Abstract: The source of the jet noise is generated by rocket exhaust plume during rocket engine testing. A domain decomposition approach is applied to the jet noise prediction in this paper. The aerodynamic noise coupling is based on the splitting into acoustic sources generation and sound propagation in separate physical domains. Large Eddy Simulation (LES) is used to simulate the supersonic jet flow. Based on the simulation results of the flow-fields, the jet noise distribution of the sound pressure level is obtained by applying the Ffowcs Williams-Hawkings (FW-H) acoustics equation and Fourier transform. The calculation results show that the complex structures of expansion waves, compression waves and the turbulent boundary layer could occur due to the strong interaction between the gas jet and the ambient air. In addition, the jet core region, the shock cell and the sound pressure level of the gas jet increase with the nozzle size increasing. Importantly, the numerical simulation results of the far-field sound are in good agreement with the experimental measurements in directivity.
Abstract: With 40% of total world energy consumption,
building systems are developing into technically complex large
energy consumers suitable for application of sophisticated power
management approaches to largely increase the energy efficiency
and even make them active energy market participants. Centralized
control system of building heating and cooling managed by
economically-optimal model predictive control shows promising
results with estimated 30% of energy efficiency increase. The research
is focused on implementation of such a method on a case study
performed on two floors of our faculty building with corresponding
sensors wireless data acquisition, remote heating/cooling units and
central climate controller. Building walls are mathematically modeled
with corresponding material types, surface shapes and sizes. Models
are then exploited to predict thermal characteristics and changes in
different building zones. Exterior influences such as environmental
conditions and weather forecast, people behavior and comfort
demands are all taken into account for deriving price-optimal climate
control. Finally, a DC microgrid with photovoltaics, wind turbine,
supercapacitor, batteries and fuel cell stacks is added to make the
building a unit capable of active participation in a price-varying
energy market. Computational burden of applying model predictive
control on such a complex system is relaxed through a hierarchical
decomposition of the microgrid and climate control, where the
former is designed as higher hierarchical level with pre-calculated
price-optimal power flows control, and latter is designed as lower
level control responsible to ensure thermal comfort and exploit
the optimal supply conditions enabled by microgrid energy flows
management. Such an approach is expected to enable the inclusion
of more complex building subsystems into consideration in order to
further increase the energy efficiency.
Abstract: The cities of Johannesburg and Pretoria both located in the Gauteng province are separated by a distance of 58 km. The traffic queues on the Ben Schoeman freeway which connects these two cities can stretch for almost 1.5 km. Vehicle traffic congestion impacts negatively on the business and the commuter’s quality of life. The goal of this paper is to identify variables that influence the flow of traffic and to design a vehicle traffic prediction model, which will predict the traffic flow pattern in advance. The model will unable motorist to be able to make appropriate travel decisions ahead of time. The data used was collected by Mikro’s Traffic Monitoring (MTM). Multi-Layer perceptron (MLP) was used individually to construct the model and the MLP was also combined with Bagging ensemble method to training the data. The cross—validation method was used for evaluating the models. The results obtained from the techniques were compared using predictive and prediction costs. The cost was computed using combination of the loss matrix and the confusion matrix. The predicted models designed shows that the status of the traffic flow on the freeway can be predicted using the following parameters travel time, average speed, traffic volume and day of month. The implications of this work is that commuters will be able to spend less time travelling on the route and spend time with their families. The logistics industry will save more than twice what they are currently spending.
Abstract: Patient-specific models are instance-based learning
algorithms that take advantage of the particular features of the patient
case at hand to predict an outcome. We introduce two patient-specific
algorithms based on decision tree paradigm that use AUC as a
metric to select an attribute. We apply the patient specific algorithms
to predict outcomes in several datasets, including medical datasets.
Compared to the patient-specific decision path (PSDP) entropy-based
and CART methods, the AUC-based patient-specific decision path
models performed equivalently on area under the ROC curve (AUC).
Our results provide support for patient-specific methods being a
promising approach for making clinical predictions.
