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D2D communication is a promising technology for enhancing spectral efficiency (SE) in cellular networks, and full-duplex (FD) has the potential to double SE. Due to D2D's short-distance communication and low transmittance power, it is natural to integrate FD into D2D, creating FD-D2D to underlay a cellular network to further improve SE. However, the residual self-interference (RSI) resulting from FD-D2D and interference arising from spectrum sharing between D2D users (DUs) and cellular users (CUs) can restrict D2D link performance. Therefore, we propose an FD-D2D underlying cellular system in which DUs jointly share uplink and downlink spectral resources with CUs. Moreover, we present two algorithms to enhance the performance experience of DUs while improving the system's SE. For the first algorithm, we tackle an optimization problem aimed at maximizing the sum rate of FD-DUs in the system while adhering to transmittance power constraints. This problem is formulated as a mixed-integer nonlinear programming problem (MINLP), known for its mathematical complexity and NP-hard nature. In order to address this MINLP, our first algorithm decomposes it into two subproblems: power control and spectral resource allocation. The power control aspect is treated as a nonlinear problem, which we solve through one-dimensional searching. Meanwhile, spectral resource allocation is achieved using the Kuhn–Munkres algorithm, determining the pairing of CUs and DUs sharing the same spectrum. As for the second algorithm, our objective is to enhance the individual performance of FD-DUs by maximizing the minimum rate among them, ensuring more uniform rate performance across all FD-DUs. In order to solve this optimization problem, we propose a novel spectral resource allocation algorithm based on bisection searching and the Kuhn–Munkres algorithm, whereas the power control aspect remains the same as in the first algorithm. The numerical results demonstrate that our proposed algorithm effectively enhances the performance of DUs in an FD-D2D underlying cellular network when compared to the sum rate maximization design. [ABSTRACT FROM AUTHOR]

Many ideas exist for the development of shock-capturing schemes, such as Roe, Harten–Lax–van Leer (HLL) and advection upstream splitting method (AUSM) families, and their extension for all-speed flow. A uniform algorithm that expresses the three families in the same framework is proposed in this study. The algorithm has an explicit physical meaning, provides new understanding and comparison of the mechanism of schemes, and may play a significant role in further research. As an example of applying the uniform algorithm, the low Mach number behaviour of the schemes is analysed. A clear and simple explanation is provided based on the wall boundary, and a concise rule is proposed to determine whether a scheme has satisfied low Mach number behaviour. [ABSTRACT FROM PUBLISHER]

An energy, volume and mass (EVM) model, involving four physico-chemical descriptor variables, i.e. van der Waals energy, internal energy, volume, and mass, to successfully predict the glass transition temperatures (Tg) of aliphatic acrylate and methacrylate polymers, has been previously described. The EVM model is as good, or better, as the previous models in terms of accuracy of calculated Tg values of polymers. However, the classical EVM approach is still limited by the validity of the experimental data that were used to derive the regressor coefficients of the quantitative structure–properties relationship (QSPR). In fact, one major problem is the large variation in the experimental Tg values that were reported in the literature. Deciding which values to use for modelling the relationship and the evaluation set of polymers is a problem to tackle with. For these reasons, an a priori design approach to the selection of a database of acrylate and methacrylate polymers for the evaluation of the EVM model has been adopted. In particular, the selection of the molecules to be considered was performed by two computed-assisted procedures based on the exchange algorithm for obtaining D-optimal design and the uniform method for finding experimental designs characterized by a stable structure. Based on the a priori design criteria, the selection of the optimal and uniform designs was “carried out”, in particular according to G-optimality. [Copyright &y& Elsevier]