力觉临场感遥操作机器人(3)：环境的动力学描述

力觉临场感遥操作机器人系统是一个典型的人-机-环交互系统.环境是遥操作机器人系统最终的环节,也是操作者感知和作用的对象,环境的动力学特性对整个遥操作机器人系统的控制性能会产生直接的影响.通过分析环境在力觉临场感遥操作机器人系统中的动力学特性,建立了环境在碰撞接触、线性平稳接触和非线性平稳接触3类情况下的动力学模型,并给出了模型的等效阻抗形式,为力觉临场感遥操作机器人系统的分析提供了基础.     

顾及步行习惯的室内导航网络及其生成算法

室内导航网络是实现室内路径规划和导航的基础。针对现有室内导航网络存在拓扑连通结构不合理、生成路径几何形态不自然等问题,本文依据人类长期以来形成的“抄近路”习性及“避碰”安全需求,提出了一种符合人行走习惯的室内导航网络及其自动生成算法。该导航网络将室内可通行空间划分为普通房间和走廊,普通房间内网络映射为房间结点与门结点的直线连接;形状复杂的走廊空间则依据空间尺度和凹凸性被细分为狭窄走廊空间和开阔走廊空间,狭窄走廊空间以中轴线作为路线,开阔走廊空间则将门结点和通道口结点连接形成完全图;最后将房门结点连接到走廊路线,形成完整室内导航网络。试验结果表明:该模型及其生成算法能够依据室内空间尺度对复杂通行空间进行合理分区,生成与空间特征一致的导航网络结构,使得规划生成的最短路径形态更符合人们的行走习惯。     

2016年新疆轮台MS 5.3地震序列尾波Qc值分析

基于Sato单次散射模型,利用轮台地震台单台记录,计算并分析2016年1月14日新疆轮台M_S5.3地震及余震序列尾波Q_c值震后变化,拟合得出Q_c值随频率的变化关系为Q_c (f) =（18.0±3.19）f^1.184±0.072。结果表明,Q_c值在序列初期起伏较大,随着强震后能量的释放,Q_c值趋于平缓;低频段的Q_c值在较大余震发生前有显著变化;不同中心频率点的Q_c值变化形态不一致。对Q_c值变化特征的研究,可为地震预报提供参考依据。     

地震与强降雨作用下堆积体滑坡变形破坏机理及防治方案分析

位于西南山地堆积体滑坡常受到地震和强降雨的双重作用,查明此类滑坡变形破坏机理是地质灾害防治和风险防控的基础。文章的研究对象是鲜水河断裂带附近的炉霍县马居滑坡。研究表明,地震作用对位于斜坡地带堆积体滑坡体结构损伤明显,不但使滑坡整体稳定性下降,还促使坡体内裂隙大量发育,利于降雨入渗,进一步恶化滑坡的水文地质条件。强降雨形成的大规模洪水和泥石流下切坡脚沟道,牵引滑坡体整体向下。长历时强降雨入渗影响坡体稳定性,且在降雨结束后较长时间持续影响坡体稳定性。因此,对此类滑坡防治的对策应考虑坡脚防护和抗滑支挡设置。在对防治方案的有效性分析后,表明防护方案在极端条件下仍然能保障安全性,达防治和风险管控的目的。     

Trends in northern midlatitude atmospheric wave power from 1950 to 2099

In a warming climate, atmospheric wave activity and associated weather patterns may change, although conflicting results have been reported on this topic. Additionally, atmospheric wave changes in a future climate have mainly focused on waves of a specified spatial scale, rather than a particular spatiotemporal scale. Here, changes in the variability of Rossby waves of multiple spatiotemporal scales are analyzed using the wavenumber-frequency power spectrum, a tool commonly applied to analyze atmospheric equatorial waves. Daily 500 hPa geopotential height data over 40°–60°N from historical (1950–2005) and future (2006–2099) simulations from 20 models in the Coupled Model Intercomparison Project Phase 5 (CMIP5) under the RCP8.5 scenario were analyzed. When compared to the historical period, the late 21st century climate projections showed a decline in spectral power for both eastward and westward propagating waves with wavenumbers greater than 8 that spanned over all frequencies in all seasons, but an increase in mean power for eastward propagating waves with wavenumbers 1–7 over all frequencies was shown in winter and spring. This increase in power was accompanied by increased variance, i.e., an increased meridional extent of 500 hPa ridges and troughs, and was the result of increases in the mean number of high amplitude events and duration of activity within this wave band. These results indicate that large-scale (~ 104 km) eastward propagating weather systems may intensify with higher amplitudes for ridges and troughs, while short-scale (102–103 km) weather systems may decrease in their intensity due to reduced variability in the late 21st century under the high emissions scenario. Potential mechanisms for these changes are discussed, including enhanced Arctic warming and midlatitude-tropical interactions.     

