In this paper,a novel remaining useful life prediction approach considering fault effects is proposed.The Wiener process is used to construct the degradation process of single performance characteristic with the fault...In this paper,a novel remaining useful life prediction approach considering fault effects is proposed.The Wiener process is used to construct the degradation process of single performance characteristic with the fault effects.The first passage time based remaining useful life distribution is calculated by assuming fault occurrence moment is a random variable and follows a certain distribution.Expectation maximization algorithm is employed to estimate model parameters,where the fault occurrence moment is considered as a missing data.Finally,a Copula function is used to describe the dependence between the multiple performance characteristics and derive joint remaining useful life(RUL)distribution of product with the fault effects.The effectiveness of the proposed approach is verified by the experiments of turbofan engines.展开更多
Infill walls that are considered for the design phase of RC buildings completely change damage mechanisms.In such cases,field studies conducted after destructive earthquakes show that the damage is advanced,especially...Infill walls that are considered for the design phase of RC buildings completely change damage mechanisms.In such cases,field studies conducted after destructive earthquakes show that the damage is advanced,especially in structures without infilling walls on the ground floors.The same situation was observed in destructive earthquakes such as the 2023 Kahramanmaras earthquake.The main goal of this study is to examine the effect of the infill wall situation on the behavior of structures in earthquakes and to examine how the near-fault effect will change the damage levels of structures with and without infill walls.In this context,the effect of the infill wall situation was examined by utilizing the Kahramanmaras earthquake data.As a result of the study,it was observed that designs with infill wall building models gave better results compared to the other models.The near fault effect was observed to be more dominant in building models without infill walls and with open stories.In conclusion,the infill walls was positively affected with regard to the near fault effect and the features of the building,such as period values,ground story behavior,story shear forces,column moment values,inter-story drift ratio,and base shear forces on ground floors,and increased base shear force.展开更多
Generalized stacking-fault energies （GSFEs） of basal-plane stacking faults 11 and 12 in Mg alloys have been studied based on first-principles calculations, where 43 alloying elements were considered. It is found tha...Generalized stacking-fault energies （GSFEs） of basal-plane stacking faults 11 and 12 in Mg alloys have been studied based on first-principles calculations, where 43 alloying elements were considered. It is found that the most contributing features of alloying elements to GSFEs are bulk modulus, equilibrium volume, binding energy, atomic radius and ionization energy. Both bulk modulus and ionization energy exhibit positive relationships with GSFEs, and the others show opposite relationships. Multiple regressions have been performed to offer a quantitative prediction for basal-plane GSFEs in Mg-X systems. GSFEs, alloying effects of elements and the prediction model established within this work may provide guidelines for new Mg alloys design with better ductility.展开更多
In the 1990s, several major earthquakes occurred throughout the world, with a common observation that near fault ground motion （NFGM） characteristics had a distinct impact on causing damage to civil engineering stru...In the 1990s, several major earthquakes occurred throughout the world, with a common observation that near fault ground motion （NFGM） characteristics had a distinct impact on causing damage to civil engineering structures that could not be predicted by using far field ground motions. Since then, seismic responses of structures under NFGMs have been extensively examined, with most of the studies focusing on structures with relatively short fundamental periods, where the traveling wave effect does not need to be considered. However, for long span bridges, especially arch bridges, the traveling wave （only time delay considered） effect may be very distinct and is therefore important. In this paper, the results from a case study on the seismic response of a steel arch bridge under selected NFGMs is presented by considering the traveling wave effect with variable apparent velocities. The effects of fling step and long period pulses of NFGMs on the seismic responses of the arch bridge are also discussed.展开更多
Many destructive earthquakes happened in Tehran, Iran in the last centuries. The existence of active faults like the North Tehran is the main cause of seismicity in this city. According to past investigations, it is e...Many destructive earthquakes happened in Tehran, Iran in the last centuries. The existence of active faults like the North Tehran is the main cause of seismicity in this city. According to past investigations, it is estimated that in the scenario of activation of the North Tehran fault, many structures in Tehran will collapse. Therefore, it is necessary to incorporate the near field rupture directivity effects of this fault into the seismic hazard assessment of important sites in Tehran. In this study, using calculations coded in MATLAB, Probabilistic Seismic Hazard Analysis （PSHA） is conducted for an important site in Tehran. Following that, deaggregation technique is performed on PSHA and the contribution of seis- mic scenarios to hazard is obtained in the range of distance and magnitude. After identifying the North Tehran fault as the most hazardous source affecting the site in 10000-year return period, rupture directivity effects of this fault is incorporated into the seismic hazard assessment using Somerville et al. （1997） model with broadband approach and Shahi and Baker （2011） model with narrowband approach. The results show that the narrowband approach caused a 27% increase in the peak of response spectrum in 10000-year return period compared with the conventional PSHA. Therefore, it is necessary to incorporate the near fault rupture directivity effects into the higher levels of seismic hazard assessment attributed to important sites.展开更多
