三门峡原状黄土的大型直剪试验及其尺寸效应

三门峡原状黄土富含大孔隙且垂直节理较为发育,在工程实践中对其本身的抗剪强度及变形特性有着重要影响。以往的黄土强度和变形试验多数采用常规直剪试验,导致试样避开了多数节理面和大孔隙,使试样的整体代表性降低。通过对三门峡原状黄土进行一系列的大型直剪试验,并结合常规直剪试验分析了原状黄土抗剪强度的尺寸效应。试验结果表明:关于试样的剪应力-剪切位移关系曲线,在50、100 kPa垂直压力下呈现剪切软化现象,而在200、300 kPa垂直压力下呈现剪切硬化现象;在相同垂直压力条件下,大型直剪试验得出的试样抗剪强度低于常规直剪试验得到的,并且这种差异随着垂直压力的增大逐渐变得显著。工程实践中应充分考虑尺寸效应对黄土抗剪强度的影响,进一步提升工程的安全性。     

水电站大坝运行安全巡视检查在线管理的探索与实践

巡视检查是掌握大坝运行安全状况的重要手段.研究并建立了大坝运行安全巡视检查信息报送及管理模式,检查和监督电力企业巡视检查工作的过程和质量控制,及时了解巡视检查发现的结构异常状况,建立综合巡视检查结果和仪器监测数据的在线结构安全评判系统,以及异常情况的技术会商方式,全面掌握大坝安全状态.     

Graphene oxide as a water transporter promoting germination of plants in soil

Graphene oxide (GO) is a graphene derivative bearing various oxygen-containing functional groups attached to the basal plane and to the edges of the graphene lattice and hence has a unique structure in which numerous hydrophobic sp² clusters are isolated within the hydrophilic sp³ C–O matrix. In this study, the hydrophilic nature and water-transporting properties of GO were exploited to promote germination and growth of plants. It was found that a low dose of GO significantly promoted the germination of spinach and chive in soil. The oxygen-containing functional groups of GO collected water, and the hydrophobic sp² domains transported water to the seeds to accelerate the germination of plants. The strong interaction between GO and the surfaces of soil grains stabilized GO in the soil and prevented dissipation of GO. In addition, no GO was detected either on the surface or inside the cells of plants; this finding confirmed that GO was not phytotoxic. Therefore, GO may serve as a promising nontoxic additive to increase a plant yield.

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基于并行计算的电压暂降仿真分析技术研究

评估地区电网电压暂降风险对于保障用户电力可靠供应至关重要,当前使用电力系统综合分析程序(PSASP)进行区域电网电压暂降仿真时存在仿真效率低、耗时长等问题,因此,提出一种基于并行计算的电压暂降仿真分析方法,使用PSASP软件能快速评估地区电网各母线节点的电压暂降严重程度,为治理地区电网电压暂降问题提供重要的技术手段。实际应用表明,本文所提方法能有效解决大型电网电压暂降仿真效率问题,为暂降治理提供决策支撑。     

Mechanism of Desulfurization from Liquid Iron by Hydrogen Plasma Arc Melting

In this study, desulfurization from liquid iron by Ar and (10 to 40 pct)H₂?+?Ar plasma arc melting (HPAM) was examined. The experimental results show that the rate of desulfurization increases as hydrogen is added proportionally to plasma gas. The thermodynamic analysis suggests that the interaction of activated atomic hydrogen and dissolved sulfur in liquid iron, \( \left[ {\text{S}} \right] + 2{\text{H}} = {\text{H}}_{ 2} {\text{S}}, \) could be taking place. The kinetic analysis confirms that the desulfurization from liquid iron obeys a first-order rate law.     

