Abstract
〈Vol.3 No.6(2010.11)〉
Titles
[Contributed Papers]
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■ Study on Efficiency of Evacuation with an Obstacle on Hexagonal Cell
Space
The Univ. of Tokyo/JSPS・Daichi YANAGISAWA, Ryosuke NISHI,
Meiji Univ.・Akiyasu TOMOEDA,
The Univ. of Tokyo・Kazumichi OHTSUKA,
Mitsubishi Research Institute, Inc.・Ayako KIMURA,
The Univ. of Tokyo・Yushi SUMA,
and The Univ. of Tokyo/JST・Katsuhiro NISHINARI
We have found that putting an obstacle in front of an exit in a congested situation increases the pedestrian outflow, which is the number of pedestrians going through an exit with unit width in unit time, from our experiments. In this paper, the effects of conflicts and turning, which affect the pedestrian outflow significantly, are introduced by the frictional and turning functions to analyze the effect of an obstacle. They clearly explain the mechanism of the effect of an obstacle, i.e., it blocks a pedestrian moving to the exit and decreases the average number of pedestrians involved in the conflict. We have also studied when an obstacle contributes to ease the congestion most effectively. The results of our simulation indicate that its maximum efficacy is achieved at the point where the cluster of pedestrians is started to form. Mean traveling time of pedestrians becomes a quarter if an obstacle is set up since it prevents the formation of the cluster against increase of the inflow by reducing the impact of conflicts.
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■ A Method for Determining the Timing of Displaying the Speaker's Face
and Captions for a Real-Time Speech-to-Caption System
Tsukuba Univ. of Tech.・Hayato KUROKI,
AIST・Shuichi INO,
The Univ. of Tokyo・Satoko NAKANO, B.U.G., Inc.・Kotaro HORI,
and The Univ. of Tokyo・Tohru IFUKUBE
We have been studying a real-time speech-to-caption system using speech
recognition technology with a “repeat-speaking” method. In this system,
we used a “repeat-speaker” who listens to a lecturer’s voice and then
speaks back the lecturer’s speech utterances into a speech recognition
computer. Our througoing system showed that the accuracy of the captions
is about 97% in Japanese-Japanese conversion and the conversion time from
voices to captions is about 4 seconds in English-English conversion in
some international conferences. Of course it required a lot of costs to
achieve these high performances. In human communications, speech understanding
depends not only on verbal information but also on non-verbal information
such as speaker’s gestures, and face and mouth movements. So we found
the idea to display information of captions and speaker’s face movement
images with a suitable way to achieve a higher comprehension after storing
information once into a computer briefly. In this paper, we investigate
the relationship of the display sequence and display timing between captions
that have speech recognition errors and the speaker’s face movement images.
The results show that the sequence “to display the caption before the
speaker’s face image” improves the comprehension of the captions. The
sequence “to display both simultaneously” shows an improvement only a
few percent higher than the question sentence, and the sequence “to display
the speaker’s face image before the caption” shows almost no change.
In addition, the sequence “to display the caption 1 second before the
speaker’s face shows the most significant improvement of all the conditions.
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■ Local State Transition of Feedback Controlled Quantum Systems with Imperfect
Detector Efficiency - Part I:Differential Geometric Analysis for Dynamical
Systems with Matrix-Valued States -
The Univ. of Tokyo・Tomotake SASAKI, Shinji HARA, and Koji TSUMURA
We consider a new class of dynamical systems whose state is represented by a Hermitian matrix motivated by treating quantum control problems. We develop theory and techniques of differential geometric analysis for dynamical systems in that class, where Lie product of matrix functions is introduced and plays an important role. We provide a simple and coordinate-free calculation method for the Lie product of matrix
functions which enables efficient differential geometric analysis. The result of this paper will be used in the follow-up paper on analysis of local state transition of controlled quantum systems under continuous quantum measurement with imperfect detector efficiency.
