悬浮液直接进样-火焰原子吸收法测定土壤中的铜

将悬浮液直接进样技术应用于火焰原子吸收光谱法对土壤中铜的测定，探讨了介质酸度以及悬浮液浓度对测定结果的影响，并与采用湿法处理的样品测定结果进行了比较，结果令人满意。     

火焰原子吸收光谱法连续测定葵花子中铜和锌

原子吸收光谱法可直接测定许多金属元素 ,但每一元素的分析条件各不相同 ,难以同时进行多元素分析。而火焰原子吸收光谱法能在同一体系中连续测定葵花子中铜和锌。经试验证明 ,在选定的工作条件下 ,用火焰原子吸收光谱法在同一体系中连续测定葵花子中铜和锌元素 ,RSD达到 0 .5 8% -0 .72 % ,回收率 99.0 % - 10 0 .3% ,具有良好的精确度和准确度 ,方法快速简便     

微乳液进样-火焰原子吸收光谱测定食用油中的钙

提出了以微乳液进样-火焰原子吸收光谱测定食用油中痕量钙的新方法.以OP-乳化剂为表面活性剂、正丁醇为助表面活性剂,以花生油、芝麻油为研究对象,优化了微乳液的形成条件及火焰原子吸收的测定参数.结果表明:V(油样)∶V(水相)∶V(OP-乳化剂)∶V(正丁醇)=1∶0.5∶0.6∶7.9时,能形成稳定的微乳液体系.以微乳液进样-火焰原子吸收光谱(标准加入法)测定花生油、芝麻油中的痕量钙,其回收率在96%~116%之间;采用微乳液进样的测定结果与干灰化法消化样品后的测定结果吻合良好.     

悬浮液进样GFAAS法测定地质样品中的痕量镉

提出了悬浮液进样石墨炉原子吸收(GFAAS)法测定地质样品中痕量镉的分析方法.研究了悬浮液的制备方法以及改进基体改进剂对测定的影响,确定了最佳实验条件.在最佳实验条件下,该方法的检出限为2.1 pg/g,测定范围为0～4.0 μg·L-1,回收率为95%～99%,精密度(RSD,n=4)为3.03%～5.40%.该方法快速、简便、干扰小,经对国家一级地质标准物质分析,结果满意.     

悬浮液进样GFAAS法测定地质样品中的痕量镉

提出了悬浮液进样石墨炉原子吸收(GFAAS)法测定地质样品中痕量镉的分析方法.研究了悬浮液的制备方法以及改进基体改进剂对测定的影响,确定了最佳实验条件.在最佳实验条件下,该方法的检出限为2.1pg/g,测定范围为0～4.0μg·L-1,回收率为95%～99%,精密度(RSD,n=4)为3.03%～5.40%.该方法快速、简便、干扰小,经对国家一级地质标准物质分析,结果满意.     

原子吸收光谱法间接测定苯丙氨酸

新生成的ZnS悬浮液与苯丙氨酸在碱性条件下,可以反应生成可溶性碱式苯丙氨酸锌配合物,用塞曼原子吸收光谱测定配合物溶液中的总锌质量浓度即可间接地得到苯丙氨酸的质量分数.拟定了原子吸收间接测定苯丙氨酸的最佳条件和方法,在pH 9.0的2%硼砂底液中于室温下使苯丙氨酸试液与新生成的ZnS悬浮液反应22 min,离心分离后测定上层清液的FAAS响应.在所选定的条件下苯丙氨酸测定的线性质量浓度范围为0~23 mg/mL,特征质量浓度为0.226 mg/mL,检测限质量浓度为0.829 mg/mL.该法用于样品中的苯丙氨酸测定,其相对标准偏差RSD为3.56%,方法的收率在91%~109%之间.并对测定机理进行了探讨.     

甲醇、汽油和甲醇/汽油-空气层流火焰传播速度的实验研究

在一个大气压和温度523K条件下,采用圆管法,对甲醇、汽油(70~#)和甲醇/汽油(70~#)(摩尔比1∶1)-空气的层流火焰传播速度进行了测定.实验发现,同等条件下,汽油(70~#)的层流火焰传播速度基本上小于甲醇的层流火焰传播速度;在相当宽的当量比φ值范围内,汽油/甲醇(摩尔比1∶1)-空气的层流火焰传播速度比汽油(70~#)-空气和甲醇-空气的层流火焰传播速度低.     