Intrinsic stacking-fault energy is a critical parameter influencing the various mechanical performances of aus- tenitic steels with high Mn concentrations. However, quantitative calculations of the stacking-fault ener...Intrinsic stacking-fault energy is a critical parameter influencing the various mechanical performances of aus- tenitic steels with high Mn concentrations. However, quantitative calculations of the stacking-fault energy （SFE） of the face-centered cubic （fcc） Fe, including the changes in concentrations and geometrical distribution of alloying atoms, cannot be obtained by using previous computation models. On the basis of the interaction energy model, we evaluated the effects of a single alloying atom （i.e., Mn, A1, Si, C and N）, as well as its aggregates, including the Mn-X dimer and Mn2-X trimer （X = A1, Si, C and N） on the SFE of the fcc Fe via first-principle calculations. Given low concentrations （〈10 wt%） of alloying atoms, dimers and trimers, theoretical calculations reveal the following： （1） Alloying atom Mn causes a decrease in the SFE, whereas A1, Si, C and N significantly increase the SFE; （2） combination with other alloying atoms to form the Mn-X dimer （X = A1, Si, C and N） exerts an effect on SFE that, to a certain extent, is close to that of the corresponding single X atom; （3） the interaction between Mnz-X and the stacking fault is stronger than that of the corresponding single X atom, inducing a significant increase in the SFE of fcc Fe. The theoretical results we obtained demonstrate that the increase in SFE in high-Mn steel originates from the synergistic effect of Mn and other trace alloy atoms.展开更多
There are four types of metamorphic rocks in the Marinwobo fault, i.e, cataclasite, mylonite, mictosite and migmatitic granite, and the formation of these rocks is due to the progressive metamorphism of the pyroclasti...There are four types of metamorphic rocks in the Marinwobo fault, i.e, cataclasite, mylonite, mictosite and migmatitic granite, and the formation of these rocks is due to the progressive metamorphism of the pyroclastics. The fluids play a very important role in the metamorphic process of these rocks in the Marinwobo fault, the most important feature is that the fluids not only result in the migration of the major elements of the deformation rocks, but also result in the volume loss of the deformation rocks in the deformation process. Thus the migration laws of the major elements in different stages of the progressive metamorphic process are discussed according to mass balance equations. Finally, the quantitative analysis of the mass loss and volume loss of the different rocks the in Marinwobo fault is discussed in this paper.展开更多
Root-mean-square distance Drms with characteristic of weighted-average is introduced in this article firstly. Drms can be used to capture the general proximity of a site to a dipping fault plane comparing with the rup...Root-mean-square distance Drms with characteristic of weighted-average is introduced in this article firstly. Drms can be used to capture the general proximity of a site to a dipping fault plane comparing with the rupture distance Drup and the seismogenic distance Dseis. Then, using Drup, Dseis and Drms, the hanging wall/footwall effects on the peak ground acceleration (PGA) during the 1999 Chi-Chi earthquake are evaluated by regression analysis. The logarithm residual shows that the PGA on hanging wall is much greater than that on footwall at the same Drup or Dseis when the Drup or Dseis is used as site-to-source distance measure. In contrast, there is no significant difference between the PGA on hanging wall and that on footwall at the same Drms when Drms is used. This result confirms that the hanging wall/footwall effect is mainly a geometric effect caused by the asymmetry of dipping fault. Therefore, the hanging wall/footwall effect on the near-fault ground motions can be ignored in the future attenuation analysis if the root-mean-square distance Drms is used as the site-to-source distance measure.展开更多
In this paper, the reservoir temperatures of 14 hot spring samples collected from the northern segment of theRed River Fault are calculated by using the mixing-model of SiO2-geothermometer. Based on the features ofres...In this paper, the reservoir temperatures of 14 hot spring samples collected from the northern segment of theRed River Fault are calculated by using the mixing-model of SiO2-geothermometer. Based on the features ofreservoir temperatures and densities of hot springs, the northern segment of the Red River Fault is furtherdivided into 4 sub-segments. The influence of weakening effect of water on seismic activities is discussed fromthe view point of fault-weakening effect of water. It is suggested that the difference in seismic activity between various sub-segments is principally caused by the difference in intensity of the fault-weakening effect ofwater of these sub-segments. The Eryuan sub-segment where the reservoir temperatures are high and the hotsprings are dense corresponds to a slipped region, however, the Jianchuan and Midu sub-segments where thereservoir temperatures are lower and the hot springs are fewer as well as the Dan sub-segment where the hotspring are very few all correspond to locked regions. It is suggested that Dan sub-segment is the riskiest region for strong earthquake preparation, while the possibility for strong earthquake preparation is very little inthe Eryuan sub-segment.展开更多
Based on the stress field distribution rule of the mining floor under abutment pressure, we have established a simplified mechanical model, which contains multiple factors relating to activation and evolution of insid...Based on the stress field distribution rule of the mining floor under abutment pressure, we have established a simplified mechanical model, which contains multiple factors relating to activation and evolution of insidious water-conductive faults. The influence of normal and shear stresses on fault activation and effective shear stress distribution in the fault plane was acquired under mining conditions.Using fracture mechanics theory to calculate the stress intensity factor of an insidious fault front, we have derived the criterion for main fault activation. Results indicate that during the whole working face advance, transpressions are exerted on fault planes twice successively in opposite directions. In most cases, the second transpression is more likely to lead to fault activation. Activation is influenced by many factors, predominant among which are: burial depth of the insidious fault, friction angle of the fault plane, face advance direction and pore water pressure. Steep fault planes are more easily activated to induce a sustained water inrush in the face.展开更多
Ground motions with forward-directivity effect in the near-fault region are obviously different from ordinary far-field ground motions. Design spectral models for this kind of motions have been proposed by correlating...Ground motions with forward-directivity effect in the near-fault region are obviously different from ordinary far-field ground motions. Design spectral models for this kind of motions have been proposed by correlating simple pulses with parameters attenuation relationships in a previous study of the authors. To further test the applica- bility of the established design spectral model, we analyze ground motion pseudo-velocity response spectra （PVS）, normalized pseudo-velocity spectra （NPVS） and bi-normalized pseudo-velocity spectra （BNPVS） of 53 typical near-fault forward-directivity ground motions. It is found that BNPVS not only has more salient features to reflect the difference between soil and rock sites, but also has less scattering to reveal the nature of forward-directivity motions. And then, BNPVS is used for prediction of design spectra accounting for the influence of site conditions, and the constructed design spectra are compared with those spectra established previously. It is concluded that site condition can heavily affect ground motions, buildings on rock can be even more dangerous than those on soil sites, in particular for ordinary buildings with short to middle vibration periods. Finally, pulse models are also suggested for structural analyses in the near-fault region.展开更多
