高速列车盘形制动器热-结构耦合方法研究

盘形制动器热负荷计算是高速列车制动盘研发设计的关键环节,其计算结果是列车运行参数配置的依据.开发合适的计算方法建立计算精度高、工况适用性广的热-结构耦合计算模型是盘形制动器热负荷计算的关键问题.针对动车组用轴装制动盘制动过程,充分考虑制动闸片和制动盘的几何特性、运动特性和载荷工况,提出位移梯度循环法,基于ABAQUS软件建立盘形制动器摩擦副三维瞬态传热有限元模型,运用位移梯度循环法推导出热流加载式,用以计算制动过程中产生的摩擦热流,解决摩擦作用沿制动盘周向差异造成的耦合结果偏差.运用位移梯度循环法对制动盘进行热-结构耦合分析,并将仿真结果与试验数据、现场调研成果进行对比,通过仿真与试验结果的峰值温度误差率、相关性系数等统计学指标及现场调研观测结果评定该模型的计算精度及工况适用性.研究结果表明:基于位移梯度循环法的热-结构耦合模型可有效模拟制动盘在制动过程中温度变化规律且具有良好的重复性与稳定性,结构场分析出的制动盘热裂纹失效易发位置与该型号制动盘装车运用情况相符.研究成果可有效模拟高速列车在制动时制动盘的热-结构耦合过程,尤其在大轴重下的持续制动或间隔制动工况下,制动时间越长,计算精度越高.     

一种无环流数字控制STS模块的研制

分析了静态转换开关（STS）的无环流切换控制的工作原理。针对其中关键的电流状态检测问题,提出了一种根据晶闸管门极电压来检测晶闸管导通状态的方案。设计了1个TMS320LF2406控制的12A静态转换开关模块,描述了DSP中电压掉电时的控制时序,实际测试表明模块断电时间小于规定时间,提出的电流检测方法正确。     

铁路数据流通路径及内部共享激励值计算模型研究

随着数字化转型的不断深入,铁路领域积累了大量相关专业数据。在铁路数据要素化过程中,亟需通过多方数据流通路径实现跨部门、跨行业的共享,最大化地挖掘和释放数据要素价值。文章在分析国内外数据流通相关政策基础上,结合铁路数据需求提出内部共享交换和外部流通交易等差异化数据流通路径,并提出基于成本法的铁路内部共享激励值计算模型,选取铁路某系统数据进行实例计算,为促进铁路数据流通提供思路。     

Winter intensification and water mass evolution from yearlong current meters in the Northeast Water Polynya

In the summer of 1992, four current meter moorings were deployed in and later retrieved from the Northeast Water (NEW) polynya on the East Greenland Shelf by the USCGC Polar Sea. The moorings provided hourly temperature, salinity and current data for approximately one year. In the NEW, the circulation intensified and steadiness increased during winter. This intensification was most readily observed at 150 m on the southern side of Westwind trough. The surface layer freshened from summer through December due to ice-melt and freshwater runoff mixing down to at least 75 m. From December through early spring, salinity increased probably due to brine rejected during ice formation. Wintertime events showed water at 75 m with temperatures at the freezing point. Knee Water (KW) was not observed in the current meter data. However, a warmer and fresher than KW watermass was observed at 150 m over the shelf and may result from mixing outside the NEW among KW and the major water masses influencing the region. Polar Water and Atlantic Intermediate Water. Several short-lived events of 3 to 7 days duration perturbed the T-S character at each of the current meters. We believe that these T-S shifts were anticyclonic eddies advecting through the NEW polynya. During such perturbations, T-S values found generally at 75 m were observed at 150 m and T-S values generally at 150 m were observed at 250 m. On the northern side of the Westwind trough, the current meter data provided direct evidence for westward flow into the western extent of the trough at a depth of 250 m. This southwesterly current along the northwest slope of the trough at 250 m is in agreement with the summertime ADCP measurements made in 1992 aboard Polar Sea, and is consistent with the flow inferred from summer hydrography measured from Polarstern in 1993.     

自然循环转强迫循环时反应堆功率瞬态特性研究

采用一套完整的仿真分析系统,研究了船用核动力装置一回路自然循环向强迫循环过渡时反应堆功率变化的瞬态特性.计算结果表明,初始反应堆功率水平对过渡过程有着重要的影响,较高的初始功率水平有可能威胁反应堆的安全.针对过渡过程中的潜在风险,提出了手动下插控制棒的人为干预措施.分析结果表明,该干预措施可以有效地改善过渡过程的安全性.     

