Implementing acoustic emission experiments with large rock samples, LURR (Load/Unload Response Ratio) theory was studied. The loading conditions in the experiments were designed to simulate the complicated loading pro...Implementing acoustic emission experiments with large rock samples, LURR (Load/Unload Response Ratio) theory was studied. The loading conditions in the experiments were designed to simulate the complicated loading process of underground rocks. The damages emerging inside the rock samples were recorded by the acoustic emission technique during the loading process. The experimental results were consistent with prediction by LURR theory. Integrating the changing processes of LURR value Y and the location process of acoustic emission events showed agreement between the variation of LURR value Y and the damage evolution inside the rocks. Furthermore, the high value of Y emerged before the complete breakdown of materials. Therefore, the damage evolution of rock specimen can be quantitatively analyzed with LURR theory, thus the failure of the rock materials and the earthquake occurrence may be predicted. The experimental results gave a further verification of LURR theory.展开更多
It is well known that the deformation and damage of reservoir colluvium landslides are often determined by the combined dynamics of reservoir water level change and rainfall.Based on the systematic analysis of the cha...It is well known that the deformation and damage of reservoir colluvium landslides are often determined by the combined dynamics of reservoir water level change and rainfall.Based on the systematic analysis of the change law of reservoir water level,rainfall and displacements of reservoir colluvium landslide,this paper proposes the compound hydrodynamic action of rainfall and reservoir water as the unload-load parameter,and the landslide displacement as the unload-load response parameter.Based on this,a physical prediction model of the compound hydrodynamic unload-load response ratio of reservoir colluvium landslide was established,and the quantitative relationship between the compound hydrodynamic unload-load response ratio and its stability evolution was in-depth analyzed and determined.On the basis of the above research,taking Shuping landslide,a typical hydrodynamic pressure landslide as an example,the unload-load response ratio model is used to systematically evaluate and predict the stability evolution law and the change trend of the landslide under compound hydrodynamic action.The prediction result shows that the variation law of the compound hydrodynamic unload-load response ratio is consistent with the dynamic evolution law of its stability.Therefore,the above studies show that the compound hydrodynamic unload-load response ratio parameter is an effective displacement dynamic evaluation parameter for reservoir colluvium landslides,so it can be used in the prediction of the reservoir colluvium landslides.展开更多
Rock experiment results indicate that the load/unload response ratio (LURR) of rocks expressed via strain energy may have singular or negative value after the stress in the rock reaches its maximum before rock failure...Rock experiment results indicate that the load/unload response ratio (LURR) of rocks expressed via strain energy may have singular or negative value after the stress in the rock reaches its maximum before rock failure or when the rock goes into the strain-weakening phase. The universality of this phenomenon is discussed. Expressed via strain or strain energy and the travel time of P wave, the variation form of the reciprocal of LURR during the process of rock failure preparation is derived. The results show that after a sharp decrease the reciprocal of LURR reaches its minimum when the main fracture of the rock is about to appear. This feature can be taken as an indication that the rock main fracture is impending.展开更多
In this paper, the tempo-spatial evolution characteristics of the load/unload response ratio (namely LURR or Y value) before strong earthquakes with magnitude over 6 during 1976~1994 in California of America are studi...In this paper, the tempo-spatial evolution characteristics of the load/unload response ratio (namely LURR or Y value) before strong earthquakes with magnitude over 6 during 1976~1994 in California of America are studied in detail. The results show that there appear some high-Y regions cohering with the regional tectonic trend in a great area 3~4 years before strong earthquakes and these high-Y regions migrate from the periphery to the epicenter region at a speed of tens of kilometers per year. The load/unload response ratio (LURR) anomalies near the epicenter region characterizes a type of (ascend ? descend( and appear and increase steeply until one year or less before most earthquakes. (Positive( earthquakes form usually a concentration area; in and near which the main shock occurs. We have analyzed the different and same characters of earthquakes between California of American and the Chinese mainland. Basing on these results, we discuss the approach and method how to predict and estimate the three parameters (place, time and magnitude) of a strong earthquake in California of American by applying the characteristics of the LURR.展开更多
The variation of Load/Unload Response Ratio (LURR) against time for earthquakes in Kerman Province, Iran, on February 22, 2005, M6.4 and in Lorestan Province, Iran, on March 31, 2006, M6.1, has been calculated and ana...The variation of Load/Unload Response Ratio (LURR) against time for earthquakes in Kerman Province, Iran, on February 22, 2005, M6.4 and in Lorestan Province, Iran, on March 31, 2006, M6.1, has been calculated and analysed in this paper. The tempo-spatial scanning of LURR in the region of Iran during January 1, 2003 to March 31, 2006 has been conducted, with 1 year as a time-window, 1 month as a time-step, and the comparison of the LURR anomalous regions in 2004 with the actual earthquakes with M≥5.0 in the next year (2005) is also given, which shows that 11 earthquakes with M≥5.0 occurred in LURR anomalous regions while 12 earthquakes with M≥5.0 in LURR regions in 2005. Furthermore, the seismicity in this region is studied by investigating the evolvement of the anomalous LURR regions.展开更多
