Abstract: Vibration characteristics of subcooled flow boiling on
thin and long structures such as a heating rod were recently
investigated by the author. The results show that the intensity of the
subcooled boiling-induced vibration (SBIV) was influenced strongly
by the conditions of the subcooling temperature, linear power density
and flow velocity. Implosive bubble formation and collapse are the
main nature of subcooled boiling, and their behaviors are the only
sources to originate from SBIV. Therefore, in order to explain the
phenomenon of SBIV, it is essential to obtain reliable information
about bubble behavior in subcooled boiling conditions. This was
investigated at different conditions of coolant subcooling
temperatures of 25 to 75°C, coolant flow velocities of 0.16 to
0.53m/s, and linear power densities of 100 to 600 W/cm. High speed
photography at 13,500 frames per second was performed at these
conditions. The results show that even at the highest subcooling
condition, the absolute majority of bubbles collapse very close to the
surface after detaching from the heating surface. Based on these
observations, a simple model of surface tension and momentum
change is introduced to offer a rough quantitative estimate of the
force exerted on the heating surface during the bubble ebullition. The
formation of a typical bubble in subcooled boiling is predicted to
exert an excitation force in the order of 10-4 N.
Abstract: This paper presents an experimental investigation using Acoustic Emission (AE) technology to monitor sand transportation in multiphase flow. The investigations were undertaken on three-phase (air-water-sand) flow in a horizontal pipe where the superficial gas velocity (VSG) had a range of between 0.2msˉ¹ to 2.0msˉ¹ and superficial liquid velocity (VSL) had a range of between 0.2msˉ¹ to 1.0msˉ¹. The experimental findings clearly show a correlation exists between AE energy levels, sand concentration, superficial gas velocity (VSG), and superficial liquid velocity (VSL).
Abstract: Nanofluids are novel fluids that are going to have an
important role in future industrial thermal device designs. Studies are
being predominantly conducted on the mechanism of these heat
transfers. The key to this attraction is in the increase in thermal
conductivity brought about by the Nanofluids compared with the
base fluid. Different models have been proposed for calculation of
effective thermal conduction that has been gradually modified. In this
investigation effect of nanolayer structure and Brownian motion of
particles are studied and a new modified thermal conductivity model
is proposed. Temperature, concentration, nanolayer thickness and
particle size are taken as variables and their effect are studied
simultaneously on the thermal conductivity of the fluids, showing the
concentration of the nanoparticles to affect the nanolayer thickness
which also affects the Brownian motion.
Abstract: With the explosive growth of data available on the
Internet, personalization of this information space become a
necessity. At present time with the rapid increasing popularity of the
WWW, Websites are playing a crucial role to convey knowledge and
information to the end users. Discovering hidden and meaningful
information about Web users usage patterns is critical to determine
effective marketing strategies to optimize the Web server usage for
accommodating future growth. The task of mining useful information
becomes more challenging when the Web traffic volume is enormous
and keeps on growing. In this paper, we propose a intelligent model
to discover and analyze useful knowledge from the available Web
log data.
Abstract: The evaluation of conversational agents or chatterbots question answering systems is a major research area that needs much attention. Before the rise of domain-oriented conversational agents based on natural language understanding and reasoning, evaluation is never a problem as information retrieval-based metrics are readily available for use. However, when chatterbots began to become more domain specific, evaluation becomes a real issue. This is especially true when understanding and reasoning is required to cater for a wider variety of questions and at the same time to achieve high quality responses. This paper discusses the inappropriateness of the existing measures for response quality evaluation and the call for new standard measures and related considerations are brought forward. As a short-term solution for evaluating response quality of conversational agents, and to demonstrate the challenges in evaluating systems of different nature, this research proposes a blackbox approach using observation, classification scheme and a scoring mechanism to assess and rank three example systems, AnswerBus, START and AINI.
Abstract: Beginning from the creator of integro-differential
equations Volterra, many scientists have investigated these
equations. Classic method for solving integro-differential
equations is the quadratures method that is successfully applied up
today. Unlike these methods, Makroglou applied hybrid methods
that are modified and generalized in this paper and applied to the
numerical solution of Volterra integro-differential equations. The
way for defining the coefficients of the suggested method is also
given.
