There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

PEEK Biomaterials in Trauma, Orthopedic, and Spinal Implants

Conductive polymers: towards a smart biomaterial for tissue engineering.

Epoxies represent a good host polymer matrix for addition of fillers to create composite systems. By adding fillers or additives during the solution phase it is possible to easily create a composite system with a relatively high state of dispersion. Since epoxies represent good dielectric materials, much interest has been shown in the electrical charge characterization of such materials. This investigation studies the effect of addition of micro/Nano silicon dioxide and boron nitride to an epoxy matrix with respect to charge accumulation and transport. Data was collected using a PEA system on unfilled and filled systems with analysis and discussion on the effects that the fillers were having.

Space charge distribution in filled epoxy composites containing micro and nano fillers

Insulating oils are a major component of high voltage plant, including transformers, switchgear and cables. Consequentially, in terms of plant failure, changes in the electrical characteristics of the oil during ageing are of crucial importance. To address this issue, commercial insulating oil was subjected to controlled ageing under laboratory conditions. The electrical properties of the aged oils were then characterized using dielectric spectroscopy. The data suggest that a degree of electrical conductivity occurs in the aged oils, which reduces the insulating properties of the oil as ageing proceeds. The role of atmosphere and additives on the electrical properties of the oils were also explored. Results are compared with model samples, which contain known amounts of materials that may occur as by-products of the ageing process.

On the electrical properties of insulation oils

With polymer insulation being more and more widely used in high voltage applications, there is much scope for the introduction of “smart” moieties into the bulk polymer in order to fulfill application-specific requirements. For example, electric field sensitive fluorophores can be designed and introduced into the dielectric such that changes in fluorescent properties are indicative of the local electrical environment or dielectric degradation. This paper will describe initial investigations into the dielectric behavior of a model system whereby fluorescent solid supported pyrene (filler) was blended into bulk polystyrene (PS). The electrical breakdown strength, fluorescent response and dielectric loss of the blended samples were compared in order to determine the effects of fluorescent filler introduction on electrical properties of PS.

Towards intelligent insulation technologies

The morphology of semi-crystalline polymers

Two polyethylene blends crystallized under non-isothermal conditions were compared to a crosslinked polyethylene (XLPE) reference material. One blend contained a gelation agent, which forms a network structure within the polymer host. Compared to the reference material, the blends offered higher melting points, increased electrical breakdown strength and enhanced thermo-mechanical stability at high temperatures. Dissipation of stored charge was improved in the blend containing the gelation agent. The provision of recyclable insulation capable of operating at higher temperatures than XLPE, combined with enhanced dielectric properties, may prove invaluable to cable manufacturers.

Alun S. Vaughan

Papers

Space charge distribution in filled epoxy composites containing micro and nano fillers

On the electrical properties of insulation oils

Towards intelligent insulation technologies

The morphology of semi-crystalline polymers

Polymer Blend Systems for HVDC Cable Applications