Abstract: An Energetic and exergetic analysis is conducted on a
Steam Turbine Power Plant of an existing Phosphoric Acid Factory.
The heat recovery systems used in different parts of the plant are also
considered in the analysis. Mass, thermal and exergy balances are
established on the main compounds of the factory. A numerical code
is established using EES software to perform the calculations
required for the thermal and exergy plant analysis. The effects of the
key operating parameters such as steam pressure and temperature,
mass flow rate as well as seawater temperature, on the cycle
performances are investigated. A maximum Exergy Loss Rate of about 72% is obtained for the
melters, followed by the condensers, heat exchangers and the pumps.
The heat exchangers used in the phosphoric acid unit present
exergetic efficiencies around 33% while 60% to 72% are obtained for
steam turbines and blower. For the explored ranges of HP steam
temperature and pressure, the exergy efficiencies of steam turbine
generators STGI and STGII increase of about 2.5% and 5.4%
respectively. In the same way optimum HP steam flow rate values,
leading to the maximum exergy efficiencies are defined.
Abstract: Excessive vibration means increased wear, increased
repair efforts, bad product selection & quality and high energy
consumption. This may be sometimes experienced by cavitation or
suction/discharge recirculation which could occur only when net
positive suction head available NPSHA drops below the net positive
suction head required NPSHR. Cavitation can cause axial surging, if it
is excessive, will damage mechanical seals, bearings, possibly other
pump components frequently, and shorten the life of the impeller.
Efforts have been made to explain Suction Energy (SE), Specific
Speed (Ns), Suction Specific Speed (Nss), NPSHA, NPSHR & their
significance, possible reasons of cavitation /internal recirculation, its
diagnostics and remedial measures to arrest and prevent cavitation in
this paper. A case study is presented by the author highlighting that
the root cause of unwanted noise and vibration is due to cavitation,
caused by high specific speeds or inadequate net- positive suction
head available which results in damages to material surfaces of
impeller & suction bells and degradation of machine performance, its
capacity and efficiency too. Author strongly recommends revisiting
the technical specifications of CW pumps to provide sufficient NPSH
margin ratios >1.5, for future projects and Nss be limited to 8500 -
9000 for cavitation free operation.
Abstract: The occurrences of precipitation, also commonly
referred as rain, in the form of "convective" and "stratiform" have
been identified to exist worldwide. In this study, the radar return
echoes or known as reflectivity values acquired from radar scans
have been exploited in the process of classifying the type of rain
endured. The investigation use radar data from Malaysian
Meteorology Department (MMD). It is possible to discriminate the
types of rain experienced in tropical region by observing the vertical
characteristics of the rain structure. .Heavy rain in tropical region
profoundly affects radiowave signals, causing transmission
interference and signal fading. Required wireless system fade margin
depends on the type of rain. Information relating to the two
mentioned types of rain is critical for the system engineers and
researchers in their endeavour to improve the reliability of
communication links. This paper highlights the quantification of
percentage occurrences over one year period in 2009.
Abstract: This paper focuses on the study of DC-to-DC
converters, which are suitable for low-voltage high-power
applications. The output voltages generated by renewable energy
sources such as photovoltaic arrays and fuel cell stacks are
generally low and required to be increased to high voltage levels.
Development of DC-to-DC converters, which provide high step-up
voltage conversion ratios with high efficiencies and low voltage
stresses, is one of the main issues in the development of renewable
energy systems. A procedure for three converters−conventional
DC-to-DC converter, interleaved boost converter, and isolated flyback
based converter, is illustrated for a given set of specifications. The
selection among the converters for the given application is based on
the voltage conversion ratio, efficiency, and voltage stresses.
Abstract: Companies face increasing challenges in research due
to higher costs and risks. The intensifying technology complexity and
interdisciplinarity require unique know-how. Therefore, companies
need to decide whether research shall be conducted internally or
externally with partners. On the other hand, research institutes meet
increasing efforts to achieve good financing and to maintain high
research reputation. Therefore, relevant research topics need to be
identified and specialization of competency is necessary. However,
additional competences for solving interdisciplinary research projects
are also often required. Secured financing can be achieved by
bonding industry partners as well as public fundings. The realization
of faster and better research drives companies and research institutes
to cooperate in organized research networks, which are managed by
an administrative organization. For an effective and efficient
cooperation, necessary processes, roles, tools and a set of rules need
to be determined. Goal of this paper is to show the state-of-art
research and to propose a governance framework for organized
research networks.
