TURBULENT SEPARATED REATTACHED FLOW IN A TWO-DIMENSIONAL CURVED-WALL DIFFUSER

A turbulent separation-rcattachment flow in a two-dimensional asymmetrical curved-wall diffuser is studied by a two-dimensional laser doppler velocimeter.The turbulent boundary layer separates on the lower curved wall under strong pressure gradient and then reattaches on a parallel channel.At the inlet of the diffuser,Reynolds number based on the diffuser height is 1.2×10~5 and the velocity is 25.2m/s.The re- sults of experiments are presented and analyzed in new defined streamline-aligned coordinates.The experiment shows that after Transitory Detachment Reynolds shear stress is negative in the near-wall backflow region. Their characteristics are approximately the same as in simple turbulent shear layers near the maximum Reynolds shear stress.A scale is formed using the maximum Reynolds shear stresses.It is found that a Reynolds shear stress similarity exists from separation to reattachment and the Schofield-Perry velocity law ex- ists in the forward shear flow.Both profiles are used in the experimental work that leads to the design of a new eddy-viscosity model.The length scale is taken from that developed by Schofield and Perry.The composite velocity scale is formed by the maximum Reynolds shear stress and the Schofield Perry velocity scale as well as the edge velocity of the boundary layer.The results of these experiments are presented in this paper

State-to-state Photoionization Dynamics of Vanadium Nitride by Two-color Laser Photoionization and Photoelectron Methods

We have conducted a two-color visible-ultraviolet （VIS-UV） resonance-enhanced laser pho- toionization and pulsed field ionization-photoelectron （PFI-PE） study of gaseous vana- dium mononitride （VN） in the total energy range of 56900-59020 cm-1. The VN molecules were selectively excited to single rotational levels of the intermediate VN（D3H0, v＇=0） state by using a VIS dye laser prior to photoionization by employing a UV laser. This two-color scheme allows the measurements of rovibronically selected and re- solved PFI-PE spectra for the VN＋（X2A; v＋=0, 1, and 2） ion vibrational bands. By simulating the rotationally resolved PFI-PE spectra, J＋=3/2 is determined to be the lowest rotational level of the ground electronic state, indicating that the symmetry of the ground VN＋ electronic state is 2A3/2. The analysis of the PFI-PE spectra for VN＋ also yields accurate values for the adiabatic ionization energy for the formation of VN＋（X2A3/2）, IE（VN）=56909.5＋0.8 cm-1 （7.05588±0.00010 eV）, the vibrational fre- quency wc＋=1068.0±0.8 cm-1, the anharmonicity constant wc＋Xe＋=5.8±0.8 cm-1, the rotational constants Be＋=0.6563±0.0005 cm-1 and ae＋=0.0069±0.0004 cm-1, and the equi-librium bond length, re＋=1.529A, for VN＋（X2A3/2）; along with the rotational constants Bc＋=0.6578i0.0028 cm-1 and a＋=0.0085±0.0028 cm-1, and the equilibrium bond length re＋=1.527A for VN＋（X2As/2）, and the spin-orbit coupling constant A=153.3±0.8 cm-1 for VN＋（X2/k5/2,3/2）. The highly precise energetic and spectroscopic data obtained in the present study are valuable for benchmarking the predictions based on state-of-the-art ab initio quantum calculations.

论杜波依斯的“双重意识”及其对美国黑人文学的影响

通过对杜波依斯的介绍及其“双重意识”概念的解释,阐述了美国黑人的内在心理冲突问题和困惑所在。指出杜波依斯“双重意识”的概念是欧洲浪漫主义和美国超验主义的产物,从象征意义和比喻意义两方面讨论了“双重意识”的内涵。指出“双重意识”揭示了黑人性格的二重性和黑人作家的两难抉择。分析了黑人文学作品中出现同化和分离之间的持续张力的原因,强调了杜波依斯提出的“双重意识”的重要作用。

Separation and Identification of Differentially Expressed Proteins in Pistillate Flowers between Different Mulberry Cultivars

[Objective] This study aimed to explore the proteins related to pistillate flower development in different mulberry cultivars. [Method] The total proteins of the pistillate flowers of two mulberry cultivars Dal0 （Morus atropurpurea Roxb.） and SG01 （Morus muIticaulis Perr.） were extracted, separated and detected through two- dimensional electrophoresis （2-DE） and mass spectrometry. [Result] There was sig- nificant difference in the expression of proteins from the pistillate flowers of different mulberry cultivars. From the 2-DE images of Dal0 and SG01, 445_＋17 and 425_＋12 protein spots were respectively detected. The expression levels of 75 protein spots differed significantly. Thirteen spots those were expressed at high levels and well separated were analyzed by mass spectrometry, and nine of them were identified successfully. The nine proteins are involved in the glycometabolism, protein and amino acid metabolism and defense responses during the development of mulberry pistillate flower after they were pollinated. [Conclusion] The findings will provide reference for further study on the molecular mechanism of mulberry pistillate flower de- velopment.

