Термохімічні властивості рідких сплавів заліза з важкими лантаноїдами: експеримент та моделювання

Ентальпії змішування в рідких сплавах заліза із важкими лантаноїдами (Gd, Tb, Dy та Lu) визначено при 1550–1950 K методом високотемпературної калориметрії в ізопериболічному режимі. Процес сплавоутворення супроводжується екзотермічними ефектами, які зростають вздовж ряду лантанідів від системи Fe–Gd ( ΔmHmin = –4.74 ± 0.45 кДж ·моль⁻¹ при Gd x = 0.45; T = 1833 K) до системи Fe–Lu ( ΔmHmin = –11.58 ± 0.50 кДж ·моль⁻¹ при Lu x = 0.35; T = 1950 K). Ентальпії змішування, змодельовані з використанням теорії «оточеного атому» для розплавів всіх досліджених подвійних систем, узгоджуються з отриманими експериментально в межах похибки досліду.Энтальпии смешения в жидких сплавах железа с тяжелыми лантаноидами (Gd, Tb, Dy и Lu) определены при 1550–1950 K методом высокотемпературной калориметрии в изопериболическом режиме. Процесс сплавообразования сопровождается экзотермическими эффектами, возрастающими вдоль ряда лантаноидов от системы Fe–Gd ( ΔmHmin = –4,74 ± 0,40 кДж ∙ моль⁻¹ при Gd x = 0,45; T = 1833 K) до системы Fe–Lu ( ΔmHmin = –11,58 ± 0,50 кДж ∙ моль⁻¹ при Lu x = 0,35; T = 1950 K). Энтальпии смешения, смоделированные с использованием теории “окруженного атома” для расплавов всех исследованных двойных систем, согласуются с полученными экспериментально в пределах ошибки опыта.The enthalpies of mixing in liquid alloys of iron with the heavy lanthanides (Gd, Tb, Dy and Lu) were determined at 1550–1950 K by high temperature izoperibolic calorimetry. The process of alloy formation was accompanied with exothermic effects, increasing across the lanthanides row from the Fe–Gd system ( ΔmHmin = –4.74 ± 0.40 kJ ∙ mol⁻¹ at Gd x = 0.45; T = 1833 K) to Fe–Lu system (ΔmHmin = –11.58 ± 0.50 kJ ∙ mol⁻¹ at Lu x = 0.35; T = 1950 K). Enthalpies of mixing, calculated by using of “surrounded atom” theory for alloys of all investigated binary systems, agree with experimental values within errors limits

On periodic boundary value problem for the Sturm-Liouville operator

We consider the Sturm-Liouville operator Lu=u''-q(x)u with periodic or antiperiodic boundary conditions. It is shown that depending of Fourier coefficients of the potential q(x) the system of root functions may have or may not have the basis property.Comment: Published in Proceedings of the International Conference "Function Spaces, Approximation Theory, Nonlinear Analysis", Moscow, Russia, May 23-29, 2005, p. 14

Analisa Numerik Efek Ketebalan Bluff Rectangular Terhadap Karakteristik Aliran Di Dekat Dinding

Bluff rectangular is one of turbulator which has function as flow disturbance. |The disturbance will be usefull and it becomes the trigger to accelerate flow transition from laminar and turbulent flow. However the disturbance could destroy the flow. It depends on the thickness of bluff rectangular. This research focused on the effect caused by the thickness of bluff rectangular toward the surrounding flow. The thickness variant which will investigate is 0.025d/Lu,0.0375d/Lu , 0.05d/Lu ,0.075d/Lu and 0.1d/Lu. This research utilize numerical analyze only when using Computation Fluid Dynamic method. In the simulation with free stream flow Red =103 based on bluff rectangular body thickness (d) on steady state condition and turbulent viscous model used Shear Stress Transport k-Omega. Numerical result shown that bubble separation flow will not occur by using bluff rectangular with 0.025d/Lu ,where it is not as for other thinckness. Especially for bluff rectangular by 0.0375d/Lu occur delayed bubble separation which lie x=1.5d after bluff rectangular point, whereas for 0.05d/Lu ,0.075d/Lu and 0.1d/Lu bubble separation lie right behind bluff rectangular. For bubble separation which occured is inversely linear with the bluff rectangular thickness. velocity profile occured on x=4Lu shown should 0.075d/Lu and 0.1d/Lu bluff rectangular has higher velocity near the wall especially y/δ < 0.1. The smallest shape factor produced by 0.075d/Lu bluff rectangular hence it is stated as the best turbulator

