Alfredo Reyes-Salazar,
Juan de Dios Garay-Morán, and Arturo López-Barraza
Abstract
The effectiveness of
energy dissipaters type friction on the reduction of the inelastic
seismic responses of moment steel frames (MSF) is studied. The energy
dissipater devices (EDD) are placed in the beamcolumn joints. The
parameters of the dissipaters are modified to vary the magnitude of the
friction force. The results of the study indicate that EDD based on
friction of metals can significantly reduce the seismic response of MSF.
The magnitude of the reduction, in terms of interstory displacements,
decreases with the fundamental period of the models used, but the
reduction for interstory shears is similar for all the models. Results
also indicate that many plastic hinges are formed in the frame without
energy dissipaters, but no plastic hinges are developed, in general, in
the frames with energy dissipaters. It indicates that using energy
dissipaters type friction protect the frames from significantly
yielding. It is shown that the equivalent viscous damping of energy
dissipaters type friction can be much larger than that existing in a
bare steel frame (x» 2%). Based on these findings, design response
spectra for MSF with energy dissipaters type friction can be developed
for specific sites by using appropriate amounts of equivalent viscous
damping.
Full Article
Abstract
System designers of today, in view of cutting more and more costs are
using integrated circuits, which are unique to their application. In the
present work, the main intention is to improve the density of
integration to a new height by integrating the Individual components of
a typical mobile system into a semi-custom VLSI solution. Further,
several error correction techniques are incorporated in the design to
get better error free, reliable and secured communication. It is
expected that the inclusion of one dimensional cellular automata
technique will bring attractive features in the present design and will
reduce error in communication thereby making it more reliable.
Full Article
A DDoS Defense Mechanism with Topology Reconfiguration
Yu Cai
Abstract
In this paper, we present design and implementation of a Secure
Collective Defense (SCOLD) system against DDoS attacks. The key idea of
SCOLD is to follow intrusion tolerance and topology reconfiguration
paradigm, and provide alternate routes via a set of proxy servers and
alternate gateways when normal route is unavailable or unstable due to
network failure, congestion, or DDoS attack. The BIND9 DNS server and
its DNS update utilities were enhanced to support new DNS entries with
indirect routing information. The indirect route was implemented by
utilizing IP Tunnel. Protocol software was developed on Linux systems.
Experimental results showed that SCOLD can improve network security,
availability and performance.
Full Article
A Rule-Based Fault Detection Algorithm for a Purge System of a
Ventricular Assist Device
Yih-Choung Yu
Abstract
A simple fault detection algorithm
was designed to monitor the purge pump operation of a rotary type
ventricular assist device (AB-180 Circulatory Support System [AB-180
CSS], CardiacAssist, Inc., Pittsburgh, PA, USA). This algorithm
receives the fluid pressure of the purge system, calculates the
pressure derivative, and then compares with the preset thresholds to
detect potential abnormal conditions, such as leaking and kinking
along the purge tubing, abnormal purge rate, and stoppage of the
purge pump. The thresholds were identified from bench top
experiments simulating the possible failure conditions in the purge
system. The algorithm was then implemented in a data acquisition
system and verified with different pumps and controllers. Because of
its simplicity, the algorithm only takes an
insignificant
computation time to process the measured signal. Therefore, it can be
incorporated into the existing controller without any major design
change in the controller hardware. The same concept is also applicable
as an alternative way to monitor an extremely low flow rate in other
devices in which directly monitoring flow rate from the devices is
important, but either too expensive or too difficult to implement.
Full Article
Real-time System Identification Techniques Based on Neural Networks
for a Low-cost UAV
Vishwas Puttige and Sreenatha Anavatti
Abstract
This paper describes system
identification techniques based on neural networks for a
nonlinear, Multi-Input Multi-Output (MIMO) system such as the Unmanned
Aerial Vehicle
(UAV). A novel training scheme for an online neural network model has
been tested and
implemented on the UAV and the results are presented. The online model
is compared
to a trained offline neural network model to bring out the merits and
demerits in both of
them. To improve the performance, the online and offline models are used
in combination
to form a multi-network architecture with a dynamic selection technique
to choose between
the outputs of each model based on a selection criterion. The neural
network models are
based on the autoregressive technique. The techniques have been
developed as a part of
the autonomous UAV program carried out at our research institution.