按灵敏度与传递函数设计的二自由度控制方法

根据灵敏度函数的概念，利用模型参考自适应的原理，提出了按系统灵敏度函数与系统传递函数独立设计的二自由度控制方案。论证了二自由度控制原理，并推导了实现这一控制的条件，理论研究和实验结果表明，将这一控制思想运用于参数大范围变化的控制系统设计时，能极大增强系统的鲁棒性。

层间储液的双层圆柱壳水弹性振动

本文对层间储有液体的双层圆柱厚壳水弹性振动进行了详细的分析。重点研究计算了双层圆柱厚壳考虑剪切影响的刚度阵、质量阵及其水弹性动力特性,给出动水压力分布规律和任意动载荷下的动位移响应。文后附有算例,证明了本文方法的正确性和合理性。

一类奇异边值问题的正解

考虑如下二阶非线性奇异两点边值问题{-u''+f(u)-u^(-γ)=λu,0<x<1,u>0,u(0)=u(1)=0,}其中0<γ<1为常数,λ>0为特征值参数.f(u)满足给定的条件.利用上下解方法和Arzela-Ascoli定理讨论二阶非线性奇异两点边值问题正解的存在性和唯一性.特别地,利用适当的变换和最大值原理给出方程在特殊形式下正解的渐近行为.

针对发动机平面度的二维FusedLASSO多元统计控制图

针对具有二维平面自然顺序关系的多元数据,提出了一种基于二维Fused LASSO回归模型的多元统计过程控制图。由于二维Fused LASSO多元回归模型对相邻系数的差异进行惩罚,因此它对检测出变量间的自然顺序关系非常有效。通过数值仿真实验可以看到,二维Fused LASSO控制图能更加快速有效地检测出具有二维平面自然顺序的多元过程中均值发生的变化,且在偏移量越大的情况下优势更加明显。最后通过对发动机平面度数据的实例验证,给出了二维Fused LASSO控制图的步骤和适用性。

声触诊弹性成像与二维剪切波弹性成像检测肝脏硬度的比较

【目的】将声触诊弹性成像(STE)和二维剪切波弹性成像(2D-SWE)检测肝脏硬度进行比较,为STE新技术的临床应用提供循证依据。【方法】采用STE和2D-SWE技术,对43例健康志愿者和63例肝硬化患者行肝硬度检测,对比分析两种技术的检测成功率、操作者内重复性、测值相关性和测值差异。【结果】肝脏STE、2D-SWE检测成功率分别为100%(106/106)、96.2%(102/106)(χ^2=2.320,P=0.128),4例2D-SWE检测失败的均为肝硬化患者。在健康组STE测值高于2D-SWE[5.83(5.30~6.37)kPa vs 5.00(4.80~5.20)kPa,Z=4.419,P<0.001]、肝硬化组低于2D-SWE[15.82(11.71~25.02)kPa vs 18.50(11.95~29.93)kPa,Z=-2.981,P=0.003]。STE和2D-SWE两种技术的测值相关系数为0.896(95%CI:0.849~0.928,P<0.001)。【结论】STE检测成功率高、重复性好,尤其在肝硬化患者穿透性好、与2D-SWE比较更具优势;STE测值与2D-SWE不直接等同,临床应用中需要注意。

A General Purpose Analysis Package

This paper presents a general-purpose analysis package able to solve two- and three- dimensional analysis problems. The system can use the following methods of solution: Successive Approximation (SA), Optimal Interpolation (OI), and 3D-Var. Analyses are given for the following parameters: zonal and meridional wind components, temperature, relative humidity, and geopotential height. The analysis package was applied to produce analyses at 6 h time interval for the period 1-11 August 2008. The period was selected for data availability and forty-one analyses were collected. The results show the validity of the different solutions, which can be chosen depending on the physical problem to solve and on the computational resources available. In particular, assuming the observations as the reference, all solutions show a decrease of the RMSE compared to the background. The decrease is consistent with the particular setting of the analysis system used in this paper. The comparison between different solutions shows that the SA converges to OI in few iterations, and that the SA solution with ten iteration is, in practice, equal to OI. Moreover, the 3D-Var method shows its potential to improve the analysis, once the horizontal and vertical length-scales and the background and observational errors are set optimally, because its solution may be sizeably different from two-dimensional methods.

