Theoretical analysis of gap potential functions and corner saturation in 2-D, symmetric magnetic recording heads with tilted gap corners

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.The two-dimensional, semi-infinite symmetrical head with gap corner angle and in the absence of a soft underlayer was postulated in the early history of magnetic recording to develop the field theory necessary for modeling and understanding the record and readout processes. Practical and mathematical considerations limited the theory of this general head structure to corner angles= 90° (right-angled head) and= 0° ("thin" gap head). Thus explicit and analytical solutions for the gap potential function and its Fourier transform (necessary for determining the fields beyond the head surface) as functions of corner angle for symmetrical heads remain unavailable. Moreover, saturation in the gap corners associated with reduction of the gap corner angle is not well understood and characterised. In this article, the scalar magnetic potential of a single 2-D corner is derived exactly, and superposition of two corner potentials was then used to derive an approximate analytical expression for the gap potential function of 2-D symmetrical heads with arbitrary corner angle. The derived expressions for the potentials and fields were in excellent agreement with exact analytical solutions and with finite-element solutions for all≤ 90°. The derived expressions were also shown to predict accurately the surface potentials of other symmetrical head structures including the tilted pole head, the parallel plate head and the tilted plate head. An analytical approximation for the Fourier transform of the surface field for the 2-D symmetrical head was derived, showing the shift in the spectral gap nulls towards longer wavelengths with reducing gap corner angle. Systematic finite-element calculations of the static vector potential for the 2-D symmetrical head were carried out using a nonlinear B-H core material model for different driving fields and corner angles. Corner saturation was characterised by the driving fields that yield 10% root-mean-square deviation from the linear material response. The simulations correctly predicted the known saturation driving field/2 for right-angle heads (is the core saturation magnetisation), and revealed a generalisation for all≤ 90° in the form of the exponential dependence exp( ), where the free parameters and were determined from fitting to the finite-element simulations for both field maxima and their gradients

Analisis Bimbingan Skripsi Dan Ketersediaan Sumber Belajar Mahasiswa Dalam Menyusun Skripsi Pada Pendidikan Akuntansi FKIP UMS Angkatan 2014

This study aims to determine: 1) the influence of thesis guidance in students preparing the thesis, 2) the influence of the availability of learning resources in students preparing the thesis, 3) the influence of thesis guidance and the availability of learning resources in students preparing the thesis on accounting education FMS UMS force 2014. This study using this type of quantitative research. Population in this research is student of accounting education FKIP UMS force 2014 which is taking thesis. The result of t test of thesis guidance variable in preparing thesis shows that t count > t table is 4,214> 1,97756 with value probability significance t table is 4.726> 1.97756 with the probability significance value F table is 29.000> 3.06 and probability significance value <0,05 is 0.000 mean thesis guidance variable and availability of learning source to variable arrangement have determination significant to variable make thesis. The coefficient of determination (R2) is 0.336. The meaning of the influence given by the contribution of thesis guidance variable and the availability of learning resources simultaneously to the variable of preparing the thesis is 33.6%, while the rest is influenced by other variables that are not in the research

Understanding the importance of the temperature dependence of viscosity on the crystallization dynamics in the Ge2Sb2Te5 phase-change material

This is the final version of the article. Available from AIP Publishing via the DOI in this record.The crystallization dynamics in the phase-change material Ge2Sb2Te5 is modelled using the more detailed Master equation method over a wide range of heating rates commensurate with published ultrafast calorimetry experiments. Through the attachment and detachment of monomers, the Master rate equation naturally traces nucleation and growth of crystallites with temperature history to calculate the transient distribution of cluster sizes in the material. Both the attachment and detachment rates in this theory are strong functions of viscosity, and thus, the value of viscosity and its dependence on temperature significantly affect the crystallization process. In this paper, we use the physically realistic Mauro−Yue−Ellison−Gupta−Allan viscosity model in the Master equation approach to study the role of the viscosity model parameters on the crystallization dynamics in Ge2Sb2Te5 under ramped annealing conditions with heating rates up to 4 × 104 K/s. Furthermore, due to the relatively low computational cost of the Master equation method compared to atomistic level computations, an iterative numerical approach was developed to fit theoretical Kissinger plots simulated with the Master equation system to experimental Kissinger plots from ultrafast calorimetry measurements at increasing heating rates. This provided a more rigorous method (incorporating both nucleation and growth processes) to extract the viscosity model parameters from the analysis of experimental data. The simulations and analysis revealed the strong coupling between the glass transition temperature and fragility index in the viscosity and crystallization models and highlighted the role of the dependence of the glass transition temperature on the heating rate for the accurate estimation of the fragility index of phase-change materials from the analysis of experimental measurements.The authors would like to acknowledge the financial support from the Ministry of Higher Education of Iraq for the Ph.D. scholarship of Mr. Aladool

