Abstract: Using a set of confidence intervals, we develop a
common approach, to construct a fuzzy set as an estimator for
unknown parameters in statistical models. We investigate a method
to derive the explicit and unique membership function of such fuzzy
estimators. The proposed method has been used to derive the fuzzy
estimators of the parameters of a Normal distribution and some
functions of parameters of two Normal distributions, as well as the
parameters of the Exponential and Poisson distributions.
Abstract: Recent financial international scandals around the world have led to a number of investigations into the effectiveness of corporate governance practices and audit quality. Although evidence of corporate governance practices and audit quality exists from developed economies, very scanty studies have been conducted in Egypt where corporate governance is just evolving. Therefore, this study provides evidence on the effectiveness of corporate governance practices and audit quality from a developing country. The data for analysis are gathered from the top 50 most active companies in the Egyptian Stock Exchange, covering the three year period 2007-2009. Logistic regression was used in investigating the questions that were raised in the study. Findings from the study show that board independence; CEO duality and audit committees significantly have relationship with audit quality. The results also, indicate that institutional investor and managerial ownership have no significantly relationship with audit quality. Evidence also exist that size of the company; complexity and business leverage are important factors in audit quality for companies quoted on the Egypt Stock Exchange.
Abstract: An effective approach for unbalanced three-phase
distribution power flow solutions is proposed in this paper. The
special topological characteristics of distribution networks have been
fully utilized to make the direct solution possible. Two matrices–the
bus-injection to branch-current matrix and the branch-current to busvoltage
matrix– and a simple matrix multiplication are used to
obtain power flow solutions. Due to the distinctive solution
techniques of the proposed method, the time-consuming LU
decomposition and forward/backward substitution of the Jacobian
matrix or admittance matrix required in the traditional power flow
methods are no longer necessary. Therefore, the proposed method is
robust and time-efficient. Test results demonstrate the validity of the
proposed method. The proposed method shows great potential to be
used in distribution automation applications.
Abstract: In this paper a sliding-mode torque and flux control is
designed for encoderless synchronous reluctance motor drive. The
sliding-mode plus PI controllers are designed in the stator-flux field
oriented reference frame which is able to track the mentioned
reference signals with a minimum pulsations in the state condition. In
addition, with these controllers a fast dynamic response is also
achieved for the drive system. The proposed control scheme is robust
subject to parameters variation except to stator resistance. To solve
this problem a simple estimator is used for on-line detecting of this
parameter. Moreover, the rotor position and speed are estimated by
on-line obtaining of the stator-flux-space vector. The effectiveness
and capability of the proposed control approach is verified by both
the simulation and experimental results.
Abstract: This study mainly aims at assessing the level of
microbial pollution of the water used in the chair system in dental
clinics. For this purpose 36 samples have been randomly collected
from a number of dental surgeries in the city of Tripoli in Libya.
However, 32 of the samples have tested positive to microbial
pollution including 13 of the samples, which have tested positives to
Pseudomonas aeruginosa. Based on the results of the test a further
investigation of the biofilms incorporated within the dental chair
system has been conducted. The laboratory tests of biofilms with
similar design to those found in dental chairs have proved that
bacterial pollution takes place through saliva of the patients who use
the chairs, and that this saliva is rich with nutrients which provides a
suitable breeding ground for all types of bacteria.
Abstract: Oxide scale thickness measurements are used in assessing the life of different components operating at high temperature environment. Such measurements provide an approximation for the temperature inside components such as reheater and superheater tubes. A number of failures were encountered in one of the boilers in one of Kuwaiti power plants. These failure were mainly in the first row of the primary super heater tubes, therefore, the specialized engineer decide to replace them during the annual shutdown. As a tool for failure analysis, oxide scale thickness measurement were used to investigate the temperature distribution in these tubes. In this paper, the oxide scale thickness of these tubes were measured and used for analysis. The measurements provide an illustration of the distribution of heat transfer of the primary superheater tubes in the boiler system. Remarks and analysis about the design of the boiler are also provided.