原子吸收光谱法间接测定半胱氨酸

利用新生成的ZnS悬浮液与半胱氨酸在碱性条件下,反应生成可溶性半胱氨酸锌络合物,离心分离后用塞曼原子吸收光谱测定溶液中的锌质量浓度即可间接的得到半胱氨酸的含量.研究选择了原子吸收间接测定半胱氨酸的最佳条件和方法,在pH 9.70的2% 硼砂底液中于室温下使半胱氨酸试液与新生成的ZnS悬浮液反应25 min,离心分离后测定上层清液的FAAS响应.在所选定的条件下半胱氨酸测定的线性质量浓度范围为0～80 μg·mL-1,特征质量浓度为0.718 μg·mL-1,检测限为0.76 μg·mL-1.该法用于样品液中的半胱氨酸测定,其相对标准偏差RSD为0.58%,方法的回收率在97%～103%之间.并对测定机理进行了探讨.     

电收尘吸收液中微量Zn的测定

建立了空气-乙炔原子吸收法测定电收尘吸收液中微量Zn的体积质量.在酸性介质中,采用湿式法酸解电收尘吸收液试样,用空气-乙炔火焰原子吸收光谱法,在氢氧化钾-肥皂尘吸收液中测定了微量Zn的体积质量.该方法灵敏度、精密度高,选择性好,试剂消耗量少.Zn的回收率为95%～113%,相对标准偏差为0.91%,能满足冶炼湿式电收尘吸收液的分析要求.     

原子捕获火焰原子吸收光谱测定皮革中的痕量铬

采用单缝式原子捕获石英管在火焰原子吸收光谱仪上测定皮革中的痕量铬,考察了捕获时间、乙炔流量等测试条件的影响.实验表明,本方法的灵敏度比火焰原子吸收光谱法灵敏度提高了4.5倍,相对标准偏差为1.56%,加标回收率为96.7%～103.0%,检出限可达0.02 μg/mL,测定皮革中的痕量铬获得了满意的结果.     

Preparation of the preform of pure carbon reaction bonded silicon carbide by<Emphasis Type="Italic">in-situ</Emphasis> consolidation molding method

A new kind of in-situ ceramic consolidation molding process was investigated on the basis of the characteristics of starch swelling in water and gelatinizing when heated. The SiC ceramic suspension containing about 50vol% solids loading and about 3wt% starch can be cast and molded into various complex-shape SiC ceramic parts in a water-thermostat. The dry shrinkage of the green body was less than 1.0% when the solid volume fraction of SiC suspension was up to 52.5%. The density and pore size were homogeneously distributed inside the biscuits. Soaked with melt silicon in a vacuum arc furnace, the biscuits were turn into SiC ceramic materials with homogeneous structure and high performances. Li Mei-juan: Born in 1969 Funded by the Key Research Project of China (96-A10-01-07) and the Key Project of Wuhan Science and Technology Committee (20001001003)     

Lead removal from aqueous solution by employing natural brucite

The effect and mechanism of the removal of Pb^2 from an aqueous solution by using brucite as the adsorbent were studied. It was revealed that the increase in pH of brucite suspension, as a result of the release of magnesium hydroxide into the suspension, leads to a sharp rise of the adsorption amount of Pb^2 on brucite. The synergism of buffering and adsorption capacities of brucite is responsible for the removal of Pb^2 from the aqueous solution. The coexistence of Cu^2 with Pb^2 causes a decrease of their adsorption on brucite due to a competition for surface sites and brucite exhibits a higher adsorption capacity for Pb^2 than for Cu^2 . The percentage adsorption of Pb^2 on brucite could reach 96.38%, 97.20% and 94.09% respectively with the initial pH of the suspension pHi= 1,76 (initial Pb^2 concentration [Pb^2 ]i = 20μmol/L), 1.82 ([Pb^2 ]i=100μmol/L ) and 1.84 ([Pb^2 ]i = 500 μmol/L). It was concluded that brucite is a very efficient mineral adsorbent for Pb^2 removal from polluted acidic water.     

Preparation of the Preform of Pure Carbon Reaction Bonded Silicon Carbide by In-situ Consolidation Molding Method

A new kind of in-situ ceramic eonsolidation molding process was imvestigated on the basis of the characteristics of stareh swelling in water and gelutinizing when heuted. The SiC ceramic snspension containing about 50wt% solids loading amt about 3wt% starch can be cast amt molded into various complex-shape SiC ceramic parts in a wuter-thermostat. The dry shrinkage of the green body was less than 1.0% when the solid volume fraction of SiC suspension was up to 52.5% . The density and pore size were homogeneously distributed insule the biscuits. Soaked with melt silicon in a vacuum are furnace, the biscuits were turn into SiC ceramic materiols with homogeneous structure and high performances.     

