平行载流直导线相互作用演示器的制作

以往的平行载流直导线间相互作用演示方案中,直导线灵活性差及电流过大(10～30 A)等问题没能很好解决,使得实际教学中该演示难以进行。为此,笔者在指导学生制作教具时设计制作了一种新型演示器。

混合治理视角下PPP项目政企治理水平对项目绩效的影响研究

PPP模式以其在公共服务供给领域的巨大优势被广泛应用于基础设施建设中,然而目前我国在PPP项目实践过程中仍存在许多困局,尤其是多主体参与管理的混合治理局面对PPP项目绩效的影响路径有待解析和完善。研究从混合治理视角揭示了政企治理水平对PPP项目绩效的作用机制,在此基础上运用结构方程模型对理论模型进行实证检验。结果表明:政企混合治理水平对项目绩效存在显著的正向影响;同时,合作风险感知与合作行为在治理水平对项目绩效的影响过程中发挥平行中介作用。

Nonlinear wave-wave interactions and wedge waves

A tetrad mechanism for exciting long waves, for example edge waves, is described based on nonlinear resonant wave-wave interactions. In this mechanism, resonant interactions pass energy to an edge wave, from the three participating gravity waves. The estimated action flux into the edge wave can be orders of magni- tude greater than the transfer fluxes derived from other competing mechanisms, such as triad interactions. More- over, the numerical results show that the actual transfer rates into the edge wave from the three participating gravity waves are two- to three- orders of magnitude greater than bottom friction.

Dynamic Interaction of Parallel Moving Ships in Close Proximity

Nowadays,there are many studies conducted in the field of marine hydrodynamics which focus on two vessels traveling and floating in sufficiently close proximity to experience significant interactions.The hydrodynamic behavior of parallel moving ships in waves is an interesting and important topic of late.A numerical investigation has been carried out for the prediction of wave exciting forces and motion responses of parallel moving ships in regular waves.The numerical solution was based on 3D distribution technique and using the linear wave theory to determine the exciting forces and ship＇s motion.The speed effects have been considered in the Green function for more realistic results.The numerical computations of wave exciting forces and motion responses were carried out for a Mariner and Series 60 for the purpose of discovering different Froude numbers and different separation distances in head sea conditions.Based on the numerical computations,it was revealed that the sway,roll and yaw have a significant effect due to hydrodynamic interaction.

Study on the Flow Field around Two Parallel Moving Bubbles and Interaction Between Bubbles Rising in CMC Solutions by PIV

The flow fields surrounding two parallel moving bubbles rising from two identical orifices submerged in non-Newtonian fluid of carboxymethylcellulose （CMC） solution of three different mass concentration were measured experimentally by the use of particle image velocimetry （PIV）. The influences of gas flowrate, solution mass concentration, orifice interval and the angle between two bubble centers line and vertical direction on the flow field surrounding bubbles were discussed respectively by analyzing the velocity vector, velocity contours as well as individual velocity components. The results show that the liquid velocity both in front of two bubbles and behind increases with gas flowrate duo to shear-thinning effect of previous bubbles, whereas decreases with the increase of CMC concentration due to the increase of drag force acting on bubbles. The effect of the orifice interval on the flow field around two moving bubbles becomes gradually obvious as the interval becomes closer. Moreover, two adjacent side-by-side bubbles repulse each other during rising, leading to the practical interval between them increased somewhat above the orifice interval. When the distance between bubbles is less than the orifice interval 10 mm, the interaction between two neighboring bubbles changed from mutual repellence to attraction with the decrease of the angle of the line of linking two bubble centers to the vertical direction.

Synthesis, Crystal Structure and Interactions with Different G-quadruplex DNA and ctDNA of Zn-CAP

In this study, one mononuclear zinc（II） complex with 1,2-bis CAP （（5-chlorosalicylidene amino）-phenylene）： C22C13N2035Znl5 H0125 （Zn-CAP） was synthesized. The binding properties of Zn-CAP with G-quadruplex DNA and ctDNA （calf thymus DNA） were examined by fluorescence, CD （circular dichroism） spectroscopic and FRET （fluorescence resonance energy transfer） assay. In the fluorescence emission spectral analysis, the addition of three series of G-quadruplex DNA （G4-HTG21, G4-Pu27 and G4-c-kit-l） into the Zn-CAP solution induced moderate or add hypochromicity with total quenching ratios of 10.73%, 15.07% and 8.59% in the presence of K＋ were achieved, respectively. While the addition of ctDNA under same condition only caused 7.08% quenching on the fluorescence emission of Zn-CAP. In the CD spectral analysis, the interaction with Zn-CAP could induce significant spectral changes on the CD absorption of G4-HTG21, G4-Pu27 and G4-c-kit-1, with 106.00%, 93.06%, 113.47% increment at 232 nm absorption, along with a 81.11%, 92.80%, 83.72% decrement at 295 nm or 270 nm absorption, which demonstrated that the antiparallel structure of G-quadruplex DNA is more stable in the presence of Zn-CAP. Comparatively, the addition of Zn-CAP could induce significant spectral changes on the CD absorption of double helix ctDNA, with 64.17% decrement on the positive peak absorption, along with a 90.91% increment on the negative peak absorption. On the other hand, in the FRET-melting assay analysis, it was clear that Zn-CAP at 0.5 equivalences could raise the melting temperature of G-quadruplex （F2 IT or FPul 8T） by 3.45℃ and 15.85℃, indicating an obvious stabilization effect of Zn-CAP on G-quadruplex in Pu27. All the results indicated that Zn-CAP exhibited higher binding affinity and binding intensity to G-quadruplex DNA than ctDNA, especially G-quadruplex Pu27.

Quasi-stationary planetary wave-mean flow interactions in the Northern Hemisphere stratosphere and their responses to ENSO events

Based on the ERA-40 reanalysis data from the European Centre for Medium-Range Weather Forecasts and the output of ECHAM5/MPI-OM, this study investigated the interactions between the quasi-stationary planetary wave （SPW） and mean flow, and their responses to E1 Nifio-Southern Oscillation （ENSO） events in the northern hemispheric stratosphere. Results show that the activity of SPW is the strongest in winter, when the SPW propagates along the polar waveguide into the stratosphere and along the low-latitude waveguide to the subtropical tropopause. The analysis of three dimensional SPW structure indicates that the main sources of SPW activity are located over the Eurasian continent and the North Pacific north of 45°N. On the one hand, the two waveguides of the SPW reflect the influence of mean flow on the propagation of the SPW. On the other hand, the upward propagating SPW can interact with the stratospheric mean flow, leading to deceleration of the zonal mean westerly. Furthermore, the SPW exhibits clear responses to ENSO events. During E1 Nifio winters, the SPW in the strat- osphere tends to propagate more upward and poleward. Its interactions with mean flow can induce a dipole pattern in zonal mean zonal winds, with accelerated westerly winds at low-middle latitudes and decelerated westerly winds at high latitudes. The ECHAM5/MPI-OM model reproduces the climatology of the SPW well. Although the simulated SPW is slightly weaker than the observations in the stratosphere, the model＇s performance has significant improvements compared with other GCMs used in previous studies. However, there are still some problems in the responses of the SPW to ENSO in the model. Although the model reproduces the responses of both the amplitude and the SPW-mean flow interactions to ENSO well in the troposphere, the stratospheric responses are quite weak. Therefore, further studies are needed to improve the simulation of the stratospheric atmospheric circulation and related dynamical processes.