Abstract: Hydrothermal liquefaction (HTL) is a technique for obtaining clean biofuel from biomass in the presence of heat and pressure in an aqueous medium which leads to a decomposition of this biomass to the formation of various products. A role of operating conditions is essential for the bio-oil and other products’ yield and also quality of the products. The effects of these parameters were investigated in regards to the composition and yield of the products. Chlorellaceae microalgae were tested under different HTL conditions to clarify suitable conditions for extracting bio-oil together with value-added co-products. Firstly, different microalgae loading rates (5-30%) were tested and found that this parameter has not much significant to product yield. Therefore, 10% microalgae loading rate was selected as a proper economical solution for conditioned schedule at 250oC and 30 min-reaction time. Next, a range of temperature (210-290oC) was applied to verify the effects of each parameter by keeping the reaction time constant at 30 min. The results showed no linkage with the increase of the reaction temperature and some reactions occurred that lead to different product yields. Moreover, some nutrients found in the aqueous product are possible to be utilized for nutrient recovery.
Abstract: Rice straw is lignocellulosic biomass which can be utilized as substrate for the biogas production. However, due to the property and composition of rice straw, it is difficult to be degraded by hydrolysis enzymes. One of the pretreatment methods that modify such properties of lignocellulosic biomass is the application of lignocellulose-degrading microbial consortia. The aim of this study is to investigate the effect of microbial consortia to enhance biogas production. To select the high efficient consortium, cellulase enzymes were extracted and their activities were analyzed. The results suggested that microbial consortium culture obtained from cattle manure is the best candidate compared to decomposed wood and horse manure. A microbial consortium isolated from cattle manure was then mixed with anaerobic sludge and used as inoculum for biogas production. The optimal conditions for biogas production were investigated using response surface methodology (RSM). The tested parameters were the ratio of amount of microbial consortium isolated and amount of anaerobic sludge (MI:AS), substrate to inoculum ratio (S:I) and temperature. Here, the value of the regression coefficient R2 = 0.7661 could be explained by the model which is high to advocate the significance of the model. The highest cumulative biogas yield was 104.6 ml/g-rice straw at optimum ratio of MI:AS, ratio of S:I, and temperature of 2.5:1, 15:1 and 44°C respectively.
Abstract: The present work attempts to investigate the
combustion, performance and emission characteristics of an existing
single-cylinder four-stroke compression-ignition engine operated in
dual-fuel mode with hydrogen as an alternative fuel. Environmental
concerns and limited amount of petroleum fuels have caused interests
in the development of alternative fuels like hydrogen for internal
combustion (IC) engines. In this experimental investigation, a diesel
engine is made to run using hydrogen in dual fuel mode with diesel,
where hydrogen is introduced into the intake manifold using an LPGCNG
injector and pilot diesel is injected using diesel injectors. A
Timed Manifold Injection (TMI) system has been developed to vary
the injection strategies. The optimized timing for the injection of
hydrogen was 10^0 CA after top dead center (ATDC). From the study
it was observed that with increasing hydrogen rate, enhancement in
brake thermal efficiency (BTHE) of the engine has been observed
with reduction in brake specific energy consumption (BSEC).
Furthermore, Soot contents decrease with an increase in indicated
specific NOx emissions with the enhancement of hydrogen flow rate.
Abstract: We address a new integer frequency offset (IFO)
estimation scheme with an aid of a pilot for orthogonal frequency
division multiplexing systems. After correlating each continual pilot
with a predetermined scattered pilot, the correlation value is again
correlated to alleviate the influence of the timing offset. From
numerical results, it is demonstrated that the influence of the timing
offset on the IFO estimation is significantly decreased.
Abstract: This paper presents effects of the mean operating
pressure on the optimal operating frequency based on temperature
differences across stack ends in a thermoacoustic refrigerator. In
addition to the length of the resonance tube, components of the
thermoacoustic refrigerator have an influence on the operating
frequency due to their acoustic properties, i.e., absorptivity,
reflectivity and transmissivity. The interference of waves incurs and
distorts the original frequency generated by the driver so that the
optimal operating frequency differs from the designs. These acoustic
properties are not parameters in the designs and be very complicated
to infer their responses. A prototype thermoacoustic refrigerator is
constructed and used to investigate its optimal operating frequency
compared to the design at various operating pressures. Helium and air
are used as working fluids during the experiments. The results
indicate that the optimal operating frequency of the prototype
thermoacoustic refrigerator using helium is at 6 bar and 490Hz or
approximately 20% away from the design frequency. The optimal
operating frequency at other mean pressures differs from the design
in an unpredictable manner, however, the optimal operating
frequency and pressure can be identified by testing.