车辆半主动悬架的仿真研究

提出了一种根据车速，路谱和载荷实时调节悬架参数的产主动悬架设计方案。将车辆模化为七自由度振动系统，采用频域法进行随机响应计算，仿真结果表明同传统的被动悬架相比这种半主动悬架可使车身振动显著减小，提高了平顺性和操纵稳定性。     

混凝土自锚式悬索桥结构内力分析

为研究混凝土自锚式悬索桥的结构受力特征以及与地锚式悬索桥的差别。通过计算实例，分析比较混凝土自锚式悬索桥结构的力学特性，研究其拱度、矢跨比变化时引起的内力变化规律，混凝土收缩、徐变对内力影响的规律。对于中小跨度的自锚式悬索桥来讲，除了主梁的轴力偏大以外，结构的其余内力与地锚式悬索桥的差别不是很大，差值在10％以内。拱度和混凝土的收缩、徐变的影响比较明显。与相应的水平加劲梁和不考虑收缩、徐变影响的计算结果比较，差值均在20％以上。弹性理论适合于中小跨度的自锚式悬索桥的设计和计算。     

混凝土自锚式悬索桥结构内力分析

为研究混凝土自锚式悬索桥的结构受力特征以及与地锚式悬索桥的差别,通过计算实例,分析比较混凝土自锚式悬索桥结构的力学特性,研究其拱度、矢跨比变化时引起的内力变化规律,混凝土收缩、徐变对内力影响的规律.对于中小跨度的自锚式悬索桥来讲,除了主梁的轴力偏大以外,结构的其余内力与地锚式悬索桥的差别不是很大,差值在10％以内.拱度和混凝土的收缩、徐变的影响比较明显.与相应的水平加劲梁和不考虑收缩、徐变影响的计算结果比较,差值均在20％以上.弹性理论适合干中小跨度的自锚式悬索桥的设计和计算.     

利用有益非线性因素的主动式悬架系统饱和PD-SMC跟踪方法

针对具有输入饱和的主动式悬架系统,通过利用所构建的仿生参考模型的非线性刚度和阻尼,设计了一种新颖的饱和PD−滑模控制方法(饱和PD-SMC方法)。所设计的控制方法具有以下几个优点：具有PD控制方法的简单结构;具有SMC方法针对模型不确定性和外部干扰的强鲁棒性;不需要传统SMC方法所要求的精确系统参数;同时充分考虑输入饱和的影响。在所设计的控制方法中,PD部分用于保证主动式悬架系统的稳定,SMC部分用于提供强鲁棒性,并引入饱和函数防止控制输入超过约束范围。利用李雅普诺夫方法保证了相应的稳定性分析。从多个实验结果可以看出,与现有的控制方法相比,所设计的控制方法显著提高了暂态性能,并节省了30.65%的控制能量。     

基于联合仿真技术的半主动悬架混合控制策略研究

为减少汽车半主动悬架系统开发周期和成本,利用多体动力学仿真软件SIM—PACK建立了某轿车单斜臂式悬架虚拟样机模型,并在MATLAB／SIMULINK环境中设计了基于混合控制策略的半主动悬架控制器,建立了一个半主动悬架控制策略研究的集成环境,利用该集成环境研究了基于混合控制策略的半主动悬架车辆行驶性能。与被动悬架相比,当汽车以72km／h在B级路面上行驶,阻尼力分配系数a为0．6时,混合控制策略下的半主动悬架车身垂向加速度均方根值和悬架动行程均方根值分别下降了17．38％和43．24％,而轮胎动载荷均方根值仅增加了4．42％。研究结果表明,基于混合控制策略的半主动悬架可以有效衰减车身的振动,改善车辆行驶平顺性,而车辆道路友好性并没有发生恶化。     

Analyses and Simulation of Fuzzy Logic Control for Suspension System of a Track Vehicle

The vibration caused by terrible road excitation affects the ride quality and safety of track vehicles.The vibration control of suspension systems is a very important factor for modern track vehicles.A fuzzy logic control for suspension system of a track vehicle is presented.A mechanical model and a system of differential equations of motion taking account of the mass of loading wheel are established.Then the fuzzy logic control is applied to control the vibration of suspension system of track vehicles for sine signal and random road surfaces.Numerical simulation shows that the maximum acceleration of suspension system can be reduced to 44% of the original value for sine signal road surface,and the mean square root of acceleration of suspension system can be reduced to 21% for random road surface.Therefore,the proposed fuzzy logic control is an efficient method for the suspension systems of track vehicles.     

Study of Vertical Seismic Response of Concrete Self-Anchored Suspension Bridges

Based on the variational prineiple of incomplete generalized potential energy with large deflection, the vertical nonlinear vibrational differential equation of self-anchored suspension bridge is presented by taking the effect of coupling of flexural and axial action into consideration. The linear vertical equation is obtained by omitting the nonlinear term, and the pseudo excitation method(PEM). Taking the self-anchored concrete suspension bridge over Lanqi Songhua river for an example, the expected peak responses of main beam, towers and cables are calculated. And the seismic spatial effects on vertical seismic response of self-anchored suspension bridges are discussed.