BACKGROUND Gastric cancer(GC)has a relatively high incidence and mortality rate.Surgery is the primary treatment;however,the survival rate of patients remains low.Therefore,there is an urgent need to identify simple a...BACKGROUND Gastric cancer(GC)has a relatively high incidence and mortality rate.Surgery is the primary treatment;however,the survival rate of patients remains low.Therefore,there is an urgent need to identify simple and feasible prognostic indicators for GC.As an inflammation-related biomarker,the systemic inflammation response index(SIRI),platelet-to-lymphocyte ratio(PLR),and SIRI-PLR can be obtained from routine blood tests.Compared with existing prognostic indicators,which are expensive and rely on complex analyses,SIRI-PLR offers extremely high convenience and cost-effectiveness.AIM To explore the impact of SIRI-PLR on the prognosis of patients with stage I–III GC after surgery and construct a nomogram.METHODS We retrospectively analyzed the clinical and pathological data of patients with GC who underwent radical surgery at The First Affiliated Hospital of Anhui Medical University between January 2014 and December 2017.A total of 1071 patients with clear clinical prognoses were selected.Univariate and multivariate Cox regression analyses were performed to identify independent prognostic factors associated with overall survival in patients with GC,and a nomogram prediction model was constructed.RESULTS Multivariate Cox regression analysis revealed that age,tumor size,T stage,N stage,SIRI-PLR,and carcinoembryonic antigen were independent prognostic factors.The areas under the curve of the nomogram for training and validation sets were 0.821 and 0.848,respectively.Calibration plots and decision curve analyses demonstrated that the nomogram exhibited good predictive performance and clinical utility in training and validation cohorts.CONCLUSION Preoperative SIRI-PLR was significantly associated with the prognosis of patients with stage I–III GC following radical gastrectomy.Our nomogram could serve as an essential tool for clinicians to predict the postoperative prognosis of patients with stage I–III GC.展开更多
In this paper, through the nonlinear response of rock strain and stress, we have analized the physical mechanism of loading and unloading response ratio of the well level to the earth tides,the respouse of an aquife...In this paper, through the nonlinear response of rock strain and stress, we have analized the physical mechanism of loading and unloading response ratio of the well level to the earth tides,the respouse of an aquifer of confined well to bulk strain tide and showed two methods of the calculation of loading and unloading response ratio of the well level to the earth tides. We took the example of the Yu 01 well, which is near the epicenter of Heze M S 5.9 earthquake, calculated the response rate and loading and unloading response ratio of two kinds of the earth tides of it. The response rate and response ratio before the earthquake had the variation of increase.展开更多
The spatial temPOral evolution characteristics of the load/unload response ratio (Y) before strong earthquakes is studied in this paper. The results show that the regions of high value of Y migrate and converge to the...The spatial temPOral evolution characteristics of the load/unload response ratio (Y) before strong earthquakes is studied in this paper. The results show that the regions of high value of Y migrate and converge to the impending earthquake epicenter from different directions before the occurrence of the event. Basing on this discovery, it is proposed that the method can be used to predict the three elements of an earthquake. It was applied to predict that an earthquake would occur in the western part of Yunnan Province, southwestern China. The three elements (time, space and magnitude) of the Menglian earthquake with Ms7.3 which occurred on July 12, 1995 in Yunnan Province tallied with our prediction.展开更多
In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(...In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(V/H) were investigated using the ground motion recordings from the K-NET network and the seafloor earthquake measuring system(SEMS).The results indicate that the vertical component of offshore motions is lower than that of onshore motions.The V/H PGA ratio of acceleration time histories at offshore stations is about 50%of the ratio at onshore stations.The V/H for offshore ground motions is lower than that for onshore motions,especially for periods less than 0.8 s.Furthermore,based on the results in statistical analysis for offshore recordings in the K-NET,the simplified V/H design equations for offshore motions in minor and moderate earthquakes are proposed for seismic analysis of offshore structures.展开更多
Plant invasion alters the fundamental structure and function of native ecosystems by affecting the biogeochemical pools and fluxes of materials and energy. Native(Suaeda salsa) and invasive(Spartina alterniflora) salt...Plant invasion alters the fundamental structure and function of native ecosystems by affecting the biogeochemical pools and fluxes of materials and energy. Native(Suaeda salsa) and invasive(Spartina alterniflora) salt marshes were selected to study the effects of Spartina alterniflora invasion on soil organic carbon(SOC) contents and stocks in the Yellow River Delta. Results showed that the SOC contents(g/kg) and stocks(kg/m^2) were significantly increased(P < 0.05) after Spartina alterniflora invasion of seven years, especially for the surface soil layer(0–20 cm). The SOC contents exhibited an even distribution along the soil profiles in native salt marshes, while the SOC contents were gradually decreased with depth after Spartina alterniflora invasion of seven years. The natural ln response ratios(Ln RR) were applied to identify the effects of short-term Spartina alterniflora invasion on the SOC stocks. We also found that Spartina alterniflora invasion might cause soil organic carbon losses in a short-term phase(2–4 years in this study) due to the negative Ln RR values, especially for 20–60 cm depth. And the SOCD in surface layer(0–20 cm) do not increase linearly with the invasive age. Spearman correlation analysis revealed that silt + clay content was exponentially related with SOC in surface layer(Adjusted R^2 = 0.43, P < 0.001), suggesting that soil texture could play a key role in SOC sequestration of coastal salt marshes.展开更多
Load-Unload Response Ratio (LURR) is a new promising approach to earthquake prediction. In the previous years, a series of successful medium-term predictions have been made for strong earthquakes on the Chinese mainla...Load-Unload Response Ratio (LURR) is a new promising approach to earthquake prediction. In the previous years, a series of successful medium-term predictions have been made for strong earthquakes on the Chinese mainland using this method. In order to investigate whether the LURR method applies to different tectonic regimes, i.e., whether it is universal, the San Andreas Fault and its vicinities are chosen as the study region in this paper. The spatial variation of LURR in the western United States (30°～50°N, 100°～130°W) is studied in detail and the earthquake tendency in this region is discussed based on historic earthquake cases.展开更多