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■ Local State Transition of Feedback Controlled Quantum Systems with Imperfect
Detector Efficiency - Part II:Accessibility Analysis for Quantum Systems-
The Univ. of Tokyo・Tomotake SASAKI, Shinji HARA, and Koji TSUMURA
In this paper, we analyze local state transition of the controlled quantum system under continuous quantum measurement, which is described by a matrix-valued nonlinear stochastic differential equation. To this end, we utilize the method of differential geometric analysis for systems with matrix-valued states developed in the first part of this series. The method provides us a direct and efficient way of analysis with a clear perspective. We study local state transition of the controlled quantum systems with imperfect detector efficiency which has not been studied enough in previous works. The controlled quantum system with perfect detector efficiency is also investigated as a special case. Sufficient conditions for the measurement operator and the control Hamiltonian are derived, under which the local state transition is quite limited. We also show that the conditions are satisfied in many typical situations. The results reveal fundamental nature of the controlled quantum systems under continuous quantum measurement.
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■ Stability Analysis and Stabilization of Nonlinear Systems via Locally
Defined Density Functions
Hiroshima Univ.・Izumi MASUBUCHI
This paper considers local stability analysis of nonlinear systems with
deriving a positively invariant set based on Rantzer's stability theory
by using density functions. We define notion of locally defined density
functions around an equilibrium that give monotonously increasing positive
measures near the equilibrium of a nonlinear system. Under several assumptions,
it is shown that some level set of a locally defined density function is
a positively invariant set where almost all of the system trajectories
converge to the equilibrium. We also mention an SOS (sum-of-squares) formulation
for synthesis of a nonlinear gain via locally defined density functions.
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■ Airborne GPS Reflectometry from Low Altitude Aircraft
Tokyo Univ. of Marine Science and Tech.・Takuji EBINUMA and Akio YASUDA
This work is intended to develop a software-defined Global Positioning System (GPS) receiver specifically designed to process reflected GPS signal off the ground or the ocean surface for the purpose of remote sensing. A set of airborne campaign was conducted to evaluate the performance of the prototype GPS reflectometry receiver. The reflected signal was tracked in an open-loop manner using the so called delay mapping receiver. The result shows that the prototype receiver is capable of providing altimetric measurements within a few meter.
▲ ■ Automobile Optimal Driving Control using Surrounding Information based
on Model Prediction Control
Waseda Univ.・Dongmei WU,
Fuji Electric FA Components & Systems Co.・Yang XIA,
Waseda Univ.・Masatoshi OGAWA, Harutoshi OGAI,
and Kyushu Univ.・Taketoshi KAWABE
In this paper, an optimal driving control system based on model predictive control (MPC) is developed, for the purpose of processing more surrounding information which is essential for improving the
current intelligent driving assistance and further dealing with traffic
issues caused by automobiles. The proposed system provides a method of
calculating a desirable driving path based on surrounding traffic environments.
The performance of this system is evaluated through simulations which are
carried out with introduction of surrounding information such as traffic
jam, traffic signal change,and fuel consumption. Simulation results reveal
that the proposed system as a driving assist system has a potential of
finding optimal driving paths for drivers.
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■ Integrated Backstepping Mobile Robot Controller Design by Applying Sum
of Squares Approach
National Cheng-Kung Univ.・Shung-Hung CHEN and Jyh-Ching JUANG
The paper presents a sum of squares (SOS) based backstepping control design
method for a three wheels omni-directional mobile robot. The characteristic
of the strict-feedback system associated with mobile robots is considered
to construct the backstepping controller. To account for the saturation
problem in the mobile robot, the SOS conditions are developed based on
the backstepping controller framework to achieve stability and enlarge
the guaranteed region of convergence. Computer simulations for mobile robots
demonstrate the effectiveness of the proposed SOS-based backstepping controller
design method.
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■ I-PD Flight Controller Design based on Integral-type Optimal Servomechanism
National Defense Academy・Hiroyuki KONDO and Yoshimasa OCHI
This paper describes a design method of an I-PD (proportional-derivative
preceded integral) controller for a single-input-single-output plant. The
proposed method, which is relatively simple compared with the conventional
methods, consists of two stages: First, a second-order model is determined
by applying the balanced truncation to the closed-loop system for a given
higher-order plant, and then, an output and error signal feedback controller
based on integral-type optimal servomechanism is designed for the second-order
model. The resultant controller gives as sufficient stability margins and
good control performance as an observer-based state feedback controller.
