The rigid body limit equilibrium method(RBLEM) and finite element method(FEM) are two widely used approaches for rock slope's stability analysis currently. RBLEM introduced plethoric assumptions; while traditional...The rigid body limit equilibrium method(RBLEM) and finite element method(FEM) are two widely used approaches for rock slope's stability analysis currently. RBLEM introduced plethoric assumptions; while traditional FEM relied on artificial factors when determining factor of safety(FOS) and sliding surfaces. Based on the definition of structure instability that an elasto-plastic structure is not stable if it is unable to satisfy simultaneously equilibrium condition, kinematical admissibility and constitutive equations under given external loads, deformation reinforcement theory(DRT) is developed. With this theory, plastic complementary energy(PCE) can be used to evaluate the overall stability of rock slope, and the unbalanced force beyond the yield surface could be the identification of local failure. Compared with traditional slope stability analysis approaches, the PCE norm curve to strength reduced factor is introduced and the unbalanced force is applied to the determination of key sliding surfaces and required reinforcement. Typical and important issues in rock slope stability are tested in TFINE(a three-dimensional nonlinear finite element program), which is further applied to several representatives of high rock slope's stability evaluation and reinforcement engineering practice in southwest of China.展开更多
Objective： Detection of abdominal in- jury is a very important component in trauma management, so a precise assessment of liver and spleen injuries includ- ing their severity degree is necessary. There is a good case...Objective： Detection of abdominal in- jury is a very important component in trauma management, so a precise assessment of liver and spleen injuries includ- ing their severity degree is necessary. There is a good case to believe that in emergency situations the radiologists＇ performance may profit from a systematic approach using established scoring systems. Score systems as the organ injury scale （OIS） drawn up by the American Association for the Surgery of Trauma are a valuable guidance for objec- tive trauma assessment. Aim of this study was to evaluate retrospectively whether a structured approach using the OIS may help improve trauma assessment. Methods： Fifty-three patients, 38 male and 15 female who underwent CT and laparotomy after abdominal trauma were included in this study. The laparotomy was performed by experienced surgeons with a minimum experience of 6 years. While the original CT reports were written by differ- ent radiologists with a minimum experience of 3 years, and then a radiologist with experience of 4 years reviewed the same original CT pictures, resulting in the structured report. Both the original and structured CT results on liver and spleen injuries were transferred into OIS grades. Finally, the initial and structured CT results were compared with theintraoperative findings gathered from the surgery report. Results： Regarding the original CT report we found a mean divergence of 0.68±0.8 （r=-0.45） to the OIS finding in the surgery report for liver injuries （0.69±1.17 for spleen injuries; r=-0.69）. In comparison with the structured approach, where we detected a divergence of 0.8±0.68; r=-0.63 （0.47±0.77 for spleen injuries; r=0.91）, there was no significant difference. However we detected a lower rate of over-diag- nosis in structured approaches. Conclusion： Our study shows that a structured ap- proach to triage abdominal trauma using an imaging check- list does not lead to a significantly higher detection rate, but a nonsignificant trend to reduce the rate of over- diagnoses, thus being more precise in grading the severity grade. Concerning the bias by retrospective study design, further prospective investigations are needed to evaluate the impact of trauma scores on the workflow in emergency department procedure as structured reporting systems are a valuable guidance in other radiological disciplines.展开更多
基金Project(51479097)supported by the National Natural Science Foundation of ChinaProject(2013-KY-2)supported by State Key Laboratory of Hydroscience and Hydraulic Engineering,China
文摘The rigid body limit equilibrium method(RBLEM) and finite element method(FEM) are two widely used approaches for rock slope's stability analysis currently. RBLEM introduced plethoric assumptions; while traditional FEM relied on artificial factors when determining factor of safety(FOS) and sliding surfaces. Based on the definition of structure instability that an elasto-plastic structure is not stable if it is unable to satisfy simultaneously equilibrium condition, kinematical admissibility and constitutive equations under given external loads, deformation reinforcement theory(DRT) is developed. With this theory, plastic complementary energy(PCE) can be used to evaluate the overall stability of rock slope, and the unbalanced force beyond the yield surface could be the identification of local failure. Compared with traditional slope stability analysis approaches, the PCE norm curve to strength reduced factor is introduced and the unbalanced force is applied to the determination of key sliding surfaces and required reinforcement. Typical and important issues in rock slope stability are tested in TFINE(a three-dimensional nonlinear finite element program), which is further applied to several representatives of high rock slope's stability evaluation and reinforcement engineering practice in southwest of China.
文摘Objective： Detection of abdominal in- jury is a very important component in trauma management, so a precise assessment of liver and spleen injuries includ- ing their severity degree is necessary. There is a good case to believe that in emergency situations the radiologists＇ performance may profit from a systematic approach using established scoring systems. Score systems as the organ injury scale （OIS） drawn up by the American Association for the Surgery of Trauma are a valuable guidance for objec- tive trauma assessment. Aim of this study was to evaluate retrospectively whether a structured approach using the OIS may help improve trauma assessment. Methods： Fifty-three patients, 38 male and 15 female who underwent CT and laparotomy after abdominal trauma were included in this study. The laparotomy was performed by experienced surgeons with a minimum experience of 6 years. While the original CT reports were written by differ- ent radiologists with a minimum experience of 3 years, and then a radiologist with experience of 4 years reviewed the same original CT pictures, resulting in the structured report. Both the original and structured CT results on liver and spleen injuries were transferred into OIS grades. Finally, the initial and structured CT results were compared with theintraoperative findings gathered from the surgery report. Results： Regarding the original CT report we found a mean divergence of 0.68±0.8 （r=-0.45） to the OIS finding in the surgery report for liver injuries （0.69±1.17 for spleen injuries; r=-0.69）. In comparison with the structured approach, where we detected a divergence of 0.8±0.68; r=-0.63 （0.47±0.77 for spleen injuries; r=0.91）, there was no significant difference. However we detected a lower rate of over-diag- nosis in structured approaches. Conclusion： Our study shows that a structured ap- proach to triage abdominal trauma using an imaging check- list does not lead to a significantly higher detection rate, but a nonsignificant trend to reduce the rate of over- diagnoses, thus being more precise in grading the severity grade. Concerning the bias by retrospective study design, further prospective investigations are needed to evaluate the impact of trauma scores on the workflow in emergency department procedure as structured reporting systems are a valuable guidance in other radiological disciplines.
