The formation strength plateau of ceramics is addressed. A set of of 99A1203 are conducted, mechanism of the residual subjected to thermal shock thermal shock experiments where the thin specimens of 1 mm× 10 mm&...The formation strength plateau of ceramics is addressed. A set of of 99A1203 are conducted, mechanism of the residual subjected to thermal shock thermal shock experiments where the thin specimens of 1 mm× 10 mm×50 mm exhibit parallel through edge cracks, and thus permit quantitative measurements of the crack patterns. The cracks evolve with the severity of ther- mal shock. It is found that there is a correlation between the length and density of the thermal shock cracks. The increase of crack length weakens the residual strength, whereas the increase of crack density improves it. In a considerably wide temperature range, the two contrary effects just counteract each other; consequently a plateau appears in the variation curve of the residual strength. A comparison between the numerical and experimental results of the residual strength is made, and they are found in good agreement. This work is helpful to a deep understanding of the thermal shock failure of ceramics.展开更多
Traffic is an indispensable prerequisite for a tourism system. The ＂four vertical and four horizontal＂ HSR network represents an important milestone of the ＂traffic revolution＂ in China. It will affect the spatial...Traffic is an indispensable prerequisite for a tourism system. The ＂four vertical and four horizontal＂ HSR network represents an important milestone of the ＂traffic revolution＂ in China. It will affect the spatial pattern of tourism accessibility in Chinese cities, thus substan- tially increasing their power to attract tourists and their radiation force. This paper examines the evolution and spatial characteristics of the power to attract tourism of cities linked by China＇s HSR network by measuring the influence of accessibility of 338 HSR-linked cities using GIS analysis. The results show the following. （1） The accessibility of Chinese cities is optimized by the HSR network, whose spatial pattern of accessibility exhibits an obvious traf- fic direction and causes a high-speed rail-corridor effect. （2） The spatial pattern of tourism field strength in Chinese cities exhibits the dual characteristics of multi-center annular diver- gence and dendritic diffusion. Dendritic diffusion is particularly more obvious along the HSR line. The change rate of urban tourism field strength forms a high-value corridor along the HSR line and exhibits a spatial pattern of decreasing area from the center to the outer limit along the HSR line. （3） The influence of the higher and highest tourism field strength areas along the HSR line is most significant, and the number of cities that distribute into these two types of tourism field strengths significantly increases： their area expands by more than 100% HSR enhances the tourism field strength value of regional central cities, and the radiation range of tourism attraction extends along the HSR line.展开更多
Intact rock-like specimens and specimens that include a single, smooth planar joint at various angles are prepared for split Hopkinson pressure bar（SHPB） testing. A buffer pad between the striker bar and the inciden...Intact rock-like specimens and specimens that include a single, smooth planar joint at various angles are prepared for split Hopkinson pressure bar（SHPB） testing. A buffer pad between the striker bar and the incident bar of an SHPB apparatus is used to absorb some of the shock energy. This can generate loading rates of 20.2-4627.3 GPa/s, enabling dynamic peak stresses/strengths and associated failure patterns of the specimens to be investigated. The effects of the loading rate and angle of load applied on the dynamic peak stresses/strengths of the specimens are examined. Relevant experimental results demonstrate that the failure pattern of each specimen can be classified as four types： Type A, integrated with or without tiny flake-off; Type B, slide failure; Type C, fracture failure; and Type D, crushing failure. The dynamic peak stresses/strengths of the specimens that have similar failure patterns increase linearly with the loading rate, yielding high correlations that are evident on semi-logarithmic plots. The slope of the failure envelope is the smallest for slide failure, followed by crushing failure, and that of fracture failure is the largest. The magnitude of the plot slope of the dynamic peak stress against the loading rate for the specimens that are still integrated after testing is between that of slide failure and crushing failure. The angle of application has a limited effect on the dynamic peak stresses/strengths of the specimens regardless of the failure pattern, but it affects the bounds of the loading rates that yield each failure pattern, and thus influences the dynamic responses of the single jointed specimen. Slide failure occurs at the lowest loading rate of any failure, but can only occur in single jointed specimen that allows sliding.Crushing failure is typically associated with the largest loading rate, and fracture failure may occur when the loading rate is between the boundaries for slide failure and crushing failure.展开更多