It was shown from the study on the recently near-fault earthquake ground motions that the near-fault effects were seldom considered in the existing Chinese seismic code. Referring to the UBC97 design concept for near-...It was shown from the study on the recently near-fault earthquake ground motions that the near-fault effects were seldom considered in the existing Chinese seismic code. Referring to the UBC97 design concept for near-fault factors, based on the collected world-widely free-site records of near-fault earthquakes ground motions classified by earthquake magnitude and site condition, the attenuation relationship expressions of the acceleration spectrum demand at the key points within the long period and moderate period were established in term of the earthquake magnitude and the site condition. Furthermore, the near-fault factors＇ expressions about the earthquake magnitude and the fault distance were deduced for the area lack of near-fault strong earthquake records. Based on the current Chinese Building Seismic Design Code, the near-fault effect factors and the modified design spectral curves, which were valuable for the seismic design, were proposed to analyze the seismic response of structures.展开更多
Since the joint actuator of the space robot executes the control instructions frequently in the harsh space environment,it is prone to the partial loss of control effectiveness(PLCE)fault.An adaptive fault-tolerant co...Since the joint actuator of the space robot executes the control instructions frequently in the harsh space environment,it is prone to the partial loss of control effectiveness(PLCE)fault.An adaptive fault-tolerant control algorithm is designed for a space robot system with the uncertain parameters and the PLCE actuator faults.The mathematical model of the system is established based on the Lagrange method,and the PLCE actuator fault is described as an effectiveness factor.The lower bound of the effectiveness factors and the upper bound of the uncertain parameters are estimated by an adaptive strategy,and the estimated value is fed back to the control algorithm.Compared with the traditional fault-tolerant algorithms,the proposed algorithm does not need to predetermine the lower bound of the effectiveness factor,hence it is more in line with the actual engineering application.It is proved that the algorithm can guarantee the stability of the closed-loop system based on the Lyapunov function method.The numerical simulation results show that the proposed algorithm can not only compensate for the uncertain parameters,but also can tolerate the PLCE actuator faults effectively,which verifies the effectiveness and superiority of the control scheme.展开更多
Since the early 1970s tremendous growth has been seen in the research of software reliability growth modeling. In general, software reliability growth models （SRGMs） are applicable to the late stages of testing in s...Since the early 1970s tremendous growth has been seen in the research of software reliability growth modeling. In general, software reliability growth models （SRGMs） are applicable to the late stages of testing in software development and they can provide useful information about how to improve the reliability of software products. A number of SRGMs have been proposed in the literature to represent time-dependent fault identification / removal phenomenon; still new models are being proposed that could fit a greater number of reliability growth curves. Often, it is assumed that detected faults are immediately corrected when mathematical models are developed. This assumption may not be realistic in practice because the time to remove a detected fault depends on the complexity of the fault, the skill and experience of the personnel, the size of the debugging team, the technique, and so on. Thus, the detected fault need not be immediately removed, and it may lag the fault detection process by a delay effect factor. In this paper, we first review how different software reliability growth models have been developed, where fault detection process is dependent not only on the number of residual fault content but also on the testing time, and see how these models can be reinterpreted as the delayed fault detection model by using a delay effect factor. Based on the power function of the testing time concept, we propose four new SRGMs that assume the presence of two types of faults in the software： leading and dependent faults. Leading faults are those that can be removed upon a failure being observed. However, dependent faults are masked by leading faults and can only be removed after the corresponding leading fault has been removed with a debugging time lag. These models have been tested on real software error data to show its goodness of fit, predictive validity and applicability.展开更多
The plane-wave assumption for incident SH waves can be a good approximation for cylindrical and spherical waves radiated from finite sources, even when the source is as close as twice the size of the inhomogeneity, an...The plane-wave assumption for incident SH waves can be a good approximation for cylindrical and spherical waves radiated from finite sources, even when the source is as close as twice the size of the inhomogeneity, and when the source and the inhomogeneity are described within the same coordinate system. However, in a more general setting, and when the fault＇s radiation pattern must be considered, the plane-wave approximation may not yield satisfactory answers for arbitrary orientation of the fault. Jalali et al. （2015） demonstrated this for a semi-cylindrical, sedimentary valley, and in this study we extend their results to a case in which the semi-circular, sedimentary valley is replaced by a canyon. We describe the effects of incident cylindrical waves on the amplitudes of surface motion in and near the semi-cylindrical canyon when the causative faults are at different distances and have different curvatures and orientations.展开更多
The alluvial fan of the Shahdad in Derakt-Tangan River is one of the biggest alleviation in total dry area in the north eastern Kerman. This alluvial fan is formed effected by different materials erosion in drainage b...The alluvial fan of the Shahdad in Derakt-Tangan River is one of the biggest alleviation in total dry area in the north eastern Kerman. This alluvial fan is formed effected by different materials erosion in drainage basin of Derakt-Tangan River and laying these materials in the final part of this drainage basin called Lut. Tectonics activate with efficacy in the place of the settlement of the alluvial fan. The region, which is being studied, is one of the active tectonic regions. The severe tectonic activities in the studying region have been proved by several observations. One of the most important evidences in the region is the various faults in the area and implies to fan alluvium （from head to end）, study line profile in past and present. The most important fault of the region is the great fault of ＂Nay band＂, the southern fault of Shahdad and the series of faults having the direction of north-western to south-eastern and northern and southern. The drainage basin of alluvial fan of the Derakt-Tangan River leads from east to Kavir-lut, from west to the Baghe-Bala Mountains and Kalisaky from The aim of this article is the morphology of Derakt-Tangan north to the altitutes of Dahran and from south to the mountains of Jeffan river fan indicative on neotectonics in the region.展开更多
