DSpace Collection:http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/892026-05-17T20:58:37Z2026-05-17T20:58:37ZDevelopment of a spectrometry system using lock-in amplification techniqueNguyen, The BinhNguyen, Huy BinhNguyen, Anh Tuanhttp://tainguyenso.vnu.edu.vn/jspui/handle/123456789/4752011-04-18T09:16:16Z2005-01-01T00:00:00ZTitle: Development of a spectrometry system using lock-in amplification technique
Authors: Nguyen, The Binh; Nguyen, Huy Binh; Nguyen, Anh Tuan
Abstract: Raman spectroscopy and optical second-harmonic (SH) spectroscopy
has a very important role in studies of optical properties of materials. Our goal
is to build a spectrometry system to measure weak optical signals such as
Raman scattering and surface SH signals. We studied to improve an old Double
Grating Spectrograph GDM-1000 (Carl Zeiss, Jena, Germany) for wider range
of wavelengths and transformed it successfully into a spectrometry system
coupling with computer using Lock-in amplification technique. By this
spectrometry system we can now obtain weak optical signals, for example,
Raman Spectra of Vietnam petrol extracts excited by not only an 2W Argon
laser but also by a 30mW He-Ne laser.
Description: VNU. JOURNAL OF SCIENCE, Mathematics - Physics, Vol. 21, No. 2, 20052005-01-01T00:00:00ZSingularity of Fractal Measure Associated with The $(0, 1, 7)$ - ProblemTruong, Thi Thuy DuongVu, Hong Thanhhttp://tainguyenso.vnu.edu.vn/jspui/handle/123456789/4742011-04-18T09:10:48Z2005-01-01T00:00:00ZTitle: Singularity of Fractal Measure Associated with The $(0, 1, 7)$ - Problem
Authors: Truong, Thi Thuy Duong; Vu, Hong Thanh
Abstract: Let μ be the probability measure induced by S =
∞n
=1 3−nXn, where
X1,X2, ... is a sequence of independent, identically distributed (i.i.d) random variables
each taking values 0, 1, a with equal probability 1/3. Let α(s) (resp.α(s), α(s)) denote
the local dimension (resp. lower, upper local dimension) of s ∈ supp μ, and let
α = sup{α(s) : s ∈ supp μ}; α = inf{α(s) : s ∈ supp μ};
E = {α : α(s) = α for some s ∈ supp μ}
.
In the case a = 3k +1 for k = 1, E = [1 − log(1+√5)−log 2
log 3 , 1], see [10]. It is conjectured
that in the general case, for a = 3k + 1 ( k ∈ N), the local dimension is of the form as
the case k = 1, i.e., E = [1 − log a
b log 3 , 1] for a, b depends on k. In fact, our result shows
that for k = 2 (a = 7), we have α = 1, α = 1− log(1+√3)
3 log 3 and E = [1 − log(1+√3)
3 log 3 , 1].
Description: VNU. JOURNAL OF SCIENCE, Mathematics - Physics. Vol. 21,No. 2 - 20052005-01-01T00:00:00ZFabrication of high-aspect-ratio micro structures using uv-liga technologyNguyen, Thi Minh HangChien-Hung, HoVu, Ngoc HungNguyen, Phu Thuyhttp://tainguyenso.vnu.edu.vn/jspui/handle/123456789/4702011-04-18T09:07:55Z2005-01-01T00:00:00ZTitle: Fabrication of high-aspect-ratio micro structures using uv-liga technology
Authors: Nguyen, Thi Minh Hang; Chien-Hung, Ho; Vu, Ngoc Hung; Nguyen, Phu Thuy
Abstract: Thanks to almost transparent property of SU8 for wavelength of 365-
400nm, UV-LIGA technology using this photoresist has been applied to fabricate
high-aspect-ratio (HAR) microstructures. This allows transferring patterns with
vertical sidewall from masks to the photoresist. This paper introduces UV-LIGA
and its application in fabricating comb drive structure for an angular rate sensor of
linewidth and thickness of 50μm and 120μm, respectively.
Description: VNU. JOURNAL OF SCIENCE, Mathematics - Physics, Vol. 21 , No. 2, 20052005-01-01T00:00:00ZCorrelation Effects in Atomic Thermal Vibration of fcc CrystalsNguyen, Van Hunghttp://tainguyenso.vnu.edu.vn/jspui/handle/123456789/4672011-04-18T09:01:34Z2005-01-01T00:00:00ZTitle: Correlation Effects in Atomic Thermal Vibration of fcc Crystals
Authors: Nguyen, Van Hung
Abstract: Analytical expression for the Displacement-displacement Correlation
Function (DCF) CR has been derived based on the derived Mean Square Relative
Displacement (MSRD) σ2 and the Mean Square Displacement (MSD) u2 for fcc
crystals. The effective interaction potential of the system has been considered by
taking into account the influences of nearest atomic neighbors, and it contains the
Morse potential characterizing the interaction of each pair of atoms. Numerical
calculations have been carried out for u2 , σ2 and CR functions of Cu and Ni. The
ratio CR /u2 is 40% and CR / σ2 25% at high temperatures. They are found to be in
good agreement with experiment and with those calculated by the Debye model.
Description: VNU. JOURNAL OF SCIENCE, Mathematics - Physics, Vol. 21, No. 2, 20052005-01-01T00:00:00Z