Abstract: Software maintenance, which involves making enhancements, modifications and corrections to existing software systems, consumes more than half of developer time. Specification comprehensibility plays an important role in software maintenance as it permits the understanding of the system properties more easily and quickly. The use of formal notation such as B increases a specification-s precision and consistency. However, the notation is regarded as being difficult to comprehend. Semi-formal notation such as the Unified Modelling Language (UML) is perceived as more accessible but it lacks formality. Perhaps by combining both notations could produce a specification that is not only accurate and consistent but also accessible to users. This paper presents an experiment conducted on a model that integrates the use of both UML and B notations, namely UML-B, versus a B model alone. The objective of the experiment was to evaluate the comprehensibility of a UML-B model compared to a traditional B model. The measurement used in the experiment focused on the efficiency in performing the comprehension tasks. The experiment employed a cross-over design and was conducted on forty-one subjects, including undergraduate and masters students. The results show that the notation used in the UML-B model is more comprehensible than the B model.
Abstract: In this study, the dispersion of heavy particles line in
an isotropic and incompressible three-dimensional turbulent flow has
been studied using the Kinematic Simulation techniques to find out
the evolution of the line fractal dimension. The fractal dimension of
the line is found in the case of different particle gravity (in practice,
different values of particle drift velocity) in the presence of small
particle inertia with a comparison with that obtained in the diffusion
case of material line at the same Reynolds number. It can be
concluded for the dispersion of heavy particles line in turbulent flow
that the particle gravity affect the fractal dimension of the line for
different particle gravity velocities in the range 0.2 < W < 2. With
the increase of the particle drift velocity, the fractal dimension of the
line decreases which may be explained as the particles pass many
scales in their journey in the direction of the gravity and the particles
trajectories do not affect by these scales at high particle drift
velocities.
Abstract: Data hiding into text documents itself involves pretty
complexities due to the nature of text documents. A robust text
watermarking scheme targeting an object based environment is
presented in this research. The heart of the proposed solution
describes the concept of watermarking an object based text document
where each and every text string is entertained as a separate object
having its own set of properties. Taking advantage of the z-ordering
of objects watermark is applied with the z-axis letting zero fidelity
disturbances to the text. Watermark sequence of bits generated
against user key is hashed with selected properties of given
document, to determine the bit sequence to embed. Bits are
embedded along z-axis and the document has no fidelity issues when
printed, scanned or photocopied.
Abstract: An effective approach for realizing the binary tree structure, representing a combinational logic functionality with enhanced throughput, is discussed in this paper. The optimization in maximum operating frequency was achieved through delay minimization, which in turn was possible by means of reducing the depth of the binary network. The proposed synthesis methodology has been validated by experimentation with FPGA as the target technology. Though our proposal is technology independent, yet the heuristic enables better optimization in throughput even after technology mapping for such Boolean functionality; whose reduced CNF form is associated with a lesser literal cost than its reduced DNF form at the Boolean equation level. For cases otherwise, our method converges to similar results as that of [12]. The practical results obtained for a variety of case studies demonstrate an improvement in the maximum throughput rate for Spartan IIE (XC2S50E-7FT256) and Spartan 3 (XC3S50-4PQ144) FPGA logic families by 10.49% and 13.68% respectively. With respect to the LUTs and IOBUFs required for physical implementation of the requisite non-regenerative logic functionality, the proposed method enabled savings to the tune of 44.35% and 44.67% respectively, over the existing efficient method available in literature [12].
Abstract: The main objective of this study was to determine if a
minimal increase in road light level (luminance) could lead to
improved driving performance among older adults. Older, middleaged
and younger adults were tested in a driving simulator following
vision and cognitive screening. Comparisons were made for the
performance of simulated night driving under two road light
conditions (0.6 and 2.5 cd/m2). At each light level, the effects of self
reported night driving avoidance were examined along with the
vision/cognitive performance. It was found that increasing road light
level from 0.6 cd/m2 to 2.5 cd/m2 resulted in improved recognition of
signage on straight highway segments. The improvement depends on
different driver-related factors such as vision and cognitive abilities,
and confidence. On curved road sections, the results showed that
driver-s performance worsened. It is concluded that while increasing
road lighting may be helpful to older adults especially for sign
recognition, it may also result in increased driving confidence and
thus reduced attention in some driving situations.
