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
Streamlined box girders serve as a prevalent choice for the primary structural elements in large-span suspension bridge designs.With the increase in traffic demands,the design of such girders is evolving towards wider...Streamlined box girders serve as a prevalent choice for the primary structural elements in large-span suspension bridge designs.With the increase in traffic demands,the design of such girders is evolving towards wider bridge decks and larger aspect ratios(B/D).To obtain more effective and aerodynamic design shapes for streamlined box girders,it is essential to investigate the impact of B/D on their aerodynamic performance.Accordingly,in this study we investigate the buffeting responses of large-span suspension bridges using girders of varying aspect ratios(B/D of 7.5,9.3,and 12.7).First,the aerodynamic coefficients of these girders are estimated using computational fluid dynamics(CFD)simulations.Subsequently,spatial finite element(FE)models of three long-span suspension bridges with different girders(B/D of 7.5,9.3,and 12.7)are established in Ansys software,and the dynamic characteristics of these bridges are obtained.Then,the time-domain buffeting analysis is performed by simulating the fluctuating wind fields acting on the bridge through the spectral representation method.Ultimately,the buffeting responses are computed using Ansys software,and the impact of B/D on these responses is assessed.The results reveal that the root mean square(RMS)values of the main girder’s buffeting displacement are highest at the midspan position and are lowest at the ends of the bridge.A decrease in B/D of the main girder leads to a more severe buffeting response because both the range and the effective value of the displacement increase with the decreasing B/D.Comparing the buffeting displacements in three directions,B/D plays a significant role in the vertical buffeting displacement,moderately impacts the torsional displacement,and has the least effect on the lateral displacement.The findings of this study may help wind resistance analysis and design optimization for bridges.展开更多
Flexibility of underground structures relative to the surrounding medium, referred to as the flexibility ratio, is an important factor that influences their dynamic interaction. This study investigates the flexibility...Flexibility of underground structures relative to the surrounding medium, referred to as the flexibility ratio, is an important factor that influences their dynamic interaction. This study investigates the flexibility effect of a box-shaped subway tunnel, resting directly on bedrock, on the ground surface acceleration response using a numerical model verified against dynamic centrifuge test results. A comparison of the ground surface acceleration response for tunnel models with different flexibility ratios revealed that the tunnels with different flexibility ratios influence the acceleration response at the ground surface in different ways. Tunnels with lower flexibility ratios have higher acceleration responses at short periods, whereas tunnels with higher flexibility ratios have higher acceleration responses at longer periods. The effect of the flexibility ratio on ground surface acceleration is more prominent in the high range of frequencies. Furthermore, as the flexibility ratio of the tunnel system increases, the acceleration response moves away from the free field response and shifts towards the longer periods. Therefore, the flexibility ratio of the underground tunnels influences the peak ground acceleration （PGA） at the ground surface, and may need to be considered in the seismic zonation of urban areas.展开更多
Root/shoot(R/S)ratio is an important index for assessing plant health,and has received increased attention in the last decades as a sensitive indicator of plant stress induced by chemical or physical agents.The R/S ra...Root/shoot(R/S)ratio is an important index for assessing plant health,and has received increased attention in the last decades as a sensitive indicator of plant stress induced by chemical or physical agents.The R/S ratio has been discussed in the context of ecological theory and its potential importance in ecological succession,where species follow different strategies for above-ground growth for light or below-ground competition for water and nutrients.We present evidence showing the R/S ratio follows a biphasic dose–response relationship under stress,typical of hormesis.The R/S ratio in response to stress has been widely compared among species and ecological succession classes.It is constrained by a variety of factors such as ontogeny.Furthermore,the current literature lacks dose-response studies incorporating the full dose–response continuum,hence limiting scientific understanding and possible valuable application.The data presented provide an important perspective for new-generation studies that can advance current ecological understanding and improve carbon storage estimates by R/S ratio considerations.Hormetic response of the R/S ratio can have an important role in forestry for producing seedlings with desired characteristics to achieve maximum health/productivity and resilience under plantation conditions.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
