站用10 kV系统中性点接地方式对避雷器地电位升安全限值的影响

随着电网容量变大和新型电力系统的发展,站用10 kV系统中性点接地方式发生改变,仍沿用系统中性点不接地方式下避雷器耐受接地网地电位(U_(GPR))升高的安全限值可能会导致避雷器在其他接地方式下出现安全事故。采用电磁暂态程序ATP-draw可以搭建不同中性点接地方式下U_(GPR)反击避雷器的模型,通过校核避雷器在U_(GPR)作用下动作过程中的吸收能量,得到了中性点接地方式对避雷器耐受U_(GPR)安全限值的影响规律:中性点不接地时,避雷器耐受U_(GPR)安全限值为10~23 kV,随线路对地电容变大而减小;中性点经消弧线圈接地时,U_(GPR)在消弧线圈和线路对地电容的串联回路中产生振荡,导致避雷器耐受U_(GPR)安全限值更低,安全限值主要由脱谐度与阻尼率决定,典型值为8~9.5 kV;中性点经电阻接地时,U_(GPR)大部分耦合至高压母线,使避雷器耐受U_(GPR)安全限值更高,并随线路对地电容和中性点电阻的增大而减小,大电阻接地工况下的典型值大于15 kV,小电阻接地工况下的典型值大于25 kV。

高地温TBM铁路隧道施工应对措施研究

为了改善高地温TBM铁路隧道的高温热害问题,依托某特长铁路隧道工程,通过大量资料调研并综合国内外已有高地温TBM隧道施工降温技术措施,同时结合该隧道高地温具体情况,提出了一套系统的TBM高地温隧道热害防治的综合降温技术方案。研究表明,综合国内外地下洞室施工温度控制标准,建议高地温TBM铁路隧道洞内施工温度控制在28℃以下;采用加强通风、洒水降温、冰块降温、人工制冷等降温技术并结合隧道支护体系防热措施可防治TBM隧道高岩热;采用红外探水超前预测、化学注浆、热水归管引排等“以防堵为主,引水排水相结合”的原则可防治TBM隧道高温热水。根据该隧道热害具体情况采用热害分级防控总原则,将隧道热害分为4个等级并采取针对性治理措施,减少热害防控对施工进度的影响,节约经济。研究成果可为高地温TBM铁路隧道及其他类似工程提供参考。

《内经》使道学说临床研究

“使道”一词首见于《黄帝内经》。《素问·灵兰秘典论》曰:“主不明则十二官危,使道闭塞而不通,形乃大伤,以此养生则殃。”精辟地道明了人体健康生命过程维持的关键,除了“主明”,还需要“使道通”。1使道学说的历史背景使道学说的起源。

《温热论》凉血散血法在眼底血证治疗中的运用体会

眼底血证属中医“血证”范畴,是眼底出血性疾病的统称,本病具有“外不见症,从内而蔽之”的特点,其病因复杂、病程缠绵、严重影响患者视力[1]。现代眼科学中的眼底血证包括老年性黄斑变性、视网膜静脉阻塞、视网膜静脉周围炎、眼外伤等多种原因导致的视网膜及脉络膜出血[2]。

沿空留巷巷道加固技术研究

为了减少沿空留巷巷道底鼓和帮鼓,提高留巷巷道二次复用成功率,特提出了锚索+工字钢梁+钢筋网片+混凝土加固底板技术以及煤帮锚索补强措施。文章以余吾煤业N1100综放工作面柔模混凝土沿空留巷巷道为背景,在此巷道进行工业性实践,通过留巷巷道围岩收敛变形量观测,未采用加固段巷道底鼓量稳定在1200 mm左右,巷道帮鼓量稳定在850 mm左右,采用底板加固技术和煤帮补强措施后巷道底鼓量稳定在280 mm左右,巷道帮鼓量稳定在120 mm左右。结果表明:采用加固底板技术和煤帮锚索补强措施可减少底鼓77%,减少帮鼓86%.实践可知,采用底板加固技术和煤帮补强措施能够有效控制沿空留巷巷道的底鼓和帮鼓。

