220kV变电站扩建改造探讨

根据现阶段电网发展需要对220kV湖滨变电站进行扩建改造,通过论述原站改造及异地改建等改造方案,对该变电站扩建改造进行研究分析,为类似老站改造提供借鉴。

从巴林右旗的作法探讨草原建设的途径

为了探讨草原建设的途径,我们于1981年6月到内蒙古巴林右旗对草原建设进行了调查。我们认为,在草原建设方面他们是走在前面的,他们的做法和经验,值得提倡和推广,特别是北方牧区,更值得效法。 (一) 巴林右旗之所以在草原建设方面下了功夫,是有其深刻的教训的。该旗地处大兴安岭的东南缘,是我国著名的科尔沁草原的一部分。在全旗1445万亩的总面积中,草原占87.34％,达1286.8万亩,其中可利用草原1126.5万亩。全旗13个公社中牧业社占10个,牧民占总人口的90％,各族人民历来以牧业为主,有丰富的牧养经验。

西北地区退耕应优先还草

一、西北气候干旱,还草比还林的成活率高。 西部气候的突出特点是干旱少雨,退耕还林还草首先必须考虑的是哪个更容易成活。根据专家试验,降水一般在400毫米以上,造林才有较高的成活率,降水低于400毫米,一般需要配套一定的水利设施。而种草对降水的要求要宽一些,据甘肃省草原站试验,在甘肃中部干旱区年降水量280毫米的地方,紫花苜蓿也能成活。

数学练习题

三年级 一、用0、1、2、3、4、5、6、7、8、9这十个数字组成最大的十位数是( ),读作( );组成最小的个位数是( ),读作( )。 二、用简便方法计算①2001-54-946 ②48+72+52+28③873+369+1127 ④2348-348-76 三、一个用铁丝折成的长方形。

Microscopic phase-field modeling of atomic anti-site behaviors in precipitation progress of Ni_3(AlFe)

The effects of temperature on atomic anti-site behaviors in L12-Ni3(AlFe) phases were studied using microscopic phase-field dynamic model in precipitation progress of Ni75Al20Fe5 alloy.The results show that with the increase of temperature,the formation of NiAl and AlNi anti-sites is much easier in Ni3(AlFe),and Ni and Al anti-site atoms show clearly stronger temperature-dependent than Fe anti-site atoms.The evolution progress of anti-site atoms is completed at the initial growth stage of L12-Ni3(AlFe) phases.The site occupation probabilities of Ni atoms on the sublattice A(NiNi,face centers sites of FCC),and Al and Fe atoms on the sublattice B(AlAl and FeAl,corners sites of FCC) all present the degressive tendency with the temperature increasing.Fe atoms mainly prefer to occupy the Al sublattice at the whole temperature range.

Properties of summer radiation and aerosols at Xinzhou,a suburban site on the North China Plain

The properties of summer radiation and aerosols were studied at Xinzhou,a suburban site on the North China Plain(NCP)by using ground-based measurements in 2014.The radiation detections under clear and cloudy skies showed that longwave radiation presented a sigmate pattern,with a maximum of 392.6 W m-2at 1700 local standard time(LST)associated with the cloud radiative forcing,and a minimum of 360.0 W m-2at 0600 LST when the lowest surface temperature(17.1°C)occurred.Solar radiation,including global,direct,diffuse,photosynthetically active,ultraviolet-A,and ultraviolet-B,exhibited a single peak at^1300 LST.A bimodal size distribution,with fine mode aerosols showing a peak between 0.1 and 0.2μm and coarse mode aerosols showing a peak at^5μm,was observed at Xinzhou.The dominant aerosol type was black carbon coating on coarse particles(85.7%)for the cases with aerosol optical depth at 400 nm(AOD)greater than 0.4,leading to a lower single scattering albedo(0.81)than the typical value(~0.90)at the other stations on the NCP.The mean values of EAE and AAE(extinction and absorption?ngstr?m exponent,respectively)were 1.14±0.15 and 0.58±0.28 for the aerosol measurements.The average of instantaneous aerosol direct radiative forcing at the bottom of the atmosphere was-138.9±33.0 W m-2for the cases with AOD>0.4.The results in this study are expected to improve understanding at suburban sites on the NCP of aerosol properties and their impacts on regional radiation budgets.