This article deals with the investigation of the effects of porosity distributions on nonlinear free vibration and transient analysis of porous functionally graded skew(PFGS)plates.The effective material properties of...This article deals with the investigation of the effects of porosity distributions on nonlinear free vibration and transient analysis of porous functionally graded skew(PFGS)plates.The effective material properties of the PFGS plates are obtained from the modified power-law equations in which gradation varies through the thickness of the PFGS plate.A nonlinear finite element(FE)formulation for the overall PFGS plate is derived by adopting first-order shear deformation theory(FSDT)in conjunction with von Karman’s nonlinear strain displacement relations.The governing equations of the PFGS plate are derived using the principle of virtual work.The direct iterative method and Newmark’s integration technique are espoused to solve nonlinear mathematical relations.The influences of the porosity distributions and porosity parameter indices on the nonlinear frequency responses of the PFGS plate for different skew angles are studied in various parameters.The effects of volume fraction grading index and skew angle on the plate’s nonlinear dynamic responses for various porosity distributions are illustrated in detail.展开更多
Bed morphology is the result of a dynamic response to a complex meandering river system. It is an important factor for the further development of river. Based on the meandering river characterized by a large depth-to-...Bed morphology is the result of a dynamic response to a complex meandering river system. It is an important factor for the further development of river. Based on the meandering river characterized by a large depth-to-width ratio, a theoretical model is established with the coupling of Navier-Stokes （N-S）~ sediment transport, and bed deformation equations. The flow characteristics and bed response of river are obtained with the perturbation method. The research results show that, under the effect of two- dimensional flow disturbance, the bars and pools present the regular response. For a given sinuousness, the amplitude of the bed response can be used as a criterion to judge the bedform stability. The effects of the Reynolds number, disturbance wavenumber, sinuousness, and bed morphology gradient on the bed response development are described.展开更多
Aluminium alloy wheels are increasingly popular for their light weight and good thermal conductivity. Cooling Holes (CH) are introduced to reduce their weight without compromising structural integrity. Literature is s...Aluminium alloy wheels are increasingly popular for their light weight and good thermal conductivity. Cooling Holes (CH) are introduced to reduce their weight without compromising structural integrity. Literature is sparse on the effect of aspect ratio (AR) of CHs on wheels. This, work, therefore, attempts to undertake a parametric study of the effect of aspect ratio (AR) on the mechanical response of an aluminium alloy wheel with triangular, quadrilateral and oval-shaped CHs. Three-dimensional wheel models (6JX14H2ET42) with triangular, quadrilateral and oval shaped CH (each with CH area of 2229 mm<sup>2</sup>) were generated, discretized, and analyzed by FEM using Creo Elements/Pro 5.0 to determine the mechanical response at the inboard bead seat at different ARs of 1, 0.5, 0.33 and 0.25, each for quadrilateral-CH and oval-CH, at a static Radial Load of 4750 N and Inflation Pressures of 0.3 and 0.15 MPa, respectively. The study shows that the magnitude of stress and displacement is affected by shape and AR of CH. From the results, it could be established that oval-shaped-CH wheel at AR of 0.5 offers greater prospect in wheel design as it was least stressed and deformed and, that the CH combination with highest integrity was the oval-CH and quadrilateral-CH at AR of 0.5.展开更多
The load/unload experiments on rock failure under pressure have been carried out in Material Test System (MTS) in the Laboratory for Non-linear Mechanics of Continuous Media (LNM), Institute of Mechanics, Chinese Acad...The load/unload experiments on rock failure under pressure have been carried out in Material Test System (MTS) in the Laboratory for Non-linear Mechanics of Continuous Media (LNM), Institute of Mechanics, Chinese Academy of Sciences, and load/unload response ratio (LURR) values with strain as response (i.e. inverse elastic constant as response rate) have been obtained. The experimental results are in accordance with theoretical results and those in real earthquakes: LURR rises just before rock failure. So LURR can be used as the precursor of rock failure and earthquake prediction.展开更多
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
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
