Landslides are one of the most dangerous natural hazards that cause significant property damage and loss of life.Landslides often destroy farmland,villages,houses,factories,schools,roads and other facilities,injuring ...Landslides are one of the most dangerous natural hazards that cause significant property damage and loss of life.Landslides often destroy farmland,villages,houses,factories,schools,roads and other facilities,injuring humans and livestock.Sometimes,entire towns are devastated by landslides.Due to their pervasiveness,varied triggering factors,and sudden occurrence,landslides are currently one of the most challenging natural disasters to prevent and mitigate.展开更多
BACKGROUND Elevated levels of cardiac troponin and abnormal electrocardiogram changes are the primary basis for clinical diagnosis of acute coronary syndrome(ACS).Troponin levels in ACS patients can often be more than...BACKGROUND Elevated levels of cardiac troponin and abnormal electrocardiogram changes are the primary basis for clinical diagnosis of acute coronary syndrome(ACS).Troponin levels in ACS patients can often be more than 50 times the upper reference limit.Some patients with subarachnoid hemorrhage(SAH)also show electrocardiogram abnormalities,myocardial damage,and elevated cardiac biomarkers.Unlike ACS patients,patients with SAH only have a slight increase in troponin,and the use of anticoagulants or antiplatelet drugs is prohibited.Because of the opposite treatment modalities,it is essential for clinicians to distinguish between SAH and ACS.CASE SUMMARY A 56-year-old female patient was admitted to the emergency department at night with a sudden onset of severe back pain.The final diagnosis was intraspinal hematoma in the thoracic spine.We performed an emergency thoracic spinal canal hematoma evacuation procedure with the assistance of a microscope.Intraoperatively,diffuse hematoma formation was found in the T7-T10 spinal canal,and no obvious spinal vascular malformation changes were observed.Postoperative head and spinal magnetic resonance imaging(MRI)showed a small amount of SAH in the skull,no obvious abnormalities in the cervical and thoracic spinal canals,and no abnormal signals in the lumbar spinal canal.Thoracoab-dominal aorta computed tomography angiography showed no vascular malfor-mation.Postoperative motor system examination showed Medical Research Council Scale grade 1/5 strength in both lower extremities,and the patient experienced decreased sensation below the T12 rib margin and reported a Visual Analog Scale score of 3.CONCLUSION Extremely elevated troponin levels(more than 50 times the normal range)are not unique to coronary artery disease.SAH can also result in extremely high troponin levels,and antiplatelet drugs are contraindicated in such cases.Emergency MRI can help in the early differential diagnosis,as a misdiagnosis of ACS can lead to catastrophic neurological damage in patients with spontaneous spinal SAH.展开更多
Increasing population density and development of mountainous terrain have brought human settlements within reach of landslide hazards.In recent years,due to the shortening of return period for severe natural events su...Increasing population density and development of mountainous terrain have brought human settlements within reach of landslide hazards.In recent years,due to the shortening of return period for severe natural events such as heavy rainfall,snowline retreating,great earthquake together with human activities,catastrophic landslides happened more frequently than before,resulting in large-scale casualties due to the increasing occurrences of rapid long-runout rock avalanches,especially in China.This paper presents some typical case histories related to the catastrophic landslides,including the Guanling rock avalanche,the Yigong rockslide-debris avalanche,the Wenchuan earthquake-induced landslides and the Danba landslide.They occurred in the last decade.Moreover,taking the Jiweishan catastrophic rockslide-fragment flow and the Yuhuangge landslide located in the new Wushan Town for examples,early-warning system and risk management on landslides are discussed in detail.展开更多
Coal mine belt fire develops very rapidly and is difficult to control. If not suppressed quickly, a belt fire could easily lead to airflow disorder and undermine the ventilation system. However, belt fire can be preve...Coal mine belt fire develops very rapidly and is difficult to control. If not suppressed quickly, a belt fire could easily lead to airflow disorder and undermine the ventilation system. However, belt fire can be prevented effectively by establishing fire airflow control system. In this work, the 5th belt roadway of Kongzhuang coal mine was taken as the object of investigation, where geometrical models of this roadway were established firstly. Then, based on mathematical model of fire smoke flow, the CO volume fraction, smoke density distribution, air temperature and pollutant velocity vector in the roadway before and after taking airflow control measures were simulated by using Fluent software. It can be known from the simulation that with the normal ventilation status in 5th belt roadway, the countercurrent of smoke does not happen when a fire occurs; the roadway's section is almost filled with CO at 10 m downstream from the fire source, and with air velocity getting stable gradually, the CO concentration reaches about 15 %. After taking airflow control measures, the effect range of temperature field which are harmful to the miners decreases from 69 m to 30 m; and the distance of the roadway fully filled with CO is 5 m farther than that before taking measures. Finally, according to the numerical simulation results and the actual condition of the belt roadway, the warning and automatic remote airflow control system with short-circuit method for the 5th belt roadway was designed to guarantee the safety production.展开更多
This paper presents a method for analysis of stress and strain of gas pipelines under the effect of horizontal catastrophic landslides. A soil spring model was used to analyze the nonlinear characteristics concerning ...This paper presents a method for analysis of stress and strain of gas pipelines under the effect of horizontal catastrophic landslides. A soil spring model was used to analyze the nonlinear characteristics concerning the mutual effects between the pipeline and the soil. The Ramberg–Osgood model was used to describe the constitutive relations of pipeline materials. This paper also constructed a finite element analysis model using ABAQUS finite element software and studied the distribution of the maximum stress and strain of the pipeline and the axial stress and strain along the pipeline by referencing some typical accident cases. The calculation results indicated that the maximum stress and strain increased gradually with the displacement of landslide.The limit values of pipeline axial stress strain appeared at the junction of the landslide area and non-landslide area. The stress failure criterion was relatively more conservative than the strain failure criterion. The research results of this paper may be used as a technical reference concerning the design and safety management of large-diameter gas pipelines under the effects of catastrophic landslides.展开更多