Abstract: Web Usage Mining is the application of data mining
techniques to find usage patterns from web log data, so as to grasp
required patterns and serve the requirements of Web-based
applications. User’s expertise on the internet may be improved by
minimizing user’s web access latency. This may be done by
predicting the future search page earlier and the same may be prefetched
and cached. Therefore, to enhance the standard of web
services, it is needed topic to research the user web navigation
behavior. Analysis of user’s web navigation behavior is achieved
through modeling web navigation history. We propose this technique
which cluster’s the user sessions, based on the K-medoids technique.
Abstract: Average temperatures worldwide are expected to
continue to rise. At the same time, major cities in developing
countries are becoming increasingly populated and polluted.
Governments are tasked with the problem of overheating and air
quality in residential buildings. This paper presents the development
of a model, which is able to estimate the occupant exposure
to extreme temperatures and high air pollution within domestic
buildings. Building physics simulations were performed using the
EnergyPlus building physics software. An accurate metamodel is
then formed by randomly sampling building input parameters and
training on the outputs of EnergyPlus simulations. Metamodels are
used to vastly reduce the amount of computation time required when
performing optimisation and sensitivity analyses. Neural Networks
(NNs) have been compared to a Radial Basis Function (RBF)
algorithm when forming a metamodel. These techniques were
implemented using the PyBrain and scikit-learn python libraries,
respectively. NNs are shown to perform around 15% better than RBFs
when estimating overheating and air pollution metrics modelled by
EnergyPlus.
Abstract: This paper aimed to introduce the solution of concrete
slump recovery using chemical admixture type-F (superplasticizer,
naphthalene base) to the practice in order to solve unusable concrete
problem due to concrete loss its slump, especially for those tropical
countries that have faster slump loss rate. In the other hand, randomly
adding superplasticizer into concrete can cause concrete to segregate.
Therefore, this paper also develops the estimation model used to
calculate amount of second dose of superplasticizer need for concrete
slump recovery. Fresh properties of ordinary Portland cement
concrete with volumetric ratio of paste to void between aggregate
(paste content) of 1.1-1.3 with water-cement ratio zone of 0.30 to
0.67 and initial superplasticizer (naphthalene base) of 0.25%-1.6%
were tested for initial slump and slump loss for every 30 minutes for
one and half hour by slump cone test. Those concretes with slump
loss range from 10% to 90% were re-dosed and successfully
recovered back to its initial slump. Slump after re-dosed was tested
by slump cone test. From the result, it has been concluded that, slump
loss was slower for those mix with high initial dose of
superplasticizer due to addition of superplasticizer will disturb
cement hydration. The required second dose of superplasticizer was
affected by two major parameters, which were water-cement ratio
and paste content, where lower water-cement ratio and paste content
cause an increase in require second dose of superplasticizer. The
amount of second dose of superplasticizer is higher as the solid
content within the system is increase, solid can be either from cement
particles or aggregate. The data was analyzed to form an equation use
to estimate the amount of second dosage requirement of
superplasticizer to recovery slump to its original.
Abstract: Response Surface Methods (RSM) provide
statistically validated predictive models that can then be manipulated
for finding optimal process configurations. Variation transmitted to
responses from poorly controlled process factors can be accounted
for by the mathematical technique of propagation of error (POE),
which facilitates ‘finding the flats’ on the surfaces generated by
RSM. The dual response approach to RSM captures the standard
deviation of the output as well as the average. It accounts for
unknown sources of variation. Dual response plus propagation of
error (POE) provides a more useful model of overall response
variation. In our case, we implemented this technique in predicting
compressive strength of concrete of 28 days in age. Since 28 days is
quite time consuming, while it is important to ensure the quality
control process. This paper investigates the potential of using design
of experiments (DOE-RSM) to predict the compressive strength of
concrete at 28th day. Data used for this study was carried out from
experiment schemes at university of Benghazi, civil engineering
department. A total of 114 sets of data were implemented. ACI mix
design method was utilized for the mix design. No admixtures were
used, only the main concrete mix constituents such as cement, coarseaggregate,
fine aggregate and water were utilized in all mixes.
