Abstract: This paper describes a method to measure and
compensate a 4 axes ultra-precision machine tool that generates micro
patterns on the large surfaces. The grooving machine is usually used
for making a micro mold for many electrical parts such as a light guide
plate for LCD and fuel cells. The ultra precision machine tool has three
linear axes and one rotational table. Shaping is usually used to
generate micro patterns. In the case of 50 μm pitch and 25 μm height
pyramid pattern machining with a 90° wedge angle bite, one of linear
axis is used for long stroke motion for high cutting speed and other
linear axis are used for feeding. The triangular patterns can be
generated with many times of long stroke of one axis. Then 90°
rotation of work piece is needed to make pyramid patterns with
superposition of machined two triangular patterns.
To make a two dimensional positioning error, straightness of two
axes in out of plane, squareness between the each axis are important.
Positioning errors, straightness and squarness were measured by laser
interferometer system. Those were compensated and confirmed by
ISO230-6. One of difficult problem to measure the error motions is
squareness or parallelism of axis between the rotational table and
linear axis. It was investigated by simultaneous moving of rotary table
and XY axes. This compensation method is introduced in this paper.
Abstract: The mixed oxide nuclear fuel (MOX) of U and Pu contains several percent of fission products and minor actinides, such as neptunium, americium and curium. It is important to determine accurately the decay heat from Curium isotopes as they contribute significantly in the MOX fuel. This heat generation can cause samples to melt very quickly if excessive quantities of curium are present. In the present paper, we introduce a new approach that can predict the decay heat from curium isotopes. This work is a part of the project funded by King Abdulaziz City of Science and Technology (KASCT), Long-Term Comprehensive National Plan for Science, Technology and Innovations, and take place in King Abdulaziz University (KAU), Saudi Arabia. The approach is based on the numerical solution of coupled linear differential equations that describe decays and buildups of many nuclides to calculate the decay heat produced after shutdown. Results show the consistency and reliability of the approach applied.
Abstract: In this paper dynamics of a vapour bubble generated
due to a local energy input inside a vertical rigid cylinder and in the
absence of buoyancy forces is investigated. Different ratios of the
diameter of the rigid cylinder to the maximum radius of the bubble
are considered. The Boundary Integral Equation Method is employed
for numerical simulation of the problem. Results show that during
the collapse phase of the bubble inside a vertical rigid cylinder, two
liquid micro jets are developed on the top and bottom sides of the
vapour bubble and are directed inward. Results also show that
existence of a deposit rib inside the vertical rigid cylinder slightly
increases the life time of the bubble. It is found that by increasing the
ratio of the cylinder diameter to the maximum radius of the bubble,
the rate of the growth and collapse phases of the bubble increases
and the life time of the bubble decreases.
Abstract: Memory Errors Detection and Correction aim to secure the transaction of data between the central processing unit of a satellite onboard computer and its local memory. In this paper, the application of a double-bit error detection and correction method is described and implemented in Field Programmable Gate Array (FPGA) technology. The performance of the proposed EDAC method is measured and compared with two different EDAC devices, using the same FPGA technology. Statistical analysis of single-event upset (SEU) and multiple-bit upset (MBU) activity in commercial memories onboard the first Algerian microsatellite Alsat-1 is given.
Abstract: Subgrade moisture content varies with environmental and soil conditions and has significant influence on pavement performance. Therefore, it is important to establish realistic estimates of expected subgrade moisture contents to account for the effects of this variable on predicted pavement performance during the design stage properly. The initial boundary soil suction profile for a given pavement is a critical factor in determining expected moisture variations in the subgrade for given pavement and climatic and soil conditions. Several numerical models have been developed for predicting water and solute transport in saturated and unsaturated subgrade soils. Soil hydraulic properties are required for quantitatively describing water and chemical transport processes in soils by the numerical models. The required hydraulic properties are hydraulic conductivity, water diffusivity, and specific water capacity. The objective of this paper was to determine isothermal moisture profiles in a soil fill and predict the soil moisture movement above the ground water table using a simple one-dimensional finite difference model.
Abstract: This article concerns the presentation of an integrated
method for detection of steganographic content embedded by new
unknown programs. The method is based on data mining and
aggregated hypothesis testing. The article contains the theoretical
basics used to deploy the proposed detection system and the
description of improvement proposed for the basic system idea.
Further main results of experiments and implementation details are
collected and described. Finally example results of the tests are
presented.
Abstract: The recent drive for use of performance-based methodologies in design and assessment of structures in seismic areas has significantly increased the demand for the development of reliable nonlinear inelastic static pushover analysis tools. As a result, the adaptive pushover methods have been developed during the last decade, which unlike their conventional pushover counterparts, feature the ability to account for the effect that higher modes of vibration and progressive stiffness degradation might have on the distribution of seismic storey forces. Even in advanced pushover methods, little attention has been paid to the Unsymmetric structures. This study evaluates the seismic demands for three dimensional Unsymmetric-Plan buildings determined by the Displacement-based Adaptive Pushover (DAP) analysis, which has been introduced by Antoniou and Pinho [2004]. The capability of DAP procedure in capturing the torsional effects due to the irregularities of the structures, is investigated by comparing its estimates to the exact results, obtained from Incremental Dynamic Analysis (IDA). Also the capability of the procedure in prediction the seismic behaviour of the structure is discussed.