Similarity Measure Development for Case-Based Reasoning- A Data-driven Approach

In this paper, we demonstrate a data-driven methodology for modelling the local similarity measures of various attributes in a dataset. We analyse the spread in the numerical attributes and estimate their distribution using polynomial function to showcase an approach for deriving strong initial value ranges of numerical attributes and use a non-overlapping distribution for categorical attributes such that the entire similarity range [0,1] is utilized. We use an open source dataset for demonstrating modelling and development of the similarity measures and will present a case-based reasoning (CBR) system that can be used to search for the most relevant similar cases

An improved design of a fully automated multiple output micropotentiometer

This paper describes in details a new design of a fully automated multiple output micropotentiometer (?pot). A prototype has been built at the National Institute for Standards (NIS), Egypt to establish this highly improved AC voltage source in the millivolt range. The new device offers three different outputs covering a wide frequency range from only one outlet. This valuably supports the precise sourcing ranges of low AC voltage at NIS. The design and the operation theory of this prototype have been discussed in details. An automatic calibration technique has been introduced through specially designed software using the LabVIEW program to enhance the calibration technique and to reduce the uncertainty contributions. Relative small AC-DC differences of our prototype in the three output ranges are fairly verified. The expanded uncertainties of the calibration results for the three output ranges have been faithfully estimated. However, further work is needed to achieve the optimum performance of this new device

Temperature effects on the electrical performance of large area multicrystalline silicon solar cells using the current shunt measuring technique

The temperature effects on the electrical performance of a large area multicrystalline silicon solar cell with back-contact technology have been studied in a desert area under ambient conditions using the current shunt measuring technique. Therefore, most of the problems encountered with traditional measuring techniques are avoided. The temperature dependency of the current shunt from 5ºC up to 50ºC has been investigated. Its temperature coefficient proves to be negligible which means that the temperature dependency of the solar cell is completely independent of the current shunt. The solar module installed in a tilted position at the optimum angle of the location, has been tested in two different seasons (winter and summer). The obtained solar cell short circuit current, open circuit voltage and output power are correlated with the measured incident radiation in both seasons and all results are discussed

Frequency Response of a Moving Two-Dimensional Defect in Magnetic Flux Leakage Inspection

This is the author accepted manuscript. The final version is available from IEEE via the DOI in this record The detection of magnetic flux leakage (MFL) enables nondestructive detection and characterization of defects in magnetic structures. In this letter, Fourier transforms of the leakage fields from a two-dimensional surface defect are evaluated to produce analytical expressions for the frequency response of MFL signals detected by a flux-sensitive sensor. The expressions show the correlation between the spectral response of the leakage fields, defect dimensions, and sensing element lift-off spacing as a product of frequency-dependent defect-width loss function, spacing loss function, and thickness enhancement function. The lower and upper band edges of the band-limited leakage magnetic fields are theoretically identified. A spectral method for sizing of defects is proposed based on the frequency response.Innovate U

Influence of the conductivity on spin wave propagation in a Permalloy waveguide

This is the final version. Available from AIP Publishing via the DOI in this recordThe influence of the electrical conductivity of a Permalloy waveguide on the spin wave propagation was investigated using the finite-element solution of the combined system of quasistatic electromagnetic potential and linearized LLG (Landau–Lifshitz–Gilbert) equations. The difference in the group velocity between the conductive and nonconductive waveguides becomes large for films over 300 nm thick, and the difference is very small for film thicknesses less than 100 nm. The observed enhancement of the group velocity with increasing film thickness is attributed to the damping caused by the electrical conductivity, which leads to narrowing of the spin wave packet envelope and shorter arrival times of propagating waves. The basic characteristics of the dispersion relations do not change between conductive and nonconductive films for small film thicknesses less than 300 nm. The simulated dispersion relations indicate shift of their maximum intensity toward lower wavenumbers and, therefore, increase in the group velocity with increasing thickness. The simulated decay length of the spin waves for conductive films initially increases but then decreases with increasing thickness, which agrees well with the experimental results. The extracted damping coefficients from both simulations and the experiment agree very well and increase proportionally with d2, where d is the film thickness, due to the additional eddy current damping. The observed thickness and conductivity dependence of spin wave propagation is crucial for magnonics research and toward the development of future spin wave devices using metal films.JSPS KAKENHICentral Research Institute of Fukuoka Universit