Abstract: This paper provides an exergy analysis of the multistage refrigeration cycle used for C2+ recovery plant. The behavior of an industrial refrigeration cycle with refrigerant propane has been investigated by the exergy method. A computational model based on the exergy analysis is presented for the investigation of the effects of the valves on the exergy losses, the second law of efficiency, and the coefficient of performance (COP) of a vapor compression refrigeration cycle. The equations of exergy destruction and exergetic efficiency for the main cycle components such as evaporators, condensers, compressors, and expansion valves are developed. The relations for the total exergy destruction in the cycle and the cycle exergetic efficiency are obtained. An ethane recovery unit with its refrigeration cycle has been simulated to prepare the exergy analysis. Using a typical actual work input value; the exergetic efficiency of the refrigeration cycle is determined to be 39.90% indicating a great potential for improvements. The simulation results reveal that the exergetic efficiencies of the heat exchanger and expansion sections get the lowest rank among the other compartments of refrigeration cycle. Refrigeration calculations have been carried out through the analysis of T–S and P–H diagrams where coefficient of performance (COP) was obtained as 1.85. The novelty of this article includes the effect and sensitivity analysis of molar flow, pressure drops and temperature on the exergy efficiency and coefficient of performance of the cycle.
Abstract: Ciprofloxacin (CIP) and Carbamazepine (CBZ), nonbiodegradable pharmaceutical residues, were become emerging pollutants in several aquatic environments. The objectives of this research were to study the possibility to recover these pharmaceuticals residues from pharmaceutical wastewater by increasing the selective adsorption on synthesized functionalized porous silicate, comparing with powdered activated carbon (PAC). Hexagonal mesoporous silicate (HMS), functionalized HMSs (3- aminopropyltriethoxy, 3- mercaptopropyltrimethoxy and noctyldimethyl) were synthesized and characterized physico-chemical characteristics. Obtained adsorption kinetics and isotherms showed that 3-mercaptopropyltrimethoxy functional groups grafted on HMS provided highest CIP and CBZ adsorption capacities; however, it was still lower than that of PAC. The kinetic results were compatible with pseudo-second order. The hydrophobicity and hydrogen bonding might play a key role on the adsorption. Furthermore, the capacities were affected by varying pH values due to the strength of hydrogen bonding between targeted compounds and adsorbents. Electrostatic interaction might not affect the adsorption capacities.
Abstract: A complex valued neural network is a neural network, which consists of complex valued input and/or weights and/or thresholds and/or activation functions. Complex-valued neural networks have been widening the scope of applications not only in electronics and informatics, but also in social systems. One of the most important applications of the complex valued neural network is in image and vision processing. In Neural networks, radial basis functions are often used for interpolation in multidimensional space. A Radial Basis function is a function, which has built into it a distance criterion with respect to a centre. Radial basis functions have often been applied in the area of neural networks where they may be used as a replacement for the sigmoid hidden layer transfer characteristic in multi-layer perceptron. This paper aims to present exhaustive results of using RBF units in a complex-valued neural network model that uses the back-propagation algorithm (called 'Complex-BP') for learning. Our experiments results demonstrate the effectiveness of a Radial basis function in a complex valued neural network in image recognition over a real valued neural network. We have studied and stated various observations like effect of learning rates, ranges of the initial weights randomly selected, error functions used and number of iterations for the convergence of error on a neural network model with RBF units. Some inherent properties of this complex back propagation algorithm are also studied and discussed.
Abstract: Molodstov-s soft sets theory was originally proposed
as general mathematical tool for dealing with uncertainty problems. The matrix form has been introduced in soft set and some of its
properties have been discussed. However, the formulation of soft
matrix in group decision making problem only with equal importance
weights of criteria, which does not show the true opinion of decision maker on each criteria. The aim of this paper is to propose a method
for solving group decision making problem incorporating the importance of criteria by using soft matrices in a more objective manner. The weight of each criterion is calculated by using the Analytic Hierarchy Process (AHP) method. An example of house
selection process is given to illustrate the effectiveness of the proposed method.
Abstract: This paper is taken into consideration the problem of cryptanalysis of stream ciphers. There is some attempts need to improve the existing attacks on stream cipher and to make an attempt to distinguish the portions of cipher text obtained by the encryption of plain text in which some parts of the text are random and the rest are non-random. This paper presents a tutorial introduction to symmetric cryptography. The basic information theoretic and computational properties of classic and modern cryptographic systems are presented, followed by an examination of the application of cryptography to the security of VoIP system in computer networks using LFSR algorithm. The implementation program will be developed Java 2. LFSR algorithm is appropriate for the encryption and decryption of online streaming data, e.g. VoIP (voice chatting over IP). This paper is implemented the encryption module of speech signals to cipher text and decryption module of cipher text to speech signals.