Understanding hydrocarbon migration and accumulation mechanisms is one of the key scientif ic problems that should be solved for effective hydrocarbon exploration in the superimposed basins developed in northwest Chin...Understanding hydrocarbon migration and accumulation mechanisms is one of the key scientif ic problems that should be solved for effective hydrocarbon exploration in the superimposed basins developed in northwest China. The northwest striking No.1 slope break zone, which is a representative of superimposed basins in the Tarim Basin, can be divided into five parts due to the intersection of the northeast strike-slip faults. Controlled by the tectonic framework, the types and properties of reservoirs and the hydrocarbon compositions can also be divided into five parts from east to west. Anomalies of all the parameters were found on the fault intersection zone and weakened up-dip along the structural ridge away from it. Thus, it can be inferred that the intersection zone is the hydrocarbon charging position. This new conclusion differs greatly from the traditional viewpoint, which believes that the hydrocarbon migrates and accumulates along the whole plane of the No.1 slope break zone. The viewpoint is further supported by the evidence from the theory of main pathway systems, obvious improvement of the reservoir quality （2-3 orders of magnitude at the intersection zone） and the formation mechanisms of the fault intersection zone. Differential hydrocarbon migration and entrapment exists in and around the strike- slip faults. This is controlled by the internal structure of faults. It is concluded that the more complicated the fault structure is, the more significant the effects will be. If there is a deformation band, it will hinder the cross fault migration due to the common feature of two to four orders of magnitude reduction in permeability. Otherwise, hydrocarbons tend to accumulate in the up-dip structure under the control of buoyancy. Further research on the internal fault structure should be emphasized.展开更多
A numerical model for generating normal fault earthquakes in the Qinghai-Xizang Plateau′S upper crust is constructed with 3-D elasto-viscous finite element method. Based on the numerical simulation calculation,some c...A numerical model for generating normal fault earthquakes in the Qinghai-Xizang Plateau′S upper crust is constructed with 3-D elasto-viscous finite element method. Based on the numerical simulation calculation,some conclusions were got:If the effective viscosity of the upper crust material is less than that of lower strata of the crust in the Qinghai-Xizang Plateau, even under the strong push of India continent,the stress state of the upper crust can still be extensional in south part of the Qinghai-Xizang Plateau.Numerical simulations show that the stress state changes with the depth of the lithosphere,from extensional stress state in upper crust to compressive in the lower part.Extensional stress state may exist mainly in the upper crust of the south part of the Qinghai-Xizang Plateau.展开更多
Based on the performance of submarine cables in past earthquakes, an analytical method to determine cable performance under seabed fault movement is proposed in this paper. First, common types of earthquake damage to ...Based on the performance of submarine cables in past earthquakes, an analytical method to determine cable performance under seabed fault movement is proposed in this paper. First, common types of earthquake damage to submarine cables are summarized, which include seabed displacement induced by fault movement, submarine landslides and seabed soil liquefaction, etc. The damage is similar to damage observed to buried pipelines following land earthquakes. The Hengchun earthquake of Dec. 26, 2006 is used as a case study. The M7.2 earthquake occurred in the South China Sea at 20：26 Beijing Time, and caused 14 international submarine cables to sever and break. The results show that the proposed method predicts damage similar to that observed in the Hengchun earthquake. Based on parametric studies of the influence of the water depth and the magnitude of the submarine earthquake, countermeasures to prevent damage to submarine cables are proposed.展开更多
The permanent displacement of seismic slopes can be regarded as an effective criterion for stability estimation. This paper studied the characteristics of permanent displacements induced by velocity pulse-like ground ...The permanent displacement of seismic slopes can be regarded as an effective criterion for stability estimation. This paper studied the characteristics of permanent displacements induced by velocity pulse-like ground motions and developed an empirical model to readily evaluate the stability of seismic slopes in a near-fault region. We identified 264 velocity pulse-like ground motions from the Next Generation Attenuation(NGA) database using the latest improved energy-based approach. All selected ground motions were rotated to the orientation of the strongest observed pulse for considering the directivity of the pulse effect, so that the most dangerous condition for slopes was considered. The results show the velocity pulse-like ground motions have a much more significant effect on permanent displacement of slopes than non-pulse-like ground motions. A regression model based on a function of peak ground velocity(PGV), peak ground acceleration(PGA) and critical acceleration(ac), was generated. A significant difference was found by comparing the presented model with classical models from literatures. This model can be used to evaluate the seismic slope stability considering the effects of nearfault pulse-like characteristics.展开更多
基金supported by General Program of National Natural Science Foundation of China(61773080)China Central Universities Foundation(2019CDYGZD001)+1 种基金Scientific Reserve Talent Programs of Chongqing University(cqu2018CDHB1B04)Graduate Research and Innovation Foundation of Chongqing(CYB20065)。
文摘In this paper,a novel remaining useful life prediction approach considering fault effects is proposed.The Wiener process is used to construct the degradation process of single performance characteristic with the fault effects.The first passage time based remaining useful life distribution is calculated by assuming fault occurrence moment is a random variable and follows a certain distribution.Expectation maximization algorithm is employed to estimate model parameters,where the fault occurrence moment is considered as a missing data.Finally,a Copula function is used to describe the dependence between the multiple performance characteristics and derive joint remaining useful life(RUL)distribution of product with the fault effects.The effectiveness of the proposed approach is verified by the experiments of turbofan engines.
