A new method of color image segmentation is proposed in this paper. It's based on K-means algorit... more A new method of color image segmentation is proposed in this paper. It's based on K-means algorithm in HSI space and has the advantage over those based on the RGB space. Both the hue and the intensity components are fully utilized. In the process of hue clustering, the special cyclic property of the hue component is taken into consideration. The paper gives the definition of the distance and the center in the hue space, based on which the hue-clustering algorithm is implemented. Utilized in medical image processing, the new method has got a good performance.
We consider the problem of locating a robot in an initially-unfamiliar environment from visual in... more We consider the problem of locating a robot in an initially-unfamiliar environment from visual input. The robot is not given a map of the environment, but it does have access to a collection of training examples, each of which specifies the video image observed when the robot is at a particular location and orientation. We address two variants of this problem: how to estimate translation of a moving robot assuming the orientation is known, and how to estimate translation and orientation for a mobile robot. Performing scene reconstruction to construct a metric map of the environment using only video images is difficult. We avoid this by using an approach in which the robot learns to convert a set of image measurements into a representation of its pose (position and orientation). This provides a metric estimate of the robot's location within a region covered by the statistical map we build. Localization can be performed online without a prior location estimate, The conversion from visual data to camera pose is implemented using a multilayer neural network that is trained using backpropagation. An aspect of the approach is the use of an inconsistency measure to eliminate incorrect data and estimate components of the pose vector. The experimental data reported in this paper suggests that the accuracy and flexibility of the technique is good, while the online computational cost is very low
This paper presents the design and implementation of a mobile storage system called a Personal-RA... more This paper presents the design and implementation of a mobile storage system called a Personal-RAID. PersonalRAID manages a number of disconnected storage devices. At the heart of a Personal-RAID system is a mobile storage device that transparently propagates data to ensure eventual consistency. Using this mobile device, a PersonalRAID provides the abstraction of a single coherent storage name space that is available everywhere, and it ensures reliability by maintaining data redundancy on a number of storage devices. One central aspect of the PersonalRAID design is that the entire storage system consists solely of a collection of storage logs; the log-structured design not only provides an efficient means for update propagation, but also allows efficient direct I/O accesses to the logs without incurring unnecessary log replay delays. The PersonalRAID prototype demonstrates that the system provides the desired transparency and reliability functionalities without imposing any serious performance penalty on a mobile storage user.
Indexing of high-dimensional data is essential for building applications such as multimedia retri... more Indexing of high-dimensional data is essential for building applications such as multimedia retrieval, data mining, and spatial databases. Traditional index structures rely on centralized processing. This approach does not scale with the rapidly increasing amount of application data available on massively distributed systems like the Internet.
Detecting network path anomalies generally requires examining large volumes of traffic data to fi... more Detecting network path anomalies generally requires examining large volumes of traffic data to find misbehavior. We observe that wide-area services, such as peerto-peer systems and content distribution networks, exhibit large traffic volumes, spread over large numbers of geographically-dispersed endpoints. This makes them ideal candidates for observing wide-area network behavior. Specifically, we can combine passive monitoring of wide-area traffic to detect anomalous network behavior, with active probes from multiple nodes to quantify and characterize the scope of these anomalies.
This paper presents a distributed mobile storage system designed for storage elements connected b... more This paper presents a distributed mobile storage system designed for storage elements connected by a network of non-uniform quality. Flexible data placement is crucial, and it leads to challenges for locating data and keeping it consistent. Our system employs a locationand topology-sensitive multicast-like solution for locating data, lazy peer-to-peer propagation of invalidation information for ensuring consistency, and a distributed snapshot mechanism for supporting sharing. The combination of these mechanisms allows a user to make the most of what a non-uniform network has to offer in terms of gaining fast access to fresh data, without incurring the foreground penalty of keeping distributed elements on a weak network consistent.
There is an increasing demand for locality-preserving distribution of complex data structures in ... more There is an increasing demand for locality-preserving distribution of complex data structures in peer-to-peer systems. Current systems either do not preserve object locality or suffer from imbalances in data distribution, routing state, and/or query processing costs. In this position paper, we take a systematic approach that enables the deployment of searchable tree structures in p2p environments. We achieve distributed tree traversal with efficient routing distance and routing state. We show how to implement several p2p applications using distributed tree structures.
This paper is motivated by a simple question: what are the energy consumption characteristics of ... more This paper is motivated by a simple question: what are the energy consumption characteristics of mobile storage alternatives? To answer this question, we are faced with a design space of multiple dimensions. Two important dimensions are the type of storage technologies and the type of file systems. In this paper, we explore some options along each of these two dimensions. We have constructed a logical-disk system, which can be configured to run on different storage technologies and to emulate the behavior of different file systems. As we explore these configuration options, we find that the energy behavior is determined by a complex interaction of three factors: the power management mechanism of the storage device, the distribution of idleness in the workload, and the file system strategies that attempt to exploit and bridge these first two factors.
