Abstract: This paper presents a new sufficient condition for the
existence, uniqueness and global asymptotic stability of the equilibrium point for Cohen-Grossberg neural networks with multiple time delays. The results establish a relationship between the network parameters
of the neural system independently of the delay parameters. The results are also compared with the previously reported results in
the literature.
Abstract: Mycophenolic acid “MPA" is a secondary metabolite
of Penicillium bervicompactum with antibiotic and
immunosuppressive properties. In this study, fermentation process
was established for production of mycophenolic acid by Penicillium
bervicompactum MUCL 19011 in shake flask. The maximum MPA
production, product yield and productivity were 1.379 g/L, 18.6 mg/g
glucose and 4.9 mg/L.h respectively. Glucose consumption, biomass
and MPA production profiles were investigated during fermentation
time. It was found that MPA production starts approximately after
180 hours and reaches to a maximum at 280 h. In the next step, the
effects of methionine and acetate concentrations on MPA production
were evaluated. Maximum MPA production, product yield and
productivity (1.763 g/L, 23.8 mg/g glucose and 6.30 mg/L. h
respectively) were obtained with using 2.5 g/L methionine in culture
medium. Further addition of methionine had not more positive effect
on MPA production. Finally, results showed that the addition of
acetate to the culture medium had not any observable effect on MPA
production.
Abstract: Stability of functionally graded beams with piezoelectric layers subjected to axial compressive load that is simply supported at both ends is studied in this paper. The displacement field of beam is assumed based on first order shear deformation beam theory. Applying the Hamilton's principle, the governing equation is established. The influences of applied voltage, dimensionless geometrical parameter, functionally graded index and piezoelectric thickness on the critical buckling load of beam are presented. To investigate the accuracy of the present analysis, a compression study is carried out with a known data.
Abstract: Carbon fibers are fabricated from different materials,
such as special polyacrylonitrile (PAN) fibers, rayon fibers and pitch.
Among these three groups of materials, PAN fibers are the most
widely used precursor for the manufacture of carbon fibers. The
process of fabrication carbon fibers from special PAN fibers includes
two steps; oxidative stabilization at low temperature and
carbonization at high temperatures in an inert atmosphere. Due to the
high price of raw materials (special PAN fibers), carbon fibers are
still expensive.
In the present work the main goal is making carbon fibers from
low price commercial PAN fibers with modified chemical
compositions. The results show that in case of conducting completes
stabilization process, it is possible to produce carbon fibers with
desirable tensile strength from this type of PAN fibers. To this
matter, thermal characteristics of commercial PAN fibers were
investigated and based upon the obtained results, with some changes
in conventional procedure of stabilization in terms of temperature
and time variables; the desirable conditions of complete stabilization
is achieved.
Abstract: This paper is concerned with the study of mineralogy
and engineering characteristics of soil materials derived from the
eastern part of Nile Delta. The clay minerals of the studied soil by
using X- ray diffraction are mainly illite (average 72.6 %) and
kaolinite (average 2.6 %), expandable portion in illite-smectite mixed
layer (average 7 %). Smectite is more abundant in fluviatile clays,
whereas kaolinite is more abundant in lagoonal clays. On the other
hand, illite and illite-smectite are more abundant in marine clays. The
geotechnical results show that the soil under study consists mainly of
about 0.3 % gravel, 5 % sand, 51.5 % silt and 42.2 % clay in average.
The average shrinkage limit attains 11 % whereas the average value
of the plasticity index is 23.4 %. The free swelling ranges from 40 %
to 75 % and has a value of 55 % giving an indication about the
inadequacy of such soil under foundations.
From a construction point of view, the soil under investigation
poses many problems even under light foundations due to the
swelling and shrinkage. Such swelling and shrinkage is due to the
high content of soil materials in the expandable clay minerals of illite
and smectite. Based on the results of the present and earlier studies,
trial application of soil stabilisation is recommended.
Abstract: The mountain road slope failures triggered by
earthquake activities and torrential rain namely to create the disaster.
Province Road No. 24 is a main route to the Wutai Township. The area
of the study is located at the mileages between 46K and 47K along the
road. However, the road has been suffered frequent damages as a result
of landslide and slope failures during typhoon seasons. An
understanding of the sliding behaviors in the area appears to be
necessary. Slope failures triggered by earthquake activities and heavy
rainfalls occur frequently. The study is to understand the mechanism
of slope failures and to look for the way to deal with the situation. In
order to achieve these objectives, this paper is based on theoretical and
structural geology data interpretation program to assess the potential
slope sliding behavior. The study showed an intimate relationship
between the landslide behavior of the slopes and the stratum materials,
based on structural geology analysis method to analysis slope stability
and finds the slope safety coefficient to predict the sites of destroyed
layer. According to the case study and parameter analyses results, the
slope mainly slips direction compared to the site located in the
southeast area. Find rainfall to result in the rise of groundwater level is
main reason of the landslide mechanism. Future need to set up
effective horizontal drain at corrective location, that can effective
restrain mountain road slope failures and increase stability of slope.