Abstract: Polyurethanes (PURs) are very versatile polymeric
materials with a wide range of physical and chemical properties.
PURs have desirable properties such as high abrasion resistance, tear
strength, shock absorption, flexibility and elasticity. Although they
have relatively poor thermal stability, this can be improved by using
treated clay. Polyurethane/clay nanocomposites have been
synthesized from renewable sources. A polyol for the production of
polyurethane by reaction with an isocyanate was obtained by the
synthesis of palm oil-based oleic acid with glycerol. Dodecylbenzene
sulfonic acid (DBSA) was used as catalyst and emulsifier. The
unmodified clay (kunipia-F) was treated with cetyltrimethyl
ammonium bromide (CTAB-mont) and octadodecylamine (ODAmont).
The d-spacing in CTAB-mont and ODA-mont were 1.571 nm
and 1.798 nm respectively and larger than that of the pure-mont
(1.142 nm). The organoclay was completely intercalated in the
polyurethane, as confirmed by a wide angle x-ray diffraction
(WAXD) pattern.
The results showed that adding clay demonstrated better thermal
stability in comparison with the virgin polyurethane. Onset
degradation of pure PU is at 200oC, and is lower than that of the
CTAB-mont PU and ODA-mont PU which takes place at about
318oC and 330oC, respectively. The mechanical properties (including
the dynamic mechanical properties) of pure polyurethane (PU) and
PU/clay nanocomposites, were measured. The modified organoclay
had a remarkably beneficial effect on the strength and elongation at
break of the nanocomposites, which both increased with increasing
clay content with the increase of the tensile strength of more than
214% and 267% by the addition of only 5 wt% of the
montmorillonite CTAB-mont PU and ODA-mont PU, respectively.
Abstract: The paper presents the case study of hazard
identification and sensitivity of potential resource of emergency
water supply as part of the application of methodology classifying
the resources of drinking water for emergency supply of population.
The case study has been carried out on a selected resource of
emergency water supply in one region of the Czech Republic. The
hazard identification and sensitivity of potential resource of
emergency water supply is based on a unique procedure and
developed general registers of selected types of hazards and
sensitivities. The registers have been developed with the help of the
“Fault Tree Analysis” method in combination with the “What if
method”. The identified hazards for the assessed resource include
hailstorms and torrential rains, drought, soil erosion, accidents of
farm machinery, and agricultural production. The developed registers
of hazards and vulnerabilities and a semi-quantitative assessment of
hazards for individual parts of hydrological structure and
technological elements of presented drilled wells are the basis for a
semi-quantitative risk assessment of potential resource of emergency
supply of population and the subsequent classification of such
resource within the system of crisis planning.
Abstract: The results obtained after incorporating the competence “creativity" to the subject Technical Drawing of the first course of the Degree in Forestry, Technical University of Madrid, are presented in this study.At first, learning activities which could serve two functions at the same time -developing students- creativity and developing other specific competences of the subject- were considered. Besides, changes in the assessment procedure were made and a method which analyzes two aspects of the assessment of the competence creativity was established. On the one hand, the products are evaluated by analyzing the outcomes obtained by students in the essays suggested and by establishing a parameter to assess the creativity expressed in those essays. On the other, an assessment of the student is directly carried out through a psychometric test which has been previously chosen by the team.Moreover, these results can be applied to similar or could be of general application.
Abstract: Genetic algorithms (GAs) have been widely used for
global optimization problems. The GA performance depends highly
on the choice of the search space for each parameter to be optimized.
Often, this choice is a problem-based experience. The search space
being a set of potential solutions may contain the global optimum
and/or other local optimums. A bad choice of this search space
results in poor solutions. In this paper, our approach consists in
extending the search space boundaries during the GA optimization,
only when it is required. This leads to more diversification of GA
population by new solutions that were not available with fixed search
space boundaries. So, these dynamic search spaces can improve the
GA optimization performances. The proposed approach is applied to
power system stabilizer optimization for multimachine power system
(16-generator and 68-bus). The obtained results are evaluated and
compared with those obtained by ordinary GAs. Eigenvalue analysis
and nonlinear system simulation results show the effectiveness of the
proposed approach to damp out the electromechanical oscillation and
enhance the global system stability.
