Gas-discharge XeF* (B→X) laser with high specific output energy

The discharge characteristics of the XeF* (B→X) laser are investigated. The NF3 and Xe partial pressure of the laser gas mixture and the total gas pressure have been varied. A highest specific output energy of 4.7 J/l with an efficiency of 0.5% was obtained from a X-ray preionized Ne/Xe/NF3 gas mixture at 6 bar with single-pulse excitation through a multichannel spark gap

The Implementation of Task-based Learning in Teaching Recount Text Writing for Junior High School Students

Penelitian ini menelaah cara guru dalam menerapkan pembelajaran berbasis tugas dalam pengajaran menulis melalui beberapa langkah dan menjelaskan bagaimana kemampuan siswa dalam menulis teks recount. Penelitian ini dilakukan dengan pendekatan kualitatif karena hasil data dianalisis dan dideskripsikan dalam bentuk kata- kata, kalimat, dan ujaran. Data diperoleh dari observasi, wawancara, dan tulisan siswa. Analisis data dilakukan melalui kategorisasi, displai data dan pengambilan kesimpulan. Subjek penelitian ini adalah seorang guru Bahasa Inggris dan tiga puluh siswa kelas 8. Hasil penelitian menunjukkan bahwa penerapan pembelajaran berbasis tugas memiliki banyak kelemahan dalam beberapa aspek, diantaranya adalah tidak lengkapnya langkah- langkah dalam pelaksanaan pada saat penerapan, kekurangan waktu pada saat mengerjakan tugas dan juga penggunaan bahasa ibu dan bukannya bahasa target oleh siswa yang membuat penerapan pembelajaran berbasis tugas tidak berhasil seperti yang diharapkan. Berdasarkan temuan tersebut, beberapa saran diajukan. Guru Bahasa Inggris seharusnya menggunakan dan mendesain tugas yang tidak memakan waktu lama dalam pengerjaannya, sehingga langkah- langkah dalam pembelajaran berbasis tugas ini dapat terlaksana dalam satu pertemuan. Para siswa harus berbicara menggunakan bahasa target ketika pembelajaran berbasis tugas ini diterapkan agar tujuan pendekatan ini dapat tercapai

Atmospheric Charged K/πK/\pi Ratio and Measurement of Muon Annual Modulation with a Liquid Scintillation Detector at Soudan

We report a measurement of muon annual modulation in a 12-liter liquid scintillation detector with a live-time of more than 4 years at the Soudan Underground Laboratory. Muon minimum ionization in the detector is identified by its observed pulse shape and large energy deposition. The measured muon rate in the detector is 28.69$\pm$2.09 muons per day with a modulation amplitude of 2.66$\pm$ 1.0\% and a phase at Jul 22 $\pm$ 36.2 days. This annual modulation is correlated with the variation of the effective atmospheric temperature in the stratosphere. The correlation coefficient, $\alpha_{T}$, is determined to be $0.898 \pm 0.025$. This can be interpreted as a measurement of the atmospheric charged kaon to pion ($K$/$\pi$) ratio of 0.094$^{+0.044}_{-0.061}$ for $E_{p} >$ 7 TeV, consistent with the measurement from the MINOS far detector. To further constrain the value of $K$/$\pi$ ratio, a Geant4 simulation of the primary cosmic-ray protons with energy up to 100 TeV is implemented to study the correlation of $K$/$\pi$ ratio and the muon annual modulation for muon energy greater than 0.5 TeV. We find out that a charged $K$/$\pi$ ratio of 0.1598, greater than the upper bound (0.138) from this work at the production point 30 km above the Earth surface in the stratosphere cannot induce muon annual modulation at the depth of Soudan.Comment: 6 pages and 11 figure

Construction and Refinement of Coarse-Grained Models

A general scheme, which includes constructions of coarse-grained (CG) models, weighted ensemble dynamics (WED) simulations and cluster analyses (CA) of stable states, is presented to detect dynamical and thermodynamical properties in complex systems. In the scheme, CG models are efficiently and accurately optimized based on a directed distance from original to CG systems, which is estimated from ensemble means of lots of independent observable in two systems. Furthermore, WED independently generates multiple short molecular dynamics trajectories in original systems. The initial conformations of the trajectories are constructed from equilibrium conformations in CG models, and the weights of the trajectories can be estimated from the trajectories themselves in generating complete equilibrium samples in the original systems. CA calculates the directed distances among the trajectories and groups their initial conformations into some clusters, which correspond to stable states in the original systems, so that transition dynamics can be detected without requiring a priori knowledge of the states.Comment: 4 pages, no figure

Modal Analysis of Grid Connected Doubly-Fed Induction Generators

This paper presents the modal analysis of a gridconnected doubly fed induction generator (DFIG). The change in modal properties for different system parameters, operating points, and grid strengths are computed and observed. The results offer a better understanding of theDFIG intrinsic dynamics,which can also be useful for control design and model justification. Index Terms—Doubly fed induction generator, eigenvalue analysis, nonlinear dynamic model, small-signal stability.Published versio