DEAE-Sepharose Fast Flow柱层析对龙牙百合多糖纯化工艺研究

采用DEAE-Sepharose Fast Flow离子交换剂、4.6 cm×100 cm的层析柱,以多糖主峰的对称性、宽度和多糖得率为指标,筛选最佳上样量、流速和吸附时间,研究龙牙百合多糖的分离纯化工艺,探索快速、大量提纯百合多糖的方法和途径。结果表明:分离多糖工艺条件为上样量2 g、洗脱流速2 mL/min、吸附时间5 min,分离得2种多糖LLP1、LLP2,得率分别为33%、19.5%,总得率为52.5%,主峰尖锐、对称性好。

DEAE-Sepharose Fast Flow分离纯化刺芹侧耳木质素降解酶

[目的]为Pleurotus eryngii—Co60-7木质素降解酶的分离纯化和综合利用提供试验依据。[方法]采用DEAE—Sepharose^TM Fast Flow离子交换介质，分别考察缓冲液pH值、流速和洗脱方式等对刺芹侧耳木质素降解酶分离纯化的影响，确定了最佳分离纯化层析条件。[结果]DEAE-Sephalose^TM Fast Flow分离纯化Pleurotus eryngii-Co60-7木质素降解酶的最佳层析条件为：选择20mmol／L，pH值为5．0醋酸钠一醋酸缓冲体系，3ml／min的流速，进行分步洗脱（100、200～300和1000mmoL／L NaCl的三步洗脱），可较好地实现刺芹侧耳发酵液木质素降解酶初分，该纯化操作目标蛋白回收率达85％，纯化分离因素为2．71。[结论]该技术在分离纯化刺芹侧耳木质素降解酶上可行，具有潜在的工业应用价值。

Study on Separation of Phycoerythrin by Q-Sepharose Fast Flow

[Objective] This study aimed to establish an efficient process for separation of phycoerythrin by using Q Sepharose Fast Flow resin and verity its feasibility for scale-up. [Method] Elution gradient, sample volume and flow rate were optimized to determine the optimal separation condition, under which the scale-up process was verified. [Result] The optimal condition for separation of phycoerythrin by using Q Sepharose FF resin was investigated： 30 ml of laver extract was loaded to the Q Sepharose FF column with a bed volume of 8 ml; subsequently, the column was stepwise eluted with 0-0.10-0.35-1.00 mol/L NaCI solution （pH 6.0） at a constant flow rate of 1 ml/min; the elution peak under 0.35 mol/L NaCI solution was collected, and the recovery rate and purity coefficient （A565/A280） of phycoerythrin were determined as 44.3 and 1.15, respectively. Based on the established process, 75 ml of phycoerythrin extract was loaded to the Q Sepharose FF column with a bed volume of 20 ml for separation, while no significant variation was observed in the separation result. [Conclusion] Phycoerythrin can be well separated from laver extract by using Q Sepharose FF resin and the process is feasible for scale-up.

层析凝胶DEAE Sepharose Fast Flow分离纯化5’-混合脱氧单核苷酸

目的针对5’-混合脱氧单核苷酸的理化特性,研究利用DEAE Sepharose Fast F low凝胶分离纯化5’-混合脱氧单核苷酸。方法上样缓冲液采用20 mmol/L Tris,pH9.0,上柱量≤7.5mg/mL.gel,上柱流速5mL/m in,洗脱缓冲液采用20 mmol/LTris+0.025mol/L NaC l,pH 9.0,洗脱流速0.5mL/m in。结果实验结果发现dCMP,dAMP,dTMP的收率为95%以上,dGMP的收率为85%以上,所获得的混合脱氧单核苷酸经高效液相色谱检测色谱纯达98%以上。

Startup scheme optimization and flow instability of natural circulation lead-cooled fast reactor SNCLFR-100

Owing to the inherent instability of the natural circulation system,flow instability can easily occur during the operation of a natural circulation lead-cooled fast reactor,especially during the startup phase.A comprehensive startup scheme for SNCLFR-100,including primary and secondary circuits,is proposed in this paper.It references existing more mature startup schemes in various reactor types.It additionally considers the restriction conditions on the power increase in other schemes and the characteristics of lead-based coolant.On this basis,the multi-scale coupling code ATHLET-OpenFOAM was used to study the flow instability in the startup phase under different power-step amplitudes and power duration times.The results showed that obvious flow instability phenomena were found in the different startup schemes,such as the short-term backflow phenomenon of the core at the initial time of the startup.Moreover,an obvious increase in the flow rate and temperature to the peak value at the later stage of a continuous power rise was observed,as well as continuous oscillations before reaching a steady state.It was determined that the scheme with smaller power-step amplitude and a longer power duration time requires more time to start the reactor.Nevertheless,it will be more conducive to the safe and stable startup of the reactor.

