Abstract: Chloride induced corrosion of steel reinforcement is
the main cause of deterioration of reinforced concrete marine
structures. This paper investigates the relative performance of
alternative repair options with respect to the deterioration of
reinforced concrete bridge elements in marine environments. Focus is
placed on the initiation phase of reinforcement corrosion. A
laboratory study is described which involved exposing concrete
samples to accelerated chloride-ion ingress. The study examined the
relative efficiencies of two repair methods, namely Ordinary Portland
Cement (OPC) concrete and a concrete which utilised Ground
Granulated Blastfurnace Cement (GGBS) as a partial cement
replacement. The mix designs and materials utilised were identical to
those implemented in the repair of a marine bridge on the South East
coast of Ireland in 2007. The results of this testing regime serve to
inform input variables employed in probabilistic modelling of
deterioration for subsequent reliability based analysis to compare the
relative performance of the studied repair options.
Abstract: This paper describes the smart energy monitoring system with a wireless sensor network for monitoring of electrical usage in smart house. Proposed system is composed of wireless plugs and energy control wallpad server. The wireless plug integrates an AC power socket, a relay to switch the socket ON/OFF, a Hall effect sensor to sense current of load appliance and a Kmote. The Kmote is a wireless communication interface based on TinyOS. We evaluated wireless plug in a laboratory, analyzed and presented energy consumption data from electrical appliances for 3 months in home.
Abstract: This paper examines the use of mechanical aerator for
oxidation-ditch process. The rotor, which controls the aeration, is the
main component of the aeration process. Therefore, the objective of
this study is to find out the variations in overall oxygen transfer
coefficient (KLa) and aeration efficiency (AE) for different
configurations of aerator by varying the parameters viz. speed of
aerator, depth of immersion, blade tip angles so as to yield higher
values of KLa and AE. Six different configurations of aerator were
developed and fabricated in the laboratory and were tested for abovementioned
parameters. The curved blade rotor (CBR) emerged as a
potential aerator with blade tip angle of 47°.
The mathematical models are developed for predicting the
behaviour of CBR w.r.t kLa and power. In laboratory studies, the
optimum value of KLa and AE were observed to be 10.33 h-1 and
2.269 kg O2/ kWh.
Abstract: The results from experimental research of deformation
by upsetting and die forging of lead specimens wit controlled impact
are presented. Laboratory setup for conducting the investigations,
which uses cold rocket engine operated with compressed air, is
described. The results show that when using controlled impact is
achieving greater plastic deformation and consumes less impact
energy than at ordinary impact deformation process.
Abstract: The objective of this study is to investigate the effect of adding coal to obtain insulating ceramic product. The preparation of mixtures is achieved with 04 types of different masse compositions, consisting of gray and yellow clay, and coal. Analyses are performed on local raw materials by adding coal as additive. The coal content varies from 5 to 20 % in weight by varying the size of coal particles ranging from 0.25mm to 1.60mm.
Initially, each natural moisture content of a raw material has been determined at the temperature of 105°C in a laboratory oven. The Influence of low-coal content on absorption, the apparent density, the contraction and the resistance during compression have been evaluated. The experimental results showed that the optimized composition could be obtained by adding 10% by weight of coal leading thus to insulating ceramic products with water absorption, a density and resistance to compression of 9.40 %, 1.88 g/cm3, 35.46 MPa, respectively. The results show that coal, when mixed with traditional raw materials, offers the conditions to be used as an additive in the production of lightweight ceramic products.
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: The amount and heterogeneity of data in biomedical research, notably in interdisciplinary research, requires new methods for the collection, presentation and analysis of information. Important data from laboratory experiments as well as patient trials are available but come out of distributed resources. The Charite Medical School in Berlin has established together with the German Research Foundation (DFG) a new information service center for kidney diseases and transplantation (Open European Nephrology Science Centre - OpEN.SC). The system is based on a service-oriented architecture (SOA) with main and auxiliary modules arranged in four layers. To improve the reuse and efficient arrangement of the services the functionalities are described as business processes using the standardised Business Process Execution Language (BPEL).