To reveal the damage characteristics and catastrophic failure mechanism of coal rock caused by gas adsorption,physical tests and theoretical methods are employed.The results show that adsorption swelling can damage co...To reveal the damage characteristics and catastrophic failure mechanism of coal rock caused by gas adsorption,physical tests and theoretical methods are employed.The results show that adsorption swelling can damage coal rock,which can be distinguished by fractal dimension.A fitting relationship between the adsorption damage and fractal dimension is proposed by experimental testing and theoretical analysis.High gas adsorption pressure proves to be the dominant factor that leads to coal failure softening and gas outburst disasters.Three main parameters concerning adsorption damage include the change rate of released energy density,the transition difference in the post-peak acoustic emission(AE)b value and the change rate of cumulative AE energy.Results show that all the three parameters present a step-type decreasing change with the increase in fractal dimension,and the fractal dimension shows a linear relationship within the same failure mode.Finally,a method is proposed to evaluate coal rock disaster transformation,based on the aforementioned three main parameters of adsorption damage.展开更多
Abstract： The mathematical model of a high-speed underwater vehicle getting catastrophe in the out-of-water course and a nonlinear sliding mode control with the adaptive backstepping approach for the catastrophic cou...Abstract： The mathematical model of a high-speed underwater vehicle getting catastrophe in the out-of-water course and a nonlinear sliding mode control with the adaptive backstepping approach for the catastrophic course are proposed. The speed change is large at the moment that the high-speed underwater vehicle launches out of the water to attack an air target. It causes motion parameter uncertainties and affects the precision attack ability. The trajectory angle dynamic characteristic is based on the description of the transformed state-coordinates, the nonlinear sliding mode control is designed to track a linear reference model. Furthermore, the adaptive backstepping control approach is utilized to improve the robustness against the unknown parameter uncertainties. With the proposed control of attitude tracking, the controlled navigational control system possesses the advantages of good transient performance and robustness to parametric uncertainties. These can be predicted and regulated through the design of a linear reference model that has the desired dynamic behavior for the trajectory of the high-speed underwater vehicle to attack its target. Finally, some digital simulation results show that the control system can be applied to a catastrophic course, and that it illustrates great robustness against system parameter uncertainties and external disturbances.展开更多
The catastrophic rockslide,which frequently triggers numerous severe disasters worldwide,has drawn much attention globally;however,understanding the initiation mechanism of catastrophic rockslides in the absence of ty...The catastrophic rockslide,which frequently triggers numerous severe disasters worldwide,has drawn much attention globally;however,understanding the initiation mechanism of catastrophic rockslides in the absence of typical single triggering factors related to strong seismic activity or torrential precipitation continues to be challenging within the global scientific community.This study aims to determine the mechanism of the three largest catastrophic rockslides in the eastern Tibetan Plateau,Yigong,Xinmo,and Baige,over the past 20 years using field investigation,remote sensing,and runoff analysis.Instead of the conventional driving factors of heavy rainfall and strong earthquakes,the multi-wing butterfly effects(MWBE)of climatic factors and weak earthquakes are for the first time identified as drivers of the catastrophic rockslide disasters.First,strong tectonic uplift,fast fluvial incision,high-density faults,and large regional water confluence formed the slopes in the critical regime,creating the source conditions of rockslide.Second,the MWBE of early dry-heat events and antecedent rainfall,combined with imminent weak earthquakes,initiated rockslide.Third,the delayed amplified runoff moving toward the sliding surface and lowering the strength of the locking-rock segment constituted the fundamental mechanism of the MWBE on rockslide.The catastrophic rockslide was ultimately inferred to be a nonlinear chaotic process;however,prediction and forecasting of rockslide based on the MWBE in the early stages are possible and essential.This finding presents a new perspective concerning forecasting progressive landslides.展开更多
In order to study the mechanism of water inrush from a concealed, confined karst cave, we established a fluid–solid coupling model of water inrush from a concealed karst cave ahead of a roadway and a strength reducti...In order to study the mechanism of water inrush from a concealed, confined karst cave, we established a fluid–solid coupling model of water inrush from a concealed karst cave ahead of a roadway and a strength reduction method in a rock pillar for preventing water inrush based on catastrophic theory. Fluid–solid coupling effects and safety margins in a rock pillar were studied. Analysis shows that rock pillar instability, exerted by disturbance stress and seepage stress, is the process of rock pillar catastrophic destabilization induced by nonlinear extension of plastic zones in the rock pillar. Seepage flow emerges in the rock pillar for preventing water inrush, accompanied by mechanical instability of the rock pillar. Taking the accident of a confined karst cave water-inrush of Qiyi Mine as an example, by studying the safety factor of the rock pillar and the relationship between karst cave water pressure and thickness of the rock pillar,it is proposed that rock pillar thickness with a safety factor equal to 1.5 is regarded as the calculated safety thickness of the rock pillar, which should be equal to the sum of the blasthole depth, blasting disturbance depth and the calculated safety thickness of the rock pillar. The cause of the karst water inrush at Qiyi Mine is that the rock pillar was so small that it did not possess a safety margin. Combining fluid–solid coupling theory, catastrophic theory and strength reduction method to study the nonlinear mechanical response of complicated rock engineering, new avenues for quantitative analysis of rock engineering stability evaluation should be forthcoming.展开更多