Different mix proportions of the ingredients and different water
cement ratio were used. The proposed mathematical models are
capable of predicting the required concrete compressive strength of
concrete from early ages.
Abstract: Laura Island, which is located about 50 km away from
downtown, is a source of water supply in Majuro atoll, which is the
capital of the Republic of the Marshall Islands. Low and flat Majuro
atoll has neither river nor lake. It is very important for Majuro atoll to
ensure the conservation of its water resources. However, upconing,
which is the process of partial rising of the freshwater-saltwater
boundary near the water-supply well, was caused by the excess
pumping from it during the severe drought in 1998. Upconing will
make the water usage of the freshwater lens difficult. Thus,
appropriate water usage is required to prevent up coning in the
freshwater lens because there is no other water source during drought. Numerical simulation of water usage applying SEAWAT model
was conducted at the central part of Laura Island, including the water
supply well, which was affected by upconing. The freshwater lens was
created as a result of infiltration of consistent average rainfall. The lens
shape was almost the same as the one in 1985. 0 of monthly rainfall
and variable daily pump discharge were used to calculate the
sustainable pump discharge from the water supply well. Consequently,
the total amount of pump discharge was increased as the daily pump
discharge was increased, indicating that it needs more time to recover
from upconing. Thus, a pump standard to reduce the pump intensity is
being proposed, which is based on numerical simulation concerning
the occurrence of the up-coning phenomenon in Laura Island during
the drought.
Abstract: Financial literacy is a widely discussed topic on the
national and international level by governments, organizations and
academia. For this reason, this study analyses financial knowledge,
financial behavior, and financial attitudes of students of finance. The
aim of the paper is to determine whether the financial literacy of
university students studying finance differs from the level of financial
literacy in selected OECD countries. The research was conducted at
Masaryk University in the Czech Republic. The empirical study
comprises questions related to several aspects of financial literacy,
such as financial knowledge, personal finance behavior, or decisionmaking.
The results indicate that improvement in financial literacy of
university students is still required, even though their major is finance
related.
Abstract: Gladiolus is an important cash crop and is grown
mainly for its elegant spikes. Traditionally the gladiolus corms are
planted manually which is very tedious, time consuming and labor
intensive operation. So far, there is no planter available for planting
of gladiolus corms. With a view to mechanize the planting operation
of this horticultural crop, a prototype of 4-row gladiolus planter was
developed and its performance was evaluated in-situ condition. Cupchain
type metering device was used to place each single gladiolus
corm in furrow at required spacing while planting. Three levels of
corm spacing viz 15, 20 and 25 cm and four levels of forward speed
viz 1.0, 1.5, 2.0 and 2.5 km/h was taken as evaluation parameter for
the planter. The performance indicators namely corm spacing in each
row, coefficient of uniformity, missing index, multiple index, quality
of feed index, number of corms per meter length, mechanical damage
to the corms etc. were determined during the field test. The data was
statistically analyzed using Completely Randomized Design (CRD)
for testing the significance of the parameters. The result indicated
that planter was able to drop the corms at required nominal spacing
with minor variations. The highest deviation from the mean corm
spacing was observed as 3.53 cm with maximum coefficient of
variation as 13.88%. The highest missing and quality of feed indexes
were observed as 6.33% and 97.45% respectively with no multiples.
The performance of the planter was observed better at lower forward
speed and wider corm spacing. The field capacity of the planter was
found as 0.103 ha/h with an observed field efficiency of 76.57%.
Abstract: The power electronic components within Electric Vehicles (EV) need to operate in several important modes. Some modes directly influence safety, while others influence vehicle performance. Given the variety of functions and operational modes required of the power electronics, it needs to meet efficiency requirements to minimize power losses. Another challenge in the control and construction of such systems is the ability to support bidirectional power flow. This paper considers the construction, operation, and feasibility of available converters for electric vehicles with feasible configurations of electrical buses and loads. This paper describes logic and control signals for the converters for different operations conditions based on the efficiency and energy usage bases.
