Development of X-ray Tomography Tools for Characterisation of Lithium-Sulfur Batteries

Electrochemical energy storage devices are becoming increasingly ubiquitous in both consumer and industrial applications, driven by a pressing need to reduce carbon emissions for the mitigation of global warming. The electrification of the transport and mobility sector and growth in portable electronic devices demand portable power sources with high energy densities, and lithium-ion (Li-ion) batteries have been adopted extensively in these applications. However, conventional transition metal oxide-based intercalation materials used at the positive electrode are reaching their theoretical limitations, and only relatively minor improvements in theoretical specific capacity can be achieved. // Lithium-sulfur (Li-S) batteries offer higher gravimetric theoretical specific capacity and energy density and are billed as a potential successor to Li-ion technology but suffer from limited cycle life and self-discharge due to complex multi-phase chemistry and parasitic side reactions. // To better understand the fundamental mechanisms behind these processes, advanced characterisation methods involving the use of penetrating radiation (such as X-rays and neutrons) have become invaluable tools to capture the operation and degradation of the Li-S battery. Three-dimensional techniques such as X-ray micro-tomography (micro-CT) are particularly suited to probe the heterogeneous nature of battery electrode microstructures. // In this thesis, main areas of focus will include the application of ex situ and in situ X-ray micro-CT on Li-S batteries and the broader development of in situ tomography cells. The overall scientific aims of this thesis include: measuring the three-dimensional microstructural characteristics of sulfur electrodes; elucidating the three-dimensional nature of both sulfur dissolution and redeposition as a function of state of charge; and developing a better understanding of the transport processes occurring within the Li-S battery and the influence of porosity and tortuosity on electrochemical performance. In parallel, the development of in situ tomography cells capable of electrochemical cycling is an extensive component of this thesis, with applications not solely limited to Li-S batteries or X-ray micro-CT

Satellite Fish Forecasting in Tropical Waters

South China Sea off the east coast of Peninsular Malaysia is shallow, semi-enclosed tropical sea. Most of the fishing activities in this area are concentrated in the inshore waters where marine resources are optimally exploited. However, the offshore waters still harbour a potential for fishery development. This study was carried out to assist the nation to develop offshore fisheries through sustainable development of the fisheries resources in the Malaysian Exclusive Economic Zone (EEZ) and thus harvest the fishery resources effectively and sustainably. The integration of remote sensing and GIS modeling has provided a powerful tool in fish forecasting. Understanding the relationship between oceanographic conditions and fish behavior can lead towards forecasting of fish migration and aggregation. Fish forecasting technology has been applied successfully in many countries. Findings of this study showed that some of the forecasting methods used in temperate water were unsuitable to be applied in this region. A fish forecasting model was developed in this study. The model was primarily based on the description of oceanographic phenomena from two major parameters, namely sea surface temperature and chlorophyll a. An oceanography and acoustic survey was conducted in year 2000 to verify the Potential Fishing Zone forecast. The survey's results showed that abundance of fish was located close to the upwelling boundaries, which agreed with the forecast results. For the ease of fish forecasting using GIS, ArcView interface was customized and named as the Tropical Fish Forecasting System (TroFFS)

Determination Of Pb(II), Cu(II) And Ni(II) In Water By Direct Measurement Using Uv/Vis Spectrophotometer