Previous studies have shown that the active tectonic block boundaries in the Chinese mainland are the main belts and concentration areas of strong earthquakes occurring in the Chinese mainland.It is essential to carry...Previous studies have shown that the active tectonic block boundaries in the Chinese mainland are the main belts and concentration areas of strong earthquakes occurring in the Chinese mainland.It is essential to carry out follow-up analysis of strong earthquake risk of active tectonic block boundaries.In this paper,we carry out the analysis on the tendency of strong earthquakes along each active tectonic block boundary from three aspects respectively,including the evolutionary characteristics of the Load/Unload Response Ratio time series,the probability method based on the log-normal distribution function,and variation of b value.The estimation of strong earthquake criticality on each active tectonic block boundary is done based on the evolutionary characteristics of the Load/Unload Response Ratio time series,the cumulative probability and conditional probability,and the decrease of the b value.Finally,according to the results of analyses on the above three aspects,the potential strong earthquake areas in the forthcoming 5 years in the Chinese mainland are discussed.展开更多
The existence of the principal directions of the ground motion based on Arias intensity is well-known. These principal directions do not necessarily coincide with the orientations of recording sensors or with the orie...The existence of the principal directions of the ground motion based on Arias intensity is well-known. These principal directions do not necessarily coincide with the orientations of recording sensors or with the orientations along which the ground motion parameters such as the peak ground acceleration and the pseudo-spectral acceleration （PSA） are maximum. This is evidenced by the fact that the maximum PSA at different natural vibration periods for horizontal excitations do not correspond to the same orientation. A recent analysis carried out for California earthquake records suggests that an orientation-dependent ground motion measurement for horizontal excitations can be developed. The main objective of this study is to investigate and provide seismic ground motion measurements in the horizontal plane, including bidirectional horizontal ground motions, for Mexican interplate and inslab earthquake records. Extensive statistical analyses of PSA are conducted for the assessment. The analysis results suggest that similar to the case of California records, the average behavior of the ratio of the PSA to the maximum resulting PSA can be approximated by a quarter of an ellipse in one quadrant; and that the ratio can be considered to be independent of the value of the maximum resulting PSA, earthquake magnitude, earthquake distance and the focal depth. Sets of response ratios and attenuation relationships that can be used to represent a bidirectional horizontal ground motion measurement for Mexican interplate and inslab earthquakes were also developed.展开更多
Vulnerability to natural disasters falls into three categories： exposure, resistance, and resilience, where resilience mainly refers to the capability of a pressure-bearing system to recover by returning to its initi...Vulnerability to natural disasters falls into three categories： exposure, resistance, and resilience, where resilience mainly refers to the capability of a pressure-bearing system to recover by returning to its initial state, that is, the ability to adapt to disaster pressure. Resilience is a major subject of research on disaster prevention and mitigation. This research mainly focuses on the ability of the hydraulic structure to recover from the significant impacts of typhoons. According to the load/unload response ratio theory, the degree of instability by which nonlinear systems can be identified according to the difference between load and unload responses was analyzed. This analysis was used as a basis to study the resilience of a hydraulic structure. Taking the Yangtze River embankments under the impact of Typhoon Matsa as an example, the ability of the typical sections of different types of embankments to adapt to the significant impact of the typhoon, i.e., the resilience of the hydraulic structure, is described with the help of the load/unload response ratio （L）. The results of the calculated resilience reflect the actual conditions of the structure and can be used to determine the applicability of the embankment section. The load/unload response ratio theory is one of the effective tools for calculating the resilience of hydraulic structures under the significant impacts of typhoons.展开更多
This paper studies the evolution charateristics of positive and negative quakes before Hyugo earthquake of M =7.2 and several strong quakes in Kanto area in Japan.The results show that the earthquakes over a certai...This paper studies the evolution charateristics of positive and negative quakes before Hyugo earthquake of M =7.2 and several strong quakes in Kanto area in Japan.The results show that the earthquakes over a certain megnitude are mainly positive ones a certain time before the main shock in or near the focal regions of most strong quakes,and form a concentratingintervals of positive quakes,The main quakes generally locate in or near the areas of positive quake distribution.Negative quakes often occur several months before the main shocks (not excluding positive ones), with the decrease of LURR (Loading/Unloading Response Ratio) values.It possibly shows that earthquake generating process has come to a short term stage.These characteristics may help to predict the time and location of the future earthquakes,and have been applied to the preliminary prediction of the time and the location of the earthquake of M =6.6 on Sep.11,1996 in Kanto area.展开更多
We use the Centroid Moment Tensor （CMT） solution of the earthquakes occurred in Chile subduction to analyze the characteristics of focal mechanisms. We define the,angle between P, B, and T axes of focal mechanisms a...We use the Centroid Moment Tensor （CMT） solution of the earthquakes occurred in Chile subduction to analyze the characteristics of focal mechanisms. We define the,angle between P, B, and T axes of focal mechanisms and three stress axes of tectonic stress field as the consistency parameter, to research the dynamic changes of focal mechanism pattern in earthquake preparation area before the 2010 Maule, Chile earthquake. The result shows that the consistency parameter decreases before the earthquake, and the area of the lower consistent parameter visually coincides with the distribution of aftershocks. This phenomenon is similar to the Load-Unload Response Ratio （LURR） decreases prior to the occurrence of macro-fracture happened in the acoustic emission experiments involving large rock specimens under tri-axial stress.展开更多
