http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/104 2026-05-17T16:10:18Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/820 Title: An application of random process for controlled object identification with traffic delay problem Authors: Vu, Tien Viet Abstract: In the article proposed an effective method estimating transfer function model of controlled plant including dead-time delay, based on stochatstic time series of input-output signals. The model structure is modified with parameters optimized until the model error becomes "white-noise" series that with inough smal auto-correlation function. Description: VNU Journal of Science, Mathematics - Physics. Vol. 24 (2008), No 2 (M.P), P. 101-109 2008-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/816 Title: Thermoluminescence properties of Li2B4O7:Cu material Authors: Ngo, Quang Thanh; Vu, Xuan Quang; Nguyen, The Khoi; Nguyen, Dac Dien Abstract: The copper-doped lithium tetraborate Li2B4O7:Cu (LBCu) is one of the famous tissue equivalent materials for the thermoluminescent dosimetry, very useful for applications in medical and personal dosimetry measurements. This material in powder and pellet forms was prepared by sintering method in the Laboratory of Applied Spectroscopy and Gemology- IMS-VAST. In this study the dosimetric characteristics of LBCu powder were examined: ho- mogeneity of batch, reproducibility, dose response and evaluation kinetic parameters. Description: VNU Journal of Science, Mathematics - Physics. Vol. 24 (2008), No 2 (M.P), P. 97-100 2008-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/813 Title: Wavelength shift in microsphere lasers Authors: Tran, Thi Tam; Dang, Quoc Trung; Tran, Anh Vu; Le, Huu Minh; Do, Ngoc Chung Abstract: The wavelength shift effect of the Whispering Gallery Mode (WGM) laser with Er3+/Yb3+ co-doped phosphate glass microsphere has been investigated. The experiment was carried out by half fiber taper coupling technique. The microsphere lasers have been pumped at 980 nm to take full advantage of energy transfer effect from ion Ytterbium to ion Erbium. The WGM’s wavelength shift were analyzed for sphere diameters of 90 μm. The observed lasing lines extends from 1532 nm to 1611 nm. Description: VNU Journal of Science, Mathematics - Physics. Vol. 24 (2008), No 2 (M.P), P. 89-96 2008-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/810 Title: Determination of the 15 MeV bremsstrahlung spectrum from thin W target on the microtron MT-17 accelerator Authors: Pham, Duc Khue; Bui, Van Loat Abstract: Bremsstrahlung energy spectrum from thin W target produced by 15 MeV incident electrons was determined by a combination of measurements and theoretical calculation. The shape of spectrum was calculated by Monte-Carlo method using the code EGS4. The photon flux measurements were performed based on the activation technique using the high pure metallic foils. The radioactivities of the irradiated foils were measured by using a gamma spectrometer with a high energy resolution HPGe detector. The experiments were carried out at the 15 MeV electron Microtron MT-17 accelerator located at Institute of Physics and Electronics, Hanoi. Description: VNU Journal of Science, Mathematics - Physics. Vol. 24 (2008), No 2 (M.P), P. 81-87 2008-01-01T00:00:00Z