激光多谱勒测流术评述

在日常临床医学及微血管研究中,对徽循环中的血流测量来讲,激光多谱勒测流术(LDF)是一有效而又可靠的方法,这主要是因为LDF能对微血管中的血流进行连续、非损伤及实时测量。利用LDF测量皮肤灌注的医生往往不知道这种方法的局限性。本文的目的是介绍一些LDF用户所面临的困难以引起公众的注意。并提出一些方法以期将来能解决所存在的问题。

Ultrafast Carrier Dynamics in CdSe/CdS/ZnS Quantum Dots

The intra- and inter-band relaxation dynamics of CdSe/CdS/ZnS core/shell/shell quantum dots are investigated with the aid of time-resolved nonlinear transmission spectra which are obtained using femtosecond pump-probe technique. By selectively exciting the core and shell carrier, the dynamics are studied in detail. Carrier relaxation is found faster in the conduction band of the CdS shell （about 130 fs） than that in the conduction band of the CdSe core （about 400 fs）. From the experiments it is distinctly demonstrated the existence of the defect states in the interface between the CdSe core and the CdS shell, indicating that ultrafast spectroscopy might be a suitable tool in studying interface and surface morphology properties in nanosystems.

Experimental Study on Hydrodynamics of L-type Podded Propulsor in Straight-ahead Motion and Off-Design Conditions

Experimental tests were conducted to evaluate the hydrodynamic performance of an L-type podded propulsor in straight-ahead motion and off-design conditions using an open-water measuring instrument developed by the authors for podded propulsors, a ship model towing tank, and under water particle image velocimetry （PIV） measurement systems. Under the three types of conditions, the main parameters of an L-type podded propulsor were measured, including the propeller thrust and torque, as well as the thrust, side force, and moment of the whole pod unit.In addition, the flow field on the section between the propeller and the strut was analyzed. Experimental results demonstrate that the dynamic azimuthing rate and direction and the turning direction affect the forces on the propeller and the whole pod unit. Forces are asymmetrically distributed between the left and right azimuthing directions because of the effect of propeller rotation. The findings of this study provide a foundation for further research on L-type podded propulsors.

Effects of the Blade Shape on the Trailing Vortices in Liquid Flow Generated by Disc Turbines

Particle image velocimetry technique was used to analyze the trailing vortices and elucidate their rela-tionship with turbulence properties in a stirred tank of 0.48 m diameter,agitated by four different disc turbines,in-cluding Rushton turbine,concaved blade disk turbine,half elliptical blade disk turbine,and parabolic blade disk turbine.Phase-averaged and phase-resolved flow fields near the impeller blades were measured and the structure of trailing vortices was studied in detail.The location,size and strength of vortices were determined by the simplified λ2-criterion and the results showed that the blade shape had great effect on the trailing vortex characteristics.The larger curvature resulted in longer residence time of the vortex at the impeller tip,bigger distance between the upper and lower vortices and longer vortex life,also leads to smaller and stronger vortices.In addition,the turbulent ki-netic energy and turbulent energy dissipation in the discharge flow were determined and discussed.High turbulent kinetic energy and turbulent energy dissipation regions were located between the upper and lower vortices and moved along with them.Although restricted to single phase flow,the presented results are essential for reliable de-sign and scale-up of stirred tank with disc turbines.