Abstract: During the process of compaction in Hot-Mix Asphalt
(HMA) mixtures, the distance between aggregate particles decreases
as they come together and eliminate air-voids. By measuring the
inter-particle distances in a cut-section of a HMA sample the degree
of compaction can be estimated. For this, a calibration curve is
generated by computer simulation technique when the gradation and
asphalt content of the HMA mixture are known. A two-dimensional
cross section of HMA specimen was simulated using the mixture
design information (gradation, asphalt content and air-void content).
Nearest neighbor distance methods such as Delaunay triangulation
were used to study the changes in inter-particle distance and area
distribution during the process of compaction in HMA. Such
computer simulations would enable making several hundreds of
repetitions in a short period of time without the necessity to compact
and analyze laboratory specimens in order to obtain good statistics on
the parameters defined. The distributions for the statistical
parameters based on computer simulations showed similar trends as
those of laboratory specimens.
Abstract: In this paper a novel, simple and reliable digital firing
scheme has been implemented for speed control of three-phase
induction motor using ac voltage controller. The system consists of
three-phase supply connected to the three-phase induction motor via
three triacs and its control circuit. The ac voltage controller has three
modes of operation depending on the shape of supply current. The
performance of the induction motor differs in each mode where the
speed is directly proportional with firing angle in two modes and
inversely in the third one. So, the control system has to detect the
current mode of operation to choose the correct firing angle of triacs.
Three sensors are used to feed the line currents to control system to
detect the mode of operation. The control strategy is implemented
using a low cost Xilinx Spartan-3E field programmable gate array
(FPGA) device. Three PI-controllers are designed on FPGA to
control the system in the three-modes. Simulation of the system is
carried out using PSIM computer program. The simulation results
show stable operation for different loading conditions especially in
mode 2/3. The simulation results have been compared with the
experimental results from laboratory prototype.
Abstract: An electrical apparatus for measuring moisture
content was developed by our laboratory and uses dependence of
electrical properties on water content in studied material. Error
analysis of the apparatus was run by measuring different volumes of
water in a simplified specimen, i.e. hollow plexiglass block, in order
to avoid as many side-effects as possible. Obtained data were
processed using both basic and advanced statistics and results were
compared with each other. The influence of water content on
accuracy of measured data was studied as well as the influence of
variation of apparatus' proper arrangement or factual methodics of its
usage. The overall coefficient of variation was 4%. There was no
trend found in results of error dependence on water content.
Comparison with current surveys led to a conclusion, that the studied
apparatus can be used for indirect measurement of water content in
porous materials, with expectable error and under known conditions.
Factual experiments with porous materials are not involved, but are
currently under investigation.
Abstract: In this study three commercial semiconductor devices
were characterized in the laboratory for computed tomography
dosimetry: one photodiode and two phototransistors. It was evaluated
four responses to the irradiation: dose linearity, energy dependence,
angular dependence and loss of sensitivity after X ray exposure. The
results showed that the three devices have proportional response with
the air kerma; the energy dependence displayed for each device
suggests that some calibration factors would be applied for each one;
the angular dependence showed a similar pattern among the three
electronic components. In respect to the fourth parameter analyzed,
one phototransistor has the highest sensitivity however it also showed
the greatest loss of sensitivity with the accumulated dose. The
photodiode was the device with the smaller sensitivity to radiation,
on the other hand, the loss of sensitivity after irradiation is negligible.
Since high accuracy is a desired feature for a dosimeter, the
photodiode can be the most suitable of the three devices for
dosimetry in tomography. The phototransistors can also be used for
CT dosimetry, however it would be necessary a correction factor due
to loss of sensitivity with accumulated dose.
Abstract: In this work, the results of mixing study by a jet mixer in a tank have been investigated in the laboratory scale. The tank dimensions are H/D=1 and the jet entrance have been considered in
the center of upper surface of tank. RNG-k-ε model is used as the
turbulent model for the prediction of the pattern of turbulent flow
inside the tank. For this purpose, a tank with volume of 110 liter is
simulated and it has been divided into 410,000 tetrahedral control
cells for performing the calculations. The grids at the vicinity of the
nozzle and suction pare are finer to get more accurate results. The
experimental results showed that in a vertical jet, the lowest mixing
time takes place at 35 degree. In addition, mixing time decreased by
increasing the Reynolds number. Furthermore, the CFD simulation
predicted the items as well a flow patterns precisely that validates the
experiments.
