The paper presents an improved equivalent circuit parameters extraction method for the dumbbell-shaped defected ground structure (DGS). The new extraction parameters equations are obtained in closed-form expressions, ...The paper presents an improved equivalent circuit parameters extraction method for the dumbbell-shaped defected ground structure (DGS). The new extraction parameters equations are obtained in closed-form expressions, which contain S11 and S21. The DGS unit with center frequency of 5 GHz is designed and fabricated on a TLX substrate with thickness of 1 mm and dielectric constant of 2.55. The circuit simulated results are in good agreement with the measured results. This parameters extraction method can be widely used for the design and analysis of DGS .展开更多
Background:Spinal dumbbell-shaped epidural cavernous malformation (CM) is a rare, hypervascular entity frequently misdiagnosed for other lesions, leading to unexpected intraoperative bleeding and suboptimal resection....Background:Spinal dumbbell-shaped epidural cavernous malformation (CM) is a rare, hypervascular entity frequently misdiagnosed for other lesions, leading to unexpected intraoperative bleeding and suboptimal resection. Our study aims to elucidate the demographics, management strategy, and outcome of this vascular disease.Methods:Retrospective review of patients seen in Beijing Tiantan Hospital with symptomatic dumbbell-shaped epidural CM from 2008 to 2013. All lesions were pathologically confirmed after resection. The clinical manifestations, radiographic features, and treatment modalities of these cases were analyzed.Results:We included 9 consecutive patients. Average age was 58 ± 12 years (range:34-79 years), with 66.7％male. Locations of the CMs were:thoracic (n=7, 77.8％), cervical (n=1, 11.1％), and cervicothoracic junction (n=1, 11.1％). Only one case presented with acute manifestations while others experienced chronic progressive spinal cord symptoms. The initial clinical diagnoses were:schwannoma (n=6, 66.7％), cavernous hemangioma (CM) (n=1, 11. 1％), meningioma (n=1, 11.1％), and angioma (n=1, 11.1％). Total resection was achieved in six patients (66.7％), and partial resection in the other three patients (33.3％). Average intraoperative blood loss was 400 ± 300 ml (range:100-1000 ml). During an average follow-up of 71 ± 21 months (range:29-94 months), excellent outcome was achieved in seven cases (77.8％), one partially improved (11.1％), and one deteriorated (11.1％). No patients experienced recurrence of symptoms.Conclusions:Spinal dumbbell-shaped epidural CM is a benign vascular malformation that should be differentiated from other dumbbell-shaped lesions. Accurate preoperative diagnose is challenging as no specific radiographic marker has been established. Total surgical resection should be recommended.展开更多
A kind of dual-band-stop filter with an unsymmetrical T-shape defected ground structure （DGS） is proposed. The filter has two band gap centers at 4.9 GHz and 7.35 GHz, respectively, where the two centre frequencies ...A kind of dual-band-stop filter with an unsymmetrical T-shape defected ground structure （DGS） is proposed. The filter has two band gap centers at 4.9 GHz and 7.35 GHz, respectively, where the two centre frequencies are just the second and third harmonics 2.45 GHz. The filters with high band-stop performance and wideband spurious suppression can be achieved by cascading miniaturized unsymmetrical T-shape DGS. The attenuation of three-cascaded T-shape DGS filter is 30.77 dB at 4.9 GHz and 17.96 dB at 7.35 GHz respectively. The above experimental results are in good agreement with the simulation results, especially for the third harmonic.展开更多
文摘The paper presents an improved equivalent circuit parameters extraction method for the dumbbell-shaped defected ground structure (DGS). The new extraction parameters equations are obtained in closed-form expressions, which contain S11 and S21. The DGS unit with center frequency of 5 GHz is designed and fabricated on a TLX substrate with thickness of 1 mm and dielectric constant of 2.55. The circuit simulated results are in good agreement with the measured results. This parameters extraction method can be widely used for the design and analysis of DGS .
文摘Background:Spinal dumbbell-shaped epidural cavernous malformation (CM) is a rare, hypervascular entity frequently misdiagnosed for other lesions, leading to unexpected intraoperative bleeding and suboptimal resection. Our study aims to elucidate the demographics, management strategy, and outcome of this vascular disease.Methods:Retrospective review of patients seen in Beijing Tiantan Hospital with symptomatic dumbbell-shaped epidural CM from 2008 to 2013. All lesions were pathologically confirmed after resection. The clinical manifestations, radiographic features, and treatment modalities of these cases were analyzed.Results:We included 9 consecutive patients. Average age was 58 ± 12 years (range:34-79 years), with 66.7％male. Locations of the CMs were:thoracic (n=7, 77.8％), cervical (n=1, 11.1％), and cervicothoracic junction (n=1, 11.1％). Only one case presented with acute manifestations while others experienced chronic progressive spinal cord symptoms. The initial clinical diagnoses were:schwannoma (n=6, 66.7％), cavernous hemangioma (CM) (n=1, 11. 1％), meningioma (n=1, 11.1％), and angioma (n=1, 11.1％). Total resection was achieved in six patients (66.7％), and partial resection in the other three patients (33.3％). Average intraoperative blood loss was 400 ± 300 ml (range:100-1000 ml). During an average follow-up of 71 ± 21 months (range:29-94 months), excellent outcome was achieved in seven cases (77.8％), one partially improved (11.1％), and one deteriorated (11.1％). No patients experienced recurrence of symptoms.Conclusions:Spinal dumbbell-shaped epidural CM is a benign vascular malformation that should be differentiated from other dumbbell-shaped lesions. Accurate preoperative diagnose is challenging as no specific radiographic marker has been established. Total surgical resection should be recommended.
基金supported by the National Natural Science Foundation of China (61171051, 61202399, 61072136)
文摘A kind of dual-band-stop filter with an unsymmetrical T-shape defected ground structure （DGS） is proposed. The filter has two band gap centers at 4.9 GHz and 7.35 GHz, respectively, where the two centre frequencies are just the second and third harmonics 2.45 GHz. The filters with high band-stop performance and wideband spurious suppression can be achieved by cascading miniaturized unsymmetrical T-shape DGS. The attenuation of three-cascaded T-shape DGS filter is 30.77 dB at 4.9 GHz and 17.96 dB at 7.35 GHz respectively. The above experimental results are in good agreement with the simulation results, especially for the third harmonic.