Electrical performance study of a large area multicrystalline silicon solar cell using a current shunt and a micropotentiometer

In this paper, a new technique using a Current Shunt and a Micropotentiometer has been used to study the electrical performance of a large area multicrystalline silicon solar cell at outdoor conditions. The electrical performance is mainly described by measuring both cell short circuit current and open circuit voltage. The measurements of this cell by using multimeters suffer from some problems because the cell has high current intensity with low output voltage. So, the solar cell short circuit current values are obtained by measuring the voltage developed across a known resistance Current Shunt. Samples of the obtained current values are accurately calibrated by using a Micropotentiometer (μpot) thermal element (TE) to validate this new measuring technique. Moreover, the solar cell open circuit voltage has been measured. Besides, the cell output power has been calculated and can be correlated with the measured incident radiation

Prestasi Belajar Hukum Pajak Dan Perpajakan Ditinjau Dari Aspek Kognitif Dan Rutinitas Belajar Pada Mahasiswa Program Studi Pendidikan Akuntansi Universitas Muhammadiyah Surakarta Angkatan 2010

Tujuan dari penelitian ini adalah untuk mengetahui: 1) Untuk mengetahui pengaruh kemampuan kognitif mahasiswa dalam memahami materi dan soal-soal terhadap Prestasi Belajar Hukum Pajak dan Perpajakan; 2) Untuk mengetahui pengaruh rutinitas belajar mahasiswa terhadap Prestasi Belajar Hukum Pajak dan Perpajakan; 3) Untuk mengetahui pengaruh kemampuan kognitif dan rutinitas belajar terhadap Prestasi Belajar Hukum Pajak dan Perpajakan. Penelitian ini termasuk jenis penelitian deskriptif kuantitatif dengan penarikan kesimpulan melalui analisis statistik. Populasi dalam penelitian ini adalah 201 mahasiswa Program Studi Pendidikan Akuntansi, Fakultas Keguruan dan Ilmu Pendidikan, Universitas Muhammadiyah Surakarta, 2010. Sampel diambil sebanyak 132 mahasiswa. Data yang diperlukan diperoleh melalui angket dan dokumentasi. Angket sebelumnya diujicobakan dan diuji validitas serta diuji reliabilitas. Teknik analisis data yang digunakan adalah analisis regresi linier berganda, uji F, uji t, dan sumbangan relatif dan efektif. Hasil analisis regresi memperoleh persamaan garis regresi: Y = 0,329 + 0,029X1 + 0,019X2. Persamaan menunjukkan bahwa prestasi belajar dipengaruhi oleh aspek kognitif dan rutinitas belajar. Kesimpulan yang diambil adalah: 1) Aspek kognitif berpengaruh terhadap prestasi belajar mata kuliah Hukum Pajak dan Perpajakan, dapat diterima. Hal ini berdasarkan analisis regresi linier berganda (uji t) diketahui bahwa thitung > ttabel, yaitu 2,628 > 1,979 dan nilai signifikansi ttabel, yaitu 2,120 > 1,979 dan nilai signifikansi < 0,05, yaitu 0,036, dengan sumbangan efektif sebesar 5,3%; 3) Aspek kognitif dan rutinitas belajar berpengaruh terhadap prestasi belajar mata kuliah Hukum Pajak dan Perpajakan, dapat diterima. Hal ini berdasarkan analisis variansi regresi linier berganda (uji F) diketahui bahwa Fhitung > Ftabel, yaitu 9,114 > 3,066 dan nilai signifikansi < 0,05, yaitu 0,000; 4) Hasil uji koefisien determinasi (R2) sebesar 0,124 menunjukkan bahwa besarnya pengaruh aspek kognitif dan rutinitas belajar terhadap prestasi belajar mata kuliah Hukum Pajak dan Perpajakan, adalah sebesar 12,4% sedangkan 87,6% sisanya dipengaruhi oleh variabel lain yang tidak diteliti