This paper considers the effects of damage softening and hydraulic softening on fault zone media and provides a nonlinear mechanics model of fault earthquake. Taking far field displacement,stiffness ratio and permeati...This paper considers the effects of damage softening and hydraulic softening on fault zone media and provides a nonlinear mechanics model of fault earthquake. Taking far field displacement,stiffness ratio and permeation parameter as control variables, we obtain a swallowtail type catastrophic model of earthquakes. Then, by this model, we study the effects of permeation, far field displacement and stiffness ratio on the preparation and the occurrence of earthquakes.展开更多
Deep-seated catastrophic landslides,particularly rock or debris avalanches,travel extremely rapidly for long distances,causing severe damage over wide areas.This paper summarizes the geological and geomorphological fe...Deep-seated catastrophic landslides,particularly rock or debris avalanches,travel extremely rapidly for long distances,causing severe damage over wide areas.This paper summarizes the geological and geomorphological features of such events,which were induced by earthquakes and rainstorms in Asia,and then uses these features to predict future potential sites of failures.Most of the rock avalanches are preceded by gravitational slope deformation with topographic features,in which small scarps along future head of landslide are the most representative;the scarps can be identified in topographic images made by highresolution airborne LiDAR DEMs and may suggest the instability just before catastrophic failure.展开更多
A brief review of the former studies on the mechanisms of soil rheology and microstructure is presented. Then a microstructure model and a set of rheological constitutive relations for sott clays, which describe how t...A brief review of the former studies on the mechanisms of soil rheology and microstructure is presented. Then a microstructure model and a set of rheological constitutive relations for sott clays, which describe how the rheological consolidation settlement develops, are established in the framework of the catastrophe theory. The validity of this model is verified by a series of rheological consolidation experiments with different loading rates. The experimental data show that creep deformation can be clearly observed in these tests, and the consolidation settlement is loading rate dependent. The characteristics of the deformation can be explained and reproduced successfully using the model. It can be concluded that only the biggest set of voids would collapse for one load increment. Parameters in the model, k and η, are gained by curve fitting. With only two free parameters, good fits of the data are achieved.展开更多
The nonlinear and transient vibration of a rotor, which dropped onto back-up bearings when its active magnetic bearings were out of order, was investigated. After strictly deriving its equations of motion and performi...The nonlinear and transient vibration of a rotor, which dropped onto back-up bearings when its active magnetic bearings were out of order, was investigated. After strictly deriving its equations of motion and performing numerical simulations, the time-histories of rotating speed of the dropping rotor, and normal force at the rubbing contact point as well as the frequency spectrum of the vibration displacement of back-up bearings are fully analyzed. It is found that the strong and unsteady forced bending vibration of the unbalanced and, damped rotor decelerating through : its first. bending vibtation of the unbalanced and, damped rotor decelerating through its,first critical speed as well as chattering at high frequencies caused by the nonlinearity at the rubbing contact point between, the journal and back-up bearings may lead to the catastrophic damage. of the system.展开更多
In recent years,the conditions of continuous warm winter,more rain and high humidity are very beneficial to the breeding and survival of sugarcane diseases and pests.Coupled with the degradation of single varieties,mo...In recent years,the conditions of continuous warm winter,more rain and high humidity are very beneficial to the breeding and survival of sugarcane diseases and pests.Coupled with the degradation of single varieties,more attention on new plants and less on ratoon cane and the unscientific and unreasonable use of chemical pesticides,the types of sugarcane diseases and pests in the Menglian sugarcane area are increasing day by day,and the damage is increasing year by year,resulting in a substantial reduction in production and sugar,and a serious disaster threat to sugarcane production.Based on the field survey and the current sugarcane production practice in Menglian,this paper systematically reviewed the occurrence and damage dynamics and outbreak reasons of catastrophic diseases and pests that seriously influence sugarcane production,and proposed corresponding prevention and control strategies and integrated prevention and control technology according to the occurrence and damage characteristics of catastrophic diseases and pests.展开更多
<div style="text-align:justify;"> <b><span style="font-family:Verdana;">Background:</span></b><span style="font-family:Verdana;"></span><b>...<div style="text-align:justify;"> <b><span style="font-family:Verdana;">Background:</span></b><span style="font-family:Verdana;"></span><b> </b><span style="font-family:Verdana;">The interplay between financial deprivation and tuberculosis (TB) is considered one of the vital socio-economic determinants of disease. This is the first study of its kind to be carried in Pakistan, which aims to identify leading factors contributing towards catastrophic costs of TB diagnosis and management in order to help policy makers. <b></b></span><b><b><span style="font-family:Verdana;">Methodology:</span></b><span style="font-family:Verdana;"></span></b><b> </b><span style="font-family:Verdana;">From </span><span style="font-family:Verdana;">f</span><span style="font-family:Verdana;">our tertiary care hospitals (TCH) in Islamabad and Rawalpindi</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> 400 TB patients were interviewed through a cross-sectional survey. The patient’s pre and post</span><span style="font-family:Verdana;">-</span><span "=""><span style="font-family:Verdana;">TB income and direct and indirect costs for treatment were analysed following WHO recommendations. Multivariable logistic regression model was used to identify the determinants of catastrophic total cost. <b></b></span><b><b><span style="font-family:Verdana;">Results:</span></b><span style="font-family:Verdana;"><b></b></span><b><b> </b></b></b><span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span><span style="font-family:Verdana;">For TB management expenditures, the median (interquartile range) of total costs by households was Rs.