水流绕过二维方形障碍物的湍流数值模拟

采用了混合有限分析求解方法对湍流绕过二维方形障碍物进行了数值模拟,模拟雷诺应力项时采用了布辛涅斯克假定.采用了k-ε双层模型进行计算,通过与文献中的实验结果及数值计算结果的比较验证了本计算方法的有效性.模拟结果表明k-ε双层模型较壁面函数法预测湍流绕过方形障碍物时更为准确;障碍物高度及流动条件不变时(Re=1.4×104,H=1.0),随着方形障碍物长度的变化,障碍物上游的旋涡Ⅰ的长度基本上没有变化,而在障碍物的下游当L/H≥4时旋涡Ⅱ的长度也基本上保持不变.     

Research on characters of surrounding rock in complex geology conditions and supporting time

The methods combined by test, field monitoring and theoretical analysis were adopted to do the systemic research on the rock mass from micro-structure to macro-deformation, and rheological model of Jinchuan rock mass was established to discuss the reasonable supporting time. Resuhs show that supporting after suitable stress and displacement release can benefit for the long-term stability of surrounding rock.     

Dynamics of a qubit—TLS system under resonant microwave driving

We demonstrate the effect of different coupling strengths between a microscopic two-level system(TLS)and a microwave field on the dynamics of a qubit—TLS system when the bipartite system is subject to resonant microwave driving.Rabi beating with a different TLSmicrowave coupling strength is demonstrated in simulations.Entanglement,quantified by the concurrence between the qubit and TLS,both for pure states and mixed states,is simulated.When decoherence is considered,entanglement of the bipartite system oscillates with damping and exhibits entanglement sudden death and/or entanglement sudden death and revival.     

Numerical analysis of the two-phase pressure drop and liquid distribution in single-screw expander prototype

In this paper, the numerical simulations have been carried out to evaluate the two-phase pressure drop and liquid distribution in screw channel. The numerical models are validated against the present experimental data with statistical accuracy. The effects of pitch circle diameter （PCD）, inlet velocity and inlet sectional liquid holdup on the pressure drop and liquid distribution characteristics in the screw channel are illustrated. It is found that decreasing the PCD and increasing the inlet sectional liquid holdup can increase the liquid holdup on the outer side in screw channel. The PCD and the inlet sectional liquid holdup need to be considered in evaluating the two-phase frictional pressure drop per unit length in the screw channel. The PCD has an effect on the development of the average pressure in the various cross sections, and the inlet sectional liquid holdup has no visible impact on the changing process of the pressure drop in the screw channel. The correlation developed predicts the two-phase frictional pressure drop in the screw channel with great statistical accuracy.     

摩梭建筑艺术中的宗教禁忌与文化内涵

宗教禁忌的基本功能是确定人们在认识上和社会生活与交往中一些不可逾越的界限,将人类文化与生活纳入有序的制度化模式之中.这种功能影响到了摩梭人的生活方式与造物理念,同时也清晰的反映在他们房屋构建的时间与空间的划分上.这种划分并不是一种纯粹物理性质的划分,而是有着明显的文化内涵.摩梭人不仅为了栖身而分割空间,更要赋予房屋建筑以意义.     

建党百年 湖南科技创新发展历程研究

2021年是中国共产党建党100周年,这100年来,科技创新给湖南带来的荣耀历历在目、带来的启示也更加清晰,湖南正努力向着由国家重要影响力的科技创新大省向科技创新强省转变的宏伟目标砥砺前行,助力科技强国建设.文章以建党百年为契机,梳理了湖南科技在4个不同历史阶段具有的特点及创新发展取得的一系列重大成就,借以激励所有科技工作者在助推科技创新高质量发展的道路上奋勇向前,为科技创新谱写新的篇章,迈向更广阔的征程.     

SBR系统反硝化过程中COD与TN关系

SBR是序批式活性污泥法的简称, SBR系统行运行模式不同,脱氮除磷效果会发生变化。SBR系统氨氮硝化过程在好氧阶段进行,脱氮过程主要在缺氧阶段进行。除少数细菌能进行自养反硝化,大部分反硝化细菌进行反硝化都是进行异养反硝化。经研究发现SBR运行过程中TN浓度和COD浓度具有相关性,COD和TN浓度之间存在三阶函数关系,本实验反硝化速率为1.2mg/L。     

Satellite-derived surface water pCO2 and air-sea CO2 fluxes in the northern South China Sea in summer

An empirical approach is presented for the estimation of the partial pressure of carbon dioxide (pCO2) and air-sea CO2 fluxes in the northern South China Sea in summer using satellite-derived sea surface temperatures (SSTs), chlorophyll-a (Chl a) concentrations, and wind fields. Two algorithms were tested. The first used an SST-dependent equation, and the other involved the introduction of Chl a. Regression equations were developed for summer based on in situ data obtained in July, 2004. Using the monthly average SST and Chl a fields derived from the advanced very high resolution radiometer (AVHRR) and the SeaWiFS (sea-viewing wide field of view sen-sor), respectively, the monthly pCO2 fields were computed. The derived pCO2 was compared with the shipboard pCO2 observations con-ducted in July, 2000. This resulted in a root-mean-square error of 4.6 μatm, suggesting that the satellite-derived pCO2 was in general agreement with the in situ observations. The air-sea CO2 flux was further computed with the aid of the monthly mean QuikSCAT wind speed. We contend that more shipboard data are necessary for refining the empirical algorithms and reducing the uncertainty in the results.     

Research on methods of designing and building digital seabed database

With a review of the recent development in digitalization and application of seabed data, this paper systematically proposed methods for integrating seabed data by analyzing its feature based on ORACLE database management system and advanced techniques of spatial data management. We did research on storage structure of seabed data, distributed-integrated database system, standardized spatial database and seabed metadata management system in order to effectively manage and use these seabed information in practical application. Finally, we applied the methods researched and proposed in this paper to build the Bohai Sea engineering geology database that stores engineering geology data and other seabed information from the Bohai Sea area. As a result, the Bohai Sea engineering geology database can effectively integrate huge amount of distributed and complicated seabed data to meet the practical requisition of Bohai Sea engineering geology environment exploration and exploitation.     

石墨烯/铜-银合金复合膜修饰玻碳电极同时测定鸟嘌呤和腺嘌呤

采用简单的搅拌还原法制备了石墨烯/铜-银合金纳米复合物,基于该复合物修饰玻碳电极制备了新型的电化学传感器.用SEM和TEM扫描电镜对石墨烯和石墨烯/铜-银合金纳米复合物进行了表征.分别用循环伏安法和差分脉冲伏安法研究了鸟嘌呤和腺嘌呤在修饰电极上的电化学行为.结果表明,石墨烯/铜-银合金纳米复合膜显著促进了鸟嘌呤和腺嘌呤在电极上的电子传递速度.在0.1 mol/L醋酸盐缓冲溶液(ABS)中(pH 4.5),鸟嘌呤和腺嘌呤在该修饰电极上具有良好的电化学行为,鸟嘌呤和腺嘌呤分别在1.0¹00.0μmol/L浓度范围内,信号线性关系良好,相关系数分别为0.997和0.998.鸟嘌呤和腺嘌呤的检出限分别为6.0×10-8mol/L和5.0×10-8mol/L(S/N=3).将该传感器用于DNA样品中嘌呤碱基分析,得到(G+C)/(A+T)的比值为0.79.