Estimation of Vertical Floor Displacement Using a Wavelet De-Noising Method

The horizontal response of structural and nonstructural systems during seismic events has been studied for a long time. However, the effect of the vertical response of floors on building contents and nonstructural systems has still remained a topic of concern. A wavelet de-noising method along with the experimental data obtained from a full-scale test at E-Defense is used to estimate the vertical floor displacement of a five-story steel moment frame building in base-isolated and fixed-base configurations. Vertical displacements of slabs and beams are calculated from the experimental data and formulated based on their out-of-plane dominant frequencies. A curve fitting approach is then carried out to estimate vertical displacements at floors and stories. In these tests, partition wall damage such as buckling of studs occurred at slab displacements of about 1 in.     

Assessment of Numerical and Experimental Errors in Hybrid Simulation of Framed Structural Systems through Collapse

Hybrid simulation can provide significant advantages for large-scale experimental investigations of the seismic response of structures through collapse, particularly when considering cost and safety of conventional shake table tests. Hybrid simulation, however, has its own challenges and special attention must be paid to mitigate potential numerical and experimental errors that can propagate throughout the simulation. Several case studies are presented here to gain insight into the factors influencing the accuracy and stability of hybrid simulation from the linear-elastic response range through collapse. The hybrid simulations were conducted on a four-story two-bay moment frame with various substructuring configurations. Importantly, the structural system examined here was previously tested on a shake table with the same loading sequence, allowing for direct evaluation of the hybrid simulation results. The sources of error examined include: (1) computational stability in numerical substructure; (2) setup and installation of the physical specimen representing the experimental substructure; and (3) the accuracy of the selected substructuring technique that handles the boundary conditions and continuous exchange of data between the subassemblies. Recommendations are made regarding the effective mitigation of the various sources of errors. It is shown that by controlling errors, hybrid simulation can provide reliable results for collapse simulation by comparison to shake table testing.     

Guidelines for Authors

Though known primarily for his work on muscle energetics, Archibald Vivian Hill, as discussed below, also made important scientific and pedagogic contributions to nerve physiology.     

Experimental examination of animal trampling effects on artifact movement in dry and water saturated substrates: a test case from South India

This paper presents the motivation, procedures, and results of an experiment that examines short episodes of animal trampling in dry and water saturated substrates in South India. While horizontal artifact displacement was similar to that modeled by other trampling experiments, vertical artifact displacement in water saturated substrates was greater than any reported experiment to date. The toolstone used in this experiment, a silicious limestone, exhibited minimal damage after trampling. Artifact inclination patterning appeared to be a potentially diagnostic middle-range marker of trampling in water saturated substrates. Given the abundant number of Paleolithic sites that are located on flat, open surfaces near water-bodies, or experience monsoonal climatic regimes, we propose that future excavations should measure artifact inclination on a regular basis.     

Characterization of a current coprogenic sample originated by Canis lupus as a tool for identifying a taphonomic agent

We study a skeletal sample digested by Iberian wolf (Canis lupus signatus) in order to finding diagnostic features of digestion caused by this agent. The remains were taken from scats collected in different natural areas in the northwestern Iberian Peninsula. We tested different methods to recover the remains with the goal of not produce biases, and we evaluated the most appropriate methods. The results were compared with those reported by other authors who have also worked with samples digested by wolves. Bias during the procurement of the skeletal assemblages seems to be a significant cause of the differences observed between the samples. We found that it was necessary to fully recover all remains and individually analyze all modifications, even in small-sized remains. Taphonomic characterization was performed by analyzing physical and biochemical modifications. We believe that these results may be useful in the study of archaeological and paleontological assemblages.     

Study of the Impact of Urban Development on Surface Temperature Using Remote Sensing in Ho Chi Minh City,Southern Vietnam

Rapid urbanisation and industrialisation have resulted in sharp land cover changes. Urban change not only impacts on land cover but also on urban climate. Land surface and atmospheric modifications due to urbanisation generally lead to a modified thermal climate that is warmer than the surrounding, non-urbanised areas. In this research remote sensing technology was used to evaluate urban growth patterns and its thermal characteristics through mapping impervious surfaces and evaluating thermal infrared images. The case study was carried out in the northern part of Ho Chi Minh City, which has experienced accelerated urban development since the late 1980s. Landsat and Aster images were used to calculate variations in urban impervious surfaces from 1989 to 2006. Thermal bands were processed to obtain radiant surface temperatures for investigating the urban heat island effect associated with increasing impervious surfaces, both spatially and temporally. Impacts of urban development on surface temperature were shown by investigating the surface urban heat island effect intensity. The results show that the built-up area in the northern part of Ho Chi Minh City expanded by 6.5 times between 1989 and 2006. Urban development has altered the magnitude and pattern of the surface urban heat island, with the highest land surface temperature cores found in the industrial (greater than 45^oC) and urban areas (within 36^oC and 40^oC). In suburban and rural areas, where agricultural land still remains with full vegetation cover, the land surface temperature is usually lower. Using remote sensing, the impervious surface was extracted with overall accuracy and a Kappa coefficient for all three years greater than 96%, and the retrieved land surface temperatures with variations from in-situ measurements of less than 2^oC. The results presented here indicate that remote sensing can help to spatially monitor urban development and land surface temperature changes over the whole area and over a long period of time.     

