变径圆移面过渡段三岔管曲面的计算机辅助几何设计

本文利用由变径圆移面生成理论导出的数学模型，实现了变径圆移面过渡段三岔管曲面的计算机辅助几何设计（ＣＡＧＤ）。

大广坝水电站高窄型圆移曲面尾水管的模板工程

海南省大广坝水电站地下厂房所采用的尾水管的型式为高窄型圆移曲面尾水管。这种新管型在我国二滩水电站和大广坝水电站的设计中第一次使用。二滩为钢里衬管,现在尚未施工;大广坝为钢筋混凝土管。大广坝水电站在尾水管的模板设计中拟定了两种木结构方案,一种称为积木式,另一种称为全断面分节式。本文较详尽地介绍了两种方案的设计、制作、安装过程及注意事项,并对两种方案的优、缺点和适用范围进行了比较。目前,第一套模板已制作完毕。

电动圆移喷灌机作业运行的考查

一、基本情况黑龙江垦区是我国商品粮的重点生产基地之一。现有耕地面积290O多万亩,小麦和大豆的播种面积为2600多万亩,占90％左右。这些作物受自然影响较大,尤其是垦区冬春季降水量少,只占全年降水量的30％左右,且春风大,土壤蒸发快。十年中约有七、八年春旱,严重影响小麦发芽生长。

双面电脑提花移圈圆机及产品开发

介绍双面电脑提花移圈圆机的主要移圈编织原理和编织方法,并结合编织原理对纬编移圈织物的花式结构可能性进行探讨。列举目前几种常见的具有特殊花式结构的纬编移圈产品,包括:移圈罗纹网眼织物、移圈凹凸织物、移圈孔眼织物、移圈提花调线织物等,对它们采用的基本组织和编织手段进行比较分析。给出新型移圈提花面料的设计思路,即采用新型纤维原料,新颖的组织结构,同时结合特殊的后整理手段获得具有高附加值的产品,并采用移圈技术开发了一款新型纬编移圈提花面料,该面料图案美观大方、线条流畅,具有阻燃效果,适合于开发窗帘、台布等装饰用纺织品。

一种适用于全球卫星导航系统的宽带圆极化天线

设计了一款可工作于全球定位系统(GPS)、全球卫星导航系统(GLONASS)、伽利略卫星导航系统及北斗卫星导航系统所有频段的宽带卫星导航天线。天线的辐射体由两对印刷在介质板两侧正交放置的对称振子构成,两对对称振子之间通过圆环形90°移相线连接馈电,从而实现圆极化。同时还设计了带有金属隔离栅的反射腔来改善天线的轴比特性并提高前后比。实测数据与仿真计算比较吻合,天线在所有导航频段范围内S_(11)小于-10 dB,轴比小于2 dB。

水工渐变段设计与计算机图形处理

研究了圆移组合曲面渐变段的几何特性、曲面的设计原理与方法,针对渐变段的定位计算、圆移组合曲面的展开计算作了详细说明.同时,基于AUTOCAD2000的平台,利用VBA作二次开发,开发了渐变段计算机辅助设计与图形处理系统,并将此系统用于某水电站进水口渐变段的设计,绘制出相应的渐变段断面图和组合曲面展开图.通过工程实例证明,该系统有一定的实用性.

C/A码频域多普勒搜索FFT捕获算法

在研究GPS C/A码快速傅里叶变换(FFT)捕获算法的基础上,提出频域多普勒搜索捕获算法,和时域多普勒搜索算法相比,该算法捕获速度提高一倍,甚至更多。针对两个圆移频率分量之间损耗较大问题,提出通过实行不同的下变频,有效解决了损耗问题。MATLAB仿真验证了频域多普勒搜索FFT捕获算法的正确性和频率补偿的有效性。

陀螺飞轮转子的改进全矢动平衡方法及试验

陀螺飞轮转子的动不平衡会造成倾侧运动的抖动现象,降低航天器的指向稳定性与精度。为了实现各向异性下刚性转子偶不平衡辨识,提出一种改进全矢动平衡方法。根据拉格朗日方程建立陀螺飞轮转子动力学模型,使用复数法推导两轴倾侧角间的传递函数,分析陀螺飞轮转子内、外扭杆不等阻尼时两轴响应特性。考虑椭圆轨迹特征矢量相角与不平衡激励相角间的非线性关系,基于能量等效原理并利用椭圆正进动分量构造等效振矢,通过纯试重响应构造移相圆,给出基于等效振矢和移相圆的动平衡算法。在仿真中进行偶不平衡辨识,并在试验平台上完成偶不平衡的校正,数值分析和试验结果证明了所提方法的准确性和有效性。