Abstract: The Egyptian Bacillus thuringiensis isolate (M5) produce crystal proteins that is toxic against insects was irradiated with UV light to induce mutants. Upon testing 10 of the resulting mutants for their toxicity against cotton leafworm larvae, the three mutants 62, 64 and 85 proved to be the most toxic ones. Upon testing these mutants along with their parental isolate by SDS-PAGE analysis of spores-crystals proteins as well as vegetative cells proteins, new induced bands appeared in the three mutants by UV radiation and also they showed disappearance of some other bands as compared with the wild type isolate. Multiplex PCR technique, with five sets of specific primers, was used to detect the three types of cryI genes cryIAa, cryIAb and cryIAc. Results showed that these three genes exist, as distinctive bands, in the wild type isolate (M5) as well as in mutants 62 and 85, while the mutant 64 had two distinctive bands of cryIAb and cryIAc genes, and a faint band of cryI Aa gene. Finally, these results revealed that mutant 62 is considered as the promising mutant since it is UV resistant, highly toxic against Spodoptera littoralis and active against a wide range of Lepidopteran insects.
Abstract: In this article, we propose a methodology for the
characterization of the suspended matter along Algiers-s bay. An
approach by multi layers perceptron (MLP) with training by back
propagation of the gradient optimized by the algorithm of Levenberg
Marquardt (LM) is used. The accent was put on the choice of the
components of the base of training where a comparative study made
for four methods: Random and three alternatives of classification by
K-Means. The samples are taken from suspended matter image,
obtained by analytical model based on polynomial regression by
taking account of in situ measurements. The mask which selects the
zone of interest (water in our case) was carried out by using a multi
spectral classification by ISODATA algorithm. To improve the
result of classification, a cleaning of this mask was carried out using
the tools of mathematical morphology. The results of this study
presented in the forms of curves, tables and of images show the
founded good of our methodology.
Abstract: This paper proposes different methods for estimation
of the harmonic currents of the single-phase diode bridge rectifier. Both simple and advanced methods are compared and the models are
put into a context of practical use for calculating the harmonic distortion in a typical application. Finally, the different models are
compared to measurements of a real application and convincing results are achieved.
Abstract: For best collaboration, Asynchronous tools and particularly the discussion forums are the most used thanks to their flexibility in terms of time. To convey only the messages that belong to a theme of interest of the tutor in order to help him during his tutoring work, use of a tool for classification of these messages is indispensable. For this we have proposed a semantics classification tool of messages of a discussion forum that is based on LSA (Latent Semantic Analysis), which includes a thesaurus to organize the vocabulary. Benefits offered by formal ontology can overcome the insufficiencies that a thesaurus generates during its use and encourage us then to use it in our semantic classifier. In this work we propose the use of some functionalities that a OWL ontology proposes. We then explain how functionalities like “ObjectProperty", "SubClassOf" and “Datatype" property make our classification more intelligent by way of integrating new terms. New terms found are generated based on the first terms introduced by tutor and semantic relations described by OWL formalism.
Abstract: The spreading characteristics of acoustically excited
swirling double-concentric jets were studied experimentally. The
central jet was acoustically excited at low and high pulsation
intensities. A smoke wire flow visualization and a hot-wire
anemometer velocity measurement results show that excitation forces
a vortex ring to roll-up from the edge of the central tube during each
excitation period. At low pulsation intensities, the vortex ring evolves
downstream, and eventually breaks up into turbulent eddies. At high
pulsation intensities, the primary vortex ring evolves and a series of
trailing vortex rings form during the same period of excitation. The
trailing vortex rings accelerate while evolving downstream and
overtake the primary vortex ring within the same cycle. In the
process, the primary vortex ring becomes unstable and breaks up
early. The effect of the fast traveling trailing vortex rings combined
with the swirl motion of the annular flow improve jet spreading
compared with the naturally evolving jets.
Abstract: The main aims in this research are to study the solid
waste generation in the Faculty of Engineering and Built
Environment in the UKM and at the same time to determine
composition and some of the waste characteristics likewise: moisture
content, density, pH and C/N ratio. For this purpose multiple
campaigns were conducted to collect the wastes produced in all
hostels, faculties, offices and so on, during 24th of February till 2nd
of March 2009, measure and investigate them with regard to both
physical and chemical characteristics leading to highlight the
necessary management policies. Research locations are Faculty of
Engineering and the Canteen nearby that. From the result gained, the
most suitable solid waste management solution will be proposed to
UKM. The average solid waste generation rate in UKM is 203.38
kg/day. The composition of solid waste generated are glass, plastic,
metal, aluminum, organic and inorganic waste and others waste.