Reasons Why the Great Pyramids of Giza Remain the Only Surviving Wonder of the Ancient World： Drawing Ideas from the Structure of the Giza Pyramids to Nuclear Power Plants

Selecting a site for a nuclear power plant requires extensive studies to ensure its safety and stability during its operation until its decommissioning. The 4,500-year old Egyptian pyramids at Giza are buildings to learn from. This paper tries to pin down the reasons for the survival of the Giza pyramids in order to reach a criterion for choosing sites for important buildings. It argues that the site selection and the geological properties of the area, being away from seismic effects,, floods and groundwater levels, the stability of the geometric form of the pyramid, the solidity of the structural engineering and precision of execution arguably are the reasons why the Great Pyramids of Giza are the only survivors of the seven wonders of the ancient world.

Development of a Low-Cost Weather Station to Measure in Situ Essential Climate Variables

A weather station is proposed especially designed for developing countries, and to meet the standards of the international scientific community making research on the earth system. The station would measure in situ several ECV （essential climate variables）. These data may enable an agricultural breakthrough in countries lacking meteorological infrastructure, help in climate change monitoring, and facilitate diffusion of wind energy. A pre-feasibility analysis is presented. It appears interesting that the station is supplied by a social enterprise. A research to establish the best shelter design using computational fluid dynamics is also reported. The criterion is the accuracy with which the surface air temperature is reproduced inside the shelter. A design following recommendations by the WMO （World Meteorological Organization）, a smaller design with identical geometry, and two alternative small designs are analyzed. All four designs are simulated in PVC, natural rubber and wood, with and without white paint coating. The smaller shelters perform better. The influence of the material, dimensions and design is smaller than that of the white paint. Shelters made of PVC or rubber, and/or in alternative designs, may be more interesting if other criteria are considered, like whether logistics, manufacturing, etc. are more sustainable, easier and/or cheaper.

Variations in Soil Temperature at BJ Site on the Central Tibetan Plateau

The temporal and spatial variation in soil temperature play a significant role in energy and water cycle between land surface and atmosphere on the Tibetan Plateau.Based on the observed soil temperature data（hourly data from 1 January 2001 to 31 December 2005）obtained by GAME-Tibet,the diurnal,seasonal and interannual variations in soil temperature at BJ site（31.37°N,91.90°E; 4509 m a.s.l.）near Naqu in the central Tibetan Plateau were analyzed.Results showed that the average diurnal variation in soil temperature at 4 and 20 cm depth can be described as sinusoidal curve,which is consistent with the variation of solar radiation. However,the average diurnal variation in soil temperature under 60 cm was very weak.The average diurnal amplitude in soil temperature decreased by the exponential decay function with the increase of soil depth（R2=0.92,p〈0.01）.It is demonstrated that the average diurnal maximum soil temperature decreased by the exponential decay function with the increase of soil depth（R2=0.78,p〈0.01）.In contrast, the average diurnal minimum soil temperature increased by the exponential grow function with increasing of soil depth（R2=0.86,p〈0.01）.There were a linear negative correlation between the average annual maximum Ts and soil depth（R2=0.96, p〈0.01）,a logarithmic function relationship between the average annual minimum soil temperature and soil depth（R2=0.92,p〈0.01）.The average seasonal amplitude in soil temperature followed the exponential decay function with the increase of soil depth（R2=0.98,p〈0.01）.The mean annual soil temperature in each layer indicated a warming trend prominently.During the study period,the mean annual soil temperature at 4,20,40,60,80,100,130, 160,200 and 250 cm depth increased by 0.034,0.041, 0.061,0.056,0.062,0.050,0.057,0.051,0.047 and 0.042℃/a,respectively.

Influence of site conditions on ground motion at far field loess sites during strong earthquake

Loess is widely distributed in China and the Loess Plateau is one of the major areas where strong earthquakes often take place. The seismic amplification effects were discovered in the Plateau during the Wenchuan Ms8.0 earthquake and some other strong events. Based on earth tremor observation, borehole exploration and site seismic response analysis, the site effects of topography of Loess Yuan on ground motion were investigated in details. The earth tremor investigation shows that predominant frequencies at the bottom sites of Loess Yuan are greater than those at the top obviously. The sites seismic response analysis shows that the Loess Yuan may amplify peak ground acceleration (PGA) by 1.44 2.0 times. Therefore, site effects of mountains and loess topography on ground motion should be taken account into in seismic design in loess regions.