</span></span><span "=""> </span><span style="font-family:Verdana;">58,175 Rs</span><span "=""> </span><span style="font-family:Verdana;">(32,050</span><span style="font-family:Verdana;"> - </span><span style="font-family:Verdana;">97,500). At 20% threshold, 67% of TB patient’s households were affected by catastrophic costs. The determinants of the catastrophic total cost were as follows: patient/guardian employed (adjusted odds ratio [aOR] = 3.428, 95% confidence interval [CI]: 1.900</span><span style="font-family:Verdana;"> - </span><span style="font-family:Verdana;">6.186), patient/guardian the only breadwinner (aOR = 1.751, 95% CI: 1.011</span><span style="font-family:Verdana;"> - </span><span style="font-family:Verdana;">3.032), follow-up visits at current health facility (aOR = 1.352, 95% CI: 1.223</span><span style="font-family:Verdana;"> - </span><span style="font-family:Verdana;">1.494), job loss (aOR = 3.381, 95% CI: 1.512</span><span style="font-family:Verdana;"> - </span><span style="font-family:Verdana;">7.561), and unpaid sick leaves (aOR = 2.862, 95% CI: 1.249</span><span style="font-family:Verdana;"> - </span><span style="font-family:Verdana;">6.558).</span><b><b><span "=""> </span><span style="font-family:Verdana;"><b></b></span><b><b><span style="font-family:Verdana;">Conclusion:</span></b><span style="font-family:Verdana;"></span></b><span style="font-family:Verdana;"> </span></b></b><span style="font-family:Verdana;">The fi</span><span style="font-family:Verdana;">nancial deprivation experienced by patients of low socio-economic status increases as TB treatment proceeds</span><span style="font-family:Verdana;">. This negatively impacts the treatment adherence, resulting in poor treatment outcomes due to income and job loss. Outcomes are exacerbated if the family has single breadwinner and treatment requires follow-up visits.</span> </div>展开更多
Developing the catastrophic medical insurance for urban and rural residents positively is the key action to keep the new round of reform for medical system into deep. However this insurance is the ＇shortage＇ of the ...Developing the catastrophic medical insurance for urban and rural residents positively is the key action to keep the new round of reform for medical system into deep. However this insurance is the ＇shortage＇ of the national health system, so the Shanghai government carries out The Trial Measures for Catastrophic Medical Insurance of urban and rural residents in 2014. In this thesis, we will describe the current situation of the catastrophic medical insurance in Shanghai from aspects of financing, level of compensation, the way to undertake and regulatory. What＇s more, we expect to explore the weakness of catastrophic medical insurance in actual motion, and offer proposals for progressively realizing the integration of urban and rural in medical insurance, improving the basic health care directory, enhancing cooperation with commercial medical insurance.展开更多
This paper evaluates the thermodynamic possibility of coalbed methane formation as a result of direct reaction of coal and water during the process of hydrolytic disproportionation of carbon(HDC).Some examples of expe...This paper evaluates the thermodynamic possibility of coalbed methane formation as a result of direct reaction of coal and water during the process of hydrolytic disproportionation of carbon(HDC).Some examples of experimental and natural evidences of HDC are discussed.展开更多
The International Union of Geological Sciences(IUGS)is evaluating whether there are additional geoscientific activities that would be beneficial in helping mitigate the impacts of tsunami.Public concerns about poor de...The International Union of Geological Sciences(IUGS)is evaluating whether there are additional geoscientific activities that would be beneficial in helping mitigate the impacts of tsunami.Public concerns about poor decisions and inaction,and advances in computing power and data mining call for new scientific approaches.Three fundamental requirements for mitigating impacts of natural hazards are defined.These are:(1)improvement of process-oriented understanding,(2)adequate monitoring and optimal use of data,and(3)generation of advice based on scientific,technical and socio-economic expertise.International leadership/coordination is also important.展开更多
Although the Songnen Plain in the northeastern China was developed relatively late in the temperate zone of the world, its eco-environment has changed greatly. This paper analyzes the changes of land cover and the rat...Although the Songnen Plain in the northeastern China was developed relatively late in the temperate zone of the world, its eco-environment has changed greatly. This paper analyzes the changes of land cover and the rates and trends ofdesertification during the past 100 years in the Songnen Plain. According to the macroscopic analysis, we find that the eco-environment in the plain has reached to the threshold of catastrophic change since the 1950s. The Thom Needle Catastrophic Model was used to determine and validate this conclusion. Human activities, including large-scale construction projects, such as huge dams and dikes, and excessive grazing were the primary factors contributing to regional eco-environmental catastrophe. And irrational reclamation of the wilderness also affected the eco-environmental change. The results reveal the complex human-land interactions.展开更多
Based on the engineering observations of coal and gas outbursts during mining processes and the experimental results,we built a thin plate mechanical model for layered and spalled coal bodies.We studied the mechanical...Based on the engineering observations of coal and gas outbursts during mining processes and the experimental results,we built a thin plate mechanical model for layered and spalled coal bodies.We studied the mechanical mechanism of outbursts,due to instability,of thin plates of coal rocks under the action of in-plane load and normal load,by using the catastrophe theory.The total potential function is derived for the layered rock system,the cusp catastrophe model for the system is established,the bifurcation set that makes the system unstable is given,the process in which gradual change of action forces leads to catastrophic change of state is analyzed,and the effect of movement path of point(P,q) in the control space on the stability of rock plate is analyzed.The study results show that during the process of coal mining,the stability of the layered coal bodies depends not only on its physical properties and dimensions but also on the magnitudes and changing paths of the in-plane load and the normal load.When the gas in the coal bodies ahead of the mining face is pre-drained,the gas pressure can be reduced and the normal load q can be lowered.Consequently,disasters such as coal and gas outbursts can be effectively prevented.展开更多
文摘Landslides are one of the most dangerous natural hazards that cause significant property damage and loss of life.Landslides often destroy farmland,villages,houses,factories,schools,roads and other facilities,injuring humans and livestock.Sometimes,entire towns are devastated by landslides.Due to their pervasiveness,varied triggering factors,and sudden occurrence,landslides are currently one of the most challenging natural disasters to prevent and mitigate.