Experimental study on the mechanism of flow blockage formation in fast reactor

Various sources of solid particles might exist in the coolant flow of a liquid metal cooled fast reactor(e.g.,through chemical interaction between the coolant and impurities,air,or water,through corrosion of structural materials,or from damaged/molten fuel).Such particles may cause flow blockage accidents in a fuel assembly,resulting in a reduction in coolant flow,which potentially causes a local temperature rise in the fuel cladding,cladding failure,and fuel melt.To understand the blockage formation mechanism,in this study,a series of simulated experiments was conducted by releasing different solid particles from a release device into a reducer pipe using gravity.Through detailed analyses,the influence of various experimental parameters(e.g.,particle diameter,capacity,shape,and static friction coefficient,and the diameter and height of the particle release nozzle)on the blockage characteristics(i.e.,blockage probability and position)was examined.Under the current range of experimental conditions,the blockage was significantly influenced by the aforementioned parameters.The ratio between the particle diameter and outlet size of the reducer pipe might be one of the determining factors governing the occurrence of blockage.Specifically,increasing the ratio enhanced blockage(i.e.,larger probability and higher position within the reducer pipe).Increasing the particle size,particle capacity,particle static friction coefficient,and particle release nozzle diameter led to a rise in the blockage probability;however,increasing the particle release nozzle height had a downward influence on the blockage probability.Finally,blockage was more likely to occur in non-spherical particles case than that of spherical particles.This study provides a large experimental database to promote an understanding of the flow blockage mechanism and improve the validation process of fast reactor safety analysis codes.

一种基于改进FAST角点检测的LK光流算法

针对传统LK光流法无法有效跟踪快速移动的目标,跟踪时存在特征点选取实时性和准确性不足的问题,提出一种结合改进FAST角点检测的LK光流算法。应用改进后的FAST角点检测提取出的角点作为候选特征点,通过设定筛选方案从中选取具有较高对比度的特征点作为目标特征点,结合图像金字塔分层,最终使用LK光流法对其进行跟踪。改进FAST角点检测能够更快速地提取出最强的灰度变化角点,使得子像素计算准确性得以提高并且减少了提取特征点的时间。引入图像分层缩放源图像,能够使算法稳定跟踪快速运动的目标。实验结果从运动目标检测所需时间、特征点的数量、每秒处理的视频帧数以及x轴和y轴方向运动误差等方面进行分析比较,证明所提出的改进算法运行速度快,能够快速且准确地跟踪动态目标。

基于历史流量的单向FAST TCP公平性改进算法研究

FASTTCP传输延时的估计是一个有待解决的问题.针对这些开放性问题,根据FASTTCP的单向加速应用特点,本文提出了一种新的传输层两层算法.一个活动的FASTTCP流的历史信息,如启动时间、运行时间等,在底层被记录下来.当新的FASTTCP流到达时,上层算法可以根据最早的FASTTCP流提供瓶颈链路的当前队列延时.传播延时的计算是以当前估测的最小往返延时与传播延时之差作为瓶颈链路的排队延时.最后,NS-2仿真结果验证了改进的两层算法的有效性.

模内贴标快餐碗微发泡模流仿真研究析

本文采用Moldex3D软件,模拟了带自锁射嘴、一模两腔、模内贴标快餐碗的微发泡工艺。分析了快餐碗的注塑压力、减重百分比及泡孔尺寸,与实际情况对比,有较好的准确性。

