HPLC/ESI-MS分析淫羊藿黄酮苷类化合物

用HPLC/ESI-MS鉴定、分析淫羊藿黄酮苷类结构。80%乙醇提取,得到淫羊藿的有效成分,采用Sinochrom ODS-BP C18(4.6 mm×250 mm)分析柱,乙腈-水梯度洗脱,流速为1 mL.min-1,检测波长为270 nm,质谱记录总离子流图(TIC)。从淫羊藿醇提取物中鉴定出朝藿定A、Hexandraside F、朝藿定B、淫羊藿苷、箭藿苷A、2-″O-鼠李糖基.大花淫羊藿苷Ⅱ和宝藿苷等7个淫羊藿黄酮苷类化合物。结果表明,HPLC/ESI-MS能快速、准确地鉴定出淫羊藿中黄酮类成分,证明了淫羊藿苷类的有效部位中所含的成分主要为8-异戊烯基取代的黄酮苷类化合物。     

麦冬多糖水解酶的微生物筛选及其产酶条件

为了提高生物酶法水解麦冬粗多糖的能力,采用单因素研究方法,对菌株及菌体发酵条件,菌株产酶的酶反应条件进行了研究。结果表明,产酶微生物为Absidiasp.O84s菌株;诱导物为麦冬浸出液,麦冬浸出液在培养基中的体积分数为20%,发酵温度30℃,培养时间为6 d:酶反应的最适条件为40℃,6 h,pH 5,底物质量浓度为10 mg/mL。黏度法测定得到麦冬粗多糖的平均分子质量为67 000 u,其水解产物的平均分子质量为39 000 u。     

HZSM-5催化合成乙酸正丁酯

采用乙二胺为模板剂,偏铝酸钠为铝源,硅溶胶为硅源,在静态水热合成的条件下合成了ZSM-5分子筛,并对此分子筛进行XRD、SEMI、R表征。以此分子筛为催化剂,乙酸、正丁醇为原料,催化合成乙酸正丁酯。考察了影响乙酸正丁酯酯化反应的因素。结果表明,HZSM-5分子筛催化剂有催化活性高、性能稳定、与产品易分离、后处理简单、无腐蚀、易回收等优点。得出最佳反应条件为:催化剂活化温度为550℃,活化时间为4 h,催化剂用量为0.5 g。     

红麻硫酸盐浆H_2O_2漂白及纸基地膜白度的研究

对用于抄造纸基地膜的红麻全秆硫酸盐浆的H2O2漂白工艺进行了探讨。实验结果表明,单段过氧化氢对红麻原浆漂白的最佳工艺条件为:H2O23%,碱比1,时间1 h,温度70℃,DTPA 0.25%,MgSO40.05%,Na2SiO33%,浆浓10%。在该漂白条件下漂白所得的浆料,卡伯值从原浆的23.05降低到6.6,黏度由1 605 mL/g降低到1 331.33 mL/g,白度从原浆的20.2%ISO提高到56.3%ISO。经过实验进一步分析,纸基地膜的最佳白度为55%ISO~60%ISO。红麻全杆硫酸盐浆单段过氧化氢漂白后所达到的白度(56.3%ISO)完全满足抄造红麻纸基地膜的白度要求。     

Characteristic-based operator-splitting finite element method for Navier-Stokes equations

A new finite element method, which is the characteristic-based operator-splitting (CBOS) algorithm, is developed to solve Navier-Stokes (N-S) equations. In each time step, the equations are split into the diffusive part and the convective part by adopting the operator-splitting algorithm. For the diffusive part, the temporal discretization is performed by the backward difference method which yields an implicit scheme and the spatial discretization is performed by the standard Galerkin method. The convective...     

NUMERICAL SIMULATION OF HYDRODYNAMIC CHARACTERISTICS ON AN ARC CROWN WALL USING VOLUME OF FLUID METHOD BASED ON BFC

In the present study, a new algorithm based on the Volume Of Fluid (VOF) method is developed to simulate the hydrodynamic characteristics on an arc crown wall. Structured grids are generated by the coordinate transform method in an arbitrary complex region. The Navier-Stokes equations for two-dimensional incompressible viscous flows are discretized in the Body Fitted Coordinate (BFC) system. The transformed SIMPLE algorithm is proposed to modify the pressure-velocity field and a transformed VOF method is used to trace the free surface. Hydrodynamic characteristics on an arc crown wall are obtained by the improved numerical model based on the BFC system (BFC model). The velocity field, the pressure field and the time profiles of the water surface near the arc crown wall obtained by using the BFC model and the Cartesian model are compared. The BFC model is verified by experimental results.     

A HIGHER-ORDER NON-HYDROSTATIC MODEL FOR SIMULATING WAVE PROPAGATION OVER IRREGULAR BOTTOMS

A higher-order non-hydrostatic model is developed to simulate the wave propagation over irregular bottoms based on a vertical boundary-fitted coordinate system.In the model,an explicit projection method is adopted to solve the unsteady Euler equations.Advection terms are integrated explicitly with the MacCormack's scheme,with a second-order accuracy in both space and time.Two classical examples of surface wave propagation are used to demonstrate the capability of the model.It is found that the model with on...     

A Hidden-Removal Model of Dam Perspective Drawing

Aming at water conservancy project visualization,a hidden-removal method of dam perspective drawings is realized by building a hidden-removal mathematical model for overlapping points location to set up the hidden relationship among point and plane,plane and plane in space.On this basis,as an example of panel rockfill dam,a dam hidden-removal perspective drawing is generated in different directions and different visual angles through adapting VC++ and OpenGL visualizing technology.The results show that the data construction of the model is simple which can overcome the disadvantages of considerable and complicated calculation.This method also provides the new means to draw hidden-removal perspective drawings for those landforms and ground objects.     

移动机器人基于视觉室外自然场景理解的研究与进展

对于工作在典型非结构化场景中的移动机器人系统, 具有良好的室外自然场景感知与理解能力是其能够自主运行的前提条件. 移动机器人使用视觉传感器来进行室外自然场景的理解一直是该领域的研究热点. 本文首先介绍了基于视觉的移动机器人自然场景理解的研究现状, 对其相关子领域的研究思路与前沿技术进行了着重论述与分析, 并从实时性和环境自适应性等方面对相关技术的实用性问题加以讨论. 最后对该领域的研究重点和技术发展趋势进行了探讨.     

基于Kalman滤波的储备池多元时间序列在线预报器

针对多元非线性时间序列, 结合回声状态网络和Kalman滤波提出一种新的在线自适应预报方法. 该方法将Kalman滤波应用于回声状态网络储备池高维状态空间中, 直接对网络的输出权值进行在线更新, 省去了传统递归网络扩展Kalman滤波中Jacobian矩阵的计算, 在提高预测精度的同时令算法的适用范围得到扩展. 在回声状态网络稳定时给出所提算法的收敛性证明. 仿真实例验证了所提方法的有效性.