DETECTION OF PLATELET-DERIVED MICROPARTICLES USING FLOW CYTOMETRY AND ITS CLINICAL APPLICATION

Objective.To establish a flow cytometric internal standard method for counting platelet-derived microparti-cles(PMPs)and to study its clinical significance. Methods. PMPs suspension(platelet poor plasma,PPP) was extracted by gradual centrifugation. According to the size of PMPs,3 μm and 0.8μm latex beads were used as internal standards for the quantitation. PMPs were counted by adjusting flow cytometric discrimination and voltage of forward scatter and side scatter. Results. In 30 healthy donors,the average concentration of resting PMPs was(1.2×105±5.7×104 )/ml and that of activated PMPs was(1.6×106±9.1×105)/ml. Compared with healthy donors,PMPs mean value was significantly higher(P< 0.001)in 18 patients with coronary artery disease,12 with acute cerebral infraction and 23 with chronic renal failure[the average PMPs concentration,( 6.1×105±2.5×105 )/ml, ( 6.8×105±3.4×105)/ml and(5.9×105±3.1×105)/ml respectively]. However,no significant difference in PMPs concentration was observed in 25 patients with acute leukemia and severe thrombocytopenia during the aplastic phase after chemotherapy [1.3×105±6.1×104)/ml,(P >0.05)] .Conclusions. PMPs is a useful indicator in monitoring platelet activation,and plays an important role in thrombotic disease. By flow cytometric internal standard method,PMPs can be counted rapidly and accurately,which may be very helpful in interlaboratory comparative studies.

A two-stage short-term traffic flow prediction method based on AVL and AKNN techniques

Short-term traffic flow prediction is one of the essential issues in intelligent transportation systems(ITS). A new two-stage traffic flow prediction method named AKNN-AVL method is presented, which combines an advanced k-nearest neighbor(AKNN)method and balanced binary tree(AVL) data structure to improve the prediction accuracy. The AKNN method uses pattern recognition two times in the searching process, which considers the previous sequences of traffic flow to forecast the future traffic state. Clustering method and balanced binary tree technique are introduced to build case database to reduce the searching time. To illustrate the effects of these developments, the accuracies performance of AKNN-AVL method, k-nearest neighbor(KNN) method and the auto-regressive and moving average(ARMA) method are compared. These methods are calibrated and evaluated by the real-time data from a freeway traffic detector near North 3rd Ring Road in Beijing under both normal and incident traffic conditions.The comparisons show that the AKNN-AVL method with the optimal neighbor and pattern size outperforms both KNN method and ARMA method under both normal and incident traffic conditions. In addition, the combinations of clustering method and balanced binary tree technique to the prediction method can increase the searching speed and respond rapidly to case database fluctuations.

Monitoring and Warning of Landslides and Debris Flows Using an Optical Fiber Sensor Technology

Landslides and debris flows are typical geo-hazards which occur in hilly or mountainous regions. Debris flows may result from landslides. Geotechnical instrumentation plays an important role in monitoring and warning of landslides and resulted debris flows. Traditional technologies for monitoring landslides and debris flows have certain limitations. The new optical fiber sensors presented in this paper can overcome those limitations. This paper presents two new optical fiber sensor systems: one is the Fiber Bragg Grating (FBG)-based in-place inclinometer for monitoring landslides and the other is the FBG-based column-net system for monitoring debris flows. This paper presents the calibration results of FBG-based in-place inclinometers in laboratory. It is found that the calibration results are in good agreement with theoretical results. Both the FBG-based in-place inclinometers and the FBG-based column-net system have been installed at a site in Weijiagou valley, Beichuan County, Sichuan Province of China. Some preliminary results have been obtained and reported in the paper. The advantages of the FBG monitoring systems and their potential applications are also presented.

The turbulent behavior of novel free triple-impinging jets with large jet spacing by means of particle image velocimetry

A novel reactor that achieves rapid liquid–liquid mixing via free triple-impinging jets(FTIJs) is developed to improve mixing efficiency at unequal flow rates for liquid–liquid reactions. The flow characteristics of FTIJs were investigated using particle image velocimetry(PIV). The instantaneous and mean velocities data at different Reynolds numbers(Re) were analyzed to provide insights into the velocity distributions in FTIJs. The effect of jet spacing on the stagnation points, instantaneous velocity, mean velocity, profiles of the x- and ycomponents of mean velocity, and turbulent kinetic energy(TKE) distributions of FTIJs were investigated at Re = 4100 with a volumetric flow rate ratio of 0.5. The characteristics of the turbulent flows are similar for all jet spacings tested. Two stagnation points are observed, which are independent of jet spacing and are not located in the center of the flow field. However, velocity and TKE distributions are strongly dependent on the jet spacing.Decreasing jet spacing increases the expansion angle and the values of TKE, leading to strong turbulence, improving momentum transfer and mixing efficiency in FTIJs. The present study shows that optimization of the operating parameters is helpful for designing FTIJs.