Abstract: Insulation used in transformer is mostly oil pressboard insulation. Insulation failure is one of the major causes of catastrophic failure of transformers. It is established that partial discharges (PD) cause insulation degradation and premature failure of insulation. Online monitoring of PDs can reduce the risk of catastrophic failure of transformers. There are different techniques of partial discharge measurement like, electrical, optical, acoustic, opto-acoustic and ultra high frequency (UHF). Being non invasive and non interference prone, acoustic emission technique is advantageous for online PD measurement. Acoustic detection of p.d. is based on the retrieval and analysis of mechanical or pressure signals produced by partial discharges. Partial discharges are classified according to the origin of discharges. Their effects on insulation deterioration are different for different types. This paper reports experimental results and analysis for classification of partial discharges using acoustic emission signal of laboratory simulated partial discharges in oil pressboard insulation system using three different electrode systems. Acoustic emission signal produced by PD are detected by sensors mounted on the experimental tank surface, stored on an oscilloscope and fed to computer for further analysis. The measured AE signals are analyzed using discrete wavelet transform analysis and wavelet packet analysis. Energy distribution in different frequency bands of discrete wavelet decomposed signal and wavelet packet decomposed signal is calculated. These analyses show a distinct feature useful for PD classification. Wavelet packet analysis can sort out any misclassification arising out of DWT in most cases.
Abstract: The security of their network remains the priorities of almost all companies. Existing security systems have shown their limit; thus a new type of security systems was born: honeypots. Honeypots are defined as programs or intended servers which have to attract pirates to study theirs behaviours. It is in this context that the leurre.com project of gathering about twenty platforms was born. This article aims to specify a model of honeypots attack. Our model describes, on a given platform, the evolution of attacks according to theirs hours. Afterward, we show the most attacked services by the studies of attacks on the various ports. It is advisable to note that this article was elaborated within the framework of the research projects on honeyspots within the LABTIC (Laboratory of Information Technologies and Communication).
Abstract: Macrophomina phaseolina is a devastating soil-borne
fungal plant pathogen that causes charcoal rot disease in many
economically important crops worldwide. So far, no registered
fungicide is available against this plant pathogen. This study was
planned to examine the antifungal activity of an allelopathic grass
Cenchrus pennisetiformis (Hochst. & Steud.) Wipff. for the
management of M. phaseolina isolated from cowpea [Vigna
unguiculata (L.) Walp.] plants suffering from charcoal rot disease.
Different parts of the plants viz. inflorescence, shoot and root were
extracted in methanol. Laboratory bioassays were carried out using
different concentrations (0, 0.5, 1.0, …, 3.0 g mL-1) of methanolic
extracts of the test allelopathic grass species to assess the antifungal
activity against the pathogen. In general, extracts of all parts of the
grass exhibited antifungal activity. All the concentrations of
methanolic extracts of shoot and root significantly reduced fungal
biomass by 20–73% and 40–80%, respectively. Methanolic shoot
extract was fractionated using n-hexane, chloroform, ethyl acetate
and n-butanol. Different concentrations of these fractions (3.125,
6.25, …, 200 mg mL-1) were analyzed for their antifungal activity.
All the concentrations of n-hexane fraction significantly reduced
fungal biomass by 15–96% over corresponding control treatments.
Higher concentrations (12.5–200 mg mL-1) of chloroform, ethyl
acetate and n-butanol also reduced the fungal biomass significantly
by 29–100%, 46–100% and 24–100%, respectively.
