Synthesis, Morphology And Superconductingproperty Characterization Of Mgxb2 And Mgb2 With Sib4 Additions

This project deals with the processing of MgB2 bulk samples and the effect of addition of SiB4. The correlation between fabrication parameters and superconducting properties was studied. MgB2 bulks were prepared by a pellet-inclosed- tube (PICT) and solid-state reaction route methods. MgB2 bulk samples were prepared at different annealing temperatures of 650°C, 700°C, 750°C and 800°C. AC susceptibility measurements showed a sharp superconducting transition in all the samples. However, MgB2, samples annealed at 650°C showed slightly low volume susceptibility compared to other samples. The critical current density (Jc) was measured using ac magnetic susceptibility measurement method. The highest critical density in magnetic field, Jc(T,H) from the magnetization measurements was recorded at 3.0×104A/cm2 (5K, 6T) and 7.0×103 A/cm2 (20K, 4T) for the 650°C annealed MgB2. X-ray diffraction (XRD) analysis showed small quantities of MgO and unreacted Mg phases as impurities in the samples. The second part of the work concentrates on Mg non-stoichiometry in MgxB2 (x = 0.8, 1.0 and 1.2) samples. The critical temperature (Tc), was significantly reduced in sample x = 0.8 and x = 1.2 as compared to sample with x=1.0. The Mg0.8B2 sample shows the highest Jc at 5K and 20K, followed by Mg1.2B2 and MgB2 samples, respectively. MgB2 shows the lowest Jc for all temperatures

Addition of Co3O4 to introduce pinning centre in Bi-Sr-Ca-Cu-O/Ag tapes

This study investigated the flux pinning capability of Co3O4 in Bi-Sr-Ca-Cu-O superconductor tapes. The Bi-Sr-Ca-Cu-O powders were prepared by using the co-precipitation technique with the addition of Co3O4 as pinning centre to enhance the transport critical current density (Jc) of the system. The Ag sheathed (Bi,Pb) 2Sr2Ca2Cu3O10 (2223) and (Bi,Pb) 2Sr2Ca2Cu3O10- ( Co3O4)0.01 high temperature superconductor tapes were fabricated using the powder in tube method. The effects of Co3O4 addition on the microstructure, critical temperature and critical current density were studied. The Jc value of the Co3O4 added tapes increased to ~4500 A/cm2. This tape showed the highest Jc and Tc when heated at 845°C for 50 hours. XRD diffraction pattern showed that the addition of Co3O4 inhibits the 2223 phase formation. This study shows that magnetic particles can act as effective pinning centres leading to the enhancement of Jc in the system

Design of a high speed and low latency crypto-processor ASIC

This paper presents the design of an ultra high speed crypto-processor for next generation IT security. It addresses the next generation IT security requirements: the resistance against all attacks and high speed with low latency. The proposed processor is capable of generating cryptographically secured information at a rate of multi-ten Gbps. The performance of the processor is compared with that of other researchers which proves it's superiority over them

Enhanced critical current density in MgB2 with Dy2O3 particle additions

This paper reports on the effect of oxide particle Dy2O3 additions on the superconducting properties of MgB2. The polycrystalline samples were prepared by well mixing magnesium and boron elemental powders, followed by heat treatment for in situ reaction in inert gas environment. All the samples showed MgB2 as the main phase with MgO and DyB4 as impurities. Magnetization measurements showed that the superconducting transition temperature, Tc remained largely unchanged (37.5 – 38K) even for Dy2O3 additions up to 15.0 wt.%. However, the transition curve was broadened in samples with larger amount of additions. The best sample with only 0.5 wt.% Dy2O3 additions had a Jc of around a factor of 4 higher compared to the pure sample at 6K(1T). Tem imaging showed the distribution of nano precipitates of DyB4 and MgO within the grain which may improve the pinning leading to enhancement in critical current density, Jc

Simple calculation of the anistropic factor for minimum current path in MgB2 material using the extrapolated Kramer field as priori parameter

