Beamformer Based on Quaternion Processes

In this chapter, the problem of quaternion beamformer based on linear and widely linear hypercomplex processing is investigated in scenarios, where there exist one signal and one interference that are uncorrelated. First, we introduce brief information about the quaternion algebra and a quaternion model of linear symmetric array with two-component electromagnetic (EM) vector-sensors is presented. Based on array’s quaternion model, a quaternion MVDR (QMVDR) beamformer is derived and its performance is analysed. Second, we propose the general expression of a quaternion semi-widely linear (QSWL) beamformer and derive its useful implementation and the array’s gain expression. Finally, we give the main results of Monte Carlo simulation

Quasi-homomorphisms of quantum cluster algebras

In this paper, we study quasi-homomorphisms of quantum cluster algebras, which are quantum analogy of quasi-homomorphisms of cluster algebras introduced by Fraser. For a quantum Grassmannian cluster algebra $\mathbb{C}_q[{\rm Gr}(k,n)]$, we show that there is an associated braid group and each generator $\sigma_i$ of the braid group preserves the quasi-commutative relations of quantum Pl\"{u}cker coordinates and exchange relations of the quantum Grassmannian cluster algebra. We conjecture that $\sigma_i$ also preserves $r$-term ($r \ge 4$) quantum Pl\"{u}cker relations of $\mathbb{C}_q[{\rm Gr}(k,n)]$ and other relations which cannot be derived from quantum quantum Pl\"{u}cker relations (if any). Up to this conjecture, we show that $\sigma_i$ is a quasi-automorphism of $\mathbb{C}_q[{\rm Gr}(k,n)]$ and the braid group acts on $\mathbb{C}_q[{\rm Gr}(k,n)]$

Observation of gapless corner modes in synthetic translation dimensions

The introduction of synthetic dimensions in topological photonic systems enriches the exploration of topological phase of light in higher-dimensional space beyond three-dimensional real-space. Recently, the gapless corner modes of topological photonic crystals under translational deformation have been proposed, but their experimental observation is still absent. Here, we observe the gapless corner modes in a photonic crystal slab under translational deformation. The corner mode exhibits a frequency dependence that can be tuned through the translation of the slab. Importantly, we find that the existence of gapless corner modes is independent of the specific corner configuration. The gapless corner modes are experimentally imaged via the near-field scanning measurement, and validated numerically by full-wave simulations. Our work contributes to the advancement of topological photonics and provides valuable insights into the exploration of gapless corner modes in synthetic dimensions

Barriers to the transition towards off-site construction in China: An Interpretive structural modeling approach

Off-site construction (OSC) has been recognized as an approach to transform the construction sector from a labor–intensive to a modernized and green industry. Despite a number of advantages, the development of OSC still remains its infancy in China due to various interactive barriers. Some studies have been conducted to explore the barriers to the OSC adoption. However, very few studies attempted to investigate the complex interrelationships among these barriers. In order to fill this gap, this study adopts Interpretive Structural Model (ISM) technique to explore the interrelationships amongst barriers to the OSC adoption in China. Firstly, critical barriers were identified through literature review and semi-structured interviews with various stakeholders. Then, the overall structure amongst barriers was revealed through ISM technique. By using the Matriced’ Impacts Croise's Multiplication Appliquée a UN Classement (MICMAC) technique, the barriers were classified into four groups according to their driving-power and dependence power. The results indicate that specific attentions should be given to inadequate policy and regulations, lacking knowledge and expertise, dominated traditional project process as well as low standardization. The research findings provide valuable information for policy-makers on the overall structure amongst barriers. These results shed lights on effectively developing measures to facilitate the OSC adoption in the construction sector