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61.
Torresani L Hertzmann A Bregler C 《IEEE transactions on pattern analysis and machine intelligence》2008,30(5):878-892
This paper describes methods for recovering time-varying shape and motion of non-rigid 3D objects from uncalibrated 2D point tracks. For example, given a video recording of a talking person, we would like to estimate the 3D shape of the face at each instant, and learn a model of facial deformation. Time-varying shape is modeled as a rigid transformation combined with a non-rigid deformation. Reconstruction is ill-posed if arbitrary deformations are allowed, and thus additional assumptions about deformations are required. We first suggest restricting shapes to lie within a low-dimensional subspace, and describe estimation algorithms. However, this restriction alone is insufficient to constrain reconstruction. To address these problems, we propose a reconstruction method using a Probabilistic Principal Components Analysis (PPCA) shape model, and an estimation algorithm that simultaneously estimates 3D shape and motion for each instant, learns the PPCA model parameters, and robustly fills-in missing data points. We then extend the model to model temporal dynamics in object shape, allowing the algorithm to robustly handle severe cases of missing data. 相似文献
62.
Concept assignment identifies units of source code that are functionally related, even if this is not apparent from a syntactic point of view. Until now, the results of concept assignment have only been used for static analysis, mostly of program source code. This paper investigates the possibility of using concept information within a framework for dynamic analysis of programs. The paper presents two case studies involving a small Java program used in a previous research exercise, and a large Java virtual machine (the popular Jikes RVM system). These studies investigate two applications of dynamic concept information: visualization and profiling. The paper demonstrates two different styles of concept visualization, which show the proportion of overall time spent in each concept and the sequence of concept execution, respectively. The profiling study concerns the interaction between runtime compilation and garbage collection in Jikes RVM. For some benchmark cases, we are able to obtain a significant reduction in garbage collection time. We discuss how this phenomenon might be harnessed to optimize the scheduling of garbage collection in Jikes RVM. 相似文献
63.
In this paper, we describe an implementation of use in demonstrating the effectiveness of architectures for real-time multi-agent
systems. The implementation provides a simulation of a simplified RoboCup Search and Rescue environment, with unexpected events,
and includes a simulator for both a real-time operating system and a CPU. We present experimental evidence to demonstrate
the benefit of the implementation in the context of a particular hybrid architecture for multi-agent systems that allows certain
agents to remain fully autonomous, while others are fully controlled by a coordinating agent. In addition, we discuss the
value of the implementation for testing any models for the construction of real-time multi-agent systems and include a comparison
to related work.
相似文献
Robin CohenEmail: |
64.
Chris Hinds 《Requirements Engineering》2008,13(4):315-328
Requirements engineering is a field with a heavy practical emphasis and for the most part is quite rightly unconcerned with
philosophical reflection. However, there have been exceptions. Philosophical arguments are important because they can be used
to powerful effect, facilitating explicit debate on views that may previously have been implicit, and shaping the direction
of thought and research within the field. Several cases from both requirements engineering and software engineering have given
prominence to the philosophy of positivism. This paper will outline arguments against such a view.
相似文献
Chris HindsEmail: |
65.
Andrew Grayland Chris Jefferson Ian Miguel Colva M. Roney-Dougal 《Annals of Mathematics and Artificial Intelligence》2009,57(1):75-102
Variable symmetries in a constraint satisfaction problem can be broken by adding lexicographic ordering constraints. Existing general methods of generating such sets of ordering constraints can require a huge number of constraints. This adds an unacceptable overhead to the solving process. Methods exist by which this large set of ordering constraints can be reduced to a much smaller set automatically, but their application is also prohibitively costly. In contrast, this paper takes a bottom-up approach. It examines some commonly-occurring families of groups and derives a minimal set of ordering constraints sufficient to break the symmetry each group describes. These minimal sets are then used as building blocks to generate minimal sets of ordering constraints for groups constructed via direct and imprimitive wreath products. Experimental results confirm the value of minimal sets of ordering constraints, which can now be generated much more cheaply than with previous methods. 相似文献
66.
Ilias Maglogiannis Demosthenes Vouyioukas Chris Aggelopoulos 《Personal and Ubiquitous Computing》2009,13(1):95-101
This paper presents an integrated system for emotion detection. In this research effort, we have taken into account the fact
that emotions are most widely represented with eye and mouth expressions. The proposed system uses color images and it is
consisted of three modules. The first module implements skin detection, using Markov random fields models for image segmentation
and skin detection. A set of several colored images with human faces have been considered as the training set. A second module
is responsible for eye and mouth detection and extraction. The specific module uses the HLV color space of the specified eye
and mouth region. The third module detects the emotions pictured in the eyes and mouth, using edge detection and measuring
the gradient of eyes’ and mouth’s region figure. The paper provides results from the system application, along with proposals
for further research. 相似文献
67.
The assessment of the social impacts of road traffic is usually based on objective indicators or on expert judgement, without input from the affected communities. This paper considers the perceptions and priorities of local residents about traffic impacts and possible mitigation measures, using as a case study a rural area that will be affected by traffic associated with the construction of a nuclear power station. The study consisted of a qualitative phase followed by a stated preference survey. Econometric models were used to measure the relative priority of different impacts and mitigation measures. The most impactful aspects were noise, vibration and increased car or bus travel times. The most preferred measures were night-time restrictions to HGVs, parking restrictions and safety measures for pedestrians and cyclists. There were significant differences in preferences according to residence location, gender, employment status and household composition. The results provide information about aspects that tend to be aggregated in existing assessment frameworks, separating the reduction in the utility of some activities (like walking and driving) and the suppression of those activities. 相似文献
68.
Formal Specification and Quantitative Analysis of a Constellation of Navigation Satellites 下载免费PDF全文
Zhaoguang Peng Yu Lu Alice Miller Tingdi Zhao Chris Johnson 《Quality and Reliability Engineering International》2016,32(2):345-361
Navigation satellites are a core component of navigation satellite‐based systems such as Global Positioning System, Global Navigation Satellite System and Galileo, which provide location and timing information for a variety of uses. Such satellites are designed for operating on orbit to perform tasks and have lifetimes of 10 years or more. Reliability, availability and maintainability analysis of systems has been indispensable in the design phase of satellites in order to achieve minimum failures or to increase mean time between failures and thus to plan maintenance strategies, optimise reliability and maximise availability. In this paper, we present formal models of both a single satellite and a navigation satellite constellation and logical specification of their reliability, availability and maintainability properties, respectively. The probabilistic model checker PRISM has been used to perform automated analysis of these quantitative properties. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
69.
Triple Emulsion Drops with An Ultrathin Water Layer: High Encapsulation Efficiency and Enhanced Cargo Retention in Microcapsules 下载免费PDF全文
70.