Abstract: In designing of condensers, the prediction of pressure
drop is as important as the prediction of heat transfer coefficient.
Modeling of two phase flow, particularly liquid – vapor flow under
diabatic conditions inside a horizontal tube using CFD analysis is
difficult with the available two phase models in FLUENT due to
continuously changing flow patterns. In the present analysis, CFD
analysis of two phase flow of refrigerants inside a horizontal tube of
inner diameter, 0.0085 m and 1.2 m length is carried out using
homogeneous model under adiabatic conditions. The refrigerants
considered are R22, R134a and R407C. The analysis is performed at
different saturation temperatures and at different flow rates to
evaluate the local frictional pressure drop. Using Homogeneous
model, average properties are obtained for each of the refrigerants
that is considered as single phase pseudo fluid. The so obtained
pressure drop data is compared with the separated flow models
available in literature.
Abstract: Experimental data from an atmospheric air/water terrain slugging case has been made available by the Shell Amsterdam research center, and has been subject to numerical simulation and comparison with a one-dimensional two-phase slug tracking simulator under development at the Norwegian University of Science and Technology. The code is based on tracking of liquid slugs in pipelines by use of a Lagrangian grid formulation implemented in Cµ by use of object oriented techniques. An existing hybrid spatial discretization scheme is tested, in which the stratified regions are modelled by the two-fluid model. The slug regions are treated incompressible, thus requiring a single momentum balance over the whole slug. Upon comparison with the experimental data, the period of the simulated severe slugging cycle is observed to be sensitive to slug generation in the horizontal parts of the system. Two different slug initiation methods have been tested with the slug tracking code, and grid dependency has been investigated.
Abstract: This study examines the impact of working capital
management on firms- performance and market value of the firms in
Nigeria. A sample of fifty four non-financial quoted firms in Nigeria
listed on the Nigeria Stock Exchange was used for this study. Data
were collected from annual reports of the sampled firms for the
period 1995-2009. This result shows there is a significant negative
relationship between cash conversion cycle and market valuation
and firm-s performance. It also shows that debt ratio is positively
related to market valuation and negatively related firm-s
performance. The findings confirm that there is a significant
relationship between Market valuation, profitability and working
capital component in line with previous studies. This mean that
Nigeria firms should ensure adequate management of working
capital especially cash conversion cycle components of account
receivables, account payables and inventories, as efficiency working
capital management is expected to contribute positively to the firms-
market value.
Abstract: This paper proposes a novel stereo vision technique
for top view book scanners which provide us with dense 3d point
clouds of page surfaces. This is a precondition to dewarp bound
volumes independent of 2d information on the page. Our method is
based on algorithms, which normally require the projection of pattern
sequences with structured light. We use image sequences of the
moving stripe lighting of the top view scanner instead of an additional
light projection. Thus the stereo vision setup is simplified without
losing measurement accuracy. Furthermore we improve a surface
model dewarping method through introducing a difference vector
based on real measurements. Although our proposed method is hardly
expensive neither in calculation time nor in hardware requirements
we present good dewarping results even for difficult examples.
Abstract: Modern managements of water distribution system
(WDS) need water quality models that are able to accurately predict
the dynamics of water quality variations within the distribution system
environment. Before water quality models can be applied to solve
system problems, they should be calibrated. Although former
researchers use GA solver to calibrate relative parameters, it is
difficult to apply on the large-scale or medium-scale real system for
long computational time. In this paper a new method is designed
which combines both macro and detailed model to optimize the water
quality parameters. This new combinational algorithm uses radial
basis function (RBF) metamodeling as a surrogate to be optimized for
the purpose of decreasing the times of time-consuming water quality
simulation and can realize rapidly the calibration of pipe wall reaction
coefficients of chlorine model of large-scaled WDS. After two cases
study this method is testified to be more efficient and promising, and
deserve to generalize in the future.
Abstract: The separation of dissolved gas including dissolved oxygen can be used in breathing for a human under water. When one is suddenly wrecked or meets a tsunami, one is instantly drowned and cannot breathe under water. To avoid this crisis, when we meet waves, the dissolved gas separated from water by wave is used, while air can be used to breathe when we are about to escape from water. In this thesis, we investigated the separation characteristics of dissolved gas using the pipe type of hollow fiber membrane with polypropylene and the nude type of one with polysulfone. The hollow fiber membranes with good characteristics under water are used to separate the dissolved gas. The hollow fiber membranes with good characteristics in an air are used to transfer air. The combination of membranes with good separation characteristics under water and good transferring one in an air is used to breathe instantly under water to be alive at crisis. These results showed that polypropylene represented better performance than polysulfone under both of air and water conditions.
Abstract: In a nuclear reactor Loss of Coolant accident (LOCA)
considers wide range of postulated damage or rupture of pipe in the
heat transport piping system. In the case of LOCA with/without
failure of emergency core cooling system in a Pressurised Heavy
water Reactor, the Pressure Tube (PT) temperature could rise
significantly due to fuel heat up and gross mismatch of the heat
generation and heat removal in the affected channel. The extent and
nature of deformation is important from reactor safety point of view.
