"Magnetoscan": A Modified Hall Probe Scanning Technique for the Detection of Inhomogeneities in Bulk High Temperature Superconductors

We present a novel technique for the investigation of local variations of the critical current density in large bulk superconductors. In contrast to the usual Hall probe scanning technique, the sample is not magnetized as a whole before the scan, but locally by a small permanent magnet, which is fixed near the Hall probe, during the scanning process. The resulting signal can be interpreted as a qualitative measure of the local shielding currents flowing at the surface.Comment: 8 pages, 4 figure

Studies of cracking behavior in melt-processed YBCO bulk superconductors

An important phenomenon in bulk superconductors fabricated by top-seeded-melt growth (TSMG) is the formation of cracks due to the inherent brittleness of the YBa2Cu3O7-δ (Y-123) phase matrix. These form during the fabrication of the superconducting monolith and play an important role in the limitation of current flow. However, cracks may also form during cooling cycles of the sample to liquid nitrogen temperatures. In this investigation, macrocracks along the c-direction, in particular were analyzed microscopically before and after cooling. In addition we attempt to resolve the c-axis macrocrack formation pattern using the magnetoscan technique

Evolution of the fishtail-effect in pure and Ag-doped MG-YBCO

We report on magnetic measurements carried out in a textured YBa$_2$Cu$_3$O$_{7-\delta}$ and YBa$_2$(Cu$_{1-x}$Ag$_x$)$_3$O$_{7-\delta}$ (at $x \approx$ 0.02) crystals. The so-called fishtail-effect (FE) or second magnetization peak has been observed in a wide temperature range 0.4~$<T/T_c<$~0.8 for $\textbf{H}\parallel c$. The origin of the FE arises for the competition between surface barrier and bulk pinning. This is confirmed in a non-monotonically behavior of the relaxation rate $R$. The value $H_{max}$ for Ag-doped crystals is larger than for the pure one due to the presence of additional pinning centers, above all on silver atoms.Comment: 6 pages, 6 figure

Studies of cracking behavior in melt-processed YBCO bulk superconductors

An important phenomenon in bulk superconductors fabricated by top-seeded-melt growth (TSMG) is the formation of cracks due to the inherent brittleness of the YBa2Cu3O7-δ (Y-123) phase matrix. These form during the fabrication of the superconducting monolith and play an important role in the limitation of current flow. However, cracks may also form during cooling cycles of the sample to liquid nitrogen temperatures. In this investigation, macrocracks along the c-direction, in particular were analyzed microscopically before and after cooling. In addition we attempt to resolve the c-axis macrocrack formation pattern using the magnetoscan technique

Optimasi Kekuatan Tekan Beton Kolom Silinder Diperkuat Selubung Komposit Laminat Jute Dengan Metode Anova

Tujuan penyelidikan ini ialah analisis kekuatan tekan spesimen beton silinder yang diperkuat dengan selubung komposit laminat jute (KLJ), analisis distribusi data yang dihasilkan dari eksperimental yang telah dilakukan dengan menggunakan metode fungsi kerapatan variasi data dan analisis optimasi kekuatan komposit laminat jute epoksi sebagai penguat struktur beton akibat beban statik tekan.  Metode yang digunakan ialah metode Analysis of Variance (Anova). Hasil penelitian ini ialah kekuatan tekan maksimum rata-rata diperoleh pada jumlah selubung KLJ sebanyak 3 lapis, yaitu 23.84 MPa atau mengalami peningkatan kekuatan tekan rata-rata hingga 40 % tehadap spesimen tanpa selubung. Hasil analisis terhadap fungsi kerapatan variasi terhadap seluruh data uji menunjukkan bahwa data-data hasil eksperimental tersebut adalah terdistribusi secara normal pada interval populasi rata-rata ± standar deviasi. Berdasarkan hasil analisis Anova memperlihatkan bahwa nilai F0 hasil eksperimental yaitu 0,93 adalah jauh lebih kecil jika dibanding dengan nilai F-Distribusi dengan toleransi a = 5 %, DoF treatment = 2, dan DoF error = 6, yaitu 5,14. Dengan demikian, pemberian selubung KLJ pada spesimen beton silinder terbukti secara signifikan mempengaruhi peningkatan kekuatannya

PHYSICO-CHEMISTRY OF GEOPHAGIC SOILS INGESTED TO RELIEF NAUSEA AND VOMITING DURING PREGNANCY

Background: Nausea and vomiting during pregnancy (NVP) is one of the most common symptoms experienced by most women during their first trimester of pregnancy. For some of these women, especially the more tribally and culturally oriented ones, soil ingestion is one of the remedies used to curb NVP. The aim of this study was to physico-chemically characterise selected geophagic soils from Cameroon and South Africa, ingested for the relief of NVP and to appraise their ability to meet the needs of geophagic individuals. Materials and Methods: Thirteen geophagic soil samples (6 from Cameroon and 7 from South Africa) were obtained from traditional mine sites and physico-chemically characterized. The following tests were conducted; particle size distribution (PSD), liquid limit (LL), plastic limit (PL), plasticity index, soil pH and electrical conductivity (EC). Results: The samples were texturally classified as silt loam, of medium to high plasticity with normal to active swelling potentials. The samples were generally acidic (pH of 3.1 – 6.1) with low EC (average of 92.71µS/cm). Conclusion: Based on soil consistency limits and pH, the samples were found to be suitable for use as remedy for NVP with soils from Cameroon displaying the most optimum properties

Growth-related profiles of remanent flux in bulk melt-textured YBaCuO crystal magnetized by pulsed fields

We have studied the remanent magnetic flux distribution in bulk melt-textured YBa2Cu3O7 (YBCO) crystals after their magnetization in quasi-static and pulsed magnetic fields up to 6T. It has been shown that, provided that the magnetic pulse is sharp enough and its amplitude much exceeds the twice penetration magnetic field, the pulse magnetization technique becomes extremely sensitive to the sample inhomogeneities. Using this method with appropriate parameters of the magnetic pulse, we have particularly demonstrated that the growth of YBCO crystals in the growth sectors (GSs) responds for a macroscopic arrangement of weaks links -- they mostly appear inside of GSs, but not along the GS boundaries.Comment: 8 pages in LaTeX2e, 5 figures. Revised version, submitted to Supercond. Sci. Techno

Pengaruh Roe, Der, Tato, Dan Per Terhadap Harga Saham Perusahaan Properti Dan Real Estate Yang Go Publik Di Bursa Efek Indonesia

Investors require accurate information for making decision, such as return on equty (ROE), debt to equity ratio (DER), total assets turnover (TATO), and price earning ratio (PER). The purpose of this study is to determine the influence of ROE, DER, TATO, and PER either jointly or individually to the stock price. Population of this study is the real estate company which is go public in Indonesian Stock Exchange between 2007 – 2010 as much as 45 company. Sample of this study as much as 21 company. Methods of sample selection was done by purposive sampling with the following considerations: (1) consecutively listing between 2007 – 2010; (2) the required data is available; (3) book closing per 31 December. The study concluded that: ROE, DER, TATO, and PER jointly have significant effect on stock price (F value = 3.268 &gt; F table = 2.51 on sig. F = 0.017). The contribution of the four independent variables together to Stock Price is 16.3%, while the remaining 83.7% are affected by other variables that not examined in this study. ROE and PER individually have significant effect on stock price. DER and TATO doesnt have significant effect on stock price