Design of a Tapered Lens for Semiconductor Laser to Single-Mode Fiber Coupling

The theoretical investigation of the coupling efficiency of a laser diode to a single mode fiber via a hemispherical lens on the tip of the tapered fiber in the presence of possible transverse offset and angular mismatch is reported.Without the misalignment,coupling efficiency increases with the decreasing of taper length.With the misalignment,this relation is that the coupling efficiency decreases with each kind of offset.

Distribution patterns of rock mass displacement in deeply buried areas induced by active fault creep slip at engineering scale

Active fault creep slip induces deformation of rock mass buried deeply in fault zones that significantly affect the operational safety of long linear projects passing through it.Displacement distribution patterns of rock masses in active fault zones which have been investigated previously are the key design basis for such projects.Therefore,a discrete element numerical model with different fault types,slip time,dip angles,and complex geological features was established,and then the creep slip for normal,reverse,and strike-slip faults were simulated to analyze the displacement distribution in the fault rock mass.A disk rotation test system and the corresponding laboratory test method were developed for simulating rock mass displacement induced by creep slippage of faults.A series of rotation tests for softand hard-layered specimens under combined compression and torsional stress were conducted to verify the numerical results and analyze the factors influencing the displacement distribution.An S-shaped displacement distribution independent of fault dip angle was identified corresponding to reverse,normal,and strike-slip faults.The results indicated that the higher the degree of horizontal extrusion,the softer the rock mass at the fault core,and the higher the degree of displacement concentration in the fault core;about 70%of the creep slip displacement occurs within this zone under 100 years of creep slippage.

Dynamic Simulation of Shear-induced Particle Migration in a Two-dimensional Circular Couette Device

The shear-induced migration of neutrally-buoyant non-colloidal circular particles in a two-dimensional circular Couette flow is investigated numerically with a distributed Lagrange multiplier based fictitious domain method.The effects of inertia and volume fraction on the particle migration are examined.The results indicate that inertia has a negative effect on the particle migration.In consistence with the experimental observations,the rapid migration of particles near the inner cylinder at the early stage is observed in the simulation,which is believed to be related to the chain-like clustering of particles.The migration of circular particles in a plane Poiseuille flow is also examined in order to further confirm the effect of such clustering on the particle migration at early stage.There is tendency for the particles in the vicinity of outer cylinder in the Couette device to pack into concentric rings at late stage in case of high particle concentration.

Excited-State Proton Transfer and Decay in Hydrogen-Bonded Oxazole System： MS-CASPT2//CASSCF Study

Herein we have employed high-level multi-reference CASSCF and MS-CASPT2 electronic structure methods to systematically study the photochemical mechanism of intramolecularly hydrogen-bonded 2-（2＇-hydroxyphenyl）-4-methyloxazole. At the CASSCF level, we have optimized minima, conical intersections, minimum-energy reaction paths relevant to the excited-state intramolecular proton transfer （ESIPT）, rotation, photoisomerization, and the excited-state deactivation pathways. The energies of all structures and paths are refined by the MS-CASPT2 method. On the basis of the present results, we found that the ESIPT process in a conformer with the OH... N hydrogen bond is essentially barrierless process; whereas, the ESIPT process is inhibited in the other conformer with the OH... O hydrogen bond. The central single-bond rotation of the S1 enol species is energetically unfavorable due to a large barrier. In addition, the excited-state deactivation of the S1 keto species, as a result of the ultrafast ESIPT, is very efficient because of the existence of two easily-approached keto S1/S0 conical intersections. In stark contrast to the S1 keto species, the decay of the S1 enol species is almostly blocked. The present theoretical study contributes valuable knowledge to the understanding of photochemistry of similar intramolecularly hydrogen-bonded molecular and biological systems.

