Abstract: The sand production problem has led researchers into making various attempts to understand the phenomenon. The generally accepted concept is that the occurrence of sanding is due to the in-situ stress conditions and the induced changes in stress that results in the failure of the reservoir sandstone during hydrocarbon production from wellbores. By using a hypothetical cased (perforated) well, an approach to the problem is presented here by using Finite Element numerical modelling techniques. In addition to the examination of the erosion problem, the influence of certain key parameters is studied in order to ascertain their effect on the failure and subsequent erosion process. The major variables investigated include: drawdown, perforation depth, and the erosion criterion. Also included is the determination of the optimal mud pressure for given operational and reservoir conditions. The improved understanding between parameters enables the choice of optimal values to minimize sanding during oil production.
Abstract: Wireless Sensor Networks (WSN) are emerging
because of the developments in wireless communication technology and miniaturization of the hardware. WSN consists of a large number of low-cost, low-power, multifunctional sensor nodes to monitor physical conditions, such as temperature, sound, vibration, pressure,
motion, etc. The MAC protocol to be used in the sensor networks must be energy efficient and this should aim at conserving the energy during its operation. In this paper, with the focus of analyzing the
MAC protocols used in wireless Adhoc networks to WSN, simulation
experiments were conducted in Global Mobile Simulator
(GloMoSim) software. Number of packets sent by regular nodes, and received by sink node in different deployment strategies, total energy
spent, and the network life time have been chosen as the metric for comparison. From the results of simulation, it is evident that the IEEE 802.11 protocol performs better compared to CSMA and MACA protocols.
Abstract: The localized corrosion behavior of laser surface
melted 304L austenitic stainless steel was studied by
potentiodynamic polarization test. The extent of improvement in
corrosion resistance was governed by the preferred orientation and
the percentage of delta ferrite present on the surface of the laser
melted sample. It was established by orientation imaging microscopy
that the highest pitting potential value was obtained when grains were
oriented in the most close- packed [101] direction compared to the
random distribution of the base metal and other laser surface melted
samples oriented in [001] direction. The sample with lower
percentage of ferrite had good pitting resistance.
Abstract: Throughout this paper, a relatively new technique, the Tabu search variable selection model, is elaborated showing how it can be efficiently applied within the financial world whenever researchers come across the selection of a subset of variables from a whole set of descriptive variables under analysis. In the field of financial prediction, researchers often have to select a subset of variables from a larger set to solve different type of problems such as corporate bankruptcy prediction, personal bankruptcy prediction, mortgage, credit scoring and the Arbitrage Pricing Model (APM). Consequently, to demonstrate how the method operates and to illustrate its usefulness as well as its superiority compared to other commonly used methods, the Tabu search algorithm for variable selection is compared to two main alternative search procedures namely, the stepwise regression and the maximum R 2 improvement method. The Tabu search is then implemented in finance; where it attempts to predict corporate bankruptcy by selecting the most appropriate financial ratios and thus creating its own prediction score equation. In comparison to other methods, mostly the Altman Z-Score model, the Tabu search model produces a higher success rate in predicting correctly the failure of firms or the continuous running of existing entities.
Abstract: In recent years, most of the regions in the world are
exposed to degradation and erosion caused by increasing
population and over use of land resources. The understanding of
the most important factors on soil erosion and sediment yield are
the main keys for decision making and planning. In this study, the
sediment yield and soil erosion were estimated and the priority of
different soil erosion factors used in the MPSIAC method of soil
erosion estimation is evaluated in AliAbad watershed in southwest
of Isfahan Province, Iran. Different information layers of the
parameters were created using a GIS technique. Then, a
multivariate procedure was applied to estimate sediment yield and
to find the most important factors of soil erosion in the model. The
results showed that land use, geology, land and soil cover are the
most important factors describing the soil erosion estimated by
MPSIAC model.
Abstract: The Goursat partial differential equation arises in
linear and non linear partial differential equations with mixed
derivatives. This equation is a second order hyperbolic partial
differential equation which occurs in various fields of study such as
in engineering, physics, and applied mathematics. There are many
approaches that have been suggested to approximate the solution of
the Goursat partial differential equation. However, all of the
suggested methods traditionally focused on numerical differentiation
approaches including forward and central differences in deriving the
scheme. An innovation has been done in deriving the Goursat partial
differential equation scheme which involves numerical integration
techniques. In this paper we have developed a new scheme to solve
the Goursat partial differential equation based on the Adomian
decomposition (ADM) and associated with Boole-s integration rule to
approximate the integration terms. The new scheme can easily be
applied to many linear and non linear Goursat partial differential
equations and is capable to reduce the size of computational work.
The accuracy of the results reveals the advantage of this new scheme
over existing numerical method.
