This study investigates the instability characteristics of dynamic disasters resulting from disruption caused by extracting resources underground. Utilizing the split Hopkinson pressure bar (SHPB) system, the dynamic ...This study investigates the instability characteristics of dynamic disasters resulting from disruption caused by extracting resources underground. Utilizing the split Hopkinson pressure bar (SHPB) system, the dynamic response mechanism of coal energy evolution is examined, and the energy instability criterion is established. The validity of the instability criterion is explored from the standpoint of damage progression. The results demonstrate that the energy conversion mechanism undergoes a fundamental alternation under impact disturbance. Moreover, the energy release rate as well as the energy dissipation rate undergo comparable changes across distinct levels of impact disturbance. The distinction between the energy release rate and the energy dissipation rate (DRD) increases as coal mass deformation grows. Prior to coal facing instability and failure, the DRD experienced an inflection point followed by a sharp decrease. In conjunction with the discussion on the damage evolution, the physical and mechanical significance of DRD remains clear, which can essentially describe the whole impact loading process. The phenomenon that the inflection point appears and DRD subsequently suddenly decreases can be employed as the energy criterion prior to the failure of instability. Furthermore, this paper provides significant reference for the prediction of dynamic instability of coal under dynamic disturbance.展开更多
Types and characteristics of gastric dysplasia werestudied histopathologically. Besides the adenomatous,cryptal and globoid dysplasias, regenerative type of gas-tric dysplasia was described, especially about its histo...Types and characteristics of gastric dysplasia werestudied histopathologically. Besides the adenomatous,cryptal and globoid dysplasias, regenerative type of gas-tric dysplasia was described, especially about its histo-pathological features and histogenesis. The peculiarityof this type of gastric dysplasia just coincided with thefindings of gastric mucosal changes found in the inhabitantsliving in Liaodong Panisula-a high incidence area ofgastric cancer. According to the epidemiologic and histo-pathologic studies on the inhabitants of Zhuanghe Countyof Liaodong Panisula, it was found that high salted foodse.g. the salted pork and fish etc. showed strongmutagenecity. The authors detected that these were therisk factors and might be the leading cause of the gastricmucosal erosions and following by epithelial regenerativechanges. Malignant changes were detected in the regene-rative dysplastic lesions in pathologic sections. Therefore,gastric mucosal regeneration should not be oper looked asa precursor of gastric cancer in some cases.展开更多
The anoxic decomposition and influence of carbon precursors on the properties of LiFePO_4/C prepared by using Fe_2O_3 were investigated.X-ray powder diffractometry,Fourier transform infrared spectroscopy(FTIR),scannin...The anoxic decomposition and influence of carbon precursors on the properties of LiFePO_4/C prepared by using Fe_2O_3 were investigated.X-ray powder diffractometry,Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM) and carbon content and charge–discharge tests were applied to the characterization of the as-synthesized cathodes.Partial carbon is lost in the anaerobic decomposition of organic precursors and a high hydrogen content leads to a high residual carbon rate.Pyromellitic anhydride and citric acid participate in reactions before and in ball-milling.All the chosen carbon precursors are capable of producing LiFePO_4 with high degree of crystallinity and purity.The carbon derived from α-D-glucose,pyromellitic anhydride,soluble starch,citric acid and polyacrylamide has a loose and porous texture in LiFePO_4/C which forms conduction on and between LiFePO_4 particles.LiFePO_4/C prepared by using α-D-glucose,pyromellitic anhydride,citric acid and sucrose exhibits appreciable electrochemical performance.Graphite alone is able to enhance the electrochemical performance of LiFePO_4 to a limited extent but incapable of preparing practical cathode.展开更多
In this paper, we investigate the precursors of large earthquakes in the eastern region of Taiwan by means of the reverse tracing of precursors. We discuss the parameters which are suitable for the seismic chains and ...In this paper, we investigate the precursors of large earthquakes in the eastern region of Taiwan by means of the reverse tracing of precursors. We discuss the parameters which are suitable for the seismic chains and intermedi- ate-term patterns in this region and obtain the threshold of the patterns. Applying the linear discriminate method to the intermediate-term patterns of seismic chains, we present an approach for exploring the precursors of large earthquakes. The results show that this method can reduce the false alarm rate for large earthquakes in this region, and the reverse tracing of precursors can be applied to the eastern region of Taiwan.展开更多
