Probability Distributions.- Linear Models for Regression.- Linear Models for Classification.- Neural Networks.- Kernel Methods.- Sparse Kernel Machines.- Graphical Models.- Mixture Models and EM.- Approximate Inference.- Sampling Methods.- Continuous Latent Variables.- Sequential Data.- Combining Models.

Pattern Recognition and Machine Learning

The validity of the cubic law for laminar flow of fluids through open fractures consisting of parallel planar plates has been established by others over a wide range of conditions with apertures ranging down to a minimum of 0.2 µm. The law may be given in simplified form by Q/Δh = C(2b)3, where Q is the flow rate, Δh is the difference in hydraulic head, C is a constant that depends on the flow geometry and fluid properties, and 2b is the fracture aperture. The validity of this law for flow in a closed fracture where the surfaces are in contact and the aperture is being decreased under stress has been investigated at room temperature by using homogeneous samples of granite, basalt, and marble. Tension fractures were artificially induced, and the laboratory setup used radial as well as straight flow geometries. Apertures ranged from 250 down to 4µm, which was the minimum size that could be attained under a normal stress of 20 MPa. The cubic law was found to be valid whether the fracture surfaces were held open or were being closed under stress, and the results are not dependent on rock type. Permeability was uniquely defined by fracture aperture and was independent of the stress history used in these investigations. The effects of deviations from the ideal parallel plate concept only cause an apparent reduction in flow and may be incorporated into the cubic law by replacing C by C/ƒ. The factor ƒ varied from 1.04 to 1.65 in these investigations. The model of a fracture that is being closed under normal stress is visualized as being controlled by the strength of the asperities that are in contact. These contact areas are able to withstand significant stresses while maintaining space for fluids to continue to flow as the fracture aperture decreases. The controlling factor is the magnitude of the aperture, and since flow depends on (2b)3, a slight change in aperture evidently can easily dominate any other change in the geometry of the flow field. Thus one does not see any noticeable shift in the correlations of our experimental results in passing from a condition where the fracture surfaces were held open to one where the surfaces were being closed under stress.

/pdf/validity-of-cubic-law-for-fluid-flow-in-a-deformable-rock-2ynq4id3hq.pdf

VALIDITY OF CUBIC LAW FOR FLUID FLOW IN A DEFORMABLE ROCK FRACTURE - eScholarship

https://bura.brunel.ac.uk/bitstream/2438/13152/4/Fulltext.pdf

Critical analysis of Big Data challenges and analytical methods

http://ieeexplore.ieee.org/iel5/5/31047/01444179.pdf

Fundamentals of acoustics

http://www.ukm.my/kamal3/psm/pfpstochastics.pdf

The stochastic finite element method: Past, present and future

A phase-field-based multi-physics coupling numerical method and its application in soil–water inrush accident of shield tunnel

Large diameter shield tunnel becomes increasingly popular for under water and undersea channels built in cities. The probability of going through multi-layered ground formation within the tunnel depth is increasing as the diameter of shield tunnel increases. So it is necessary to consider the influence of ground variation on deformation and internal forces of shield tunnel within the range of tunnel depth. In this paper, two dimensional elastic modulus random field model which is lognormal distributed is employed to characterize the ground variation. Five parameters including tunnel diameter, tunnel buried depth, mean value and COV of ground elastic modulus, and vertical SOF of elastic modulus random field are changed in orthogonal test to study how these parameters influence tunnel internal forces and deformation. Monte Carlo simulation is performed and distributions of tunnel deformation and internal forces are all normally distributed. Mean value of tunnel deformation and internal forces are almost negative linear with mean value of ground elastic modulus, but not sensitive to COV of ground elastic modulus. Tunnel crown bending moment has the largest variability while invert axial force has the smallest variability among all structural response indicators.

Numerical Analysis of Influence of Ground Variation on Deformation and Internal Forces of Large Diameter Shield Tunnel

An early detection of structural damages is critical for the decision making of repair and replacement maintenance in
order to guarantee a specified structural reliability. Consequently, the structural damage detection, based on vibration
data measured from the structural health monitoring (SHM) system, has received considerable attention recently. The
traditional time-domain analysis techniques, such as the least square estimation (LSE) method and the extended Kalman
filter (EKF) approach, require that all the external excitations (inputs) be available, which may not be the case for some
SHM systems. Recently, these two approaches have been extended to cover the general case where some of the external
excitations (inputs) are not measured, referred to as the LSE with unknown inputs (LSE-UI) and the EKF with unknown
inputs (EKF-UI). Also, new analysis methods, referred to as the sequential non-linear least-square estimation with
unknown inputs and unknown outputs (SNLSE-UI-UO) and the quadratic sum-square error with unknown inputs
(QSSE-UI), have been proposed for the damage tracking of structures when some of the acceleration responses are not
measured and the external excitations are not available. In this paper, these newly proposed analysis methods will be
compared in terms of accuracy, convergence and efficiency, for damage identification of structures based on
experimental data obtained through a series of experimental tests using a small-scale 3-story building model with white
noise excitation. The capability of the LSE-UI, EKF-UI, SNLSE-UI-UO and QSSE-UI approaches in tracking the
structural damages will be demonstrated.

Comparison of various structural damage tracking techniques with unknown excitations based on experimental data

Nowadays, a great number of long span cable-stayed and suspension bridges are being constructed in China. As the length of the main span increases, vibrations of these long span bridges are becoming more serious and sometimes unacceptable during the construction period. In this connection, control devices should be installed to mitigate the vibration of the pylon and the cantilever girders. Compared with the passive damper system, the AMD system has significant advantages in terms of the control of various modes of the structures, especially for close modes of the bridge at cantilever construction stage. To control the multiple modes of the structure by using multiple AMD system, the design and placements of AMD is critical. The following two issues are studied for the vibration control of the bridge at cantilever stage under seismic excitations: (a) the design and the parameter optimization of the AMD system; and (b) the optimal placements of the AMD system. Simulation procedure is carried out to evaluate the effectiveness of the designed AMD systems for the vibration control, based on the model of the 3 rd Nanjing Yangtze River Bridge. The adaptabilities of the multiple AMD system are presented and the possibilities of applying multiple AMD systems to the long span bridges under construction are investigated.

Active Control of Cable-Stayed Bridge with Close Modes during Construction

Global assessment of structural conditions is important for structural health monitoring system. In particular, online or almost online structural parametric identification, based on vibration data measured from sensors, has received considerable attention recently. However, the problem becomes more challenging when the structure is complex and the number of degree-of-freedom (DOF) is large. A newly proposed time domain analysis methodology, referred to as the sequential nonlinear LSE (SNLSE) approach, has been studied and shown to be useful for the online tracking of parameters for structures with small DOFs. In this paper, the SNLSE approach will be applied for global assessment of an experimental cable-stay bridge model with large DOFs. A dynamic equivalent model of the bridge will be established and finite element analysis will be carried out to formulate the equation of motion. Numerical analysis will be conducted with different simulated damage scenarios and limited number of response data is considered. The capability of the proposed SNLSE approach in identifying the structural parameters and assessing the structural conditions will be verified.

Hongwei Huang

Papers

A phase-field-based multi-physics coupling numerical method and its application in soil–water inrush accident of shield tunnel

Numerical Analysis of Influence of Ground Variation on Deformation and Internal Forces of Large Diameter Shield Tunnel

Comparison of various structural damage tracking techniques with unknown excitations based on experimental data

Active Control of Cable-Stayed Bridge with Close Modes during Construction

Global assessment of a cable-stayed bridge model using snlse approach