A new method of color image segmentation is proposed in this paper. It's based on K-means algorit... more A new method of color image segmentation is proposed in this paper. It's based on K-means algorithm in HSI space and has the advantage over those based on the RGB space. Both the hue and the intensity components are fully utilized. In the process of hue clustering, the special cyclic property of the hue component is taken into consideration. The paper gives the definition of the distance and the center in the hue space, based on which the hue-clustering algorithm is implemented. Utilized in medical image processing, the new method has got a good performance.
We consider the problem of locating a robot in an initially-unfamiliar environment from visual in... more We consider the problem of locating a robot in an initially-unfamiliar environment from visual input. The robot is not given a map of the environment, but it does have access to a collection of training examples, each of which specifies the video image observed when the robot is at a particular location and orientation. We address two variants of this problem: how to estimate translation of a moving robot assuming the orientation is known, and how to estimate translation and orientation for a mobile robot. Performing scene reconstruction to construct a metric map of the environment using only video images is difficult. We avoid this by using an approach in which the robot learns to convert a set of image measurements into a representation of its pose (position and orientation). This provides a metric estimate of the robot's location within a region covered by the statistical map we build. Localization can be performed online without a prior location estimate, The conversion from visual data to camera pose is implemented using a multilayer neural network that is trained using backpropagation. An aspect of the approach is the use of an inconsistency measure to eliminate incorrect data and estimate components of the pose vector. The experimental data reported in this paper suggests that the accuracy and flexibility of the technique is good, while the online computational cost is very low
This paper presents the design and implementation of a mobile storage system called a Personal-RA... more This paper presents the design and implementation of a mobile storage system called a Personal-RAID. PersonalRAID manages a number of disconnected storage devices. At the heart of a Personal-RAID system is a mobile storage device that transparently propagates data to ensure eventual consistency. Using this mobile device, a PersonalRAID provides the abstraction of a single coherent storage name space that is available everywhere, and it ensures reliability by maintaining data redundancy on a number of storage devices. One central aspect of the PersonalRAID design is that the entire storage system consists solely of a collection of storage logs; the log-structured design not only provides an efficient means for update propagation, but also allows efficient direct I/O accesses to the logs without incurring unnecessary log replay delays. The PersonalRAID prototype demonstrates that the system provides the desired transparency and reliability functionalities without imposing any serious performance penalty on a mobile storage user.
Indexing of high-dimensional data is essential for building applications such as multimedia retri... more Indexing of high-dimensional data is essential for building applications such as multimedia retrieval, data mining, and spatial databases. Traditional index structures rely on centralized processing. This approach does not scale with the rapidly increasing amount of application data available on massively distributed systems like the Internet.
Detecting network path anomalies generally requires examining large volumes of traffic data to fi... more Detecting network path anomalies generally requires examining large volumes of traffic data to find misbehavior. We observe that wide-area services, such as peerto-peer systems and content distribution networks, exhibit large traffic volumes, spread over large numbers of geographically-dispersed endpoints. This makes them ideal candidates for observing wide-area network behavior. Specifically, we can combine passive monitoring of wide-area traffic to detect anomalous network behavior, with active probes from multiple nodes to quantify and characterize the scope of these anomalies.
This paper presents a distributed mobile storage system designed for storage elements connected b... more This paper presents a distributed mobile storage system designed for storage elements connected by a network of non-uniform quality. Flexible data placement is crucial, and it leads to challenges for locating data and keeping it consistent. Our system employs a locationand topology-sensitive multicast-like solution for locating data, lazy peer-to-peer propagation of invalidation information for ensuring consistency, and a distributed snapshot mechanism for supporting sharing. The combination of these mechanisms allows a user to make the most of what a non-uniform network has to offer in terms of gaining fast access to fresh data, without incurring the foreground penalty of keeping distributed elements on a weak network consistent.
There is an increasing demand for locality-preserving distribution of complex data structures in ... more There is an increasing demand for locality-preserving distribution of complex data structures in peer-to-peer systems. Current systems either do not preserve object locality or suffer from imbalances in data distribution, routing state, and/or query processing costs. In this position paper, we take a systematic approach that enables the deployment of searchable tree structures in p2p environments. We achieve distributed tree traversal with efficient routing distance and routing state. We show how to implement several p2p applications using distributed tree structures.
This paper is motivated by a simple question: what are the energy consumption characteristics of ... more This paper is motivated by a simple question: what are the energy consumption characteristics of mobile storage alternatives? To answer this question, we are faced with a design space of multiple dimensions. Two important dimensions are the type of storage technologies and the type of file systems. In this paper, we explore some options along each of these two dimensions. We have constructed a logical-disk system, which can be configured to run on different storage technologies and to emulate the behavior of different file systems. As we explore these configuration options, we find that the energy behavior is determined by a complex interaction of three factors: the power management mechanism of the storage device, the distribution of idleness in the workload, and the file system strategies that attempt to exploit and bridge these first two factors.
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Papers by Chi Zhang