The results of a theoretical study on the influence of strength of interphase boundaries in metal-ceramic composite on macroscopical characteristics of composite response such as strength, deformation capacity, fractu...The results of a theoretical study on the influence of strength of interphase boundaries in metal-ceramic composite on macroscopical characteristics of composite response such as strength, deformation capacity, fracture energy and fracture pattern are presented. The study was conducted by means of computer-aided simulation by means of movable cellular automaton method taking account of a developed ＂mesoscopical＂ structural model of particle-reinforced composite. The strength of interphase boundaries is found to be a key structural factor determining not only the strength properties of metal-ceramic composite, but also the pattern and rate of fracture. The principles for achievement of the high-strength values of particle/binder interfaces in the metal-ceramic composition due to the formation of the wide transition zones （areas of variable chemical composition） at the interphase boundaries are discussed. Simulation results confirm that such transition zones provide a change in fracture mechanism and make the achievement of a high-strength and a high deformation capacity of metal-ceramic composite possible.展开更多
AIM:To investigate the prevalence of chronic dyspnea and its relationship to respiratory muscle function in end-stage liver disease.METHODS:Sixty-eight consecutive,ambulatory,Caucasian patients with end-stage liver di...AIM:To investigate the prevalence of chronic dyspnea and its relationship to respiratory muscle function in end-stage liver disease.METHODS:Sixty-eight consecutive,ambulatory,Caucasian patients with end-stage liver disease,candidates for liver transplantation,were referred for preoperative respiratory function assessment.Forty of these(29 men) were included in this preliminary study after applying strict inclusion and exclusion criteria.Seventeen of 40 patients(42%) had ascites,but none of them was cachectic.Fifteen of 40 patients(38%)had a history of hepatic encephalopathy,though none of them was symptomatic at study time.All patients with a known history and/or presence of co-morbidities were excluded.Chronic dyspnea was rated according to the modified medical research council(mMRC) 6-point scale.Liver disease severity was assessed according to the Model for end-stage liver disease(MELD).Routine lung function tests,maximum static expiratory(Pemax) and inspiratory(Pimax) mouth pressures were measured.Respiratory muscle strength(RMS) was calculated from Pimax and Pemax values.In addition,arterial blood gases and pattern of breathing(VE:minute ventilation;VT:tidal volume;VT/TI:mean inspiratory flow;TI:duration of inspiration) were measured.RESULTS:Thirty-five(88%) of 40 patients aged(mean ± SD) 52 ± 10 years reported various degrees of chronic dyspnea(mMRC),ranging from 0 to 4,with a mean value of 2.0 ± 1.2.MELD score was 14 ± 6.Pemax,percent of predicted(%pred) was 105 ± 35,Pimax,%pred was 90 ± 29,and RMS,%pred was 97 ± 30.These pressures were below the normal limits in 12(30%),15(38%),and 14(35%) patients,respectively.Furthermore,comparing the subgroups of ascites to non-ascites patients,all respiratory muscle indices measured were found significantly decreased in ascites patients.Patients with ascites also had a significantly worse MELD score compared to non-ascites ones(P = 0.006).Significant correlations were found between chronic dyspnea and respiratory muscle function indices in all patients.Specifically,mMRC score was significantly correlated with Pemax,Pimax,and RMS(r =-0.53,P < 0.001;r =-0.42,P < 0.01;r =-0.51,P < 0.001,respectively).These correlations were substantially closer in the non-ascites subgroup(r =-0.82,P < 0.0001;r =-0.61,P < 0.01;r =-0.79,P < 0.0001,respectively) compared to all patients.Similar