590 research outputs found

    Spectral splits of neutrinos as a BCS-BEC crossover type phenomenon

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    We show that the spectral split of a neutrino ensemble which initially consists of electron type neutrinos, is analogous to the BCS-BEC crossover already observed in ultra cold atomic gas experiments. Such a neutrino ensemble mimics the deleptonization burst of a core collapse supernova. Although these two phenomena belong to very different domains of physics, the propagation of neutrinos from highly interacting inner regions of the supernova to the vacuum is reminiscent of the evolution of Cooper pairs between weak and strong interaction regimes during the crossover. The Hamiltonians and the corresponding many-body states undergo very similar transformations if one replaces the pair quasispin of the latter with the neutrino isospin of the former.Comment: 9 pages, 5 figure

    Effect of Moisture Content on Thermal Properties of Pumpkin Seed

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    The selected thermal properties, namely specific heat, thermal conductivity and thermal diffusivity were determined for pumpkin seeds in the moisture content range of 5.32-24.00% (d.b.). Specific heat was determined using the method of mixtures. Thermal conductivity was measured by the transient technique using the line heat source method assembled in a thermal conductivity probe. Specific heat, thermal conductivity, and thermal diffusivity of pumpkin seeds were found between 2.53 and 3.13 kJ kg-1K-1, 0.113, and 0.135 W m-1K-1, 9.954 10-8 and 1.289 10-7 m2 s-1, respectively, under the conditions with by changing moisture content. Specific heat and thermal conductivity of pumpkin seeds increased with increasing moisture content, while thermal diffusivity decreased with the increase in moisture content

    ALKALİ KATALİZATÖRLÜ ORGANİK DELİGNİFİKASYON SİSTEMLERİ

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    Alkali kraft metodu, günümüzde dünya genelinde en çok kullanılan kimyasal kağıt hamuru üretimi prosesidir. Fakat bu metodun bir çok dezavantajı bulunmaktadır. Özellikle havayı, suyu ve çevreyi kirletme özelliğindeki kimyasal maddeler kullanılmakta, oldukça yüksek yatırım ve işletme maliyetini gerektirmektedir. Hernekadar bu problemlerin tamamı elimine edilemese bile bir kısmının çözülmesi mümkündür. Labaratuvar ortamında geliştirilen yeni delignifikasyon sistemlerinin birçok avantajı olduğuna inanılmaktadır. Bu çalışmada da, biyokütlenin deklignifikasyonunda kullanılmak üzere, alkalilerin organik çözeltilere eklenmesiyle geliştirilen metanolle güçlendirilmiş kraft, organocell ve IDE prosesleri incelenecektir. Anahtar Kelimeler: Alkalen delignifikasyon, Metanol-kraft, Kağıt hamuru, Organocell, IDE sistem

    Housing prices and transaction volume

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    We use annual, quarterly and monthly data from the US to show that the correlation between housing prices and transaction volume (number of existing houses sold) differs across different frequencies. While the correlation is high at low frequencies it declines to the levels close to zero at high frequencies. Granger causality tests for different frequencies show the way of causality in housing market goes from transactions to housing prices. Our findings provide a litmus test for the existing theories that are proposed to explain the positive correlation between housing prices and transaction volume

    Electromagnon dispersion probed by inelastic X-ray scattering in LiCrO2

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    Inelastic X-ray scattering with meV energy resolution (IXS) is an ideal tool to measure collective excitations in solids and liquids. In non-resonant scattering condition, the cross-section is strongly dominated by lattice vibrations (phonons). However, it is possible to probe additional degrees of freedom such as magnetic fluctuations that are strongly coupled to the phonons. The IXS spectrum of the coupled system contains not only the phonon dispersion but also the so far undetected magnetic correlation function. Here we report the observation of strong magnon-phonon coupling in LiCrO2 that enables the measurement of magnetic correlations throughout the Brillouin zone via IXS. We find electromagnon excitations and electric dipole active two-magnon excitations in the magnetically ordered phase and heavily damped electromagnons in the paramagnetic phase of LiCrO2. We predict that several (frustrated) magnets with dominant direct exchange and non-collinear magnetism show surprisingly large IXS cross-section for magnons and multi-magnon processes

