Metrics to identify meaningful downscaling skill in WRF simulations of intense rainfall events

Dynamical downscaling attempts to provide regional detail to climate change projections that subsequently can be used as input to climate change impact models. However, unlike forecasts by numerical weather prediction models, downscaled projections cannot be tested for skill because the future of interest is decades away. Nevertheless, models can be tested in terms of how well they simulate current weather or climate, thus giving an indication of skill in representing the process of interest. Here, six configurations using different combinations of three microphysics and two planetary boundary layer schemes are assessed on their skill to simulate desired characteristics in daily rainfall fields from three two week simulations in southeast Australia; ‘desired’ meaning desirable in relation to the intended application. Of different metrics and analysis assessed, a metric based on variography analysis, summarising characteristics about spatial variability and dissimilarity, is shown to provide the most informative guidance relative to the desirable characteristics.     

动压巷道组合锚索的“应力柱”效应研究

为有效控制动压巷道围岩变形较大、支护控制困难等问题，以山西某矿8102工作面为工程背景，通过现场调研、数值模拟、现场试验等手段，对动载扰动条件下组合锚索的支护效果进行研究分析，并在现场进行了工业性试验。研究结果表明:通过对在动压巷道顶板施加组合锚索的数值模拟得知，巷道顶板应力比较集中，并出现“应力柱”效应，巷道变形较小。结合现场工业性试验，在动压巷道顶板施加组合锚索，巷道变形破坏情况明显好于未施加组合锚索段；组合锚索可以有效控制动压巷道围岩变形破坏情况。     

Global modeling of hydrogen using GFDL-AM4.1: Sensitivity of soil removal and radiative forcing

Hydrogen (H₂) has been proposed as an alternative energy carrier to reduce the carbon footprint and associated radiative forcing of the current energy system. Here, we describe the representation of H₂ in the GFDL-AM4.1 model including updated emission inventories and improved representation of H₂ soil removal, the dominant sink of H₂. The model best captures the overall distribution of surface H₂, including regional contrasts between climate zones, when v_d(H₂) is modulated by soil moisture, temperature, and soil carbon content. We estimate that the soil removal of H₂ increases with warming (2–4% per K), with large uncertainties stemming from different regional response of soil moisture and soil carbon. We estimate that H₂ causes an indirect radiative forcing of 0.84 mW m^?2/(Tg(H₂)yr^?1) or 0.13 mW m^?2 ppbv^?1, primarily due to increasing CH₄ lifetime and stratospheric water vapor production.     

Nonlinear analysis of cable structures using the dynamic relaxation method

The analysis of cable structures is one of the most challenging problems for civil and mechanical engineers. Because they have highly nonlinear behavior, it is difficult to find solutions to these problems. Thus far, different assumptions and methods have been proposed to solve such structures. The dynamic relaxation method (DRM) is an explicit procedure for analyzing these types of structures. To utilize this scheme, investigators have suggested various stiffness matrices for a cable element. In this study, the efficiency and suitability of six well-known proposed matrices are assessed using the DRM. To achieve this goal, 16 numerical examples and two criteria, namely, the number of iterations and the analysis time, are employed. Based on a comprehensive comparison, the methods are ranked according to the two criteria. The numerical findings clearly reveal the best techniques. Moreover, a variety of benchmark problems are suggested by the authors for future studies of cable structures.     

刚性索动力学系统的约化与索力测量

为解决索力动测中弯曲刚度的耦合影响问题，研究刚性索动力学系统的约化及相应的索力算法。对系统时间和空间进行坐标缩放，建立新时空坐标体系，使原方程约化为最简形式——所有系数均为1或-1，得到频率比互等关系；求解新坐标下的动力学方程，导出固支条件下的频率方程，分析其频率-梁长和频率比-梁长函数特性，提出基于频率比互等关系的双频式索力算法。给出两组10个算例均与现有文献吻合良好。研究表明：系统频率在新坐标下仅由单一参数决定；双频式算法可将索力测量的双参数反问题转化为单参数反问题，实现对索力和弯曲刚度的解耦；与其他方法相比，该方法有两个特点：①两个无量纲参数均具有明确的意义，便于工程人员掌握；②参数区间不受限，不需要对参数区间进行预判或近似处理。     

