拉赫玛尼诺夫《C小调第二钢琴协奏曲》

《c小调第二钢琴协奏曲》是拉赫玛尼诺夫的代表作,是他最优秀的作品之一。在这部作品中所体现出来的完整的结构、独具一格的抒情性和钢琴演奏效果的统一,都体现了他对俄罗斯音乐的娴熟掌握。

Evaluation of the slipstream in different regions around a train with respect to different nose lengths:A comparison study

In this work,the flow surrounding the train was obtained using a detached eddy simulation(DES)for slipstream analysis.Two different streamlined nose lengths were investigated:a short nose(4 m)and a long nose(9 m).The time-average slipstream velocity and the time-average slipstream pressure along the car bodies were compared and explained in detail.In addition to the time-averaged values,the _(max)imum velocities and the pressure peak-to-peak values around the two trains were analyzed.The result showed that the nose length affected the slipstream velocity along the entire train length at the lower and upper regions of the side of the train.However,no significant effect was recognized at the middle height of the train along its length,except in the nose region.Moreover,within the train’s side regions(y=2.0-2.5 m and z=2-4 m)and(y=2.5-3.5 m and z=0.2-0.7 m),the ratio of slipstream velocity U_(max) between the short and long nose trains was notably higher.This occurrence also manifested at the train’s upper section,specifically where y=0-2.5 m and z=4.2-5.0 m.Similarly,regarding the ratio of _(max)imum pressure peak-to-peak values Cp-p_(max),significant regions were observed at the train’s side(y=1.8-2.6 m and z=1-4 m)and above the train(y=0-2 m and z=3.9-4.8 m).

拉赫玛尼诺夫《C小调第二钢琴协奏曲》评析

《C小调第二钢琴协奏曲》是拉赫玛尼诺夫的代表作,是他最优秀的作品之一。被誉为是他的"最高杰作",广受世人的喜爱和欢迎。在这部作品完整的结构、独具一格的抒情性和钢琴演奏效果的统一,都体现了他对俄罗斯音乐的娴熟掌握。这首曲子除了在构造上的完满妥善之外,同时还充分发挥了抒情性和钢琴化的效果,并将这些作了绝佳的统一。

Preliminary analysis on the source properties and seismogenic structure of the 2017 M_s7.0 Jiuzhaigou earthquake

At GMT time 13：19, August 8, 2017, an M1.0 earthquake struck the Jiuzhaigou region in Sichuan Province, China, causing severe damages and casualties. To investigate the source properties, seismogenic structures, and seismic hazards, we systematically analyzed the tectonic environment, crustal velocity structure in the source region, source parameters and rupture process, Coulomb failure stress changes, and 3-D features of the rupture plane of the Jiuzhaigou earthquake. Our results indicate the following： （1） The Jiuzhaigou earthquake occurred on an unmarked fault belonging to the transition zone of the east Kunlun fault system and is located northwest of the Huya fault. （2） Both the mainshock and aftershock rupture zones are located in a region where crustal seismic velocity changes dramatically. Southeast to the source region, shear wave velocity at the middle to lower crust is significantly low, but it rapidly increases northeastward and lies close to the background velocity across the rupture fault. （3） The aftershock zone is narrow and distributes along the northwest-southeast trend, and most aftershocks occur within a depth range of 5-20 km. （4） The focal mechanism of the Jiuzhaigou earthquake indicates a left-lateral strike-slip fault, with strike, dip, and rake angles of 152~, 74~ and 8~, respectively. The hypocenter depth measures 20 km, whereas the centroid depth is about 6 kin. The co-seismic rupture mainly concentrates at depths of 3-13 km, with a moment magnitude （Mw） of 6.5. （5） The co-seismic rupture also strengthens the Coulomb failure stress at the two ends of the rupture fault and the east segment of the Tazang fault. Aftershocks relocation results together with geological surveys indicate that the causative fault is a near vertical fault with notable spatial variations： dip angle varies within 660-89~ from northwest to southeast and the average dip angle measures -84~. The results of this work are of fundamental importance for further studies on the source characteristics, tectonic environment, and seismic hazard evaluation of the Jiuzhaigou earthquake.

Physical and numerical modelling of the Severn Barrage

The Severn Estuary has one of the largest tidal ranges in the world and has long been the subject of consideration for tidal energy generation.Whilst plans to build a tidal barrage across the estuary have existed in various forms since the 1920s,the 1989Severn Tidal Power Group(STPG)proposal is commonly referred to as the original Severn Barrage.The UK government abandoned this ebb generation scheme as a public investment project in 2010.However,plans to build a two-way generation scheme were more recently put forward by a private consortium,namely Hafren Power.To assess the impact that a barrage would have on the hydro-environment in the estuary a number of numerical modelling studies have previously been conducted for the STPG scheme.As this design has now been superseded by the Hafren Power proposal,new studies have been conducted to investigate the impact of a two-way scheme.In this study the hydro-environmental impacts of both ebb-only and two-way schemes were assessed using physical and numerical modelling techniques.Scale model barrages were constructed and testing was carried out using a physical model of the Severn Estuary,located in the hydraulics laboratory at Cardiff University.A depth integrated numerical model,namely DIVAST,was applied to the physical model geometry and modifications were made to simulate the effects of the barrage structures.The numerical model predictions showed good agreement with the corresponding laboratory data.The results were consistent with conclusions from previous studies,relating to the ebb-only scheme.These included an increase in the minimum water levels upstream of the barrage,a reduction in the mean water levels downstream of the barrage and a general reduction in tidal velocities.For a two-way scheme changes in the tidal elevations and velocities depended on the exact operating conditions of the barrage.It was found that with no starting head the tidal regime was similar to the natural state,with little change in the elevations and a slight reduction in the mean velocities.As a starting head was introduced there was still little change in elevations downstream of the barrage,however,there was an increase in the minimum water levels upstream of the barrage,and a further reduction in the mean velocities.