From the laboratory result, the average moisture content, density, pH
and C/N ratio values from the solid waste generated are 49.74%,
165.1 kg/m3, 5.3, and 7:1 respectively. Since, the food waste (organic
waste) were the most dominant component, around 62% from the
total waste generated hence, the most suitable solid waste
management solution is composting.
Abstract: Traditional principal components analysis (PCA)
techniques for face recognition are based on batch-mode training
using a pre-available image set. Real world applications require that
the training set be dynamic of evolving nature where within the
framework of continuous learning, new training images are
continuously added to the original set; this would trigger a costly
continuous re-computation of the eigen space representation via
repeating an entire batch-based training that includes the old and new
images. Incremental PCA methods allow adding new images and
updating the PCA representation. In this paper, two incremental
PCA approaches, CCIPCA and IPCA, are examined and compared.
Besides, different learning and testing strategies are proposed and
applied to the two algorithms. The results suggest that batch PCA is
inferior to both incremental approaches, and that all CCIPCAs are
practically equivalent.
Abstract: In the present study, the rate of NOx emission in a
combustion chamber working in conventional combustion and High
Temperature Air Combustion (HiTAC) system are examined using
CFD modeling. The effect of peak temperature, combustion air
temperature and oxygen concentration on NOx emission rate was
undertaken. Results show that in a fixed oxygen concentration,
increasing the preheated air temperature will increase the peak
temperature and NOx emission rate. In addition, it was observed that
the reduction of the oxygen concentration in the fixed preheated air
temperature decreases the peak temperature and NOx emission rate.
On the other hand, the results show that increase of preheated air
temperature at various oxygen concentrations increases the NOx
emission rate. However, the rate of increase in HiTAC conditions is
quite lower than the conventional combustion. The modeling results
show that the NOx emission rate in HiTAC combustion is 133% less
than that of the conventional combustion.
Abstract: In social network analysis the mean nodal degree and
density of the graph can be considered as a measure of the activity of
all actors in the network and this is an important property of a graph
and for making comparisons among networks. Since subjects in a
family or organization are subject to common environment factors, it
is prime interest to study the association between responses.
Therefore, we study the distribution of the mean nodal degree and
density of the graph under correlated binary units. The cross product
ratio is used to capture the intra-units association among subjects.
Computer program and an application are given to show the benefits
of the method.
Abstract: Vinegar is a precious food additive and complement as well as effective preservative against food spoilage. Recently traditional vinegar production has been improved using various natural substrates and fruits such as grape, palm, cherry, coconut, date, sugarcane, rice and balsam. These neoclassical fermentations resulted in several vinegar types with different tastes, fragrances and nutritional values because of applying various acetic acid bacteria as starters. Acetic acid bacteria include genera Acetobacter, Gluconacetobacter and Gluconobacter according to latest edition of Bergy-s Manual of Systematic Bacteriology that classifies genera on the basis of their 16s RNA differences. Acetobacter spp as the main vinegar starters belong to family Acetobacteraceae that are gram negative obligate aerobes, chemoorganotrophic bacilli that are oxidase negative and oxidize ethanol to acetic acid. In this research we isolated and identified a native Acetobacter strain with high acetic acid productivity and tolerance against high ethanol concentrations from Iranian peach as a summer delicious fruit that is very susceptible to food spoilage and decay. We used selective and specific laboratorial culture media such as Standard GYC, Frateur and Carr medium. Also we used a new industrial culture medium and a miniature fermentor with a new aeration system innovated by Pars Yeema Biotechnologists Co., Isfahan Science and Technology Town (ISTT), Isfahan, Iran. The isolated strain was successfully cultivated in modified Carr media with 2.5% and 5% ethanol simultaneously in high temperatures, 34 - 40º C after 96 hours of incubation period. We showed that the increase of ethanol concentration resulted in rising of strain sensitivity to high temperature. In conclusion we isolated and characterized a new Acetobacter strain from Iranian peach that could be considered as a potential strain for production of a new vinegar type, peach vinegar, with a delicious taste and advantageous nutritional value in food biotechnology and industrial microbiology.