results were found for the relationship between mMRC vs MELD score,and MELD score vs respiratory muscle strength indices.In all patients the sole predictor of mMRC score was RMS(r =-0.51,P < 0.001).In the subgroup of patients without ascites this relationship becomes closer(r =-0.79,P < 0.001),whilst this relationship breaks down in the subgroup of patients with ascites.The disappearance of such a correlation may be due to the fact that ascites acts as a "confounding" factor.PaCO2(4.4 ± 0.5 kPa) was increased,whereas pH(7.49 ± 0.04) was decreased in 26(65%) and 34(85%) patients,respectively.PaO2(12.3 ± 0.04 kPa) was within normal limits.VE(11.5 ± 3.5 L/min),VT(0.735 ± 0.287 L),and VT/TI(0.449±0.129 L/s) were increased signifying hyperventilation in both subgroups of patients.VT/TI was significantly higher in patients with ascites than without ascites.Significant correlations,albeit weak,were found for PaCO2 with VE and VT/TI(r =-0.44,P < 0.01;r =-0.41,P < 0.01,respectively).CONCLUSION:The prevalence of chronic dyspnea is 88% in end-stage liver disease.The mMRC score closely correlates with respiratory muscle strength.展开更多
配价理论的基本假设是动词在句子中处于核心地位,因其决定了构成一个完整句法结构所必需的补足语数量。配价型式可以对动词的语义和句法特征进行深度描写,帮助学习者更好掌握英语句子。本研究对两个自建的论文摘要语料库(学习者语料库...配价理论的基本假设是动词在句子中处于核心地位,因其决定了构成一个完整句法结构所必需的补足语数量。配价型式可以对动词的语义和句法特征进行深度描写,帮助学习者更好掌握英语句子。本研究对两个自建的论文摘要语料库(学习者语料库和国际期刊语料库)中高频动词进行了对比分析。研究发现,与期刊语料库相比,学习者语料中provide在动词原形和第三人称单数上存在使用不足现象;不足具体体现在二价型式结构S V Obj的使用上,在三价的型式结构SV Obj for nom和SV Obj with nom存在过度使用;配价力的计算结果显示,在国际期刊语料中SV Obj for nom的配价强度值最大,是provide最典型的配价型式。总之,学习者在学术语境中对高频动词(如provide)的典型形式(动词原形和第三人称单数)及典型配价型式(如S V Obj for nom)存在使用不足现象。研究结果对学术英语写作及其课堂实践有一定的借鉴意义。展开更多
基金supported by the National Natural Science Foundations of China (10972020,11061130550)Fundamental Research Funds for the Central UniversitiesNational Agency for Research of France (International project T-shock)
文摘The formation strength plateau of ceramics is addressed. A set of of 99A1203 are conducted, mechanism of the residual subjected to thermal shock thermal shock experiments where the thin specimens of 1 mm× 10 mm×50 mm exhibit parallel through edge cracks, and thus permit quantitative measurements of the crack patterns. The cracks evolve with the severity of ther- mal shock. It is found that there is a correlation between the length and density of the thermal shock cracks. The increase of crack length weakens the residual strength, whereas the increase of crack density improves it. In a considerably wide temperature range, the two contrary effects just counteract each other; consequently a plateau appears in the variation curve of the residual strength. A comparison between the numerical and experimental results of the residual strength is made, and they are found in good agreement. This work is helpful to a deep understanding of the thermal shock failure of ceramics.
基金Foundation： National Natural Science Foundation of China, No. 41271134
文摘Traffic is an indispensable prerequisite for a tourism system. The ＂four vertical and four horizontal＂ HSR network represents an important milestone of the ＂traffic revolution＂ in China. It will affect the spatial pattern of tourism accessibility in Chinese cities, thus substan- tially increasing their power to attract tourists and their radiation force. This paper examines the evolution and spatial characteristics of the power to attract tourism of cities linked by China＇s HSR network by measuring the influence of accessibility of 338 HSR-linked cities using GIS analysis. The results show the following. （1） The accessibility of Chinese cities is optimized by the HSR network, whose spatial pattern of accessibility exhibits an obvious traf- fic direction and causes a high-speed rail-corridor effect. （2） The spatial pattern of tourism field strength in Chinese cities exhibits the dual characteristics of multi-center annular diver- gence and dendritic diffusion. Dendritic diffusion is particularly more obvious along the HSR line. The change rate of urban tourism field strength forms a high-value corridor along the HSR line and exhibits a spatial pattern of decreasing area from the center to the outer limit along the HSR line. （3） The influence of the higher and highest tourism field strength areas along the HSR line is most significant, and the number of cities that distribute into these two types of tourism field strengths significantly increases： their area expands by more than 100% HSR enhances the tourism field strength value of regional central cities, and the radiation range of tourism attraction extends along the HSR line.
