An Autonomous Control
Methodology for Real-Time Traffic Injection Control
Hsiu-Jy Ho, Wei-Ming Lin
Abstract
When traffic
load approaches the capacity of a freeway, not only does the
expected delay for motorists exponentially increases but
also the overall throughput suffers
dramatically. Engineers have thus started employing
stoplights (ramp-meter) on access ramps to freeways in
highly congested areas to control the traffic injection into
the freeway in order to reduce the overall delay for the
motorists. The goal of this paper is to develop a
comprehensive Autonomous Real-time Traffic Injection Control
system (ARTIC) capable of minimizing the overall
delay for motorists according to the then traffic input load
and freeway congestion situation without replying on any
history data as all other known approaches do. We first
propose a general methodology that provides an autonomous
self-adjusting process to optimize performance for many
real-time resource-sharing applications, the Autonomous
Performance Optimizing Control Methodology (APOCoM).
This methodology which ARTIC is based on can be used
to automatically optimize performance of most
resource-sharing system in real time through periodical
self-adjustment of some system settings. Simulation results
show that the system employing the ARTIC thus
designed easily outperforms the system without using the
control approach. In one of the simulation for daily
twin-peak rush hours, about two fifth of congestion time (70
out of the original 167 minutes) is eliminated, and about
one third of travel time (9 out of the 27 minutes) is saved
per peak cycle.
Full Article
Some Issues Related
to Multi-Component Seismic Analysis of Steel Moment Frames
Alfredo Reyes-Salazar, Arturo López-Barraza, Luis A. López-López,
Juan I. Velázquez-Dimas
Abstract
Several
issues regarding multi-components seismic response analysis
of structures are addressed in this paper. The first issue
is related to the accuracy of the commonly used rules to
estimate the combined effect of the individual components of
earthquakes. The rules are studied for normal and principal
components, for local and global response parameters,
elastic and inelastic behavior and two and three components.
The critical orientation of the components is identified.
The second issue threats with the relative magnitude of the
effect of the vertical component with respect to those of
the horizontal components. Finally, the accuracy of
estimating the effect of the weaker horizontal component (RY)
as 85% of that of the stronger horizontal component (RX)
is studied. Results indicate that the total base shear is
reasonable estimated by the rules. However, they can
underestimate the combined response in terms of axial loads
for inelastic behavior. For the horizontal components the
SRSS rule is, in general, less conservative than the
30% rule. For the three components the 30% rule
is less conservative. It is concluded that if the
percentile rule is used to estimate the combined response a
value of 40% should be used instead of 30%. It is also
observed that the principal components give the maximum
response and that the ratio of the effect of the vertical
component to those of the horizontal components can be
significant and consequently should explicitly be used in
design. Values larger than unity are observed in some
cases. Results also indicate that the ratio of the effect
of the minor horizontal component to that of the major
horizontal component is much smaller that the typical
assumed value of 0.85. The value obtained in this study is
about 0.40.
Full
Article
An Explicit Expression for the Break-Even Radius of Insulation on a
Cylinder in Cross-Flow
Richard A. Davis
Abstract
An explicit expression was
developed for approximating the break-even radius of insulation on a
cylinder in cross flow with forced convective heat transfer where the
heat transfer rate equals the heat transfer rate from a bare cylinder.
Similar assumptions for the classical form of the critical radius of
insulation were invoked. However, the assumption that the heat
transfer coefficient is independent of the radius of insulation was
relaxed. The explicit expression derived here uses an algebraic
approximation for the logarithmic-mean radius of insulation to avoid the
computational inconvenience of solving the implicit nonlinear function
of the break-even radius of insulation that is sensitive to initial
guesses for the root. The results of the approximation agree with
the implicit expression within 1% and 5% for practical insulation
thicknesses up to 15 and 25 times the radius of the bare cylinder,
respectively. An analytical expression for the critical radius of
insulation where the convective heat transfer coefficient varies with
radius of insulation is also included.
Full Article
Idealized Plasma Problems for
Magnetohydrodynamic Code Verification
Pavlos G. Mikellides
Abstract
The closed-form analytic
solutions to two idealized plasma problems are presented as test cases
for verification and benchmarking of magnetohydrodynamic computer codes.
