导线测角精度超限问题的探讨

利用实例阐述了一、二级导线测量严密平差后，测角中误差超限问题，根据《规范》精度指标，分析了测角中误差超限的原因；提出一、二级导线测量严密平差后，没边、测角中误差限值的建议。     

Contribution of mantle components within juvenile lower-crust to collisional zone porphyry Cu systems in Tibet

Most porphyry Cu–Mo–Au deposits are found in magmatic arcs worldwide, and are associated with hydrous, high-fO₂, calc-alkaline magmas, derived from a mantle wedge that was metasomatized by the fluids from a subducted oceanic slab. Recently, such deposits have been documented as occurring widely in collisional settings, where they are associated with potassic magmas generated during the collisional process, but the genesis of the fertile magmas and the mechanism of metallic enrichment remain controversial. Here we present new geochemical and Sr–Nd–Hf isotopic data from the post-collisional fertile and barren porphyries of the Miocene Gangdese porphyry belt in the Tibetan orogen, an orogen formed by the collision of India and Asia in the early Cenozoic. Both types of porphyry are characterized by high K₂O contents, and have geochemical affinities with adakite, but the fertile magmas were most likely derived from the melting of a thickened juvenile mafic lower-crust, formed by the underplating of earlier asthenospheric melts at the base of crust, whereas the derivation of the barren magmas involved variable amounts of old lower-crust in Tibet. The melting of sulfide-bearing phases in the juvenile mantle components of the Tibetan lower-crust probably provided Cu, Au, and S to the fertile magmas. The breakdown of amphibole during melting at the source released the fluids necessary for the formation of the porphyry Cu deposits in Tibet. The thickened crust (up to 70–80 km), due to collision, is thought to be responsible for a decrease in the fO₂ of the fertile magmas during their ascent to the upper crust, thus preventing the generation of more porphyry Cu–Au and epithermal Au deposits in this collisional zone.     

Application of 2D numerical model to unsteady performance evaluation of vertical-axis tidal current turbine

Tidal current energy is renewable and sustainable, which is a promising alternative energy resource for the future electricity supply. The straight-bladed vertical-axis turbine is regarded as a useful tool to capture the tidal current energy especially under low-speed conditions. A 2D unsteady numerical model based on Ansys-Fluent 12.0 is established to conduct the numerical simulation, which is validated by the corresponding experimental data. For the unsteady calculations, the SST model, 2×10~5 and 0.01 s are selected as the proper turbulence model, mesh number, and time step, respectively. Detailed contours of the velocity distributions around the rotor blade foils have been provided for a flow field analysis. The tip speed ratio(TSR) determines the azimuth angle of the appearance of the torque peak, which occurs once for a blade in a single revolution. It is also found that simply increasing the incident flow velocity could not improve the turbine performance accordingly. The peaks of the averaged power and torque coefficients appear at TSRs of 2.1 and 1.8, respectively. Furthermore, several shapes of the duct augmentation are proposed to improve the turbine performance by contracting the flow path gradually from the open mouth of the duct to the rotor. The duct augmentation can significantly enhance the power and torque output. Furthermore, the elliptic shape enables the best performance of the turbine. The numerical results prove the capability of the present 2D model for the unsteady hydrodynamics and an operating performance analysis of the vertical tidal stream turbine.     

二价铁氧化对铁锰循环功能微生物活性的影响及机制

地质微生物是沉积环境中铁、锰氧化还原循环的主要驱动因子,铁锰共存环境中二价铁氧化对不同铁、锰循环功能微生物活性的影响差异和机制尚不清楚.以铁还原菌Shewanella oneidensis MR-1、铁氧化菌Pseudogulbenkiania sp.strain 2002、锰氧化菌Pseudomonas putida...     

锇粉中杂质元素分析方法研究

利用ＩＣＰ＿ＭＳ技术建立了锇粉中痕量杂质元素的分析方法。在浓ＨＮＯ３介质中,锇以ＯｓＯ４形式挥发除去,分离锇基体后,可直接测定的痕量元素达５０余种。取样量０．１ｇ,测定限为０．２～２４６ｎｇ／ｇ,可实现质量分数ｗ（Ｏｓ）为９９．９９９９％锇粉中杂质元素测定。结合ＩＣＰ＿ＡＥＳ测定Ｋ、Ｎａ、Ｃａ、Ｍｇ、Ａｌ、Ｆｅ、Ｓｉ和Ｐ,可实现锇粉原料及产品的纯度分析。     

