基于 BP神经网络和回归分析的隧洞塌方高度预测模型

隧洞塌方的发生与多种因素有关,本文以小关子水电站引水隧洞为例来讨论如何用相关的因素建立隧洞塌方高度的预测模型。经过分析后认为该隧洞塌方高度主要与断层在洞向上的视倾角和厚度,水电围岩分类评分和围岩的RQD值有关。先以此四个因素为自变量,塌方高度为因变量建立起隧洞塌方高度的多元回归模型,利用回归模型的结果对BP神经网络预测模型所需的样本进行扩充,进而建立起BP神经网络塌方高度预测模型。     

基于分数阶模型的磁流变阻尼器振动系统的预测控制

磁流变阻尼器因其可控阻尼的特性可以用于制作优质减振器,近年来,它与各种控制策略的结合设计已在工业振动控制领域得到了广泛的应用.研究表明,分数阶模型对磁流变阻尼器的拟合精度更高.本文使用分数阶模型描述磁流变阻尼器的粘弹特性,并利用Oustaloup近似方法得到易处理的分数阶传递函数近似值,离散化处理后选取输出跟踪输入的二次型性能指标设计了一种新的模型预测控制器.最后,通过仿真实验证明了该分数阶模型预测控制器具有良好的动态性能,验证了方案的可行性与稳定性.     

Characterizing and Predicting Traffic Accidents in Extreme Weather Environments

Motorists are vulnerable to extreme weather events, which are likely to be exacerbated by climate change throughout the world. Traffic accidents are conceptualized in this article as the result of a systemic failure that includes human, vehicular, and environmental factors. The snowstorm and concurrent accidents that occurred in the Northeastern United States on 26 January 2011 are used as a case study. Traffic accident data for Fairfax County, Virginia, are supplemented with Doppler radar and additional weather data to characterize the spatiotemporal patterns of the accidents resulting from this major snowstorm event. A kernel density smoothing method is implemented to identify and predict patterns of accident locations within this urban area over time. The predictive capability of this model increases over time with increasing accidents. Models such as these can be used by emergency responders to identify, plan for, and mitigate areas that are more susceptible to increased risk resulting from extreme weather events.     

Study on eliminating noises in short-period data of geomagnetic intensity by using numerical multichannel predictive filtering

ＩｎｔｒｏｄｕｃｔｉｏｎＩｔｉｓｋｎｏｗｎｔｈａｔｔｈｅｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｉｍｐｅｄａｎｃｅｓｏｆｔｈｅｃｒｕｓｔｍｅｄｉｕｍｍａｙｂｅｃｈａｎｇｅｄｄｕｒｉｎｇｔｈｅｐｒｅｇｎａｎｃｙｏｆａｎｅａｒｔｈｑｕａｋｅ,ａｎｄｍａｙｌｅａｄｔ...     

Comment on “A note on salt intrusion in funnel-shaped estuaries: Application to the Incomati estuary, Mozambique” by

A comment is provided on the paper by Brockway et al. (2006. A note on salt intrusion in funnel-shaped estuaries: application to the Incomati estuary, Mozambique. Estuarine, Coastal and Shelf Science 66, 1–5) on a simple method to determine the salt intrusion in the Incomati estuary. Although this method is able to describe the salt intrusion in the Incomati reasonably well with only limited information, it is demonstrated that with the same data, but a more up-to-date methodology, a better and generally applicable equation could have been obtained.     

基于欧拉迭代模型预测的欠驱动水面船舶路径跟踪控制

【目的】解决具有外部受风流干扰和舵角输入受约束的欠驱动船舶路径跟踪问题。【方法】采用基于欧拉迭代的模型预测控制算法(MPC)对欠驱动船舶路径跟踪进行控制。【结果】MPC能够灵活地处理舵角输入受约束问题,欧拉迭代法离散和预测船舶未来状态可以简化MPC设计的运算。为弥补欧拉迭代法在精度上的不足,直接以分离型船舶模型(MMG)作为MPC的预测模型。应用径向基函数(RBF)神经网络历史信息训练实现对外界风流干扰的逼近及补偿。【结论】所设计的控制器可以使船舶在考虑风流干扰和舵角约束的情况下准确地跟踪上设定的路径,所提控制算法的有效性得到验证。     

吉林二道甸金矿成矿控制条件分析及靶区评价

二道甸子金矿具有独特的成因机制及成矿控制条件。通过对该矿主矿带金矿化作用与古生代含碳变质岩系、弧形构造带以及与海西期黑云母花岗岩侵入作用之间的关系分析，指出后者是金矿成矿的主要控制条件；并据此总结出金矿富集规律和矿体预测准则，指出在矿区外国及深部存在进一步工作的找矿靶区。     

Predictive control of seismic structures with semi‐active friction dampers

In this paper a predictive control method especially suitable for the control of semi‐active friction dampers is proposed. By keeping the adjustable slip force of a semi‐active friction damper slightly lower than the critical friction force, the method allows the damper to remain in its slip state throughout an earthquake of arbitrary intensity, so the energy dissipation capacity of the damper can be improved. The proposed method is formulated in a discrete‐time domain and cast in the form of direct output feedback for easy control implementation. The control algorithm is able to produce a continuous and smooth slip force for a friction damper and thus avoid exerting the high‐frequency structural response that usually exists in structures with conventional friction dampers. Using a numerical study, the control performance of a multiple degrees of freedom (DOF) structural system equipped with passive friction dampers and semi‐active dampers controlled by the proposed method are compared. The numerical case shows that by merely using a single semi‐active friction damper and a few sensors, the proposed method is able to achieve better acceleration reduction than the case using multiple passive dampers. Copyright © 2004 John Wiley & Sons, Ltd.     

Development of rational models for tunnel blast prediction based on a parametric study

The empirical models available for prediction of the tunnel blast results like pull ratio, specific charge, specific drilling and overbreak have some inherent shortcoming in absence of any parametric study at the backdrop. Hence, the models use different constituting parameters and provide values which differ widely. After a thorough review of literature and field investigations in the drivages of mines and tunnels some parameters were identified. Those parameters were subjected to Multiple Linear Regression analyses to filter out the most influencing ones which represent the rockmass properties, the tunnel configurations and the blast designs. A parameter called Tunnel Blasting Index (TBI) was conceptualized and was expressed in terms of those most influencing parameters. All the blast results observed during the filed investigations could be well related to a single index TBI. Some adjustments on account of shape of the tunnel and joint orientations, which were not addressed in the available models, are suggested in the developed models.