Inversion of stresses from polyphase fault/slip data with high or low diversity: An updated version of INVSFS

Fault/slip data with low diversity show limited range in orientation, and their equations, according to the Wallace-Bott hypothesis often give rise to an unstable stress solution. It is necessary in this case to introduce some auxiliary constraint(s), so as to make a stable stress solution from these equations. A new method for inverting stress from polyphase fault/slip data with low diversity but having all or a majority of newly formed faults in each subset is developed in this paper. It combines a weak criterion that favors the newly formed faults, together with the Wallace-Bott hypothesis or the strong criterion. Both criteria are solved for stresses using the Fuzzy C-lines clustering analysis technique. This permits the updating of the INVSFS code (Li et al., 2005). Two artificial sets of polyphase fault/slip data with high and low diversity are chosen to demonstrate the performance of the updated version.     

Coseismic lateral offsets of surface rupture zone produced by the 2001 Mw 7.8 Kunlun earthquake,Tibet from the IKONOS and QuickBird imagery

Analyses and interpretations of 1m‐resolution IKONOS, and 61cm‐resolution QuickBird images reveal that the distribution of strike‐slip offsets and ground deformation characteristics of the coseismic surface rupture produced by the 2001 M _w 7.8 Kunlun earthquake occurred in the western segment of the strike‐slip Kunlun fault, northern Tibet. The 2001 coseismic strike‐slip offsets measured from IKONOS images range from 2 m up to 16.7 m, generally 3–8 m, which are generally consistent with those measured immediately in the field after the earthquake. The coseismic surface ruptures along which offsets were observed are mainly composed of a numerous of en echelon shear faults and cracks which are concentrated on a rupture zone ranging from a few meters up to ～500 m in width. The offsets measured along individual shear faults or crack are typically 2–7 m, but up to >10 m in several locations. Our results show that high resolution remote sensing imagery provides a powerful tool for measuring coseismic strike‐slip offsets and detecting the ground deformation produced by a large earthquake in the remote and high mountain Tibet region.     

Application of non-normal p-norm trapezoidal fuzzy number in reliability evaluation of electrical substations

This paper presented a non-normal p-norm trapezoidal fuzzy number–based fault tree technique to obtain the reliability analysis for substations system. Due to uncertainty in the collected data, all the failure probabilities are represented by non-normal p-norm trapezoidal fuzzy number. In this paper, the fault tree incorporated with the non-normal p-norm trapezoidal fuzzy number and minimal cut sets approach are used for reliability assessment of substations. An example of 66/11 kV substation is given to demonstrate the method. Further, fuzzy risk analysis problems are described to find out the probability of failure of each components of the system using linguistic variables, which could be used for managerial decision making and future system maintenance strategy.     

Application of the boundary-integral equation method to three dimensional stress analysis

The boundary-integral equation method is based on a mathematical formulation which reduces the dimensionality of a problem by relating surface tractions to surface displacements. Discretization of the surface allows a direct and standard algebraic solution for the unknown surface data. The stresses at any point are then found by direct quadrature from the entirety of surface data. Because of the reduction of the dimension of the problem, the size of the algebraic problem is considerably smaller than for finite element models. Also, since only the surface is discretized the analyst is able to achieve considerably greater resolution of interior stresses than by finite element models.The paper reports on two direct comparisons of the boundary-integral equation and finite element methods: two dimensional crack problems and a bulky three dimensional problem representative of mine structures. Discussion of the results will include accuracy, storage requirements and computer time comparisons. The paper also discusses the utility of the boundary-integral method to model three dimensional elastic bodies with through and part-through cracks.     