文摘BACKGROUND Elevated levels of cardiac troponin and abnormal electrocardiogram changes are the primary basis for clinical diagnosis of acute coronary syndrome(ACS).Troponin levels in ACS patients can often be more than 50 times the upper reference limit.Some patients with subarachnoid hemorrhage(SAH)also show electrocardiogram abnormalities,myocardial damage,and elevated cardiac biomarkers.Unlike ACS patients,patients with SAH only have a slight increase in troponin,and the use of anticoagulants or antiplatelet drugs is prohibited.Because of the opposite treatment modalities,it is essential for clinicians to distinguish between SAH and ACS.CASE SUMMARY A 56-year-old female patient was admitted to the emergency department at night with a sudden onset of severe back pain.The final diagnosis was intraspinal hematoma in the thoracic spine.We performed an emergency thoracic spinal canal hematoma evacuation procedure with the assistance of a microscope.Intraoperatively,diffuse hematoma formation was found in the T7-T10 spinal canal,and no obvious spinal vascular malformation changes were observed.Postoperative head and spinal magnetic resonance imaging(MRI)showed a small amount of SAH in the skull,no obvious abnormalities in the cervical and thoracic spinal canals,and no abnormal signals in the lumbar spinal canal.Thoracoab-dominal aorta computed tomography angiography showed no vascular malfor-mation.Postoperative motor system examination showed Medical Research Council Scale grade 1/5 strength in both lower extremities,and the patient experienced decreased sensation below the T12 rib margin and reported a Visual Analog Scale score of 3.CONCLUSION Extremely elevated troponin levels(more than 50 times the normal range)are not unique to coronary artery disease.SAH can also result in extremely high troponin levels,and antiplatelet drugs are contraindicated in such cases.Emergency MRI can help in the early differential diagnosis,as a misdiagnosis of ACS can lead to catastrophic neurological damage in patients with spontaneous spinal SAH.
文摘Increasing population density and development of mountainous terrain have brought human settlements within reach of landslide hazards.In recent years,due to the shortening of return period for severe natural events such as heavy rainfall,snowline retreating,great earthquake together with human activities,catastrophic landslides happened more frequently than before,resulting in large-scale casualties due to the increasing occurrences of rapid long-runout rock avalanches,especially in China.This paper presents some typical case histories related to the catastrophic landslides,including the Guanling rock avalanche,the Yigong rockslide-debris avalanche,the Wenchuan earthquake-induced landslides and the Danba landslide.They occurred in the last decade.Moreover,taking the Jiweishan catastrophic rockslide-fragment flow and the Yuhuangge landslide located in the new Wushan Town for examples,early-warning system and risk management on landslides are discussed in detail.
基金Project supported by Joint Innovative Center for Safe and Effective Mining Technology and Equipment of Coal Resources of Shandong Province,ChinaProject supported by Taishan Scholar Program of Shandong Province,China+2 种基金Project(2014JQJH106)supported by Shandong University of Science and Technology Research Fund,ChinaProject(LAK2012-1)supported by Science and Technology Development Program of Safety Production of Shandong Province,ChinaProject(2012ZHTD06)supported by Science Research Innovative Group of College of Mining and Safety Engineering of Shandong University of Science and Technology,China
文摘Coal mine belt fire develops very rapidly and is difficult to control. If not suppressed quickly, a belt fire could easily lead to airflow disorder and undermine the ventilation system. However, belt fire can be prevented effectively by establishing fire airflow control system. In this work, the 5th belt roadway of Kongzhuang coal mine was taken as the object of investigation, where geometrical models of this roadway were established firstly. Then, based on mathematical model of fire smoke flow, the CO volume fraction, smoke density distribution, air temperature and pollutant velocity vector in the roadway before and after taking airflow control measures were simulated by using Fluent software. It can be known from the simulation that with the normal ventilation status in 5th belt roadway, the countercurrent of smoke does not happen when a fire occurs; the roadway's section is almost filled with CO at 10 m downstream from the fire source, and with air velocity getting stable gradually, the CO concentration reaches about 15 %. After taking airflow control measures, the effect range of temperature field which are harmful to the miners decreases from 69 m to 30 m; and the distance of the roadway fully filled with CO is 5 m farther than that before taking measures. Finally, according to the numerical simulation results and the actual condition of the belt roadway, the warning and automatic remote airflow control system with short-circuit method for the 5th belt roadway was designed to guarantee the safety production.
