The methodology of catchment extraction especially from regular grid digital elevation models (DEMs) is briefly reviewed. Then an efficient algorithm, which combines vector process and traditional neighbourhood raster...The methodology of catchment extraction especially from regular grid digital elevation models (DEMs) is briefly reviewed. Then an efficient algorithm, which combines vector process and traditional neighbourhood raster process, is designed for extracting the catchments and subcatchments from depressionless DEMs. The catchment area of each river in the grid DEM data is identified and delineated, then is divided into subcatchments as required. Compared to traditional processes, this method for identifying catchments focuses on the boundaries instead of the area inside the catchments and avoids the boundary intersection phenomena. Last, the algorithm is tested with a set of DEMs of different sizes, and the result proves that the computation efficiency and accuracy are better than existent methods.展开更多
To investigate the influence of hip a nd pelvic fracture, especially acetabular fracture complicated by sciatic nerve injury on clinical features and prognosis of sciatic nerve injury. Methods: From January 1987 to Ja...To investigate the influence of hip a nd pelvic fracture, especially acetabular fracture complicated by sciatic nerve injury on clinical features and prognosis of sciatic nerve injury. Methods: From January 1987 to January 2000, 17 patients (14 mal e and 3 female) who had hip and pelvic fractures complicated by sciatic nerve in jury were treated with operative reduction and internal fixation and followed up from 10 months to 5 years. The average age was 38 years (ranging 23 56 years). The left extremities were involved in 11 patients and the right in 6. Twelve pa tients underwent primary exploration and neurolysis and 5 patients underwent sec ondary operation. Results: Preoperatively, 8 patients were treated with large dos es of oral narcotics to control their severe sciatic pain. Three of the 8 patien ts underwent patient controlled analgesia and epidural analgesia. After operati on, excellent and good rates of reduction and functional recovery of sciatic ner ve were 94.1 % and 88% respectively. Four patients still had sciatic pain and 2 patients failed to recover. Sciatic nerve function improved within 3 6 month s after surgery in 11 patients. Conclusions: Hip and pelvic fractures can result in sciatic ner ve injury, especially common peroneal nerve injury and prognosis is poor. Open r eduction and internal fixation combined with nerve exploration and neurolysis sh ould be used as early as possible for severe sciatic pain.展开更多
文摘The methodology of catchment extraction especially from regular grid digital elevation models (DEMs) is briefly reviewed. Then an efficient algorithm, which combines vector process and traditional neighbourhood raster process, is designed for extracting the catchments and subcatchments from depressionless DEMs. The catchment area of each river in the grid DEM data is identified and delineated, then is divided into subcatchments as required. Compared to traditional processes, this method for identifying catchments focuses on the boundaries instead of the area inside the catchments and avoids the boundary intersection phenomena. Last, the algorithm is tested with a set of DEMs of different sizes, and the result proves that the computation efficiency and accuracy are better than existent methods.
文摘To investigate the influence of hip a nd pelvic fracture, especially acetabular fracture complicated by sciatic nerve injury on clinical features and prognosis of sciatic nerve injury. Methods: From January 1987 to January 2000, 17 patients (14 mal e and 3 female) who had hip and pelvic fractures complicated by sciatic nerve in jury were treated with operative reduction and internal fixation and followed up from 10 months to 5 years. The average age was 38 years (ranging 23 56 years). The left extremities were involved in 11 patients and the right in 6. Twelve pa tients underwent primary exploration and neurolysis and 5 patients underwent sec ondary operation. Results: Preoperatively, 8 patients were treated with large dos es of oral narcotics to control their severe sciatic pain. Three of the 8 patien ts underwent patient controlled analgesia and epidural analgesia. After operati on, excellent and good rates of reduction and functional recovery of sciatic ner ve were 94.1 % and 88% respectively. Four patients still had sciatic pain and 2 patients failed to recover. Sciatic nerve function improved within 3 6 month s after surgery in 11 patients. Conclusions: Hip and pelvic fractures can result in sciatic ner ve injury, especially common peroneal nerve injury and prognosis is poor. Open r eduction and internal fixation combined with nerve exploration and neurolysis sh ould be used as early as possible for severe sciatic pain.
