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991.
The optimal tracking problem for multiple‐input multiple‐output linear‐time‐invariant discrete‐time systems with communication constraints in the feedback path is studied in this paper. The tracking performance is measured by the energy of the error signal between the output of the plant and the reference signal. The objective is to obtain an optimal tracking performance, attainable by all possible stabilizing compensators. It is shown that the optimal tracking performance consists of two parts, one depends on the nonminimum phase zeros and zero direction of the given plant, as well as the reference input signal direction, and the other depends on the nonminimum phase zeros, unstable poles, and pole direction of the given plant, as well as the bandwidth and additive white Gaussian noise of the communication channel. It is also shown that, if the constraint of the communication channel does not exist, the optimal tracking performance reduces to the existing tracking performance of the control system without communication constraints. A typical example is given to illustrate the theoretical results. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
992.
Gary Gibson Xia Sheng Dick Henze Si‐Ty Lam Patricia Beck Yoocharn Jeon Zhang‐Lin Zhou Brad Benson Qin Liu Gregg Combs Tim Koch Kent Biggs 《Journal of the Society for Information Display》2012,20(10):552-558
Reflective displays are advantageous in applications requiring low power or daylight readability. However, there are no low‐cost reflective technologies capable of displaying bright colors. By employing photoluminescence to more efficiently use ambient light, we created a prototype display that provides bright, full color in a simple, low‐cost architecture. This prototype includes a novel electrokinetic shutter, a layer that incorporates patterned luminescent red, green, and blue sub‐pixel elements, and a novel optical out‐coupling scheme. The luminescent elements convert otherwise‐wasted portions of the incident spectrum to light in the desired color band, resulting in improved color saturation and lightness. This prototype provides a color gamut that is superior to competing reflective display technologies that utilize color filters in single‐layer side‐by‐side sub‐pixel architectures. The current prototype is capable of switching in <0.5 s; future displays based on an alternative electro‐optic shutter technology should achieve video rate operation. A transflective version of this technology has also been prototyped. The transflective version utilizes its backlight with a power efficiency that is at least three times that of a conventional liquid crystal display. These photoluminescence‐based technologies enable a host of applications ranging from low‐power mobile products and retail pricing signage to daylight readable signage for outdoor advertising segments. 相似文献
993.
In this paper, we present an efficient way of implementing OpenGL ES 1.1 3D graphics API library for the environments with
hardware-supported OpenGL facility, typically as desktop PCs. Although OpenGL ES was started from the existing OpenGL features,
it rapidly became the standard 3D graphics library customized for embedded systems through introducing fixed-point arithmetic
operations, buffer management with fixed-point data type supports, completely new texture mapping functions and others. Currently,
it is the official 3D graphics API for Google Android, Apple iPhone, Sony PlayStation3, etc. In this paper, we achieved improvements
on the arithmetic operations for the fixed-point number representation, which is the most characteristic data type for OpenGL
ES 1.1. For the conversion of fixed-point data types to the floating-point number representations for the underlying OpenGL,
we show the way of efficient conversion processes even with satisfying OpenGL ES standard requirements. We also introduced
a specialized memory management scheme to manage the converted data from the buffer containing fixed-point numbers. In the
case of texture processing, the requirements in both standards are quite different, and thus we used completely new software-implementations.
Our final implementation of OpenGL ES library provides all of more than 200 functions in the standard specification and passed
its conformance test, to show its compliance with the standard. From the efficiency point of view, we measured its execution
times for several OpenGL ES-specific application programs and achieved remarkable improvements. 相似文献
994.
In this paper, we present AutoMed, an automated mediator for multi-issue bilateral negotiation under time constraints. AutoMed
elicits the negotiators preferences and analyzes them. It monitors the negotiations and proposes possible solutions for resolving
the conflict. We conducted experiments in a simulated environment. The results show that negotiations mediated by AutoMed
are concluded significantly faster than non-mediated ones and without any of the negotiators opting out. Furthermore, the
subjects in the mediated negotiations are more satisfied with the resolutions than the subjects in the non-mediated negotiations. 相似文献
995.
In this paper, we present a formulation of the quaternion constraint for rigid body rotations in the form of a standard perfect
bilateral mechanical constraint, for which the associated Lagrangian multiplier has the meaning of a constraint force. First,
the equations of motion of a scalable body are derived. A scalable body has three translational, three rotational, and one
uniform scaling degree of freedom. As generalized coordinates, an unconstrained quaternion and a displacement vector are used.
To the scalable body, a perfect bilateral constraint is added, restricting the quaternion to unit length and making the body
rigid. This way a quaternion based differential algebraic equation (DAE) formulation for the dynamics of a rigid body is obtained,
where the 7×7 mass matrix is regular and the unit length restriction of the quaternion is enforced by a mechanical constraint.