Local segregation in Cu-In precursors and its effects on the element distribution and microstructures of selenized CuInSe2 thin films were investigated. Cu-In precursors with an ideal total mole ratio of Cu to In of 0...Local segregation in Cu-In precursors and its effects on the element distribution and microstructures of selenized CuInSe2 thin films were investigated. Cu-In precursors with an ideal total mole ratio of Cu to In of 0.92 were prepared by middle frequency alternating current magnetron sputtering with Cu-In alloy target, then CuInSe2 absorbers for solar cells were formed by selenization process in selenium atmosphere. Scanning electron microscope and energy dispersive X-ray spectroscope were used respectively to observe the surface morphologies and determine the compositions of both Cu-In precursors and CuInSe2 thin films. Their microstructures were characterized by X-ray diffractometry and Raman spectroscope. The results show that Cu-In precursors are mainly composed of (Cu11In9) phase with In-rich solid solution. Stoichiometric CuInSe2 thin films with a homogeneous element distribution and single chalcopyrite phase can be synthesized from a segregated Cu-In precursor film with an ideal total mole ratio of Cu to In of 0.92. CuInSe2 thin film shows P-type conductivity and its resistivity reaches 1.2×103Ω·cm.展开更多
Granite is usually composed of quartz,biotite,feldspar,and cracks,and the variation characteristics of these components could reflect the deformation and failure process of rock well.Taking granite as an example,the v...Granite is usually composed of quartz,biotite,feldspar,and cracks,and the variation characteristics of these components could reflect the deformation and failure process of rock well.Taking granite as an example,the video camera was used to record the deformation and failure process of rock.The distribution of meso-components in video images was then identified.The meso-components of rock failure precursors were also discussed.Moreover,a modified LSTM(long short-term memory method)based on SSA(sparrow search algorithm)was proposed to estimate the change of meso-components of rock failure precursor.It shows that the initiation and expansion of cracks are mainly caused by feldspar and quartz fracture,and when the quartz and feldspar exit the stress framework,rock failure occurs;the second large increase of crack area and the second large decrease of quartz or feldspar area may be used as a precursor of rock failure;the precursor time of rock failure based on meso-scopic components is about 4 s earlier than that observed by the naked eye;the modified LSTM network has the strongest estimation ability for quartz area change,followed by feldspar and biotite,and has the worst estimation ability for cracks;when using the modified LSTM network to predict the precursors of rock instability and failure,quartz and feldspar could be given priority.The results presented herein may provide reference in the investigation of rock failure mechanism.展开更多
基金Projects(51934007,12072363,52004268) supported by the National Natural Science Foundation of ChinaProject(22KJD440002) supported by the Natural Science Fund for Colleges and Universities in Jiangsu Province,China。
文摘This study investigates the instability characteristics of dynamic disasters resulting from disruption caused by extracting resources underground. Utilizing the split Hopkinson pressure bar (SHPB) system, the dynamic response mechanism of coal energy evolution is examined, and the energy instability criterion is established. The validity of the instability criterion is explored from the standpoint of damage progression. The results demonstrate that the energy conversion mechanism undergoes a fundamental alternation under impact disturbance. Moreover, the energy release rate as well as the energy dissipation rate undergo comparable changes across distinct levels of impact disturbance. The distinction between the energy release rate and the energy dissipation rate (DRD) increases as coal mass deformation grows. Prior to coal facing instability and failure, the DRD experienced an inflection point followed by a sharp decrease. In conjunction with the discussion on the damage evolution, the physical and mechanical significance of DRD remains clear, which can essentially describe the whole impact loading process. The phenomenon that the inflection point appears and DRD subsequently suddenly decreases can be employed as the energy criterion prior to the failure of instability. Furthermore, this paper provides significant reference for the prediction of dynamic instability of coal under dynamic disturbance.
基金This research was supported by the National "7.5" Research Grant on Cancer.
文摘Types and characteristics of gastric dysplasia werestudied histopathologically. Besides the adenomatous,cryptal and globoid dysplasias, regenerative type of gas-tric dysplasia was described, especially about its histo-pathological features and histogenesis. The peculiarityof this type of gastric dysplasia just coincided with thefindings of gastric mucosal changes found in the inhabitantsliving in Liaodong Panisula-a high incidence area ofgastric cancer. According to the epidemiologic and histo-pathologic studies on the inhabitants of Zhuanghe Countyof Liaodong Panisula, it was found that high salted foodse.g. the salted pork and fish etc. showed strongmutagenecity. The authors detected that these were therisk factors and might be the leading cause of the gastricmucosal erosions and following by epithelial regenerativechanges. Malignant changes were detected in the regene-rative dysplastic lesions in pathologic sections. Therefore,gastric mucosal regeneration should not be oper looked asa precursor of gastric cancer in some cases.