铁路隧道柔性棚洞优化方案研究

我国西南山区地形复杂、山高坡陡,危岩落石是极为普遍的地质灾害问题。由于其分布范围广,线路选线时难以完全避绕,给铁路运营带来重要的安大隐患,目前隧道洞口设置明(棚)洞是一种常见的危岩落石防护措施。文章在比较分析不同棚洞类型的优缺点后,提出新一代柔性棚洞设计理念,该类型棚洞参考现有的柔性钢棚洞系统,创新性地引入索托柱结构,使主体钢架结构与柔性防护结构分离开来,有效明确了两者的相互关系与作用。索托柱结构位于主体钢架结构与柔性防护结构之间,一端连接于主体钢架结构,另一端连接与柔性结构。该类型棚洞拦挡危岩落石过程中,落石可能最终堆积于防护网内,也可能多次回弹运动后远离防护网,实现危岩落石自清理。该索托式柔性缓冲结构能够明显降低落石直接击中主体钢架结构的概率,保证棚洞结构的整体安全性,同时能够有效控制棚洞结构变形,具有大范围推广的工程应用意义。

高海拔隧道施工人员劳动时间调整研究

为探究高海拔隧道施工人员体力劳动强度水平,提供劳动时间调整依据,选择圭嘎拉隧道进口段(海拔4300 m)的施工人员作为测试对象,测量不同工序下施工人员的肺通气量和耗氧量。基于耗氧量计算平均能量代谢率,进而计算各工序劳动强度指数,调整劳动时间。结果表明:(1)二次衬砌钢筋绑扎是所测施工工序中劳动强度最大工序,该工序下施工人员工作日总能量代谢率超过卫生限值,劳动强度指数达到35(极重);(2)海拔4300 m隧道施工工序劳动强度大部分为中度—极重;(3)规范中基于肺通气量的平均能量代谢率计算公式并不完全适用于高海拔地区。

基于ADAMS的带有防失速短节钻头动力学仿真研究

针对石油天然气钻井作业中所遇到的由于坚硬多变岩层造成的钻头抗冲击能力差、易损坏等问题,提出一种连续油管钻井自适应进给系统,设计一种带有安全保护功能的防失速短节。采用交变力、线性变化的力和恒力模拟钻进不同硬度的地层,利用ADAMS软件仿真钻进过程,探求钻头进给速度随不同地层硬度的变化规律,结果表明该钻井系统对硬度变化的岩层具有自适应性。用不同速度的质量块分别撞击带有防失速短节和无防失速短节钻头,模拟钻头突然撞击坚硬岩层,得到钻头瞬间所受的冲击力,结果表明:带有防失速短节的钻井系统具有良好的缓冲性能,可以有效地保护钻头。

TBM开挖深埋铁路隧道引起的围岩扰动分析

TBM深埋铁路隧道地应力水平高,应力场复杂多变。为研究TBM开挖深埋铁路隧道引起的围岩扰动,明确其应力重分布特征及产生机制,依托实际铁路隧道工程,采用FLAC 3D数值模拟软件,建立TBM隧道施工掘进模型,基于力流理论对TBM隧道开挖过程中的围岩应力分布特征及弹性应变能进行分析,采用弹性应变能大小为指标对隧道岩爆位置进行预测。研究结果表明:1)隧道围岩应力及弹性应变能大致呈上下对称分布,TBM的质量对围岩应力分布影响不大;2)在水平构造型应力场中,σx(横向应力)的重分布对σ1(最大主应力)的应力集中程度影响显著,拱顶和拱底、拱肩和拱脚、拱腰处最大主应力集中分别主要由横向应力、剪应力、竖向应力集中引起;3)σ1的应力集中程度反映了弹性应变能的跃升水平,隧道拱底和拱顶发生岩爆的可能性最大。