Determination of Thermal Properties of Cuts and Residue Streams Obtained in the Molecular Distillation Process

A real-time sensing of the molecular distillation process temperature by a FLUKE brand thermograph Ti50 IR FlexCam and thermography technique was realized. After completion of the molecular distillation, three properties of heat transport chain cuts and residues obtained in the process were estimated by Differential Scanning Calorimetry （DSC） （specific heat, enthalpy, thermal conductivity）. These properties are of great importance for improving oil characterization and for future modeling and simulation of the molecular distillation process. The results show that through the method of Differential Scanning Calorimetry, profiles have been obtained from the variation of specific heat, enthalpy and thermal condutivity as a function of temperature for samples of cuts from the distillation （ASTM D-2892） and fractions of distillate and residue from the process of molecular distillation.

Respiratory Virus Multiplex RT-PCR Assay Sensitivities and Influence Factors in Hospitalized Children with Lower Respiratory Tract Infections

Multiplex RT-PCR assays have been widely used tools for detection and differentiation of a panel of respiratory viral pathogens. In this study, we evaluated the Qiagen ResPlex lI V2.0 kit and explored factors influencing its sensitivity. Nasopharyngeal swab （NPS） specimens were prospectively collected from pediatric inpatients with lower respiratory tract infections at the time of admission in the Shenzhen Children＇s Hospital from May 2009 to April 2010. Total nucleic acids were extracted using the EZ1 system （Qiagen, Germany） and 17 respiratory viruses and genotypes including influenza A virus （FluA）, FluB, parainfluenza virus 1 （PIV1）, PIV2, PIV3, PIV4, respiratory syncytial virus （RSV）, human metapneumovirus （hMPV）, rhinoviruses （RhV）, enteroviruses （EnV）, human bocaviruses （hBoV）, adenoviruses （AdV）, four coronaviruses （229E, OC43, NL63 and HKU1）, and FluA 2009 pandemic H1NI（H1NI-p） were detected and identified by the ResPlex II kit. In parallel, 16 real-time TaqMan quantitative RT-PCR assays were used to quantitatively detect each virus except for RhV. Influenza and parainfluenza viral cultures were also performed. Among the total 438 NPS specimens collected during the study period, one or more viral pathogens were detected in 274 （62.6%） and 201（45.9%） specimens by monoplex TaqMan RT-PCR and multiplex ResPlex, respectively. When results from monoplex PCR or cell culture were used as the reference standard, the multiplex PCR possessed specificities of 92.9-100.0%. The sensitivity of multiplex PCR for PIV3, hMPV, PIV1 and BoV were 73.1%, 70%, 66.7% and 55.6%, respectively, while low sensitivities （11.1%-40.0%） were observed for FluA, EnV, OC43, RSV and H1N1. Among the seven viruses/genotypes detected with higher frequencies, multiplex PCR sensitivities were correlated significantly with viral loads determined by the TaqMan RT-PCR in FluA, H 1N 1-p and RSV （p=0.011-0.000） The Qiagen ResPlex II multiplex RT-PCR kit possesses excellent specificity for simultaneous detection of 17 viral pathogens in NPS specimens in pediatric inpatients at the time of admission. The sensitivity of multiplex RT-PCR was influenced by viral loads, specimen process methods, primer and probe design and amplification condition.

PPP： Towards Parallel Protocol Parsing

Network traffic classification plays an important role and benefits many practical network issues,such as Next-Generation Firewalls(NGFW),Quality of Service(QoS),etc.To face the challenges brought by modern high speed networks,many inspiring solutions have been proposed to enhance traffic classification.However,taking many factual network conditions into consideration,e.g.,diversity of network environment,traffic classification methods based on Deep Inspection(DI) technique still occupy the top spot in actual usage.In this paper,we propose a novel classification system employing Deep Inspection technique,aiming to achieve Parallel Protocol Parsing(PPP).We start with an analytical study of the existing popular DI methods,namely,regular expression based methods and protocol parsing based methods.Motivated by their relative merits,we extend traditional protocol parsers to achieve parallel matching,which is the representative merit of regular expression.We build a prototype system,and evaluation results show that significant improvement has been made comparing to existing open-source solutions in terms of both memory usage and throughput.

