Paleoenvironmental implications of new OSL dates on the formation of the “Shell Bar” in the Qaidam Basin,northeastern Qinghai-Tibetan Plateau

A geological feature in the Qaidam Basin known as the “Shell Bar” contains millions of freshwater clam shells buried in situ. Since the 1980s, this feature in the now hyper-arid basin has been interpreted to be lake deposits that provide evidence for a warmer and more humid climate than present during late marine isotope stage 3 (MIS 3). Global climate during late MIS 3 and the last glacial maximum, however, was cold and dry, with much lower sea levels. We re-investigated the feature geomorphologically and sedimentologically, and employed optically stimulated luminescence (OSL) dating to verify the chronology of the sediments. We interpret the Shell Bar to be a remnant of a river channel formed by a stream that ran across an exposed lake bed during a regressive lake phase. Deflation of the surrounding older, fine-grained lacustrine deposits has left the fluvial channel sediments topographically inverted, indicating the erosive nature of the landscape. Luminescence ages place the formation of the Shell Bar in MIS 5 (~113–99 ka), much older than previous radiocarbon ages of <40 ka BP, but place the paleoclimatic inferences more in accord with other regional and global climate proxy records. We present a brief review of the age differences derived from ¹⁴C and OSL dating of some critical sections that were thought to represent a warmer and more humid climate than present during late MIS 3. We attribute the differences to underestimation of ¹⁴C ages. We suggest that ¹⁴C ages older than ~25 ka BP may require re-investigation, especially dates on samples from arid regions.     

Six-Degree-of-Freedom Measurement of Plate Anchors in Centrifuge by Magnetometers

China Ocean Engineering - The six-degree-of-freedom movement of an offshore plate anchor is essential to evaluate anchor performance. As an emerging technology, magnetometer has shown its potential...     

基于一测多评法的半夏碱基和核苷含量测定

目的：采用高效液相色谱法（HPLC）建立半夏中2种碱基（尿嘧啶、次黄嘌呤）和3种核苷（尿苷、鸟苷、胸苷）的定量检测方法,以验证该方法在半夏质量控制中应用的可行性和技术适应性。方法：超声提取半夏粉末,采用HPLC法检测尿嘧啶、次黄嘌呤、尿苷、鸟苷、胸苷的含量。使用Agilent ZORBAX SB-C¹⁸色谱柱（4.6 mm×250 mm,5μm）,以水-甲醇为流动相,流速0.8 ml/min,检测波长260 nm,柱温30℃,进样量10μl,梯度洗脱（0～7 min,2%～2%甲醇;7.1～13 min,3%～3%甲醇;13～25 min,3%～20%甲醇;25～40 min,20%～98%甲醇）。以鸟苷为内参物,建立尿嘧啶、次黄嘌呤、尿苷、胸苷相对于鸟苷的相对校正因子,并进行含量计算,实现一测多评。同时采用外标法测定10批半夏药材中5种成分的含量,比较计算值与实测值的差异,验证一测多评的准确性。结果：此种方法建立的相对校正因子在不同仪器中的耐用性良好。计算值与实测值之间无显著性差异（RSD<1.3%）。结论：本研究建立的半夏中5种成分同时测定的一测多评法,简单易行,成本较低,可为后续物质基础及作用机制研究提供借鉴。     

Dynamic data-driven railway bridge construction knowledge graph update method

Effectively integrating and correlating multisource data involved in the bridge construction process is crucial for the improvement of the bridge informatization level. In the current issues of dynamic numerous data and low information sharing between different engineering departments, the traditional information management methods are inefficient in providing comprehensive and accurate data support for construction safety. Focusing on the bridge construction stage, this article proposes a dynamic data-driven construction method of railway bridge construction knowledge graph (KG) in combination with dynamic data (materials, personnel, equipment and sensors) in the construction process and KG technology. By taking a railway bridge as a case, the study develops a prototype system and analyzes the effectiveness of bridge construction KG in material traceability, personnel and equipment management and construction safety guidance, which can provide comprehensive and accurate data support for bridge construction management and construction optimization. The results show that: (1) bridge construction KG that takes into account the dynamic features of bridge projects can effectively integrate multiple elements; (2) the bridge construction KG is dynamically updated through real-time comparison and advance prediction based on the dynamic data collected by multi-sensing equipment at the construction site, and can provide effective data support for guiding bridge construction safety; and (3) the construction management prototype system based on railway bridge construction KG can provide accurate data support for material traceability, personnel and equipment management and assisted risk event decision-making. The results of the comparative experiment between the KG group and the spreadsheet group showed that utilizing the KG saved approximately 50% of time and achieved a 20% higher accuracy rate in the material traceability task compared to the spreadsheet group. In general, this study proposes a dynamic data-driven construction method of railway bridge construction KG, which can effectively realize the effective integration and management of multisource data in the bridge construction process, provide the necessary scientific basis for fine bridge management, and help to improve bridge informatization management level.     

Geographic range size patterns across plants and animals of Xinjiang,China

Patterns in species geographic range size are relatively well-known for vertebrates,but still poorly known for plants.Contrasts of these patterns between groups have rarely been investigated.With a detailed flora and fauna distribution database of Xinjiang,China,we used regression methods,redundancy analysis and random forests to explore the relationship of environment and body size with the geographic range size of plants,mammals and birds in Xinjiang and contrast these patterns between plants and animals.We found positive correlations between species range size and body size.The range size of plants was more influenced by water variables,while that of mammals and birds was largely influenced by temperature variables.The productivity variable,i.e.,Enhanced Vegetation Index(EVI)was far more correlated with range size than climatic variables for both plants and animals,suggesting that vegetation productivity inferred from remote sensing data may be a good predictor of species range size for both plants and animals.     