文摘Infill walls that are considered for the design phase of RC buildings completely change damage mechanisms.In such cases,field studies conducted after destructive earthquakes show that the damage is advanced,especially in structures without infilling walls on the ground floors.The same situation was observed in destructive earthquakes such as the 2023 Kahramanmaras earthquake.The main goal of this study is to examine the effect of the infill wall situation on the behavior of structures in earthquakes and to examine how the near-fault effect will change the damage levels of structures with and without infill walls.In this context,the effect of the infill wall situation was examined by utilizing the Kahramanmaras earthquake data.As a result of the study,it was observed that designs with infill wall building models gave better results compared to the other models.The near fault effect was observed to be more dominant in building models without infill walls and with open stories.In conclusion,the infill walls was positively affected with regard to the near fault effect and the features of the building,such as period values,ground story behavior,story shear forces,column moment values,inter-story drift ratio,and base shear forces on ground floors,and increased base shear force.
基金financially supported by the National Key Research and Development Program of China(No.2016YFB0701202)the National Natural Science Foundation of China(General Program No.51474149 and Key Program No.51631006)
文摘Generalized stacking-fault energies （GSFEs） of basal-plane stacking faults 11 and 12 in Mg alloys have been studied based on first-principles calculations, where 43 alloying elements were considered. It is found that the most contributing features of alloying elements to GSFEs are bulk modulus, equilibrium volume, binding energy, atomic radius and ionization energy. Both bulk modulus and ionization energy exhibit positive relationships with GSFEs, and the others show opposite relationships. Multiple regressions have been performed to offer a quantitative prediction for basal-plane GSFEs in Mg-X systems. GSFEs, alloying effects of elements and the prediction model established within this work may provide guidelines for new Mg alloys design with better ductility.
基金Federal Highway Administration(FHWA) Under Grant No.DTFH41-98900094
文摘In the 1990s, several major earthquakes occurred throughout the world, with a common observation that near fault ground motion （NFGM） characteristics had a distinct impact on causing damage to civil engineering structures that could not be predicted by using far field ground motions. Since then, seismic responses of structures under NFGMs have been extensively examined, with most of the studies focusing on structures with relatively short fundamental periods, where the traveling wave effect does not need to be considered. However, for long span bridges, especially arch bridges, the traveling wave （only time delay considered） effect may be very distinct and is therefore important. In this paper, the results from a case study on the seismic response of a steel arch bridge under selected NFGMs is presented by considering the traveling wave effect with variable apparent velocities. The effects of fling step and long period pulses of NFGMs on the seismic responses of the arch bridge are also discussed.
文摘Many destructive earthquakes happened in Tehran, Iran in the last centuries. The existence of active faults like the North Tehran is the main cause of seismicity in this city. According to past investigations, it is estimated that in the scenario of activation of the North Tehran fault, many structures in Tehran will collapse. Therefore, it is necessary to incorporate the near field rupture directivity effects of this fault into the seismic hazard assessment of important sites in Tehran. In this study, using calculations coded in MATLAB, Probabilistic Seismic Hazard Analysis （PSHA） is conducted for an important site in Tehran. Following that, deaggregation technique is performed on PSHA and the contribution of seis- mic scenarios to hazard is obtained in the range of distance and magnitude. After identifying the North Tehran fault as the most hazardous source affecting the site in 10000-year return period, rupture directivity effects of this fault is incorporated into the seismic hazard assessment using Somerville et al. （1997） model with broadband approach and Shahi and Baker （2011） model with narrowband approach. The results show that the narrowband approach caused a 27% increase in the peak of response spectrum in 10000-year return period compared with the conventional PSHA. Therefore, it is necessary to incorporate the near fault rupture directivity effects into the higher levels of seismic hazard assessment attributed to important sites.
