Dirac surface states of magnetic topological insulators

Magnetic topological insulator (TI) has been theoretically proposed to be a platform for inducing magnetic monopole and exhibit fascinating quantum phenomena, whereas topological superconductor can host Majorana fermions, particles that are their own antiparticles, which can be manipulated for topological quantum computing. In this dissertation, we experimentally demonstrated that by intercalation of different transition metals in the van der Waals gaps of Bi2Se3 TI, magnetism and even superconductivity can be induced. In FexBi2Se3, antiferromagnetism is induced with a transition temperature at ~ 100 K. Coexistence of the Dirac surface state with magnetism in antiferromagnetic TI that has been predicted by the theoretical study is verified. We also found the Dirac fermions originate from the bulk acting as many parallel 2D conduction channels on the material. In MnxBi2Se3, paramagnetism is induced. From Shubnikov-de Haas oscillations and quantum Hall effect (QHE) observation, we found the existence of Dirac fermions originate from the bulk, which is similar to the case of FexBi2Se3. Due to the origin of the QHE in FexBi2Se3 and MnxBi2Se3 systems is from the bulk acting as many 2D conduction channels, the electric-field exfoliation method is invented. This method is capable of obtaining a clean sample from different layered crystalline materials with the thicknesses in the range of nm and expecting to observe QHE from the surface state on both materials. Superconductivity is also induced in NbxBi2Se3 with a critical temperature of Tc = 3.2 K while the Dirac surface dispersion in its normal state is still preserved. The onset of hysteretic magnetization in NbxBi2Se3 below Tc suggests spontaneous time-reversal symmetry breaking in the superconducting state. Superconducting and magnetism mutually assist each other to give rise to a symbiosis state of this two phases --Abstract, page iv

Case study to determine the camber of post- tensioned 'I' beam

A common problem that most contractors faced in beam bridge construction was to predict the actual camber of pre-tensioned or post-tensioned beams due to prestressing in order to achieve bridge design finished levels without any unforeseen additional construction cost. Four numbers of full scale 36m long post-tensioned “I� beam with overall height of 1.98m was used to measure the actual beam camber on site by means of checking the differences of beam’s top levels while design estimation carried out is based on design code of practice for structural use of concrete BS 8110 by taken into consideration initial prestress losses due to friction and anchorage draw-in of tendons. Comparison between these two methods of evaluation reveals a significant difference. The results shows actual beam cambers measured on site are much larger compare to design prediction. The immediate camber occurred after prestressing is greater by 10.8% and continue to increase to 54.5% over 15 days with a sharp increase focused on the first 3 days after prestressing. From the findings, it’s therefore concluded that deflection of posttensioned beam cannot be predicted accurately due to many field factors which may possibly influence loss of prestress force in post-tensioned cables and behaviour of beam cambering process. However, design calculation can be used as an approximate estimation or as a guide for construction purposes Case study to determine the camber of post- tensioned 'I' beam

Amplitudes of low frequency modes in rotating B type stars

Using weakly non-linear theory of oscillation, we estimate the amplitudes of low frequency modes in a slowly pulsating B (SPB) star, taking account of the effects of rotation on the modes. Applying the formulation by Schenk et al (2002), we compute non-linear coupling coefficient between the low frequency modes and estimate the equilibrium amplitudes of the modes excited in the star, assuming the amplitudes of the unstable modes are saturated as a result of non-linear coupling with stable modes, that is, as a result of parametric instability expected between one unstable mode and two stable modes. We use the traditional approximation to calculate adiabatic and non-adiabatic oscillations in a rotating star. We find $r$-modes in a rapidly rotating star play a significant role in the amplitude determination through non-linear coupling. We also find that for low $m$ modes, the fractional amplitudes of the radiative luminosity caused by the low frequency modes are of order $10^{-4}$ to $10^{-3}$ at the surface.Comment: 14 pages, 6 figures, submitted to Monthly Notices of the Royal Astronomical Societ

Influence of boundary conditions on the behavior of an anchored reinforced earth wall

The finite element model is used to simulate the behavior of the full scale instrumented anchored reinforced wall. The validated finite element model is then used to carry out parametric studies to ascertain the influence of the boundary conditions on the behavior of the wall. The boundaries at the crest, facing and base of the wall are varied to study their effects. At the crest of the wall, slope surcharge of various geometrical dimensions are imposed. At the facing of the wall, the boundary is allowed to yield laterally by inserting a compressible geoinclusion at the back face of the wall panels. Meanwhile, at the base, the boundary is allowed to yield vertically by allowing the wall to sit on a compressible foundation soil. The behavior of the wall is determined in terms of the tensile stress distribution developed in the reinforcing bars, the summation of the maximum tension in the reinforcing bars, the summation of the tensions developed at the connection to the facing panels, the lateral movement at the facing and the vertical movement at the base

Laporan Rancangan Latihan Pelajar ( Opsyenal) Di Combits Pada 28HB. APRIL Hingga 24HB. JUN, 1986.

