Abstract: This work presents the mixed-mode II/III prestressed split-cantilever beam specimen for the fracture testing of composite materials. In accordance with the concept of prestressed composite beams one of the two fracture modes is provided by the prestressed state of the specimen, and the other one is increased up to fracture initiation by using a testing machine. The novel beam-like specimen is able to provide any combination of the mode-II and mode-III energy release rates. A simple closed-form solution is developed using beam theory as a data reduction scheme and for the calculation of the energy release rates in the new configuration. The applicability and the limitations of the novel fracture mechanical test are demonstrated using unidirectional glass/polyester composite specimens. If only crack propagation onset is involved then the mixed-mode beam specimen can be used to obtain the fracture criterion of transparent composite materials in the GII - GIII plane in a relatively simple way.
Abstract: Films of pure tin oxide SnO2 and in presence of
antimony atoms (SnO2-Sb) deposited onto glass substrates have
shown a sufficiently high energy gap to be transparent in the visible
region, a high electrical mobility and a carrier concentration which
displays a good electrical conductivity [1]. In this work, the effects of
polycrystalline silicon substrate on the optical properties of pure and
Sb doped tin oxide is investigated.
We used the APCVD (atmospheric pressure chemical vapour
deposition) technique, which is a low-cost and simple technique,
under nitrogen ambient, for growing this material. A series of SnO2
and SnO2-Sb have been deposited onto polycrystalline silicon
substrates with different contents of antimony atoms at the same
conditions of deposition (substrate temperature, flow oxygen,
duration and nitrogen atmosphere of the reactor). The effect of the
substrate in terms of morphology and nonlinear optical properties,
mainly the reflectance, was studied. The reflectance intensity of the
device, compared to the reflectance of tin oxide films deposited
directly on glass substrate, is clearly reduced on the overall
wavelength range. It is obvious that the roughness of the poly-c
silicon plays an important role by improving the reflectance and
hence the optical parameters.
A clear shift in the minimum of the reflectance upon doping level
is observed. This minimum corresponds to strong free carrier
absorption, resulting in different plasma frequency. This effect is
followed by an increase in the reflectance depending of the antimony
doping. Applying the extended Drude theory to the combining
optical and electrical obtained results these effects are discussed.
Abstract: Physical and mechanical properties of Russian olive
fruits were measured at moisture content of 14.43% w.b. The results
revealed that the mean length, width and thickness of Russian olive
fruits were 20.72, 15.73 and 14.69mm, respectively. Mean mass and
volume of Russian olive fruits were measured as 1.45 g and 2.55 cm3,
respectively. The sphericity, aspect ratio and surface area were
calculated as 0.81, 0.72 and 8.96 cm2, respectively, while arithmetic
mean diameter, geometric mean diameter and equivalent diameter of
Russian olive fruits were 17.05, 16.83 and 16.84 mm, respectively.
Whole fruit density, bulk density and porosity of jujube fruits were
measured and found to be 1.01 g/cm3, 0.29 g/cm3 and 69.5%,
respectively. The values of static coefficient of friction on three
surfaces of glass, galvanized iron and plywood were 0.35, 0.36 and
0.43, respectively. The skin color (L*, a*, b*) varied from 9.92 to
16.08; 2.04 to 3.91 and 1.12 to 3.83, respectively. The values of
rupture force, deformation, energy absorbed and hardness were found
to be between 12.14-16.85 N, 2.16-4.25 mm, 3.42-6.99 N mm and
17.1-23.85 N/mm.
Abstract: The paper presents the brief information on particular results of experimental study focused to the problems of behavior of structural plated components made of fiber-cement-based materials and used in building constructions, exposed to atmospheric physical effects given by the weather changes in the summer period. Weather changes represented namely by temperature and rain cause also the changes of the temperature and moisture of the investigated structural components. This can affect their static behavior that means stresses and deformations, which have been monitored as the main outputs of tests performed. Experimental verification is based on the simulation of the influence of temperature and rain using the defined procedure of warming and water sprinkling with respect to the corresponding weather conditions during summer period in the South Moravian region at the Czech Republic, for which the application of these structural components is mainly planned. Two types of components have been tested: (i) glass-fiber-concrete panels used for building façades and (ii) fiber-cement slabs used mainly for claddings, but also as a part of floor structures or lost shuttering, and so on.
Abstract: We successfully developed a new straw combustion
technology that efficiently reduces problems with unmanageable deposits inside straw fueled boilers in Zluticka Heating Plant. The
deposits are mainly created by glass-forming melts. We plotted straw compositions in K2O-CaO-SiO2 phase diagram and illustrated
they are in the area of low-melting eutectic poi
melting of ash and the formation of deposits
compositions by injecting additives into biomass fuel
ueled points. To prevent the
deposits, we modified ash
fuel.
