Reasonable and effective allocation of cognitive radio spectrum resource according to user’s requirements is the key task of cognitive radio network. Cognitive radio spectrum allocation problem can be viewed as an optimization problem. This paper analyzes the application of bio-inspired intelligent algorithm in cognitive radio network spectrum allocation, and based on graph theory model of spectrum allocation, proposesaspectrum allocation algorithm based on autonomously evolutionary scheme. Three objective functions: Max-Min-Reward, Max-Sum- Reward and Max-Proportional-Fair are employed to evaluate the proposed algorithm capacity. The simulation result reveals that the proposed method can make the system user to obtain better network benefits and better embody the fairness between cognitive users. In the process of allocation, the proposed method was not restricted by user scale and the number of spectrums.
The clinical value of combined use of MR imaging and multi-slice spiral CT in limb salvage surgery for orthopaedic oncology patients: initial experience in nine patients
Background. The purpose of this prospective study was to evaluate the value of the combined use of MR imaging and multi-slice spiral CT for limb salvage surgery in orthopaedic oncology patients.
Patients and methods. Nine consecutive patients with lower/upper limb malignant bone tumours (7 osteosarcomas and 2 chondrosarcomas) were treated with limb-salvaging procedures. Preoperative planning including determination of the osteotomy plane and diameters of the prosthesis was performed basing on the preoperative CT and MR images. The histopathology was performed as golden diagnostic criteria to evaluate the accuracy of CT and MR-based determination for tumour's boundary.
Results. The tumour extension measured on MRI was consistent with the actual extension (P>0.05, paired Student's t test), while the extension measured on CT imaging was less than the actual extension. The length, offset and alignment of the affected limb were reconstructed accurately after the operation. An excellent functional outcome was achieved in all patients.
Conclusions. In the present study, MRI was found to be superior to CT for determining the tumour extension, combined use of MRI and CT measurement provided high precision for the fit of the prosthesis and excellent functional results.