Abstract: This paper presents the exergy analysis of a
desalination unit using humidification-dehumidification process.
Here, this unit is considered as a thermal system with three main
components, which are the heating unit by using a solar collector, the
evaporator or the humidifier, and the condenser or the dehumidifier.
In these components the exergy is a measure of the quality or grade
of energy and it can be destroyed in them. According to the second
law of thermodynamics this destroyed part is due to irreversibilities
which must be determined to obtain the exergetic efficiency of the
system.
In the current paper a computer program has been developed using
visual basic to determine the exergy destruction and the exergetic
efficiencies of the components of the desalination unit at variable
operation conditions such as feed water temperature, outlet air
temperature, air to feed water mass ratio and salinity, in addition to
cooling water mass flow rate and inlet temperature, as well as
quantity of solar irradiance.
The results obtained indicate that the exergy efficiency of the
humidifier increases by increasing the mass ratio and decreasing the
outlet air temperature. In the other hand the exergy efficiency of the
condenser increases with the increase of this ratio and also with the
increase of the outlet air temperature.
Abstract: With the proliferation of mobile computing technology, mobile learning (m-learning) will play a vital role in the rapidly growing electronic learning market. However, the acceptance of m-learning by individuals is critical to the successful implementation of m-learning systems. Thus, there is a need to research the factors that affect users- intention to use m-learning. Based on an updated information system (IS) success model, data collected from 350 respondents in Taiwan were tested against the research model using the structural equation modeling approach. The data collected by questionnaire were analyzed to check the validity of constructs. Then hypotheses describing the relationships between the identified constructs and users- satisfaction were formulated and tested.
Abstract: In this paper, experimental testing and numerical analysis were used to investigate the effect of tube thickness on the face bending for concrete filled hollow sections connected to other structural members using Extended Hollobolts. Six samples were tested experimentally by applying pull-out load on the bolts. These samples were designed to fail by column face bending. The main variable in all tests is the column face thickness. Finite element analyses were also performed using ABAQUS 6.11 to extend the experimental results and to quantify the effect of column face thickness. Results show that, the column face thickness has a clear impact on the connection strength and stiffness. However, the amount of improvement in the connection stiffness by changing the column face thickness from 5mm to 6.3mm seems to be higher than that when increasing it from 6.3mm to 8mm. The displacement at which the bolts start pulling-out from their holes increased with the use of thinner column face due to the high flexibility of the section. At the ultimate strength, the yielding of the column face propagated to the column corner and there was no yielding in its walls. After the ultimate resistance is reached, the propagation of the yielding was mainly in the column face with a miner yielding in the walls.
Abstract: This paper describes a method to improve the robustness of a face recognition system based on the combination of two compensating classifiers. The face images are preprocessed by the appearance-based statistical approaches such as Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA). LDA features of the face image are taken as the input of the Radial Basis Function Network (RBFN). The proposed approach has been tested on the ORL database. The experimental results show that the LDA+RBFN algorithm has achieved a recognition rate of 93.5%
Abstract: In this study the effect of incorporation of recycled
glass-fibre reinforced polymer (GFRP) waste materials, obtained by
means of milling processes, on mechanical behaviour of polyester
polymer mortars was assessed. For this purpose, different contents of
recycled GFRP waste powder and fibres, with distinct size gradings,
were incorporated into polyester based mortars as sand aggregates
and filler replacements. Flexural and compressive loading capacities
were evaluated and found better than unmodified polymer mortars.
GFRP modified polyester based mortars also show a less brittle
behaviour, with retention of some loading capacity after peak load.
Obtained results highlight the high potential of recycled GFRP waste
materials as efficient and sustainable reinforcement and admixture for
polymer concrete and mortars composites, constituting an emergent
waste management solution.
