针对零中频接收机的卫星通信应用,文中首次将频域移位平均周期图法应用于零中频接收机,利用该算法工作信噪比低、估计范围大的优点,扩展了零中频接收机的载波捕获范围,并对算法中补零倍数的定义进行了修改。仿真结果表明,在信噪比大于2 ...针对零中频接收机的卫星通信应用,文中首次将频域移位平均周期图法应用于零中频接收机,利用该算法工作信噪比低、估计范围大的优点,扩展了零中频接收机的载波捕获范围,并对算法中补零倍数的定义进行了修改。仿真结果表明,在信噪比大于2 d B,经典高动态模型的通信环境中该算法可使接收机达到90%捕获概率,且捕获时间不大于1.2 s。展开更多
Purpose： The purpose of this study was to determine the extent that a static stretching program could increase heart rate （HR） and oxygen consumption （VO2）, and if the increases were sufficient to serve as a warm...Purpose： The purpose of this study was to determine the extent that a static stretching program could increase heart rate （HR） and oxygen consumption （VO2）, and if the increases were sufficient to serve as a warm-up for aerobic activity. Methods： The HR and VO2 of 15 male and 16 female college students were measured after either 12 min of passive static stretching （SS）, or 12 rain pseudo-stretching （PS）, which consisted of moving through the stretching positions without placing the muscles on stretch. Four different lower body stretches were used with each stretch held for 30 s before the participant moved to a different position, with the circuit being repeated four times. VO2 was determined by averaging breath-by-breath measures over the total 12 min. HR was obtained every 30 s and the 24 values were averaged. Warm-up benefit was determined from the 02 deficit accrued during 7-min cycling at 60% VOzmax. Results： HR （beats/rain, mean 4. SD） for SS （84 ± 11） was a significant （p 〈 0.05） 9% greater than PS （78 ± 12）. Similarly, VO2 （mL/min, mean 4. SD） for SS （0.53 ± 0.13） was a significant 44% greater than PS （0.38 ± 0.11）. The O2 deficit （L, mean 4, SD） for SS （0.64 ± 1.54） was not different from PS （0.72 ± 1.61）. Conclusion： These data indicate that passive static stretching increases both HR and VO2, indicating that metabolic activity can be increased without muscle activation. The magnitude of the increases, however, is not sufficient to elicit a warm-up effect.展开更多
A method, which can predict the valence band offsets at strained layer heterojunctions under different strain situations only by calculating band structures and deformation parameters of the bulk materials, is suggest...A method, which can predict the valence band offsets at strained layer heterojunctions under different strain situations only by calculating band structures and deformation parameters of the bulk materials, is suggested. The applicability of this method is verified by calculation of the valence band offsets at strained layer heterojuntions ,such as InP/InAs, InP/GaP, GaAs/InAs, GaP/GaAs and AlAs/InAs with various strain conditions.展开更多
Objective：Debate continues regarding the management of calcaneal fractures,between open reduction and internal fixation and closed treatment.Hence we aim at evaluating the radiological and functional outcomes of open...Objective：Debate continues regarding the management of calcaneal fractures,between open reduction and internal fixation and closed treatment.Hence we aim at evaluating the radiological and functional outcomes of open reduction and internal fixation in displaced joint depression type of calcaneal fractures fixed with locking calcaneal plate.Methods：In this series,28 patients （26 unilateral and 2 bilateral） with joint depression type of calcaneal fractures as per Essex-Lopresti classification system were operated on with locking calcaneal plate within 3 weeks of injury.Patients were evaluated in terms of associated injuries and X-rays of anteroposterior,lateral and axial views of the calcaneum.CT scan was done to assess the amount ofcomminution and articular depression.Patients were followed up clinically and radiologically at least for 1 year.Radiological assessment was done by Bohler＇s angle and Gissane＇s angle along with measurement ofcalcaneal height and width.Functional outcome was assessed using the American Orthopaedics Foot and Ankle Society （AOFAS） scale.Results：At average follow-up of 14.5 months,average AOFAS score was 86.3 （range 66 to 97）,with 86% having excellent to good results and 2 （7.7%） and 1 （3.7%） having fair and poor results respectively.All patients had stable ankle joint with all having dorsiflexion and plantar flexion more than 30°.Average subtalar range of motion was 17°.The mean Bohler＇s angle,mean Gissane＇s angle,calcaneal height and width were 25.47°,121.3°,4.32 cm and 3.81cm respectively at final follow-up.Three patients had flap necrosis at incision site and one had superficial and deep infection.Subtalar arthritis was seen in 5 patients,whereas sural nerve hypoaesthesia in 1 patient.None of the patients had compartment syndrome,heel pad problems,peroneal tendinitis,reflex sympathetic dystropy or implant failure.Conclusion：Open reduction and internal fixation with locking calcaneal plate gives sound functional outcome,i.e.restoring anatomically reconstruction of height,width,Bohler＇s and Gissiane＇s angles of the calcaneum,and allowing early mobilization.展开更多
A strain smoothing formulation for NURBS (non-uniform rational B-splines) based isogeometric finite element analysis is presented. This approach is formulated within the framework of assumed strain methods and strain ...A strain smoothing formulation for NURBS (non-uniform rational B-splines) based isogeometric finite element analysis is presented. This approach is formulated within the framework of assumed strain methods and strain smoothing operations. The strain smoothing is defined through strain averaging in the element sub-domains which are subsequently used for numerical integration of the Galerkin weak form. This formulation satisfies the orthogonality condition of the assumed strain methods. Meanwhile the present formulation totally avoids the gradient computation of the rational NURBS basis functions in the formulation of stiffness matrix. A transformation method is employed to accurately enforce the displacement boundary conditions. Numerical results demonstrate that the present formation gives very satisfactory solution accuracy simultaneously with improved computational efficiency.展开更多