基金funded by the National Science and Technology Support Program (2015BAK16B02 and 2015BAK16B01)the Fundamental Research Funds of China Academy of Safety Science and Technology
文摘This paper presents a method for analysis of stress and strain of gas pipelines under the effect of horizontal catastrophic landslides. A soil spring model was used to analyze the nonlinear characteristics concerning the mutual effects between the pipeline and the soil. The Ramberg–Osgood model was used to describe the constitutive relations of pipeline materials. This paper also constructed a finite element analysis model using ABAQUS finite element software and studied the distribution of the maximum stress and strain of the pipeline and the axial stress and strain along the pipeline by referencing some typical accident cases. The calculation results indicated that the maximum stress and strain increased gradually with the displacement of landslide.The limit values of pipeline axial stress strain appeared at the junction of the landslide area and non-landslide area. The stress failure criterion was relatively more conservative than the strain failure criterion. The research results of this paper may be used as a technical reference concerning the design and safety management of large-diameter gas pipelines under the effects of catastrophic landslides.
基金financial support by the National Natural Science Foundation of China(Grant Nos.51974186,51774164 and 51774048)。
文摘To reveal the damage characteristics and catastrophic failure mechanism of coal rock caused by gas adsorption,physical tests and theoretical methods are employed.The results show that adsorption swelling can damage coal rock,which can be distinguished by fractal dimension.A fitting relationship between the adsorption damage and fractal dimension is proposed by experimental testing and theoretical analysis.High gas adsorption pressure proves to be the dominant factor that leads to coal failure softening and gas outburst disasters.Three main parameters concerning adsorption damage include the change rate of released energy density,the transition difference in the post-peak acoustic emission(AE)b value and the change rate of cumulative AE energy.Results show that all the three parameters present a step-type decreasing change with the increase in fractal dimension,and the fractal dimension shows a linear relationship within the same failure mode.Finally,a method is proposed to evaluate coal rock disaster transformation,based on the aforementioned three main parameters of adsorption damage.
基金supported by Hubei Provincial Natural Science Foundation of China(No.2012FFC09401)
文摘Abstract： The mathematical model of a high-speed underwater vehicle getting catastrophe in the out-of-water course and a nonlinear sliding mode control with the adaptive backstepping approach for the catastrophic course are proposed. The speed change is large at the moment that the high-speed underwater vehicle launches out of the water to attack an air target. It causes motion parameter uncertainties and affects the precision attack ability. The trajectory angle dynamic characteristic is based on the description of the transformed state-coordinates, the nonlinear sliding mode control is designed to track a linear reference model. Furthermore, the adaptive backstepping control approach is utilized to improve the robustness against the unknown parameter uncertainties. With the proposed control of attitude tracking, the controlled navigational control system possesses the advantages of good transient performance and robustness to parametric uncertainties. These can be predicted and regulated through the design of a linear reference model that has the desired dynamic behavior for the trajectory of the high-speed underwater vehicle to attack its target. Finally, some digital simulation results show that the control system can be applied to a catastrophic course, and that it illustrates great robustness against system parameter uncertainties and external disturbances.
基金supported by the National Natural Science Foundation of China(Grant No.U20A20110)the Second Tibetan Plateau Scientific Expedition and Research Program(Grant No.2019QZKK0906)+2 种基金the Key R&D Projects of Tibet Autonomous Region Science and Technology Pro ject(Grant No.XZ202101ZD0013G)the International Cooperation Overseas Platform Project,CAS(Grant No.131C11KYSB20200033)the Outstanding Talent Project of Thousand Talents Program in China.
文摘The catastrophic rockslide,which frequently triggers numerous severe disasters worldwide,has drawn much attention globally;however,understanding the initiation mechanism of catastrophic rockslides in the absence of typical single triggering factors related to strong seismic activity or torrential precipitation continues to be challenging within the global scientific community.This study aims to determine the mechanism of the three largest catastrophic rockslides in the eastern Tibetan Plateau,Yigong,Xinmo,and Baige,over the past 20 years using field investigation,remote sensing,and runoff analysis.Instead of the conventional driving factors of heavy rainfall and strong earthquakes,the multi-wing butterfly effects(MWBE)of climatic factors and weak earthquakes are for the first time identified as drivers of the catastrophic rockslide disasters.First,strong tectonic uplift,fast fluvial incision,high-density faults,and large regional water confluence formed the slopes in the critical regime,creating the source conditions of rockslide.Second,the MWBE of early dry-heat events and antecedent rainfall,combined with imminent weak earthquakes,initiated rockslide.Third,the delayed amplified runoff moving toward the sliding surface and lowering the strength of the locking-rock segment constituted the fundamental mechanism of the MWBE on rockslide.The catastrophic rockslide was ultimately inferred to be a nonlinear chaotic process;however,prediction and forecasting of rockslide based on the MWBE in the early stages are possible and essential.This finding presents a new perspective concerning forecasting progressive landslides.