Abstract: This paper made an attempt to investigate the problem associated with enhancement of emulsions of light crude oil-water recovery in an oil field of Algerian Sahara. Measurements were taken through experiments using RheoStress (RS600). Factors such as shear rate, temperature and light oil concentration on the viscosity behavior were considered. Experimental measurements were performed in terms of shear stress–shear rate, yield stress and flow index on mixture of light crude oil–water. The rheological behavior of emulsion showed Non-Newtonian shear thinning behavior (Herschel-Bulkley). The experiments done in the laboratory showed the stability of some water in light crude oil emulsions form during consolidate oil recovery process. To break the emulsion using additives may involve higher cost and could be very expensive. Therefore, further research should be directed to find solution of these problems that have been encountered.
Abstract: The cables in a nuclear power plant are designed to be
used for about 40 years in safe operation environment. However, the
heat and radiation in the nuclear power plant causes the rapid
performance deterioration of cables in nuclear vessels and heat
exchangers, which requires cable lifetime estimation. The most
accurate method of estimating the cable lifetime is to evaluate the
cables in a laboratory. However, removing cables while the plant is
operating is not allowed because of its safety and cost. In this paper, a
robot system to estimate the cable lifetime in nuclear power plants is
developed and tested. The developed robot system can calculate a
modulus value to estimate the cable lifetime even when the nuclear
power plant is in operation.
Abstract: The article presents test results on the changes
occurring in sewage sludge during the process of its storage. Tests
were conducted on mechanically dehydrated sewage sludge derived
from large municipal sewage treatment plants equipped with
biological sewage treatment systems. In testing presented in the paper
the focus was on the basic fuel properties of sewage sludge: moisture
content, heat of combustion, carbon share. In the first part of the
article the overview of the issues concerning the sewage sludge
management is presented and the genesis of tests is explained.
Further in the paper, selected results of conducted tests are discussed.
Changes in tested parameters were determined in the period of a 10-
month sewage storage.
Abstract: A Laboratory-scale packed bed reactor with microbial
cellulose as the biofilm carrier was used to investigate the
denitrification of high-strength nitrate wastewater with specific
emphasis on the effect the nitrogen loading rate and hydraulic
retention time. Ethanol was added as a carbon source for
denitrification. As a result of this investigation, it was found that up
to 500 mg/l feed nitrate concentration the present system is able to
produce an effluent with nitrate content below 10 ppm at 3 h
hydraulic retention time. The highest observed denitrification rate
was 4.57 kg NO3-N/ (m3 .d) at a nitrate load of 5.64 kg NO3-
N/(m3 .d), and removal efficiencies higher than 90% were obtained
for loads up to 4.2 kg NO3-N/(m3 .d). A mass relation between COD
consumed and NO3-N removed around 2.82 was observed. This
continuous-flow bioreactor proved an efficient denitrification system
with a relatively low retention time.
Abstract: In this study, we sought to investigate the mercury
removal efficiency of manganese oxides from natural gas. The
fundamental studies on mercury removal with manganese oxides
sorbents were carried out in a laboratory scale fixed bed reactor at 30
°C with a mixture of methane (20%) and nitrogen gas laden with 4.8
ppb of elemental mercury. Manganese oxides with varying surface
area and crystalline phase were prepared by conventional precipitation
method in this study. The effects of surface area, crystallinity and
other metal oxides on mercury removal efficiency were investigated.
Effect of Ag impregnation on mercury removal efficiency was also
investigated. Ag supported on metal oxide such titania and zirconia as
reference materials were also used in this study for comparison. The
characteristics of mercury removal reaction with manganese oxide
was investigated using a temperature programmed desorption (TPD)
technique.
Manganese oxides showed very high Hg removal activity (about
73-93% Hg removal) for first time use. Surface area of the manganese
oxide samples decreased after heat-treatment and resulted in complete
loss of Hg removal ability for repeated use after Hg desorption in the
case of amorphous MnO2, and 75% loss of the initial Hg removal
activity for the crystalline MnO2. Mercury desorption efficiency of
crystalline MnO2 was very low (37%) for first time use and high (98%)
after second time use. Residual potassium content in MnO2 may have
some effect on the thermal stability of the adsorbed Hg species.
Desorption of Hg from manganese oxides occurs at much higher
temperatures (with a peak at 400 °C) than Ag/TiO2 or Ag/ZrO2.
Mercury may be captured on manganese oxides in the form of mercury
manganese oxide.