Abstract: The increasingly sophisticated technologies have now been able to provide assistance for surgeons to improve surgical
performance through various training programs. Equally important to learning skills is the assessment method as it determines the learning and technical proficiency of a trainee. A consistent and
rigorous assessment system will ensure that trainees acquire the specific level of competency prior to certification. This paper
reviews the methods currently in use for assessment of surgical
skill and some modern techniques using computer-based
measurements and virtual reality systems for more quantitative
measurements
Abstract: It is a challenge to provide a wide range of queries to
database query systems for small mobile devices, such as the PDAs
and cell phones. Currently, due to the physical and resource
limitations of these devices, most reported database querying systems
developed for them are only offering a small set of pre-determined
queries for users to possibly pose. The above can be resolved by
allowing free-form queries to be entered on the devices. Hence, a
query language that does not restrict the combination of query terms
entered by users is proposed. This paper presents the free-form query
language and the method used in translating free-form queries to
their equivalent SQL statements.
Abstract: Multicarrier code-division multiple-access is one of the
effective techniques to gain its multiple access capability, robustness
against fading, and to mitigate the ISI. In this paper, we propose an
improved mulcarrier CDMA system with adaptive subchannel
allocation. We analyzed the performance of our proposed system in
frequency selective fading environment with narrowband interference
existing and compared it with that of parallel transmission over many
subchannels (namely, conventional MC-CDMA scheme) and
DS-CDMA system. Simulation results show that adaptive subchannel
allocation scheme, when used in conventional multicarrier CDMA
system, the performance will be greatly improved.
Abstract: In the planning point of view, it is essential to have
mode choice, due to the massive amount of incurred in transportation
systems. The intercity travellers in Libya have distinct features, as
against travellers from other countries, which includes cultural and
socioeconomic factors. Consequently, the goal of this study is to
recognize the behavior of intercity travel using disaggregate models,
for projecting the demand of nation-level intercity travel in Libya.
Multinomial Logit Model for all the intercity trips has been
formulated to examine the national-level intercity transportation in
Libya. The Multinomial logit model was calibrated using nationwide
revealed preferences (RP) and stated preferences (SP) survey. The
model was developed for deference purpose of intercity trips (work,
social and recreational). The variables of the model have been
predicted based on maximum likelihood method. The data needed for
model development were obtained from all major intercity corridors
in Libya. The final sample size consisted of 1300 interviews. About
two-thirds of these data were used for model calibration, and the
remaining parts were used for model validation. This study, which is
the first of its kind in Libya, investigates the intercity traveler’s
mode-choice behavior. The intercity travel mode-choice model was
successfully calibrated and validated. The outcomes indicate that, the
overall model is effective and yields higher precision of estimation.
The proposed model is beneficial, due to the fact that, it is receptive
to a lot of variables, and can be employed to determine the impact of
modifications in the numerous characteristics on the need for various
travel modes. Estimations of the model might also be of valuable to
planners, who can estimate possibilities for various modes and
determine the impact of unique policy modifications on the need for
intercity travel.
Abstract: Sediment formation and its transport along the river course is considered as important hydraulic consideration in river engineering. Their impact on the morphology of rivers on one hand and important considerations of which in the design and construction of the hydraulic structures on the other has attracted the attention of experts in arid and semi-arid regions. Under certain conditions where the momentum energy of the flow stream reaches a specific rate, the sediment materials start to be transported with the flow. This can usually be analyzed in two different categories of suspended and bed load materials. Sedimentation phenomenon along the waterways and the conveyance of vast volume of materials into the canal networks can potentially influence water abstraction in the intake structures. This can pose a serious threat to operational sustainability and water delivery performance in the canal networks. The situation is serious where ineffective watershed management (poor vegetation cover in the water basin) is the underlying cause of soil erosion which feeds the materials into the waterways that intern would necessitate comprehensive study. The present paper aims to present an analytical investigation of the sediment process in the waterways on one hand and estimation of the sediment load transport into the lined canals using the SHARC software on the other. For this reason, the paper focuses on the comparative analysis of the hydraulic behaviors of the Sabilli main canal that feeds the pumping station with that of the Western canal in the Greater Dezful region to identify effective factors in sedimentation and ways of mitigating their impact on water abstraction in the canal systems. The method involved use of observational data available in the Dezful Dastmashoon hydrometric station along a 6 km waterway of the Sabilli main canal using the SHARC software to estimate the suspended load concentration and bed load materials. Results showed the transport of a significant volume of sediment loads from the waterways into the canal system which is assumed to have arisen from the absence of stilling basin on one hand and the gravity flow on the other has caused serious challenges. This is contrary to what occurs in the Sabilli canal, where the design feature which incorporates a settling basin just before the pumping station is the major cause of reduced sediment load transport into the canal system.Results showed that modification of the present design features by constructing a settling basin just upstream of the western intake structure can considerably reduce the entry of sediment materials into the canal system. Not only this can result in the sustainability of the hydraulic structures but can also improve operational performance of water conveyance and distribution system, all of which are the pre-requisite to secure reliable and equitable water delivery regime for the command area.