基金supported by the National Key Research and Development Program of China(No. 2016YFB0300801)the National Natural Science Foundation of China(Nos.11427806,51471067,51371081,51671082 and 51601060)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20120161110036)the Hunan Provincial Natural Science Foundation of China(No.14JJ4052)
文摘Intrinsic stacking-fault energy is a critical parameter influencing the various mechanical performances of aus- tenitic steels with high Mn concentrations. However, quantitative calculations of the stacking-fault energy （SFE） of the face-centered cubic （fcc） Fe, including the changes in concentrations and geometrical distribution of alloying atoms, cannot be obtained by using previous computation models. On the basis of the interaction energy model, we evaluated the effects of a single alloying atom （i.e., Mn, A1, Si, C and N）, as well as its aggregates, including the Mn-X dimer and Mn2-X trimer （X = A1, Si, C and N） on the SFE of the fcc Fe via first-principle calculations. Given low concentrations （〈10 wt%） of alloying atoms, dimers and trimers, theoretical calculations reveal the following： （1） Alloying atom Mn causes a decrease in the SFE, whereas A1, Si, C and N significantly increase the SFE; （2） combination with other alloying atoms to form the Mn-X dimer （X = A1, Si, C and N） exerts an effect on SFE that, to a certain extent, is close to that of the corresponding single X atom; （3） the interaction between Mnz-X and the stacking fault is stronger than that of the corresponding single X atom, inducing a significant increase in the SFE of fcc Fe. The theoretical results we obtained demonstrate that the increase in SFE in high-Mn steel originates from the synergistic effect of Mn and other trace alloy atoms.
文摘There are four types of metamorphic rocks in the Marinwobo fault, i.e, cataclasite, mylonite, mictosite and migmatitic granite, and the formation of these rocks is due to the progressive metamorphism of the pyroclastics. The fluids play a very important role in the metamorphic process of these rocks in the Marinwobo fault, the most important feature is that the fluids not only result in the migration of the major elements of the deformation rocks, but also result in the volume loss of the deformation rocks in the deformation process. Thus the migration laws of the major elements in different stages of the progressive metamorphic process are discussed according to mass balance equations. Finally, the quantitative analysis of the mass loss and volume loss of the different rocks the in Marinwobo fault is discussed in this paper.
基金Basic Science Research Foundation of Institute of Engineering Mechanics, China Earthquake Administration (2006B07) Natural Science Foundation of Heilongjiang Province (E2007-13)Joint Seismological Science Foundation of China (C07025)
文摘Root-mean-square distance Drms with characteristic of weighted-average is introduced in this article firstly. Drms can be used to capture the general proximity of a site to a dipping fault plane comparing with the rupture distance Drup and the seismogenic distance Dseis. Then, using Drup, Dseis and Drms, the hanging wall/footwall effects on the peak ground acceleration (PGA) during the 1999 Chi-Chi earthquake are evaluated by regression analysis. The logarithm residual shows that the PGA on hanging wall is much greater than that on footwall at the same Drup or Dseis when the Drup or Dseis is used as site-to-source distance measure. In contrast, there is no significant difference between the PGA on hanging wall and that on footwall at the same Drms when Drms is used. This result confirms that the hanging wall/footwall effect is mainly a geometric effect caused by the asymmetry of dipping fault. Therefore, the hanging wall/footwall effect on the near-fault ground motions can be ignored in the future attenuation analysis if the root-mean-square distance Drms is used as the site-to-source distance measure.
文摘In this paper, the reservoir temperatures of 14 hot spring samples collected from the northern segment of theRed River Fault are calculated by using the mixing-model of SiO2-geothermometer. Based on the features ofreservoir temperatures and densities of hot springs, the northern segment of the Red River Fault is furtherdivided into 4 sub-segments. The influence of weakening effect of water on seismic activities is discussed fromthe view point of fault-weakening effect of water. It is suggested that the difference in seismic activity between various sub-segments is principally caused by the difference in intensity of the fault-weakening effect ofwater of these sub-segments. The Eryuan sub-segment where the reservoir temperatures are high and the hotsprings are dense corresponds to a slipped region, however, the Jianchuan and Midu sub-segments where thereservoir temperatures are lower and the hot springs are fewer as well as the Dan sub-segment where the hotspring are very few all correspond to locked regions. It is suggested that Dan sub-segment is the riskiest region for strong earthquake preparation, while the possibility for strong earthquake preparation is very little inthe Eryuan sub-segment.
基金funded by the Major Basic Research and Development Program of China(No.2014CB046905)the Ph.D.Programs Foundation of Ministry of Education of China(No.20130095110018)
文摘Based on the stress field distribution rule of the mining floor under abutment pressure, we have established a simplified mechanical model, which contains multiple factors relating to activation and evolution of insidious water-conductive faults. The influence of normal and shear stresses on fault activation and effective shear stress distribution in the fault plane was acquired under mining conditions.Using fracture mechanics theory to calculate the stress intensity factor of an insidious fault front, we have derived the criterion for main fault activation. Results indicate that during the whole working face advance, transpressions are exerted on fault planes twice successively in opposite directions. In most cases, the second transpression is more likely to lead to fault activation. Activation is influenced by many factors, predominant among which are: burial depth of the insidious fault, friction angle of the fault plane, face advance direction and pore water pressure. Steep fault planes are more easily activated to induce a sustained water inrush in the face.