A framework for interoperability of BPEL-based workflows

With the prevalence of service-oriented architecture （SOA）, web services have become the dominating technology to construct workflow systems. As a workflow is the composition of a series of interrelated web services which realize its activities, the interoperability of workflows can be treated as the composition of web services. To address it, a framework for interoperability of business process execution language （BPEL）-based workflows is presented, which can perform three phases, that is, transformation, eonformance test and execution. The core components of the framework are proposed, especially how these components promote interoperability. In particular, dynamic binding and re-composition of work-flows in terms of web service testing are presented. Besides, an example of business-to-business （B2B） collaboration is provided to illustrate how to perform composition and conformance test.

Monitoring of coastline changes along the Red Sea,Yemen based on remote sensing technique

The coastline changes along Yemen＇s the Red Sea （Al-muka, Al-khohah, Al-tiaf, Ras Katib and Al- Urji spits） were studied using a series of landsat images （MSS, TM and ETM ＋ , 1972, 1989, 2000, 2006）, coupled with geomorphological, sedimentological and meteorological findings. Comparison of satellite images provided a viable means for establishing long-term coastal changes （accretion and erosion） as observed in the studied spits （Al-Urj, Ras Sham, Ras Maemoon, Ras Katib, Al-Mandar, Nukhaylah, Mujamilah, Ras Ashab Abu-Zahr and Mukha）. The rate of the spit accretion has the greatest value up to 89 pixel/year corresponding to 72 290 m2/year in Mukha, while the spit erosion shows greatest value up to 131 pixel/year corresponding to 106 404 m2/year in Mujamilab. The patterns of accretion and erosion along the spits depend on the spit direction, natural processes mainly of wave-induced longshore currents, the sediments supply and depth of sea.

An Overview of the Advanced Nonintrusive Measurement Techniques in Hypersonic Flow Field

Hypersonic flow-field measurement techniques have been studied for about 50 years. Despite truly remarkable progress with a probe or other device to measure the temperature, pressure or velocity, there are still serious problems for these "intrusive" techniques. The intrusive measurement techniques introduce unexpected shock waves or flow-field structures, even make the boundary layer transition earlier and show a converse result. In recent years, nonintrusive diagnostics have been in urgent demand to give a more accurate and comprehensive flow-field for hypersonic testing. In this paper, an overview of some advanced nonintrusive measurement techniques such as embedded thermocouples for heat flux measurement, Pressure Sensitive Paint(PSP), Particle Image Velocimetry(PIV), infrared thermographs, and focusing Schlieren system are introduced. All of these techniques are nonintrusive and provide measurement of various parameters such as temperature, static pressure, dynamic pressure, flow velocity and visualization of flow structure, which gives us an exact and direct understanding of the hypersonic flow.

Flavor-Changing Bottom-Strange Associated in the Littlest Higgs Model with T-parity at the ILC

In the littlest Higgs model with T-parity(LHT) the mirror quarks induce the special flavor structures and some new flavor-changing couplings,which could greatly enhance the production rates of the flavor-changing processes. We in this paper study some bottom and anti-strange production processes in the LHT model at the International Linear Collider(ILC),i.e.,e^+e^-→bs andγγ→bs.The results show that the production rates of these processes are sizeable for the favorable values of the parameters.Therefore,it is quite possible to test the LHT model or make some constraints on the relevant parameters of the LHT through the detection of these processes at the ILC.

γ-CT Technique Used for Industrial Multiphase Flow Detection

A gamma-ray Computed Tomography （CT）technique based on MATLAB has been developed,and its potential for the application of multiphase flow detection has been demonstrated with simulation results.Aiming to improve the real time performance,we design a CT system with fixed sources and limited detecors.By dissecting the imaging region with Delaunay triangulation method,the algebraic reconstruction algorithm and simultaneous multiplicative algebraic reconstruction algorithm re implemented respective algebraic reconstruction algorithm are implemented respectively to reconstruct cross-sectional images.The resultant images can be utilized to identify flow regimes or extract characteristic parameters.