This work introduces the branching ratio(BR) method for determining relative spectral responses,which are needed routinely in laser induced breakdown spectroscopy(LIBS). Neutral and singly ionized Ti lines in the 250...This work introduces the branching ratio(BR) method for determining relative spectral responses,which are needed routinely in laser induced breakdown spectroscopy(LIBS). Neutral and singly ionized Ti lines in the 250–498 nm spectral range are investigated by measuring laser-induced micro plasma near a Ti plate and used to calculate the relative spectral response of an entire LIBS detection system. The results are compared with those of the conventional relative spectral response calibration method using a tungsten halogen lamp, and certain lines available for the BR method are selected. The study supports the common manner of using BRs to calibrate the detection system in LIBS setups.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 effect of the mass ratio on the flow-induced vibration （FIV） of a flexible circular cylinder is experimentally investigated in a towing tank. A Tygon tube with outer and inner diameters of 7.9 mm and 4.8 mm, res...The effect of the mass ratio on the flow-induced vibration （FIV） of a flexible circular cylinder is experimentally investigated in a towing tank. A Tygon tube with outer and inner diameters of 7.9 mm and 4.8 mm, respectively, was employed for the study. The tube was connected to a carriage and towed from rest to a steady speed up to 1.6 m/s before slowing down to rest again over a distance of 1.6 m in still water. Reynolds number based on the cylinder＇s outer diameter was 800-13,000, and the reduced velocity （velocity normalized by the cylinder＇s natural frequency and outer diameter） spanned from 2 to 25. When connected, the cylinder was elongated from 420 mm to 460 mm under an axial pre-tension of 11 N. Based on the cylinder＇s elongated length, the aspect ratio （ratio of the cylinder＇s length to outer diameter） was calculated as 58. Three mass ratios （ratio of the cylinder＇s structural mass to displaced fluid mass, m＊） of 0.7, 1.0, and 3.4 were determined by filling the cylinder＇s interior with air, water, and alloy powder （nickel-chromium-boron matrix alloy）, respectively. An optical method was adopted for response measurements. Multi-frequency vibrations were observed in both in-line （IL） and cross-flow （CF） responses; at high Reynolds number, vibration modes up to the 3rd one were identified in the CF response. The mode transition was found to occur at a lower reduced velocity for the highest tested mass ratio. The vibration amplitude and frequency were quantified and expressed with respect to the reduced velocity. A significant reduced vibration amplitude was found in the IL response with increasing mass ratios, and only initial and upper branches existed in the IL and CF response amplitudes. The normalized response frequencies were revealed to linearly increase with respect to the reduced velocity, and slopes for linear relations were found to be identical for the three cases tested.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
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
The load/unload response ratio YQ with the geophysical parameter coda Q-1 of the crust as response is denned in this study.The variation in YQ-1 before and after the Northridge earthquake of January 17,1994(California...The load/unload response ratio YQ with the geophysical parameter coda Q-1 of the crust as response is denned in this study.The variation in YQ-1 before and after the Northridge earthquake of January 17,1994(California)has been investigated by using the data of coda Q-1 with frequencies of 1.5,3.0,6.0,12.0,and 24.0 Hz in the Southern California from 1987 to 1994.It can be found that YQ-1 for coda waves with all frequencies,the frequency of 12.0 Hz excluded,ascended to a certain extent prior to the occurrence of the rnainshock and returned to normality after the main shock.展开更多
In this paper,the Gutenberg-Richter model is used to generate seismic events.The events that satisfy the random distribution are also generated.With those events,the natural probability distribution of Load and Unload...In this paper,the Gutenberg-Richter model is used to generate seismic events.The events that satisfy the random distribution are also generated.With those events,the natural probability distribution of Load and Unload Response Ratio(LURR),which measures quantitatively the degree of instability of a nonlinear system,is discussed.The study is based on stress energy release,which is chosen as the response of nonlinear system F3.The comparative results from the observation catalogue and generating data are also studied.It is revealed that the natural probability of LURR is mostly stable when the sample number is sufficient.The lower the natural probability of LURR,the more the precursory is information it may contain.The influence of Y3 resulting from the sample number and the magnitude range of events is also discussed.展开更多
The variation in load/unload response ratio before some moderate earthquakes is analyzed based on the theory of the load/unload response ratio.The results show that the load-unload response ratio increases noticeably ...The variation in load/unload response ratio before some moderate earthquakes is analyzed based on the theory of the load/unload response ratio.The results show that the load-unload response ratio increases noticeably before moderate earthquakes,and there are three kinds of patterns in which the load/unload response ratio varies and the duration of noticeable increase in load/unload response ratio ranges from half a year to two years.展开更多
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.