Abstract: Industrial surveys shows that manufacturing
companies define the qualities of thermal removing process based on
the dimension and physical appearance of the cutting material
surface. Therefore, the roughness of the surface area of the material
cut by the plasma arc cutting process and the rate of the removed
material by the manual plasma arc cutting machine was importantly
considered. Plasma arc cutter Selco Genesis 90 was used to cut
Standard AISI 1017 Steel of 200 mm x100 mm x 6 mm manually
based on the selected parameters setting. The material removal rate
(MRR) was measured by determining the weight of the specimens
before and after the cutting process. The surface roughness (SR)
analysis was conducted using Mitutoyo CS-3100 to determine the
average roughness value (Ra). Taguchi method was utilized to
achieve optimum condition for both outputs studied. The
microstructure analysis in the region of the cutting surface is
performed using SEM. The results reveal that the SR values are
inversely proportional to the MRR values. The quality of the surface
roughness depends on the dross peak that occurred after the cutting
process.
Abstract: Sensors have been used in various kinds of academic
fields and applications. In this article, we propose the idea of
modularized sensors that combine multiple sensor modules into a
unique sensor. We divide a sensor into several units according to
functionalities. Each unit has different sensor modules, which share
the same type of connectors and can be serially and arbitrarily
connected each other. A user can combine different sensor modules
into a sensor platform according to requirements. Compared with
current modularized sensors, the proposed sensor platform is highly
flexible and reusable. We have implemented the prototype of the
proposed sensor platform, and the experimental results show the
proposed platform can work correctly.
Abstract: In this paper, a new dependable algorithm based on an adaptation of the standard variational iteration method (VIM) is used for analyzing the transition from steady convection to chaos for lowto-intermediate Rayleigh numbers convection in porous media. The solution trajectories show the transition from steady convection to chaos that occurs at a slightly subcritical value of Rayleigh number, the critical value being associated with the loss of linear stability of the steady convection solution. The VIM is treated as an algorithm in a sequence of intervals for finding accurate approximate solutions to the considered model and other dynamical systems. We shall call this technique as the piecewise VIM. Numerical comparisons between the piecewise VIM and the classical fourth-order Runge–Kutta (RK4) numerical solutions reveal that the proposed technique is a promising tool for the nonlinear chaotic and nonchaotic systems.
Abstract: Cassava is one of the top five crops in Cameroon. Its
evolution has remained constant since the independence period and
the production has more than tripled. It is a crop with multiple
industrial capacities but the sector-s business opportunities are
underexploited. Using Strengths, Weaknesses, Opportunities and
Threats analysis method, this paper examines the cassava actual state.
It appraises the sector-s strengths (S), considers suitable measures to
strengthen weaknesses (W), evaluates strategies to fully benefit from
the sector numerous business opportunities (O) and explore means to
convert threats (T) into opportunities. Data were collected from the
ministry of agriculture and rural development and different actors.
The results show that cassava sector embodies many business
opportunities and stands as a raw material provider for many
industries but ultimately requires challenges to be tackled
appropriately.
Abstract: Dual bell nozzle is a promising one among the altitude
adaptation nozzle concepts, which offer increased nozzle
performance in rocket engines. Its advantage is the simplicity it offers
due to the absence of any additional mechanical device or movable
parts. Hence it offers reliability along with improved nozzle
performance as demanded by future launch vehicles. Among other
issues, the flow transition to the extension nozzle of a dual bell
nozzle is one of the major issues being studied in the development of
dual bell nozzle. A parameter named over-expansion factor, which
controls the value of the wall inflection angle, has been reported to
have substantial influence in this transition process. This paper
studies, through CFD and cold flow experiments, the effect of overexpansion
factor on flow transition in dual bell nozzles.
Abstract: In determining the electromagnetic properties of
magnetic materials, hysteresis modeling is of high importance. Many
models are available to investigate those characteristics but they tend
to be complex and difficult to implement. In this paper a new
qualitative hysteresis model for ferromagnetic core is presented,
based on the function approximation capabilities of adaptive neuro
fuzzy inference system (ANFIS). The proposed ANFIS model
combined the neural network adaptive capabilities and the fuzzy
logic qualitative approach can restored the hysteresis curve with a
little RMS error. The model accuracy is good and can be easily
adapted to the requirements of the application by extending or
reducing the network training set and thus the required amount of
measurement data.