Abstract: The amplitude response of infrared (IR) sensors
depends on the reflectance properties of the target. Therefore, in
order to use IR sensor for measuring distances accurately, prior
knowledge of the surface must be known. This paper describes the
Phong Illumination Model for determining the properties of a surface
and subsequently calculating the distance to the surface. The angular
position of the IR sensor is computed as normal to the surface for
simplifying the calculation. Ultrasonic (US) sensor can provide the
initial information on distance to obtain the parameters for this
method. In addition, the experimental results obtained by using
LabView are discussed. More care should be taken when placing the
objects from the sensors during acquiring data since the small change
in angle could show very different distance than the actual one.
Since stereo camera vision systems do not perform well under some
environmental conditions such as plain wall, glass surfaces, or poor
lighting conditions, the IR and US sensors can be used additionally to
improve the overall vision systems of mobile robots.
Abstract: One approach to assess neural networks underlying the cognitive processes is to study Electroencephalography (EEG). It is relevant to detect various mental states and characterize the physiological changes that help to discriminate two situations. That is why an EEG (amplitude, synchrony) classification procedure is described, validated. The two situations are "eyes closed" and "eyes opened" in order to study the "alpha blocking response" phenomenon in the occipital area. The good classification rate between the two situations is 92.1 % (SD = 3.5%) The spatial distribution of a part of amplitude features that helps to discriminate the two situations are located in the occipital regions that permit to validate the localization method. Moreover amplitude features in frontal areas, "short distant" synchrony in frontal areas and "long distant" synchrony between frontal and occipital area also help to discriminate between the two situations. This procedure will be used for mental fatigue detection.
Abstract: Children with hemiplgic cerebral palsy often walk
with diminished reciprocal arm swing so the purpose of this study
was to describe kinematic characteristics in children with hemiplegic
cerebral palsy (CP) during the gait suphases, and find if there is a
correlation between upper(shoulder and elbow) and lower(hip, knee,
and ankle) limb joints either in involved or uninvolved.48 children
with hemiplegic cerebral palsy (18boys, 30girls) with an average age
of (5.1±0.87) years were selected randomly to evaluate joint angles
during gait by 3D motion analysis system with 6 pro reflex cameras
in a sagittal plane for both sides of the body. The results showed
increased shoulder and elbow flexion, increased hip angular
displacement, decreased knee and ankle arcs during gait cycle, also
there is correlation between shoulder and elbow to hip, knee, and
ankle joints during various subphases of gait.
Abstract: This paper presents a ray tracing simulation technique for characterize the radiowave propagation inside building. The implementation of an algorithm capable of enumerating a large number of propagation paths in interactive time for the special case of 2.5D. The effective dielectric constants of the building structure in the simulations are indicated. The study describes an efficient 2.5D model of ray tracing algorithm were compared with 3D model. The result of the first investigations is that the environment of the indoor wave significantly changes as we change the electric parameters of material constructions. A detailed analysis of the dependence of the indoor wave on the wideband characteristics of the channel: root mean square (RMS) delay spread characteristics and Mean excess delay, is also investigated.
Abstract: In this paper a three dimensional thermal model of a
sliding contact system is proposed for both steady-state or transient
conditions. The influence of contact force, electric current and
ambient temperature on the temperature distribution, has been
investigated. A thermal analysis of the different type of the graphite
material of fixed electric contact and its influence on contact system
temperature rise, has been performed. To validate the three
dimensional thermal model, some experimental tests have been done.
There is a good correlation between experimental and simulation
results.
Abstract: Virtually all existing networked system management
tools use a Manager/Agent paradigm. That is, distributed agents are
deployed on managed devices to collect local information and report
it back to some management unit. Even those that use standard
protocols such as SNMP fall into this model. Using standard protocol
has the advantage of interoperability among devices from different
vendors. However, it may not be able to provide customized
information that is of interest to satisfy specific management needs.
In this dissertation work, different approaches are used to
collect information regarding the devices attached to a Local Area
Network. An SNMP aware application is being developed that will
manage the discovery procedure and will be used as data collector.