基金China Science Foundation of Postdoctoral Program (20060400826)China National Science Foundation of the International (Regional) Cooperative Research Program (50420120133).
文摘Ground motions with forward-directivity effect in the near-fault region are obviously different from ordinary far-field ground motions. Design spectral models for this kind of motions have been proposed by correlating simple pulses with parameters attenuation relationships in a previous study of the authors. To further test the applica- bility of the established design spectral model, we analyze ground motion pseudo-velocity response spectra （PVS）, normalized pseudo-velocity spectra （NPVS） and bi-normalized pseudo-velocity spectra （BNPVS） of 53 typical near-fault forward-directivity ground motions. It is found that BNPVS not only has more salient features to reflect the difference between soil and rock sites, but also has less scattering to reveal the nature of forward-directivity motions. And then, BNPVS is used for prediction of design spectra accounting for the influence of site conditions, and the constructed design spectra are compared with those spectra established previously. It is concluded that site condition can heavily affect ground motions, buildings on rock can be even more dangerous than those on soil sites, in particular for ordinary buildings with short to middle vibration periods. Finally, pulse models are also suggested for structural analyses in the near-fault region.
基金National Natural Science Foundation of China (50278002)Dalian Nationalities University Ph D Foundation (20066104)
文摘It was shown from the study on the recently near-fault earthquake ground motions that the near-fault effects were seldom considered in the existing Chinese seismic code. Referring to the UBC97 design concept for near-fault factors, based on the collected world-widely free-site records of near-fault earthquakes ground motions classified by earthquake magnitude and site condition, the attenuation relationship expressions of the acceleration spectrum demand at the key points within the long period and moderate period were established in term of the earthquake magnitude and the site condition. Furthermore, the near-fault factors＇ expressions about the earthquake magnitude and the fault distance were deduced for the area lack of near-fault strong earthquake records. Based on the current Chinese Building Seismic Design Code, the near-fault effect factors and the modified design spectral curves, which were valuable for the seismic design, were proposed to analyze the seismic response of structures.
基金supported by the National Natural Science Foundation of China(11372073,11072061)
文摘Since the joint actuator of the space robot executes the control instructions frequently in the harsh space environment,it is prone to the partial loss of control effectiveness(PLCE)fault.An adaptive fault-tolerant control algorithm is designed for a space robot system with the uncertain parameters and the PLCE actuator faults.The mathematical model of the system is established based on the Lagrange method,and the PLCE actuator fault is described as an effectiveness factor.The lower bound of the effectiveness factors and the upper bound of the uncertain parameters are estimated by an adaptive strategy,and the estimated value is fed back to the control algorithm.Compared with the traditional fault-tolerant algorithms,the proposed algorithm does not need to predetermine the lower bound of the effectiveness factor,hence it is more in line with the actual engineering application.It is proved that the algorithm can guarantee the stability of the closed-loop system based on the Lyapunov function method.The numerical simulation results show that the proposed algorithm can not only compensate for the uncertain parameters,but also can tolerate the PLCE actuator faults effectively,which verifies the effectiveness and superiority of the control scheme.
文摘Since the early 1970s tremendous growth has been seen in the research of software reliability growth modeling. In general, software reliability growth models （SRGMs） are applicable to the late stages of testing in software development and they can provide useful information about how to improve the reliability of software products. A number of SRGMs have been proposed in the literature to represent time-dependent fault identification / removal phenomenon; still new models are being proposed that could fit a greater number of reliability growth curves. Often, it is assumed that detected faults are immediately corrected when mathematical models are developed. This assumption may not be realistic in practice because the time to remove a detected fault depends on the complexity of the fault, the skill and experience of the personnel, the size of the debugging team, the technique, and so on. Thus, the detected fault need not be immediately removed, and it may lag the fault detection process by a delay effect factor. In this paper, we first review how different software reliability growth models have been developed, where fault detection process is dependent not only on the number of residual fault content but also on the testing time, and see how these models can be reinterpreted as the delayed fault detection model by using a delay effect factor. Based on the power function of the testing time concept, we propose four new SRGMs that assume the presence of two types of faults in the software： leading and dependent faults. Leading faults are those that can be removed upon a failure being observed. However, dependent faults are masked by leading faults and can only be removed after the corresponding leading fault has been removed with a debugging time lag. These models have been tested on real software error data to show its goodness of fit, predictive validity and applicability.
文摘The plane-wave assumption for incident SH waves can be a good approximation for cylindrical and spherical waves radiated from finite sources, even when the source is as close as twice the size of the inhomogeneity, and when the source and the inhomogeneity are described within the same coordinate system. However, in a more general setting, and when the fault＇s radiation pattern must be considered, the plane-wave approximation may not yield satisfactory answers for arbitrary orientation of the fault. Jalali et al. （2015） demonstrated this for a semi-cylindrical, sedimentary valley, and in this study we extend their results to a case in which the semi-circular, sedimentary valley is replaced by a canyon. We describe the effects of incident cylindrical waves on the amplitudes of surface motion in and near the semi-cylindrical canyon when the causative faults are at different distances and have different curvatures and orientations.