Logam berat merupakan unsur logam dengan ketumpatan yang tinggi dan kebanyakannya bersifat toksik pada kepekatan yang rendah. Selain itu, kepekatan logam berat dalam organisma akan semakin meningkat dengan masa disebabkan oleh sifat bioakumulasi daripada logam berat dan tidak dapat diuraikan. Teknik terkini untuk menentukan logam berat dalam air adalah melalui AAS, IC, ICP-AES, ICPMS, XRF dan elektrokimia. Teknik-teknik ini dapat memberi ketepatan yang tinggi dalam pengukuran tetapi memerlukan kos penyelenggaraan yang tinggi dan prosedur penyediaan yang rumit. Dalam penyelidikan ini, analisis kuantitatif terhadap ion Pb2+, Cu2+ dan Ni2+ dalam larutan akueus telah berjaya dijalankan dengan menggunakan UV/VIS spektroskopi tanpa reagen kimia tambahan. Penyelidikan bermula dengan mengenalpasti panjang gelombang yang berkesan untuk penyerapan dan kemudiannya disahkan dengan bilangan sampel yang banyak. Daripada penyelidikan ini, panjang gelombang berkesan untuk penyerapan di dalam julat UV bagi Pb2+ dan Cu2+ adalah daripada 200 nm hingga 230 nm dan Cu2+ dan Ni2+ daripada 600 nm hingga 800 nm. Heavy metal are metallic element with relatively high density and mostly toxic at low concentration. Heavy metal does not degrade and tends to bioaccumulate in organism over time. Current technique to determine heavy metals in water mostly via AAS, IC, ICP-AES, ICP-MS, XRF and electrochemical method,these techniques provide high precision in measurement but required high maintenance cost and complicated preparation. In this research, quantitative analysis of Pb2+, Cu2+ and Ni2+ ions in aqueous solution was carried out successfully using UV/VIS spectroscopy without additional chemical reagent. The research begins with identifying the effective absorption wavelength and was later verified using large amount of samples. From this research, the effective wavelength within UV range for Pb2+ and Cu2+ is roughly from 200 nm to 230 nm and both the Cu2+ and Ni2+ have absorbance from wavelength 600 nm to 800 nm

Automated Tool To Generate Global Clock Distribution For Spine Structure

Clock is a signal which synchronizes the logic as well as register read/write activities of a synchronous circuitry. Therefore a good way to design a reliable clock distributor network is always the top priority in IC design. Clock spine is well known for the robustness in clock signal quality delivered. Spine structure had shown good performance in terms of skew, jitter and OCV. Thus this scheme is popular for the high speed circuitry such as CPU chipset design. However, the clock spine is not commonly employed in SoC, due to the design as well as the validation complexity of this scheme. Many SoC design toolsets do not support this scheme up until now. So in this thesis, an automated methodology will be introduced and proven to integrate clock spine into a SoC to distribute a high frequency clock signal. These include the know-how and automation of the methodologies to minimize the complexity of designing the clock spine

Three dimensional norm-based knowledge management for knowledge intensive business service organizations: an organizational semiotics perspective

The utilization of knowledge enables knowledge intensive business service (KIBS) organizations, such as law firms, to perform and deliver value to their customers. Organizational semiotics views norms as knowledge that are developed through practical experience of human agents in organizations. Building on organizational semiotics and knowledge management, this paper proposes a three dimensional norm-based knowledge management (3DNKM) framework for legal sector in the UK. Abductive reasoning is adopted for guiding the research process in this paper. The three identified contextual dimensions of knowledge include customer, practice area and lawyer. For each dimension, there are informal, formal and technical norms establishing context-based knowledge. The proposed framework provides a way for KIBS organizations to manage the intertwined norms from the three dimensions and various levels

Antioxidant properties: effects of solid-to-solvent ratio on antioxidant compounds and capacities of pegaga (Centella asiatica)

The objective of this study was to evaluate the effects of solid-to-solvent ratio (1:5, 1:10, 1:15 and 1:20) on the extraction of phenolic compounds (TPC and TFC) and antioxidant capacity (ABTS and DPPH radical scavenging capacity) of C. asiatica. Solid-to-solvent ratio 1:15 was the optimum condition for extraction of phenolic compounds (TPC and TFC) with a value of 967.2 mg GAE/100 g DW and 908.3 mg CE/100 g DW, respectively and exhibited high antioxidant capacities (ABTS and DPPH radical scavenging capacities) with a value of 0.8133 mM and 2.0945 mM, respectively. TPC was positively and strongly correlated with ABTS and DPPH (r=0.808 and r=0.859, respectively) under the effects of solid-to-solvent ratio as compared to TFC, positively and moderately correlated (r=0.590, r=0.663) with ABTS and DPPH

Reducing warpage in foldable OLED screens

Organic light-emitting diode (OLED) screens are becoming popular in consumer devices due to the ability to fold such screens. However, repeated folding and unfolding is known to cause bending (warpage) at the fold. This disclosure describes techniques that reduce warpage by introducing a fan at the hinge. By Bernoulli’s principle, an increase in air speed along the fan axis causes a pressure differential perpendicular to the axis of the fan, e.g., across the fold. This pressure differential undoes the warpage