智能电能表全性能试验管理信息系统设计与实现

智能电能表作为坚强型智能电网的重要组成部分,在整个电网建设中起着十分重要的作用。针对智能电能表全性能试验的自动化和信息化程度不高的问题,基于C/S和B/S混合构架对智能电能表全性能试验管理信息系统进行设计,并搭建数据库对所设计的系统进行了软件实现。测试结果表明,该信息系统安全稳定,满足了实际应用的需求。

Observed features of temperature, salinity and current in central Chukchi Sea during the summer of 2012

During the summer of 2012, the fifth CHINARE Arctic Expedition was carried out, and a submersible mooring system was deployed in M5 station located at （69°30.155＇N,169°00.654＇W） and recovered 50d later. A set of temperature, salinity and current profile records was acquired. The characteristics of these observations are analyzed in this paper. Some main results are achieved as below. （1） Temperature generally decreases while salinity generally increases with increasing depth. The average values of all records are 2.98℃ and 32.21 psu. （2） Salinity and temperature are well negatively correlated, and the correlation coefficient between them is -0.84. However, they did not always vary synchronously. Their co-variation featured different characters during different significant periods. （3） The average velocity for the whole water column is 141 mm/s with directional angle of 347.1°. The statistical distribution curve of velocity record number gets narrower with increasing depth. More than 85% of the recorded velocities are northward, and the mean magnitudes of dominated northward velocities are 100-150 mm/s. （4） Rotary spectrum analysis shows that motions with low frequency take a majority of energy in all layers. The most significant energy peaks for all layers are around 0.012 cph （about 3.5 d period）, while the tidal motion in mooring area is nonsignificant. （5） Velocities in all layers feature similar and synchronous temporal variations, except for the slight decrease in magnitude and leftward twist from top to bottom. The directions of velocity correspond well to those of Surface wind. The average northward volume transport per square meter is 0.1-0.2 m3/s under southerly wind, but about -0.2 m3/s during northerly wind burst.

The Distribution and Variability of Simulated Chlorophyll Concentration over the Tropical Indian Ocean from Five CMIP5 Models

Performances of 5 models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) in simulating the chloro-phyll concentration over the tropical Indian Ocean are evaluated. Results show that these models are able to capture the dominant spatial distribution of observed chlorophyll concentration and reproduce the maximum chlorophyll concentration over the western part of the Arabian Sea, around the tip of the Indian subcontinent, and in the southeast tropical Indian Ocean. The seasonal evolution of chlorophyll concentration over these regions is also reproduced with significant amplitude diversity among models. All of 5 mod-els is able to simulate the interannual variability of chlorophyll concentration. The maximum interannual variation occurs at the same regions where the maximum climatological chlorophyll concentration is located. Further analysis also reveals that the Indian Ocean Dipole events have great impact on chlorophyll concentration in the tropical Indian Ocean. In the general successful simulation of chlorophyll concentration, most of the CMIP5 models present higher than normal chlorophyll concentration in the eastern equatorial Indian Ocean.

Ocean current observation and spectrum analysis in central Chukchi Sea during the summer of 2008

During the summer of 2008, the third CHINARE Arctic Expedition was carried out on board of Xuelong Icebreaker in the central Chukchi Sea. A submersible mooring system was deployed and recovered at Station CN-01 （71.40.024＇N, 167.58.910＇W） with 33 days of the current profile records, and continuous observation of temperature and salinity data were collected. This mooring station locates in the blank of similar observation area and it is the first time for our Chinese to finish this kind of long-term mooring work in this area. This mooring system finished integrated hydrological observations with long-term continuous record of the whole profile velocity for the first time. Based on time series analysis of temperature, salinity, velocity and flow direction, we get the following main results. （1） During the observation period, the mean surface current velocity is 70.2 cm/s eastward, and velocity reaches its maximum in average at 3 m level with magnitude 90.0 cm/s, direction 206.. （2） In 9-30 m layers, the semidiurnal period variation is the most obvious, the flow direction is quite stable, and the flow is synchronous and consistent vertically. （3） Besides the semidiurnal period variation, the main variation in the upper layer is in 11-d period, with variations in period 5.5, 5.5, and 3.7 d, which reflect the influences of sea surface wind change and maintenance. （4） Near the bottom the temperature change is correlated and synchronized with the conductivity.