Abstract: The acidity of different raw Jordanian clays
containing zeolite, bentonite, red and white kaolinite and diatomite
was characterized by means of temperature programmed desorption
(TPD) of ammonia, conversion of 2-methyl-3-butyn-2-ol (MBOH),
FTIR and BET-measurements. FTIR spectra proved presence of
silanol and bridged hydroxyls on the clay surface. The number of
acidic sites was calculated from experimental TPD-profiles. We
observed the decrease of surface acidity correlates with the decrease
of Si/Al ratio except for diatomite. On the TPD-plot for zeolite two
maxima were registered due to different strength of surface acidic
sites. Values of MBOH conversion, product yields and selectivity
were calculated for the catalysis on Jordanian clays. We obtained that
all clay samples are able to convert MBOH into a major product
which is 3-methyl-3-buten-1-yne (MBYNE) catalyzed by acid
surface sites with the selectivity close to 70%. There was found a
correlation between MBOH conversion and acidity of clays
determined by TPD-NH3, i.e. the higher the acidity the higher the
conversion of MBOH. However, diatomite provided the lowest
conversion of MBOH as result of poor polarization of silanol groups.
Comparison of surface areas and conversions revealed the highest
density of active sites for red kaolinite and the lowest for zeolite and
diatomite.
Abstract: In wavelet regression, choosing threshold value is a crucial issue. A too large value cuts too many coefficients resulting in over smoothing. Conversely, a too small threshold value allows many coefficients to be included in reconstruction, giving a wiggly estimate which result in under smoothing. However, the proper choice of threshold can be considered as a careful balance of these principles. This paper gives a very brief introduction to some thresholding selection methods. These methods include: Universal, Sure, Ebays, Two fold cross validation and level dependent cross validation. A simulation study on a variety of sample sizes, test functions, signal-to-noise ratios is conducted to compare their numerical performances using three different noise structures. For Gaussian noise, EBayes outperforms in all cases for all used functions while Two fold cross validation provides the best results in the case of long tail noise. For large values of signal-to-noise ratios, level dependent cross validation works well under correlated noises case. As expected, increasing both sample size and level of signal to noise ratio, increases estimation efficiency.
Abstract: The aim of this paper is to compare the effectiveness and electrochemical behavior of typical oilfield corrosion inhibitors with previous oilfield corrosion inhibitors under the same electrochemical techniques to control preferential weld corrosion of X65 pipeline steel in artificial seawater saturated with carbon dioxide at a pressure of one bar. A secondary aim is to investigate the conditions under which current reversal takes place. A flow channel apparatus was used in the laboratory to simulate the actual condition that occurs in marine pipelines. Different samples from the parent metal, the weld metal and the heat affected zone in the pipeline steel were galvanically coupled. The galvanic currents flowing between the weld regions were recorded using zero-resistance ammeters and tested under static and flowing conditions in both inhibited and uninhibited media. The results show that a current reversal took place when 30ppm of both green oilfield inhibitors were present, resulting in accelerated weld corrosion.
Abstract: Due to the excess of a vehicle operation through its life, some elements may face failure and deteriorate with time. This leads us to carry out maintenance, repair, tune up or full overhaul. After a certain period, the vehicle elements deteriorations increase with time which causes a very high increase of doing the maintenance operations and their costs. However, the logic decision at this point is to replace the current vehicle by a new one with minimum failure and maximum income. The importance of studying vehicle replacement problems come from the increase of stopping days due to many deteriorations in the vehicle parts. These deteriorations increase year after year causing an increase of operating costs and decrease the vehicle income. Vehicle replacement aims to determine the optimum time to keep, maintain, overhaul, renew and replace vehicles. This leads to an improvement in vehicle income, total operating costs, maintenance cost, fuel and oil costs, ton-kilometers, vehicle and engine performance, vehicle noise, vibration, and pollution. The aim of this paper is to find the optimum replacement policies of Kuwait Passenger Transport Company (KPTCP) fleet of busses. The objective of these policies is to maximize the busses pure profits. The dynamic programming (D.P.) technique is used to generate the busses optimal replacement policies