Abstract: The paper is focused on the identification of limiting
environmental factors of individual industrial floors on which newly
developed polymer protection and repair systems with the use of
secondary raw materials will be used. These mainly include floors
with extreme stresses and special requirements for materials used. In
relation to the environment of a particular industrial floor, it is
necessary to ensure, for example, chemical stability, resistance to
higher temperatures, resistance to higher mechanical stress, etc. for
developed materials, which is reflected in the demands for the
developed material systems. The paper describes individual
environments and, in relation to them, also requirements for
individual components of the developed materials and for the
developed materials as a whole.
Abstract: An innovative flooring underlayment was produced
and tested. The composite system is made of common OSB boards
and a layer of eco-friendly non-cement gypsum based material
(GeoGypTM). It was found that the shear bond between the two
materials is sufficient to secure the composite interaction between the
two. The very high compressive strength and relatively high tensile
strength of the non-cement based component together with its high
modulus of elasticity provides enough strength and stiffness for the
composite product to cover wider spacing between the joists. The
initial findings of this study indicate that with joist spacing as wide as
800 mm, the flooring system provides enough strength without
compromising the serviceability requirements of the building codes.
Abstract: Scrubbing by a liquid spraying is one of the most
effective processes used for removal of fine particles and soluble
gas pollutants (such as SO2, HCl, HF) from the flue gas. There are
many configurations of scrubbers designed to provide contact
between the liquid and gas stream for effectively capturing
particles or soluble gas pollutants, such as spray plates, packed bed
towers, jet scrubbers, cyclones, vortex and venturi scrubbers. The
primary function of venturi scrubber is the capture of fine particles
as well as HCl, HF or SO2 removal with effect of the flue gas
temperature decrease before input to the absorption column. In this
paper, sulfur dioxide (SO2) from flue gas was captured using new
design replacing venturi scrubber (1st degree of wet scrubbing).
The flue gas was prepared by the combustion of the carbon
disulfide solution in toluene (1:1 vol.) in the flame in the reactor.
Such prepared flue gas with temperature around 150°C was
processed in designed laboratory O-element scrubber. Water was
used as absorbent liquid. The efficiency of SO2 removal, pressure
drop and temperature drop were measured on our experimental
device. The dependence of these variables on liquid-gas ratio was
observed. The average temperature drop was in the range from
150°C to 40°C. The pressure drop was increased with increasing of
a liquid-gas ratio, but no too much as for the common venturi
scrubber designs. The efficiency of SO2 removal was up to 70 %.
The pressure drop of our new designed wet scrubber is similar to
commonly used venturi scrubbers; nevertheless the influence of
amount of the liquid on pressure drop is not so significant.
Abstract: Reliability of long-term storage products is related to
the availability of the whole system, and the evaluation of storage life
is of great necessity. These products are usually highly reliable and
little failure information can be collected. In this paper, an analytical
method based on data from accelerated storage life test is proposed to
evaluate the reliability index of the long-term storage products. Firstly,
singularities are eliminated by data normalization and residual
analysis. Secondly, with the preprocessed data, the degradation path
model is built to obtain the pseudo life values. Then by life distribution
hypothesis, we can get the estimator of parameters in high stress levels
and verify failure mechanism consistency. Finally, the life distribution
under the normal stress level is extrapolated via the acceleration model
and evaluation of the actual average life is available. An application
example with the camera stabilization device is provided to illustrate
the methodology we proposed.
Abstract: Propylene self-metathesis to ethylene and butene was
studied over WOx/SiO2 catalysts at 450oC and atmospheric pressure.
The WOx/SiO2 catalysts were prepared by incipient wetness
impregnation of ammonium metatungstate aqueous solution. It was
found that, adding nano-sized extra supports (SiO2 and TiO2) by
physical mixing with the WOx/SiO2 enhanced propylene conversion.
The UV-Vis and FT-Raman results revealed that WOx could migrate
from the original silica support to the extra support, leading to a
better dispersion of WOx. The ICP-OES results also indicate that
WOx existed on the extra support. Coke formation was investigated
on the catalysts after 10 h time-on-stream by TPO. However, adding
nano-sized extra supports led to higher coke formation which may be
related to acidity as characterized by NH3-TPD.