    Magnetodielectric coupling and phonon properties of compressively strained EuTiO3 thin films deposited on LSAT

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    Compressively strained epitaxial (001) EuTiO3 thin films of tetragonal symmetry have been deposited on (001) (LaAlO3)_0.29-(SrAl_{1/2}Ta_{1/2}O3)_0.71 (LSAT) substrates by reactive molecular-beam epitaxy. Enhancement of the Neel temperature by 1 K with 0.9% compressive strain was revealed. The polar phonons ofthe films have been investigated as a function of temperature and magnetic field by means of infrared reflectance spectroscopy. All three infrared active phonons show strongly stiffened frequencies compared to bulk EuTiO3 in accordance with first principles calculations. The phonon frequencies exhibit gradual softening on cooling leading to an increase in static permittivity. A new polar phonon with frequency near the TO1 soft mode was detected below 150 K. The new mode coupled with the TO1 mode was assigned as the optical phonon from the Brillouin zone edge, which is activated in infrared spectra due to an antiferrodistortive phase transition and due to simultaneous presence of polar and/or magnetic nanoclusters. In the antiferromagnetic phase we have observed a remarkable softening of the lowest-frequency polar phonon under an applied magnetic field, which qualitatively agrees with first principles calculations. This demonstrates the strong spin-phonon coupling in EuTiO3, which is responsible for the pronounced dependence of its static permittivity on magnetic field in the antiferromagnetic phase.Comment: Submitted to Phys. Rev.

    Peningkatan Nilai Kalori pada Batubara Lignit dengan Metode Aglomerasi Air dan Minyak Sawit pada PT. Indonesia Power Ujp Pltu Barru

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    Penggunaan batubara di PLTU sangat bergantung kepada kualitas batubara yang digunakan, karena semakin tinggi kualitas batubara maka akan memaksimalkan pembakaran dan secara langsung akan berdampak pada produksi listrik yang dihasilkan. Penelitian ini bertujuan untuk mengetahui peningkatan nilai kalori pada batubara lignit. Pada penelitian ini digunakan metode aglomerasi dengan media air dan minyak sawit yang pada setiap sampel diberi perlakukan yang sama namun mengalami peningkatan yang berbeda. Ada tiga sampel yang digunakan pada penelitian ini dimana pada setiap sampel memiliki komposisi batubara lignit seberat 1 gram, minyak sawit sebanyak 10,20,30 ml dan air sebanyak 100 ml. Hasil penelitian ini menunjukkan bahwa semakin banyak konsentrasi minyak maka semakin tinggi kadar karbon yang diikat, sehingga dapat meningkatkan nilai kalori batubara. Dilihat dari konsentrasi 30% pada setiap sampel batubara mengalami peningkatan nilai kalori yang sebelumnya 3.765,23 cal/gr menjadi 5.279,46 cal/gr pada sampel pertama, 3.567,44 cal/gr menjadi 4.989,07 cal/gr pada sampel kedua dan 4.026,07 cal/gr menjadi 5.166,98 cal/gr pada sampel ketiga. Dari hasil penelitian ini dapat disimpulkan bahwa batubara lignit yang digunakan di PLTU dapat ditingkatkan nilai kalorinya menggunakan metode aglomerasi air dan minyak sawit

    Microstructural evolution under low shear rates during Rheo processing of LM25 alloy

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    © ASM InternationalMicrostructural features of LM25 alloy processed by two different routes: (1) conventional casting, and(2)shear casting based on inclined heated surface are studied. The microstructures of the primary phase for the shear-cast samples show rosette or ellipsoidal morphologies. Heat transfer of contacting melt with the inclined tube surface and shear stress exerted on the layers of the melt as result of gravitational force are crucial parameters for the microstructural evolution. Compared to those produced by conventional casting, shear-cast samples have a much improved tensile strength and ductility due to globular microstructure
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