Abstract: The crystallization kinetics and phase transformation
of SiO2.Al2O3.0,56P2O5.1,8CaO.0,56CaF2 glass have been
investigated using differential thermal analysis (DTA), x-ray
diffraction (XRD), and scanning electron microscopy (SEM). Glass
samples were obtained by melting the glass mixture at 14500С/120
min. in platinum crucibles. The mixture were prepared from
chemically pure reagents: SiO2, Al(OH)3, H3PO4, CaCO3 and CaF2.
The non-isothermal kinetics of crystallization was studied by
applying the DTA measurements carried out at various heating rates.
The activation energies of crystallization and viscous flow were
measured as 348,4 kJ.mol–1 and 479,7 kJ.mol–1 respectively. Value of
Avrami parameter n ≈ 3 correspond to a three dimensional of crystal
growth mechanism. The major crystalline phase determined by XRD
analysis was fluorapatite (Ca(PO4)3F) and as the minor phases –
fluormargarite (CaAl2(Al2SiO2)10F2) and vitlokite (Ca9P6O24). The
resulting glass-ceramic has a homogeneous microstructure, composed
of prismatic crystals, evenly distributed in glass phase.
Abstract: Some physical properties of musk lime (Citrus
microcarpa) were determined in this study. The average moisture
content (wet basis) of the fruit was found to be 85.10 (±0.72) %. The
mean of length, width and thickness of the fruit was 26.36 (±0.97),
26.40 (±1.04) and 25.26 (±0.94) mm respectively. The average value
for geometric mean diameter, sphericity, aspect ratio, mass, surface
area, volume, true density, bulk density and porosity was 26.00
(±0.82) mm, 98.67 (±2.04) %, 100.23 (±3.28) %, 10.007 (±0.878) g,
2125.07 (±133.93) mm2, 8800.00 (±731.82) mm3, 1002.87 (±39.16)
kgm-3, 501.70 (±22.58) kgm-3 and 49.89 (±3.15) % respectively.
The coefficient of static friction on four types of structural surface
was found to be varying from 0.238 (±0.025) for glass to 0.247
(±0.024) for steel surface.
Abstract: This paper demonstrates the feasibility of replacing
the metal coil spring with the composite coil spring. Three different
types of springs were made using glass fiber, carbon fiber and
combination of glass fiber and carbon fiber. The objective of the
study is to reduce the weight of the spring. According to the
experimental results the spring rate of the carbon fiber spring is
34% more than the glass fiber spring and 45% more than the glass
fiber/carbon fiber spring. The weight of the carbon fiber spring is
18% less than the glass fiber spring, 15% less than the Glass
fiber/carbon fiber spring and 80% less than the steel spring.
Abstract: One of the most important problems to solve is eye
location for a driver fatigue monitoring system. This paper presents an
efficient method to achieve fast and accurate eye location in grey level
images obtained in the real-word driving conditions. The structure of
eye region is used as a robust cue to find possible eye pairs. Candidates
of eye pair at different scales are selected by finding regions which
roughly match with the binary eye pair template. To obtain real one,
all the eye pair candidates are then verified by using support vector
machines. Finally, eyes are precisely located by using binary vertical
projection and eye classifier in eye pair images. The proposed method
is robust to deal with illumination changes, moderate rotations, glasses
wearing and different eye states. Experimental results demonstrate its
effectiveness.
Abstract: For sterilization of Phalaenopsis culture medium without autoclaving, selected single sterilizing agents and in combinations were added to a 25ml Hyponex medium in a 120ml glass container. Treated liquid and solid media, supplemented with sterilizing agents, were compared to a control medium, autoclaved at 121°C for 15min. It was found that 90(L of 10% povidone-iodine, 150(L of 5.25% sodium hypochlorite, 150(L of 2% mercurochrome, 90(L of 2.5% iodine + 2.5% potassium iodine in combination with 10% providone-iodine (1:3) and 30(L of 2.5% iodine + 2.5% potassium iodide in combination with 2% mercurochrome showed 100% sterile conditions in liquid medium but provided 75, 100, 50, 75 and 80% sterile conditions, respectively, in solid medium. For growth of Phalaenopsis protocorms, 90(L of 10% povidone-iodine in liquid Hyponex medium gave the comparable growth of protocorms to control medium while 150(L of 5.25% sodium hypochlorite in solid medium provided the promising growth of protocorms. Growth of protocorms, whole fresh weight, numbers of leaf and root, root length and number of protocorm-like bodies, was discussed.