On the Line Formation in Stellar Magnetized Atmospheres

1 INTRODUCTIONIn the previous paper (on et al. 1999, hereafter Paper I), we investigated the wavelength-dependence of four colltribution functions (CFs) derived from dmerent formal solutions andreferring to different emergellt quantities in the unpolarized case. Because one cannot generallyassign a single formation region to the whole line band in a real stellar atmosphere, e.g., the solaratmosphere, instead, the line formation region can be defined as the layers deviating farthestfrom t…     

Modeling spatially non-stationary land use/cover change in the lower Connecticut River Basin by combining geographically weighted logistic regression and the CA-Markov model

Simulating land use/cover change (LUCC) and determining its transition rules have been a focus of research for several decades. Previous studies used ordinary logistic regression (OLR) to determine transition rules in cellular automata (CA) modeling of LUCC, which often neglected the spatially non-stationary relationships between driving factors and land use/cover categories. We use an integrated geographically weighted logistic regression (GWLR) CA-Markov method to simulate LUCC from 2001–2011 over 29 towns in the Connecticut River Basin. Results are compared with those obtained from the OLR-CA-Markov method, and the sensitivity of LUCC simulated by the GWLR-CA-Markov method to the spatial non-stationarity-based suitability map is investigated. Analysis of residuals indicates better goodness of fit in model calibration for geographically weighted regression (GWR) than OLR. Coefficients of driving factors indicate that GWLR outperforms OLR in depicting the local suitability of land use/cover categories. Kappa statistics of the simulated maps indicate high agreement with observed land use/cover for both OLR-CA-Markov and GWLR-CA-Markov methods. Similarity in simulation accuracy between the methods suggests that the sensitivity of simulated LUCC to suitability inputs is low with respect to spatial non-stationarity. Therefore, this study provides critical insight on the role of spatial non-stationarity throughout the process of LUCC simulation.     

1971—2020年呼伦贝尔市积雪气候特征和未来趋势预估

利用1971—2020年呼伦贝尔市16个国家气象站最长积雪日数和最大积雪深度资料,采用经验正交函数（EOF）分析、重标极差分析（R/S）和非周期循环分析,统计最长积雪日数和最大积雪深度时间序列的Hurst指数、分维数和非周期循环的平均循环长度,分析最长积雪日数和最大积雪深度变化趋势和记忆周期;同时采用MOD10A2积雪产品,研究2001—2018年呼伦贝尔市积雪覆盖率变化。结果表明：（1）近50年呼伦贝尔市最长积雪日数呈递减趋势,最大积雪深度呈递增趋势;（2）积雪深度>20、30cm的年平均积雪日数主要出现在1996—2014年,其中积雪深度>30cm年平均积雪日数>1d;(3)呼伦贝尔市积雪初日出现在10月中旬至11月上旬,积雪终日在4月结束,积雪初日出现最早时间和积雪终日结束最晚时间都在呼伦贝尔市的北部地区;（4）R/S分析和非周期循环研究表明,呼伦贝尔市最长积雪日数和最大积雪深度H指数分别为0.589 9和0.889,即最长积雪日数未来减少和最大积雪深度未来增多趋势持续,持续时间分别为8和12 a;(5)呼伦贝尔市年平均积雪覆盖率为98.87%,呈波动增加趋势,...     

氧化铬对铝型材厂碱蚀渣制备铝方柱石材料结构的影响

利用铝型材厂碱蚀渣为主要原料,采用二步煅烧工艺制备铝方柱石材料。探索二次煅烧温度对铝型材厂碱蚀渣制备铝方柱石材料相组成、结晶度、微观结构的影响,进而研究氧化铬对铝方柱石材料相组成、微观结构的影响。采用同步热分析、X射线衍射、扫描电镜及相关分析软件表征制备的铝方柱石材料的相组成和显微结构。结果表明：铝型材厂碱蚀渣中有大量可烧失成分,物料需要进行致密化处理,再经过1500℃煅烧后的铝方柱石材料结构中具有明显的铝方柱石条柱状结构,结晶度增大,铝方柱石相对含量达到91%。随着氧化铬加入量增加,结构中的铝铬酸钙相增加。当氧化铬加入量为2%时,试样中结晶相的结晶度最高,形成条柱状铝方柱石相与立方状铝铬酸钙相共存的结构。当氧化铬加入量4%时,试样中铝方柱石相几乎消失,结晶度降低。