Dramatic weakening of the ear-shaped thermal front in the Yellow Sea during 1950s–1990s

The ear-shaped thermal front （ESTF）, formed by the convergence of the Yellow Sea Warm Current （YSWC） and the Shandong Coastal Current （SCC）, is a very important oceanic phenomenon in the Yellow Sea （YS） in winter. In situ measurements and reanalysis datasets all demonstrate that the ESTF has been weakening during 1950s-1990s, and a similar weakening trend is also found in winter monsoon over the YS. Numerical experiments show that the weakening of winter monsoon can induce an anomalous circulation in the YS on multi-decadal timescale with northward anomalous currents along China＇s coast and southward anomalous currents in the central YS--generally opposite to seasonal mean circulation. The anomalous circulation causes slowdown of the YSWC and the SCC, and thus weakens the ESTF. Since the ESTF plays important roles in regional ocean dynamics and air-sea interactions, its weakening has important implications for regional climate in the YS in winter.

The observed tidal and residual currents in the Andaman Sea during the second half of 2016

The characteristics of currents and tidal currents in the Andaman Sea（AS） are studied during the second half of2016 using observed data from a moored acoustic Doppler current profiler（ADCP） deployed at 8.6°N, 95.6°E.During the observation period, the mean flow is 5–10 cm/s and largely southward. The root mean square and kinetic energies of the low and high frequency flows, which are divided by a cutoff period of 5 d, are at the same level, indicating their identical importance to the total current. A power spectrum analysis shows that intraseasonal oscillations, a tidal-related semilunar month signal, a semidiurnal tidal signal and periods of 3–4 d are prominent. The barocliny of an eddy kinetic energy is stronger than the mean kinetic energy, both of which are the strongest on the bottom and the weakest at 70 m depth. Residual currents are largely southward（northward） during the summer（winter） monsoon season. Two striking peaks of the southward flow cause the 80 d period of meridional currents. The first peak is part of a large-scale circulation, which enters the AS through the northern channel and exits through the southern channel, and the second peak is part of a local vortex. The 40 d oscillation of the zonal current is forced by geostrophic variations attributed to local and equatorial remote forcing. The tidal current is dominated by semidiurnal constituents, and among these, M2 and N2 are the top two largest major axes. Moreover, astronomical tidal constituents MM and MSF are also significant. Diurnal constituents are weak and shallow water tides are ignorable. The aims are to introduce the new current data observed in the AS and to provide initial insights for the tidal and residual currents in the Andaman Sea.

Tide and Current Observations in the Central Chukchi Sea During the Summer of 2012

Current data from a moored Acoustic Doppler Current Profiler(ADCP) deployed at 69?30.155′N,169?00.654′W in the central Chukchi Sea during 2012 summertime is analyzed in the present paper.Characteristics of tidal and residual currents are ob-tained with Cosine-Lanczos filter and cross-spectral analyses.The main achievements are as follows:1) Along with the local inertial frequency of 12.8 h,two other peaks at ~12-h and ~10-d dominate the time series of raw velocity;2) The M_2 dominates the 6 resolved tide constituents with significant amplitude variations over depth and the ratios of current speed of this constituent to that of the total tidal current are 54% and 47% for u and v components,respectively.All the resolved tidal constituents rotate clockwise at depth with the exception of MM and O1.The constituents of M_2 and S_2 with the largest major semi-axes are similar in eccentricity and orientation at deeper levels;3) The maximum of residual currents varies in a range of 20–30 cms^(-1) over depth and the current with lower velocities flow more true north with smaller magnitudes compared to the current in surface layer.The ~10 d fluctuation of residual current is found throughout the water column and attributed to the response of current to the local wind forcing,with an approximate 1.4 d lag-time at the surface level and occurring several hours later in the lower layer;4) Mean residual currents flow toward the north with the magnitudes smaller than 7 cms^(-1) in a general agreement with previous studies,which suggests a relatively weaker but stable northward flow indeed exists in the central Chukchi Sea.