基金funded by the National Natural Science Foundation of China(Grant No.52108435)the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJQN202404320)+1 种基金Chongqing Jiaotong University Postgraduate Research and Innovation Project(2024S0013)Chongqing Jiaotong University Undergraduate Innovation and Entrepreneurship Project(S202410618019).
文摘Streamlined box girders serve as a prevalent choice for the primary structural elements in large-span suspension bridge designs.With the increase in traffic demands,the design of such girders is evolving towards wider bridge decks and larger aspect ratios(B/D).To obtain more effective and aerodynamic design shapes for streamlined box girders,it is essential to investigate the impact of B/D on their aerodynamic performance.Accordingly,in this study we investigate the buffeting responses of large-span suspension bridges using girders of varying aspect ratios(B/D of 7.5,9.3,and 12.7).First,the aerodynamic coefficients of these girders are estimated using computational fluid dynamics(CFD)simulations.Subsequently,spatial finite element(FE)models of three long-span suspension bridges with different girders(B/D of 7.5,9.3,and 12.7)are established in Ansys software,and the dynamic characteristics of these bridges are obtained.Then,the time-domain buffeting analysis is performed by simulating the fluctuating wind fields acting on the bridge through the spectral representation method.Ultimately,the buffeting responses are computed using Ansys software,and the impact of B/D on these responses is assessed.The results reveal that the root mean square(RMS)values of the main girder’s buffeting displacement are highest at the midspan position and are lowest at the ends of the bridge.A decrease in B/D of the main girder leads to a more severe buffeting response because both the range and the effective value of the displacement increase with the decreasing B/D.Comparing the buffeting displacements in three directions,B/D plays a significant role in the vertical buffeting displacement,moderately impacts the torsional displacement,and has the least effect on the lateral displacement.The findings of this study may help wind resistance analysis and design optimization for bridges.
文摘Flexibility of underground structures relative to the surrounding medium, referred to as the flexibility ratio, is an important factor that influences their dynamic interaction. This study investigates the flexibility effect of a box-shaped subway tunnel, resting directly on bedrock, on the ground surface acceleration response using a numerical model verified against dynamic centrifuge test results. A comparison of the ground surface acceleration response for tunnel models with different flexibility ratios revealed that the tunnels with different flexibility ratios influence the acceleration response at the ground surface in different ways. Tunnels with lower flexibility ratios have higher acceleration responses at short periods, whereas tunnels with higher flexibility ratios have higher acceleration responses at longer periods. The effect of the flexibility ratio on ground surface acceleration is more prominent in the high range of frequencies. Furthermore, as the flexibility ratio of the tunnel system increases, the acceleration response moves away from the free field response and shifts towards the longer periods. Therefore, the flexibility ratio of the underground tunnels influences the peak ground acceleration （PGA） at the ground surface, and may need to be considered in the seismic zonation of urban areas.
基金supported by JSPS KAKENHI Grant Number JP17F17102German Research Foundation(BE4189/1-3)+1 种基金the US Air Force[AFOSR FA9550-13-1-0047]Exxon Mobil Foundation[S18200000000256]
文摘Root/shoot(R/S)ratio is an important index for assessing plant health,and has received increased attention in the last decades as a sensitive indicator of plant stress induced by chemical or physical agents.The R/S ratio has been discussed in the context of ecological theory and its potential importance in ecological succession,where species follow different strategies for above-ground growth for light or below-ground competition for water and nutrients.We present evidence showing the R/S ratio follows a biphasic dose–response relationship under stress,typical of hormesis.The R/S ratio in response to stress has been widely compared among species and ecological succession classes.It is constrained by a variety of factors such as ontogeny.Furthermore,the current literature lacks dose-response studies incorporating the full dose–response continuum,hence limiting scientific understanding and possible valuable application.The data presented provide an important perspective for new-generation studies that can advance current ecological understanding and improve carbon storage estimates by R/S ratio considerations.Hormetic response of the R/S ratio can have an important role in forestry for producing seedlings with desired characteristics to achieve maximum health/productivity and resilience under plantation conditions.