Rotating Stall and Stall-Controlled Performance of a Single Stage Subsonic Axial Compressor

Activities by various authors on aerodynamics and control dynamics of rotating stall in axial compressor are first traced. Then, a process of stall cell evolution in a subsonic stage is discussed based on a 2-D CFD. A few numbers of vortices grow ahead of the rotor accumulating vorticity ejected from lightly stalled blades, and eventually organize a cell of circumferentially aligned huge vortices, which merge and recess repeatedly during the rotation. Such stall disturbance is intensified on trailing side of a circumferential inlet distortion and decays on the leading side. Considering these features, a new algorithm for stall warning is developed based on a correlation between pressure waveforms at each passing of a fixed blade. A remarkable change in the correlation level at near-stall provides a warning signal prior to the stall onset with sufficiently large time margin. This scheme is applied to achieve rotating stall prevention by actuating flaps installed on the hub. The last issue is on characteristics of forward swept blade which has much increased throttle margin with decreased tip loss. A 3-D computation shows that a secondary vortex generated in suction surface mid span interacts to reduce the tip leakage vortex that initiates the stall.

A coincidence experimental setup for investigating multiple electron processes

The coincidence experimental setup for studying multiple electron processes at low energies established at the Institute of Modern Physics was presented. The setup includes time-of-flight spectrometer, position sensitive detector, and multi-parameter data acquisition system. Presented were a TOF spectrum for Ar 12+ on Ar collisions, a position spectrum obtained in O 2++He collisions, and a two-dimension spectrum for Ar 8++Ar collisions at 104 keV. The experimental results were analyzed in detail and 12 subprocesses were identified from the two-dimension spectrum.

ANALYSES OF LOCATION-PRICE GAME ON NETWORKS WITH STOCHASTIC CUSTOMER BEHAVIOR AND ITS HEURISTIC ALGORITHM

In this paper,a two-stage model is developed to investigate the location strategy andthe commodity pricing strategy for a retail firm that wants to enter a spatial market with multiplecompetitive facilities,where a competitor firm is already operating as a monopoly with several outlets.Expected market shares are calculated based on the stochastic customer behavior on networks.Theauthors provide a sufficient condition for the existence of equilibrium prices in the price game for thefirst time.The existence and uniqueness of the pure strategy Nash equilibrium price with a specifiedutility function are proved in the subgame.A metaheuristic based on tabu search is proposed tosearch the optimal location-price solution of the model.In addition,the authors provide two numericalexamples to illustrate how to obtain the optimal solution and conduct sensitivity analysis.The analysisshows that the best location decision is robust for the follower firm,price game is more intense whenincomes of consumers are lower or there are more substitution products,and neither chain retail gainsfrom the price competition.

Integrating surface and interface engineering to improve optoelectronic performance and environmental stability of MXenebased heterojunction towards broadband photodetection

Two-/three-dimensional(2D/3D)heterojunction-based photodetectors have attracted much attention due to their highly efficient photoelectric conversion driven by the built-in electric field for high-speed photoresponse.However,a large dark current induced by unexpected surface states at the interface between 2D materials and 3D bulks is widely observed in such structures,greatly degrading their optoelectronic performance.Herein,a heterojunction of proton acid HCl treated MXene(H-MXene)/TiO_(2)/Si via integrating surface and interface engineering is fabricated,which exhibits decreased dark current and improved environmental stability.A feasible strategy to optimize the interface properties between MXene and Si is proposed by an in-situ oxidation process of MXene into TiO_(2),resulting in a suppressed dark current as well as high specific detectivity.Benefitting from the enhanced light absorption of MXene on the bulk Si substrate,the photoresponse of as-fabricated devices in the near-infrared region is also elevated.Moreover,the treatment of proton acid HCl on the surface of MXene brings better conductivity and environmental stability due to the decreased layer spacing of MXene,which is further confirmed by both experimental and theoretical methods.This work opens a unique way to comprehensively boost the optoelectronic performance of MXene-based photodetectors.

On the Intersection of Binary Linear Codes

For a binary linear code,a new relation between the intersection and(2,2)-separating property is addressed,and a relation between the intersection and the trellis complexity is also given.Using above relations,the authors will apply several classes of binary codes to secret sharing scheme and determine their trellis complexity and separating properties.The authors also present the properties of the intersection of certain kinds of two-weight binary codes.By using the concept of value function,the intersecting properties of general binary codes are described.