Search

Accessing to the optimal network was an effective way of ensuring the efficiency of network resources utilization and improving network performance.An access point selection mechanism based on cross-layer awareness for cognitive networks(CN_CLA)was proposed.Firstly,a cross-layer cognitive framework was constructed for obtaining the primary evaluation parameters that influence the performance of network access.Secondly,the fuzzy theory was applied for evaluating the access network performance comprehensively,and the weights in each layer were optimized using the quantum genetic algorithm,and then the access point was selected intelligently.Simulation results show that the proposed method chooses reasonable access networks without intervention of users.Furthermore,it is superior to the traditional methods,including the link capacity scheme,H_RSSI_S and AS_FTM,in terms of throughput,delay,session completion rate,packet loss and other performance indicators.

Due to the detection sensitivity provided by the high nuclear spin polarization, hyperpolarized 129Xe has been employed in animal and human magnetic resonance imaging (MRI). However, during the accumulation-thawing process of hyperpolarized 129Xe, multiple factors lead to the relaxation of spin polarization and would hinder the wider application of 129Xe. In this research, the spin relaxation mechanism of hyperpolarized 129Xe during the accumulation-thawing process is investigated by both theoretical model analysis and experimental measurements. Meanwhile, the stability of the homebuilt device for the accumulation-thawing is measured. Our results demonstrate that the thawing mode and the cold trap material significantly affect the polarization loss; the automatic device is very stable during long-term operation and shows a high degree of automation, resulting in a polarization recovery ratio of 85.6% ± 4.7%. This research greatly helps to improve the efficiency of hyperpolarized 129Xe in animal and human MRI.

Objective: To investigate the clinical features of children with incomplete Kawasaki disease (IKD), and to provide reference for the early diagnosis of IKD., Methods: The clinical data of 22 hospitalized children with IKD were analyzed retrospectively and compared with the data of 63 children with Kawasaki disease (KD) who were hospitalized during the same period of time. Another 20 children with pyrexia were enrolled as the control group., Results: Pyrexia was observed in all children. Compared with the KD group, the IKD group had significantly lower proportions of children with changes in the limbs, conjunctival hyperaemia, and cervical lymphadenectasis (P<0.05), a significantly higher serum level of glutamic-pyruvic transaminase (P<0.05), and significantly lower levels of plasma albumin, serum sodium, and interleukin-6 (P<0.05). There was no significant difference in the rate of γ-globulin application between the IKD and KD groups; however, the IKD group had a significantly higher incidence rate of coronary artery lesion than the KD group (P<0.05)., Conclusions: The symptoms and signs in children with IKD are untypical. The liver function test and serum hyponatremia and IL-6 measurements may be useful for the diagnosis of IKD.