Abstract: This paper present some preliminary work on the
preparation and physicochemical caracterization of nanocomposite
MFI-alumina structures based on alumina hollow fibres. The fibers
are manufactured by a wet spinning process. α-alumina particles were
dispersed in a solution of polysulfone in NMP. The resulting slurry is
pressed through the annular gap of a spinneret into a precipitation
bath. The resulting green fibres are sintered. The mechanical strength
of the alumina hollow fibres is determined by a three-point-bending
test while the pore size is characterized by bubble-point testing. The
bending strength is in the range of 110 MPa while the average pore
size is 450 nm for an internal diameter of 1 mm and external diameter
of 1.7 mm. To characterize the MFI membranes various techniques
were used for physicochemical characterization of MFI–ceramic
hollow fibres membranes: The nitrogen adsorption, X-ray
diffractometry, scanning electron microscopy combined with X
emission microanalysis. Scanning Electron Microscopy (SEM) and
Energy Dispersive Microanalysis by the X-ray were used to observe
the morphology of the hollow fibre membranes (thickness,
infiltration into the carrier, defects, homogeneity). No surface film,
has been obtained, as observed by SEM and EDX analysis and
confirmed by high temperature variation of N2 and CO2 gas
permeances before cation exchange. Local analysis and characterise
(SEM and EDX) and overall (by ICP elemental analysis) were
conducted on two samples exchanged to determine the quantity and
distribution of the cation of cesium on the cross section fibre of the
zeolite between the cavities.
Abstract: It is very important to determine reference temperature when convective temperature because it should be used to calculate the temperature potential. This paper deals with the development of a new method that can determine heat transfer coefficient and reference free stream temperature simultaneously, based on transient heat transfer experiments with using two narrow band thermo-tropic liquid crystals (TLC's). The method is validated through error analysis in terms of the random uncertainties in the measured temperatures. It is shown how the uncertainties in heat transfer coefficient and free stream temperature can be reduced. The general method described in this paper is applicable to many heat transfer models with unknown free stream temperature.
Abstract: Achieving success is a highly critical issue for the
companies to survive in a competitive business environment. The
construction industry is also an area where there is strong
competition due to a large number of construction contractors. There
have been many factors such as qualified employees, quality
workmanship and financial management that can lead to company
success in the construction industry. The aim of this study was to
investigate the critical factors leading to construction company
success. Within this context, a survey was carried out among 40
Turkish construction companies which are located in the Northwest
region of Turkey. In this survey, top-level managers and owners of
the companies were interviewed. The interviews took place over a
five month period between January and May 2007. Finally, the
ranking of the critical success factors has been determined by using
the Simple Multi Attribute Rating Technique (SMART). Based on
the results, business management, financial conditions and
owner/manager characteristics were determined as the most
important factors to company success.
Abstract: The use of wind energy for electricity generation is
growing rapidly across the world and in Portugal. However, the
geographical characteristics of the country along with the average
wind regime and with the environmental restrictions imposed to these
projects create limitations to the exploit of the onshore wind
resource. The best onshore wind spots are already committed and the
possibility of offshore wind farms in the Portuguese cost is now
being considered. This paper aims to make a contribution to the
evaluation of offshore wind power projects in Portugal. The technical
restrictions are addressed and the strategic, environmental and
financial interest of the project is analysed from the private company
and public points of view. The results suggest that additional support
schemes are required to ensure private investors interest for these
projects. Assuming an approach of direct substitution of energy
sources for electricity generation, the avoided CO2 equivalent
emissions for an offshore wind power project were quantified. Based
on the conclusions, future research is proposed to address the
environmental and social impacts of these projects.
Abstract: In this paper, we first give the representation of the general solution of the following inverse eigenvalue problem (IEP): Given X ∈ Rn×p and a diagonal matrix Λ ∈ Rp×p, find nontrivial real-valued symmetric arrow-head matrices A and B such that AXΛ = BX. We then consider an optimal approximation problem: Given real-valued symmetric arrow-head matrices A, ˜ B˜ ∈ Rn×n, find (A, ˆ Bˆ) ∈ SE such that Aˆ − A˜2 + Bˆ − B˜2 = min(A,B)∈SE (A−A˜2 +B −B˜2), where SE is the solution set of IEP. We show that the optimal approximation solution (A, ˆ Bˆ) is unique and derive an explicit formula for it.
Abstract: Dengue fever has become a major concern for health
authorities all over the world particularly in the tropical countries.
These countries, in particular are experiencing the most worrying
outbreak of dengue fever (DF) and dengue haemorrhagic fever
(DHF). The DF and DHF epidemics, thus, have become the main
causes of hospital admissions and deaths in Malaysia. This paper,
therefore, attempts to examine the environmental factors that may
influence the recent dengue outbreak. The aim of this study is twofold,
firstly is to establish a statistical model to describe the
relationship between the number of dengue cases and a range of
explanatory variables and secondly, to identify the lag operator for
explanatory variables which affect the dengue incidence the most.
The explanatory variables involved include the level of cloud cover,
percentage of relative humidity, amount of rainfall, maximum
temperature, minimum temperature and wind speed. The Poisson and
Negative Binomial regression analyses were used in this study. The
results of the analyses on the 915 observations (daily data taken from
July 2006 to Dec 2008), reveal that the climatic factors comprising of
daily temperature and wind speed were found to significantly
influence the incidence of dengue fever after 2 and 3 weeks of their
occurrences. The effect of humidity, on the other hand, appears to be
significant only after 2 weeks.