Abstract: Estimating the reliability of a computer network has been a subject of great interest. It is a well known fact that this problem is NP-hard. In this paper we present a very efficient combinatorial approach for Monte Carlo reliability estimation of a network with unreliable nodes and unreliable edges. Its core is the computation of some network combinatorial invariants. These invariants, once computed, directly provide pure and simple framework for computation of network reliability. As a specific case of this approach we obtain tight lower and upper bounds for distributed network reliability (the so called residual connectedness reliability). We also present some simulation results.
Abstract: Multiple-input multiple-output (MIMO) systems are
widely in use to improve quality, reliability of wireless transmission
and increase the spectral efficiency. However in MIMO systems,
multiple copies of data are received after experiencing various
channel effects. The limitations on account of complexity due to
number of antennas in case of conventional decoding techniques have
been looked into. Accordingly we propose a modified sphere decoder
(MSD-1) algorithm with lower complexity and give rise to system
with high spectral efficiency. With the aim to increase signal
diversity we apply rotated quadrature amplitude modulation (QAM)
constellation in multi dimensional space. Finally, we propose a new
architecture involving space time trellis code (STTC) concatenated
with space time block code (STBC) using MSD-1 at the receiver for
improving system performance. The system gains have been verified
with channel state information (CSI) errors.
Abstract: One of the factors to maintain system survivability is
the adequate reactive power support to the system. Lack of reactive
power support may cause undesirable voltage decay leading to total
system instability. Thus, appropriate reactive power support scheme
should be arranged in order to maintain system stability. The strength
of a system capacity is normally denoted as system loadability. This
paper presents the enhancement of system loadability through
optimal reactive power planning technique using a newly developed
optimization technique, termed as Multiagent Immune Evolutionary
Programming (MAIEP). The concept of MAIEP is developed based
on the combination of Multiagent System (MAS), Artificial Immune
System (AIS) and Evolutionary Programming (EP). In realizing the
effectiveness of the proposed technique, validation is conducted on
the IEEE-26-Bus Reliability Test System. The results obtained from
pre-optimization and post-optimization process were compared
which eventually revealed the merit of MAIEP.
Abstract: The research on two-wheels balancing robot has
gained momentum due to their functionality and reliability when
completing certain tasks. This paper presents investigations into the
performance comparison of Linear Quadratic Regulator (LQR) and
PID-PID controllers for a highly nonlinear 2–wheels balancing robot.
The mathematical model of 2-wheels balancing robot that is highly
nonlinear is derived. The final model is then represented in statespace
form and the system suffers from mismatched condition. Two
system responses namely the robot position and robot angular
position are obtained. The performances of the LQR and PID-PID
controllers are examined in terms of input tracking and disturbances
rejection capability. Simulation results of the responses of the
nonlinear 2–wheels balancing robot are presented in time domain. A
comparative assessment of both control schemes to the system
performance is presented and discussed.
Abstract: A welded structure must be inspected to guarantee that the weld quality meets the design requirements to assure safety and reliability. However, X-ray image analyses and defect recognition with the computer vision techniques are very complex. Most difficulties lie in finding the small, irregular defects in poor contrast images which requires pre processing to image, extract, and classify features from strong background noise. This paper addresses the issue of designing methodology to extract defect from noisy background radiograph with image processing. Based on the use of actives contours this methodology seems to give good results
Abstract: Because of the great advance in multimedia
technology, digital multimedia is vulnerable to malicious
manipulations. In this paper, a public key self-recovery block-based
video authentication technique is proposed which can not only
precisely localize the alteration detection but also recover the missing
data with high reliability. In the proposed block-based technique,
multiple description coding MDC is used to generate two codes (two
descriptions) for each block. Although one block code (one
description) is enough to rebuild the altered block, the altered block
is rebuilt with better quality by the two block descriptions. So using
MDC increases the ratability of recovering data. A block signature is
computed using a cryptographic hash function and a doubly linked
chain is utilized to embed the block signature copies and the block
descriptions into the LSBs of distant blocks and the block itself. The
doubly linked chain scheme gives the proposed technique the
capability to thwart vector quantization attacks. In our proposed
technique , anyone can check the authenticity of a given video using
the public key. The experimental results show that the proposed
technique is reliable for detecting, localizing and recovering the
alterations.