Experimental set-ups have been designed and fabricated to simulate
ballooning (radial deformation) of PT for 220 MWe IPHWRs.
Experiments have been conducted by covering the CT by ceramic
fibers and then by submerging CT in water of voided PTs. In both
the experiments, it is observed that ballooning initiates at a
temperature around 665´┐¢C and complete contact between PT and
Caldaria Tube (CT) occurs at around 700´┐¢C approximately. The
strain rate is found to be 0.116% per second. The structural integrity
of PT is retained (no breach) for all the experiments. The PT heatup
is found to be arrested after the contact between PT and CT, thus
establishing moderator acting as an efficient heat sink for IPHWRs.
Abstract: this paper presents a novel neural network controller
with composite adaptation low to improve the trajectory tracking
problems of biped robots comparing with classical controller. The
biped model has 5_link and 6 degrees of freedom and actuated by
Plated Pneumatic Artificial Muscle, which have a very high power to
weight ratio and it has large stoke compared to similar actuators. The
proposed controller employ a stable neural network in to approximate
unknown nonlinear functions in the robot dynamics, thereby
overcoming some limitation of conventional controllers such as PD
or adaptive controllers and guarantee good performance. This NN
controller significantly improve the accuracy requirements by
retraining the basic PD/PID loop, but adding an inner adaptive loop
that allows the controller to learn unknown parameters such as
friction coefficient, therefore improving tracking accuracy.
Simulation results plus graphical simulation in virtual reality show
that NN controller tracking performance is considerably better than
PD controller tracking performance.
Abstract: An advanced Monte Carlo simulation method, called Subset Simulation (SS) for the time-dependent reliability prediction for underground pipelines has been presented in this paper. The SS can provide better resolution for low failure probability level with efficient investigating of rare failure events which are commonly encountered in pipeline engineering applications. In SS method, random samples leading to progressive failure are generated efficiently and used for computing probabilistic performance by statistical variables. SS gains its efficiency as small probability event as a product of a sequence of intermediate events with larger conditional probabilities. The efficiency of SS has been demonstrated by numerical studies and attention in this work is devoted to scrutinise the robustness of the SS application in pipe reliability assessment. It is hoped that the development work can promote the use of SS tools for uncertainty propagation in the decision-making process of underground pipelines network reliability prediction.
Abstract: This paper looks into detailed investigation of
thermal-hydraulic characteristics of the flow field in a fuel rod
model, especially near the spacer. The area investigate represents a
source of information on the velocity flow field, vortex, and on the
amount of heat transfer into the coolant all of which are critical for
the design and improvement of the fuel rod in nuclear power plants.
The flow field investigation uses three-dimensional Computational
Fluid Dynamics (CFD) with the Reynolds stresses turbulence model
(RSM). The fuel rod model incorporates a vertical annular channel
where three different shapes of spacers are used; each spacer shape is
addressed individually. These spacers are mutually compared in
consideration of heat transfer capabilities between the coolant and
the fuel rod model. The results are complemented with the calculated
heat transfer coefficient in the location of the spacer and along the
stainless-steel pipe.
Abstract: This study was to investigate the performance of
hybrid solvents blended between primary, secondary, or tertiary
amines and piperazine (PZ) for CO2 removal from flue gas in terms
of CO2 absorption capacity and regeneration efficiency at 90 oC.
Alkanolamines used in this work were monoethanolamine (MEA),
diethanolamine (DEA), and triethanolamine (TEA). The CO2
absorption was experimentally examined under atmospheric pressure
and room temperature. The results show that MEA blend with PZ
provided the maximum CO2 absorption capacity of 0.50 mol
CO2/mol amine while TEA provided the minimum CO2 absorption
capacity of 0.30 mol CO2/mol amine. TEA was easier to regenerate
for both first cycle and second cycle with less loss of absorption
capacity. The regeneration efficiency of TEA was 95.09 and 92.89 %,
for the first and second generation cycles, respectively.
Abstract: It is claimed that a new style of urban planning and
policy intertwined with ICT is emerging and urban planning and ICT
policy are no longer considered as separate disciplines. The
interactions between electronic spaces and urban spaces are so
complex and uncertain that confront urban planners and policy makers
with great challenges. However, the assumption about the relationship
between ICT and urban planning is mainly based on North American
and European experiences. In the light of empirical evidence from
Taipei City, this paper shows that this new type of urban planning and
policy intertwined with ICT has existed in Asian city for a decade as
well. Based on these results, this paper further reviews how the Taipei
City government implements this new type of urban ICT planning and
the validity and realism of its underlying assumptions. Finally, it also
explores the extent to which urban ICT planning could promote
positive synergies between physical and electronic developments.