支管流致噪声干扰下的复值域EFastICA管道泄漏声定位技术研究

供水管网存在大量分支接头,流体在分支接头的分流作用下产生支管流致噪声,并通过管道与泄漏声信号进行耦合。针对支管流致噪声存在下的供水管道泄漏定位问题。提出一种基于高效快速独立主成分分析(efficient fast independent component analysis,EFastICA)技术的复值域高效快速独立主成分分析(complex efficient fast independent component analysis,C-EFastICA)技术,该算法将时域瞬时线性EFastICA技术的代价函数、约束函数、迭代规则等有效地扩展到复数域,实现对含支管流致噪声的泄漏声信号分解处理。与其他主成分分析(independent component analysis,ICA)类算法固定选择非线性函数不同的是,C-EFastICA根据声信号的广义高斯性特征,自适应地选择非线性函数建立代价函数和迭代学习规则,使得算法对混合信号的分离程度更高。试验结果表明,泄漏信号和支管流致噪声均是超高斯信号,经C-EFastICA分解得到的源泄漏信号对漏点的定位相对误差低于12%,低于传统同类的C-FastICA技术。

Simulation of the Clustering Phenomenon in a Fast Fluidized Bed: The Importance of Drag Correlation

Drag force is a key parameter in the numerical modeling of gas-particle flow in circulating fluidized beds. The reliability of current drag force correlations over the regime of fast fluidization has, however, not been thoroughly investigated. In this article, a drag force correlation accounting for the clustering effects for Geldart A particles is used to simulate the behaviors typical of fast fluidization, including dynamic evolution of clusters as well as time- averaged axial and lateral voidage profiles. Diverse images of clusters are captured and the time-averaged profiles of voidage are shown to be in quantitative agreement with the present empirical correlation. The results based on different constitutive correlations of drag force show the importance of the choice of drag force in modeling fast-fluidized beds. This drag force correlation, based on a simple averaging assumption, could give some basic insights about the magnitude of the drag reduction.

基于fast-LOF与光流轨迹的弱小目标检测算法

研究动态背景中弱小运动目标检测问题,提出了一种基于fast-LOF的光流轨迹分类方法。针对弱小运动目标占据像素少、特征缺失等问题,引入光流轨迹思想,在高维空间检测异常光流轨迹实现动态背景中弱小运动目标检测;针对传统LOF算法复杂度过高问题,引入fast-LOF降低异常检测环节复杂度,保证系统良好的检测效率。以手持摄像机拍摄视频进行实验,实验结果表明,白光场景中算法可以实现复杂大视场中弱小运动目标快速检测,光流轨迹和fast-LOF的结合有效提高了算法性能和检测效率,在视觉检测系统中具备一定使用价值。

A REACTIVE DYNAMIC CONTINUUM USER EQUILIBRIUM MODEL FOR BI-DIRECTIONAL PEDESTRIAN FLOWS

In this paper, a reactive dynamic user equilibrium model is extended to simulate two groups of pedestrians traveling on crossing paths in a continuous walking facility. Each group makes path choices to minimize the travel cost to its destination in a reactive manner based on instantaneous information. The model consists of a conservation law equation coupled with an Eikonal-type equation for each group. The velocity-density relationship of pedestrian movement is obtained via an experimental method. The model is solved using a finite volume method for the conservation law equation and a fast-marching method for the Eikonal-type equation on unstructured grids. The numerical results verify the rationality of the model and the validity of the numerical method. Based on this continuum model, a number of results, e.g., the formation of strips or moving clusters composed of pedestrians walking to the same destination, are also observed.

Experiments on particle cluster behaviors in a fast fluidized bed

A three-dimensional(3D) fast fluidized bed with the riser of 3.0 m in height and 0.1 m in inner diameter was established to experimentally study the cluster behaviors of Geldart B particles. Five kinds of quartz sand particles(dp= 0.100, 0.139, 0.177, 0.250 and 0.375 mm and ρp= 2480 kg·m^(-3)) were respectively investigated, with the total mass of the bed material kept as 10 kg. The superficial gas velocity in the riser ranges from 2.486 to 5.594 m·s^(-1) and the solid mass flux alters from 30 to 70 kg·((m^(-2)·s))^(-1). Cluster characteristics and evolutionary processes in the different positions of the riser were captured by the cluster visualization systems and analyzed by the self-developed binary image processing. The results found four typical cluster structures in the riser,i.e., the macro stripe-shaped cluster, saddle-shaped cluster, U-shaped cluster and the micro cluster. The increasing superficial gas velocity and particle sizes result in the increasing average cluster size and the decreasing cluster time fraction, while the solid mass flux in the riser have the reverse influences on the cluster size and time fraction. Additionally, clusters in the upper region of the riser often have the larger size and time fraction than that in the lower region. All these effects of operating conditions on clusters become less obvious when particle size is less than 0.100 mm.