Numerical Study on Heat Transfer and Flow Characteristics for Laminar Flow in a Circular Tube with Swirl Generators

This study investigated the heat transfer and flow characteristics of one kind of swirlgenerator in a circular heat exchanger tube through a numericalsimulation. The swirlflow induced by this type of swirlgenerator can obtain a high heat transfer rate with minimalpressure drop penalty. The simulations were carried out to understand the physicalbehavior of this kind of mesoscale heat enhancement component. By visualizing the heat transfer and flow characteristics, it is found that the swirlflow is induced by swirlgenerator in the circular tube couples with the impinging jet effect. After passing through the swirlgenerator, the localfriction factor of liquid can quickly return to lower levelmore quickly, while the localNusselt number maintains higher values for a distance; thus, the evaluation criterion of localperformance is improved. Single-factor optimization is used for three geometric parameters, i.e., the angle of swirlgenerator(25o, 45o, and 60o), the length of swirlgenerator(0.005, 0.01, and 0.02 m), and the center rod radius(1, 2, and 3 mm). The optimum parameters of the swirlgenerator for laminar flow of air in a circular tube are obtained, which should be 60o, 0.005 m, and 3 mm, respectively.

Mechanistic Insights into the Photophysics of Ortho-hydroxyl GFP Core Chromophores

Herein we have employed the MS-CASPT2//CASSCF method to study the S1 excited-state intramolecular proton transfers （ESIPTs） of recently synthesized ortho-hydroxyl GFP core chromophores, i.e. OHIM, CHBDI, and MHBID, and their excited-state relaxation pathways. We have found that in OHIM and CHBDI, the ESIPT process is associated with small barriers of 3.4 and 4.2 kcal/mol; while, in MHBDI, it becomes essentially barrierless. Moreover, we have found two main S1 excited-state radiationless channels. In the first one, the enol S1 species decays to the So state via the enol S1/S0 conical intersection after overcoming considerable barriers of 7.0 and 7.7 kcal/mol in OHIM and CHBDI （however, in MHBDI, it is nearly barrierless）. In the second one, the keto S] species is first generated through the ESIPT event; then, it is de-excited into the So state in the vicinity of the keto S1/S0 conical intersection. These energetically allowed excited-state decay channels rationalize ex- perimentally observed ultralow fluorescence quantum yields. The insights gained from the present work may help to guide the design of new ortho-hydroxyl GFP core chromophores with improved fluorescence emission and brightness.

Intrahepatic transplantation of hepatic oval cells for fulminant hepatic failure in rats

AIM： To evaluate the effect of intrahepatic transplantation of hepatic oval cells （HOC） on fulminant hepatic failure （FHF） in rats.METHODS： HOC obtained from rats were labeled with green fluocescent protein （GFP） or 5, 6- carboxyfluorescein diacetate succinmidyl ester （CFDASE）. Cell fluorescence was observed under fluorescent microscope at 6, 24, 48 and 72 h after labeling. CFDA- SE labeled HOC （5 × 10^6 cells each rat） were injected into livers of rats with FHF induced by D-galactosamine. Serum albumin （ALB）, alanine aminotransferase （ALT）, aspartate aminotransferase （AST） and total bilirubin （TBil） levels were measured at different time points. Liver function of rats was examined on days 3, 7, 14 and 21 after HOC transplantation.RESULTS： The positive rate of GFP and CFDA-SE labeled HOC was 10% and 90%, respectively, with no significant change in cell viabilities. The survival rate was higher in HOC transplantation group than in control group, especially 48 （9/15 vs 6/15） and 72 h （9/15 vs 4/15） after HOC transplantation. The serum ALT, AST and TBil levels were decreased while the serum AIb level was increased after HOC transplantation. Fluorescence became faded and diffused in liver tissues, suggesting that proliferation and differentiation occur in transplanted HOC.CONCLUSION： CFDA-SE is superior to GFP in labeling HOC, although fluorescence intensity is decreased progressively with cell division. HOC transplantation can improve the liver function and increase the survival rate of recipients.

Surgical experience in splitting donor liver into left lateral and right extended lobes