Improved methods for estimating equilibrium climate sensitivity from transient warming simulations

Climate Dynamics - Equilibrium climate sensitivity (ECS) refers to the total global warming caused by an instantaneous doubling of atmospheric CO2 from the pre-industrial level in a climate system....     

The influence of the inter-decadal Pacific oscillation on US precipitation during 1923–2010

Precipitation over the contiguous United States exhibits large multi-decadal oscillations since the early twentieth century, and they often lead to dry (e.g., 1946–1976 and 1999-present) and wet (e.g., 1977–1998) periods and apparent precipitation trends (e.g., from the 1950s to 1990s) over most of the western and central US. The exact cause of these inter-decadal variations is not fully understood. Using observational and reanalysis data and model simulations, this paper examines the influence of the Inter-decadal Pacific Oscillation (IPO) on US precipitation. The IPO is a leading mode of sea surface temperatures (SSTs) seen mostly in the Pacific Ocean. It is found that decadal precipitation variations over much of the West and Central US, especially the Southwest, closely follow the evolution of the IPO (r = 0.85 during 1923–2010 for the Southwest US), and the dry and wet periods are associated, respectively, with the cold and warm phases of the IPO. In particular, the apparent upward trend from the 1950s–1990s and the dry decade thereafter in precipitation over much of the West and Central US are largely caused by the IPO cycles, which switched to a warm phase around 1977 and back to a cold phase around 1999. An atmospheric model forced with observed SSTs reproduces much of this association of US precipitation with the IPO (r = 0.95 between smoothed observed and simulated Southwest US precipitation during 1950–2009 and r = 0.88 between the simulated Southwest US precipitation and the IPO). Atmospheric reanalysis and model data both show a strong high (low) pressure center and anti-cyclonic (cyclonic) anomaly circulation over the North Pacific in the lower troposphere during cold (warm) phases of the IPO, which lead to dry and cold northwesterly and northerly winds and below-normal precipitation over much of the West US during IPO cold periods. The IPO induced changes are most pronounced during the boreal cold season. The results reinforce the notion that tropical Pacific SSTs (and the accompanying SST anomalies in the North Pacific) have large impacts on US precipitation and highlight the need to understand and simulate the IPO for decadal prediction of US precipitation.     

Wind tunnel simulation experiment and investigation on the electrification of sandstorms

~~Wind tunnel simulation experiment and investigation on the electrification of sandstorms~~     

Ore-Bearing Formations of the Precambrian in South China and Their Prospects

In the Precambrian System of the Yangtze and Cathaysian plates six ore-bearing formations can be identified: the Cu-Pb-Zn-bearing formations in volcanic rocks of marine facies of the Neoarchean-Paleoproterozoic, Cu-Au-bearing formations and Pb-Zn-bearing formations in volcanic rocks of marine facies of the Mesoproterozoic, Pb-Zn-bearing formations in volcaniclastic rock and carbonate rock of the Neoproterozoic, Fe-Mn-bearing formations in the volcaniclastic rock of the Neoproterozoic, and Ni-Cr-serpentine-bearing formations in ophiolite and ultrabasic rock of the Meso- and Neoproterozoic. They were mostly formed in the marginal rift valleys of the Yangtze and Cathaysian plates, where occur stratabound and stratiform ore deposits, thermal deposits and porphyry polymetallic deposits. The six regions with ore-bearing formations have good prospects for ore deposits.