Abstract: If an unsteady heat transfer or heat impulse happens in
part of the cryogenic pipeline system of large space environment
simulation equipment while running in vacuum environment, it will
lead to abnormal flow of the cryogenic fluid in the pipeline. When the
situation gets worse, the cryogenic fluid in the pipeline will have phase
change and a gas block which results in the malfunction of the
cryogenic pipeline system. Referring to the structural parameter of a
typical cryogenic pipeline system and the basic equation, an analytical
model and a calculation model for cryogenic pipeline system can be
built. The various factors which influence the thermal resistance of a
cryogenic pipeline system can be analyzed and calculated by using the
qualitative analysis relation deduced for thermal resistance of pipeline.
The research conclusion could provide theoretical support for the
design and operation of a cryogenic pipeline system
Abstract: This paper describes the architecture for a collaborative Car Pooling System based on a credits mechanism to motivate the cooperation among users. Users can spend the accumulated credits on parking facilities. For this, we propose a business model to support the collaboration between a car pooling system and parking facilities. The Portuguese Lisbon-s Metropolitan area is used as application scenario.
Abstract: The sanitary sewerage connection rate becomes an
important indicator of advanced cities. Following the construction of
sanitary sewerages, the maintenance and management systems are
required for keeping pipelines and facilities functioning well. These
maintenance tasks often require sewer workers to enter the manholes
and the pipelines, which are confined spaces short of natural
ventilation and full of hazardous substances. Working in sewers could
be easily exposed to a risk of adverse health effects. This paper
proposes the use of Bayesian belief networks (BBN) as a higher level
of noncarcinogenic health risk assessment of sewer workers. On the
basis of the epidemiological studies, the actual hospital attendance
records and expert experiences, the BBN is capable of capturing the
probabilistic relationships between the hazardous substances in sewers
and their adverse health effects, and accordingly inferring the
morbidity and mortality of the adverse health effects. The provision of
the morbidity and mortality rates of the related diseases is more
informative and can alleviate the drawbacks of conventional methods.
Abstract: Most simple nonlinear thresholding rules for
wavelet- based denoising assume that the wavelet coefficients are independent. However, wavelet coefficients of natural images have significant dependencies. This paper attempts to give a recipe for selecting one of the popular image-denoising algorithms based
on VisuShrink, SureShrink, OracleShrink, BayesShrink and BiShrink and also this paper compares different Bivariate models used for image denoising applications. The first part of the paper
compares different Shrinkage functions used for image-denoising.
The second part of the paper compares different bivariate models
and the third part of this paper uses the Bivariate model with modified marginal variance which is based on Laplacian assumption. This paper gives an experimental comparison on six 512x512 commonly used images, Lenna, Barbara, Goldhill,
Clown, Boat and Stonehenge. The following noise powers 25dB,26dB, 27dB, 28dB and 29dB are added to the six standard images and the corresponding Peak Signal to Noise Ratio (PSNR) values
are calculated for each noise level.
Abstract: This work presents an approach for the measurement
of mutual inductance on near field inductive coupling. The mutual
inductance between inductive circuits allows the simulation of energy
transfer from reader to tag, that can be used in RFID and powerless
implantable devices. It also allows one to predict the maximum
voltage in the tag of the radio-frequency system.
Abstract: Policies that support entrepreneurship are keys to the
generation of new business. In Brazil, seed capital, installation of
technology parks, programs and zero interest financing, economic
subsidy as Program First Innovative Company (PRIME) are
examples of incentive policies. For the implementation of PRIME, in
particular the Brazilian Innovation Agency (FINEP) decentralized
operationalization so that business incubators could select innovative
projects. This paper analyzes the program PRIME Business Incubator
Center of the State of Sergipe (CISE) after calculating the mean and
standard deviation of the grades obtained by companies in the factors
of innovation, market potential, financial return economic, market
strategy and staff and application of the Mann-Whitney test.
Abstract: Tubular linear induction motor (TLIM) can be used as a capsule pump in a large pneumatic capsule pipeline (PCP) system. Parametric performance evaluation of the designed 1-meter diameter PCP-TLIM system yields encouraging results for practical implementation. The capsule thrust and speed inside the TLIM pump can be calculated from the combination of the PCP fluid mechanics and the TLIM equations. The TLIM equivalent circuits derived from those of the conventional three-phase induction motor are used as a model to predict the static test results of a small-scale PCP-TLIM system. In this paper, additional dynamic tests are performed on the same small-scale PCP-TLIM system with two capsules of different diameters. The behaviors of the capsule inside the pump are observed and analyzed. The dynamic performances from the dynamic tests are compared with the theoretical predictions based on the TLIM equivalent circuit model.
Abstract: The pipe inspection operation is the difficult detective
performance. Almost applications are mainly relies on a manual
recognition of defective areas that have carried out detection by an
engineer. Therefore, an automation process task becomes a necessary
in order to avoid the cost incurred in such a manual process. An
automated monitoring method to obtain a complete picture of the
sewer condition is proposed in this work. The focus of the research is
the automated identification and classification of discontinuities in
the internal surface of the pipe. The methodology consists of several
processing stages including image segmentation into the potential
defect regions and geometrical characteristic features. Automatic
recognition and classification of pipe defects are carried out by means
of using an artificial neural network technique (ANN) based on
Radial Basic Function (RBF). Experiments in a realistic environment
have been conducted and results are presented.