Abstract: This study investigated the effect of oxygen and
micro-cracking on the flotation of low grade nickel sulphide ore. The
ore treated contained serpentine minerals which have a history of
being difficult to process efficiently. The use of oxygen as a bubbling
gas has been noted to be effective because it increases the pulp
potential. The desired effect of micro cracking the ore is that the
nickel sulphide minerals will become activated and this activation
will render these minerals more susceptible to react with potassium
amyl xanthate collectors, resulting in a higher recovery of nickel and
hinder the recovery of other undesired minerals contained in the ore.
Higher nickel recoveries were obtained when pure oxygen was used
as a bubbling gas rather than the conventional air. Microwave
cracking favored the recovery of nickel.
Abstract: Intelligent systems are required in order to quickly and accurately analyze enormous quantities of data in the Internet environment. In intelligent systems, information extracting processes can be divided into supervised learning and unsupervised learning. This paper investigates intelligent clustering by unsupervised learning. Intelligent clustering is the clustering system which determines the clustering model for data analysis and evaluates results by itself. This system can make a clustering model more rapidly, objectively and accurately than an analyzer. The methodology for the automatic clustering intelligent system is a multi-agent system that comprises a clustering agent and a cluster performance evaluation agent. An agent exchanges information about clusters with another agent and the system determines the optimal cluster number through this information. Experiments using data sets in the UCI Machine Repository are performed in order to prove the validity of the system.
Abstract: Boron minerals are very useful for various industrial
activities, such as glass industry and detergent industry, due to its
mechanical and chemical properties. During the production of boron
compounds, many of these are introduced into the environment in the
form of waste. Boron is also an important micro nutrient for the
plants to vegetate but if it exists in high concentrations, it could have
toxic effects. The maximum boron level in drinking water for human
health is given as 0.3 mg/L in World Health Organization (WHO)
standards. The toxic effects of boron should be noted especially for
dry regions, thus, in recent years, increasing attention has been paid
to remove the boron from waste waters. In this study, boron removal
is implemented by ion exchange process using Amberlite IRA-743
resin. Amberlite IRA-743 resin is a boron specific resin and it
belongs to the polymerizate sorbent group within the aminopolyol
functional group. Batch studies were performed to investigate the
effects of various experimental parameters, such as adsorbent dose,
initial concentration and pH, on the removal of boron. It is found
that, when the adsorbent dose increases removal of boron from the
liquid phase increases. However, an increase in the initial
concentration decreases the removal of boron. The effective pH
values for removal of boron are determined between 8.5 and 9.
Equilibrium isotherms were also analyzed by Langmuir and
Freundlich isotherm models. The Langmuir isotherm is obeyed better
than the Freundlich isotherm.
Abstract: The supported Pd catalysts were analyzed by X-ray
diffraction and X-ray absorption spectroscopy in order to determine
their global and local structure. The average particle size of the
supported Pd catalysts was determined by X-ray diffraction method.
One of the main purposes of the present contribution is to focus on
understanding the specific role of the Pd particle size determined by
X-ray diffraction and that of the support oxide. Based on X-ray
absorption fine structure spectroscopy analysis we consider that the
whole local structure of the investigated samples are distorted
concerning the atomic number but the distances between atoms are
almost the same as for standard Pd sample. Due to the strong
modifications of the Pd cluster local structure, the metal-support
interface may influence the electronic properties of metal clusters
and thus their reactivity for absorption of the reactant molecules.
