Ab initio study of low pH vanadium (V)

vi, 137 leaves : ill. (chiefly col.) ; 29 cm.Includes abstract and appendix.Includes bibliographical references (leaves 98-100).The aqueous chemistry of the low pH vanadium (V) species is complex. These low concentration species of vanadium (V) cannot be studied by conventional experimental methods to obtain the important structural information of vanadium compounds. This project studied three compounds of vanadium (V): VO[subscript 2][superscript +] , H[subscript 3]VO[subscript 4] and H[subscript 2]VO[subscript 4][superscript -] using ab initio computational methods (HF, MP2, B3LYP, CCSD(T) and CPMD). The geometries of hydrated (up to six water molecules) VO[subscript 2][superscript +], H[subscript 3]VO[subscript 4] and H[subscript 2]VO[subscript 4][superscript -] were calculated using the ab initio methods. The effects of hydration on the bond lengths and vibrational frequencies of these compounds were established. The coordination of water molecules weakened the bonds and decreased their corresponding vibrational frequencies. The hydrogen bonded water molecules strengthened the bonds and increased their corresponding vibrational frequencies. The mechanism of the conversion of H[subscript 2]VO[subscript 4][superscript -] to VO[subscript 2][superscript +] was studied. The complete hydration of H[subscript 2]VO[subscript 4][superscript -] increased the coordination number to five and the double protonation of its hydroxo ligands produced the VO[subscript 2][superscript +]

Deadlock-Free Multi-Path Routing for Torus-Based NoCs

In our previous work, a multi-path routing (MPR) scheme was proposed to maximize the data throughput for torus-based NoCs by utilizing multiple paths for concurrent data transmission. In this paper, a deadlock-free virtual channel model is proposed for the MPR scheme. In this virtual channel model, every physical channel on the network is split into about 3.5 virtual channels on average. It is proved that any minimal routing algorithm (including the MPR scheme) using this model is deadlock-free. The MPR scheme employing this new virtual channel model is still a fully adaptive one. The performance of the MPR scheme using the proposed virtual channel model is evaluated through simulations and compared with the fully adaptive single-path minimal routing (SPR) scheme with the same virtual channel model. Simulation results show that MPR achieves better average message latency and normalized accepted traffic than SPR under both uniform and nonuniform traffic in general

Cross-Attention is Not Enough: Incongruity-Aware Multimodal Sentiment Analysis and Emotion Recognition

Fusing multiple modalities for affective computing tasks has proven effective for performance improvement. However, how multimodal fusion works is not well understood, and its use in the real world usually results in large model sizes. In this work, on sentiment and emotion analysis, we first analyze how the salient affective information in one modality can be affected by the other in crossmodal attention. We find that inter-modal incongruity exists at the latent level due to crossmodal attention. Based on this finding, we propose a lightweight model via Hierarchical Crossmodal Transformer with Modality Gating (HCT-MG), which determines a primary modality according to its contribution to the target task and then hierarchically incorporates auxiliary modalities to alleviate inter-modal incongruity and reduce information redundancy. The experimental evaluation on three benchmark datasets: CMU-MOSI, CMU-MOSEI, and IEMOCAP verifies the efficacy of our approach, showing that it: 1) outperforms major prior work by achieving competitive results and can successfully recognize hard samples; 2) mitigates the inter-modal incongruity at the latent level when modalities have mismatched affective tendencies; 3) reduces model size to less than 1M parameters while outperforming existing models of similar sizes.Comment: *Equal contributio

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Ph.DDOCTOR OF PHILOSOPH

Fundamental studies on nano-composite phase change materials (PCM) for cold storage applications

This thesis studies the thermophysical properties and the phase change behaviour of EG-water and Salt-water based PCMs for cold storage applications, and investigates the role of adding MCNT on the thermophysical properties and the phase change processes. First, the structure of MCNT clusters is linked to the rheological behaviour of the nanofluids by fitting the experimental viscosity data to the modified K-D model. Second, the MCNT cluster information is used to predict thermal conductivity. The effective thermal conductivity of nanofluids not only relies on the particle concentration, but also depends on the particle cluster structure. The specific heat of MCNT nanofluids is decreasing proportionally with the concentration of MCNT. The supercooling degree of EG-water and salt-water based samples can be reduced by adding MCNT particles. The crystallization process of salt-water basefluid and nanofluid was observed and recorded under an optical microscope with cooling stage. Adding MCNT can promote the crystal growth rate