According to the epicenter distance and the site classification, the 404 groups of earthquake recordings of the main shock of the Chi-Chi, Taiwan China earthquake in 1999 are catalogued. Based on these data, we analyz...According to the epicenter distance and the site classification, the 404 groups of earthquake recordings of the main shock of the Chi-Chi, Taiwan China earthquake in 1999 are catalogued. Based on these data, we analyze the statistical features of duration, PGA, envelopes and the response spectra ratio of the horizontal and vertical components of the acceleration recordings. The results of these analyses show that the effect of site classification on the acceleration of various components is obvious; furthermore, fault direction also has certain effects on the characteristics of the horizontal components of ground motion. The detailed research results are as follows： （ 1 ） the duration of the horizontal components of acceleration records increases with the softening of the site; （2） the direction of fault slip has some effects on PGA＇s attenuation features; （3） the average envelopes of acceleration records at different distances and site dames are basically single peak functions of time and the envelopes of horizontal and vertical components of ground motion are obviously different; （4） with the same epicenter distance, EW/NS response spectrum ratios tend to approximate 1.0 as the site becomes softer and the period shorter. V/H response spectrum ratios in short periods （〈 0. 1s） increase with the softening of site, however, V/H ratios within the long-period range （ 〉 characteristic period） decrease with the softening of the site, and the decrease of V/EW ratio speeds up relatively.展开更多
The high-speed railway track-bridge system(HSRTBS)is susceptible to damage under the effects of earthquakes,thus threatening the safety of running trains.To improve the seismic performance of HSRTBS and reduce damage ...The high-speed railway track-bridge system(HSRTBS)is susceptible to damage under the effects of earthquakes,thus threatening the safety of running trains.To improve the seismic performance of HSRTBS and reduce damage to the system,a replaceable X-shaped Energy Dissipating Steel Damper(X-EDSD)is proposed,which contains the energy-dissipating component(EDC)to dissipate the earthquake energy.Cyclic tests were performed to obtain the hysteretic performance of the EDC and X-EDSD,and a test-validated numerical model was developed to conduct parametric analyses.The X-EDSD was simplified as a nonlinear spring element with hysteretic parameters and modeled into the numerical model of the HSRTBS for seismic dynamic analyses.The peak displacements of girder and rail decreased by approximately 48.1%and 47.7%,respectively.The peak deflections of the fasteners,cement asphalt mortar layer and sliding layer were reduced by 70.4%,70.8%,and 86.1%,respectively.A comprehensive consideration of the system response control-economic cost ratio coefficient R_(pe)is proposed,and the optimal thickness of 14.94 mm is obtained by applying cubic term coefficient fitting according to 5 groups of steel plate thickness data for the specific case study in this paper.The method can be used for cost-informed X-EDSD-selection for seismic mitigation of HSRTBS.展开更多
To convert wave energy into usable forms of energy by utilizing heaving body, heaving bodies （buoys） which are buoyant in nature and float on the water surface are usually used. The wave exerts excess buoyancy force...To convert wave energy into usable forms of energy by utilizing heaving body, heaving bodies （buoys） which are buoyant in nature and float on the water surface are usually used. The wave exerts excess buoyancy force on the buoy, lifting it during the approach of wave crest while the gravity pulls it down during the wave trough. A hydraulic, direct or mechanical power takeoff is used to convert this up and down motion of the buoy to produce usable forms of energy. Though using a floating buoy for harnessing wave energy is conventional, this device faces many challenges in improving the overall conversion efficiency and survivability in extreme conditions. Up to the present, no studies have been done to harness ocean waves using a non-floating object and to find out the merits and demerits of the system. In the present paper, an innovative heaving body type of wave energy converter with a non-floating object was proposed to harness waves. It was also shown that the conversion efficiency and safety of the proposed device were significantly higher than any other device proposed with floating buoy. To demonstrate the improvements, experiments were conducted with non- floating body for different dimensions and the heave response was noted. Power generation was not considered in the experiment to observe the worst case response of the heaving body. The device was modeled in artificial neural network （ANN）, the heave response for various parameters were predicted, and compared with the experimental results. It was found that the ANN model could predict the heave response with an accuracy of 99%.展开更多
Here, we present a numerical investigation of the mechanical behavior of ellipsoids under triaxial com- pression for a range of aspect ratios. Our simulations use a multi-sphere approach in a three-dimensional discret...Here, we present a numerical investigation of the mechanical behavior of ellipsoids under triaxial com- pression for a range of aspect ratios. Our simulations use a multi-sphere approach in a three-dimensional discrete element method. All assemblies were prepared at their densest condition, and triaxial compres- sion tests were performed up to extremely large strains, until a critical state was reached. The stress-strain relationship and the void ratio-strain behavior were evaluated. We found that the stress-dilatancy rela- tionship of ellipsoids with different aspect ratios could be expressed as a linear equation. In particular, the aspect ratio influenced the position of the critical state lines for these assemblies. Particle-scale char- acteristics at the critical state indicate that particles tend to be flat lying, and the obstruction of particle rotation that occurs with longer particles affects their contact mechanics. Lastly, anisotropic coefficients related to aspect ratio were investigated to probe the microscopic origins of the macroscopic behavior. A detailed analysis of geometrical and mechanical anisotropies revealed the microscopic mechanisms underlying the dependency of peak and residual strengths on aspect ratio.展开更多
文摘Implementing acoustic emission experiments with large rock samples, LURR (Load/Unload Response Ratio) theory was studied. The loading conditions in the experiments were designed to simulate the complicated loading process of underground rocks. The damages emerging inside the rock samples were recorded by the acoustic emission technique during the loading process. The experimental results were consistent with prediction by LURR theory. Integrating the changing processes of LURR value Y and the location process of acoustic emission events showed agreement between the variation of LURR value Y and the damage evolution inside the rocks. Furthermore, the high value of Y emerged before the complete breakdown of materials. Therefore, the damage evolution of rock specimen can be quantitatively analyzed with LURR theory, thus the failure of the rock materials and the earthquake occurrence may be predicted. The experimental results gave a further verification of LURR theory.