Abstract: Considering the challenges of short product life cycles
and growing variant diversity, cost minimization and manufacturing
flexibility increasingly gain importance to maintain a competitive
edge in today’s global and dynamic markets. In this context, an
aerodynamic part feeding system for high-speed industrial assembly
applications has been developed at the Institute of Production
Systems and Logistics (IFA), Leibniz Universitaet Hannover. The
aerodynamic part feeding system outperforms conventional systems
with respect to its process safety, reliability, and operating speed. In
this paper, a multi-objective optimisation of the aerodynamic feeding
system regarding the orientation rate, the feeding velocity, and the
required nozzle pressure is presented.
Abstract: This research work presents the surface
thermodynamics approach to M-TB/HIV-Human sputum
interactions. This involved the use of the Hamaker coefficient
concept as a surface energetics tool in determining the interaction
processes, with the surface interfacial energies explained using van
der Waals concept of particle interactions. The Lifshitz derivation for
van der Waals forces was applied as an alternative to the contact
angle approach which has been widely used in other biological
systems. The methodology involved taking sputum samples from
twenty infected persons and from twenty uninfected persons for
absorbance measurement using a digital Ultraviolet visible
Spectrophotometer. The variables required for the computations with
the Lifshitz formula were derived from the absorbance data. The
Matlab software tools were used in the mathematical analysis of the
data produced from the experiments (absorbance values). The
Hamaker constants and the combined Hamaker coefficients were
obtained using the values of the dielectric constant together with the
Lifshitz Equation. The absolute combined Hamaker coefficients
A132abs and A131abs on both infected and uninfected sputum samples
gave the values of A132abs = 0.21631x10-21Joule for M-TB infected
sputum and Ã132abs = 0.18825x10-21Joule for M-TB/HIV infected
sputum. The significance of this result is the positive value of the
absolute combined Hamaker coefficient which suggests the existence
of net positive van der waals forces demonstrating an attraction
between the bacteria and the macrophage. This however, implies that
infection can occur. It was also shown that in the presence of HIV,
the interaction energy is reduced by 13% conforming adverse effects
observed in HIV patients suffering from tuberculosis.
Abstract: The understanding of geotechnical characteristics of
near-surface material and the effects of the groundwater is very
important problem in such as site studies. For showing the relations
between seismic data and groundwater, we selected about 25 km2 as
the study area. It has been presented which is a detailed work of
seismic data and groundwater depths of Gokpinar Damp area.
Seismic waves velocity (Vp and Vs) are very important parameters
showing the soil properties. The seismic records were used the
method of the multichannel analysis of surface waves near area of
Gokpinar Damp area. Sixty sites in this area have been investigated
with survey lines about 60 m in length. MASW (Multichannel
analysis of surface wave) method has been used to generate onedimensional
shear wave velocity profile at locations. These shear
wave velocities are used to estimate equivalent shear wave velocity in
the study area at every 2 and 5 m intervals up to a depth of 45 m.
Levels of equivalent shear wave velocity of soil are used the
classified of the study area. After the results of the study, it must be
considered as components of urban planning and building design of
Gokpinar Damp area, Denizli and the application and use of these
results should be required and enforced by municipal authorities.
Abstract: Within this paper, latest results on processing of energetic nanomaterials by means of the Spray Flash Evaporation technique are presented. This technology constitutes a highly effective and continuous way to prepare fascinating materials on the nano- and micro-scale. Within the process, a solution is set under high pressure and sprayed into an evacuated atomization chamber. Subsequent ultrafast evaporation of the solvent leads to an aerosol stream, which is separated by cyclones or filters. No drying gas is required, so the present technique should not be confused with spray dying. Resulting nanothermites, insensitive explosives or propellants and compositions are foreseen to replace toxic (according to REACH) and very sensitive matter in military and civil applications. Diverse examples are given in detail: nano-RDX (n-Cyclotrimethylentrinitramin) and nano-aluminum based systems, mixtures (n-RDX/n-TNT - trinitrotoluene) or even cocrystalline matter like n-CL-20/HMX (Hexanitrohexaazaisowurtzitane/ Cyclotetra-methylentetranitramin). These nanomaterials show reduced sensitivity by trend without losing effectiveness and performance. An analytical study for material characterization was performed by using Atomic Force Microscopy, X-Ray Diffraction, and combined techniques as well as spectroscopic methods. As a matter of course, sensitivity tests regarding electrostatic discharge, impact, and friction are provided.