Extreme Sea Level Rise off the Northwest Coast of the South China Sea in 2012

Tide gauge data are used to investigate sea level variability off the northwest coast of the South China Sea(SCS) in 2012,and a significant sea level elevation with a magnitude approaching 79 mm is observed.Analysis suggests that an abnormal sea surface heat flux and freshwater flux may have contributed to this abnormal rise in sea level,together with the remote influence of an ENSO event.Further investigation shows that the event was dominated by the positive freshwater flux,where large volumes of water entered the ocean,and a maximum is centered to the south of Guangdong province,China.Simultaneously,a positive anomalous heat flux occurred in the northwestern part of the SCS,which is considered to have made a positive contribution to the high local sea level elevation.In addition to the heat flux,the ENSO event also had a significant effect on the event,where the La Ni?a-induced northwest Pacific cyclone contributed to sea level rise over the northwestern SCS through dynamic and thermodynamic interactions.

Zooplankton diel vertical migration and influence of upwelling on the biomass in the Chukchi Sea during summer

The diel vertical migration （DVM） of zooplankton and the influence of upwelling on zooplankton biomass were examined using water column data of current velocity and mean volume backscattering strength （MVBS） collected by moored acoustic Doppler current profilers （ADCPs） deployed in the southeastern Chukchi Sea during the 5th Chinese National Arctic Research Expedition （CHINARE） in summer 2012, combined with the satellite observational data such as sea surface temperature （SST）, wind, and chlorophyll a （Chl a）. Hourly acoustic data were continuously collected for 49-d in the mooring site. Spectral analysis indicated that there were different migrating patterns of zooplankton, even though precisely classifying the zooplankton taxa was not available. The prevailing 24-h cycle corresponded to the normal DVM with zooplankton swimming upwards at sunrise and returning to deep waters at sunset. There was a clear DVM in the upper 17 m of the water column during the period with distinct day-night cycles, and no active DVM throughout the water column when the sun above the horizon （polar day）, suggesting that light intensity was the trigger for DVM. Also there was a second migrating pattern with 12-h cycle. The upwelling event occurring in the northwest of Alaskan coastal area had important influence on zooplankton biomass at the mooring site. During the upwelling, the SST close to the mooring site dropped significantly from maximal 6.35℃to minimal 1.31℃ within five days. Simultaneously, there was a rapid increase in the MVBS and Chl a level, suggesting the aggregation of zooplankton related to upwelling.

高原铁路钻爆法隧道断面优化研究

对高原铁路钻爆法隧道断面影响因素进行分析,并重点从气动效应、接触网悬挂及轨下结构布置三个影响因素开展断面优化研究。研究结果表明,从气动效应方面高海拔地区隧道断面具有优化的空间,接触网悬挂类型及悬挂高度对隧道断面的高度影响大,沟槽布置主要影响隧道断面宽度方向。结合不同的海拔跨度,提出了以海拔为分级依据的隧道断面优化方案。

高海拔隧道施工劳动强度与供氧浓度关系研究

为研究高海拔隧道施工人员供氧浓度问题,文章通过骑行试验得到了不同人员在海拔高度为590~4000 m,氧气浓度为20.9%~29%,骑行功率为0、50 W、75 W、100 W工况下的生理指标,得到测试对象的劳动强度指数,分析研究得到以下结论:(1)在同一海拔高度、相同劳动强度工况下,提升环境氧气浓度,可以显著降低人员劳动强度指数;(2)劳动强度指数的减少与氧气浓度的增加并不是线性关系,当环境氧气浓度超过25%时,劳动强度指数的降低程度有限;(3)拟合得到了劳动负荷为100 W且氧气浓度为20.9%~25%时施工人员的劳动强度指数与海拔高度及供氧浓度的关系式。