Design examples are presented to demonstrate the effectiveness and usefulness
of the proposed method.
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■ On Sensitivity Reduction Problems of Sampled-Data Systems - Relationships to the Problems of Discrete-Time Systems -
Osaka Univ.・Yoshimichi ITO, Hiroshi SHIRAHAMA,
and Kyoto Univ.・Tomomichi HAGIWARA
This paper is concerned with the sensitivity reduction (SR) and complementary
sensitivity reduction (CSR) problems of sampled-data systems. We begin
our study by showing that, given a sampled-data system Σ, the H∞ norms
of the sensitivity and complementary sensitivity of Σ can be expressed
as those for an equivalent discrete-time system Σ DSP called the doubly
sensitivity-preserving discretized system. We also consider the conventional
`hold equivalent' discretized system Σ Naive, which has generally been
believed, due to the ignoring of the intersample behavior, to be irrelevant
to the SR / CSR problems of Σ (and thus Σ DSP). We then establish that
there in fact exists an important relation between the seemingly completely
irrelevant discrete-time systems Σ DSP and Σ Naive. More precisely, we
show through the coprime factorization approach about Σ DSP and Σ Naive
that the CSR problem of Σ (and thus Σ DSP) is equivalent to a weighted
CSR problem of Σ Naive and that the SR problem of Σ is equivalent to
a weighted mixed sensitivity reduction problem of Σ Naive. In particular,
we show that the frequency-dependent weights that arise in this interplay
between Σ DSP and Σ Naive can be described with an important function
called the aliasing factor ψ, and further clarify an important analytic
property of ψ. We then demonstrate that this property of ψ can be used
to prove some relation between the best achievable performance in the SR
(respectively, CSR) problem of Σ DSP (and thus Σ) and that of Σ Naive.
An interesting property between the SR problem and CSR problem of Σ is
also provided.
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■ Characterization of Finite Frequency Properties Using Quadratic Differential
Forms
The Univ. of Tokyo・Chiaki KOJIMA,
The Central Japan Railway Company・Yusuke KAIZUKA,
and The Univ. of Tokyo・Shinji HARA
Many of practical design specifications are provided by finite frequency
properties described by inequalities over restricted finite frequency intervals.
A quadratic differential form (QDF) is a useful algebraic tool to characterize
energy and power functions when we consider dissipation theory based on
the behavioral approach. In this paper, we investigate time domain characterizations
of the finite frequency domain inequalities (FFDIs) using QDFs. QDFs allow
us to derive a clear characterization of the FFDIs using some inequality
in terms of them as a main result. This characterization leads to a physical
interpretation in terms of the dissipation inequality with the compensating
rate which guarantees dissipativity of {a} behavior with some rate constraints.
Such interpretation has not been clarified by the previous studies of finite
frequency properties. The aforementioned characterization yields an LMI
condition whose solvability is equivalent to the FFDIs. This can be regarded
as the finite frequency KYP lemma in the behavioral framework.
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■ Flood Monitoring and Early Warning System: The Integration of Inundated
Areas Extraction Tool
Keio Univ.・Ponthip LIMLAHAPUN and Hiromichi FUKUI
This paper examines a satellite images processing system with a mechanism
for detecting and responding to flood monitoring and warning. The interoperable
handling system is established in order to freely access the inundated
areas with no defensive barrier by the software operability limitations.
The ultimate goal of this effort is to bring awareness of the potentially
catastrophic occurrence that can be pre-detected and prevented altogether.
The development of the algorithm to extract the inundated areas and convey
urgent messages during the time of crisis are performed on a user-friendly
web based interface. A careful examination of various locations on LANDSAT
images yields promising results. Although the size of images is limited
by the available bandwidth of the web based application, processing at
4000*4000*3 bands per image takes approximately 3 minutes. This is a significant
improvement over currently available methods for inundated detection systems.
Additional benefits include software operation cost saving, and also reducing
in operational expenses and time. Furthermore, it does not require technical
expertise to predict the rise of flood disasters.
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