Abstract: The main purpose of this paper is to research on the
methodologies of BYD to implement the opportune innovation. BYD
is a Chinese company which has the IT component manufacture, the
rechargeable battery and the automobile businesses. The paper deals
with the innovation methodology as the same as the IPR management
BYD implements in order to obtain the rapid growth of technology
development with the reasonable cost of money and time.
Abstract: We propose a decoy-pulse protocol for frequency-coded implementation of B92 quantum key distribution protocol. A direct extension of decoy-pulse method to frequency-coding scheme results in security loss as an eavesdropper can distinguish between signal and decoy pulses by measuring the carrier photon number without affecting other statistics. We overcome this problem by optimizing the ratio of carrier photon number of decoy-to-signal pulse to be as close to unity as possible. In our method the switching between signal and decoy pulses is achieved by changing the amplitude of RF signal as opposed to modulating the intensity of optical signal thus reducing system cost. We find an improvement by a factor of 100 approximately in the key generation rate using decoy-state protocol. We also study the effect of source fluctuation on key rate. Our simulation results show a key generation rate of 1.5×10-4/pulse for link lengths up to 70km. Finally, we discuss the optimum value of average photon number of signal pulse for a given key rate while also optimizing the carrier ratio.
Abstract: As the Computed Tomography(CT) requires normally
hundreds of projections to reconstruct the image, patients are exposed
to more X-ray energy, which may cause side effects such as cancer.
Even when the variability of the particles in the object is very less,
Computed Tomography requires many projections for good quality
reconstruction. In this paper, less variability of the particles in an
object has been exploited to obtain good quality reconstruction.
Though the reconstructed image and the original image have same
projections, in general, they need not be the same. In addition
to projections, if a priori information about the image is known,
it is possible to obtain good quality reconstructed image. In this
paper, it has been shown by experimental results why conventional
algorithms fail to reconstruct from a few projections, and an efficient
polynomial time algorithm has been given to reconstruct a bi-level
image from its projections along row and column, and a known sub
image of unknown image with smoothness constraints by reducing the
reconstruction problem to integral max flow problem. This paper also
discusses the necessary and sufficient conditions for uniqueness and
extension of 2D-bi-level image reconstruction to 3D-bi-level image
reconstruction.
Abstract: In this paper, an effective sliding mode design is
applied to chaos synchronization. The proposed controller can make
the states of two identical modified Chua-s circuits globally
asymptotically synchronized. Numerical results are provided to show
the effectiveness and robustness of the proposed method.
Abstract: This paper focuses on analyzing medical diagnostic data using classification rules in data mining and context reduction in formal concept analysis. It helps in finding redundancies among the various medical examination tests used in diagnosis of a disease. Classification rules have been derived from positive and negative association rules using the Concept lattice structure of the Formal Concept Analysis. Context reduction technique given in Formal Concept Analysis along with classification rules has been used to find redundancies among the various medical examination tests. Also it finds out whether expensive medical tests can be replaced by some cheaper tests.
Abstract: A new SUZ-4 zeolite membrane with
tetraethlyammonium hydroxide as the template was fabricated on
mullite tube via hydrothermal sol-gel synthesis in a rotating
autoclave reactor. The suitable synthesis condition was SiO2:Al2O3
ratio of 21.2 for 4 days at 155 °C crystallization under autogenous
pressure. The obtained SUZ-4 possessed a high BET surface area of
396.4 m2/g, total pore volume at 2.611 cm3/g, and narrow pore size
distribution with 97 nm mean diameter and 760 nm long of needle
crystal shape. The SUZ-4 layer obtained from seeding crystallization
was thicker than that of without seeds or in situ crystallization.
Abstract: Modeling product configurations needs large amounts of knowledge about technical and marketing restrictions on the product. Previous attempts to automate product configurations concentrate on representations and management of the knowledge for specific domains in fixed and isolated computing environments. Since the knowledge about product configurations is subject to continuous change and hard to express, these attempts often failed to efficiently manage and exchange the knowledge in collaborative product development. In this paper, XML Topic Map (XTM) is introduced to represent and exchange the knowledge about product configurations in collaborative product development. A product configuration model based on XTM along with its merger and inference facilities enables configuration engineers in collaborative product development to manage and exchange their knowledge efficiently. A prototype implementation is also presented to demonstrate the proposed model can be applied to engineering information systems to exchange the product configuration knowledge.
Abstract: Tanzania is a developing country, which significantly lags behind the rest of the world in information communications technology (ICT), especially for the Internet. Internet connectivity to the rest of the world is via expensive satellite links, thus leaving the majority of the population unable to access the Internet due to the high cost. This paper introduces the concept of an optical WDM network for Internet infrastructure in Tanzania, so as to reduce Internet connection costs, and provide Internet access to the majority of people who live in both urban and rural areas. We also present a proposed optical WDM network, which mitigates the effects of system impairments, and provide simulation results to show that the data is successfully transmitted over a longer distance using a WDM network.