Abstract: This study investigated the removal efficiency of electrokinetic remediation of copper-contaminated soil at different combinations of enhancement reagents used as anolyte and catholyte. Sodium hydroxide (at 0.1, 0.5, and 1.0 M concentrations) and distilled water were used as anolyte, while lactic acid (at 0.01, 0.1, and 0.5 M concentrations), ammonium citrate (also at 0.01, 0.1, and 0.5 M concentrations) and distilled water were used as catholyte. A continuous voltage application (1.0 VDC/cm) was employed for 240 hours for each experiment. The copper content of the catholyte was determined at the end of the 240-hour period. Optimization was carried out with a Response Surface Methodology - Optimal Design, including F test, and multiple comparison method, to determine which pair of anolyte-catholyte was the most significant for the removal efficiency. "1.0 M NaOH" was found to be the most significant anolyte while it was established that lactic acid was the most significant type of catholyte to be used for the most successful electrokinetic experiments. Concentrations of lactic acid should be at the range of 0.1 M to 0.5 M to achieve maximum percent removal values.
Abstract: In the process of polyethylene extrusion polymer
material similar to powder or granule is under compression, melting
and transmission operation and on base of special form, extrudate has
been produced. Twin-screw extruders are applicable in industries
because of their high capacity. The powder mixing with chemical
additives and melting with thermal and mechanical energy in three
zones (feed, compression and metering zone) and because of gear
pump and screw's pressure, converting to final product in latest plate.
Extruders with twin-screw and short distance between screws are
better than other types because of their high capacity and good
thermal and mechanical stress.
In this paper, process of polyethylene extrusion and various tapes
of extruders are studied. It is necessary to have an exact control on
process to producing high quality products with safe operation and
optimum energy consumption.
The granule size is depending on granulator motor speed. Results
show at constant feed rate a decrease in granule size was found whit
Increase in motor speed. Relationships between HDPE feed rate and
speed of granulator motor, main motor and gear pump are calculated
following as:
x = HDPE feed flow rate, yM = Main motor speed
yM = (-3.6076e-3) x^4+ (0.24597) x^3+ (-5.49003) x^2+ (64.22092)
x+61.66786 (1)
x = HDPE feed flow rate, yG = Gear pump speed
yG = (-2.4996e-3) x^4+ (0.18018) x^3+ (-4.22794) x^2+ (48.45536)
x+18.78880 (2)
x = HDPE feed flow rate, y = Granulator motor speed
10th Degree Polynomial Fit: y = a+bx+cx^2+dx^3... (3)
a = 1.2751, b = 282.4655, c = -165.2098,
d = 48.3106, e = -8.18715, f = 0.84997
g = -0.056094, h = 0.002358, i = -6.11816e-5
j = 8.919726e-7, k = -5.59050e-9
Abstract: This paper presents the results related to the
interference reduction technique in multistage multiuser detector for
asynchronous DS-CDMA system. To meet the real-time
requirements for asynchronous multiuser detection, a bit streaming,
cascade architecture is used. An asynchronous multiuser detection
involves block-based computations and matrix inversions. The paper
covers iterative-based suboptimal schemes that have been studied to
decrease the computational complexity, eliminate the need for matrix
inversions, decreases the execution time, reduces the memory
requirements and uses joint estimation and detection process that
gives better performance than the independent parameter estimation
method. The stages of the iteration use cascaded and bits processed
in a streaming fashion. The simulation has been carried out for
asynchronous DS-CDMA system by varying one parameter, i.e.,
number of users. The simulation result exhibits that system gives
optimum bit error rate (BER) at 3rd stage for 15-users.
Abstract: In countries with hot climates, air-conditioning forms
a large proportion of annual peak electrical demand, requiring
expansion of power plants to meet the peak demand, which goes
unused most of the time. Use of well-designed cool storage can offset
the peak demand to a large extent. In this study, an air conditioning
system with naturally stratified storage tank was designed,
constructed and tested. A new type of diffuser was designed and used
in this study. Factors that influence the performance of chilled water
storage tanks were investigated. The results indicated that stratified
storage tank consistently stratified well without any physical barrier.
Investigation also showed that storage efficiency decreased with
increasing flow rate due to increased mixing of warm and chilled
water. Diffuser design and layout primarily affected the mixing near
the inlet diffuser and the extent of this mixing had primary influence
on the shape of the thermocline. The heat conduction through tank
walls and through the thermocline caused widening of mixed volume.