动态循环荷载下大坝混凝土拉压转换损伤本构模型构建及影响研究

目前混凝土坝抗震安全评价中,对于动态循环荷载下大坝混凝土损伤本构模型中从受拉状态向受压状态转变过程(拉压转换)中的混凝土弹性模量变化,一般都基于商用软件ABAQUS的"单边效应"假设,认为混凝土弹性模量立即恢复为初始弹性模量。上述假设的合理性缺乏试验验证,直接影响混凝土坝抗震安全评价的可靠性。通过对全级配大坝混凝土拉压转换全过程试验成果的观察分析,发现混凝土从受拉状态进入受压状态后弹性模量并非立即恢复为初始弹性模量,而是由损伤后弹性模量连续渐进恢复至初始弹性模量,期间原有的受拉残余应变在压应力作用下迅速减小到较小数值,因此ABAQUS的"单边效应"假设并不符合实际情况。本文以全级配大坝混凝土拉压转换全过程试验成果为基础,提出受拉损伤发生后,拉压转换时受压应力应变关系采用双折线模型的思路,据此推导了相应的应力-应变关系解析表达式,构建了更接近混凝土拉压转换时真实状况的本构关系数值模型。通过实际工程的计算分析,发现常用的受压弹性模量立即恢复为初始弹性模量的损伤本构模型过高估计了坝体刚度,可能带来偏于不安全的评价结果。     

Mechanical properties of continuous bamboo fiber-reinforced biobased polyamide 11 composites

This study is devoted to the analysis of the properties of continuous bamboo fiber (BF)-reinforced polyamide 11 (PA 11) composites. The SEM observations highlighted continuity between BFs and the polymeric matrix showing a high density of hydrogen bonds. The comparative calorimetric study of the matrix and its composites showed that the crystallinity of PA 11 was not modified by the presence of bamboo fibers. The physical aging observed in PA 11 is no more observed in composites due to physical interactions between PA 11 and BFs. The mechanical properties were investigated by tensile strength and dynamic mechanical analysis. The introduction of BFs enhanced Young's modulus of the matrix by a factor of 10. The presence of BFs also improved the storage shear modulus G′ over the whole temperature range. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47623.     

NMR-Guided Repositioning of Non-Steroidal Anti-Inflammatory Drugs into Tight Junction Modulators

Bioavailability is a major bottleneck in the clinical application of medium molecular weight therapeutics, including protein and peptide drugs. Paracellular transport of these molecules is hampered by intercellular tight junction (TJ) complexes. Therefore, safe chemical regulators for TJ loosening are desired. Here, we showed a potential application of select non-steroidal anti-inflammatory drugs (NSAIDs) as TJ modulators. Based on our previous observation that diclofenac and flufenamic acid directly bound various PDZ domains with a broad specificity, we applied solution nuclear magnetic resonance techniques to examine the interaction of other NSAIDs and the first PDZ domain (PDZ1) of zonula occludens (ZO)-1, ZO-1(PDZ1). Inhibition of ZO-1(PDZ1) is expected to provide loosening of the epithelial barrier function because the domain plays a crucial role in maintaining TJ integrity. Accordingly, diclofenac and indomethacin were found to decrease the subcellular localization of claudin (CLD)-2 but not occludin and ZO-1 at the apicolateral intercellular compartment of Madin–Darby canine kidney (MDCK) II cells. These NSAIDs exhibited 125–155% improved paracellular efflux of fluorescein isothiocyanate insulin for the Caco-2 cell monolayer. We propose that these NSAIDs can be repurposed as drug absorption enhancers for peptide drugs.     

Investigation of non-isothermal crystallization,dynamic mechanical and dielectric properties of poly(ether-ketone) matrix composites

ABSTRACT

Poly(ether-ketone)/hexagonal boron nitride (h-BN) composites reinforced with micrometer-sized h-BN particles were investigated. The composites exhibited glass transition temperature (T_g) and thermal stability over 160°C and 560°C, respectively. The melting point and peak crystallization temperatures of the composites decreased up to 17°C and 12°C, respectively. The linear CTE of the composites decreased both below and above the T_g. The storage modulus increased with increasing h-BN content at all temperatures (50–250°C). The composites possessed excellent dielectric properties with insignificant dispersion with increasing frequency. Thus, resultant composites are promising candidates for the printed circuit boards/electronic substrates.     

隧道洞口上方危岩崩塌块石运动规律及其对隧道的危害

为揭示危岩崩塌块石的运动规律及其对下方隧道洞口的危害,以都香高速昭通段乐红隧道洞口高陡边坡危岩区崩塌体为研究对象,运用理论计算与Rockfall数值计算2种形式对危岩区崩塌体失稳后块石的运动特征进行预测,运用Abaqus有限元软件模拟不同初速度、不同冲击落点下块石冲击隧道结构的动力响应,揭示不同因素对块石冲击隧道结构的影响程度.结果 显示:理论计算与Rockfall数值计算结果吻合,崩塌块石经坠落、碰撞、滚动最终会与隧道引洞段上表面发生碰撞;与冲击落点相比,块石初速度对隧道结构的动力响应特性影响更大;块石冲击落点位于隧道圆拱圆心正上方位置时对隧道结构的损伤最大;不同冲击落点对碰撞回弹后块石的速度影响不大.