基金supported by the National Natural Science Foundation of China(No.41372297)the Natural Science Foundation of Shandong Province(No.ZR2020KE004)+1 种基金the Open Fund of Key Laboratory of Geological Safety of Coastal Urban Underground Space,Ministry of Natural Resources(No.BHKF2021Y05)the Qingdao Postdoctoral Applied Research Project and the Open Foundation of Geo-Engineering Surveying Institute of Qingdao(No.2019-QDDZYKF02).
文摘It is well known that the deformation and damage of reservoir colluvium landslides are often determined by the combined dynamics of reservoir water level change and rainfall.Based on the systematic analysis of the change law of reservoir water level,rainfall and displacements of reservoir colluvium landslide,this paper proposes the compound hydrodynamic action of rainfall and reservoir water as the unload-load parameter,and the landslide displacement as the unload-load response parameter.Based on this,a physical prediction model of the compound hydrodynamic unload-load response ratio of reservoir colluvium landslide was established,and the quantitative relationship between the compound hydrodynamic unload-load response ratio and its stability evolution was in-depth analyzed and determined.On the basis of the above research,taking Shuping landslide,a typical hydrodynamic pressure landslide as an example,the unload-load response ratio model is used to systematically evaluate and predict the stability evolution law and the change trend of the landslide under compound hydrodynamic action.The prediction result shows that the variation law of the compound hydrodynamic unload-load response ratio is consistent with the dynamic evolution law of its stability.Therefore,the above studies show that the compound hydrodynamic unload-load response ratio parameter is an effective displacement dynamic evaluation parameter for reservoir colluvium landslides,so it can be used in the prediction of the reservoir colluvium landslides.
基金Key project from China Seismological Bureau (9691309020301) State Natural Sciences Foundation of China (19732060).
文摘Rock experiment results indicate that the load/unload response ratio (LURR) of rocks expressed via strain energy may have singular or negative value after the stress in the rock reaches its maximum before rock failure or when the rock goes into the strain-weakening phase. The universality of this phenomenon is discussed. Expressed via strain or strain energy and the travel time of P wave, the variation form of the reciprocal of LURR during the process of rock failure preparation is derived. The results show that after a sharp decrease the reciprocal of LURR reaches its minimum when the main fracture of the rock is about to appear. This feature can be taken as an indication that the rock main fracture is impending.
基金State Natural Science Foundation (19732006) and Beijing Natural Science Foundation (8992008).
文摘In this paper, the tempo-spatial evolution characteristics of the load/unload response ratio (namely LURR or Y value) before strong earthquakes with magnitude over 6 during 1976~1994 in California of America are studied in detail. The results show that there appear some high-Y regions cohering with the regional tectonic trend in a great area 3~4 years before strong earthquakes and these high-Y regions migrate from the periphery to the epicenter region at a speed of tens of kilometers per year. The load/unload response ratio (LURR) anomalies near the epicenter region characterizes a type of (ascend ? descend( and appear and increase steeply until one year or less before most earthquakes. (Positive( earthquakes form usually a concentration area; in and near which the main shock occurs. We have analyzed the different and same characters of earthquakes between California of American and the Chinese mainland. Basing on these results, we discuss the approach and method how to predict and estimate the three parameters (place, time and magnitude) of a strong earthquake in California of American by applying the characteristics of the LURR.
基金This project was sponsored by the National Natural Science Foundation of China ( Grant No.10232050 , No.10572140)the State "973"Programme of China(2002CB412706)
文摘The variation of Load/Unload Response Ratio (LURR) against time for earthquakes in Kerman Province, Iran, on February 22, 2005, M6.4 and in Lorestan Province, Iran, on March 31, 2006, M6.1, has been calculated and analysed in this paper. The tempo-spatial scanning of LURR in the region of Iran during January 1, 2003 to March 31, 2006 has been conducted, with 1 year as a time-window, 1 month as a time-step, and the comparison of the LURR anomalous regions in 2004 with the actual earthquakes with M≥5.0 in the next year (2005) is also given, which shows that 11 earthquakes with M≥5.0 occurred in LURR anomalous regions while 12 earthquakes with M≥5.0 in LURR regions in 2005. Furthermore, the seismicity in this region is studied by investigating the evolvement of the anomalous LURR regions.