Abstract: In this investigation, anatase TiO2 thin films were
grown by radio frequency magnetron sputtering on glass substrates at
a high sputtering pressure and room temperature. The anatase films
were then annealed at 300-600 °C in air for a period of 1 hour. To
examine the structure and morphology of the films, X-ray diffraction
(XRD) and atomic force microscopy (AFM) methods were used
respectively. From X-ray diffraction patterns of the TiO2 films, it was
found that the as-deposited film showed some differences compared
with the annealed films and the intensities of the peaks of the
crystalline phase increased with the increase of annealing
temperature. From AFM images, the distinct variations in the
morphology of the thin films were also observed. The optical
constants were characterized using the transmission spectra of the
films obtained by UV-VIS-IR spectrophotometer. Besides, optical
thickness of the film deposited at room temperature was calculated
and cross-checked by taking a cross-sectional image through SEM.
The optical band gaps were evaluated through Tauc model. It was
observed that TiO2 films produced at room temperatures exhibited
high visible transmittance and transmittance decreased slightly with
the increase of annealing temperatures. The films were found to be
crystalline having anatase phase. The refractive index of the films
was found from 2.31-2.35 in the visible range. The extinction
coefficient was nearly zero in the visible range and was found to
increase with annealing temperature. The allowed indirect optical
band gap of the films was estimated to be in the range from 3.39 to
3.42 eV which showed a small variation. The allowed direct band
gap was found to increase from 3.67 to 3.72 eV. The porosity was
also found to decrease at a higher annealing temperature making the
film compact and dense.
Abstract: A structural study of an aqueous electrolyte whose
experimental results are available. It is a solution of LiCl-6H2O type
at glassy state (120K) contrasted with pure water at room temperature
by means of Partial Distribution Functions (PDF) issue from neutron
scattering technique. Based on these partial functions, the Reverse
Monte Carlo method (RMC) computes radial and angular correlation
functions which allow exploring a number of structural features of
the system. The obtained curves include some artifacts. To remedy
this, we propose to introduce a screened potential as an additional
constraint. Obtained results show a good matching between
experimental and computed functions and a significant improvement
in PDFs curves with potential constraint. It suggests an efficient fit of
pair distribution functions curves.
Abstract: In this study, an ablation, mechanical and thermal properties of a rocket motor insulation from phenolic/ fiber matrix composites forming a laminate with different fiber between fiberglass and locally available synthetic fibers. The phenolic/ fiber matrix composites was mechanics and thermal properties by means of tensile strength, ablation, TGA and DSC. The design of thermal insulation involves several factors.Determined the mechanical properties according to MIL-I-24768: Density >1.3 g/cm3, Tensile strength >103 MPa and Ablation
Abstract: Fabrication and efficiency enhancement of non-mercury, high efficiency and green field emission lamps using carbon nano-materials such as carbon nanotubes as cathode field emitters was studied. Phosphor was coated on the ITO glass or metal substrates as the anode. The luminescence efficiency enhancement was carried out by upgrading the uniform of the emitters, improving electron and thermal conductivity of the phosphor and the optimization of the design of different cathode/anode configurations. After evaluation of the aforementioned parameters, the luminescence efficiency of the field emission lamps was raised.
Abstract: In this study the effect of incorporation of recycled
glass-fibre reinforced polymer (GFRP) waste materials, obtained by
means of milling processes, on mechanical behaviour of polyester
polymer mortars was assessed. For this purpose, different contents of
recycled GFRP waste powder and fibres, with distinct size gradings,
were incorporated into polyester based mortars as sand aggregates
and filler replacements. Flexural and compressive loading capacities
were evaluated and found better than unmodified polymer mortars.
GFRP modified polyester based mortars also show a less brittle
behaviour, with retention of some loading capacity after peak load.
Obtained results highlight the high potential of recycled GFRP waste
materials as efficient and sustainable reinforcement and admixture for
polymer concrete and mortars composites, constituting an emergent
waste management solution.
Abstract: Mechanical design of the thin-film solar framed
module and mounting system is important to enhance module
reliability and to increase areas of applications. The stress induced by
different mounting positions played a main role controlling the
stability of the whole mechanical structure. From the finite element
method, under the pressure from the back of module, the stress at Lc
(center point of the Long frame) increased and the stresses at Center,
Corner and Sc (center point of the Short frame) decreased while the
mounting position was away from the center of the module. In addition,
not only the stress of the glass but also the stress of the frame
decreased. Accordingly it was safer to mount in the position away
from the center of the module. The emphasis of designing frame
system of the module was on the upper support of the Short frame.