Analysis of the Load Flow Problem in Power System Planning Studies

Load flow is an important tool used by power engineers for planning, to determine the best operation for a power system and exchange of power between utility companies. In order to have an efficient operating power system, it is necessary to determine which method is suitable and efficient for the system’s load flow analysis. A power flow analysis method may take a long time and therefore prevent achieving an accurate result to a power flow solution because of continuous changes in power demand and generations. This paper presents analysis of the load flow problem in power system planning studies. The numerical methods: Gauss-Seidel, Newton-Raphson and Fast Decoupled methods were compared for a power flow analysis solution. Simulation is carried out using Matlab for test cases of IEEE 9-Bus, IEEE 30-Bus and IEEE 57-Bus system. The simulation results were compared for number of iteration, computational time, tolerance value and convergence. The compared results show that Newton-Raphson is the most reliable method because it has the least number of iteration and converges faster.

快堆钠池传热流动计算程序 FASTOR-3D 的校验计算

为研究快堆钠池内的流动和传热，采用质量、动量、能量守恒方程和空隙率方法，建立了快堆钠池内三维流动和传热的数学模型，并利用ＳＩＭＰＬＥ计算方法编制了计算程序ＦＡＳ－ＴＯＲ－３Ｄ．由于钠池的结构非常复杂，任何一点的设计变动可能改变池内的传热特性，给整个快堆带来巨大的影响．选用了１０个比较有代表性的算例，从不同的侧面验证了ＦＡＳＴＯＲ－３Ｄ．计算结果表明，ＦＡＳＴＯＲ－３Ｄ的计算基础是正确的．对于复杂区域的三维流动和传热还有待于全真模型实验的进一步验证．

基于LK和FAST的时间序列图像快速配准算法

LK光流算法是一种精确高效的特征跟踪算法,能够较大幅度提高图像配准的精度和速度。针对时间序列图像的配准问题,基于LK光流算法,通过基于图像金字塔的方式跟踪改进后的FAST特征角点,采用一种鲁棒的单应矩阵估计算法解算配准参数,提出了一种基于LK光流和改进FAST特征的实时鲁棒配准算法。通过一组时间序列图像从配准精度和配准速度两个方面对所提出算法的性能进行了验证分析,平均重投影误差为0.16,平均处理速度为30 Hz。实验结果表明,该算法能够提取稳定的FAST角点,快速准确地跟踪匹配序列图像之间的特征,较好地解决时间序列图像的实时配准问题。

基于FAST-9角点与光流法的机载视频稳像算法

针对机载视频图像受载体姿态运动及抖动而出现的不稳定现象,提出FAST-9角点与光流法结合的电子稳像算法。首先对参考帧提取FAST-9角点,利用光流法在当前帧找到匹配特征点以求取帧间运动矢量。采用卡尔曼滤波计算出补偿分量,对各帧图像进行运动补偿。经过稳像前后的视频序列帧间差值对比可知,很好地去除了视频序列的抖动。

Quantitative analysis of intraspinal cerebrospinal fluid flow in normal adults

The present study quantitatively analyzed intraspinal cerebrospinal fluid flow patterns in 19 normal adults using fast cine phase-contrast magnetic resonance imaging. Results showed increased downward flow velocity and volume compared with upward flow, and the average downward flow volume of intraspinal cerebrospinal fluid decreased from top to bottom at different intervertebral disc levels. Upward and downward cerebrospinal fluid flow velocity reached a peak at the thoracic intraspinal anterior region, and velocity reached a minimum at the posterior region. Overall measurements revealed that mean upward and downward flow volume positively correlated with the subarachnoid area. Upward peak flow velocity and volume positively correlated with spinal anteroposterior diameter. However, downward peak flow velocity and volume exhibited a negative correlation with spinal anteroposterior diameter. Further flow measurements showed that flow velocity in upward and downward directions was associated with subarachnoid anteroposterior diameter, respectively. The present experimental results showed that cerebrospinal fluid flow velocity and volume varied at different intraspinal regions and were affected by subarachnoid space area and anteroposterior diameter size.