文摘针对零中频接收机的卫星通信应用,文中首次将频域移位平均周期图法应用于零中频接收机,利用该算法工作信噪比低、估计范围大的优点,扩展了零中频接收机的载波捕获范围,并对算法中补零倍数的定义进行了修改。仿真结果表明,在信噪比大于2 d B,经典高动态模型的通信环境中该算法可使接收机达到90%捕获概率,且捕获时间不大于1.2 s。
文摘Purpose： The purpose of this study was to determine the extent that a static stretching program could increase heart rate （HR） and oxygen consumption （VO2）, and if the increases were sufficient to serve as a warm-up for aerobic activity. Methods： The HR and VO2 of 15 male and 16 female college students were measured after either 12 min of passive static stretching （SS）, or 12 rain pseudo-stretching （PS）, which consisted of moving through the stretching positions without placing the muscles on stretch. Four different lower body stretches were used with each stretch held for 30 s before the participant moved to a different position, with the circuit being repeated four times. VO2 was determined by averaging breath-by-breath measures over the total 12 min. HR was obtained every 30 s and the 24 values were averaged. Warm-up benefit was determined from the 02 deficit accrued during 7-min cycling at 60% VOzmax. Results： HR （beats/rain, mean 4. SD） for SS （84 ± 11） was a significant （p 〈 0.05） 9% greater than PS （78 ± 12）. Similarly, VO2 （mL/min, mean 4. SD） for SS （0.53 ± 0.13） was a significant 44% greater than PS （0.38 ± 0.11）. The O2 deficit （L, mean 4, SD） for SS （0.64 ± 1.54） was not different from PS （0.72 ± 1.61）. Conclusion： These data indicate that passive static stretching increases both HR and VO2, indicating that metabolic activity can be increased without muscle activation. The magnitude of the increases, however, is not sufficient to elicit a warm-up effect.
文摘A method, which can predict the valence band offsets at strained layer heterojunctions under different strain situations only by calculating band structures and deformation parameters of the bulk materials, is suggested. The applicability of this method is verified by calculation of the valence band offsets at strained layer heterojuntions ,such as InP/InAs, InP/GaP, GaAs/InAs, GaP/GaAs and AlAs/InAs with various strain conditions.
文摘Objective：Debate continues regarding the management of calcaneal fractures,between open reduction and internal fixation and closed treatment.Hence we aim at evaluating the radiological and functional outcomes of open reduction and internal fixation in displaced joint depression type of calcaneal fractures fixed with locking calcaneal plate.Methods：In this series,28 patients （26 unilateral and 2 bilateral） with joint depression type of calcaneal fractures as per Essex-Lopresti classification system were operated on with locking calcaneal plate within 3 weeks of injury.Patients were evaluated in terms of associated injuries and X-rays of anteroposterior,lateral and axial views of the calcaneum.CT scan was done to assess the amount ofcomminution and articular depression.Patients were followed up clinically and radiologically at least for 1 year.Radiological assessment was done by Bohler＇s angle and Gissane＇s angle along with measurement ofcalcaneal height and width.Functional outcome was assessed using the American Orthopaedics Foot and Ankle Society （AOFAS） scale.Results：At average follow-up of 14.5 months,average AOFAS score was 86.3 （range 66 to 97）,with 86% having excellent to good results and 2 （7.7%） and 1 （3.7%） having fair and poor results respectively.All patients had stable ankle joint with all having dorsiflexion and plantar flexion more than 30°.Average subtalar range of motion was 17°.The mean Bohler＇s angle,mean Gissane＇s angle,calcaneal height and width were 25.47°,121.3°,4.32 cm and 3.81cm respectively at final follow-up.Three patients had flap necrosis at incision site and one had superficial and deep infection.Subtalar arthritis was seen in 5 patients,whereas sural nerve hypoaesthesia in 1 patient.None of the patients had compartment syndrome,heel pad problems,peroneal tendinitis,reflex sympathetic dystropy or implant failure.Conclusion：Open reduction and internal fixation with locking calcaneal plate gives sound functional outcome,i.e.restoring anatomically reconstruction of height,width,Bohler＇s and Gissiane＇s angles of the calcaneum,and allowing early mobilization.
基金supported by the National Natural Science Foundation of China (Grant No. 10972188)the Program for New Century Excellent Talents in University from China Ministry of Education (Grant No. NCET-09-0678)the Fundamental Research Funds for the Central Universities of China (Grant No. 2010121073)
文摘A strain smoothing formulation for NURBS (non-uniform rational B-splines) based isogeometric finite element analysis is presented. This approach is formulated within the framework of assumed strain methods and strain smoothing operations. The strain smoothing is defined through strain averaging in the element sub-domains which are subsequently used for numerical integration of the Galerkin weak form. This formulation satisfies the orthogonality condition of the assumed strain methods. Meanwhile the present formulation totally avoids the gradient computation of the rational NURBS basis functions in the formulation of stiffness matrix. A transformation method is employed to accurately enforce the displacement boundary conditions. Numerical results demonstrate that the present formation gives very satisfactory solution accuracy simultaneously with improved computational efficiency.