The first problem addresses magnetic diffusion with joule heating
designed to produce a diverging temperature profile so as to
significantly challenge the stability and accuracy limitations of
different numerical schemes. The second problem is the classic
magneto-shock tube problem for which an explicit analytic solution is
derived. This allows a simple and unique presentation of the solution
that can be easily utilized. A magnetohydrodynamic code is employed to
model the problems and comparisons of the numerical results serve as
bi-lateral validation of the analytic and numerical solutions.
Furthermore, these comparisons serve as a reference standard for
accuracy and overall code performance.
Full Article
Abstract
A novel model for
updating snowmelt estimates utilizing sparse, yet high quality snow
course survey (SCS) measurements for the purpose of improving long term
stream flow forecasts is presented. The paper provides details on the
development of the mathematical scheme of the model from first
principles of energy and mass balance of the snowpack. The development
methodology represents a successful attempt at the challenging task of
explicitly tying a complex daily highly nonlinear energy-budget snowmelt
function to the irregular SCS measurements. The updating scheme
facilitates the updating of sensitive snowmelt parameters that have a
long-term seasonal impact on snowmelt runoff. The updating model is
integrated within a river flow forecasting model, the UBC Watershed
Model, for the purpose of improving seasonal stream runoffs. Preliminary
application of the updating model shows significant improvements in both
the snowpack and stream flow forecasts.
Full Article
Abstract
Unlike mainstream
information visualization, ambient displays do not require active
attention, which makes existing information visualization design and
evaluation methodologies not readily applicable. In this paper, we
present a new evaluation methodology for ambient displays. The
methodology is then applied to a real-world case study, focusing on the
effectiveness, efficiency, comprehension and distraction performance of
four different visual cues for ambient displays. Our results show that
the effectiveness factor order in ambient displays is animation, color,
area and position. We also reveal how display-distraction influences the
comprehension of ambient displays, and discuss a relationship between
image change rate and data update rate. In addition, this paper proposes
a measurement of efficiency from cognitive science and a quantified
measurement of effectiveness in ambient displays. Finally, we propose
four guidelines for ambient display design.
Full Article
Performance and Emission Analysis of Bio Diesel Operated CI Engine
S.Sundarapandian and
G.Devaradjane
Abstract
A
theoretical model was developed to evaluate the performance
characteristics, combustion parameters and emissions of vegetable oil
esters like Jatropha, Mahua and Neem Oil esters. The predicted results
of these fuels are compared with Experimental result of diesel fuel.
From the results, it is found that the heat release and work done are
reduced by about 4% for Jatropha, 5% for Mahua and 8% for Neem oil
esters when compared to diesel. The harmful pollutants such as HC, CO,
NOX and smoke are reduced in the vegetable oil esters
compared to diesel fuel. From the investigation, it is concluded that
the performance of vegetable oil esters are good. Thus the developed
model is highly compatible for simulation work with bio diesel as an
alternative fuel.
Full Article
Abstract
A significant
drawback of Activities on Arcs (AOA) networks, is having
several different possible networks describing the same
project. In contrast, the Activities on Nodes (AON)
representation is unique. Having both AOA and AON networks
of a project is an advantage since some planning and
optimisation techniques strictly require AOA format while
others require AON format. While previous AOA research has
been focusing on minimizing the number of dummy arcs, this
paper focuses on generating a meaningful consistent network.
Each AOA node in the proposed technique is related to a
specific row in the immediate predecessors table: its
incoming arcs represent the immediate predecessors, and its
outgoing arcs represent the activity/ies possessing this set
of precedence constraints. The proposed algorithm generates
a unique AOA network from a list of precedence constraints.
While it does not minimize the number of dummy arcs the
efficiency in dummies is a by-product of this approach. Two
equivalent mathematical expressions are developed for the
number of generated AOA dummies of a given precedence table.
The paper also presents some linear formulations that could
be directly derived from an AOA net. The algorithm is
explained through a detailed example that starts with an
immediate predecessors table and ends with an AOA network.
Full
Article
Abstract
In the modern world of
electronic data and global communication information
displays can change quickly and so require constant
attention from users. However, the nature of the modern
world is also that users are often required to perform tasks
in parallel and there may be competition for the user's
attention. Ambient displays are information displays that
are designed to function at the periphery of a user's
attention. Unlike alarms, ambient displays should not
interrupt a user from their current task. Changes in the
display may, or may not be relevant to the user as the
display is usually designed to show non-critical data.