Abstract: This paper discusses the applicability of the numerical model for a damage prediction method of the accidental hydrogen explosion occurring in a hydrogen facility. The numerical model was based on an unstructured finite volume method (FVM) code “NuFD/FrontFlowRed”. For simulating unsteady turbulent combustion of leaked hydrogen gas, a combination of Large Eddy Simulation (LES) and a combustion model were used. The combustion model was based on a two scalar flamelet approach, where a G-equation model and a conserved scalar model expressed a propagation of premixed flame surface and a diffusion combustion process, respectively. For validation of this numerical model, we have simulated the previous two types of hydrogen explosion tests. One is open-space explosion test, and the source was a prismatic 5.27 m3 volume with 30% of hydrogen-air mixture. A reinforced concrete wall was set 4 m away from the front surface of the source. The source was ignited at the bottom center by a spark. The other is vented enclosure explosion test, and the chamber was 4.6 m × 4.6 m × 3.0 m with a vent opening on one side. Vent area of 5.4 m2 was used. Test was performed with ignition at the center of the wall opposite the vent. Hydrogen-air mixtures with hydrogen concentrations close to 18% vol. were used in the tests. The results from the numerical simulations are compared with the previous experimental data for the accuracy of the numerical model, and we have verified that the simulated overpressures and flame time-of-arrival data were in good agreement with the results of the previous two explosion tests.
Abstract: Data fusion technology can be the best way to extract
useful information from multiple sources of data. It has been widely
applied in various applications. This paper presents a data fusion
approach in multimedia data for event detection in twitter by using
Dempster-Shafer evidence theory. The methodology applies a mining
algorithm to detect the event. There are two types of data in the
fusion. The first is features extracted from text by using the bag-ofwords
method which is calculated using the term frequency-inverse
document frequency (TF-IDF). The second is the visual features
extracted by applying scale-invariant feature transform (SIFT). The
Dempster - Shafer theory of evidence is applied in order to fuse the
information from these two sources. Our experiments have indicated
that comparing to the approaches using individual data source, the
proposed data fusion approach can increase the prediction accuracy
for event detection. The experimental result showed that the proposed
method achieved a high accuracy of 0.97, comparing with 0.93 with
texts only, and 0.86 with images only.
Abstract: This paper looks at healing performances as
ethnographic expressions of local knowledge and culture embedded
within the Malay psyche and gemeinschaft. As society develops and
progresses, these healing performances are caught within conflicting
trajectories which become compounded by the contestations of
tradition, religious concerns, locality and modernity. As
exemplifications of the Malay ethos, these performances practice
common rituals, cater to the innate needs of the practitioners and
serve the targeted, closed, local community. This paper traces the
ethnographic methods in documenting these practices as rituals of
healing in a post-modern world. It delineates the ethnographic
concepts used to analyze these rituals, and to semiotically read the
varied binarial oppositions and juxtapositions. The paper concludes
by highlighting the reconciliatory processes involved in maintaining
these ritual performances as exemplifications of the Malay ethos
playing an important role in the re-aligning, re-balancing and healing
of the Malay community’s psyche.
Abstract: Energy consumption data, in particular those involving
public buildings, are impacted by many factors: the building structure,
climate/environmental parameters, construction, system operating
condition, and user behavior patterns. Traditional methods for data
analysis are insufficient. This paper delves into the data mining
technology to determine its application in the analysis of building
energy consumption data including energy consumption prediction,
fault diagnosis, and optimal operation. Recent literature are reviewed
and summarized, the problems faced by data mining technology in the
area of energy consumption data analysis are enumerated, and research
points for future studies are given.
Abstract: In the deep south of Thailand, checkpoints for people
verification are necessary for the security management of risk zones,
such as official buildings in the conflict area. In this paper, we
propose an automatic checkpoint system that verifies persons using
information from ID cards and facial features. The methods for a
person’s information abstraction and verification are introduced
based on useful information such as ID number and name, extracted
from official cards, and facial images from videos. The proposed
system shows promising results and has a real impact on the local
society.
Abstract: This paper aims to link together the concepts of job
satisfaction, work engagement, trust, job meaningfulness and loyalty
to the organisation focusing on specific type of employment –
academic jobs. The research investigates the relationships between
job satisfaction, work engagement and loyalty as well as the impact
of trust and job meaningfulness on the work engagement and loyalty.