Abstract: This paper present a new method for design of power
system stabilizer (PSS) based on sliding mode control (SMC)
technique. The control objective is to enhance stability and improve
the dynamic response of the multi-machine power system. In order to
test effectiveness of the proposed scheme, simulation will be carried
out to analyze the small signal stability characteristics of the system
about the steady state operating condition following the change in
reference mechanical torque and also parameters uncertainties. For
comparison, simulation of a conventional control PSS (lead-lag
compensation type) will be carried out. The main approach is
focusing on the control performance which later proven to have the
degree of shorter reaching time and lower spike.
Abstract: The evolution in project management was triggered by
the changes in management philosophy and practices in order to
maintain competitive advantage and continuous success in the field.
The purpose of this paper is to highlight the practicality of cognitive
style and unlearning approach in influencing the achievement of
project success by project managers. It introduces the concept of
planning, knowing and creating style from cognitive style field in the
light of achieving time, cost, quality and stakeholders appreciation in
project success context. Further it takes up a discussion of the
unlearning approach as a moderator in enhancing the relationship
between cognitive style and project success. The paper bases itself on
literature review from established disciplines like psychology,
sociology and philosophy regarding cognitive style, unlearning and
project success in general. The analysis and synthesis of literature in
the subject area a conceptual paper is utilized as the basis of future
research to form a comprehensive framework for project managers in
enhancing the project management competency.
Abstract: In this paper, the strength of a stabilizer is determined when the static and fatigue multiaxial loading are applied. Stabilizer is a part of suspension system in the heavy truck for stabilizing the cabin against the vibration of the road which composes of a thin-walled tube joined to a forge component by fillet weld. The component is loaded by non proportional random sequence of torsion and bending. Residual stress of welding process is considered here for static loading. This static loading with road irregularities are applied in this study as fatigue case that can affected in the fillet welded area of this part. The stresses in the welded structure are calculated using FEA. In addition, the fatigue with multi axial loading in the fillet weld is also investigated and the critical zone of the stabilizer is specified and presented by graphs. Residual stresses that have been resulted by the thermal forces are considered in FEA. Force increasing is the element of finding the critical point of the component.
Abstract: The hydro-mechanical model for unsaturated soils has
been presented based on the effective stress principle taking into
account effects of drying-wetting process. The elasto-plastic
constitutive equations for stress-strain relations of the soil skeleton
have been established. A plasticity model is modified from modified
Cam-Clay model. The hardening rule has been established by
considering the isotropic consolidation paths. The effect of dryingwetting
process is introduced through the ¤ç parameter. All model
coefficients are identified in terms of measurable parameters. The
simulations from the proposed model are compared with the
experimental results. The model calibration was performed to extract
the model parameter from the experimental results. Good agreement
between the results predicted using proposed model and the
experimental results was obtained.
Abstract: In this paper, the processing of sonar signals has been
carried out using Minimal Resource Allocation Network (MRAN)
and a Probabilistic Neural Network (PNN) in differentiation of
commonly encountered features in indoor environments. The
stability-plasticity behaviors of both networks have been
investigated. The experimental result shows that MRAN possesses
lower network complexity but experiences higher plasticity than
PNN. An enhanced version called parallel MRAN (pMRAN) is
proposed to solve this problem and is proven to be stable in
prediction and also outperformed the original MRAN.
Abstract: Previous studies have indicated that one of the most
critical failure reasons of enterprise systems is the lack of knowledge
sharing and utilization across organizations. As a consequence, many
information systems researchers have paid attention to examining the
effect of absorptive capacity closely associated with knowledge
sharing and transferring on IS usage performance. A lack of
communications and interactions due to a lack of organizational
citizenship behavior might lead to weak absorptive capacity and thus
negatively influence knowledge sharing across organizations. In this
study, a theoretical model which delves into the relationship between
usage performance of enterprise systems and its determinants was
established.
Abstract: This paper is devoted to a delayed periodic predatorprey system with non-monotonic numerical response on time scales. With the help of a continuation theorem based on coincidence degree theory, we establish easily verifiable criteria for the existence of multiple periodic solutions. As corollaries, some applications are listed. In particular, our results improve and generalize some known ones.
Abstract: Dengue, a disease found in most tropical and
subtropical areas of the world. It has become the most common
arboviral disease of humans. This disease is caused by any of four
serotypes of dengue virus (DEN1-DEN4). In many endemic
countries, the average age of getting dengue infection is shifting
upwards, dengue in pregnancy and infancy are likely to be
encountered more frequently. The dynamics of the disease is studied
by a compartmental model involving ordinary differential equations
for the pregnant, infant human and the vector populations. The
stability of each equilibrium point is given. The epidemic dynamic is
discussed. Moreover, the numerical results are shown for difference
values of dengue antibody.