Nonlinear process monitoring based on kernel global–local preserving projections

A new nonlinear dimensionality reduction method called kernel global–local preserving projections (KGLPP) is developed and applied for fault detection. KGLPP has the advantage of preserving global and local data structures simultaneously. The kernel principal component analysis (KPCA), which only preserves the global Euclidean structure of data, and the kernel locality preserving projections (KLPP), which only preserves the local neighborhood structure of data, are unified in the KGLPP framework. KPCA and KLPP can be easily derived from KGLPP by choosing some particular values of parameters. As a result, KGLPP is more powerful than KPCA and KLPP in capturing useful data characteristics. A KGLPP-based monitoring method is proposed for nonlinear processes. T² and SPE statistics are constructed in the feature space for fault detection. Case studies in a nonlinear system and in the Tennessee Eastman process demonstrate that the KGLPP-based method significantly outperforms KPCA, KLPP and GLPP-based methods, in terms of higher fault detection rates and better fault sensitivity.     

Application of stereoscopic satellite images for studying Quaternary tectonics in arid regions

We introduce a flexible method for creating stereoscopic pairs of images from any interesting sub-area of the same scene of Landsat Thematic Mapper (TM)/Enhanced Thematic Mapper (ETM) and Indian Remote Sensing (IRS)-1C Pan remote sensing data by setting the Z scale. As a test of this method, stereoscopic images were used to study Quaternary deformation along the Tian Shan Orogenic Belt, north-west China. The new stereoscopic images can then provide detailed information of Quaternary deformation structures, including spatial distribution and arrangement pattern of fold structures, fault scarps and displacement of alluvial fans, terraces and drainage systems along active faults, in three dimensions. The strike–slip partitioning has been revealed by interpretation of stereoscopic images within Chinese Tian Shan. Structural interpretations derived from stereoscopic analysis were confirmed to a high degree of accuracy during a subsequent field study. The satellite remote sensing stereoscopic technique is an effective method of analysing Quaternary tectonic deformation in remote arid to semi-arid regions such as the Tian Shan.     

The Al Hoceima (Morocco) earthquake of 24 February 2004, analysis and interpretation of data from ENVISAT ASAR and SPOT5 validated by ground-based observations

The magnitude M_w = 6.3 earthquake in Al Hoceima, Morocco of 24 February, 2004 occurred in the active plate boundary accommodating the oblique convergence between Africa and Eurasia. Three different sets of estimates of its source parameters have already been published. We try to resolve the discrepancies between them by using additional data including two remote sensing satellite systems (ENVISAT and SPOT5). Using a model with a dislocation in an elastic half-space, we constrain the source parameters. The hypothesis of two subevents on distinct faults as inferred from seismological inversions is confirmed here by adopting a cross-fault mechanism. The rupture began on a left-lateral strike-slip fault striking at N10° azimuth with 90 cm of horizontal slip and then transferred to a right-lateral strike-slip fault striking at N312° azimuth with 85 cm of horizontal slip. The first fault is at 500 m depth from the free surface and the second fault is at 3 km depth. This model is consistent with ground-based observations, including GPS, seismology, and mapped surface fissures. The pair of faults activated in 2004 appears to constitute part of a complex seismogenic structure striking NNE-SSW that separates the Rif tectonic blocks.     

Co‐seismic surface ruptures produced by the 2005 Pakistan M w7.6 earthquake in the Muzaffarabad area,revealed by QuickBird imagery data

High‐resolution QuickBird imagery data have been used to analyse and detect the co‐seismic surface ruptures produced by the 2005 Pakistan M _w7.6 earthquake in the Muzaffarabad area. The analytical results and interpretations of the QuickBird images reveal that the co‐seismic surface ruptures are mostly concentrated on the pre‐existing active faults striking northwest–southeast. Most of co‐seismic surface ruptures show a deformation feature of compressional cracks having a right‐stepping echelon geometric pattern. Individual cracks vary from metre order to 1‐km in length, generally 10 to 100 m. In the northern Muzaffarabad city, an east–west striking co‐seismic surface zone of ～1 km length occurred in the jog area between two northwest–southeast striking surface rupture zones. A strong damage zone along which all buildings completely collapsed is concentrated in a deformation zone of ～60 m wide on the uplift side of the east–west striking surface rupture zone. Large‐scale landslides caused by strong ground motion are mostly constricted on the uplift side along the co‐seismic surface rupture zones. The deformation features and spatial distribution patterns of the co‐seismic surface ruptures and the ground motion direction indicate that the co‐seismic fault that triggered the 2005 Pakistan M _w 7.6 earthquake is a thrust fault with a right‐lateral slip component.     