Abstract: An area-integrating method that uses the technique of total integrated light scatter for evaluating the root mean square height of the surface Sq has been presented in the paper. It is based on the measurement of the scatter power using a flat photodiode integrator rather than an optical sphere or a hemisphere. By this means, one can obtain much less expensive and smaller instruments than traditional ones. Thanks to this, they could find their application for surface control purposes, particularly in small and medium size enterprises. A description of the functioning of the measuring unit as well as the impact caused by different factors on its properties is presented first. Next, results of measurements of the Sq values performed for optical, silicon and metal samples have been shown. It has been also proven that they are in a good agreement with the results obtained using the Ulbricht sphere instrument.
Abstract: This paper presents results obtained from the
numerical solution for the flow past an oscillating circular cylinder at
Reynolds number of 200. The frequency of oscillation was fixed to
the vortex shedding frequency from a fixed cylinder, f0, while the
amplitudes of oscillations were varied from to 1.1a, where a
represents the radius of the cylinder. The response of the flow
through the fluid forces acting on the surface of the cylinder are
investigated. The lock-on phenomenon is captured at low oscillation
amplitudes.
Abstract: Rapid prototyping (RP) techniques are a group of
advanced manufacturing processes that can produce custom made
objects directly from computer data such as Computer Aided Design
(CAD), Computed Tomography (CT) and Magnetic Resonance
Imaging (MRI) data. Using RP fabrication techniques, constructs
with controllable and complex internal architecture with appropriate
mechanical properties can be achieved. One of the attractive and
promising utilization of RP techniques is related to tissue engineering
(TE) scaffold fabrication. Tissue engineering scaffold is a 3D
construction that acts as a template for tissue regeneration. Although
several conventional techniques such as solvent casting and gas
forming are utilized in scaffold fabrication; these processes show
poor interconnectivity and uncontrollable porosity of the produced
scaffolds. So, RP techniques become the best alternative fabrication
methods of TE scaffolds. This paper reviews the current state of the
art in the area of tissue engineering scaffolds fabrication using
advanced RP processes, as well as the current limitations and future
trends in scaffold fabrication RP techniques.
Abstract: One of the primary uses of higher order statistics in
signal processing has been for detecting and estimation of non-
Gaussian signals in Gaussian noise of unknown covariance. This is
motivated by the ability of higher order statistics to suppress additive
Gaussian noise. In this paper, several methods to test for non-
Gaussianity of a given process are presented. These methods include
histogram plot, kurtosis test, and hypothesis testing using cumulants
and bispectrum of the available sequence. The hypothesis testing is
performed by constructing a statistic to test whether the bispectrum
of the given signal is non-zero. A zero bispectrum is not a proof of
Gaussianity. Hence, other tests such as the kurtosis test should be
employed. Examples are given to demonstrate the performance of the
presented methods.
Abstract: This paper addresses the problems encountered by conventional distance relays when protecting double-circuit transmission lines. The problems arise principally as a result of the mutual coupling between the two circuits under different fault conditions; this mutual coupling is highly nonlinear in nature. An adaptive protection scheme is proposed for such lines based on application of artificial neural network (ANN). ANN has the ability to classify the nonlinear relationship between measured signals by identifying different patterns of the associated signals. One of the key points of the present work is that only current signals measured at local end have been used to detect and classify the faults in the double circuit transmission line with double end infeed. The adaptive protection scheme is tested under a specific fault type, but varying fault location, fault resistance, fault inception angle and with remote end infeed. An improved performance is experienced once the neural network is trained adequately, which performs precisely when faced with different system parameters and conditions. The entire test results clearly show that the fault is detected and classified within a quarter cycle; thus the proposed adaptive protection technique is well suited for double circuit transmission line fault detection & classification. Results of performance studies show that the proposed neural network-based module can improve the performance of conventional fault selection algorithms.