The survey was conducted in one of the largest Latvian higher
education institutions and the sample was drawn from academic staff
(n=326). Structured questionnaire with 44 reflective type questions
was developed to measure the constructs. Data was analysed using
SPSS and Smart-PLS software. Variance based structural equation
modelling (PLS-SEM) technique was used to test the model and to
predict the most important factors relevant to employee engagement
and loyalty. The first order model included two endogenous
constructs (loyalty and intention to stay and recommend to work in
this organisation, and employee engagement), as well as six
exogenous constructs (feeling of fair treatment and trust in
management; career growth opportunities; compensation, pay and
benefits; management; colleagues and teamwork; and finally job
meaningfulness). Job satisfaction was developed as second order
construct and both: first and second order models were designed for
data analysis. It was found that academics are more engaged than
satisfied with their work and main reason for that was found to be job
meaningfulness, which is significant predictor for work engagement,
but not for job satisfaction. Compensation is not significantly related
to work engagement, but only to job satisfaction. Trust was not
significantly related neither to engagement, nor to satisfaction,
however, it appeared to be significant predictor of loyalty and
intentions to stay with the University. Paper revealed academic jobs
as specific kind of employment where employees can be more
engaged than satisfied and highlighted the specific role of job
meaningfulness in the University settings.
Abstract: In this current contribution, authors are dedicated to
investigate influence of the crystal lamellae orientation on
electromechanical behaviors of relaxor ferroelectric Poly
(vinylidene fluoride –trifluoroethylene -chlorotrifluoroethylene)
(P(VDF-TrFE-CTFE)) films by control of polymer microstructure,
aiming to picture the full map of structure-property relationship. In
order to define their crystal orientation films, terpolymer films were
fabricated by solution-casting, stretching and hot-pressing process.
Differential scanning calorimetry, impedance analyzer, and tensile
strength techniques were employed to characterize crystallographic
parameters, dielectric permittivity, and elastic Young’s modulus
respectively. In addition, large electrical induced out-of-plane
electrostrictive strain was obtained by cantilever beam mode.
Consequently, as-casted pristine films exhibited surprisingly high
electrostrictive strain 0.1774% due to considerably small value of
elastic Young’s modulus although relatively low dielectric
permittivity. Such reasons contributed to large mechanical elastic
energy density. Instead, due to 2 folds increase of elastic Young’s
modulus and less than 50% augmentation of dielectric constant, fullycrystallized
film showed weak electrostrictive behavior and
mechanical energy density as well. And subjected to mechanical
stretching process, Film C exhibited stronger dielectric constant and
out-performed electrostrictive strain over Film B because edge-on
crystal lamellae orientation induced by uniaxially mechanical stretch.
Hot-press films were compared in term of cooling rate. Rather large
electrostrictive strain of 0.2788% for hot-pressed Film D in
quenching process was observed although its dielectric permittivity
equivalent to that of pristine as-casted Film A, showing highest
mechanical elastic energy density value of 359.5 J/m3. In hot-press
cooling process, dielectric permittivity of Film E saw values at 48.8
concomitant with ca.100% increase of Young’s modulus. Films with
intermediate mechanical energy density were obtained.
Abstract: E-government has been adopted and used by many governments/countries around the world including Ghana to provide citizens and businesses with more accurate, real-time, and high quality services and information. The objective of this paper is to present an overview of the Government of Ghana’s (GoG) adoption and implement of e-government and its usage by the Ministries, Departments and its agencies (MDAs) as well as other public sector institutions to deliver efficient public service to the general public i.e. citizens, business etc. Government implementation of e-government focused on facilitating effective delivery of government service to the public and ultimately to provide efficient government-wide electronic means of sharing information and knowledge through a network infrastructure developed to connect all major towns and cities, Ministries, Departments and Agencies and other public sector organizations in Ghana. One aim for the Government of Ghana use of ICT in public administration is to improve productivity in government administration and service by facilitating exchange of information to enable better interaction and coordination of work among MDAs, citizens and private businesses. The study was prepared using secondary sources of data from government policy documents, national and international published reports, journal articles, and web sources. This study indicates that through the e-government initiative, currently citizens and businesses can access and pay for services such as renewal of driving license, business registration, payment of taxes, acquisition of marriage and birth certificates as well as application for passport through the GoG electronic service (eservice) and electronic payment (epay) portal. Further, this study shows that there is enormous commitment from GoG to adopt and implement e-government as a tool not only to transform the business of government but also to bring efficiency in public services delivered by the MDAs. To ascertain this, a further study need to be carried out to determine if the use of e-government has brought about the anticipated improvements and efficiency in service delivery of MDAs and other state institutions in Ghana.