Fault diagnosis of rolling element bearing with intrinsic mode function of acoustic emission data using APF-KNN

This paper presents a fault diagnosis technique based on acoustic emission (AE) analysis with the Hilbert–Huang Transform (HHT) and data mining tool. HHT analyzes the AE signal using intrinsic mode functions (IMFs), which are extracted using the process of Empirical Mode Decomposition (EMD). Instead of time domain approach with Hilbert transform, FFT of IMFs from HHT process are utilized to represent the time frequency domain approach for efficient signal response from rolling element bearing. Further, extracted statistical and acoustic features are used to select proper data mining based fault classifier with or without filter. K-nearest neighbor algorithm is observed to be more efficient classifier with default setting parameters in WEKA. APF-KNN approach, which is based on asymmetric proximity function with optimize feature selection shows better classification accuracy is used. Experimental evaluation for time frequency approach is presented for five bearing conditions such as healthy bearing, bearing with outer race, inner race, ball and combined defect. The experimental results show that the proposed method can increase reliability for the faults diagnosis of ball bearing.     

A general method for calculating co-seismic gravity changes in complex fault systems

A general method for calculating the total, dilatational, and free-air gravity for fault systems with arbitrary geometry, slip motion, and number of fault segments is presented. The technique uses a Green's function approach for a fault buried within an elastic half-space with an underlying driver plate forcing the system. The method is easily adapted to investigate a wide range of geophysical applications and is provided as a suite of Fortran90 routines. The Joshua Tree-Landers-Hector Mine sequence is examined and shows remarkable correlation of epicentres with dilatational gravity highs. We also demonstrate the use of the method for large thrusting events, using the Alaska Good Friday earthquake of 1964 as an example.     

Deconvolution problems and superresolution in Hilbert-transform spectroscopy based on a.c. Josephson effect

The analysis of the numerical aspects of Hilbert transform spectroscopy based on the a.c. Josephson effect is presented. The resolving power of Hilbert transform spectroscopy is determined by such factors as the linewidth of the Josephson oscillations (intrinsic or natural resolution limit) and the limitation of the measurement interval (extrinsic or technical resolution limit) like in any spectroscopic technique based on some integral transformations. The deconvolution problem in Hilbert transform spectroscopy is posed and its solution is considered using the approach of the 1st kind integral equation for the spectrum of the incident radiation constructed from the input data of the Hilbert transform spectroscopy—the ‘hilbertogram’. The program package RECOVERY based on the maximum likelihood method is used for this purpose. This method allows to attain the maximum possible resolution enhancement in output result for a given signal-to-noise ratio in the input experimental data. The samples of numerical simulations and the spectrum of frequency-modulated BWO radiation measured by means of the Josephson junction made from high-T_c superconductor are presented. It is shown also that the integral equation approach allows to recover the sought spectrum beyond the intrinsic resolution limit and to achieve the superresolution.     

Modified embedded-atom method interatomic potential for the Mg–Zn–Ca ternary system

Mg–Zn–Ca alloys are representative Mg alloys with high formability at room temperature. Their high formability is thought to be related to slip, twinning, and recrystallization of the alloys, but the detailed mechanisms have not yet been clarified. To enable atomistic simulations for investigating those behaviors, an interatomic potential for the Mg–Zn–Ca ternary system was developed. The development was based on the second nearest-neighbor modified embedded-atom method formalism, combining previously developed Mg–Zn and Mg–Ca potentials with the newly developed Zn–Ca binary potential. The Zn–Ca and Mg–Zn–Ca potentials reproduce structural, elastic, and thermodynamic properties of compounds and solution phases of relevant alloy systems in reasonable agreement with experimental data, first-principles and CALPHAD calculations. The applicability of the developed potentials is demonstrated through calculations of the effects of Zn and Ca solutes on the generalized stacking fault energy for various slip systems, segregation energy on twin boundaries, and volumetric misfit strain.     