Abstract: This paper presents the design and fabrication of an
optical window for an optical modulator toward image sensing
applications. An optical window consists of micrometer-order SiO2
capillaries (porous solid) that can modulate transmission light
intensity by moving the liquid in and out of porous solid. A high
optical transmittance of the optical window can be achieved due to
refractive index matching when the liquid is penetrated into the
porous solid. Otherwise, its light transmittance is lower because of
light reflection and scattering by air holes and capillary walls. Silicon
capillaries fabricated by deep reactive ion etching (DRIE) process are
completely oxidized to form the SiO2 capillaries. Therefore, high
aspect ratio SiO2 capillaries can be achieved based on silicon
capillaries formed by DRIE technique. Large compressive stress of
the oxide causes bending of the capillary structure, which is reduced
by optimizing the design of device structure. The large stress of the
optical window can be released via thin supporting beams. A 7.2 mm
x 9.6 mm optical window area toward a fully integrated with the
image sensor format is successfully fabricated and its optical
transmittance is evaluated with and without inserting liquids (ethanol
and matching oil). The achieved modulation range is approximately
20% to 35% with and without liquid penetration in visible region
(wavelength range from 450 nm to 650 nm).
Abstract: This study investigates the suitability of using plastic,
such as polyethylene terephthalate (PET), as a partial replacement of
natural coarse and fine aggregates (for example, brick chips and
natural sand) to produce lightweight concrete for load bearing
structural members. The plastic coarse aggregate (PCA) and plastic
fine aggregate (PFA) were produced from melted polyethylene
terephthalate (PET) bottles. Tests were conducted using three
different water–cement (w/c) ratios, such as 0.42, 0.48, and 0.57,
where PCA and PFA were used as 50% replacement of coarse and
fine aggregate respectively. Fresh and hardened properties of
concrete have been compared for natural aggregate concrete (NAC),
PCA concrete (PCC) and PFA concrete (PFC). The compressive
strength of concrete at 28 days varied with the water–cement ratio for
both the PCC and PFC. Between PCC and PFC, PFA concrete
showed the highest compressive strength (23.7 MPa) at 0.42 w/c ratio
and also the lowest compressive strength (13.7 MPa) at 0.57 w/c
ratio. Significant reduction in concrete density was mostly observed
for PCC samples, ranging between 1977–1924 kg/m³. With the
increase in water–cement ratio PCC achieved higher workability
compare to both NAC and PFC. It was found that both the PCA and
PFA contained concrete achieved the required compressive strength
to be used for structural purpose as partial replacement of the natural
aggregate; but to obtain the desired lower density as lightweight
concrete the PCA is most suited.
Abstract: All the software engineering researches and best
industry practices aim at providing software products with high
degree of quality and functionality at low cost and less time. These
requirements are addressed by the Component Based Software
Engineering (CBSE) as well. CBSE, which deals with the software
construction by components’ assembly, is a revolutionary extension
of Software Engineering. CBSE must define and describe processes
to assure timely completion of high quality software systems that are
composed of a variety of pre built software components. Though
these features provide distinct and visible benefits in software design
and programming, they also raise some challenging problems. The
aim of this work is to summarize the pertinent issues and
considerations in CBSE to make an understanding in forms of
concepts and observations that may lead to development of newer
ways of dealing with the problems and challenges in CBSE.
Abstract: Exact solution of an unsteady MHD flow of elasticoviscous
fluid through a porous media in a tube of spherical cross
section under the influence of magnetic field and constant pressure
gradient has been obtained in this paper. Initially, the flow is
generated by a constant pressure gradient. After attaining the steady
state, the pressure gradient is suddenly withdrawn and the resulting
fluid motion in a tube of spherical cross section by taking into
account of the porosity factor and magnetic parameter of the
bounding surface is investigated. The problem is solved in two-stages
the first stage is a steady motion in tube under the influence of a
constant pressure gradient, the second stage concern with an unsteady
motion. The problem is solved employing separation of variables
technique. The results are expressed in terms of a non-dimensional
porosity parameter (K), magnetic parameter (m) and elasticoviscosity
parameter (β), which depends on the Non-Newtonian
coefficient. The flow parameters are found to be identical with that of
Newtonian case as elastic-viscosity parameter and magnetic
parameter tends to zero and porosity tends to infinity. It is seen that
the effect of elastico-viscosity parameter, porosity parameter and
magnetic parameter of the bounding surface has significant effect on
the velocity parameter.
Abstract: Taiwan is a hyper endemic area for the Hepatitis B
virus (HBV). The estimated total number of HBsAg carriers in the
general population who are more than 20 years old is more than 3
million. Therefore, a case record review is conducted from January
2003 to June 2007 for all patients with a diagnosis of acute hepatitis
who were admitted to the Emergency Department (ED) of a
well-known teaching hospital. The cost for the use of medical
resources is defined as the total medical fee. In this study, principal
component analysis (PCA) is firstly employed to reduce the number of
dimensions. Support vector regression (SVR) and artificial neural
network (ANN) are then used to develop the forecasting model. A total
of 117 patients meet the inclusion criteria. 61% patients involved in
this study are hepatitis B related. The computational result shows that
the proposed PCA-SVR model has superior performance than other
compared algorithms. In conclusion, the Child-Pugh score and
echogram can both be used to predict the cost of medical resources for
patients with acute hepatitis in the ED.