文摘The alluvial fan of the Shahdad in Derakt-Tangan River is one of the biggest alleviation in total dry area in the north eastern Kerman. This alluvial fan is formed effected by different materials erosion in drainage basin of Derakt-Tangan River and laying these materials in the final part of this drainage basin called Lut. Tectonics activate with efficacy in the place of the settlement of the alluvial fan. The region, which is being studied, is one of the active tectonic regions. The severe tectonic activities in the studying region have been proved by several observations. One of the most important evidences in the region is the various faults in the area and implies to fan alluvium （from head to end）, study line profile in past and present. The most important fault of the region is the great fault of ＂Nay band＂, the southern fault of Shahdad and the series of faults having the direction of north-western to south-eastern and northern and southern. The drainage basin of alluvial fan of the Derakt-Tangan River leads from east to Kavir-lut, from west to the Baghe-Bala Mountains and Kalisaky from The aim of this article is the morphology of Derakt-Tangan north to the altitutes of Dahran and from south to the mountains of Jeffan river fan indicative on neotectonics in the region.
基金supported by the National 973 Basic Research Program (Grant No.2006CB202308)the Major National Science & Technology Program (2008ZX05008-004-012)
文摘Understanding hydrocarbon migration and accumulation mechanisms is one of the key scientif ic problems that should be solved for effective hydrocarbon exploration in the superimposed basins developed in northwest China. The northwest striking No.1 slope break zone, which is a representative of superimposed basins in the Tarim Basin, can be divided into five parts due to the intersection of the northeast strike-slip faults. Controlled by the tectonic framework, the types and properties of reservoirs and the hydrocarbon compositions can also be divided into five parts from east to west. Anomalies of all the parameters were found on the fault intersection zone and weakened up-dip along the structural ridge away from it. Thus, it can be inferred that the intersection zone is the hydrocarbon charging position. This new conclusion differs greatly from the traditional viewpoint, which believes that the hydrocarbon migrates and accumulates along the whole plane of the No.1 slope break zone. The viewpoint is further supported by the evidence from the theory of main pathway systems, obvious improvement of the reservoir quality （2-3 orders of magnitude at the intersection zone） and the formation mechanisms of the fault intersection zone. Differential hydrocarbon migration and entrapment exists in and around the strike- slip faults. This is controlled by the internal structure of faults. It is concluded that the more complicated the fault structure is, the more significant the effects will be. If there is a deformation band, it will hinder the cross fault migration due to the common feature of two to four orders of magnitude reduction in permeability. Otherwise, hydrocarbons tend to accumulate in the up-dip structure under the control of buoyancy. Further research on the internal fault structure should be emphasized.
文摘A numerical model for generating normal fault earthquakes in the Qinghai-Xizang Plateau′S upper crust is constructed with 3-D elasto-viscous finite element method. Based on the numerical simulation calculation,some conclusions were got:If the effective viscosity of the upper crust material is less than that of lower strata of the crust in the Qinghai-Xizang Plateau, even under the strong push of India continent,the stress state of the upper crust can still be extensional in south part of the Qinghai-Xizang Plateau.Numerical simulations show that the stress state changes with the depth of the lithosphere,from extensional stress state in upper crust to compressive in the lower part.Extensional stress state may exist mainly in the upper crust of the south part of the Qinghai-Xizang Plateau.
基金The National Scientifi c and Technological Support Project of MST Under Grant No. 2006BAC13B02-0106the Special Research Fund for the Public Institute of China, IGP,CEA Under Grant No. DQJB06A01
文摘Based on the performance of submarine cables in past earthquakes, an analytical method to determine cable performance under seabed fault movement is proposed in this paper. First, common types of earthquake damage to submarine cables are summarized, which include seabed displacement induced by fault movement, submarine landslides and seabed soil liquefaction, etc. The damage is similar to damage observed to buried pipelines following land earthquakes. The Hengchun earthquake of Dec. 26, 2006 is used as a case study. The M7.2 earthquake occurred in the South China Sea at 20：26 Beijing Time, and caused 14 international submarine cables to sever and break. The results show that the proposed method predicts damage similar to that observed in the Hengchun earthquake. Based on parametric studies of the influence of the water depth and the magnitude of the submarine earthquake, countermeasures to prevent damage to submarine cables are proposed.
基金financial support from the National Natural Science Foundation of China (41672286, 41761144080 and 41530639)Science &Technology Department of Sichuan Province (2017JQ0042)+2 种基金Ministry of Science and Technology of China (KY201801005)State Key Laboratory for GeoMechanics and Deep Underground Engineering, China University of Mining & Technology (SKLGDUEK1806)Innovation-Driven Project of Central South University (No. 2019CX011)
文摘The permanent displacement of seismic slopes can be regarded as an effective criterion for stability estimation. This paper studied the characteristics of permanent displacements induced by velocity pulse-like ground motions and developed an empirical model to readily evaluate the stability of seismic slopes in a near-fault region. We identified 264 velocity pulse-like ground motions from the Next Generation Attenuation(NGA) database using the latest improved energy-based approach. All selected ground motions were rotated to the orientation of the strongest observed pulse for considering the directivity of the pulse effect, so that the most dangerous condition for slopes was considered. The results show the velocity pulse-like ground motions have a much more significant effect on permanent displacement of slopes than non-pulse-like ground motions. A regression model based on a function of peak ground velocity(PGV), peak ground acceleration(PGA) and critical acceleration(ac), was generated. A significant difference was found by comparing the presented model with classical models from literatures. This model can be used to evaluate the seismic slope stability considering the effects of nearfault pulse-like characteristics.