Abstract: Lateral Geniculate Nucleus (LGN) is the relay center
in the visual pathway as it receives most of the input information
from retinal ganglion cells (RGC) and sends to visual cortex. Low
threshold calcium currents (IT) at the membrane are the unique
indicator to characterize this firing functionality of the LGN neurons
gained by the RGC input. According to the LGN functional
requirements such as functional mapping of RGC to LGN, the
morphologies of the LGN neurons were developed. During the
neurological disorders like glaucoma, the mapping between RGC and
LGN is disconnected and hence stimulating LGN electrically using
deep brain electrodes can restore the functionalities of LGN. A
computational model was developed for simulating the LGN neurons
with three predominant morphologies each representing different
functional mapping of RGC to LGN. The firings of action potentials
at LGN neuron due to IT were characterized by varying the
stimulation parameters, morphological parameters and orientation. A
wide range of stimulation parameters (stimulus amplitude, duration
and frequency) represents the various strengths of the electrical
stimulation with different morphological parameters (soma size,
dendrites size and structure). The orientation (0-1800) of LGN
neuron with respect to the stimulating electrode represents the angle
at which the extracellular deep brain stimulation towards LGN
neuron is performed. A reduced dendrite structure was used in the
model using Bush–Sejnowski algorithm to decrease the
computational time while conserving its input resistance and total
surface area. The major finding is that an input potential of 0.4 V is
required to produce the action potential in the LGN neuron which is
placed at 100 μm distance from the electrode. From this study, it can
be concluded that the neuroprostheses under design would need to
consider the capability of inducing at least 0.4V to produce action
potentials in LGN.
Abstract: The current statuses of lifetime test of LaB6 hollow
cathode at the Lanzhou Institute of Physics (LIP), China, was
described. 5A LaB6 hollow cathode was design for LIPS-200 40mN
Xenon ion thruster, and it could be used for LHT-100 80 mN Hall
thruster, too. Life test of the discharge and neutralizer modes of LHC-5
hollow cathode were stared in October 2011, and cumulative operation
time reached 17,300 and 16,100 hours in April 2015, respectively. The
life of cathode was designed more than 11,000 hours. Parameters of
discharge and key structure dimensions were monitored in different
stage of life test indicated that cathodes were health enough. The test
will continue until the cathode cannot work or operation parameter is
not in normally. The result of the endurance test of cathode
demonstrated that the LaB6 hollow cathode is satisfied for the required
of thruster in life and performance.
Abstract: Foundation differential settlement and supported
structure tilting are an occasionally occurred engineering problem.
This may be caused by overloading, changes in ground soil properties
or unsupported nearby excavations. Engineering thinking points
directly toward the logic solution for such problem by uplifting the
settled side. This can be achieved with deep foundation elements
such as micro-piles and macro-piles™, jacked piers, and helical piers,
jet grouted mortar columns, compaction grout columns, cement
grouting or with chemical grouting, or traditional pit underpinning
with concrete and mortar. Although, some of these techniques offer
economic, fast and low noise solutions, many of them are quite the
contrary. For tilted structures, with the limited inclination, it may be much
easier to cause a balancing settlement on the less-settlement side
which shall be done carefully in a proper rate. This principal has been
applied in Leaning Tower of Pisa stabilization with soil extraction
from the ground surface. In this research, the authors attempt to
introduce a new solution with a different point of view. So, the
micro-tunneling technique is presented in here as an intended ground
deformation cause. In general, micro-tunneling is expected to induce
limited ground deformations. Thus, the researchers propose to apply
the technique to form small size ground unsupported holes to produce
the target deformations. This shall be done in four phases: 1.
Application of one or more micro-tunnels, regarding the existing
differential settlement value, under the raised side of the tilted
structure. 2. For each individual tunnel, the lining shall be pulled out
from both sides (from jacking and receiving shafts) in the slow rate.
3. If required, according to calculations and site records, an additional
surface load can be applied on the raised foundation side. 4. Finally, a
strengthening soil grouting shall be applied for stabilization after
adjustment. A finite element based numerical model is presented to simulate
the proposed construction phases for different tunneling positions and
tunnels group. For each case, the surface settlements are calculated
and induced plasticity points are checked. These results show the
impact of the suggested procedure on the tilted structure and its
feasibility. Comparing results also show the importance of the
position selection and tunnels group gradual effect. Thus, a new
engineering solution is presented to one of the structural and
geotechnical engineering challenges.