Unmanned Aero Vehicles (UAV) has become a useful entity for quite a good number of industries and facilities. It is an agile, cost effective and reliable solution for communication, defense, security, delivery, survei...Unmanned Aero Vehicles (UAV) has become a useful entity for quite a good number of industries and facilities. It is an agile, cost effective and reliable solution for communication, defense, security, delivery, surveillance and surveying etc. However, their reliability is dependent on the resilient and stabilizes performance based on control systems embedded behind the body. Therefore, the UAV is majorly dependent upon controller design and the requirement of particular performance parameters. Nevertheless, in modern technologies there is always a room for improvement. In the similar manner a UAV lateral control system was implemented and researched in this study, which has been optimized using Proportional, Integral and Derivative (PID) controller, phase lead compensator and signal constraint controller. The significance of this study is the optimization of the existing UAV controller plant for improving lateral performance and stability. With this UAV community will benefit from designing robust controls using the optimized method utilized in this paper and moreover this will provide sophisticated control to operate in unpredictable environments. It is observed that results obtained for optimized lateral control dynamics using phase lead compensator (PLC) are efficacious than the simple PID feedback gains. However, for optimizing unwanted signals of lateral velocity, yaw rate, and yaw angle modes, PLC were integrated with PID to achieve dynamical stability.展开更多
Objective To study the activation changes of the brain in patients with amyotrophic lateral sclerosis （ALS） while executing sequential finger tapping movement using the method of blood oxygenation level dependent （...Objective To study the activation changes of the brain in patients with amyotrophic lateral sclerosis （ALS） while executing sequential finger tapping movement using the method of blood oxygenation level dependent （BOLD） functional magnetic resonance imaging （tMRI）. Methods Fifteen patients with definite or probable ALS and fifteen age and gender matched normal controls were enrolled. MRI was performed on a 3.0 Tesla scanner with standard headcoiL The functional images were acquired using a gradient echo single shot echo planar imaging （EPI） sequence. All patients and normal subjects executed sequential finger tapping movement at the frequency of 1-2 Hz during a block-design motor task. Structural MRI was acquired using a three-dimensional fast spoiled gradient echo （3D-FSPGR） sequence. The tMRI data were analyzed by statistical parametric mapping （SPM）. Results Bilateral primary sensorimotor cortex （ PSM）, bilateral premotor area （ PA）, bilateral supplementary motor area （SMA）, bilateral parietal region （ PAR）, contralateral inferior lateral premotor area （ ILPA）, and ipsilateral cerebellum showed activation in both ALS patients and normal controls when executing the same motor task. The activation areas in bilateral PSM, bilateral PA, bilateral SMA, and ipsilateral cerebellum were significantly larger in ALS patients than those in normal controls （ P 〈 0.05 ）. Extra activation areas including ipsilateral ILPA, bilateral posterior limb of internal capsule, and contralateral cerebellum were only detected in ALS patients. Conclusions Similar activation areas are activated in ALS patients and normal subjects while executing the same motor task. The increased activation areas in ALS patients may represent neural reorganization, while the extra activation areas in ALS patients may indicate functional compensation.展开更多