Declining Precipitation Enhances the Effect of Warming on Phenological Variation in a Semiarid Tibetan Meadow Steppe

Vegetation phenology is a sensitive indicator of global warming,especially on the Tibetan Plateau.However,whether climate warming has enhanced the advance of grassland phenology since 2000 remains debated and little is known about the warming effect on semiarid grassland phenology and interactions with early growing season precipitation.In this study,we extracted phenological changes from average NDVI in the growing season（GNDVI） to analyze the relationship between changes in NDVI,phenology and climate in the Northern Tibetan Damxung grassland from 2000 to 2014.The GNDVI of the grassland declined.Interannual variation of GNDVI was mainly affected by mean temperature from late May to July and precipitation from April to August.The length of the growing season was significantly shortened due to a delay in the beginning of the growing season and no advancement of the end of the growing season,largely caused by climate warming and enhanced by decreasing precipitation in spring.Water availability was the major determinant of grass growth in the study area.Warming increased demand for water when the growth limitation of temperature to grass was exceeded in the growing season.Decreased precipitation likely further exacerbated the effect of warming on vegetation phenology in recent decades due to increasing evapotranspiration and water limitations.The comprehensive effects of global warming and decreasing precipitation may delay the phenological responses of semiarid alpine grasslands.

A first-principles study of site occupancy and interfacial energetics of an H-doped TiAl-Ti_3 Al alloy

We investigate the site occupancy and the interfacial energetics of TiAl-Ti3Al binary-phase system with H using a first-principles method. H energetically prefers to occupy the Ti-rich octahedral interstitial site because H prefers to bond with Ti rather than with Al. The occupancy tendency of H in the binary phase TiAl-Ti3Al alloy from high to low is α2-Ti3Al to γ/α2 interface and 7-TiAl, because the decrease of the Ti local concentration is in the same order. We demonstrate that H can largely affect the mechanical properties of the TiAl-Ti3Al system. On the one hand, H at the interface reduces the interface energy with the H2 molecule as a reference, implying the TiAl/Ti3Al interface is stabilized. On the other hand, the ratio between the cleavage energy and the unstable stacking fault energy decreases after H-doping, indicating H will reduce the ductility of the TiAl/Ti3Al interface. Consequently, the mechanical property variation of TiA1 alloy due to the presence of H not only depends on the amount of TiAl/Ti3Al interfaces but also is related to the H concentration in the alloy.

First-principles study of carbon effects in a tungsten grain boundary:site preference, segregation and strengthening

First-principles calculations have been performed to investigate energetics and site preference of carbon (C) in a tungsten (W) 5(310)/[001] grain boundary (GB). We calculate the solution energies of the C atom in the GB, which show that the interstitial C is energetically favored over the substitutional C. The segregation energy is calculated to be 3.95 eV for the energetically favorable GB interstitial site, indicating that C energetically prefers to segregate into the W GB. Based on the Rice-Wang model, our total energy calculations show that C has a significant beneficial effect on the W GB cohesion.

Skeletal element distributions of the large herbivores from the Lingjing site,Henan Province,China

More than ten thousands of bone fragments were recovered from the Lingjing site, Henan Province during 2005 and 2006. In this paper, through the quantification and statistical analyses of the skeletal elements of the two predominant species in this assemblage, aurochs (Bos primigenius) and horse (Equus caballus), the differential influences and weights of a variety of taphonomic agencies in the formation of the assemblage are assessed respectively. Compared to the natural agencies, hominid hunting and the subsequent disarticulation, slaughtering, and their transport of the bone elements of the prey species are the main factors accounting for the formation of the present assemblage. More importantly, this study initiatively identifies hominid's differential treatment of the bones of aurochs and horse in the Paleolithic record of East Asia and demonstrably suggests that hominids at the site have already practiced sophisticated hunting techniques and subsistence strategies and may be quite familiar with the ecological and anatomical characteristics and nutritional values of the large-sized prey animals and can accordingly take different processing and handling strategies at the hunting site.

Variations in soil moisture over the ‘Huang-Huai-Hai Plain＇ in China due to temperature change using the CNOP-P method and outputs from CMIP5

In this study, the variations in surface soil liquid water(SSLW) due to future climate change are explored in the‘Huang-Huai-Hai Plain'(‘3H') region in China with the Common Land Model(CoLM). To evaluate the possible maximum response of SSLW to climate change, the combination of the conditional nonlinear optimal perturbation related to the parameter(CNOP-P) approach and projections from 10 general circulation models(GCMs) of the Coupled Model Intercomparison Project5(CMIP5) are used. The CNOP-P-type temperature change scenario, a new type of temperature change scenario, is determined by using the CNOP-P method and constrained by the temperature change projections from the 10 GCMs under a high-emission scenario(the Representative Concentration Pathway 8.5 scenario). Numerical results have shown that the response of SSLW to the CNOP-P-type temperature scenario is stronger than those to the 11 temperature scenarios derived from the 10 GCMs and from their ensemble average in the entire ‘3H' region. In the northern region, SSLW under the CNOP-P-type scenario increases to0.1773 m^3 m^(-3); however, SSLW in the scenarios from the GCMs fluctuates from 0.1671 to 0.1748 m^3 m^(-3). In the southern region,SSLW decreases, and its variation(–0.0070 m^3 m^(-3)) due to the CNOP-P-type scenario is higher than each of the variations(–0.0051 to –0.0026 m^3 m^(-3)) due to the scenarios from the GCMs.