Abstract: In this paper, the effects of fiber types and elevated
temperatures on compressive strength, modulus of rapture and the
bond characteristics of fiber reinforced concretes (FRC) are
presented. By using the three different types of fibers (steel fiber-SF,
polypropylene-PPF and polyvinyl alcohol-PVA), FRC specimens
were produced and exposed to elevated temperatures up to 800 ºC for
1.5 hours. In addition, a plain concrete (without fiber) was produced
and used as a control. Test results obtained showed that the steel fiber
reinforced concrete (SFRC) had the highest compressive strength,
modulus of rapture and bond stress values at room temperatures, the
residual bond, flexural and compressive strengths of both FRC and
plain concrete dropped sharply after exposure to high temperatures.
The results also indicated that the reduction of bond, flexural and
compressive strengths with increasing the exposed temperature was
relatively less for SFRC than for plain, and FRC with PPF and PVA.
Abstract: This paper presents experimental investigation and
finite element analysis on buckling behavior of irregular section coldformed
steel columns under axially concentric loading. For the
experimental study, four different sections of columns were tested to
investigate effect of stiffening and width-to-thickness ratio on
buckling behavior. For each of the section, three lengths of 230, 950
and 1900 mm. were studied representing short, intermediate long and
long columns, respectively. Then, nonlinear finite element analyses
of the tested columns were performed. The comparisons in terms of
load-deformation response and buckling mode show good agreement
and hence the FEM models were validated. Parametric study of
stiffening element and thickness of 1.0, 1.15, 1.2, 1.5, 1.6 and 2.0
mm. was analyzed. The test results showed that stiffening effect pays
a large contribution to prevent distortional mode. The increase in wall
thickness enhanced buckling stress beyond the yielding strength in
short and intermediate columns, but not for the long columns.
Abstract: Verification of vented wooden façade system with
bonded joints is presented in this paper. The potential of bonded
joints is studied and described in more detail. The paper presents the results of an experimental and theoretical research about the effects of freeze cycling on the bonded joint. For the purpose of tests spruce
timber profiles were chosen for the load bearing substructure. Planks from wooden plastic composite and Siberian larch are representing facade cladding. Two types of industrial polyurethane adhesives intended for structural bonding were selected. The article is focused on the preparation as well as on the subsequent curing and conditioning of test samples. All test samples were subjected to 15 cycles that represents sudden temperature changes, i.e. immersion in a water bath at (293.15 ± 3) K for 6 hours and subsequent freezing to (253.15 ± 2) K for 18 hours. Furthermore, the retention of bond strength between substructure and cladding wastested and strength in shear was determined under tensile stress.Research data indicate that little, if any, damage to the bond results from freezingcycles. Additionally, the suitability of selected group of adhesives in combination with timber substructure was confirmed.
Abstract: Dental porcelain composites reinforced and toughened
by 20 wt.% tetragonal zirconia (3Y-TZP) were processed by hot
pressing at 1000°C. Two types of particles were tested: yttriastabilized
zirconia (ZrO2–3%Y2O3) agglomerates and pre-sintered
yttria-stabilized zirconia (ZrO2–3%Y2O3) particles. The composites
as well as the reinforcing particles were analyzed by the means of
optical and Scanning Electron Microscopy (SEM), Energy Dispersion
Spectroscopy (EDS) and X-Ray Diffraction (XRD). The mechanical
properties were obtained by the transverse rupture strength test. Wear
tests were also performed on the composites and monolithic
porcelain. The best mechanical results were displayed by the
porcelain reinforced with the pre-sintered ZrO2–3%Y2O3
agglomerates.
Abstract: In this paper, a numerical simulation of a finned store
separating from a wing-pylon configuration has been studied and
validated. A dynamic unstructured tetrahedral mesh approach is
accomplished by using three grid sizes to numerically solving the
discretized three dimensional, inviscid and compressible Euler
equations. The method used for computations of separation of an
external store assuming quasi-steady flow condition. Computations of
quasi-steady flow have been directly coupled to a six degree-offreedom
(6DOF) rigid-body motion code to generate store
trajectories. The pressure coefficients at four different angular cuts
and time histories of various trajectory parameters and wing pressure
distribution during the store separation are compared for every grid
size with published experimental data.