Abstract: Pressure vessels are usually operating at temperatures
where the conditions of linear elastic fracture mechanics are no
longer met because massive plasticity precedes crack propagation. In
this work the development of a surface crack in a pressure vessel
subject to bending and tension under elastic-plastic fracture
mechanics conditions was investigated. Finite element analysis was
used to evaluate the hydrostatic stress, the J-integral and crack
growth for semi-elliptical surface-breaking cracks. The results
showed non-uniform stress triaxiality and crack driving force around
the crack front at large deformation levels. Different ductile crack
extensions were observed which emphasis the dependent of ductile
tearing on crack geometry and type of loading. In bending the crack
grew only beneath the surface, and growth was suppressed at the
deepest segment. This contrasts to tension where the crack breaks
through the thickness with uniform growth along the entire crack
front except at the free surface. Current investigations showed that
the crack growth developed under linear elastic fracture mechanics
conditions will no longer be applicable under ductile tearing
scenarios.
Abstract: Dehydration of methanol to dimethyl ether (DME)
over a commercial Al2O3 catalyst was studied in an isothermal integral
fixed bed reactor. The experiments were performed on the temperature
interval 513-613 K, liquid hourly space velocity (LHSV) of 0.9-2.1h-1,
pressures between 0.1 and 1.0 MPa. The effect of different operation
conditions on the dehydration of methanol was investigated in a
laboratory scale experiment. A new intrinsic kinetics equation based
on the mechanism of Langmuir-Hinshelwood dissociation adsorption
was developed for the dehydration reaction by fitting the expressions
to the experimental data. An activation energy of 67.21 kJ/mol was
obtained for the catalyst with the best performance. Statistic test
showed that this new intrinsic kinetics equation was acceptable.
Abstract: Australia, while being a large and eager consumer of
innovative and cutting edge Information and Communication
Technologies (ICT), continues to struggle to remain a leader in
Technological Innovation. This paper has two main contributions to
address certain aspects of this complex issue. The first being the
current findings of an ongoing research project on Information and
Innovation Management in the Australian Information and
Communication Technologies (ICT) sector. The major issues being
considered by the project include: investigation of the possible
inherent entrepreneurial nature of ICT; how to foster ICT innovation;
and examination of the inherent difficulties currently found within
the ICT industry of Australia in regards to supporting the
development of innovative and creative ideas. The second major
contribution is details of the I.-C.A.N. (Innovation by Collaborative
Anonymous Networking) software application information
management tool created and evolving in our research group. I-CAN,
besides having a positive reinforcement acronym, is aimed at
facilitating productive collaborative innovation in an Australian
workplace. Such a work environment is frequently subjected to
cultural influences such as the 'tall poppy syndrome' and 'negative'
or 'unconstructive' peer-pressure. There influences are frequently
seen as inhibitors to employee participation, entrepreneurship and
innovation.
Abstract: In this paper, the deformation modes of a compact impact absorption member subjected to axial compression are investigated using finite element method and experiments. A multiple combination compact impact absorption member, referred to as a 'compress-expand member', is proposed to substitute the conventional thin-walled circular tube. This study found that the proposed compact impact absorption member has stable load increase characteristics and a wider range of high load efficiency (Pave/Pmax) than the thin-walled circular tube. Moreover, the proposed compact impact absorption member can absorb larger loads in a smaller radius than the thin-walled cylindrical tube, as it can maintain its stable deformation in increased wall thicknesses.
Abstract: Performance of a dual maximal ratio combining
receiver has been analyzed for M-ary coherent and non-coherent
modulations over correlated Nakagami-m fading channels with nonidentical
and arbitrary fading parameter. The classical probability
density function (PDF) based approach is used for analysis.
Expressions for outage probability and average symbol error
performance for M-ary coherent and non-coherent modulations have
been obtained. The obtained results are verified against the special
case published results and found to be matching. The effect of the
unequal fading parameters, branch correlation and unequal input
average SNR on the receiver performance has been studied.
