Robust optimization model and algorithm for railway freight center location problem in uncertain environment.

Railway freight center location problem is an important issue in railway freight transport programming. This paper focuses on the railway freight center location problem in uncertain environment. Seeing that the expected value model ignores the negative influence of disadvantageous scenarios, a robust optimization model was proposed. The robust optimization model takes expected cost and deviation value of the scenarios as the objective. A cloud adaptive clonal selection algorithm (C-ACSA) was presented. It combines adaptive clonal selection algorithm with Cloud Model which can improve the convergence rate. Design of the code and progress of the algorithm were proposed. Result of the example demonstrates the model and algorithm are effective. Compared with the expected value cases, the amount of disadvantageous scenarios in robust model reduces from 163 to 21, which prove the result of robust model is more reliable.

Therapeutic effect of minimally invasive decompression combined with impaction bone grafting on osteonecrosis of the femoral head.

The aim of this study was to observe the therapeutic effect of minimally invasive decompression combined with impaction bone grafting on osteonecrosis of the femoral head. A total of 67 patients underwent minimally invasive lightbulb decompression combined with impaction bone grafting. The therapeutic effect was evaluated according to Harris scores, and fluoroscopic and magnetic resolution imaging results at different time points. The Harris score was significantly increased after operation. The fineness rate was 85.4%. Postoperative disease progression was found in nine patients with the progression rate of 14.63%. The average necrotic area percentage was noticeably reduced 6 months, 1 year, and 2 years after operation. The one-year postoperative percentage showed a significant difference compared with the preoperative one. Minimally invasive lightbulb decompression combined with impaction bone grafting can achieve a satisfactory curative effect on ONFH. This method has the advantages of small trauma, thorough decompression, and good bone implantation.

[Treatment of degenerative lumbar spondylolisthesis through posterolateral fusion and fixation with pedicle screws].

OBJECTIVE: To explore internal fixation whether can improve the clinical outcomes of decompression and posterolateral fusion in patients with degenerative lumbar spondylolisthesis. METHODS: From December 1998 to December 2005, 49 patients who had degenerative lumbar spondylolisthesis underwent decompression and posterolateral fusion without (group A, 21 cases) or with (group B, 28 cases) internal fixation (CD HORIZON M8 system). There were 12 males and 37 females with a mean age of 58.5 years (range, from 49 to 68 years). Among them,32 cases were grade I and 17 were grade II according to Meyerding grade system. All patients were followed up with an average of 58 months (range from 12 to 90 months). The pain of low back and leg (VAS scoring), spinal active function and neurologic function were evaluated according the assessment system of Yuan. RESULTS: The VAS score of low back in group A and B were respectively 41.9 +/- 7.5 and 32.8 +/- 6.2 at follow-up; and VAS score of leg in group A and B were respectively 33.9 +/- 7.3 and 30.8 +/- 6.2. Spinal active function of patients, 15 cases obtained improvement, 6 cases aggravation or no improvement in group A; 25 cases obtained improvement, 3 cases aggravation or no improvement in group B. Neurologic function of patients, 15 cases obtained improvement, 6 cases aggravation or no improvement in group A; 26 cases obtained improvement, 2 cases aggravation or no improvement in group B. The group B was better than group A in the aspect of low back pain, spine active function and neurologic function (P < 0.05). There was no statistically significant difference in improvement of leg pain between two groups (P > 0.05). CONCLUSION: Using internal fixation in decompression and posterolateral fusion for degenerative lumbar spondylolisthesis can improve low back pain and clinical function. Decompression is necessary for the surgical treatment of degenerative spondylolisthesis, which is major effect on the improvement of leg pain.