AIM： To outline the surgical experience with donor liver splitting in split liver transplantation.METHODS： From March 1 to September 1 in 2004, 10 donor livers were split ex situ into a left lateral lobe （segments Ⅱ and Ⅲ） and a right extended lobe （segments Ⅰ, Ⅳ-Ⅷ） in Medical School of Hannover, and thereafter split liver transplantation was performed successfully in 29 cases. The average age, weight and ICU slaying period of the donors were 32.7 years （25-52 years）, 64.5 kg（45-75 kg） and 2.4 d （2-8 d） respectively.RESULTS： The average weight of the whole graft and the left lateral lobe was 2 322.6 g （956-2 665 g） and 282.8 g （298-373 g） respectively, and the average ratio of left lateral lobe to the whole graft was 0.225 （0.278-0.274）.The average graft to recipient weight ratio （GRWR） of the left lateral lobe and the right extended lobe reached 2.44% （2.22-5.42%） and 2.73% （2.32-2.30%） respectively.On average it took approximately 205 min （85-235 rain）to split the donor liver. Five donor organs showed anatomic variation including the left hepatic vein variation in two cases, the left hepatic artery variation in two cases and the bile duct variation in one case.CONCLUSION： Split liver transplantation has become a mature surgical technique to expand the donor pool with promising results. In the process of graft splitting, close attention needs to be paid to potential anatomic variations,especially to variations of the left hepatic vein, the left hepatic artery, and the bile duct.

Nosing process of empty and foam-filled circular metal tubes on semispherical die by theoretical and experimental investigations

Nosing process of circular metal tubes in empty and polyurethane foam-filled conditions on a semispherical rigid die was analyzed by theoretical and experimental methods.A new theoretical model of plastic deformation of circular metal tubes was demonstrated during the nosing process on a rigid semispherical die.Based on the analytical model,some theoretical relations were calculated to estimate instantaneous forming load and dissipated energy of empty and foam-filled circular metal tubes versus axial displacement.Some circular brazen and aluminum tubes were prepared and shaped into semispherical nosed nozzles to verify the present theory.Comparison of theoretical predictions and the corresponding experimental measurements reveals that predicted load?displacement and dissipated energy?displacement diagrams by theoretical formulas have a good correlation with the corresponding experimental curves and it proves verity of the theory.Also,the present theory shows that dissipated energy and axial load of empty tubes depend on material type,wall thickness and diameter of the tubes and they are independent of tube initial length.Furthermore,the experimental results show that the presence of polyethylene Teflon-constraints increases ultimate axial displacement of the forming process.

MHD mixed convective stagnation-point flow of Eyring-Powell nanofluid over stretching cylinder with thermal slip conditions

The optimal design of heating and cooling systems must take into account heat radiation which is a non-linear process.In this study,the mixed convection in a radiative magnetohydrodynamic Eyring-Powell copperwater nanofluid over a stretching cylinder was investigated.The energy balance is modeled,taking into account the non-linear thermal radiation and a thermal slip condition.The effects of the embedded flow parameters on the fluid properties,as well as on the skin friction coefficient and heat transfer rate,are analyzed.Unlike in many existing studies,the recent spectral quasi-linearization method is used to solve the coupled nonlinear boundary-value problem.The computational result shows that increasing the nanoparticle volume fraction,thermal radiation parameter and heat generation parameter enhances temperature profile.We found that the velocity slip parameter and the fluid material parameter enhance the skin friction.A comparison of the current numerical results with existing literature for some limiting cases shows excellent agreement.

Password-Authenticated Multiple Key Exchange Protocol for Mobile Applications

To achieve privacy and authentication sinmltaneously in mobile applications, various Three-party Password-authenticated key exchange （3PAKE） protocols have been proposed. However, some of these protocols are vulnerable to conventional attacks or have low efficiency so that they cannot be applied to mobile applications. In this paper, we proposed a password-authenticated multiple key exchange protocol for mobile applications using elliptic curve cryptosystem. The proposed protocol can achieve efficiency, reliability, flexibility and scalability at the same time. Compared with related works, the proposed protocol is more suitable and practical for mobile applications.

Dark energy and fate of the Universe

We explore the ultimate fate of the Universe by using a divergence-free parametrization for dark energy w（z）=w0＋wa, [In（2 ＋ z） / （1 ＋ z） - In 2] . Unlike the Chevallier-Polarski-Linder parametrization, this parametrization has well behaved, bounded behavior for both high redshifts and negative redshifts, and thus can genuinely cover many theoretical dark energy models. Alter constraining the parameter space of this parametrization by using the current cosmological observations, we find that, at the 95.4% confidence level, our Universe can still exist at least 16.7 Gyr before it ends in a big rip. Moreover, for the phantom energy dominated Universe, we find that a gravitationally bound system will be destroyed at a time t = P√2｜ 1 ＋ 3w（ 1）] / [6π] 1 ＋ w（-1）｜], where P is the period of a circular orbit around this system, before the big rip.