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1.
为满足地应力精确测量和长期监测的技术发展要求,基于空心包体应变计地应力测量技术,通过对采集电路稳定性、完全温度补偿技术数字化及复杂环境下装备适应性进行研究,开发出具有瞬时采集、断电续采功能的前端数字化采集系统。基于温度自补偿技术及双温度补偿设计实现完全温度补偿技术在前端数字化型空心包体应变计地应力测量中的应用。室内标定试验和现场测试数据显示,双温度补偿技术对原温度补偿算法数据的修正量达到15%。采用围压率定法和真三维地应力试验台进行模拟现场条件的室内测试,结果显示数据真实反映空间应力变化。在3组现场地应力测量中,应变数据真实反映解除过程的岩芯缺陷、构造扰动、温度变化影响及解除应力演化过程,双温度影响修正应变值分别为64,86με。在温度强扰动条件下,通过双温度补偿算法修正,数据稳定性仍然达到了30 min内数据波动幅度小于5με的标准。双温度补偿算法的瞬接续采型前端数字化空心包体应变计地应力测量技术在室内试验和现场测试中均表现了良好的测试精度和采集系统稳定性。  相似文献   
2.
探讨了澳大利亚CSIRO型空心包体式钻孔三向应变计的测量技术,重点介绍了测量元件应变片的布置形式和利用围压加载试验成果修正原始解除应变实测值的方法。对解除应变实测值的修正提出了具体方法,由修正后的解除应变推算的地应力实测值更精确。在三峡工程永久船闸开挖完成后岩体应力动态变化测量中,具体分析了测量元件应变片黏贴部位和角度的误差所引起的地应力实测值的误差,具体实施了对解除应变实测值的修正,实测的岩体应力动态变化更符合工程实际情况。  相似文献   
3.
This paper is the second dealing with measurement-related uncertainties of overcoring data undertaken at the Äspö Hard Rock Laboratory and focuses on the biaxial test data from CSIRO HI overcore samples. The first paper dealt with measurement-related uncertainties in connection with the overcoring phase [1].The uncertainties identified in connection to biaxial tests of CSIRO HI overcore samples include too large applied pressures and poor sampling frequency. At the Äspö HRL, the results yield that most overcore samples fractured during biaxial testing, meaning that a significant part, 56%, of available strain gauge combinations were removed from calculations of the elastic parameters. Remaining strain gauge combinations indicate average values of 62±5 GPa for Young's modulus and 0.25±0.01 for Poisson's ratio, which are considerably lower than previously published values [2–5], and are in good agreement with results from biaxial tests on Borre Probe overcore samples [6–10]. The stress calculations were obtained from re-analyzed elastic parameters and strains, and show primarily a reduction in stress magnitudes. Overall, the stress field obtained with different stress measurement methods and its variation with depth is now quite well resolved. The overcoring data suggest that the principal stresses are inclined with a vertical component dipping about 65° from the horizontal over the investigated rock volume (140–420 m depth). This is interpreted as a result of influence from the sub-vertical NE-2 Fracture Zone that divides the stress data into two stress domains [11], although it may also be an artefact because the σ2- and σ3-magnitudes are of the same order of magnitude.  相似文献   
4.
A new method of estimating per-pixel atmospheric column water vapor (ACWV) and potential differences in the reported band center wavelengths of the HyMap sensor has been developed. The new method uses variations of a second order derivative algorithm (SODA) to assess the impact of atmospheric residual features on calculated surface reflectance spectra after atmospheric compensation. The SODA method provides an alternative to the current band ratio techniques of ACWV estimation and also allows the same form of algorithm to be used for the estimation of possible band shifts. A comparison of in-situ measured surface reflectance at two field sites in Western Australia demonstrates improvement in the resulting spectra when post-flight updates are made to the reported HyMap band center wavelengths and applied during the atmospheric compensation process. The same SODA methodology was varied to estimate the ACWV on a per-pixel basis and found to significantly reduce the appearance of the underlying surface structure on the resulting ACWV images as well as improve the overall accuracy of the estimation. The ACWV estimated from the HyMap imagery at the two field sites was found to agree with in-situ atmospheric ACWV measurements to within 2% and represented a two fold increase in accuracy over a 3 band ratio Continuum Interpolated Band Ratio (CIBR) technique of ACWV estimation.  相似文献   
5.
As part of the European Mercury Emissions from Chlor Alkali Plants (EMECAP) project, we tested the hypothesis that contamination of ambient air with mercury around chlor alkali plants using mercury cells would increase the internal dose of mercury in people living close to the plants. Mercury in urine (U-Hg) was determined in 225 individuals living near a Swedish or an Italian chlor alkali plant, and in 256 age- and sex-matched individuals from two reference areas. Other factors possibly affecting mercury exposure were examined. Emissions and concentrations of total gaseous mercury (TGM) around the plants were measured and modeled. No increase in U-Hg could be demonstrated in the populations living close to the plants. This was the case also when the comparison was restricted to subjects with no dental amalgam and low fish consumption. The emissions of mercury to air doubled the background level, but contributed only about 2 ng/m(3) to long-term averages in the residential areas. The median U-Hg levels in subjects with dental amalgam were 1.2 microg/g creatinine (micro/gC) in Italy and 0.6 microg/gC in Sweden. In individuals without dental amalgam, the medians were 0.9 microg/gC and 0.2 microg/gC, respectively. The number of amalgam fillings, as well as chewing, fish consumption, and female sex were associated with higher U-Hg. The difference between the countries is probably due to higher fish consumption in Italy, demethylated methyl mercury (MeHg) being partly excreted in urine. Post hoc power calculations showed that if the background mercury exposure is low it may be possible to demonstrate an increase in U-Hg of as little as about 10 ng/m(3) as a contribution to ambient mercury from a point source.  相似文献   
6.
