Broadband microwave absorption properties of polyurethane foam absorber optimized by sandwiched cross-shaped metamaterial

The effect of a sandwiched cross-shaped metamaterial absorber(CMMA) on microwave absorption properties of the double-layered polyurethane foam absorber(PUFA) is investigated. Combining with the sandwiched CMMA, the bandwidth of -10-dB reflection loss for PUFA is broadened from 7.4 GHz to 9.1 GHz, which is attributed to the overlap of two absorption peaks originating from CMMA and PUFA, respectively. The values of the two absorption peaks located at 10.15 GHz and 14.7 GHz are -38.44 dB and -40.91 dB, respectively. Additionally, distribution of surface current,electromagnetic field and power loss density are introduced to investigate the absorption mechanism of the CMMA. The electromagnetic field distribution of the double-layered PUFA and the three-layered hybrid absorber are comparatively analyzed to ascertain the influence of CMMA. The results show that the proposed hybrid absorber can be applied to the anti-electromagnetic interference and stealth technology.

Surface potential-based analytical model for InGaZnO thin-film transistors with independent dual-gates

An analytical drain current model on the basis of the surface potential is proposed for indium-gallium zinc oxide(InGaZnO)thin-film transistors(TFTs)with an independent dual-gate(IDG)structure.For a unified expression of carriers’distribution for the sub-threshold region and the conduction region,the concept of equivalent flat-band voltage and the Lambert W function are introduced to solve the Poisson equation,and to derive the potential distribution of the active layer.In addition,the regional integration approach is used to develop a compact analytical current-voltage model.Although only two fitting parameters are required,a good agreement is obtained between the calculated results by the proposed model and the simulation results by TCAD.The proposed current-voltage model is then implemented by using Verilog-A for SPICE simulations of a dual-gate InGaZnO TFT integrated inverter circuit.

Relationship between postoperative complications and fibular integrity in congenital pseudarthrosis of the tibia in children

Background:This study aimed to investigate the relationship between postoperative complications and fibular integrity in congenital pseudarthrosis of the tibia (CPT) in children.Methods:A retrospective study was performed in 59 patients with Crawford type Ⅳ CPT who were treated with combined surgical technique from 2007 to 2011.The patients were divided into two groups,the CPT with fibular pseudarthrosis (group A) and CPT with intact fibula groups (group B),on the basis of fibula status after the union of CPT.The incidence rates of refracture,ankle vaigus,tibial valgus,and limb length discrepancy in the two groups were investigated.Results:In group A,14 (36.8%) cases had refracture,30 (78.9%) had ankle valgus;27 (71%) exhibited tibial valgus with an average tibial valgus of 7 (6-20),and 24 (63.2%) had limb length discrepancy with an average limb length of 1.26 cm (0.6-4.4 cm).In group B,2 (9.5%) cases had refracture,11 (52.4%) had ankle valgns,8 (42.9%) had tibial valgus with an average tibial valgus deformity of 2.9 (6-13),and 13 (61.9%) had limb length discrepancy with an average limb length of 1.48 cm (0.5-5 cm).Significant difference in refracture and ankle valgus was found between groups A and B (P<0.05).Conclusions:After the union of CPT,patients with fibular pseudarthrosis showed higher incidence of refracture and ankle valgus than those with intact fibula.Attention should be paid to the presence of fibular pseudarthrosis when managing CPT.