Abstract: The expansion mechanism of a partially ionized plasma produced by laser interaction with solid target (copper) is studied. For this purpose we use a hydrodynamical model which includes a source term combined with Saha's equation. The obtained self-similar solution in the limit of quasi-neutrality shows that the expansion, at the earlier stage, is driven by the combination of thermal pressure and electrostatic potential. They are of the same magnitude. The initial ionized fraction and the temperature are the leading parameters of the expanding profiles,
Abstract: It is established that the instantaneous heart rate (HR) of healthy humans keeps on changing. Analysis of heart rate variability (HRV) has become a popular non invasive tool for assessing the activities of autonomic nervous system. Depressed HRV has been found in several disorders, like diabetes mellitus (DM) and coronary artery disease, characterised by autonomic nervous dysfunction. A new technique, which searches for pattern repeatability in a time series, is proposed specifically for the analysis of heart rate data. These set of indices, which are termed as pattern repeatability measure and pattern repeatability ratio are compared with approximate entropy and sample entropy. In our analysis, based on the method developed, it is observed that heart rate variability is significantly different for DM patients, particularly for patients with diabetic foot ulcer.
Abstract: Most of ignition delay correlations studies have been
developed in a constant volume bombs which cannot capture the
dynamic variation in pressure and temperature during the ignition
delay as in real engines. Watson, Assanis et. al. and Hardenberg
and Hase correlations have been developed based on experimental
data of diesel engines. However, they showed limited predictive
ability of ignition delay when compared to experimental results. The
objective of the study was to investigate the dependency of ignition
delay time on engine brake power. An experimental investigation of
the effect of automotive diesel and water diesel emulsion fuels on
ignition delay under steady state conditions of a direct injection diesel
engine was conducted. A four cylinder, direct injection naturally
aspirated diesel engine was used in this experiment over a wide range
of engine speeds and two engine loads. The ignition delay
experimental data were compared with predictions of Assanis et. al.
and Watson ignition delay correlations. The results of the
experimental investigation were then used to develop a new ignition
delay correlation. The newly developed ignition delay correlation has
shown a better agreement with the experimental data than Assanis et.
al. and Watson when using automotive diesel and water diesel
emulsion fuels especially at low to medium engine speeds at both
loads. In addition, the second derivative of cylinder pressure which is
the most widely used method in determining the start of combustion
was investigated.
Abstract: This paper presents the use of a semi-classical signal
analysis method that has been developed recently for the analysis of
turbomachinery flow unsteadiness. We will focus on the correlation
between theSemi-Classical Signal Analysis parameters and some
physical parameters in relation with turbomachinery features. To
demonstrate the potential of the proposed approach, a static pressure
signal issued from a rotor/stator interaction of a centrifugal pump is
studied. Several configurations of the pump are compared.
Abstract: The purpose of the study was to determine the amount of Palm Kernel Oil (PKO) extracted from a packed bed of palm kernels in a supercritical fluid extractor using supercritical carbon dioxide (SC-CO2) as an environmental friendly solvent. Further, the study sought to ascertain the values of the overall mass transfer coefficient (K) of PKO evaluation through a mass transfer model, at constant temperature of 50 °C, 60 °C, and 70 °C and pressures range from 27.6 MPa, 34.5 MPa, 41.4 MPa and 48.3 MPa respectively. Finally, the study also seeks to demonstrate the application of the overall mass transfer coefficient values in relation to temperature and pressure. The overall mass transfer coefficient was found to be dependent pressure at each constant temperature of 50 °C, 60 °C and 70 °C. The overall mass transfer coefficient for PKO in a packed bed of palm kernels was found to be in the range of 1.21X 10-4 m min-1 to 1.72 X 10-4 m min-1 for a constant temperature of 50 °C and in the range of 2.02 X 10-4 m min-1 to 2.43 X 10-4 m min-1 for a constant temperature of 60 °C. Similar increasing trend of the overall mass transfer coefficient from 1.77 X 10-4 m min-1 to 3.64 X 10-4 m min-1 was also observed at constant temperature of 70 °C within the same pressure range from 27.6 MPa to 48.3 MPa.
Abstract: In this study two series of self compacting concrete
mixtures were prepared with 100% coarse recycled concrete
aggregates and different percentages of 0%, 20%, 40%, 60%, 80%
and 100% fine recycled concrete aggregates. In series I and II the
water to binder ratios were 0.50 and 0.45, respectively. The cement
content was kept 350
3 m
kg for those mixtures that don't have any
Nano-Silica. To improve the compressive strength of samples, Nano-
Silica replaced with 10% of cement weight in concrete mixtures. By
doing the tests, the results showed that, adding Nano-silica to the
samples with less percentage of fine recycled concrete aggregates,
lead to more increase on the compressive strength.