We conducted a study within the framework of the interdisciplinary European Mercury Emission from Chloralkali Plants (EMECAP) project to assess exposure to mercury (Hg) and the contribution of Hg emissions from a mercury cell chloralkali plant to urinary mercury (U-Hg) in adults living near the plant. We collected data from questionnaires and first morning urine samples from 75 subjects living near the Tarnow plant in Poland and 100 subjects living in a reference area. Median U-Hg was 0.32 mug/g creatinine (microg/gC) and 0.20 microg/gC, respectively. The median U-Hg was also higher in the amalgam-free subjects living near the plant (0.26 microg/gC) than in the reference group (0.18 microg/gC), but no such association was found in a multivariate analysis. There was a statistically significant positive association between U-Hg and number of teeth with amalgams, a negative association with age and a tendency towards higher U-Hg in female subjects. In the amalgam-free subjects there were statistically significant effects of female sex and fish consumption, and a negative association with age. The additional long-term average air Hg concentration from the plant, based on EMECAP environmental measurements and modelling, was estimated to be 1-3.5 ng/m(3) for the residential study area and should have a very small effect on U-Hg. The other Hg emission sources such as coal combustion facilities located nearby should be taken into account in assessing the overall impact of air Hg on U-Hg in this area.  相似文献   
7.
在地下工程的中尤其深部工程,地应力是指导开挖的重要参数之一,因此,地应力测量工作至关重要.CSIRO地应力测量法是国际岩石力学学会推荐的地应力测量方法之一.针对三山岛金矿深部巷道近千米花岗岩钻机取芯,精密加工成标准圆柱试件,进行单、三轴压缩试验,获取霍克布朗-准则强度准则曲线,重点设计单岩样多围压阶梯弹性段加载试验.通过试验数据计算获得岩石弹性模量和泊松比等物理力学参数,引入体积模量K和剪切模量G等变形参量,且随平均应力不断增大成非线性变化的关系,应用双曲线函数模型建立变形参量与平均应力的本构关系■.公式中K_0/G_0为初始变形模量,K_0/G_0+1/a为平均应力无限大时趋近值,1/b为变形模量初始增长率,三参数都具有明确的物理意义.基于此公式推导考虑岩石非线弹性变形特征的CSIRO地应力测量法中高压双轴公式,通过三山岛金矿深部花岗岩解除岩芯高压双轴加载试验验证此公式的适用性.  相似文献   
8.
Remotely sensing instruments, both airborne and spaceborne, of sufficient spectral resolution, can be used to identify absorptions that occur at 2.20 µm, which are indicative of AlOH minerals. In a pixel containing green and/or dry vegetation the depth of the AlOH feature at 2.20 µm is decreased. Since the depth of the feature at 2.20 µm is an indicator of the AlOH content it is desirable to correct the depth of the 2.20 µm feature in such a manner as to remove, or negate, the obscuring effect of the vegetation. This is achieved by using a multiple linear regression model where the coefficients of the linear model are produced via forward modeling, and where the independent variables are continuum removed band depth (CRBD) that are used to detect the presence of green and dry vegetation and the uncorrected AlOH CRBD. The proposed vegetation corrected continuum depth (VCCD) method was tested with synthetic datasets as well as hyperspectral data (HyMap) collected at Mount Isa in Queensland, Australia. The results of using the VCCD method on the uncorrected HyMap data were validated with vegetation free samples collected from the Mount Isa region. Improvements in the R squared statistics of the corrected 2.20 µm CRBD to the vegetation free CRBD, after application of the VCCD, were found to be 2-4 times greater than the uncorrected 2.20 µm CRBD. Visual inspection of large survey areas demonstrated that the uncorrected CRBD in vegetated areas were lower, and did not match adjacent vegetation free areas, and also produced false positives of high AlOH content.  相似文献   
9.
The nature of the optimal axial temperature distribution in a riser reactor to maximise the yield of the intermediate B, in the reaction sequence ABC was investigated by way of the selective oxidation of naphthalene to phthalic anhydride. For this case, imposition of an axial profile could not improve the yield over that obtainable by operating at the optimum isothermal temperature. This result appears to be general, and suggests that optimal yields could be obtained by operation at the optimum isothermal temperature, which should prove easier to implement in practice than a specified temperature distribution.  相似文献   
10.
Pulsed electric field (PEF) processing is a novel mild treatment for pumpable foods preservation at low or moderate temperatures. The electric field strength and the temperature distribution in the treatment chamber have been identified as the key processing parameters affecting the treatment efficacy and possibly the sensorial and nutritional quality of the food. A full 3D computational fluid dynamics (CFD) model of a pilot-scale PEF system with co-linear configuration of the electrodes was developed. The model couples the fluid dynamics and the electrical field and can be used to predict the liquid’s flow pattern, electric field distribution, temperature increase, and residence time in the treatment chamber. A total of 48 process conditions with different settings of applied voltage V, pulse length τ, pulse repetition rate (frequency) f and flow rate in combination with four different inlet temperatures were simulated for a model liquid food (NaCl solutions with two different electrical conductivities) and whole milk. The simulated PEF energy dissipated into the liquids was between 4 and 66 kJ/kg and process temperatures ranged from approximately 25 to 80 °C. The predicted temperature data agree well (R2 > 0.99) with experimental measurements in five locations of the treatment chamber using fibre optic probes.  相似文献   
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