Shifts in water-level variation of Namco in the central Tibetan Plateau from ICESat and Cryo Sat-2 altimetry and station observations

The dynamics of high-altitude inland lakes in the Tibetan Plateau are sensitive indicators of climate change. Due to the remoteness and hard access, satellite altimetry becomes an effective approach to obtaining largescale and temporally continuous information of lake-level changes. The CryoSat-2 altimetry is expected to solve the current problem that earlier radar altimeters are only practical for monitoring large water bodies, while ICESat laser altimetry is available only for the period 2003-2009. In this study, the comparison of CryoSat-2 altimetry for Namco with in situ water-level data suggests a high cor- relation coefficient of 0.71 （P 〈 0.01）, with the mean error of -0.12 m and root-mean-square error of 0.18 m. Further, the combination of ICESat and CryoSat-2 altimetry data and in situ lake-level observations reveals a rapid water- level rise of 0.24 4- 0.04 m/year during 2003-2008 and then a slightly decreasing trend of -0.09 4- 0.04 m/year during 2009-2013. This study suggests that the CryoSat-2 altimetry has the potential of sustaining the fine observa- tions on Tibetan lakes, following the ICESat mission. Besides, the examination of four key climatic variables （temperature, precipitation, potential evapotranspiration, and relative humidity） during 1990-2013 indicates that the wetting climate over Namco Basin stagnated or even reversed around 2006, which may be tightly related to the slowing lake growth.

Principle of in-situ 3D rock stress measurement with borehole wall stress relief method and its preliminary applications to determination of in-situ rock stress orientation and magnitude in Jinping hydropower station

As a main constituent of geological body, the rock masses have distinct differences from other materials, one of which is that rock masses are initially stressed in their natural states. Hence, it is an extremely challenging and significant research project to know the present residual stress of the rock masses in the earth's crust. Although some regularities of distribution of in-situ rock stresses can be deduced, the basic means to study the state of rock stress is in-situ stress measurement. After a brief review of several measuring methods of in-situ 3D rock stress, a new one, borehole wall stress relief method (BWSRM) to determine the in-situ 3D rock stress tensor in a single drilled borehole was proposed. Based on the principle of in-situ rock stress measurement with BWSRM, an original geostress measuring instrument was designed and manufactured. Preliminary experiments for determination of in-situ stress orientation and magnitude were carried out at an experimental tunnel in Jinping Ⅱ hydropower station in China, where the buried depth of overburden was about 2430 m. The results showed that it was feasible to measure the in-situ 3D rock stresses with BWSRM presented in this paper. The BWSRM has a broad prospect for in-situ 3D rock stress measurements in practical rock engineering.

In-situ measurement of atmospheric CFC-11 at the Shangdianzi Global Atmosphere Watch(GAW) Regional Station

An in-situ GC-ECD system was used to measure halocarbons at Shangdianzi （SDZ） GAW regional station. In this paper, we reported observational results of atmospheric CFC- 11 （CCI3F） mixing ratios from April 2007 to March 2008. The CFC- 11 time series showed large variability. Approximately 62% observed values were filtered as non-background data. The median, 10% and 90% percentiles of CFC-11 background mixing ratios were 245.4 ppt （10-12 mol/mol）, 244.6 ppt and 246.1 ppt, respectively; whereas those of non-background CFC- 11 mixing ratios were 254.7, 246.6 and 272.1 ppt, respectively. Significant differences in background and non-background CFC-11 mixing ratios were observed between summer and autumn, mainly because of the CFC-11 stored in loam being prone to atmospheric release in hot seasons. Comparison of tile SDZ data with the five AGAGE stations suggested agreement with mid-high latitude Northern Hemisphere stations MHD, THD and RPB. The SDZ data were higher than that of Southern Hemisphere stations CGO and SMO. Higher CFC-11 mixing ratios measured in different seasons were always associated with winds from the W-WSW-SW sector, indicating that the airflow coming from this wind sector has a positive contribution to CFC- 11 concentrations. The CFC-11 mixing ratios were higher in autumn and summer than in spring and winter, in which its mixing ratios were very close to the atmospheric background level. This was happened especially when airflow originated from the NNE-NE-ENE-E sector, indicating the air masses coming from these wind directions was relatively clean.