Abstract: This paper examines the forced convection flow of
incompressible, electrically conducting viscous fluid past a sharp
wedge in the presence of heat generation or absorption with an
applied magnetic field. The system of partial differential equations
governing Falkner - Skan wedge flow and heat transfer is first
transformed into a system of ordinary differential equations using
similarity transformations which is later solved using an implicit
finite - difference scheme, along with quasilinearization technique.
Numerical computations are performed for air (Pr = 0.7) and
displayed graphically to illustrate the influence of pertinent physical
parameters on local skin friction and heat transfer coefficients and,
also on, velocity and temperature fields. It is observed that the
magnetic field increases both the coefficients of skin friction and heat
transfer. The effect of heat generation or absorption is found to be
very significant on heat transfer, but its effect on the skin friction is
negligible. Indeed, the occurrence of overshoot is noticed in the
temperature profiles during heat generation process, causing the
reversal in the direction of heat transfer.
Abstract: We study bifurcation structure of the zonal jet flow the
streamfunction of which is expressed by a single spherical harmonics
on a rotating sphere. In the non-rotating case, we find that a steady
traveling wave solution arises from the zonal jet flow through Hopf
bifurcation. As the Reynolds number increases, several traveling
solutions arise only through the pitchfork bifurcations and at high
Reynolds number the bifurcating solutions become Hopf unstable. In
the rotating case, on the other hand, under the stabilizing effect of
rotation, as the absolute value of rotation rate increases, the number
of the bifurcating solutions arising from the zonal jet flow decreases
monotonically. We also carry out time integration to study unsteady
solutions at high Reynolds number and find that in the non-rotating
case the unsteady solutions are chaotic, while not in the rotating cases
calculated. This result reflects the general tendency that the rotation
stabilizes nonlinear solutions of Navier-Stokes equations.
Abstract: Recently, the health of retired National Football
League players, particularly lineman has been investigated. A
number of studies have reported increased cardiometabolic risk,
premature cardiovascular disease and incidence of type 2 diabetes.
Rugby union players have somatotypes very similar to National
Football League players which suggests that rugby players may have
similar health risks. The International Golden Oldies World Rugby
Festival (GORF) provided a unique opportunity to investigate the
demographics of veteran rugby players. METHODOLOGIES: A
cross-sectional, observational study was completed using an online
web-based questionnaire that consisted of medical history and
physiological measures. Data analysis was completed using a one
sample t-test (50yrs) and Chi-square test. RESULTS:
A total of 216 veteran rugby competitors (response rate = 6.8%)
representing 10 countries, aged 35-72 yrs (mean 51.2, S.D. ±8.0),
participated in the online survey. As a group, the incidence of current
smokers was low at 8.8% (avg 72.4 cigs/wk) whilst the percentage
consuming alcohol was high (93.1% (avg 11.2 drinks/wk).
Competitors reported the following top six chronic
diseases/disorders; hypertension (18.6%), arthritis (OA/RA, 11.5%),
asthma (9.3%), hyperlipidemia (8.2%), diabetes (all types, 7.5%) and
gout (6%), there were significant differences between groups with
regard to cancer (all types) and migraines. When compared to the
Australian general population (Australian Bureau of Statistics data,
n=18,000), GORF competitors had a significantly lower incidence of
anxiety (p
Abstract: Limited infrastructure development on peats and
organic soils is a serious geotechnical issues common to many
countries of the world especially Malaysia which distributed 1.5 mill
ha of those problematic soil. These soils have high water content and
organic content which exhibit different mechanical properties and
may also change chemically and biologically with time. Constructing
structures on peaty ground involves the risk of ground failure and
extreme settlement. Nowdays, much efforts need to be done in
making peatlands usable for construction due to increased landuse.
Deep mixing method employing cement as binders, is generally used
as measure again peaty/ organic ground failure problem. Where the
technique is widely adopted because it can improved ground
considerably in a short period of time. An understanding of
geotechnical properties as shear strength, stiffness and compressibility
behavior of these soils was requires before continues construction on
it. Therefore, 1- 1.5 meter peat soil sample from states of Johor and
an organic soil from Melaka, Malaysia were investigated. Cement
were added to the soil in the pre-mixing stage with water cement ratio
at range 3.5,7,14,140 for peats and 5,10,30 for organic soils,
essentially to modify the original soil textures and properties. The
mixtures which in slurry form will pour to polyvinyl chloride (pvc)
tube and cured at room temperature 250C for 7,14 and 28 days.