Improving the spatial resolution of effective elastic thickness estimation with the fan wavelet transform

We show here a simple technique to improve the spatial resolution of the fan wavelet method for effective elastic thickness (T_e) estimation that we have previously developed. The technique involves reducing the number of significant oscillations within the Gaussian window of the Morlet wavelet from approximately five to three or fewer (while making an additional correction for its no-longer-zero mean value). Testing with synthetic models and data over South America indicates that the accompanying reduction in wavenumber resolution does not seriously affect the accuracy of the T_e estimates. Comparison against the more widely-used multitaper Fourier transform approach shows that the enhanced wavelet method not only improves upon the multitaper method's spatial resolution, but also is computationally much faster and requires the arbitrary variation of only one parameter compared to three for the multitaper method. Finally, we present a modified method to compute the predicted coherence using the multitaper method that, while not improving its spatial resolution, does improve the bias of recovered T_e estimates.     

A satellite remote sensing technique for geological structure horizon mapping

A satellite remote sensing technique is demonstrated for generating near surface geological structure data. This technique enables the screening of large areas and targeting of seismic acquisition during hydrocarbon exploration. This is of particular advantage in terrains where surveying is logistically difficult. Landsat Thematic Mapper (TM) data and a high resolution digital elevation model (DEM), are used to identify the map outcropping horizons. These are used to reconstruct the near surface structure. The technique is applied in Central Yeman which is characterized by a 'layer-cake' stratigraphic section and low dipping terrain. The results are validated using two-dimensional seismic data. The near surface map images faults and structure not apparent in the raw data. Comparison with the structure map generated from two-dimensional seismic data indicates very good structural and fault correlation. The near surface map successfully highlights areas of potential closure at reservoir depths.     

Towards an ensemble based system for predicting the number of software faults

Software fault prediction using different techniques has been done by various researchers previously. It is observed that the performance of these techniques varied from dataset to dataset, which make them inconsistent for fault prediction in the unknown software project. On the other hand, use of ensemble method for software fault prediction can be very effective, as it takes the advantage of different techniques for the given dataset to come up with better prediction results compared to individual technique. Many works are available on binary class software fault prediction (faulty or non-faulty prediction) using ensemble methods, but the use of ensemble methods for the prediction of number of faults has not been explored so far. The objective of this work is to present a system using the ensemble of various learning techniques for predicting the number of faults in given software modules. We present a heterogeneous ensemble method for the prediction of number of faults and use a linear combination rule and a non-linear combination rule based approaches for the ensemble. The study is designed and conducted for different software fault datasets accumulated from the publicly available data repositories. The results indicate that the presented system predicted number of faults with higher accuracy. The results are consistent across all the datasets. We also use prediction at level l (Pred(l)), and measure of completeness to evaluate the results. Pred(l) shows the number of modules in a dataset for which average relative error value is less than or equal to a threshold value l. The results of prediction at level l analysis and measure of completeness analysis have also confirmed the effectiveness of the presented system for the prediction of number of faults. Compared to the single fault prediction technique, ensemble methods produced improved performance for the prediction of number of software faults. Main impact of this work is to allow better utilization of testing resources helping in early and quick identification of most of the faults in the software system.     

An iterative procedure for finite-element stress analysis of frictional contact problems

A simple, efficient, versatile and easily adaptable, iterative finite-element technique is described for solving frictional contact problems. The method is based on logical steps to establish the contact geometry and regions of slip and nonslip. Unlike previous techniques, the approach can be extended readily to multiple contact surfaces. The scheme is demonstrated by analyzing a mechanical joint in orthotropic wood. In this case, mixed coordinate systems are used to enhance accuracy of the stresses near the pin contact region. The numerically computed values agree with those reported elsewhere.     