基金Supported by Key Projects of Anhui Provincial Department of Education,No.2023AH053330.
文摘BACKGROUND Gastric cancer(GC)has a relatively high incidence and mortality rate.Surgery is the primary treatment;however,the survival rate of patients remains low.Therefore,there is an urgent need to identify simple and feasible prognostic indicators for GC.As an inflammation-related biomarker,the systemic inflammation response index(SIRI),platelet-to-lymphocyte ratio(PLR),and SIRI-PLR can be obtained from routine blood tests.Compared with existing prognostic indicators,which are expensive and rely on complex analyses,SIRI-PLR offers extremely high convenience and cost-effectiveness.AIM To explore the impact of SIRI-PLR on the prognosis of patients with stage I–III GC after surgery and construct a nomogram.METHODS We retrospectively analyzed the clinical and pathological data of patients with GC who underwent radical surgery at The First Affiliated Hospital of Anhui Medical University between January 2014 and December 2017.A total of 1071 patients with clear clinical prognoses were selected.Univariate and multivariate Cox regression analyses were performed to identify independent prognostic factors associated with overall survival in patients with GC,and a nomogram prediction model was constructed.RESULTS Multivariate Cox regression analysis revealed that age,tumor size,T stage,N stage,SIRI-PLR,and carcinoembryonic antigen were independent prognostic factors.The areas under the curve of the nomogram for training and validation sets were 0.821 and 0.848,respectively.Calibration plots and decision curve analyses demonstrated that the nomogram exhibited good predictive performance and clinical utility in training and validation cohorts.CONCLUSION Preoperative SIRI-PLR was significantly associated with the prognosis of patients with stage I–III GC following radical gastrectomy.Our nomogram could serve as an essential tool for clinicians to predict the postoperative prognosis of patients with stage I–III GC.
文摘In this paper, through the nonlinear response of rock strain and stress, we have analized the physical mechanism of loading and unloading response ratio of the well level to the earth tides,the respouse of an aquifer of confined well to bulk strain tide and showed two methods of the calculation of loading and unloading response ratio of the well level to the earth tides. We took the example of the Yu 01 well, which is near the epicenter of Heze M S 5.9 earthquake, calculated the response rate and loading and unloading response ratio of two kinds of the earth tides of it. The response rate and response ratio before the earthquake had the variation of increase.
文摘The spatial temPOral evolution characteristics of the load/unload response ratio (Y) before strong earthquakes is studied in this paper. The results show that the regions of high value of Y migrate and converge to the impending earthquake epicenter from different directions before the occurrence of the event. Basing on this discovery, it is proposed that the method can be used to predict the three elements of an earthquake. It was applied to predict that an earthquake would occur in the western part of Yunnan Province, southwestern China. The three elements (time, space and magnitude) of the Menglian earthquake with Ms7.3 which occurred on July 12, 1995 in Yunnan Province tallied with our prediction.
基金Project(2011CB013605)supported by the National Basic Research Development Program of China(973 Program)Projects(51178071,51008041)supported by the National Natural Science Foundation of ChinaProject(NCET-12-0751)supported by the New Century Excellent Talents Program in University of Ministry of Education of China
文摘In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(V/H) were investigated using the ground motion recordings from the K-NET network and the seafloor earthquake measuring system(SEMS).The results indicate that the vertical component of offshore motions is lower than that of onshore motions.The V/H PGA ratio of acceleration time histories at offshore stations is about 50%of the ratio at onshore stations.The V/H for offshore ground motions is lower than that for onshore motions,especially for periods less than 0.8 s.Furthermore,based on the results in statistical analysis for offshore recordings in the K-NET,the simplified V/H design equations for offshore motions in minor and moderate earthquakes are proposed for seismic analysis of offshore structures.
基金Under the auspices of the National Key R&D Program of China(No.2017YFC0505906)the National Natural Science Foundation of China(No.51639001,51379012)the Interdiscipline Research Funds of Beijing Normal University
文摘Plant invasion alters the fundamental structure and function of native ecosystems by affecting the biogeochemical pools and fluxes of materials and energy. Native(Suaeda salsa) and invasive(Spartina alterniflora) salt marshes were selected to study the effects of Spartina alterniflora invasion on soil organic carbon(SOC) contents and stocks in the Yellow River Delta. Results showed that the SOC contents(g/kg) and stocks(kg/m^2) were significantly increased(P < 0.05) after Spartina alterniflora invasion of seven years, especially for the surface soil layer(0–20 cm). The SOC contents exhibited an even distribution along the soil profiles in native salt marshes, while the SOC contents were gradually decreased with depth after Spartina alterniflora invasion of seven years. The natural ln response ratios(Ln RR) were applied to identify the effects of short-term Spartina alterniflora invasion on the SOC stocks. We also found that Spartina alterniflora invasion might cause soil organic carbon losses in a short-term phase(2–4 years in this study) due to the negative Ln RR values, especially for 20–60 cm depth. And the SOCD in surface layer(0–20 cm) do not increase linearly with the invasive age. Spearman correlation analysis revealed that silt + clay content was exponentially related with SOC in surface layer(Adjusted R^2 = 0.43, P < 0.001), suggesting that soil texture could play a key role in SOC sequestration of coastal salt marshes.