Abstract: The present research was focused to investigate the
role of investment in the course of economic growth with reference to
Pakistan. The study analyzed the role of the public and private
investment and impact of the political and macroeconomic
uncertainty on economic growth of Pakistan by using the vector
autoregressive approach (VAR). In long-run both public and private
investment showed a positive impact on economic growth but the
growth was largely driven by private investment as compared to
public investment. Government consumption expenditure, economic
uncertainty and political instability hampered the economic growth of
Pakistan. In short-run the private investment positively influences the
growth but there was negative and insignificant effect of the public
investment and government consumption expenditure on the growth.
There was a positive relationship found between economic
uncertainty (proxy for inflation) and GDP in short run.
Abstract: In this paper, some new nonlinear generalized
Gronwall-Bellman-Type integral inequalities with mixed time delays
are established. These inequalities can be used as handy tools
to research stability problems of delayed differential and integral
dynamic systems. As applications, based on these new established
inequalities, some p-stable results of a integro-differential equation
are also given. Two numerical examples are presented to illustrate
the validity of the main results.
Abstract: Attempts to add fibre and polyphenols (PPs) into
popular beverages present challenges related to the properties of
finished products such as smoothies. Consumer acceptability,
viscosity and phenolic composition of smoothies containing high
levels of fruit fibre (2.5-7.5 g per 300 mL serve) and PPs (250-750
mg per 300 mL serve) were examined. The changes in total
extractable PP, vitamin C content, and colour of selected smoothies
over a storage stability trial (4°C, 14 days) were compared. A set of
acidic aqueous model beverages were prepared to further examine
the effect of two different heat treatments on the stability and
extractability of PPs. Results show that overall consumer
acceptability of high fibre and PP smoothies was low, with average
hedonic scores ranging from 3.9 to 6.4 (on a 1-9 scale). Flavour,
texture and overall acceptability decreased as fibre and polyphenol
contents increased, with fibre content exerting a stronger effect.
Higher fibre content resulted in greater viscosity, with an elevated PP
content increasing viscosity only slightly. The presence of fibre also
aided the stability and extractability of PPs after heating. A reduction
of extractable PPs, vitamin C content and colour intensity of
smoothies was observed after a 14-day storage period at 4°C. Two
heat treatments (75°C for 45 min or 85°C for 1 min) that are
normally used for beverage production, did not cause significant
reduction of total extracted PPs. It is clear that high levels of added
fibre and PPs greatly influence the consumer appeal of smoothies,
suggesting the need to develop novel formulation and processing
methods if a satisfactory functional beverage is to be developed
incorporating these ingredients.
Abstract: This paper presents a new stable robust adaptive controller and observer design for a class of nonlinear systems that contain i. Coupling of unmeasured states and unknown parameters ii. Unknown dead zone at the system actuator. The system is firstly cast into a modified form in which the observer and parameter estimation become feasible. Then a stable robust adaptive controller, state observer, parameter update laws are derived that would provide global adaptive system stability and desirable performance. To validate the approach, simulation was performed to a single-link mechanical system with a dynamic friction model and unknown dead zone exists at the system actuation. Then a comparison is presented with the results when there is no dead zone at the system actuation.
Abstract: In this paper the authors propose and verify an approach to control heat flow in machine tool components. Thermal deformations are a main aspect that affects the accuracy of machining. Due to goals of energy efficiency, thermal basic loads should be reduced. This leads to inhomogeneous and time variant temperature profiles. To counteract these negative consequences, material with high melting enthalpy is used as a method for thermal stabilization. The increased thermal capacity slows down the transient thermal behavior. To account for the delayed thermal equilibrium, a control mechanism for thermal flow is introduced. By varying a gap in a heat flow path the thermal resistance of an assembly can be controlled. This mechanism is evaluated in two experimental setups. First to validate the ability to control the thermal resistance and second to prove the possibility of a self-sufficient option based on the selfsensing abilities of thermal shape memory alloys.
Abstract: Mobile banking services present a unique growth
opportunity for mobile operators in emerging markets, and have
already made good progress in bringing financial services to the
previously unbanked populations of many developing countries. The
potential is amazing, but what about the risks? In the complex
process of establishing a mobile banking business model, many kinds
of risks and factors need to be monitored and well-managed. Risk
identification is the first stage of risk management. Correct risk
identification ensures risk management effectiveness. Keeping the
risks low makes it possible to use the full potential of mobile banking
and carry out the planned business strategy. The focus should be on
adoption of consumers which is the main risk factor of mobile
banking services.