Model-free actuator fault detection using a spectral estimation approach: the case of the DAMADICS benchmark problem

This paper presents the application to the DAMADICS benchmark fault detection problem of a model-free fault detection technique based on the use of a specific spectral analysis tool, namely, the Squared Coherency Functions (SCFs). The detection of a fault is achieved by on-line monitoring the estimate of the squared coherency function, which is sensitive to the occurrence of significative changes in the plant dynamics. The alarm threshold are based on the estimates of the confidence intervals of the SCF. Results on both simulation and real data of the DAMADICS benchmark (which is developed to approximate the industrial process in a sugar factory located in Lublin, Poland) are outlined.     

On the reformulation of the finite element method

The finite element method has seen widespread application in various fields of engineering sciences since its conception as an aid to structural analysis and design.Work by the author[1–5] as well as others [6–12] has resulted in the reexamination of the finite element method as it is presently applied. In essence, this work focuses on the need to incorporate consideration of the idealization geometry as a dependent variable in the formulation. A technique utilized by the author to incorporate this variable is based on considering the Lagrangian a function of generalized displacements and idealization geometry [5]. It is shown that this reformulation process yields auxiliary equation in addition to the equations normally satisfied by the finite element method.In this paper the author briefly summarizes the salient feature of the reformulation process. The correct formulation for the elastostatic, elastodynamic and buckling problem are indicated. The merits of this approach are verified numerically. In the elastostatic problem this approach is shown to yield improved values for stresses and displacements. In the eigenvalue problem improved values for buckling loads and/or natural frequencies are obtained.A practical test for convergence is shown to arise naturally. An alternative strategy developed by the author [3–5] to avoid the necessity of global optimization is summarized.     

Least Squares Sub-pixel Registration Refinement Using Area Sampler Model

Super-resolution applications require sub-pixel registrations of low resolution images to be almost exact due to the deterioration caused by inaccurate image registration. A linear-least-squares technique is proposed to refine sub-pixel translation parameters, which can be employed when the images are registered but just where there is not enough sub-pixel accuracy. In the technique, it is assumed that low resolution pixels are obtained by area sampling high resolution pixel field which have twice the density of their low resolution correspondents. Using this downsampling schema, a set of equations is formed. Assumed geometry and layout provide a constraint set to be used with the equation set. The sub-pixel translations are then found using least-squares-solution-with-equality-constraints. The method is shown to improve the registration accuracy.     

Coseismic deformation and source model of the 12 November 2017 MW 7.3 Kermanshah Earthquake (Iran–Iraq border) investigated through DInSAR measurements

A large earthquake with a magnitude of M_W 7.3 struck the border of Iran and Iraq at the province of Kermanshah, Iran. In our study, coseismic deformation and source model of the 12 November 2017 Kermanshah Earthquake are investigated using ALOS-2 ScanSAR and Sentinel-1A/B TOPSAR Differential Interferometric Synthetic Aperture Radar (DInSAR) techniques. Geodetic inversion has been performed to constrain source parameters and invert slip distribution on the fault plane. The optimised source model from joint inversion shows a blind reverse fault with a relatively large right-lateral component, striking 353.5° NNW-SSE and dipping 16.3° NE. The maximum slip is up to 3.8 m at 12–14 km depth and the inferred seismic moment is 1.01 × 10²⁰ Nm, corresponding to M_W 7.3, consistent with seismological solutions. The high-resolution optical images from SuperView-1 satellite suggest that most of the linear surface features mapped by DInSAR measurements are landslides or surface cracks triggered by the earthquake. Coulomb stress changes on the source fault indicating consistency between aftershock distribution and high loaded stress zones. Based on the stress change on neighbouring active faults around this area, the Kermanshah Earthquake has brought two segments of the Zagros Mountain Front Fault (MFF), MFF-1 and MFF-2, 0.5–3.1 MPa and 0.5–1.96 MPa closer to failure, respectively, suggesting the risk of future earthquakes. Recent major aftershocks (M_W≥ 5.0) could probably ease the seismic hazard on MFF-2, but the risk of earthquakes on MFF-2 is still increasing.