Penampilan Karakter Produksi Kacang Panjang (Vigna Sinensis L.) Generasi F1 dan Tetuanya

Kacang panjang sering dikonsumsi masyarakat sehingga permintaan ketersediaanya sangat tinggi, USAha yang dilakukan untuk meningkatkan produksi kacang panjang adalah dengan memperoleh varietas yang memiliki sifat unggul dengan produksi tinggi.Penelitian ini bertujuan untuk membandingkan karakter produksi hasil persilangan Hitam x Lurik dan Lurik x Hitam dengan tetuanya dan produksi hasil persilangan resiprok yaitu Hitam x Lurik dengan Lurik x Hitam. Benih yang digunakan adalah benih Hitam, Lurik, Hitam x Lurik dan Lurik Hitam.Perlakuan disusun dalam Rancangan Acak Lengkap (RAL) dan data diuji dengan uji LSI dan heterosis.Hasil penelitian dengan uji LSI menunjukkan bahwa pada karakter produksi hanya panjang polong zuriat Lu x Hi yang lebih baik dari kedua tetuanya. Nilai duga heterosis menunjukkan bahwa karakter produksi zuriat Hi x Lu yang memiliki efek heterosis dan heterobeltiosis yaitu pada karakter jumlah dan bobot polong sedangkan pada zuriat Lu x Hi hanya karakter panjang polong yang mengalami efek heterosis dan heterobeltiosis

Representing fuzzy numbers for fuzzy calculus

In this paper we illustrate the LU representation of fuzzy numbers and present an LU-fuzzy calculator, in order to explain the use of the LU-fuzzy model and to show the advantage of the parametrization. The model can be applied either in the level-cut or in generalized LR frames. The hand-like fuzzy calculator has been developed for the MSWindows platform and produces the basic fuzzy calculus: the arithmetic operations (scalar multiplication, addition, subtraction, multiplication, division) and the fuzzy extension of many univariate functions (exponential, logarithm, power with numeric or fuzzy exponent, sin, arcsin, cos, arccos, tan, arctan, square root, Gaussian, hyperbolic sinh, cosh, tanh and inverses, erf and erfc error functions, cumulative standard normal distribution).Fuzzy Sets, LU-fuzzy Calculator, Fuzzy Calculus, Parametric LU represemtation

Evolution of a metastable phase with a magnetic phase coexistence phenomenon and its unusual sensitivity to magnetic field cycling in the alloys Tb5-xLuxSi3 (x <= 0.7)

Recently, we reported an anomalous enhancement of the positive magnetoresistance beyond a critical magnetic field in Tb5Si3 in the magnetically ordered state, attributable to 'inverse metamagnetism'. This results in unusual magnetic hysteresis loops for the pressurized specimens, which are relevant to the topic of 'electronic phase separation'. In this paper, we report the influence of small substitutions of Lu for Tb, to show the evolution of these magnetic anomalies. We find that, at low temperatures, the high-field high-resistivity phase could be partially stabilized on returning the magnetic field to zero in many of these Lu substituted alloys, as measured through the electrical resistivity ({\rho}). Also, the relative fractions of this phase and the virgin phase appear to be controlled by a small tuning of the composition and temperature. Interestingly, at 1.8 K a sudden 'switch-over' of the value of {\rho} for this mixed phase to that for the virgin phase for some compositions is observed at low fields after a few field cycles, indicating metastability of this mixed phase