Abstract: The public sector holds large amounts of data of
various areas such as social affairs, economy, or tourism. Various
initiatives such as Open Government Data or the EU Directive on
public sector information aim to make these data available for public
and private service providers. Requirements for the provision of
public sector data are defined by legal and organizational
frameworks. Surprisingly, the defined requirements hardly cover
security aspects such as integrity or authenticity.
In this paper we discuss the importance of these missing
requirements and present a concept to assure the integrity and
authenticity of provided data based on electronic signatures. We
show that our concept is perfectly suitable for the provisioning of
unaltered data. We also show that our concept can also be extended
to data that needs to be anonymized before provisioning by
incorporating redactable signatures. Our proposed concept enhances
trust and reliability of provided public sector data.
Abstract: In this paper sensitivity analysis is performed for
reliability evaluation of power systems. When examining the
reliability of a system, it is useful to recognize how results
change as component parameters are varied. This knowledge
helps engineers to understand the impact of poor data, and
gives insight on how reliability can be improved. For these
reasons, a sensitivity analysis can be performed. Finally, a real
network was used for testing the presented method.
Abstract: Today, design requirements are extending more and
more from electronic (analogue and digital) to multidiscipline design.
These current needs imply implementation of methodologies to make
the CAD product reliable in order to improve time to market, study
costs, reusability and reliability of the design process.
This paper proposes a high level design approach applied for the
characterization and the optimization of Switched-Current Sigma-
Delta Modulators. It uses the new hardware description language
VHDL-AMS to help the designers to optimize the characteristics of
the modulator at a high level with a considerably reduced CPU time
before passing to a transistor level characterization.
Abstract: It has been defined that the “network is the system".
This implies providing levels of service, reliability, predictability and
availability that are commensurate with or better than those that
individual computers provide today. To provide this requires
integrated network management for interconnected networks of
heterogeneous devices covering both the local campus. In this paper
we are addressing a framework to effectively deal with this issue. It
consists of components and interactions between them which are
required to perform the service fault management. A real-world
scenario is used to derive the requirements which have been applied
to the component identification. An analysis of existing frameworks
and approaches with respect to their applicability to the framework is
also carried out.
Abstract: When the failure function is monotone, some monotonic reliability methods are used to gratefully simplify and facilitate the reliability computations. However, these methods often work in a transformed iso-probabilistic space. To this end, a monotonic simulator or transformation is needed in order that the transformed failure function is still monotone. This note proves at first that the output distribution of failure function is invariant under the transformation. And then it presents some conditions under which the transformed function is still monotone in the newly obtained space. These concern the copulas and the dependence concepts. In many engineering applications, the Gaussian copulas are often used to approximate the real word copulas while the available information on the random variables is limited to the set of marginal distributions and the covariances. So this note catches an importance on the conditional monotonicity of the often used transformation from an independent random vector into a dependent random vector with Gaussian copulas.
Abstract: Use of a sliding joint is an effective method to
decrease the stress in foundation structure where there is a horizontal
deformation of subsoil (areas afflicted with underground mining) or
horizontal deformation of a foundation structure (pre-stressed
foundations, creep, shrinkage, temperature deformation). A
convenient material for a sliding joint is a bitumen asphalt belt.
Experiments for different types of bitumen belts were undertaken at
the Faculty of Civil Engineering - VSB Technical University of
Ostrava in 2008. This year an extension of the 2008 experiments is in
progress and the shear resistance of a slide joint is being tested as a
function of temperature in a temperature controlled room. In this
paper experimental results of temperature dependant shear resistance
are presented. The result of the experiments should be the sliding
joint shear resistance as a function of deformation velocity and
temperature. This relationship is used for numerical analysis of
stress/strain relation between foundation structure and subsoil. Using
a rheological slide joint could lead to a decrease of the reinforcement
amount, and contribute to higher reliability of foundation structure
and thus enable design of more durable and sustainable building
structures.
Abstract: As data to be stored in storage subsystems
tremendously increases, data protection techniques have become more
important than ever, to provide data availability and reliability. In this
paper, we present the file system-based data protection (WOWSnap)
that has been implemented using WORM (Write-Once-Read-Many)
scheme. In the WOWSnap, once WORM files have been created, only
the privileged read requests to them are allowed to protect data against
any intentional/accidental intrusions. Furthermore, all WORM files
are related to their protection cycle that is a time period during which
WORM files should securely be protected. Once their protection cycle
is expired, the WORM files are automatically moved to the
general-purpose data section without any user interference. This
prevents the WORM data section from being consumed by
unnecessary files. We evaluated the performance of WOWSnap on
Linux cluster.