基金Financial supports for this work, provided by the National Natural Science Foundation of China (No. 51274097)the Scientific Research Fund of Hunan Provincial Education Department of China (No. 13A020)the Open Projects of State Key Laboratory of Coal Resources and Safe Mining, CUMT (No. 13KF03)
文摘In order to study the mechanism of water inrush from a concealed, confined karst cave, we established a fluid–solid coupling model of water inrush from a concealed karst cave ahead of a roadway and a strength reduction method in a rock pillar for preventing water inrush based on catastrophic theory. Fluid–solid coupling effects and safety margins in a rock pillar were studied. Analysis shows that rock pillar instability, exerted by disturbance stress and seepage stress, is the process of rock pillar catastrophic destabilization induced by nonlinear extension of plastic zones in the rock pillar. Seepage flow emerges in the rock pillar for preventing water inrush, accompanied by mechanical instability of the rock pillar. Taking the accident of a confined karst cave water-inrush of Qiyi Mine as an example, by studying the safety factor of the rock pillar and the relationship between karst cave water pressure and thickness of the rock pillar,it is proposed that rock pillar thickness with a safety factor equal to 1.5 is regarded as the calculated safety thickness of the rock pillar, which should be equal to the sum of the blasthole depth, blasting disturbance depth and the calculated safety thickness of the rock pillar. The cause of the karst water inrush at Qiyi Mine is that the rock pillar was so small that it did not possess a safety margin. Combining fluid–solid coupling theory, catastrophic theory and strength reduction method to study the nonlinear mechanical response of complicated rock engineering, new avenues for quantitative analysis of rock engineering stability evaluation should be forthcoming.
文摘This paper considers the effects of damage softening and hydraulic softening on fault zone media and provides a nonlinear mechanics model of fault earthquake. Taking far field displacement,stiffness ratio and permeation parameter as control variables, we obtain a swallowtail type catastrophic model of earthquakes. Then, by this model, we study the effects of permeation, far field displacement and stiffness ratio on the preparation and the occurrence of earthquakes.
文摘Deep-seated catastrophic landslides,particularly rock or debris avalanches,travel extremely rapidly for long distances,causing severe damage over wide areas.This paper summarizes the geological and geomorphological features of such events,which were induced by earthquakes and rainstorms in Asia,and then uses these features to predict future potential sites of failures.Most of the rock avalanches are preceded by gravitational slope deformation with topographic features,in which small scarps along future head of landslide are the most representative;the scarps can be identified in topographic images made by highresolution airborne LiDAR DEMs and may suggest the instability just before catastrophic failure.
基金Project(51079126) supported by the National Natural Science Foundation of ChinaProject(Y1090971) supported by the Natural Science Foundation of Zhejiang Province, China
文摘A brief review of the former studies on the mechanisms of soil rheology and microstructure is presented. Then a microstructure model and a set of rheological constitutive relations for sott clays, which describe how the rheological consolidation settlement develops, are established in the framework of the catastrophe theory. The validity of this model is verified by a series of rheological consolidation experiments with different loading rates. The experimental data show that creep deformation can be clearly observed in these tests, and the consolidation settlement is loading rate dependent. The characteristics of the deformation can be explained and reproduced successfully using the model. It can be concluded that only the biggest set of voids would collapse for one load increment. Parameters in the model, k and η, are gained by curve fitting. With only two free parameters, good fits of the data are achieved.
文摘The nonlinear and transient vibration of a rotor, which dropped onto back-up bearings when its active magnetic bearings were out of order, was investigated. After strictly deriving its equations of motion and performing numerical simulations, the time-histories of rotating speed of the dropping rotor, and normal force at the rubbing contact point as well as the frequency spectrum of the vibration displacement of back-up bearings are fully analyzed. It is found that the strong and unsteady forced bending vibration of the unbalanced and, damped rotor decelerating through : its first. bending vibtation of the unbalanced and, damped rotor decelerating through its,first critical speed as well as chattering at high frequencies caused by the nonlinearity at the rubbing contact point between, the journal and back-up bearings may lead to the catastrophic damage. of the system.
基金Supported by Sugar Crop Research System(CARS-170303)the Yunling Industry and Technology Leading Talent Training Program(2018LJRC56)+1 种基金Menglian and Changyu Science and Enterprise Cooperation Projectthe Yunnan Province Agriculture Research System.
文摘In recent years,the conditions of continuous warm winter,more rain and high humidity are very beneficial to the breeding and survival of sugarcane diseases and pests.Coupled with the degradation of single varieties,more attention on new plants and less on ratoon cane and the unscientific and unreasonable use of chemical pesticides,the types of sugarcane diseases and pests in the Menglian sugarcane area are increasing day by day,and the damage is increasing year by year,resulting in a substantial reduction in production and sugar,and a serious disaster threat to sugarcane production.Based on the field survey and the current sugarcane production practice in Menglian,this paper systematically reviewed the occurrence and damage dynamics and outbreak reasons of catastrophic diseases and pests that seriously influence sugarcane production,and proposed corresponding prevention and control strategies and integrated prevention and control technology according to the occurrence and damage characteristics of catastrophic diseases and pests.