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.
文摘This article deals with the investigation of the effects of porosity distributions on nonlinear free vibration and transient analysis of porous functionally graded skew(PFGS)plates.The effective material properties of the PFGS plates are obtained from the modified power-law equations in which gradation varies through the thickness of the PFGS plate.A nonlinear finite element(FE)formulation for the overall PFGS plate is derived by adopting first-order shear deformation theory(FSDT)in conjunction with von Karman’s nonlinear strain displacement relations.The governing equations of the PFGS plate are derived using the principle of virtual work.The direct iterative method and Newmark’s integration technique are espoused to solve nonlinear mathematical relations.The influences of the porosity distributions and porosity parameter indices on the nonlinear frequency responses of the PFGS plate for different skew angles are studied in various parameters.The effects of volume fraction grading index and skew angle on the plate’s nonlinear dynamic responses for various porosity distributions are illustrated in detail.
文摘Bed morphology is the result of a dynamic response to a complex meandering river system. It is an important factor for the further development of river. Based on the meandering river characterized by a large depth-to-width ratio, a theoretical model is established with the coupling of Navier-Stokes （N-S）~ sediment transport, and bed deformation equations. The flow characteristics and bed response of river are obtained with the perturbation method. The research results show that, under the effect of two- dimensional flow disturbance, the bars and pools present the regular response. For a given sinuousness, the amplitude of the bed response can be used as a criterion to judge the bedform stability. The effects of the Reynolds number, disturbance wavenumber, sinuousness, and bed morphology gradient on the bed response development are described.
文摘Aluminium alloy wheels are increasingly popular for their light weight and good thermal conductivity. Cooling Holes (CH) are introduced to reduce their weight without compromising structural integrity. Literature is sparse on the effect of aspect ratio (AR) of CHs on wheels. This, work, therefore, attempts to undertake a parametric study of the effect of aspect ratio (AR) on the mechanical response of an aluminium alloy wheel with triangular, quadrilateral and oval-shaped CHs. Three-dimensional wheel models (6JX14H2ET42) with triangular, quadrilateral and oval shaped CH (each with CH area of 2229 mm<sup>2</sup>) were generated, discretized, and analyzed by FEM using Creo Elements/Pro 5.0 to determine the mechanical response at the inboard bead seat at different ARs of 1, 0.5, 0.33 and 0.25, each for quadrilateral-CH and oval-CH, at a static Radial Load of 4750 N and Inflation Pressures of 0.3 and 0.15 MPa, respectively. The study shows that the magnitude of stress and displacement is affected by shape and AR of CH. From the results, it could be established that oval-shaped-CH wheel at AR of 0.5 offers greater prospect in wheel design as it was least stressed and deformed and, that the CH combination with highest integrity was the oval-CH and quadrilateral-CH at AR of 0.5.
基金This project was sponsored by the National Natural Science Foundation (No. 19732006), China and Ninth Five-year Plan, China Seismological Bureau.
文摘The load/unload experiments on rock failure under pressure have been carried out in Material Test System (MTS) in the Laboratory for Non-linear Mechanics of Continuous Media (LNM), Institute of Mechanics, Chinese Academy of Sciences, and load/unload response ratio (LURR) values with strain as response (i.e. inverse elastic constant as response rate) have been obtained. The experimental results are in accordance with theoretical results and those in real earthquakes: LURR rises just before rock failure. So LURR can be used as the precursor of rock failure and earthquake prediction.
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.
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.