Abstract: This paper describes the design and results of FROID,
an outbound intrusion detection system built with agent technology
and supported by an attacker-centric ontology. The prototype
features a misuse-based detection mechanism that identifies remote
attack tools in execution. Misuse signatures composed of attributes
selected through entropy analysis of outgoing traffic streams and
process runtime data are derived from execution variants of attack
programs. The core of the architecture is a mesh of self-contained
detection cells organized non-hierarchically that group agents in a
functional fashion. The experiments show performance gains when
the ontology is enabled as well as an increase in accuracy achieved
when correlation cells combine detection evidence received from
independent detection cells.
Abstract: Liver segmentation is the first significant process for
liver diagnosis of the Computed Tomography. It segments the liver
structure from other abdominal organs. Sophisticated filtering techniques
are indispensable for a proper segmentation. In this paper, we
employ a 3D anisotropic diffusion as a preprocessing step. While
removing image noise, this technique preserve the significant parts
of the image, typically edges, lines or other details that are important
for the interpretation of the image. The segmentation task is done
by using thresholding with automatic threshold values selection and
finally the false liver region is eliminated using 3D connected component.
The result shows that by employing the 3D anisotropic filtering,
better liver segmentation results could be achieved eventhough simple
segmentation technique is used.
Abstract: A great deal of research works in the field information
systems security has been based on a positivist paradigm. Applying
the reductionism concept of the positivist paradigm for information
security means missing the bigger picture and thus, the lack of holism
which could be one of the reasons why security is still overlooked,
comes as an afterthought or perceived from a purely technical
dimension. We need to reshape our thinking and attitudes towards
security especially in a complex and dynamic environment such as e-
Business to develop a holistic understanding of e-Business security in
relation to its context as well as considering all the stakeholders in
the problem area. In this paper we argue the suitability and need for
more inductive interpretive approach and qualitative research method
to investigate e-Business security. Our discussion is based on a
holistic framework of enquiry, nature of the research problem, the
underling theoretical lens and the complexity of e-Business
environment. At the end we present a research strategy for
developing a holistic framework for understanding of e-Business
security problems in the context of developing countries based on an
interdisciplinary inquiry which considers their needs and
requirements.
Abstract: Accurate timing alignment and stability is important
to maximize the true counts and minimize the random counts in
positron emission tomography So signals output from detectors must
be centering with the two isotopes to pre-operation and fed signals
into four units of pulse-processing units, each unit can accept up to
eight inputs. The dual source computed tomography consist two units
on the left for 15 detector signals of Cs-137 isotope and two units on
the right are for 15 detectors signals of Co-60 isotope. The gamma
spectrum consisting of either single or multiple photo peaks. This
allows for the use of energy discrimination electronic hardware
associated with the data acquisition system to acquire photon counts
data with a specific energy, even if poor energy resolution detectors
are used. This also helps to avoid counting of the Compton scatter
counts especially if a single discrete gamma photo peak is emitted by
the source as in the case of Cs-137. In this study the polyenergetic
version of the alternating minimization algorithm is applied to the
dual energy gamma computed tomography problem.
Abstract: Dynamic models of power converters are normally
time-varying because of their switching actions. Several approaches
are applied to analyze the power converters to achieve the timeinvariant
models suitable for system analysis and design via the
classical control theory. The paper presents how to derive dynamic
models of the power system consisting of a three-phase controlled
rectifier feeding an uncontrolled buck converter by using the
combination between the well known techniques called the DQ and
the generalized state-space averaging methods. The intensive timedomain
simulations of the exact topology model are used to support
the accuracies of the reported model. The results show that the
proposed model can provide good accuracies in both transient and
steady-state responses.
Abstract: In this study, oxidative steam reforming of methanol (OSRM) over a Au/CeO2–Fe2O3 catalyst prepared by a depositionprecipitation (DP) method was studied to produce hydrogen in order to feed a Proton Exchange Membrane Fuel Cell (PEMFC). The support (CeO2, Fe2O3, and CeO2–Fe2O3) were prepared by precipitation and co-precipitation methods. The impact of the support composition on the catalytic performance was studied by varying the Ce/(Ce+Fe) atomic ratio, it was found that the 1%Au/CF(0.25) calcined at 300 °C exhibited the highest catalytic activity in the whole temperature studied. In addition, the effect of Au content was investigated and 3%Au/CF(0.25) exhibited the highest activity under the optimum condition in the temperature range of 200 °C to 400 °C. The catalysts were characterized by various techniques: XRD, TPR, XRF, and UV-vis.