陈列银币变色原因初步分析

为了探讨博物馆内陈列银币经常出现的表面失去光泽甚至变暗变黑的原因,采用离子色谱、X荧光光谱等方法分析变色银币清洗液成分,并对博物馆周边环境空气和颗粒物进行检测。结果表明,Cl-、NO2-、NO3-、SO42-等无机离子主要来源于环境空气,甲酸和乙酸主要来源于陈列用装饰材料。采用电子能谱、扫描电镜等分析手段对银试片表面黑色物质进行分析,发现其主要元素为碳、氧、硫,其中硫分布较深,说明黑色物质除了硫化物外还存在氧化物;进一步采用红外光谱分析发现,发黑处有明显的碳氢吸收,说明发黑银试片表面除了无机物外还存在含碳有机物,可解释扫描电镜和电子能谱中检测到碳的原因。通过模拟实验比较了空气质量、相对湿度、光源和光照等因素对银变色所起作用表明,在空气质量较差的情况下,光照强度差异几乎与银变色程度无关。在标准空气中相对湿度100%下银依旧不变色,说明在空气质量、光照度与相对湿度中,空气质量是影响银变色的主要因素。实验结果和银化合物的化学性质的结合解释了银与各种污染离子作用最终转化为稳定硫化银的原因。实验结果为制定银质文物保护环境要求和改造方案提供了依据。     

Seismic Behavior Prediction of Flanged Unreinforced Masonry (FURM) Walls

In most available studies, unreinforced masonry (URM) walls are idealized as rectangular sections, while in reality walls have effective sectional shapes such as C, I, T, and L. In this article, the results of experimental and analytical assessment of flange effects on the behavior of I- and C-shaped URM walls are reported. Four clay brick walls at half scale were tested. Two specimens were designed with I- and C-shaped sections, and for comparison, two additional specimens were designed without flanges. The tests showed that under constant axial load the strength of the I-shaped wall increases, but that of the C-shaped wall decreases, because of out-of-plane distortion effects. Despite the loss of strength, both flanged walls indicated almost similar initial stiffness, deformation capacity, and mode of failure in comparison with walls without flanges. A mixed-mode analytical model is proposed to predict the lateral force displacement curve of flanged URM (FURM) walls. The proposed analytical model is based on section analysis of the walls and shows good agreement with previous experimental results.     

Hydrothermal monitoring in a quiescent volcanic arc: Cascade Range,northwestern United States

Ongoing (1996–present) volcanic unrest near South Sister, Oregon, is accompanied by a striking set of hydrothermal anomalies, including elevated temperatures, elevated major ion concentrations, and ³He/⁴He ratios as large as 8.6 R_A in slightly thermal springs. These observations prompted the US Geological Survey to begin a systematic hydrothermal‐monitoring effort encompassing 25 sites and 10 of the highest‐risk volcanoes in the Cascade volcanic arc, from Mount Baker near the Canadian border to Lassen Peak in northern California. A concerted effort was made to develop hourly, multiyear records of temperature and/or hydrothermal solute flux, suitable for retrospective comparison with other continuous geophysical monitoring data. Targets included summit fumarole groups and springs/streams that show clear evidence of magmatic influence in the form of high ³He/⁴He ratios and/or anomalous fluxes of magmatic CO₂ or heat. As of 2009–2012, summit fumarole temperatures in the Cascade Range were generally near or below the local pure water boiling point; the maximum observed superheat was <2.5°C at Mount Baker. Variability in ground temperature records from the summit fumarole sites is temperature‐dependent, with the hottest sites tending to show less variability. Seasonal variability in the hydrothermal solute flux from magmatically influenced springs varied from essentially undetectable to a factor of 5–10. This range of observed behavior owes mainly to the local climate regime, with strongly snowmelt‐influenced springs and streams exhibiting more variability. As of the end of the 2012 field season, there had been 87 occurrences of local seismic energy densities approximately ≥ 0.001 J/m³ during periods of hourly record. Hydrothermal responses to these small seismic stimuli were generally undetectable or ambiguous. Evaluation of multiyear to multidecadal trends indicates that whereas the hydrothermal system at Mount St. Helens is still fast‐evolving in response to the 1980–present eruptive cycle, there is no clear evidence of ongoing long‐term trends in hydrothermal activity at other Cascade Range volcanoes that have been active or restless during the past century (Baker, South Sister, and Lassen). Experience gained during the Cascade Range hydrothermal‐monitoring experiment informs ongoing efforts to capture entire unrest cycles at more active but generally less accessible volcanoes such as those in the Aleutian arc.