基金the Science and Technology authority of Taiwan, China, for financially supporting this research under Grant No.NSC 102-2221-E-027-071-MY3
文摘Intact rock-like specimens and specimens that include a single, smooth planar joint at various angles are prepared for split Hopkinson pressure bar（SHPB） testing. A buffer pad between the striker bar and the incident bar of an SHPB apparatus is used to absorb some of the shock energy. This can generate loading rates of 20.2-4627.3 GPa/s, enabling dynamic peak stresses/strengths and associated failure patterns of the specimens to be investigated. The effects of the loading rate and angle of load applied on the dynamic peak stresses/strengths of the specimens are examined. Relevant experimental results demonstrate that the failure pattern of each specimen can be classified as four types： Type A, integrated with or without tiny flake-off; Type B, slide failure; Type C, fracture failure; and Type D, crushing failure. The dynamic peak stresses/strengths of the specimens that have similar failure patterns increase linearly with the loading rate, yielding high correlations that are evident on semi-logarithmic plots. The slope of the failure envelope is the smallest for slide failure, followed by crushing failure, and that of fracture failure is the largest. The magnitude of the plot slope of the dynamic peak stress against the loading rate for the specimens that are still integrated after testing is between that of slide failure and crushing failure. The angle of application has a limited effect on the dynamic peak stresses/strengths of the specimens regardless of the failure pattern, but it affects the bounds of the loading rates that yield each failure pattern, and thus influences the dynamic responses of the single jointed specimen. Slide failure occurs at the lowest loading rate of any failure, but can only occur in single jointed specimen that allows sliding.Crushing failure is typically associated with the largest loading rate, and fracture failure may occur when the loading rate is between the boundaries for slide failure and crushing failure.
基金The investigation has been carried out within the SB RAS Program Ⅲ.20.2 for Basic Researchat partial financial support of the RFBR Grant No.11-08-12069-ofi-m-2011+1 种基金the Project No.5 of the Belarus NASSB RAS Program for Joint Basic Research
文摘The results of a theoretical study on the influence of strength of interphase boundaries in metal-ceramic composite on macroscopical characteristics of composite response such as strength, deformation capacity, fracture energy and fracture pattern are presented. The study was conducted by means of computer-aided simulation by means of movable cellular automaton method taking account of a developed ＂mesoscopical＂ structural model of particle-reinforced composite. The strength of interphase boundaries is found to be a key structural factor determining not only the strength properties of metal-ceramic composite, but also the pattern and rate of fracture. The principles for achievement of the high-strength values of particle/binder interfaces in the metal-ceramic composition due to the formation of the wide transition zones （areas of variable chemical composition） at the interphase boundaries are discussed. Simulation results confirm that such transition zones provide a change in fracture mechanism and make the achievement of a high-strength and a high deformation capacity of metal-ceramic composite possible.