These identification
models can be developed for different stages of flight and their outputs
can be optimally
chosen to aid the control process. Each of the neural models have been
validated on a
Real-time Hardware In the Loop (HIL) simulation technique.
Full Article
Jahangir Dadkhah Chimeh, Mohammad Hakkak and Hamidreza Bakhshi
Abstract
Today wireless data
communication is growing rapidly. In particular, multimedia and
Internet communication by wireless systems are the most popular
services. Also, the architecture of wireless networks is varying to
provide such services better. In this paper, we review UTRAN (UMTS
Terrestrial Radio Access Network) focusing on the RLC (Radio Link
Control) sub-layer, its error recovery mechanisms and transport
channels when connected to Internet. Besides, we consider data flows
based on the acknowledgement mode RLC, the transparent mode MAC
and simulate the effects
of RLC protocol and erroneous MAC PDUs and delays, on the throughput.
Finally, we evaluate the throughput versus MAC PDU retransmission times
as well as the throughput efficiency versus MAC PDU retransmission times
and data block lengths.
Abstract
The Content Addressable
Memory (CAM) is a class of memory that allows access by data instead of
by physical address. On a read access to a CAM, embedded into a
processor cache, each word is compared in a broadcast mode, to see if it
matches the requested data; thus requiring only one access. Due to their
parallel pattern matching property, CAMs are gaining increasing
importance over Random Access Memory (RAM) in recent years, though
design complexity and power consumption continue to remain the major
drawbacks. The challenge in the design of a CAM cell is to reduce
leakage power in its compare circuitry without sacrificing the speed.
This paper describes a novel high-performance low power design of Serial
CAM
block
using Dual-Threshold CMOS (DTCMOS) technique, Transmission Gates (TG),
Transistor Stacks and an efficient Match Adaptive Architecture. In this
design, for high speed and low power operation, we have used four
separate, though not independent techniques. Replacing pass transistors
by TG, including transistor stacks in the compare circuitry and
assigning appropriate threshold voltages with dual threshold technique
have been found to reduce the Power Delay Product (PDP) of the basic
serial CAM cell by as much as up to 30%. Switching to a unique Match
Adaptive Architecture further improves this Power-Performance of the CAM
block significantly as compared to the conventional configuration.
Full
Article
An Efficient Algorithm for the Computation of Response-time Bounds for
CAN Messages
Imad Alzeer and Naji Qatanani
Abstract
This
paper presents an efficient computational exhaustive method that permits
to calculate both upper and lower response-time bounds for CAN messages.
Response-time analysis for CAN messages is relatively limited for
computations of the worst case situation. It is computed assuming a
maximum transmission time and critical instant releasing of messages in
the CAN system. This pessimism implies the maximum interference between
messages circulated on the bus. It may be correct from a hard real-time
perspective when synchronous releasing, but it doesn’t give good outlook
when non-common messages releasing. Hence to obtain an analysis close to
the reality, the investigated temporal constraints must take into
account both effects of time phasing and bit-stuffing. By using a
suitable data structure, our work introduces an elegant algorithm that
is able to deal with the previous effects. The obtained results for best
and worst cases response-times are different from previous results
obtained when assuming an optimist and a pessimist bit-stuffing length.
Full
Article
Solubility of Nitrous Oxide in Amine Aqueous Solutions
Basma
Yaghi and Omar Houache
Abstract
The
solubility of nitrous oxide (N2O) was measured in both pure water over
the temperature range (5-80)°C, and in amine aqueous solutions over the
temperature range (20-60)°C under atmospheric pressure. The systems
studied are monoethanolamine (MEA), diethanolamine (DEA), and
diisopropanolamine (DIPA) aqueous solutions. A new correlation was
developed for the solubility of N2O in water, while a semi-empirical
model of the excess Henry's constant was used to correlate the
solubility of N2O in amine solutions. The parameters of the correlation
were determined from the measured solubility data. Generally,
comparisons with experimental results from the reported literature
indicate that the obtained correlations are satisfactory for estimating
the solubility of N2O in amine solutions, which could be used to
estimate the free-gas solubility of CO2 in amines.
Full
Article
Theoretical Development and Applications of the MSPE Methodology in
Discrete and Stochastic Simulation Models Evolving in Replicated Runs
Lucia Cassettari, Simona Cipollina, Pietro Giribone,
Roberto Mosca, Roberto Revetria
Abstract
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