Laporan ini menerangkan rekabentuk dan pengimplementasi projek kami iaitu Sistem Simulasi Untuk Pemproses Mikro Motorola 6800. ( Motorola 6800 Microprocessor Simulator System ) . Secara ringkasnya, sistem ini dapat memberikan kemudahan kepada pengguna untuk mempelajari bagaimana pemproses mikro motorola 6800 berfungsi. Sistem ini cuba mencontohi segala ciri-ciri penting pemproses mikro motorola 6800. Dengan itu, sistem ini sangat berguna sebagai alat pengajaran berkomputer di dalam bidang pendidikan

Field behavior of a high anchored reinforced earth wall

Since the invention of Reinforced Earth by the French architect Hendri Vidal in 1966, numerous reinforced soil walls have been designed and constructed all over the world. In this study the focus was on a particular type of reinforced wall called Nehemiah wall which differed from the Vidal type in the sense that instead of steel strips, the reinforcing elements consisted of steel bars with anchor blocks attached at the free ends. A full scale high anchored reinforced earth wall was constructed and instrumented to capture the essential behavior of the wall. Two sections of the wall were monitored where at one of the sections polystyrene foam was inserted at the back face of the wall panel to allow for lateral deformation to take place which means that the facing was less flexible in the transverse direction. The lateral deformation, axial forces along the reinforcing bars and settlement were monitored and measured for both cases and the results were compared and discussed

Fire Performance of Endospermum malaccense Cross Laminated Timber (CLT) Treated with Fire Retardant

This study assessed the fire performance of cross-laminated timber (CLT) made from sesenduk (Endospermum malaccense) painted with a fire retardant. Teknoksafe 2407 (Tk-Exterior) and Teknoksafe 2457 (Tk Interior) fire retardants were prepared and applied to the sesenduk CLT. Fire properties such as surface spread of flame test, charring rate test, fire resistance test, and chemical property changes before and after fire testing were evaluated and compared to Control CLT. The results showed that using fire retardant effectively prevented the fire from spreading

Smart Card Implementation Model

Smart card (intelligent card) systems evolved in the 1970s and progressed through the 2000s, however, their globalization and potential has not yet been achieved. In some countries, France for example, they have been accepted and implemented to a very high degree, while in others the technology is just emerging. The present research analyses these underlying principles from a business perspective and proposes a set of procedures (a implementation plan) for the design of smart card applications. These procedures are based on the market overview and market prospective from the previous cases as a guideline to implement a smart card. I describe a generic, scalable plan that may be applied to future smart card operating systems, interfaces, and implementation schemes

Did RSPO overlook the unwelcome thoughts amongst growers and millers?

This study examined the relationship between knowledge, past experience and personal value of growers and millers intention to adopt the RSPO. This study applied the theory of Planned Behaviour (TPB) to test the proposed relationship. This research applies a quantitative approach that uses a cross-sectional questionnaire survey in order to test the proposed hypotheses. A total of 122 palm oil companies in Sabah, Malaysia were identified and collected data were analysed using the partial least squares and structural equation modelling. The findings of this study confirmed the Theory of Planned Behaviour as a great predictor of behavioural intention. In addition, knowledge, past experience and personal value were also found to have significant relationship and this resulted into the conclusion that knowledge, past experience and personal value positively influence the attitude amongst growers and millers towards RSPO. The result of this study has proven that the TPB model is a valuable, practical and has a high potential to predict human behavioural intention

Glass rain : modelling the formation, dynamics and radiative-transport of cloud particles in hot Jupiter exoplanet atmospheres

The atmospheres of exoplanets are being characterised in increasing detail by observational facilities and will be examined with even greater clarity with upcoming space based missions such as the James Webb Space Telescope (JWST) and the Wide Field InfraRed Survey Telescope (WFIRST). A major component of exoplanet atmospheres is the presence of cloud particles which produce characteristic observational signatures in transit spectra and influence the geometric albedo of exoplanets. Despite a decade of observational evidence, the formation, dynamics and radiative-transport of exoplanet atmospheric cloud particles remains an open question in the exoplanet community. In this thesis, we investigate the kinetic chemistry of cloud formation in hot Jupiter exoplanets, their effect on the atmospheric dynamics and observable properties. We use a static 1D cloud formation code to investigate the cloud formation properties of the hot Jupiter HD 189733b. We couple a time-dependent kinetic cloud formation to a 3D radiative-hydrodynamic simulation of the atmosphere of HD 189733b and investigate the dynamical properties of cloud particles in the atmosphere. We develop a 3D multiple-scattering Monte Carlo radiative-transfer code to post-process the results of the cloudy HD 189733b RHD simulation and compare the results to observational results. We find that the cloud structures of the hot Jupiter HD 189733b are likely to be highly inhomogeneous, with differences in cloud particle sizes, number density and composition with longitude, latitude and depth. Cloud structures are most divergent between the dayside and nightside faces of the planet due to the instability of silicate materials on the hotter dayside. We find that the HD 189733b simulation in post-processing is consistent with geometric albedo observations of the planet. Due to the scattering properties of the cloud particles we predict that HD 189733b will be brighter in the upcoming space missions CHaracterising ExOPlanet Satellite (CHEOPS) bandpass compared to the Transiting Exoplanet Space Survey (TESS) bandpass