Abstract: An innovative approach utilizing highly alkaline oil
shale waste ash and carbon dioxide gas (CO2), associated with power
production, as a resource for production of precipitated calcium
carbonate (PCC) is introduced in this paper. The specifics and
feasibility of the integrated ash valorization and CO2 sequestration
process by indirect aqueous carbonation of lime-consisting ash were
elaborated and the main parameters established. Detailed description
of the formed precipitates was included. Complimentary carbonation
experiments with commercial CaO fine powder were conducted for
comparative characterization of the final products obtained on the
basis of two different raw materials. Finally, the expected CO2
uptake was evaluated.
Abstract: When studying electronics, hands-on experience is considered to be very valuable for a better understanding of the concepts of electricity and electronics. Students lacking sufficient time in the lab are often put at disadvantage. A way to overcome this, is by using interactive multimedia in a virtual environment. Instead of proposing another new ad-hoc simulator for e-learning, we propose in this paper an e-learning platform integrating the SPICE simulator as a web service. This enables to make use of all the functions of the de-facto standard simulator SPICE inelectronics when developing new simulations.
Abstract: The paper presents an analysis of linkages and
structures of co-operation and their intensity like the potential for the
establishment of clusters in the Central and Eastern (Pannonian)
Croatian. Starting from the theoretical elaboration of the need for
entrepreneurs to organize through the cluster model and the terms of
their self-actualization, related to the importance of traditional values
in terms of benefits, social capital and assess where the company now
is, in order to prove the need to create their own identity in terms of
clustering. The institutional dimensions of social capital where the
public sector has the best role in creating the social structure of
clusters, and social dimensions of social capital in terms of trust,
cooperation and networking will be analyzed to what extent the trust
and coherency are present between companies in the Brod posavina
and Pozega slavonia County, expressed through the readiness of
inclusion in clusters in the NUTS II region - Central and Eastern
(Pannonian) Croatia, as a homogeneous economic entity, with
emphasis on limiting factors that stand in the way of greater
competitiveness.
Abstract: The state of the art in instructional design for
computer-assisted learning has been strongly influenced by advances
in information technology, Internet and Web-based systems. The
emphasis of educational systems has shifted from training to
learning. The course delivered has also been changed from large
inflexible content to sequential small chunks of learning objects. The
concepts of learning objects together with the advanced technologies
of Web and communications support the reusability, interoperability,
and accessibility design criteria currently exploited by most learning
systems. These concepts enable just-in-time learning. We propose to
extend theses design criteria further to include the learnability
concept that will help adapting content to the needs of learners. The
learnability concept offers a better personalization leading to the
creation and delivery of course content more appropriate to
performance and interest of each learner. In this paper we present a
new framework of learning environments containing knowledge
discovery as a tool to automatically learn patterns of learning
behavior from learners' profiles and history.
Abstract: Laser soldering is based on applying some soldering material (albumin) onto the approximated edges of the cut and heating the solder (and the underlying tissues) by a laser beam. Endogenous and exogenous materials such as indocyanine green (ICG) are often added to solders to enhance light absorption. Gold nanoshells are new materials which have an optical response dictated by the plasmon resonance. The wavelength at which the resonance occurs depends on the core and shell sizes, allowing nanoshells to be tailored for particular applications. The purposes of this study was use combination of ICG and different concentration of gold nanoshells for skin tissue soldering and also to examine the effect of laser soldering parameters on the properties of repaired skin. Two mixtures of albumin solder and different combinations of ICG and gold nanoshells were prepared. A full thickness incision of 2×20 mm2 was made on the surface and after addition of mixtures it was irradiated by an 810nm diode laser at different power densities. The changes of tensile strength σt due to temperature rise, number of scan (Ns), and scan velocity (Vs) were investigated. The results showed at constant laser power density (I), σt of repaired incisions increases by increasing the concentration of gold nanoshells in solder, Ns and decreasing Vs. It is therefore important to consider the tradeoff between the scan velocity and the surface temperature for achieving an optimum operating condition. In our case this corresponds to σt =1800 gr/cm2 at I~ 47 Wcm-2, T ~ 85ºC, Ns =10 and Vs=0.3mms-1.