The volume flux pinning force density of MgxB2 (x = 0.8, 1.0 and 1.2) materials was calculated for grains boundary and point pinning potentials. Stoichiometric Mg0.8, MgB2, and Mg 1.2B2 samples were prepared by the conventional solid state reaction method. Three pellets were annealed at temperature range of 650-800°C. Structural analysis revealed large values for FWHM at (hkl) (110)(°) which indicates distortion in the boron plane of these specimens. The a and c – axis lattice parameters showed respective contraction and elongation with the increase in processing temperature. The low crystallinity found in Mg0.8B2 and Mg1.2B2 specimens was concluded to be due to structural defects, which act as flux pinning centres. Experimental anisotropic factor and the minimum fraction for current path, obtained from the framework of current percolation theory were used to explain the strong field dependence of the critical current density, Jcin the specimens. The summit of the maximum pinning force density was shifted to lower magnetic field position with the increase of anisotropy. The scaling laws were employed in a Kramer– like field in order to identify the dominant pinning mechanism correspondence to the summit of maximum pinning. For MgB2 specimens however, a renormalization field based on the current percolation exposition is considered for the identification of their dominant pinning since it is very difficult to account for the flat behaviour of the pinning force in the weakened current region of these specimens

The effect of magnetic nanoparticle addition on the superconducting properties of Bi1.6Pb0.4Sr2Ca2Cu3Oδ superconductors

Sm2O3 nanoparticle was added to Bi-2223 superconductor prepared by solid state reaction technique with intermediate grinding. A stiochiometric precursor of x=0.00-0.05 Sm2O3 nanoparticle is systematically added to the well balanced Bi1.6Pb0.4Sr2Ca2Cu3Oδ in order to trace the effect of nanoparticles addition to the system. Microstructure, resistive transitions, phase volume, and cell parameters were hence investigated. Addition of Sm2O3 nanoparticle is found to slowly decrease the Bi-2223 phase volume and the resistive transitions for x=0-0.02 samples whereas accelerated formation of the Bi-2212 phase is detected for further additions. Changes in superconducting properties of Sm-added Bi-2223 system were discussed and the findings were further compared with available literature

Experimental study on the phase formation of MgxB2 (x=0.8, 1.0, 1.2)

Phase formation of Magnesium diboride Mgx B2(x=0.8, 1.0, 1.2) by in situ reaction of Magnesium (Mg) and Boron (B) at different annealing temperature by varying the nominal Mg composition was compared. The X-ray difffraction pattern indicates that Magnesium Oxide (MgO) is the major secondary phase. Some unreacted Mg was found for nominally stoichiometric and Mg excess samples annealed at or below 750°C. However, no unreacted Mg was detected by XRD for Mg deficient samples. Scanning Electron microscopy images show the porous nature of synthesised samples

MANUAL FOR IBADAH CAMP ORGANIZER A PART OF THE IIUM FLAGSHIP ENTITLED “GENDER DYSPHORIA”

Maknyah or male-to-female transgender are those who transform their identity biologically from male to female through crossdressing and their lifestyle associated with homosexuality. Crossdressing and homosexuality are unlawful in accordance with Islamic practices. Often, these transgenders are associated with being sex workers in major hotspots such as in Federal Territory Kuala Lumpur, Selangor, Negeri Sembilan, Pulau Pinang, Pahang and Sarawak.1 It is estimated that the population size of sex workers in Malaysia in 2018 is 37,000 (22,000 Female Sex Workers and 15,000 Transgender Sex Workers). Despite the reducing number of transgender sex workers in Malaysia (as compared to previous Key Population Estimates in 2010), it is still a concern to Muslims and this trend needs to be relieved promptly

Impact of gas composition variations on flame blowout and spectroscopic characteristics of lean premixed swirl flames

The injection of gases from different oil and gas fields and external sources such as liquefied natural gas increases operational risks for the relevant gas turbine power plant operators. In practice, the absence of interchangeability specifications in the gas supply network code has caused combustion blowout, wear and tear to occur due to combustion dynamics and diluent effects. Understanding the effects of diluents on natural gas combustion is essential to ensure the safe operation of existing facilities. The present work investigates the flame stability and spectroscopic characteristics of diluents-containing natural gas by using a swirl flame burner. Stable and continuous swirl flames were successfully established using different types of gas compositions, including those diluted with nitrogen and carbon dioxide. Diluting the modelled natural gas with CO2 and N2 results in higher blowout limit as compared to the baseline pure methane case. Preheating the burner and mixtures can extend the flame blowout limits, although the effect of CO2 on flame blowout is more pronounced than that of N2 due to its higher heat capacity. This work shows the effects of non-reactive diluents on gas turbine flame can be significant, particularly at high-level dilutions. Mitigation measures such as gas composition and flame spectroscopy monitoring can be deployed to ensure safe operation of the system. By using the statistical analysis technique of linear regression, the proportions of all the fuel mixture components of CH4, C2H6, CO2 and N2, alongside temperature were found to be significant factors in determining flame blowout limits. The developed predictor equations for OH intensity and lean blowout equivalence ratios show the predictive capability of &gt;89% at 90–95% confidence level.</p