基于两种仿生算法的低碳主动配电网规划

分布式电源（DG）为未来配电网的规划问题带来了许多新的挑战。在传统配电网规划基本要求的基础上,结合主动配电网相关标准,对主动配电网进行了新的规划。规划过程中,将选择投入运行的电网网架和分布式电源出力大小作为优化变量,将电网的碳排放环境成本作为评判标准。以14节点网络系统为例,将遗传算法（GA）和布谷鸟搜索（CS）算法相结合,并根据电网规划实际情况对算法做了改进。最终在MATLAB环境下,结合MATPOWER潮流计算工具,实现了主动配电网的低碳规划。算例结果表明,该规划方法简单有效,能够为低碳经济下主动配电网的进一步发展提供参考和依据。     

核酸标准物质的研究进展

核酸是遗传信息的载体,随着以核酸扩增为基础的体外诊断技术的快速发展,核酸检测被广泛应用于医学诊断、法医鉴定、进出口检验检疫以及物种进化研究等领域。核酸标准物质是保证核酸检测结果准确性和溯源性的“金标准”,WHO和我国国家市场监督管理总局均规定,体外诊断试剂需使用国际、国家标准物质或厂级标准品对其准确性进行溯源。HER2、BRAF、EGFR等基因突变致癌机制的解析促使曲妥珠单抗、威罗菲尼、美罗华等一系列靶向治疗药物上市,导致我国核酸标准物质面临很大缺口。由于核酸具有结构复杂、易降解和分子量大等特点,难以满足均匀性和稳定性要求,因此核酸标准物质的研制进展缓慢。本文对核酸标准物质的制备方法及国内外研究进展进行简要综述,为高效研制体外诊断用核酸标准物质提供参考。     

3钉带衬套复合材料/金属接头拉伸疲劳性能试验研究

带衬套沉头螺栓连接已经在复合材料连接结构中得到了一定的应用,需要对其疲劳性能进行研究.本研究对一种单搭接3钉带衬套碳纤维复合材料/钛合金沉头螺栓连接接头进行了静态拉伸试验,测量了接头的载荷-位移曲线、拉伸极限强度与条件挤压强度.在此基础上,确定67％接头极限载荷为拉伸疲劳最大载荷,按应力比为0.1的循环载荷对接头进行疲劳试验,并与对应的无衬套接头进行了对比,研究了衬套对该接头疲劳性能的影响.结果表明,衬套的引入改善了应力分布情况,使结构疲劳寿命延长了98.4％.同时,静态拉伸试验中发生层合板的钉孔挤压以及净截面拉伸破坏,疲劳试验中发生钛合金板的拉伸疲劳破坏,部分无衬套接头还发生了螺栓疲劳破坏.经分析发现,两类材料的疲劳性能表现差异较大,复合材料/金属机械连接接头的疲劳破坏模式会因载荷水平的不同而发生变化,在低于一定载荷水平下容易出现金属结构的破坏.     

Nanogels of poly-N-isopropylacrylamide,poly-N,N-diethylacrylamide and acrylic acid for controlled release of thymol

Synthesis of new nanogels composed of poly N-isopropylacrylamide (PNIPAM) and poly N,N-diethylacrylamide (PNDEA) at different mole ratios of 100:0–50:50 were performed with constant acrylic acid (AA) content (NIPAM:AA mole ratio of 10:1) by free radical polymerization. The obtained nanogels were loaded with thymol and self-assembled on the surface of chitosan films to evaluate control release of the antimicrobial. The effect of temperature (8–35 °C), pH (2–8), and ions were evaluated on particle size (100–200 nm) and charge (?25--40 mv). With the increasing ratio of PNDEA in the copolymers, the lower critical solution temperature shifted gradually from 33 °C to <10 °C. When pH value decreased from 8 to 2, nanogel shrink occurred. Different ions influenced the hydrodynamic diameters of particles, causing salting out effect that followed the order of Hofmeister series. Thymol loaded within mole ratios of 50:50 of NIPAM/NDEA nanogels had longer release time (>24 h) at 4 °C than that at 25 °C (around 6 h). All thymol loaded nanogels exhibited antimicrobial activity against E. coli and B. subtilis.