When faced with a specific optimization problem, deciding which algorithm to apply is always a difficult task. Not only is there a vast variety of algorithms to select from, but these algorithms are often controlled by many hyperparameters, which need to be suitably tuned in order to achieve peak performance. Usually, the problem of selecting and configuring the optimization algorithm is addressed sequentially, by first selecting a suitable algorithm and then tuning it for the application at hand. Integrated approaches, commonly known as Combined Algorithm Selection and Hyperparameter (CASH) solvers, have shown promise in several applications. In this work we compare sequential and integrated approaches for selecting and tuning the best out of the 4,608 variants of the modular Covariance Matrix Adaptation Evolution Strategy (CMA-ES). We show that the ranking of these variants depends to a large extent on the quality of the hyperparameters. Sequential approaches are therefore likely to recommend sub-optimal choices. Integrated approaches, in contrast, manage to provide competitive results at much smaller computational cost. We also highlight important differences in the search behavior of two CASH approaches, which build on racing (irace) and on model-based optimization (MIP-EGO), respectively.

Aiming at the problem of terminal position estimation under Internet of vehicles environment, the paper proposes a Vibrio Foraging Optimization (VFO) positioning algorithm assisted by multiple Reconfigurable Intelligent Surfaces (RISs). The system model for multiple RISs aided positioning under Internet of vehicles environment is first constructed. To achieve the goal of reducing system implementation complexity, the method of exploiting a single transmitting end node to construct virtual anchor nodes for target positioning is adopted. The proposed VFO algorithm is applied to solve the positioning objective function constructed by geometric relations to obtain the estimated position of the target vehicle. Additionally, the Direction of Arrival (DOA) parameter is introduced and matrix reconstructed estimation of signal parameters by rotational invariance technique (MR-ESPRIT) algorithm is employed for reducing the computational complexity and further improving the performance of the positioning algorithm. Simulation results further demonstrate that the proposed VFO algorithm based on multiple RISs can achieve better positioning performance with relatively low system complexity.

The matrix decomposition (MD) based FIR filter design technique can synthesize a traditional FIR filter with much less implementation complexity. A scheme for obtaining more sparse coefficients of a MD-FIR filter is proposed, which consists of two parts. The first part is the previous procedure of designing a MD-FIR filter (i.e., design an initial MD-FIR filter using a certain MD method and optimize its coefficients). The second part is the proposed procedure of obtaining more sparse coefficients, where the MD-FIR filters' coefficients also need to be optimized. The performances of the various initial MD-FIR filters, which are obtained based on the various MD methods, in the implementation of this scheme are experimentally compared. The MD-FIR filter's coefficients can be effectively optimized by the trust-region iterative-gradient-searching (TR-IGS) algorithm. We present further results on the TR-IGS. The error bound for each iteration of TR-IGS is analyzed. A convergent online implementation scheme of the TR-IGS is presented and analyzed theoretically and experimentally. The proof of the convergence is provided. A sufficient condition for determining whether a theoretical termination point of the scheme is a strict local optimum point is provided. The step-size optimization problem for the TR-IGS is analyzed theoretically and experimentally.