Strength of the overall structure and design of the corner were also
important due to the complexity of the stress in the Long frame.
Abstract: Commercial hydroxyapatite (HA) was reinforced by
adding 2, 5, and 10 wt % of 28.5%CaO-28.5%P2O5-38%Na2 O-
5%CaF2 based glass and then sintered. Although HA shows good
biocompatibility with the human body, its applications are limited to
non load-bearing areas and coatings due to its poor mechanical
properties. These mechanical properties can be improved
substantially with addition of glass ceramics by sintering. In this
study, the effects of sintering hydroxyapatite with above specified
phosphate glass additions are quantified. Each composition was
sintered over a range of temperatures. Scanning electron microscopy
and x-ray diffraction were used to characterize the microstructure and
phases of the composites. The density, microhardness, and
compressive strength were measured using Archimedes Principle,
Vickers Microhardness Tester (at 0.98 N), and Instron Universal
Testing Machine (cross speed of 0.5 mm/min) respectively. These
results were used to indicate which composition provided suitable
material for use in hard tissue replacement. Composites containing 10
wt % glass additions formed dense HA/TCP (tricalcium phosphate)
composite materials possessing good compressive strength and
hardness than HA. In-vitro bioactivity was assessed by evaluating
changes in pH and Ca2+ ion concentration of SBF-simulated body
fluid on immersion of these composites in it for two weeks.
Abstract: In this study, hydroxyapatite (HA) composites are
prepared on addition of 30%CaO-30%P2O5-40%Na2 O based glass to
pure HA, in proportion of 2, 5, and 10 wt %. Each composition was
sintered over a range of temperatures. The quantitative phase
analysis was carried out using XRD and the microstructures were
studied using SEM. The density, microhardness, and compressive
strength have shown increase with the increasing amount of glass
addition. The resulting composites have chemical compositions that
are similar to the inorganic constituent of the mineral part of bone,
and constitutes trace elements like Na. X-ray diffraction showed no
decomposition of HA to secondary phases, however, the glass
reinforced-HA composites contained a HA phase and variable
amounts of tricalcium phosphate phase, depending on the amount of
bioglass added. The HA-composite material exhibited higher
compressive strength compared to sintered HA. The HA composite
reinforced with 10 wt % bioglass showed highest bioactivity level.
Abstract: Considering toxicity of heavy metals and their
accumulation in domestic wastes, immobilization of lead and
cadmium is envisaged inside glass-ceramics. We particularly
focused this work on calcium-rich phases embedded in a
glassy matrix.
Glass-ceramics were synthesized from glasses doped with
12 wt% and 16 wt% of PbO or CdO. They were observed and
analyzed by Electron MicroProbe Analysis (EMPA) and
Analytical Scanning Electron Microscopy (ASEM). Structural
characterization of the samples was performed by powder XRay
Diffraction.
Diopside crystals of CaMgSi2O6 composition are shown to
incorporate significant amounts of cadmium (up to 9 wt% of
CdO). Two new crystalline phases are observed with very
high Cd or Pb contents: about 40 wt% CdO for the cadmiumrich
phase and near 60 wt% PbO for the lead-rich phase. We
present complete chemical and structural characterization of
these phases. They represent a promising way for the
immobilization of toxic elements like Cd or Pb since glass
ceramics are known to propose a “double barrier" protection
(metal-rich crystals embedded in a glass matrix) against metal
release in the environment.
Abstract: Controlled release urea has become popular in agricultural industry as it helps to solve environmental issues and increase crop yield. Recently biomass was identified to replace the polymer used as a coating material in the conventional coated urea. In this paper spreading and contact angle of biomass droplet (lignin, cellulose and clay) on urea surface are investigated experimentally. There were two tests were conducted, sessile drop for contact angle measurement and pendant drop for contact angle measurement. A different concentration of biomass droplet was released from 30 mm above a substrate. Glass was used as a controlled substrate. Images were recorded as soon as the droplet impacted onto the urea before completely adsorb into the urea. Digitized droplets were then used to identify the droplet-s surface tension and contact angle. There is large difference observed between the low surface tension and high surface tension liquids, where the wetting and spreading diameter is higher for lower surface tension. From the contact angle results, the data showed that the biomass coating films were possible as wetting liquid (θ < 90º). Contact angle of biomass coating material gives good indication for the wettablity of a liquid on urea surface.