2C) and 70 mA h/g (5C), respectively, while pristine LiFePO₄/C only delivered capacities of 120.5 mA h/g (0.1C), 90.7 mA h/g (1C), 70.4 mA h/g (2C) and 52.2 mA h/g (5C). Cyclic voltammetry measurements demonstrated an obvious improvement of the lithium insertion-extraction process of the LiFePO₄/C cathode by slight Mn-substitution. The results of FSEM observation and electrical conductivity measurement indicated that slight Mn-substitution minimized the particle size of LiFe_0.98Mn_0.02PO₄/C and also obviously improved the electrical conductivity of the compound, thus obviously enhances the interface reaction process on the cathode.     

毛泽东执政党建设思想探析

毛泽东针对党刚刚取得政权后的时代特点、党担负的任务以及党自身的状况,从论述加强执政党建设的极端重要性;注重执政党思想建设,用马克思列宁主义教育全党;执政党建设的根本任务是为党的政治路线服务;重视党风建设,反对和防止官僚主义;高度重视执政党的反腐倡廉建设,保持党的纯洁性等方面阐明了党的第一代领导集体的执政党建设理论,为党的执政党建设理论奠定了理论基础。     

足球运动中踝关节损伤的治疗及疗效对比

运动员关节损伤后如何有效治疗及使其尽快康复,具有重要意义。通过对山西路虎足球队冬训期间14名踝关节急性损伤的运动员运用按摩、针刺、中药离子导入疗法进行治疗,并对有中药离子导入与无中药离子导入的治疗进行对比,观察疗效。经过14 d治疗及康复,有中药离子导入疗法组有效率100%,平均治疗天数10 d;无中药离子导入疗法组有效率71.42%,平均治疗天数14 d。可见,中药离子导入配合手法按摩及针刺的疗法对踝关节急性损伤的治疗具有较好的效果。     

玉米丰产方综合配套技术之浅见

玉米是农业生产由粮食—经济作物的二元结构向粮食—饲料—经济作物三元结构转变中最具有战略性的作物之一,在粮食总产量中所占的比重份额越来越大。为了稳定国家粮食安全大局,应保障粮食有效供给和农民持续增收。以精量穴播技术为中心,将测土配方施肥、施用抗旱保水剂、加厚耕作层等多项技术集成,配合优良品种、病虫害综合防治和田间科学管理等常规农业技术,提高了综合地力、增加了粮食产量。平均单产比前3年增产11.11%,667 m2节约化肥投入30元,肥料利用率提高10%以上。     

涤纶纤维的等离子体变性

等离子体处理是使化学纤维变性的有效手段之一。本文表明,经低温等离子体处理过的涤纶纤维,其回潮率约增加50％—100％。放置一段时间后略有衰退。通过X光电子能谱以及激光喇曼光谱等对处理后试样的分析测试,探讨了吸湿性改变的机理,指出有极性基团出现,同时伴有结晶度的改变。处理后纤维强度基本不变。     

BNN晶体喇曼光谱的组分效应与晶格振动的群论分析

本文测定了两种不同组分BNN晶体(Ba_(2+x)Na_(1-2x)Nb_5O_(15),x为0.065及0.075)的喇曼光谱并对此晶体的晶格扳动进行了群论分析。实验及理论分析的结果表明:(1)在高频区内,若干谱峰的相对强度不随x值而改变,它们是NbO_3~(-1)八面体的内振动模;在低频区内,若干频峰的相对强度随Ba~(+2)组分的增加而增加.(2)对应于34~(-1)cm的特征模只能出现在B_1(T_o)模中,而不能在B_2(T_o)模中出现,它来源于某些特殊面上Ba~(+2)的振动。