Laboratory experiments were conducted including unconfined
compressive strength and bender element , to monitor the improved
strength and stiffness of the 'stabilised mixed soils'. In between,
scanning electron miscroscopic (SEM) were observations to
investigate changes in microstructures of stabilised soils and to
evaluated hardening effect of a peat and organic soils stabilised
cement. This preliminary effort indicated that pre-mixing peat and
organic soils contributes in gaining soil strength while help the
engineers to establish a new method for those problematic ground
improvement in further practical and long term applications.
Abstract: The IFS is a scheme for describing and manipulating complex fractal attractors using simple mathematical models. More precisely, the most popular “fractal –based" algorithms for both representation and compression of computer images have involved some implementation of the method of Iterated Function Systems (IFS) on complete metric spaces. In this paper a new generalized space called Multi-Fuzzy Fractal Space was constructed. On these spases a distance function is defined, and its completeness is proved. The completeness property of this space ensures the existence of a fixed-point theorem for the family of continuous mappings. This theorem is the fundamental result on which the IFS methods are based and the fractals are built. The defined mappings are proved to satisfy some generalizations of the contraction condition.
Abstract: A new analysis of perceptual speech enhancement is
presented. It focuses on the fact that if only noise above the masking
threshold is filtered, then noise below the masking threshold, but
above the absolute threshold of hearing, can become audible after the
masker filtering. This particular drawback of some perceptual filters,
hereafter called the maskee-to-audible-noise (MAN) phenomenon,
favours the emergence of isolated tonals that increase musical noise.
Two filtering techniques that avoid or correct the MAN phenomenon
are proposed to effectively suppress background noise without introducing
much distortion. Experimental results, including objective
and subjective measurements, show that these techniques improve
the enhanced speech quality and the gain they bring emphasizes the
importance of the MAN phenomenon.
Abstract: There are reports of gas and oil wells fire due to different accidents. Many different methods are used for fire fighting in gas and oil industry. Traditional fire extinguishing techniques are mostly faced with many problems and are usually time consuming and needs lots of equipments. Besides, they cause damages to facilities, and create health and environmental problems. This article proposes innovative approach in fire extinguishing techniques in oil and gas industry, especially applicable for burning oil wells located offshore. Fire extinguishment employing a turbojet is a novel approach which can help to extinguishment the fire in short period of time. Divergent and convergent turbojets modeled in laboratory scale along with a high pressure flame were used. Different experiments were conducted to determine the relationship between output discharges of trumpet and oil wells. The results were corrected and the relationship between dimensionless parameters of flame and fire extinguishment distances and also the output discharge of turbojet and oil wells in specified distances are demonstrated by specific curves.
Abstract: This paper proposes a method that discovers sequential patterns corresponding to user-s interests from sequential data. This method expresses the interests as constraint patterns. The constraint patterns can define relationships among attributes of the items composing the data. The method recursively decomposes the constraint patterns into constraint subpatterns. The method evaluates the constraint subpatterns in order to efficiently discover sequential patterns satisfying the constraint patterns. Also, this paper applies the method to the sequential data composed of stock price indexes and verifies its effectiveness through comparing it with a method without using the constraint patterns.
Abstract: The aim of this study is to discuss the relationship between tourist awareness of environmental issues and their own recreational behaviors in the Taipei Guandu Wetland. A total of 392 questionnaires were gathered for data analysis using descriptive statistics, t-testing, one-way analysis of variance (ANOVA) and least significant difference (LSD) post hoc comparisons. The results showed that most of the visitors there enjoying the beautiful scenery are 21 to 30 years old with a college education. The means and standard deviations indicate that tourists express a positive degree of cognition of environmental issues and recreational behaviors. They suggest that polluting the environment is harmful to the natural ecosystem and that the natural resources of ecotourism are fragile, as well as expressing a high degree of recognition of the need to protect wetlands. Most of respondents are cognizant of the regulations proposed by the Guandu Wetland administration which asks that users exercise self-control and follow recommended guidelines when traveling the wetland. There were significant differences in the degree of cognition related to the variables of age, number of visits and reasons for visiting. We found that most respondents with relatively high levels of education would like to learn more about the wetland and are supportive of its conservation.