文摘AIM:To investigate the prevalence of chronic dyspnea and its relationship to respiratory muscle function in end-stage liver disease.METHODS:Sixty-eight consecutive,ambulatory,Caucasian patients with end-stage liver disease,candidates for liver transplantation,were referred for preoperative respiratory function assessment.Forty of these(29 men) were included in this preliminary study after applying strict inclusion and exclusion criteria.Seventeen of 40 patients(42%) had ascites,but none of them was cachectic.Fifteen of 40 patients(38%)had a history of hepatic encephalopathy,though none of them was symptomatic at study time.All patients with a known history and/or presence of co-morbidities were excluded.Chronic dyspnea was rated according to the modified medical research council(mMRC) 6-point scale.Liver disease severity was assessed according to the Model for end-stage liver disease(MELD).Routine lung function tests,maximum static expiratory(Pemax) and inspiratory(Pimax) mouth pressures were measured.Respiratory muscle strength(RMS) was calculated from Pimax and Pemax values.In addition,arterial blood gases and pattern of breathing(VE:minute ventilation;VT:tidal volume;VT/TI:mean inspiratory flow;TI:duration of inspiration) were measured.RESULTS:Thirty-five(88%) of 40 patients aged(mean ± SD) 52 ± 10 years reported various degrees of chronic dyspnea(mMRC),ranging from 0 to 4,with a mean value of 2.0 ± 1.2.MELD score was 14 ± 6.Pemax,percent of predicted(%pred) was 105 ± 35,Pimax,%pred was 90 ± 29,and RMS,%pred was 97 ± 30.These pressures were below the normal limits in 12(30%),15(38%),and 14(35%) patients,respectively.Furthermore,comparing the subgroups of ascites to non-ascites patients,all respiratory muscle indices measured were found significantly decreased in ascites patients.Patients with ascites also had a significantly worse MELD score compared to non-ascites ones(P = 0.006).Significant correlations were found between chronic dyspnea and respiratory muscle function indices in all patients.Specifically,mMRC score was significantly correlated with Pemax,Pimax,and RMS(r =-0.53,P < 0.001;r =-0.42,P < 0.01;r =-0.51,P < 0.001,respectively).These correlations were substantially closer in the non-ascites subgroup(r =-0.82,P < 0.0001;r =-0.61,P < 0.01;r =-0.79,P < 0.0001,respectively) compared to all patients.Similar results were found for the relationship between mMRC vs MELD score,and MELD score vs respiratory muscle strength indices.In all patients the sole predictor of mMRC score was RMS(r =-0.51,P < 0.001).In the subgroup of patients without ascites this relationship becomes closer(r =-0.79,P < 0.001),whilst this relationship breaks down in the subgroup of patients with ascites.The disappearance of such a correlation may be due to the fact that ascites acts as a "confounding" factor.PaCO2(4.4 ± 0.5 kPa) was increased,whereas pH(7.49 ± 0.04) was decreased in 26(65%) and 34(85%) patients,respectively.PaO2(12.3 ± 0.04 kPa) was within normal limits.VE(11.5 ± 3.5 L/min),VT(0.735 ± 0.287 L),and VT/TI(0.449±0.129 L/s) were increased signifying hyperventilation in both subgroups of patients.VT/TI was significantly higher in patients with ascites than without ascites.Significant correlations,albeit weak,were found for PaCO2 with VE and VT/TI(r =-0.44,P < 0.01;r =-0.41,P < 0.01,respectively).CONCLUSION:The prevalence of chronic dyspnea is 88% in end-stage liver disease.The mMRC score closely correlates with respiratory muscle strength.
文摘配价理论的基本假设是动词在句子中处于核心地位,因其决定了构成一个完整句法结构所必需的补足语数量。配价型式可以对动词的语义和句法特征进行深度描写,帮助学习者更好掌握英语句子。本研究对两个自建的论文摘要语料库(学习者语料库和国际期刊语料库)中高频动词进行了对比分析。研究发现,与期刊语料库相比,学习者语料中provide在动词原形和第三人称单数上存在使用不足现象;不足具体体现在二价型式结构S V Obj的使用上,在三价的型式结构SV Obj for nom和SV Obj with nom存在过度使用;配价力的计算结果显示,在国际期刊语料中SV Obj for nom的配价强度值最大,是provide最典型的配价型式。总之,学习者在学术语境中对高频动词(如provide)的典型形式(动词原形和第三人称单数)及典型配价型式(如S V Obj for nom)存在使用不足现象。研究结果对学术英语写作及其课堂实践有一定的借鉴意义。