基金Project(2010ZC051)supported by Natural Science Foundation of Yunnan Province,ChinaProject(20140439)supported by Analysis and Testing Foundation of Kuming University of Science and Technology,ChinaProject(14118245)supported by the Starting Research Fund from Kunming University of Science and Technology,China
文摘The anoxic decomposition and influence of carbon precursors on the properties of LiFePO_4/C prepared by using Fe_2O_3 were investigated.X-ray powder diffractometry,Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM) and carbon content and charge–discharge tests were applied to the characterization of the as-synthesized cathodes.Partial carbon is lost in the anaerobic decomposition of organic precursors and a high hydrogen content leads to a high residual carbon rate.Pyromellitic anhydride and citric acid participate in reactions before and in ball-milling.All the chosen carbon precursors are capable of producing LiFePO_4 with high degree of crystallinity and purity.The carbon derived from α-D-glucose,pyromellitic anhydride,soluble starch,citric acid and polyacrylamide has a loose and porous texture in LiFePO_4/C which forms conduction on and between LiFePO_4 particles.LiFePO_4/C prepared by using α-D-glucose,pyromellitic anhydride,citric acid and sucrose exhibits appreciable electrochemical performance.Graphite alone is able to enhance the electrochemical performance of LiFePO_4 to a limited extent but incapable of preparing practical cathode.
文摘In this paper, we investigate the precursors of large earthquakes in the eastern region of Taiwan by means of the reverse tracing of precursors. We discuss the parameters which are suitable for the seismic chains and intermedi- ate-term patterns in this region and obtain the threshold of the patterns. Applying the linear discriminate method to the intermediate-term patterns of seismic chains, we present an approach for exploring the precursors of large earthquakes. The results show that this method can reduce the false alarm rate for large earthquakes in this region, and the reverse tracing of precursors can be applied to the eastern region of Taiwan.
基金Project(2004AA513023) supported by the National High Technology Research and Development Program of China
文摘Local segregation in Cu-In precursors and its effects on the element distribution and microstructures of selenized CuInSe2 thin films were investigated. Cu-In precursors with an ideal total mole ratio of Cu to In of 0.92 were prepared by middle frequency alternating current magnetron sputtering with Cu-In alloy target, then CuInSe2 absorbers for solar cells were formed by selenization process in selenium atmosphere. Scanning electron microscope and energy dispersive X-ray spectroscope were used respectively to observe the surface morphologies and determine the compositions of both Cu-In precursors and CuInSe2 thin films. Their microstructures were characterized by X-ray diffractometry and Raman spectroscope. The results show that Cu-In precursors are mainly composed of (Cu11In9) phase with In-rich solid solution. Stoichiometric CuInSe2 thin films with a homogeneous element distribution and single chalcopyrite phase can be synthesized from a segregated Cu-In precursor film with an ideal total mole ratio of Cu to In of 0.92. CuInSe2 thin film shows P-type conductivity and its resistivity reaches 1.2×103Ω·cm.
基金Project(41472254)supported by the National Natural Science Foundation of China。
文摘Granite is usually composed of quartz,biotite,feldspar,and cracks,and the variation characteristics of these components could reflect the deformation and failure process of rock well.Taking granite as an example,the video camera was used to record the deformation and failure process of rock.The distribution of meso-components in video images was then identified.The meso-components of rock failure precursors were also discussed.Moreover,a modified LSTM(long short-term memory method)based on SSA(sparrow search algorithm)was proposed to estimate the change of meso-components of rock failure precursor.It shows that the initiation and expansion of cracks are mainly caused by feldspar and quartz fracture,and when the quartz and feldspar exit the stress framework,rock failure occurs;the second large increase of crack area and the second large decrease of quartz or feldspar area may be used as a precursor of rock failure;the precursor time of rock failure based on meso-scopic components is about 4 s earlier than that observed by the naked eye;the modified LSTM network has the strongest estimation ability for quartz area change,followed by feldspar and biotite,and has the worst estimation ability for cracks;when using the modified LSTM network to predict the precursors of rock instability and failure,quartz and feldspar could be given priority.The results presented herein may provide reference in the investigation of rock failure mechanism.