研制了一款基于In Ga As/Ga As P应变补偿量子阱结构的1 060 nm单横模半导体激光器,并采用金属有机物化学气相沉积（MOCVD）方法实现了外延生长。使用张应变的Ga As P势垒层对量子阱的应变进行补偿,并优化了MOCVD外延生长条件。所制备...研制了一款基于In Ga As/Ga As P应变补偿量子阱结构的1 060 nm单横模半导体激光器,并采用金属有机物化学气相沉积（MOCVD）方法实现了外延生长。使用张应变的Ga As P势垒层对量子阱的应变进行补偿,并优化了MOCVD外延生长条件。所制备的单横模激光器的脊宽为4μm,腔长为2 mm,25℃时测得其阈值电流为23 m A,最大斜率效率为1 W/A,直流电流为500 m A时光功率为437 mW。脉冲驱动时,器件最高输出功率达到1.2 W,并未发生腔面光学灾变损伤失效。器件快慢轴发散角分别为46.3°和7.4°,65℃时,器件的输出功率为270 mW。采用高温加速老化试验对器件的可靠性进行了评估,试验器件在3 150 h内未发生失效,功率缓慢退化速率为5×10-6h-1。展开更多
文摘Unmanned Aero Vehicles (UAV) has become a useful entity for quite a good number of industries and facilities. It is an agile, cost effective and reliable solution for communication, defense, security, delivery, surveillance and surveying etc. However, their reliability is dependent on the resilient and stabilizes performance based on control systems embedded behind the body. Therefore, the UAV is majorly dependent upon controller design and the requirement of particular performance parameters. Nevertheless, in modern technologies there is always a room for improvement. In the similar manner a UAV lateral control system was implemented and researched in this study, which has been optimized using Proportional, Integral and Derivative (PID) controller, phase lead compensator and signal constraint controller. The significance of this study is the optimization of the existing UAV controller plant for improving lateral performance and stability. With this UAV community will benefit from designing robust controls using the optimized method utilized in this paper and moreover this will provide sophisticated control to operate in unpredictable environments. It is observed that results obtained for optimized lateral control dynamics using phase lead compensator (PLC) are efficacious than the simple PID feedback gains. However, for optimizing unwanted signals of lateral velocity, yaw rate, and yaw angle modes, PLC were integrated with PID to achieve dynamical stability.
基金Supported by National Natural Sciences Foundation of China(30470512)
文摘Objective To study the activation changes of the brain in patients with amyotrophic lateral sclerosis （ALS） while executing sequential finger tapping movement using the method of blood oxygenation level dependent （BOLD） functional magnetic resonance imaging （tMRI）. Methods Fifteen patients with definite or probable ALS and fifteen age and gender matched normal controls were enrolled. MRI was performed on a 3.0 Tesla scanner with standard headcoiL The functional images were acquired using a gradient echo single shot echo planar imaging （EPI） sequence. All patients and normal subjects executed sequential finger tapping movement at the frequency of 1-2 Hz during a block-design motor task. Structural MRI was acquired using a three-dimensional fast spoiled gradient echo （3D-FSPGR） sequence. The tMRI data were analyzed by statistical parametric mapping （SPM）. Results Bilateral primary sensorimotor cortex （ PSM）, bilateral premotor area （ PA）, bilateral supplementary motor area （SMA）, bilateral parietal region （ PAR）, contralateral inferior lateral premotor area （ ILPA）, and ipsilateral cerebellum showed activation in both ALS patients and normal controls when executing the same motor task. The activation areas in bilateral PSM, bilateral PA, bilateral SMA, and ipsilateral cerebellum were significantly larger in ALS patients than those in normal controls （ P 〈 0.05 ）. Extra activation areas including ipsilateral ILPA, bilateral posterior limb of internal capsule, and contralateral cerebellum were only detected in ALS patients. Conclusions Similar activation areas are activated in ALS patients and normal subjects while executing the same motor task. The increased activation areas in ALS patients may represent neural reorganization, while the extra activation areas in ALS patients may indicate functional compensation.
文摘研制了一款基于In Ga As/Ga As P应变补偿量子阱结构的1 060 nm单横模半导体激光器,并采用金属有机物化学气相沉积（MOCVD）方法实现了外延生长。使用张应变的Ga As P势垒层对量子阱的应变进行补偿,并优化了MOCVD外延生长条件。所制备的单横模激光器的脊宽为4μm,腔长为2 mm,25℃时测得其阈值电流为23 m A,最大斜率效率为1 W/A,直流电流为500 m A时光功率为437 mW。脉冲驱动时,器件最高输出功率达到1.2 W,并未发生腔面光学灾变损伤失效。器件快慢轴发散角分别为46.3°和7.4°,65℃时,器件的输出功率为270 mW。采用高温加速老化试验对器件的可靠性进行了评估,试验器件在3 150 h内未发生失效,功率缓慢退化速率为5×10-6h-1。