文摘<div style="text-align:justify;"> <b><span style="font-family:Verdana;">Background:</span></b><span style="font-family:Verdana;"></span><b> </b><span style="font-family:Verdana;">The interplay between financial deprivation and tuberculosis (TB) is considered one of the vital socio-economic determinants of disease. This is the first study of its kind to be carried in Pakistan, which aims to identify leading factors contributing towards catastrophic costs of TB diagnosis and management in order to help policy makers. <b></b></span><b><b><span style="font-family:Verdana;">Methodology:</span></b><span style="font-family:Verdana;"></span></b><b> </b><span style="font-family:Verdana;">From </span><span style="font-family:Verdana;">f</span><span style="font-family:Verdana;">our tertiary care hospitals (TCH) in Islamabad and Rawalpindi</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> 400 TB patients were interviewed through a cross-sectional survey. The patient’s pre and post</span><span style="font-family:Verdana;">-</span><span "=""><span style="font-family:Verdana;">TB income and direct and indirect costs for treatment were analysed following WHO recommendations. Multivariable logistic regression model was used to identify the determinants of catastrophic total cost. <b></b></span><b><b><span style="font-family:Verdana;">Results:</span></b><span style="font-family:Verdana;"><b></b></span><b><b> </b></b></b><span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span><span style="font-family:Verdana;">For TB management expenditures, the median (interquartile range) of total costs by households was Rs.</span></span><span "=""> </span><span style="font-family:Verdana;">58,175 Rs</span><span "=""> </span><span style="font-family:Verdana;">(32,050</span><span style="font-family:Verdana;"> - </span><span style="font-family:Verdana;">97,500). At 20% threshold, 67% of TB patient’s households were affected by catastrophic costs. The determinants of the catastrophic total cost were as follows: patient/guardian employed (adjusted odds ratio [aOR] = 3.428, 95% confidence interval [CI]: 1.900</span><span style="font-family:Verdana;"> - </span><span style="font-family:Verdana;">6.186), patient/guardian the only breadwinner (aOR = 1.751, 95% CI: 1.011</span><span style="font-family:Verdana;"> - </span><span style="font-family:Verdana;">3.032), follow-up visits at current health facility (aOR = 1.352, 95% CI: 1.223</span><span style="font-family:Verdana;"> - </span><span style="font-family:Verdana;">1.494), job loss (aOR = 3.381, 95% CI: 1.512</span><span style="font-family:Verdana;"> - </span><span style="font-family:Verdana;">7.561), and unpaid sick leaves (aOR = 2.862, 95% CI: 1.249</span><span style="font-family:Verdana;"> - </span><span style="font-family:Verdana;">6.558).</span><b><b><span "=""> </span><span style="font-family:Verdana;"><b></b></span><b><b><span style="font-family:Verdana;">Conclusion:</span></b><span style="font-family:Verdana;"></span></b><span style="font-family:Verdana;"> </span></b></b><span style="font-family:Verdana;">The fi</span><span style="font-family:Verdana;">nancial deprivation experienced by patients of low socio-economic status increases as TB treatment proceeds</span><span style="font-family:Verdana;">. This negatively impacts the treatment adherence, resulting in poor treatment outcomes due to income and job loss. Outcomes are exacerbated if the family has single breadwinner and treatment requires follow-up visits.</span> </div>
文摘Developing the catastrophic medical insurance for urban and rural residents positively is the key action to keep the new round of reform for medical system into deep. However this insurance is the ＇shortage＇ of the national health system, so the Shanghai government carries out The Trial Measures for Catastrophic Medical Insurance of urban and rural residents in 2014. In this thesis, we will describe the current situation of the catastrophic medical insurance in Shanghai from aspects of financing, level of compensation, the way to undertake and regulatory. What＇s more, we expect to explore the weakness of catastrophic medical insurance in actual motion, and offer proposals for progressively realizing the integration of urban and rural in medical insurance, improving the basic health care directory, enhancing cooperation with commercial medical insurance.
文摘This paper evaluates the thermodynamic possibility of coalbed methane formation as a result of direct reaction of coal and water during the process of hydrolytic disproportionation of carbon(HDC).Some examples of experimental and natural evidences of HDC are discussed.
文摘The International Union of Geological Sciences(IUGS)is evaluating whether there are additional geoscientific activities that would be beneficial in helping mitigate the impacts of tsunami.Public concerns about poor decisions and inaction,and advances in computing power and data mining call for new scientific approaches.Three fundamental requirements for mitigating impacts of natural hazards are defined.These are:(1)improvement of process-oriented understanding,(2)adequate monitoring and optimal use of data,and(3)generation of advice based on scientific,technical and socio-economic expertise.International leadership/coordination is also important.
基金Under the auspices of the Key Project of Chinese Academy of Sciences (No. KZCX2)
文摘Although the Songnen Plain in the northeastern China was developed relatively late in the temperate zone of the world, its eco-environment has changed greatly. This paper analyzes the changes of land cover and the rates and trends ofdesertification during the past 100 years in the Songnen Plain. According to the macroscopic analysis, we find that the eco-environment in the plain has reached to the threshold of catastrophic change since the 1950s. The Thom Needle Catastrophic Model was used to determine and validate this conclusion. Human activities, including large-scale construction projects, such as huge dams and dikes, and excessive grazing were the primary factors contributing to regional eco-environmental catastrophe. And irrational reclamation of the wilderness also affected the eco-environmental change. The results reveal the complex human-land interactions.
基金provided by the National Natural Science Foundation of China (Nos.50574072, 50874089 and 50534049)the Special Scientific Foundation of the Shaanxi Department of Education (No.08JK366) is gratefully acknowledged
文摘Based on the engineering observations of coal and gas outbursts during mining processes and the experimental results,we built a thin plate mechanical model for layered and spalled coal bodies.We studied the mechanical mechanism of outbursts,due to instability,of thin plates of coal rocks under the action of in-plane load and normal load,by using the catastrophe theory.The total potential function is derived for the layered rock system,the cusp catastrophe model for the system is established,the bifurcation set that makes the system unstable is given,the process in which gradual change of action forces leads to catastrophic change of state is analyzed,and the effect of movement path of point(P,q) in the control space on the stability of rock plate is analyzed.The study results show that during the process of coal mining,the stability of the layered coal bodies depends not only on its physical properties and dimensions but also on the magnitudes and changing paths of the in-plane load and the normal load.When the gas in the coal bodies ahead of the mining face is pre-drained,the gas pressure can be reduced and the normal load q can be lowered.Consequently,disasters such as coal and gas outbursts can be effectively prevented.