全流通下的财务报告与信息披露

我国资本市场股权分置改革基本完成。这就要求上市公司在全流通后的财务报告及信息披露将更为完善。本文分析了目前我国上市公司的财务报告及信息披露存在的问题,对规范上市公司会计信息披露提出了对策:上市公司不仅需要提供公司的财务信息,而且需要提供公司治理、内部控制、风险控制、社会责任等相关情况,并从企业内部监管、法律监管、社会监管等方面规范上市公司的会计信息披露。     

The use of digital filter initialization to diagnose the mesoscale circulation and vertical motion in the California coastal transition zone

A dynamical method of initializing the primitive equations is tested and used to diagnose the three-dimensional circulation associated with jets and eddies as found in the California coastal transition zone (CTZ). The initialization method, referred to as digital filter initialization (DFI), was recently developed by [Monthly Weather Review 120 (1992) 1019] for use in an intermittent data assimilation system in the atmosphere. The ability of DFI to recover the mesoscale ageostrophic circulation associated with finite amplitude jets and eddies in the ocean is first demonstrated using control data produced by simulations with a primitive equation model. The DFI method is then applied to synoptic hydrographic data collected during several California CTZ surveys in the summer of 1988. The diagnostic results indicate the existence of jets, eddies, and filaments in the CTZ domain with maximum horizontal currents of the order of 0.6 m/s at the surface. Currents associated with such jets and filaments are coherent to a depth of over 500 m. The surface currents associated with a prominent cool filament are generally confluent, and weakly convergent on average, along the 270 km offshore extent of the filament. Meanders in the jet display convergence and downwelling upstream of pressure troughs and divergence and upwelling downstream of the troughs. Maximum vertical velocities at 100 m are of the order of 10 m/day. This result is consistent with independent estimates of subduction rates made from biological studies in this and similar coastal filaments in the CTZ program.     

Water masses and cyclonic circulation in Bay of La Paz, Gulf of California, during June 1998

The Bay of La Paz, a coastal and shallow basin of the Gulf of California (depth<420 m), exchanges mixed-layer waters with the Gulf of California predominantly through Boca Grande (Big Mouth), in the northeastern part of the bay. Equatorial Surface Water (ESW) flows from the gulf to the bay; once there, due to evaporation processes, this water increases its salinity above 35.00, therefore becoming Gulf of California Water (GCW) Mass. During June 1998, the baroclinic circulation in the bay was dominated by a cyclonic gyre. The hydrographic dome, related to this gyre, is depicted until approximately 150-m depth. However, the vertical mixing of water between the mixed-layer and the ones below practically does not occur because of the development of a sharp pycnocline. This fact and the isolation of the bottom of the bay by a bathymetric sill (approximately 250-m depth) at Boca Grande induce low oxygen content, particularly in the bottom-waters (O₂<0.1 ml/l). Chlorophyll values are higher and with larger vertical fluctuations within the Bay of La Paz than outside.     

Cross-shelf circulation and phytoplankton distribution at the summertime New England shelfbreak front

We investigate aspects of the secondary (cross-shelf) circulation at the Middle Atlantic Bight shelfbreak front using high-resolution data collected on the New England Shelf in August 2002. The alongshore shelfbreak jet coincides with the front at the seaward edge of the cold pool (remnant winter shelf water) and there is a suggestion of a cross-stream convergence centered at the jet core. Despite indications of convergence we found no evidence of a surface subduction on the seaward side of the front. At depth 70 m near the shelfbreak there was a patch of chlorophyll, located within a local temperature–salinity maximum which, though significantly below the euphotic zone, appeared to be photo-acclimated and viable. The chlorophyll feature could be the result of a local subduction by a larger scale eddy circulation seaward of the front.Dye tracer experiments directly observed the convergence at the foot of the shelfbreak front and subsequent upwelling of bottom boundary layer water along the shoreward side of the shelfbreak front. But, we found no evidence that this upwelling influenced productivity at the front. Further, since there was no cross-shelf maximum in subsurface chlorophyll at the front, we conclude that this productivity is in general, sustained by a broadly distributed local vertical nutrient flux from an underlying nutrient reservoir.     

桨后整流支架的设计方法

简要分析了桨后整流支架的特点及其一般设计原则,以及基于动量理论、叶素理论和理想螺旋桨理论阐述了桨后整流支架的设计方法,最后给出了一个基于该设计方法的设计实例,并将本设计方法的计算结果与试验结果进行了分析比较,进一步验证了该方法的可行性。