Abstract: This paper explored the challenges faced by the
management of a Ghanaian state enterprise in managing conflicts and
disturbances associated with its attempt to implement new work
practices to enhance its capability to operate as a commercial entity.
The purpose was to understand the extent to which organizational
involvement, consistency and adaptability influence employees’
consumption of new work practices in transforming the
organization’s organizational activity system. Using selfadministered
questionnaires, data were collected from one hundred
and eighty (180) employees and analyzed using both descriptive and
inferential statistics. The results showed that constraints in
organizational involvement and adaptability prevented the positive
consumption of new work practices by employees in the
organization. It is also found that the organization’s employees failed
to consume the new practices being implemented, because they
perceived the process as non-involving, and as such, did not
encourage the development of employee capability, empowerment,
and teamwork. The study concluded that the failure of the
organization’s management to create opportunities for organizational
learning constrained its ability to get employees consume the new
work practices, which situation could have facilitated the
organization’s capabilities of operating as a commercial entity.
Abstract: This paper presents the experimental results of 11 kV
and 33 kV silicon composite insulators under artificial salt and urea
polluted conditions. The tests were carried out under different
seasons like summer, winter, and monsoon. The artificial pollution is
prepared by properly dissolving the salt and urea in the water. The
prepared salt and urea pollutions are sprayed on the insulators and
dried up for sufficiently large time. The process is continued until a
uniform layer is formed on the surface of insulator. For each insulator
rating, four samples were tested. The maximum leakage current and
breakdown voltage were measured. From experimental data,
performance of test specimen is evaluated by comparing breakdown
voltage and leakage current during different seasons when exposed to
salt and urea polluted conditions. From these results the performance
of the insulators can be predicted when they are installed in
industrial, agricultural, and coastal areas. The experimental tests were
carried out in the High Voltage laboratory using two stage cascade
transformer having the rating of 1000 kVA, 500 kV.
Abstract: In this research, we propose to conduct diagnostic and
predictive analysis about the key factors and consequences of urban
population relocation. To achieve this goal, urban simulation models
extract the urban development trends as land use change patterns from
a variety of data sources. The results are treated as part of urban big
data with other information such as population change and economic
conditions. Multiple data mining methods are deployed on this data to
analyze nonlinear relationships between parameters. The result
determines the driving force of population relocation with respect to
urban sprawl and urban sustainability and their related parameters.
This work sets the stage for developing a comprehensive urban
simulation model for catering to specific questions by targeted users. It
contributes towards achieving sustainability as a whole.
Abstract: Objective: Safety and efficacy of Ahmed glaucoma
valve implantation for the management of uveitis induced glaucoma
evaluated on the five dogs with uncontrollable glaucoma. Materials
and Methods: Ahmed Glaucoma Valve (AGV®; New World
Medical, Rancho Cucamonga, CA, USA) is a flow restrictive, nonobstructive
self-regulating valve system. Preoperative ocular
evaluation included direct ophthalmoscopy and measurement of the
intraocular pressure (IOP). The implant was examined and primed
prior to implantation. The selected site of the valve implantation was
the superior quadrant between the superior and lateral rectus muscles.
A fornix-based incision was made through the conjunectiva and
Tenon’s capsule. A pocket is formed by blunt dissection of Tenon’s
capsule from the episclera. The body of the implant was inserted into
the pocket with the leading edge of the device around 8-10 mm from
the limbus. Results: No post-operative complications were detected
in the operated eyes except a persistent corneal edema occupied the
upper half of the cornea in one case. Hyphaema was very mild and
seen only in two cases which resolved quickly two days after surgery.
Endoscopical evaluation for the operated eyes revealed a normal
ocular fundus with clearly visible optic papilla, tapetum and retinal
blood vessels. No evidence of hemorrhage, infection, adhesions or
retinal abnormalities was detected. Conclusion: Ahmed glaucoma
valve is safe and effective implant for treatment of uveitic glaucoma
in dogs.
