Viscous Vortex Particle Method Coupling with Computational Structural Dynamics for Rotor Comprehensive Analysis

A panel/vortex particle hybrid method is coupled with a computational structure dynamics code to predict helicopter rotor loads. The rotor blade surfaces and near wakes are modeled by the panel method, while the far wake is modeled by resorting to the vortex particles method. A fast summation method is introduced to accelerate the evolution of particle–particle-induced velocity and its derivative as well as panel–particle interactions. The developed vortex particle method code is coupled with the multibody code MBDyn to predict the rotor airloads. Numerical validations are carried, out and the results are compared with the experiments and simulation results in the literature.

A treecode based on barycentric Hermite interpolation for electrostatic particle interactions

A particle-cluster treecode based on barycentric Hermite interpolation is presented for fast summation of electrostatic particle interactions in 3D. The interpolation nodes are Chebyshev points of the 2nd kind in each cluster. It is noted that barycentric Hermite interpolation is scale-invariant in a certain sense that promotes the treecode’s efficiency. Numerical results for the Coulomb and screened Coulomb potentials show that the treecode run time scales like O(N log N), where N is the number of particles in the system. The advantage of the barycentric Hermite treecode is demonstrated in comparison with treecodes based on Taylor approximation and barycentric Lagrange interpolation.

An Asynchronous Summation Circuit for Noise Filtering in Single Photon Avalanche Diode Sensors

An asynchronous projection and summation circuit is proposed for single photon avalanche diode (SPAD) sensors. Thanks to the efficient interconnection by the asynchronous technique, the circuit can be easily implemented inside 2D SPAD arrays. As a result, the precise summation of the 1b data in one row can be parallel processed for all rows within the same cycle. A test-of-concept chip was fabricated in a 0.18[Formula: see text][Formula: see text]m 1P5M CMOS process. By measurement results, the summation of a 15-pixel row can be achieved by the proposed circuit within 20.5[Formula: see text]ns. Such a speed is very important for SPAD-based sensors that need fast summation operations.