Steady-state visual evoked response (SSVEP) is widely used in visual-based diagnosis and applications such as brain–computer interfacing due to its high information transfer rate and the capability to activate commands through simple gaze control. However, one major impediment in using flashing visual stimulus to obtain SSVEP is eye fatigue that prevents continued long-term use preventing practical deployment. This combined with the difficulty in establishing precise pulse-width modulation (PWM) that results in poorer accuracy warrants the development of appropriate approach to solve these issues. Various studies have suggested the usage of high frequencies of visual stimulus to reduce the visual fatigue for the user but this results in poor response performance. Here, the authors study the use of extremely high duty-cycles in the stimulus in the hope of solving these constraints. Electroencephalogram data was recorded with PWM duty-cycles of 50–95% generated by a precise custom-made light-emitting diode hardware and tested ten subjects responded that increasing duty-cycles had less visual strain for all the frequency values and the SSVEP exhibited a subject-independent peak response for duty-cycle of 85%. This could pave the way for increased usage of SSVEP for practical applications.

A maximum torque/ampere (MTPA) interior permanent magnet synchronous motor (IPMSM) drive system that does not require a high-frequency sinusoidal generator is proposed. By using a band-pass filter, the high-frequency variation of the output mechanical power, which is proportional to the slope of torque to advance angle, can be obtained. After that, the high-frequency variation of the output mechanical power and the amplitude of the stator current vector are inputted into a fuzzy-logic controller. By using the fuzzy-logic controller, the advance angle of the MTPA for an IPMSM can be automatically determined. In addition, an adaptive speed controller is designed to improve the transient responses, load disturbance responses, and tracking responses of the closed-loop MTPA drive system. A digital signal processor, TMS-320LF-2812, is used as the control centre to execute the adaptive speed controller and the MTPA searching algorithm. Experimental results validate the correctness and feasibility of the proposed method. The proposed drive system can be applied for air conditioners, adjustable speed fans, and other industry drives.

Owing to efficient query processing for random workload, the hybrid crack sort (HCS) has become an important adaptive indexing approach in main-memory column store. However, under sequential workload scenarios, the HCS does not obtain a good query execution performance, because of great reorganisation overhead imposed on the initial queries. The authors propose a hybrid radix crack sort (HRCS) approach to solve this problem. By the adoption of radix-based partition strategy, it divides the unsorted column into disjoint key ranges and then conducts data reorganisation in at most two key ranges for each query. For HRCS, only a small portion of the whole column needs to be touched for the processing of each query, thus reducing the reorganisation cost and improving the query execution performance. The final experiments show that the novel HRCS approach can obtain a higher query execution performance for not only random workload but also sequential workload, as compared with HCS.

A three-dimensional (3D) signal sparse representation (SR) model that can be used for joint Doppler frequency, direction of departure and direction of arrival estimation in bistatic multiple-input–multiple-output radar is built. Then, a fast 3D orthogonal matching pursuit (OMP) algorithm is put forward to estimate the 3D parameters. First, the problem of targets 3D parameters joint estimation is decomposed into three estimation problems whose computation burden is decreased. Then, the high-resolution 3D parameters of all targets are got by solving a very small-scale SR problem. Numerical simulations verify that the proposed algorithm can get similar estimation accuracy and decrease the computational burden compared with the traditional 1D OMP algorithm.