Abstract: Segmentation of left ventricle (LV) from cardiac
ultrasound images provides a quantitative functional analysis of the
heart to diagnose disease. Active Shape Model (ASM) is widely used
for LV segmentation, but it suffers from the drawback that
initialization of the shape model is not sufficiently close to the target,
especially when dealing with abnormal shapes in disease. In this work,
a two-step framework is improved to achieve a fast and efficient LV
segmentation. First, a robust and efficient detection based on Hough
forest localizes cardiac feature points. Such feature points are used to
predict the initial fitting of the LV shape model. Second, ASM is
applied to further fit the LV shape model to the cardiac ultrasound
image. With the robust initialization, ASM is able to achieve more
accurate segmentation. The performance of the proposed method is
evaluated on a dataset of 810 cardiac ultrasound images that are mostly
abnormal shapes. This proposed method is compared with several
combinations of ASM and existing initialization methods. Our
experiment results demonstrate that accuracy of the proposed method
for feature point detection for initialization was 40% higher than the
existing methods. Moreover, the proposed method significantly
reduces the number of necessary ASM fitting loops and thus speeds up
the whole segmentation process. Therefore, the proposed method is
able to achieve more accurate and efficient segmentation results and is
applicable to unusual shapes of heart with cardiac diseases, such as left
atrial enlargement.
Abstract: Journal bearings used in IC engines are prone to premature
failures and are likely to fail earlier than the rated life due to
highly impulsive and unstable operating conditions and frequent
starts/stops. Vibration signature extraction and wear debris analysis
techniques are prevalent in industry for condition monitoring of
rotary machinery. However, both techniques involve a great deal of
technical expertise, time, and cost. Limited literature is available on
the application of these techniques for fault detection in reciprocating
machinery, due to the complex nature of impact forces that
confounds the extraction of fault signals for vibration-based analysis
and wear prediction. In present study, a simulation model was developed to investigate
the bearing wear behaviour, resulting because of different operating
conditions, to complement the vibration analysis. In current
simulation, the dynamics of the engine was established first, based on
which the hydrodynamic journal bearing forces were evaluated by
numerical solution of the Reynold’s equation. In addition, the
essential outputs of interest in this study, critical to determine wear
rates are the tangential velocity and oil film thickness between the
journals and bearing sleeve, which if not maintained appropriately,
have a detrimental effect on the bearing performance. Archard’s wear prediction model was used in the simulation to
calculate the wear rate of bearings with specific location information
as all determinative parameters were obtained with reference to crank
rotation. Oil film thickness obtained from the model was used as a
criterion to determine if the lubrication is sufficient to prevent contact
between the journal and bearing thus causing accelerated wear. A
limiting value of 1 μm was used as the minimum oil film thickness
needed to prevent contact. The increased wear rate with growing
severity of operating conditions is analogous and comparable to the
rise in amplitude of the squared envelope of the referenced vibration
signals. Thus on one hand, the developed model demonstrated its
capability to explain wear behaviour and on the other hand it also
helps to establish a co-relation between wear based and vibration
based analysis. Therefore, the model provides a cost effective and
quick approach to predict the impending wear in IC engine bearings
under various operating conditions.
Abstract: Searching the “Island of stability” is a topic of
extreme interest in theoretical as well as experimental modern
physics today. This “island of stability” is spanned by superheavy
elements (SHE's) that are produced in the laboratory. SHE's are
believed to exist primarily due to the “magic” stabilizing effects of
nuclear shell structure. SHE synthesis is extremely difficult due to
their very low production cross section, often of the order of pico
barns or less. Stabilizing effects of shell closures at proton number
Z=82 and neutron number N=126 are predicted theoretically. Though
stabilizing effects of Z=82 have been experimentally verified, no
concluding observations have been made with N=126, so far. We
measured and analyzed the total evaporation residue (ER) cross
sections for a number of systems with neutron number around 126 to
explore possible shell closure effects in ER cross sections, in this
work.
Abstract: This experimental study consists of a characterization
of epoxy grout where an amount of 2% of graphene nanoplatelets
particles were added to commercial epoxy resin to evaluate their
behavior regarding neat epoxy resin. Compressive tests, tensile tests
and flexural tests were conducted to study the effect of graphene
nanoplatelets on neat epoxy resin. By comparing graphene-based and
neat epoxy grout, there is no significant increase of strength due to
weak interface in the graphene nanoplatelets/epoxy composites.
From this experiment, the tension and flexural strength of graphenebased
epoxy grouts is slightly lower than ones of neat epoxy grout.
Nevertheless, the addition of graphene has produced more consistent
results according to a smaller standard deviation of strength.
Furthermore, the graphene has also improved the ductility of the
grout, hence reducing its brittle behaviour. This shows that the
performance of graphene-based grout is reliably predictable and able
to minimise sudden rupture. This is important since repair design of
damaged pipeline is of deterministic nature.