Computationally synthesised inorganic and organometallic complexes : a thesis presented in partial fulfilment of the requirements of the degree of Doctor of Philosophy in Chemistry at Massey University, Albany, New Zealand

Catalytic aromatic ring C–H bond functionalisations by transition metal cyclometallation reactions are important for organic transformation reactions. The cyclometallated product, which contains a new metal–carbon bond is formed as a consequence of different types of carbon–hydrogen····metal (C–H····M) interactions. These C–H···M interactions have been known as anagostic, preagostic and agostic interactions. By nature, the anagostic interaction has mainly electrostatic components, the preagostic interaction has electrostatic components with some back-bonding from metal to C–H antibonding orbital involved and the agostic interaction has mainly covalent components when the C–H bond donates electron density to the partially occupied metal centre. Prior to the current thesis work, an in-depth study that addresses the influence of steric and electronic factors on the anagostic, preagostic and agostic carbon–hydrogen····metal interaction was missing. In this thesis, the influence of both the steric and electronic factors on the anagostic, preagostic and agostic C–H···M interactions has been studied. It is seen that the electronic and steric influences play differently for different ligand systems as with the flexible tetralone ligand, a maximum of steric and electronic influence results into another type of anagostic interaction named as the 'C-anagostic' interaction. It is also seen that a stronger steric and electronic effect can trigger agostic covalency at the anagostic stage of the reaction. The inflexible ligand ensures the short anagostic approach, which has some back-bonding character and the nature of the interaction lies into the preagostic category. Finally, the aromatic ring agostic interactions have more complexity as new donations named as 'syndetic' from C–C pi bond to metal antibonding orbitals were recognised which shares the same antibonding acceptor orbitals as the agostic donation does. The recognition of new bonding situations in C–H····M interactions can have significant implications for C–H bond functionalisation reactions

PFC Topologies for AC to DC Converters in DC Micro-Grid

With increasing dominance of renewable energy resources and DC household appliances, the novelty of DC micro grid is attracting significant attention. The key interface between the main supply grid and DC micro grid is AC to DC converter. The conventional AC to DC converter with large output capacitor introduces undesirable power quality problems in the main supply current. It reduces system efficiency due to low power factor and high harmonic distortion. Power Factor Correction (PFC) circuits are used to make supply currents sinusoidal and in-phase with supply voltages. This paper presents different PFC topologies for single phase AC to DC converters which are analyzed for power factor (PF), total harmonic distortion (THD) and system efficiency by varying output power. Two-quadrant shunt active filter topology attains a power factor of 0.999, 3.03% THD and 98% system efficiency. Output voltage regulation of the presented active PFC topologies is simulated by applying a step load. Two-quadrant shunt active filter achieves better output voltage regulation compared to other topologies and can be used as grid interface

Past, Present, and Future Dynamics of Natural Hazards in China’s Coastal Region: Resilience Implications and Role of Natural Habitat

随着全球气候变化，海岸带区域正面临着自然灾害的严重威胁，逐步加剧了海岸带地区的脆弱性以及风险性。研究海岸带地区典型自然灾害（台风）的历史演变趋势及地区的脆弱性与恢复能力，寻求有效的生态环境弹性手段来降低灾害带来的风险，对于未来海岸带地区风险预测与提升海岸社区抵抗自然灾害能力至关重要。 本论文重点以台风为例，以功耗指数（PDI）作为评估历年登陆型台风破坏性的指标，基于ArcGIS中地理空间分析方法，利用中国气象局（CMA）的台风数据，分析时间序列上台风登陆频率和破坏性及其空间分布特征。同时，综合利用斯坦福大学开发的生态系统综合估值与权衡模型（InVEST）和ArcGIS的海岸带脆弱性优化模型，...Coastal areas are facing severe threats from coastal natural hazards i.e. storm surges, typhoons, and the intensity of these hazards appear to increase due to dramatic climate change. This situation exacerbates coastal vulnerabilities, and indicates increasing future risks. Therefore, it is critical to explore the present status of community resilience to cope with natural hazards. It is also of g...学位：理学硕士院系专业：海洋与海岸带发展研究院_海洋事务学号：3042015115469

Peak to average power ratio based spatial spectrum sensing for cognitive radio systems

The recent convergence of wireless standards for incorporation of spatial dimension in wireless systems has made spatial spectrum sensing based on Peak to Average Power Ratio (PAPR) of the received signal, a promising approach. This added dimension is principally exploited for stream multiplexing, user multiplexing and spatial diversity. Considering such a wireless environment for primary users, we propose an algorithm for spectrum sensing by secondary users which are also equipped with multiple antennas. The proposed spatial spectrum sensing algorithm is based on the PAPR of the spatially received signals. Simulation results show the improved performance once the information regarding spatial diversity of the primary users is incorporated in the proposed algorithm. Moreover, through simulations a better performance is achieved by using different diversity schemes and different parameters like sensing time and scanning interval

Exploring Students’ Satisfaction with ICT Facilities at LIS Schools in the Punjab, Pakistan

This study aimed to explore library and information science (LIS) students’ satisfaction with information and communication technology (ICT) facilities at LIS schools in the Punjab, Pakistan. It also identifies the factors that motivated the students to use ICT and the benefits that they gained from the ICT. The study employed the quantitative research method to address the research questions. The quantitative data were collected from students of LIS schools in public sector universities in the Punjab, Pakistan. The findings suggest that although the students were required to use the ICT equipment to learn ICT skills as part of the LIS curriculum, most of the students used ICT tools at academic libraries and homes. The students were of the view that the use of ICT helped them develop ICT competencies. The majority of the students did not give opinions about their satisfaction with various ICT components at the schools. The outcomes of the study will help the LIS schools to upgrade and enhance their ICT facilities in order to enable students to develop ICT skills effectively and meet the job market needs in the current digital era

Power Imbalance Detection in Smart Grid via Grid Frequency Deviations: A Hidden Markov Model based Approach

We detect the deviation of the grid frequency from the nominal value (i.e., 50 Hz), which itself is an indicator of the power imbalance (i.e., mismatch between power generation and load demand). We first pass the noisy estimates of grid frequency through a hypothesis test which decides whether there is no deviation, positive deviation, or negative deviation from the nominal value. The hypothesis testing incurs miss-classification errors---false alarms (i.e., there is no deviation but we declare a positive/negative deviation), and missed detections (i.e., there is a positive/negative deviation but we declare no deviation). Therefore, to improve further upon the performance of the hypothesis test, we represent the grid frequency's fluctuations over time as a discrete-time hidden Markov model (HMM). We note that the outcomes of the hypothesis test are actually the emitted symbols, which are related to the true states via emission probability matrix. We then estimate the hidden Markov sequence (the true values of the grid frequency) via maximum likelihood method by passing the observed/emitted symbols through the Viterbi decoder. Simulations results show that the mean accuracy of Viterbi algorithm is at least $5$\% greater than that of hypothesis test.Comment: 5 pages, 6 figures, accepted by IEEE VTC conference, Fall 2018 editio