Finally, the equations of motion in the form of a DAE are linked to the Newton–Euler equations of motion of a rigid body.
The rigid body DAE formulation is useful for the construction of (energy) consistent integrators. 相似文献
996.
Bettina Berendt 《Data mining and knowledge discovery》2012,24(3):697-737
Over the last decade, privacy has been widely recognised as one of the major problems of data collections in general and the
Web in particular. This concerns specifically data arising from Web usage (such as querying or transacting) and social networking
(characterised by rich self-profiling including relational information) and the inferences drawn from them. The data mining
community has been very conscious of these issues and has addressed in particular the inference problems through various methods
for “privacy-preserving data mining” and “privacy-preserving data publishing”. However, it appears that these approaches by
themselves cannot effectively solve the privacy problems posed by mining. We argue that this is due to the underlying notions
of privacy and of data mining, both of which are too narrow. Drawing on notions of privacy not only as hiding, but as control
and negotiation, as well as on data mining not only as modelling, but as the whole cycle of knowledge discovery, we offer
an alternative view. This is intended to be a comprehensive view of the privacy challenges as well as solution approaches
along all phases of the knowledge discovery cycle. The paper thus combines a survey with an outline of an agenda for a comprehensive,
interdisciplinary view of Web mining and privacy. 相似文献
997.
Efficient compression and network adaptive video coding for distributed video surveillance 总被引:1,自引:1,他引:0
The availability of cheap network based video cameras and the prevalence of wireless networks has lead to a major thrust towards
deployment of large scale Distributed Video Surveillance (DVS) systems. This has opened up an important area of research to
deal with the issues involved in DVS system for efficient collection and transmission of large scale video streams from the
cameras at the guarded sites, to the end users in possibly constrained network conditions. In this paper, we propose a framework
based on content-based video classification and scalable compression scheme to provide a robust bandwidth efficient video
transmission for DVS. The scheme builds on a Discrete Wavelet Transform (DWT) based Color-Set Partitioning for Hierarchical
Trees (CSPIHT) coding to obtain a scalable bitstream. Wavelet domain segmentation and compression assists in development of
a DVS architecture. The architecture includes a novel module for dynamic allocation of Network bandwidth based on the current
available resources and constraints. Different frame constituents are optimally coded based on their relative significance,
perceptual quality, and available estimate of network bandwidth. Experimental result over different video sequences and simulations
for Network conditions demonstrate the efficient performance of the approach. 相似文献
998.
Guang-Ho Cha 《Multimedia Tools and Applications》2012,56(2):351-364
One of the central problems regarding media search is the semantic gap between the low-level features computed automatically
from media data and the human interpretation of them. This is because the notion of similarity is usually based on high-level
abstraction but the low-level features do not sometimes reflect the human perception. In this paper, we assume the semantics
of media is determined by the contextual relationship in a dataset, and introduce the method to capture the contextual information from a large media (especially
image) dataset for effective search. Similarity search in an image database based on this contextual information shows encouraging
experimental results. 相似文献
999.
The paper proposes a new approach to find semantic meanings in visual object class structure, in line with the Gestalt laws
of proximity. Micro level semantic structures are formed by line segments (arcs also approximated into line segments based
on pixel deviation threshold) which are in close proximity. These structures are hierarchically combined till a semantic label
can be assigned. The algorithm extracts semantic groups, their inter-relations and represents these using a graph. Invariant
geometrical properties of the groups and relations are used as vertex and edge labels. A graph model captures the inter class
variability by analyzing the repetitiveness of structures and relations and uses it as a weighting factor for classification.
The algorithm has been tested on a standard benchmark database and compared with existing approaches. 相似文献
1000.
Hugo Feitosa de Figueirêdo Yuri Almeida Lacerda Anselmo Cardoso de Paiva Marco Antonio Casanova Cláudio de Souza Baptista 《Multimedia Tools and Applications》2012,59(1):279-305
The recent popularity of digital cameras has posed a new problem: how to efficiently store and retrieve the very large number
of digital photos captured and chaotically stored in multiple locations without any annotation. This paper proposes an infrastructure,
called PhotoGeo, which aims at helping users with the people photo annotation, event photo annotation, storage and retrieval
of personal digital photos. To achieve the desired objective, PhotoGeo uses new algorithms that make it possible to annotate
photos with the key metadata to facilitate their retrieval, such as: the people who were shown in the photo (who); where it was captured (where); the date and time of capture (when); and the event that was captured. The paper concludes with a detailed evaluation of these algorithms. 相似文献