Thermal efficiency of stratified storage tanks was as high as 90
percent, which indicates that stratified tanks can effectively be used
as a load management technique.
Abstract: Due to the low heavy metal concentrations, the
bottom ash from a 32 MW municipal district heating plant was
determined to be a potential forest fertilizer as such. However,
additional Ca would be needed, because its Ca concentration of 1.9-
% (d.w.) was lower than the statutory Finnish minimum limit value
of 6.0-% (d.w.) for Ca in forest fertilizer. Due to the elevated As
concentration (53.0 mg/kg; d.w.) in the fly ash from the 32 MW
municipal district heating plant, and Cr concentration (620 mg/kg;
d.w.) in the ash fraction (i.e. mixture of the bottom ash and fly ash)
from the 6 MW municipal district heating plant, which exceed the
limit values of 30 mg/kg (d.w.) and 300 mg/kg (d.w.) for As and Cr,
respectively, these residues are not suitable as forest fertilizers.
Although these ash fractions cannot be used as a forest fertilizer as
such, they can be used for the landscaping of landfills or in industrial
and other areas that are closed to the public. However, an
environmental permit is then needed.
Abstract: This paper presents and discusses the numerical simulations of transient laminar natural convection cooling of high Prandtl number fluids in cubical cavities, in which the six walls of the cavity are subjected to a step change in temperature. The effect of the fluid Prandtl number on the heat transfer coefficient is studied for three different fluids (Golden Syrup, Glycerin and Glycerin-water solution 50%). The simulations are performed at two different Rayleigh numbers (5·106 and 5·107) and six different Prandtl numbers (3 · 105 ≥Pr≥ 50). Heat conduction through the cavity glass walls is also considered. The propsed correlations of the averaged heat transfer coefficient (N u) showed that it is dependant on the initial Ra and almost independent on P r. The instantaneous flow patterns, temperature contours and time evolution of volume averaged temperature and heat transfer coefficient are presented and analyzed.
Abstract: In this paper, by introducing twice continuously differentiable mappings, we develop an interior path following following method, which enables us to give a constructive proof of the general Brouwer fixed point theorem and thus to solve fixed point problems in a class of non-convex sets. Under suitable conditions, a smooth path can be proven to exist. This can lead to an implementable globally convergent algorithm. Several numerical examples are given to illustrate the results of this paper.
Abstract: This paper describes the design and modeling
procedure of a novel 5-phase segment type switched reluctance motor
(ST-SRM) under simultaneous two-phase (bipolar) excitation of
windings. The rotor cores of ST-SRM are embedded in an aluminum
block as well as to improve the performance characteristics. The
magnetic circuit of the produced ST-SRM is constructed so that the
magnetic flux paths are short and exclusive to each phase, thereby
minimizing the commutation switching and eddy current losses in the
laminations. The design and simulation principles presented apply
primarily to conventional SRM and ST-SRM. It is proved that the
novel 5-phase switched reluctance motor under two-phase excitation
is superior among the criteria used in comparison. The purposed
model is particularly well suited for high torque and weight
constrained applications such as automobiles, aerospace and military
applications.
Abstract: This paper draws a methodological framework adopted within an internal Telecomitalia project aimed to identify, on a user centred base, the potential interest towards a technological scenario aimed to extend on a personal bubble the typical communication and media fruition home environment. The problem is that involving user in the early stage of the development of such disruptive technology scenario asking users opinions on something that users actually do not manage even in a rough manner could lead to wrong or distorted results. For that reason we chose an approach that indirectly aim to understand users hidden needs in order to obtain a meaningful picture of the possible interest for a technological proposition non yet easily understandable.
Abstract: The purpose of this paper is to discuss the influence of
resistance characteristic on the high conductive concrete considering
the various voltage and environment. The four-electrode method is
applied to the tailor-made high conductive concrete with appropriate
proportion. The curve of resistivity with the changes of voltage and
environment is plotted and the changes of resistivity are explored. The
result based on the methods reveals that resistivity is less affected by
the temperature factor, and the four-electrode method would be an
applicable measurement method on a site inspection.