Because ambient displays are not critical to short term
tasks, it may be difficult to develop a business case for
using an ambient display. The questions that are most
difficult to quantify are: "How to design a good ambient
display?" and "When is an ambient display good?". This paper
addresses these two questions by describing our research
with a particular ambient display called;
"Butterfly/Dragonfly". This display is designed to show
stock market data and provide the user with short-term
market trends for a particular stock. The application domain
and implementation platform are described. The design of the
specific display is described in the context of "good"
design criteria. Finally a general framework for evaluating
ambient displays is introduced and the preliminary results
from an extended field trial are discussed.
Full
Article
A.
Kazmierczak
Abstract
A rectangular mesh is a rectangular array of processors. A
new algorithm is presented to recognize a rectangular mesh.
A program was written to determine if the new mesh
recognition algorithm mesh is valid. The program was
written in C and tested using a representation of a
network's nodes and their neighbors. The program tests
several meshes of different dimensions and different
mesh-like structures. The program found the meshes and
rejected the non-meshes on the test data. The algorithm
presented here is fairly simple and straightforward.
However, its true importance lies in the fact that it forms
the foundation for algorithms for recognition of more
complex mesh like structures, such as, ring mesh, torus,
spheroid, ellipsoid, and 3-dimensional mesh. Full
Article
Abstract
Three strategies to
produce optimal solutions in Disjunctive Logic Programming for the
well-known Bridge Crossing problem are described. These strategies are a
piggyback strategy, a non-piggyback strategy, and a mixed strategy. An
analysis to determine the number of actions required for an optimal
solution using these strategies is also given. Conditions under which a
particular strategy should be used to obtain an optimal solution are
formulated and proved. The strategies are implemented in the form of
optimization rules in a DLV program for the Bridge Crossing problem.
Preliminary results indicate a drastic reduction in execution time when
compared to other DLV programs for bridge crossing which do not
incorporate these strategies. The implementation uses a DLV Java
wrapper, which allows the embedding of disjunctive logic programs inside
an object-oriented environment.
Full Article
This paper introduces a
three-dimensional synchronized alternating Turing machine (3-SATM),
and investigates fundamental properties of 3-SATM0s
whose input tapes are restricted to cubic ones. The main topics of this
paper are: (1) a
relationship between the accepting powers of 3-SATM0s
and three-dimensional alternating Turing
machines with small space
bounds, (2) a relationship between the accepting powers of five-way and
six-way 3-SATM0s,
(3) a relationship between the accepting powers of 3-SATM0s
and three-dimensional nondeterministic
Turing machines
Full Article
Abstract
The increasing
importance of telecommunications for applications such as the internet
and video on demand leads to a requirement for a high bandwidth network
such as Asynchronous Transfer Mode (ATM). The design of an optimal ATM
network is a complex comprehensive task. Some of the problem domains are
the topology, connectivity and routing decisions. Given the complexity
of ATM design problem, computer based network design tools can be very
effective in solving such type of problem. The important aspect of
design tool is the usage of meta-heuristics as the optimization
algorithm. Large scale optimization problems comprise of many local
maxima and minima, moving out of local minima are very important to get
global
optima. ATM network
design being a large scale optimization problem simple heuristics alone
are not sufficient enough to solve the problem. This paper explores an
ATM network design tool based on Simulated Annealing (SA). A new
solution has been proposed based on SA that minimizes the cost of fiber
ducts and installs a minimum net present cost PON (Passive Optical
Network) ATM that satisfies the customer demand criterion. A
comprehensive ATM design tool has been proposed in which the backbone
network is connected using ring topology and the end-user connectivity
is provided using star topology.
Full Article
Comparison of hardware implementation and power consumption of low-power
multiple output linear feedback shift register linear feedback shift
register
Shilesh Malliyoor and Chao You
Abstract
A linear
feedback shift register has a variety of applications. Various low-power
architectures have been proposed. This paper compares two low-power
multiple output architectures in terms of the hardware implementation
and power consumption. A way to overcome the race around condition in
these architectures, which will improve the architecture, is proposed.
The polynomials are implemented by using 0.13 μm BiCMOS technology
provided by IBM. This paper will also show that the improved Katti’s
architecture, described in this paper is more power efficient than the
improved Lowy’s architecture. In specific applications, such as E0
stream cipher, the efficiency can be as high as 83% for certain
polynomials.
Full Article
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