Abstract: Inthis paper, design and fabrication of vertical
micromirror for optical switching applications of single mode optical
fibers are proposed. The structure of micromirror will be created
from negative photoresist (SU-8) on X-ray lithography using X-ray
from synchrotron light source. The properties of X-ray from
synchrotron light source are high-energy electrons which can
construct materials that have a high aspect ratio. In addition, the
technique of gold coating of reflective material has been used for
change direction of light between two pairs of optical fibers. At a
wavelength of 1310 nm with minimum average loss of 5.305 dB is
obtained.
Abstract: A self-association model has been used to understand
the concentration dependence of free energy of mixing (GM), heat of
mixing (HM), entropy of mixing (SM), activity (a) and microscopic
structures, such as concentration fluctuation in long wavelength limit
(Scc(0)) and Warren-Cowley short range order parameter ( 1
α )for Cu-
Tl molten alloys at 1573K. A comparative study of surface tension of
the alloys in the liquid state at that temperature has also been carried
out theoretically as function of composition in the light of Butler-s
model, Prasad-s model and quasi-chemical approach. Most of the
computed thermodynamic properties have been found in agreement
with the experimental values. The analysis reveals that the Cu-Tl
molten alloys at 1573K represent a segregating system at all
concentrations with moderate interaction. Surface tensions computed
from different approaches have been found to be comparable to each
other showing increment with the composition of copper.
Abstract: The bridge vibration due to traffic loading has been a
subject of extensive research during the last decades. A number of
these studies are concerned with the effects of the unevenness of
roadways on the dynamic responses of highway bridges. The road
unevenness is often described as a random process that constitutes
of different wavelengths. Thus, the study focuses on examining
the effects of the random description of roadways on the dynamic
response and its variance. A new setting of variance based sensitivity
analysis is proposed and used to identify and quantify the
contributions of the roadway-s wavelengths to the variance of the
dynamic response. Furthermore, the effect of the vehicle-s speed on
the dynamic response is studied.
Abstract: Semiconductor materials with coatings have a wide range of applications in MEMS and NEMS. This work uses transfermatrix method for calculating the radiative properties. Dopped silicon is used and the coherent formulation is applied. The Drude model for the optical constants of doped silicon is employed. Results showed that for the visible wavelengths, more emittance occurs in greater concentrations and the reflectance decreases as the concentration increases. In these wavelengths, transmittance is negligible. Donars and acceptors act similar in visible wavelengths. The effect of wave interference can be understood by plotting the spectral properties such as reflectance or transmittance of a thin dielectric film versus the film thickness and analyzing the oscillations of properties due to constructive and destructive interferences. But this effect has not been shown at visible wavelengths. At room temperature, the scattering process is dominated by lattice scattering for lightly doped silicon, and the impurity scattering becomes important for heavily doped silicon when the dopant concentration exceeds1018cm-3 .
Abstract: Group-III nitride material as particularly AlxGa1-xN is
one of promising optoelectronic materials to require for shortwavelength
devices. To achieve the high-quality AlxGa1-xN films for
a high performance of such devices, AlN-nucleation layers are the
important factor. To improve the AlN-nucleation layers with a
variation of Ga-addition, XRD measurements were conducted to
analyze the crystalline quality of the subsequent Al0.1Ga0.9N with the
minimum ω-FWHMs of (0002) and (10-10) reflections of 425 arcsec
and 750 arcsec, respectively. SEM and AFM measurements were
performed to observe the surface morphology and TEM
measurements to identify the microstructures and orientations.
Results showed that the optimized Ga-atoms in the Al(Ga)Nnucleation
layers improved the surface diffusion to form moreuniform
crystallites in structure and size, better alignment of each
crystallite, and better homogeneity of island distribution. This, hence,
improves the orientation of epilayers on the Si-surface and finally
improves the crystalline quality and reduces the residual strain of
subsequent Al0.1Ga0.9N layers.
Abstract: A general stochastic spatial MIMO channel model is
proposed for evaluating various MIMO techniques in this paper. It can
generate MIMO channels complying with various MIMO
configurations such as smart antenna, spatial diversity and spatial
multiplexing. The modeling method produces the stochastic fading
involving delay spread, Doppler spread, DOA (direction of arrival),
AS (angle spread), PAS (power azimuth Spectrum) of the scatterers,
antenna spacing and the wavelength. It can be applied in various
MIMO technique researches flexibly with low computing complexity.
Abstract: This paper presents a new heuristic algorithm useful
for long-term planning of survivable WDM networks. A multi-period
model is formulated that combines network topology design and
capacity expansion. The ability to determine network expansion
schedules of this type becomes increasingly important to the
telecommunications industry and to its customers. The solution
technique consists of a Genetic Algorithm that allows generating
several network alternatives for each time period simultaneously and
shortest-path techniques to deduce from these alternatives a least-cost
network expansion plan over all time periods. The multi-period
planning approach is illustrated on a realistic network example.
Extensive simulations on a wide range of problem instances are
carried out to assess the cost savings that can be expected by
choosing a multi-period planning approach instead of an iterative
network expansion design method.
Abstract: Recently, as information industry and mobile
communication technology are developing, this study is conducted on
the new concept of intelligent structures and maintenance techniques
that applied wireless sensor network, USN (Ubiquitous Sensor
Network), to social infrastructures such as civil and architectural
structures on the basis of the concept of Ubiquitous Computing that
invisibly provides human life with computing, along with mutually
cooperating, compromising and connecting networks each other by
having computers within all objects around us.
Therefore, the purpose of this study is to investigate the capability
of wireless communication of sensor node embedded in reinforced
concrete structure with a basic experiment on an electric wave
permeability of sensor node by fabricating molding with variables of
concrete thickness and steel bars that are mostly used in constructing
structures to determine the feasibility of application to constructing
structures with USN.
At this time, with putting the pitches of steel bars, the thickness of
concrete placed, and the intensity of RF signal of a
transmitter-receiver as variables and when wireless communication
module was installed inside, the possible communication distance of
plain concrete and the possible communication distance by the pitches
of steel bars was measured in the horizontal and vertical direction
respectively. Besides, for the precise measurement of diminution of an
electric wave, the magnitude of an electric wave in the range of used
frequencies was measured by using Spectrum Analyzer. The
phenomenon of diminution of an electric wave was numerically
analyzed and the effect of the length of wavelength of frequencies was
analyzed by the properties of a frequency band area.
As a result of studying the feasibility of an application to
constructing structures with wireless sensor, in case of plain concrete,
it shows 45cm for the depth of permeability and in case of reinforced
concrete with the pitches of 5cm, it shows 37cm and 45cm for the
pitches of 15cm.
Abstract: We demonstrate a 1×4 coarse wavelength
division-multiplexing (CWDM) planar concave grating
multiplexer/demultiplexer and its application in re-configurable
optical add/drop multiplexer (ROADM) system in silicon-on-insulator
substrate. The wavelengths of the demonstrated concave grating
multiplexer align well with the ITU-T standard. We demonstrate a
prototype of ROADM comprising two such concave gratings and four
wide-band thermo-optical MZI switches. Undercut technology which
removes the underneath silicon substrate is adopted in optical switches
in order to minimize the operation power. For all the thermal heaters,
the operation voltage is smaller than 1.5 V, and the switch power is
~2.4 mW. High throughput pseudorandom binary sequence (PRBS)
data transmission with up to 100 Gb/s is demonstrated, showing the
high-performance ROADM functionality.