文摘Load-Unload Response Ratio (LURR) is a new promising approach to earthquake prediction. In the previous years, a series of successful medium-term predictions have been made for strong earthquakes on the Chinese mainland using this method. In order to investigate whether the LURR method applies to different tectonic regimes, i.e., whether it is universal, the San Andreas Fault and its vicinities are chosen as the study region in this paper. The spatial variation of LURR in the western United States (30°～50°N, 100°～130°W) is studied in detail and the earthquake tendency in this region is discussed based on historic earthquake cases.
基金sponsored by the Special Basic Scientific Research Program of Institute of Earthquake Science(02092425),China Earthquake Administration
文摘Previous studies have shown that the active tectonic block boundaries in the Chinese mainland are the main belts and concentration areas of strong earthquakes occurring in the Chinese mainland.It is essential to carry out follow-up analysis of strong earthquake risk of active tectonic block boundaries.In this paper,we carry out the analysis on the tendency of strong earthquakes along each active tectonic block boundary from three aspects respectively,including the evolutionary characteristics of the Load/Unload Response Ratio time series,the probability method based on the log-normal distribution function,and variation of b value.The estimation of strong earthquake criticality on each active tectonic block boundary is done based on the evolutionary characteristics of the Load/Unload Response Ratio time series,the cumulative probability and conditional probability,and the decrease of the b value.Finally,according to the results of analyses on the above three aspects,the potential strong earthquake areas in the forthcoming 5 years in the Chinese mainland are discussed.
基金Natural Science and Engineering Research Council of Canada, the University of Western Ontario and the National Council of Science and Technology (CONACyT) of Mexico
文摘The existence of the principal directions of the ground motion based on Arias intensity is well-known. These principal directions do not necessarily coincide with the orientations of recording sensors or with the orientations along which the ground motion parameters such as the peak ground acceleration and the pseudo-spectral acceleration （PSA） are maximum. This is evidenced by the fact that the maximum PSA at different natural vibration periods for horizontal excitations do not correspond to the same orientation. A recent analysis carried out for California earthquake records suggests that an orientation-dependent ground motion measurement for horizontal excitations can be developed. The main objective of this study is to investigate and provide seismic ground motion measurements in the horizontal plane, including bidirectional horizontal ground motions, for Mexican interplate and inslab earthquake records. Extensive statistical analyses of PSA are conducted for the assessment. The analysis results suggest that similar to the case of California records, the average behavior of the ratio of the PSA to the maximum resulting PSA can be approximated by a quarter of an ellipse in one quadrant; and that the ratio can be considered to be independent of the value of the maximum resulting PSA, earthquake magnitude, earthquake distance and the focal depth. Sets of response ratios and attenuation relationships that can be used to represent a bidirectional horizontal ground motion measurement for Mexican interplate and inslab earthquakes were also developed.
基金supported by the National Natural Science Foundation of China (Grants No.50909066 and51179108)
文摘Vulnerability to natural disasters falls into three categories： exposure, resistance, and resilience, where resilience mainly refers to the capability of a pressure-bearing system to recover by returning to its initial state, that is, the ability to adapt to disaster pressure. Resilience is a major subject of research on disaster prevention and mitigation. This research mainly focuses on the ability of the hydraulic structure to recover from the significant impacts of typhoons. According to the load/unload response ratio theory, the degree of instability by which nonlinear systems can be identified according to the difference between load and unload responses was analyzed. This analysis was used as a basis to study the resilience of a hydraulic structure. Taking the Yangtze River embankments under the impact of Typhoon Matsa as an example, the ability of the typical sections of different types of embankments to adapt to the significant impact of the typhoon, i.e., the resilience of the hydraulic structure, is described with the help of the load/unload response ratio （L）. The results of the calculated resilience reflect the actual conditions of the structure and can be used to determine the applicability of the embankment section. The load/unload response ratio theory is one of the effective tools for calculating the resilience of hydraulic structures under the significant impacts of typhoons.
文摘This paper studies the evolution charateristics of positive and negative quakes before Hyugo earthquake of M =7.2 and several strong quakes in Kanto area in Japan.The results show that the earthquakes over a certain megnitude are mainly positive ones a certain time before the main shock in or near the focal regions of most strong quakes,and form a concentratingintervals of positive quakes,The main quakes generally locate in or near the areas of positive quake distribution.Negative quakes often occur several months before the main shocks (not excluding positive ones), with the decrease of LURR (Loading/Unloading Response Ratio) values.It possibly shows that earthquake generating process has come to a short term stage.These characteristics may help to predict the time and location of the future earthquakes,and have been applied to the preliminary prediction of the time and the location of the earthquake of M =6.6 on Sep.11,1996 in Kanto area.
基金supported by Public Utility Research Project (200808053)Research Foundation of Science and Technology Plan Project in Hebei Province (12276903D)
文摘We use the Centroid Moment Tensor （CMT） solution of the earthquakes occurred in Chile subduction to analyze the characteristics of focal mechanisms. We define the,angle between P, B, and T axes of focal mechanisms and three stress axes of tectonic stress field as the consistency parameter, to research the dynamic changes of focal mechanism pattern in earthquake preparation area before the 2010 Maule, Chile earthquake. The result shows that the consistency parameter decreases before the earthquake, and the area of the lower consistent parameter visually coincides with the distribution of aftershocks. This phenomenon is similar to the Load-Unload Response Ratio （LURR） decreases prior to the occurrence of macro-fracture happened in the acoustic emission experiments involving large rock specimens under tri-axial stress.