基金supported by the National Key Scientific Instrument and Equipment Development Projects of China (2014YQ120351)National Natural Science Foundation of China (11704372)Anhui Provincial Natural Science Foundation (1708085QF130)
文摘This work introduces the branching ratio(BR) method for determining relative spectral responses,which are needed routinely in laser induced breakdown spectroscopy(LIBS). Neutral and singly ionized Ti lines in the 250–498 nm spectral range are investigated by measuring laser-induced micro plasma near a Ti plate and used to calculate the relative spectral response of an entire LIBS detection system. The results are compared with those of the conventional relative spectral response calibration method using a tungsten halogen lamp, and certain lines available for the BR method are selected. The study supports the common manner of using BRs to calibrate the detection system in LIBS setups.
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.
文摘The effect of the mass ratio on the flow-induced vibration （FIV） of a flexible circular cylinder is experimentally investigated in a towing tank. A Tygon tube with outer and inner diameters of 7.9 mm and 4.8 mm, respectively, was employed for the study. The tube was connected to a carriage and towed from rest to a steady speed up to 1.6 m/s before slowing down to rest again over a distance of 1.6 m in still water. Reynolds number based on the cylinder＇s outer diameter was 800-13,000, and the reduced velocity （velocity normalized by the cylinder＇s natural frequency and outer diameter） spanned from 2 to 25. When connected, the cylinder was elongated from 420 mm to 460 mm under an axial pre-tension of 11 N. Based on the cylinder＇s elongated length, the aspect ratio （ratio of the cylinder＇s length to outer diameter） was calculated as 58. Three mass ratios （ratio of the cylinder＇s structural mass to displaced fluid mass, m＊） of 0.7, 1.0, and 3.4 were determined by filling the cylinder＇s interior with air, water, and alloy powder （nickel-chromium-boron matrix alloy）, respectively. An optical method was adopted for response measurements. Multi-frequency vibrations were observed in both in-line （IL） and cross-flow （CF） responses; at high Reynolds number, vibration modes up to the 3rd one were identified in the CF response. The mode transition was found to occur at a lower reduced velocity for the highest tested mass ratio. The vibration amplitude and frequency were quantified and expressed with respect to the reduced velocity. A significant reduced vibration amplitude was found in the IL response with increasing mass ratios, and only initial and upper branches existed in the IL and CF response amplitudes. The normalized response frequencies were revealed to linearly increase with respect to the reduced velocity, and slopes for linear relations were found to be identical for the three cases tested.
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This project was sponsored by the National Natural Science Foundation, China
文摘The load/unload response ratio YQ with the geophysical parameter coda Q-1 of the crust as response is denned in this study.The variation in YQ-1 before and after the Northridge earthquake of January 17,1994(California)has been investigated by using the data of coda Q-1 with frequencies of 1.5,3.0,6.0,12.0,and 24.0 Hz in the Southern California from 1987 to 1994.It can be found that YQ-1 for coda waves with all frequencies,the frequency of 12.0 Hz excluded,ascended to a certain extent prior to the occurrence of the rnainshock and returned to normality after the main shock.
基金This project was sponsored by the State Seismological Bureau (85-04-05-04-05)
文摘In this paper,the Gutenberg-Richter model is used to generate seismic events.The events that satisfy the random distribution are also generated.With those events,the natural probability distribution of Load and Unload Response Ratio(LURR),which measures quantitatively the degree of instability of a nonlinear system,is discussed.The study is based on stress energy release,which is chosen as the response of nonlinear system F3.The comparative results from the observation catalogue and generating data are also studied.It is revealed that the natural probability of LURR is mostly stable when the sample number is sufficient.The lower the natural probability of LURR,the more the precursory is information it may contain.The influence of Y3 resulting from the sample number and the magnitude range of events is also discussed.
文摘The variation in load/unload response ratio before some moderate earthquakes is analyzed based on the theory of the load/unload response ratio.The results show that the load-unload response ratio increases noticeably before moderate earthquakes,and there are three kinds of patterns in which the load/unload response ratio varies and the duration of noticeable increase in load/unload response ratio ranges from half a year to two years.