The earliest well-dated archeological site in the hyper-arid Tarim Basin and its implications for prehistoric human migration and climatic change

The routes and timing of human occupation of the Tibetan Plateau (TP) are crucial for understanding the evolution of Tibetan populations and associated paleoclimatic conditions. Many archeological sites have been found in/around the Tarim Basin, on the northern margin of the Tibetan Plateau. Unfortunately, most of these sites are surface sites and cannot be directly dated. Their ages can only be estimated based on imprecise artifact comparisons. We recently found and dated an archeological site on a terrace along the Keriya River. Our ages indicate that the site was occupied at ~ 7.0–7.6 ka, making it the earliest well-dated archeological site yet identified in the Tarim Basin. This suggests that early human foragers migrated into this region prior to ~ 7.0–7.6 ka during the early to mid-Holocene climatic optimum, which may have provided the impetus for populating the region. We hypothesize that the Keriya River, together with the other rivers originating from the TP, may have served as access routes onto the TP for early human foragers. These rivers may also have served as stepping stones for migration further west into the now hyper-arid regions of the Tarim Basin, leading ultimately to the development of the Silk Road.     

Experimental and theoretical investigations on high-pressure phase transition of Sr2Fe2O5

Sr₂Fe₂O₅ is a typical oxygen-deficient perovskite and adopts brownmillerite phase (Ibm2, Z = 4) at ambient conditions. Its high-pressure structural behavior has been investigated by both synchrotron radiation X-ray diffraction with diamond anvil cell technique and first principles calculations. Experimental results clearly show that the brownmillerite Sr₂Fe₂O₅ transforms into a tetragonal perovskite-type phase at 12.0 GPa and room temperature, and then into a Sr₂Mn₂O₅-type phase (Pbam, Z = 2) at 23.3 GPa after high-temperature annealing. The Sr₂Mn₂O₅-type phase is stable up to at least 60 GPa and it further undergoes a reversible transition to a lower symmetry phase at 79.1 GPa and ~2,000 K. The results from theoretical calculation not only confirm that the tetragonal phase of Sr₂Fe₂O₅ is isostructural with the high-temperature structure of Ba₂In₂O₅ (I4/mcm, Z = 4), but also predict a series of phase transitions from brownmillerite phase to Ba₂In₂O₅-type phase at 6.9 GPa, and then to Sr₂Mn₂O₅-type phase at 19.7 GPa, which coincides with present experiment results. Isothermal pressure–volume relationship of the Sr₂Mn₂O₅-type phase can be well described by the Birch–Murnaghan Equation of State with V ₀ = 111.6(10) ų, B ₀ = 122(9) GPa, B ₀ ^′  = 4(fixed) experimentally and V ₀ = 115.8(3) ų, B ₀ = 92(4) GPa, B ₀ ^′  = 4(fixed) theoretically. The transition mechanism from brownmillerite to Ba₂In₂O₅-type phase is the displacement of four-coordinated Fe³⁺ ions to higher coordinated positions upon compression. In addition, a semiconductor-to-metal crossover is predicted from brownmillerite to Ba₂In₂O₅-type or Sr₂Mn₂O₅-type phase.     

山东济宁三号煤矿上组煤水文地质条件分析

济宁三号煤矿目前开采的煤层为上组煤的3煤(3上、3下煤),自投产以来,发生多次涌水,如13下01综放面侏罗系底部含水层最大涌水量达533.84m3/h,63下01综放3煤顶板砂岩最大涌水量527m3/h,曾一度出现工作面局部被淹而导致停产,对矿井的安全高效生产构成了极大的威胁。在综合分析研究上组煤顶板各含水层的水文地质特征和充水条件的基础上,认为上组煤(3上、3下煤)开采时的直接充水水源为3煤顶板砂岩含水层;间接充水水源是侏罗系含水层水以及局部地区对侏罗系含水层起补给作用的第四系含水层;部分地区侏罗系含水层被采动裂隙导通而成为直接充水水源,大部分地段第四系底部均为粘土,有效的阻隔了第四系与下伏侏罗系含水层的水力联系,对下伏含水层补给微弱;充水通道主要有断层、采动裂隙、封闭不良钻孔和破坏的井筒。为指导下一步煤矿生产预防水害事故提供了依据。     

Numerical analysis for cooling effect of open boundary ripped-rock embankment on Qinghai-Tibetan railway

At present, the Qinghai-Tibetan railway is being built, and it will pass across more than 550-km perma-frost regions. Therefore, the key to the stability of therailway embankment lies in solving the permafrost problem. Because global warming and existence of railway tend to degrade the permafrost in these re-gions[1], more difficulties and problems are induced in the construction and maintenance of railway. In the area where the mean annual air temperature is higher than a certain value, the …     

一种基于三维激光点云建模的技术方案

随着数字化城市建设的推进,大规模建筑物需要完成三维模型的工作,传统根据全站仪采集数据制作模型的方法效率低下,特别是针对复杂建筑、煤化厂、炼化厂等厂区装置进行建模,显得更加困难。本文提出了利用三维激光仪扫描点云数据进行三维建模的方案,可以大大缩短外业数据采集的时间,减少外业工作量。