基金The research was funded by the National NaturalSciences Foundation of China with Grant Number :50408005 and 50578004
文摘According to the epicenter distance and the site classification, the 404 groups of earthquake recordings of the main shock of the Chi-Chi, Taiwan China earthquake in 1999 are catalogued. Based on these data, we analyze the statistical features of duration, PGA, envelopes and the response spectra ratio of the horizontal and vertical components of the acceleration recordings. The results of these analyses show that the effect of site classification on the acceleration of various components is obvious; furthermore, fault direction also has certain effects on the characteristics of the horizontal components of ground motion. The detailed research results are as follows： （ 1 ） the duration of the horizontal components of acceleration records increases with the softening of the site; （2） the direction of fault slip has some effects on PGA＇s attenuation features; （3） the average envelopes of acceleration records at different distances and site dames are basically single peak functions of time and the envelopes of horizontal and vertical components of ground motion are obviously different; （4） with the same epicenter distance, EW/NS response spectrum ratios tend to approximate 1.0 as the site becomes softer and the period shorter. V/H response spectrum ratios in short periods （〈 0. 1s） increase with the softening of site, however, V/H ratios within the long-period range （ 〉 characteristic period） decrease with the softening of the site, and the decrease of V/EW ratio speeds up relatively.
基金supported by the National Key Research and Development Program of China(No.2022YFC3004304)the National Natural Science Foundation of China(Grant No.52378209)+1 种基金the Hunan Province Science and Technology Project Huxiang Young Talents Program(No.2023RC3057)the Xiaohe SciTech Talents Special Funding under Hunan Provincial Sci-Tech Talents Sponsorship Program(No.2023TJ-X66).
文摘The high-speed railway track-bridge system(HSRTBS)is susceptible to damage under the effects of earthquakes,thus threatening the safety of running trains.To improve the seismic performance of HSRTBS and reduce damage to the system,a replaceable X-shaped Energy Dissipating Steel Damper(X-EDSD)is proposed,which contains the energy-dissipating component(EDC)to dissipate the earthquake energy.Cyclic tests were performed to obtain the hysteretic performance of the EDC and X-EDSD,and a test-validated numerical model was developed to conduct parametric analyses.The X-EDSD was simplified as a nonlinear spring element with hysteretic parameters and modeled into the numerical model of the HSRTBS for seismic dynamic analyses.The peak displacements of girder and rail decreased by approximately 48.1%and 47.7%,respectively.The peak deflections of the fasteners,cement asphalt mortar layer and sliding layer were reduced by 70.4%,70.8%,and 86.1%,respectively.A comprehensive consideration of the system response control-economic cost ratio coefficient R_(pe)is proposed,and the optimal thickness of 14.94 mm is obtained by applying cubic term coefficient fitting according to 5 groups of steel plate thickness data for the specific case study in this paper.The method can be used for cost-informed X-EDSD-selection for seismic mitigation of HSRTBS.
文摘To convert wave energy into usable forms of energy by utilizing heaving body, heaving bodies （buoys） which are buoyant in nature and float on the water surface are usually used. The wave exerts excess buoyancy force on the buoy, lifting it during the approach of wave crest while the gravity pulls it down during the wave trough. A hydraulic, direct or mechanical power takeoff is used to convert this up and down motion of the buoy to produce usable forms of energy. Though using a floating buoy for harnessing wave energy is conventional, this device faces many challenges in improving the overall conversion efficiency and survivability in extreme conditions. Up to the present, no studies have been done to harness ocean waves using a non-floating object and to find out the merits and demerits of the system. In the present paper, an innovative heaving body type of wave energy converter with a non-floating object was proposed to harness waves. It was also shown that the conversion efficiency and safety of the proposed device were significantly higher than any other device proposed with floating buoy. To demonstrate the improvements, experiments were conducted with non- floating body for different dimensions and the heave response was noted. Power generation was not considered in the experiment to observe the worst case response of the heaving body. The device was modeled in artificial neural network （ANN）, the heave response for various parameters were predicted, and compared with the experimental results. It was found that the ANN model could predict the heave response with an accuracy of 99%.
基金This research was supported by the National Natural Science Foundation of China （51479027, 51539008）.
文摘Here, we present a numerical investigation of the mechanical behavior of ellipsoids under triaxial com- pression for a range of aspect ratios. Our simulations use a multi-sphere approach in a three-dimensional discrete element method. All assemblies were prepared at their densest condition, and triaxial compres- sion tests were performed up to extremely large strains, until a critical state was reached. The stress-strain relationship and the void ratio-strain behavior were evaluated. We found that the stress-dilatancy rela- tionship of ellipsoids with different aspect ratios could be expressed as a linear equation. In particular, the aspect ratio influenced the position of the critical state lines for these assemblies. Particle-scale char- acteristics at the critical state indicate that particles tend to be flat lying, and the obstruction of particle rotation that occurs with longer particles affects their contact mechanics. Lastly, anisotropic coefficients related to aspect ratio were investigated to probe the microscopic origins of the macroscopic behavior. A detailed analysis of geometrical and mechanical anisotropies revealed the microscopic mechanisms underlying the dependency of peak and residual strengths on aspect ratio.