Use of Non-uniform Rational B-splines for Discharge Calculation in the Velocity Area Method

The velocity area method belongs to the group of primary methods for discharge measurement in hydropower plants. The measurements require an appropriate application of measuring devices and carrying out correctly the process of data analyzing including integration technique. The authors present their own experiences gathered during many years of utilizing the current meter method for discharge measurement in many hydropower plants. They have developed the special integration techniques using the progressive numerical algorithms. The techniques differ from the recommendations contained in the relevant international standards. The authors＇ own software for calculating the discharge from the measured local velocity distribution （obtained using current meters） adopts advanced spline functions, the so-called NURBS （non-uniform rational B-splines）. Nowadays, this kind of splines is commonly used in modeling of the complex geometrical shapes because of their smoothness. It is assessed that it represents much better quality of interpolation than the classic spline functions （classic cubic spline technique）. Particularly, the better properties of the NURBS splines can be observed for velocity profile area characterized by very strong velocity gradients where boundary layers meet the core regions of the flow （mainstream）. In the developed software the boundary layer thickness and exponent of von Karman function is calculated in accordance with the ISO 3354 standard. The software has been successfully used during many performance tests of the hydraulic turbines in Poland for several years. Paper presents the results of flow rate measurements for two different flow systems of Kaplan turbines. First case concerns the application of the current meters in a long circular penstock whereas the second one in short rectangular turbine intake. A comparative analysis of three flow calculation procedures applied for these two cases is presented in the paper-（1） the integration procedure according to the ISO 3354 standard; （2） the integration procedure based on the NS （natural splines）; and （3） the integration procedure based on the NURBS. The results obtained using these three procedures for the first case （intake via long circular penstock） were compared with the results of discharge measurements conducted using the pressure-time method.

Beam Measurement Using Digital Technology

Recently many accelerator parameters are measured by using the digital technology.A data acquisition circuit board adopting software radio technology has been developed.With this circuit board and RF front-end produced i-tech company one can comprise the BPM system.A bunch length monitor composed of the circuit board,power splitter, mix,and band filter has been examined for the bunch length measurement of HLS.The data acquisition circuit board can be further improved,for example,the Ethernet can substitute VME;direct high frequency sampling can substitute medium frequency sampling;using large FPGA.Those will further improve the performance of the data acquisition system,and be the goal of developing this system in the future.

Experimental investigation of the generation of large-amplitude internal solitary wave and its interaction with a submerged slender body

A principle of generating the nonlinear large-amplitude internal wave in a stratified fluid tank with large cross-section is pro- posed according to the ＇jalousie＇ control mode. A new wave-maker based on the principle was manufactured and the experi- ments on the generation and evolution of internal solitary wave were conducted. Both the validity of the new device and ap- plicability range of the KdV-type internal soliton theory were tested. Furthermore, a measurement technique of hydrodynamic load of internal waves was developed. By means of accurately measuring slight variations of internal wave forces exerted on a slender body in the tank, their interaction characteristics were determined. It is shown that through establishing the similarity between the model scale in the stratified fluid tank and the full scale in the numerical simulation the obtained measurement re- suits of internal wave forces are confirmed to be correct.

A single camera volumetric particle image velocimetry and its application

Volumetric particle image velocimetry(VPIV) refers to a PIV-based technique which can obtain full velocity components in a three-dimensional measurement volume.A new VPIV method with a single lens was developed.A three-vision prism was used to make viewing from different angles using one camera.The technique was tested and successfully applied to a three-dimensional three-component(3D3C) measurement of a zero-net-mass-flux jet flow.The accuracy of the measurement was investigated,specifically in steps of calibration,self-calibration and particle triangulation.Time sequence of a vortex ring development was presented.It was shown that the measurement has high accuracy with validation rate of velocity vector reaching about 95%.The flow with vortex ring passing the measurement volume was studied using both swirl strength and vorticity magnitude criteria.Through comparison,the swirl criterion was found to be superior to the criterion of vorticity in differentiating the rotation motion and the free shear.