Abstract: It is well known that metallic particles reduce the
reliability of Gas-Insulated Substation (GIS) equipments by initiating
partial discharge (PDs) that can lead to breakdown and complete
failure of GIS. This paper investigates the characteristics of PDs
caused by metallic particle adhering to the solid spacer. The PD
detection and measurement were carried out by using IEC 60270
method with particles of different sizes and at different positions on
the spacer surface. The results show that a particle of certain size at
certain position possesses a unique PD characteristic as compared to
those caused by particles of different sizes and/or at different
positions. Therefore PD characteristics may be useful for the particle
size and position identification.
Abstract: Adapting wireless devices to communicate within grid
networks empowers us by providing range of possibilities.. These
devices create a mechanism for consumers and publishers to create
modern networks with or without peer device utilization. Emerging
mobile networks creates new challenges in the areas of reliability,
security, and adaptability. In this paper, we propose a system
encompassing mobility management using AAA context transfer for
mobile grid networks. This system ultimately results in seamless task
processing and reduced packet loss, communication delays,
bandwidth, and errors.
Abstract: Genome profiling (GP), a genotype based technology, which exploits random PCR and temperature gradient gel electrophoresis, has been successful in identification/classification of organisms. In this technology, spiddos (Species identification dots) and PaSS (Pattern similarity score) were employed for measuring the closeness (or distance) between genomes. Based on the closeness (PaSS), we can buildup phylogenetic trees of the organisms. We noticed that the topology of the tree is rather robust against the experimental fluctuation conveyed by spiddos. This fact was confirmed quantitatively in this study by computer-simulation, providing the limit of the reliability of this highly powerful methodology. As a result, we could demonstrate the effectiveness of the GP approach for identification/classification of organisms.
Abstract: As we make progressive products for good works, and
future industries want to get higher speed and resolution from various
developments in the robotics as well as precise control system, the
concept of control feedback is getting more important. Within a range
of industrial developments, the concept is most responsible for the
high reliability of a device. We explain an efficient analyzing method
of a rotary encoder such as an incremental type encoder and absolute
type encoder using the LabVIEW program
Abstract: Unmanned aerial vehicles (UAVs) performing their
operations for a long time have been attracting much attention in
military and civil aviation industries for the past decade. The
applicable field of UAV is changing from the military purpose only to
the civil one. Because of their low operation cost, high reliability and
the necessity of various application areas, numerous development
programs have been initiated around the world. To obtain the optimal
solutions of the design variable (i.e., sectional airfoil profile, wing
taper ratio and sweep) for high performance of UAVs, both the lift and
lift-to-drag ratio are maximized whereas the pitching moment should
be minimized, simultaneously. It is found that the lift force and
lift-to-drag ratio are linearly dependent and a unique and dominant
solution are existed. However, a trade-off phenomenon is observed
between the lift-to-drag ratio and pitching moment. As the result of
optimization, sixty-five (65) non-dominated Pareto individuals at the
cutting edge of design spaces that are decided by airfoil shapes can be
obtained.
Abstract: In contrast to existing methods which do not take into account multiconnectivity in a broad sense of this term, we develop mathematical models and highly effective combination (BIEM and FDM) numerical methods of calculation of stationary and quasistationary temperature field of a profile part of a blade with convective cooling (from the point of view of realization on PC). The theoretical substantiation of these methods is proved by appropriate theorems. For it, converging quadrature processes have been developed and the estimations of errors in the terms of A.Ziqmound continuity modules have been received. For visualization of profiles are used: the method of the least squares with automatic conjecture, device spline, smooth replenishment and neural nets. Boundary conditions of heat exchange are determined from the solution of the corresponding integral equations and empirical relationships. The reliability of designed methods is proved by calculation and experimental investigations heat and hydraulic characteristics of the gas turbine first stage nozzle blade.
Abstract: This study attempts to validate the consumer-oriented
criteria list, developed by Wang et al. (2010), for selecting online
travel shopping sites. Based on a sample of 985 respondents,
confirmatory factor analysis was employed to test the factor structure
and assess the reliability and validity of the list. The results support the
list developed by Wang et al. (2010) and claim the list can be further
used to analyze, explain, and understand consumer behaviors about
online travel shopping.