Urbanization is a global trend that we have all witnessed in the past decades. It brings us both opportunities and challenges. On the one hand, urban system is one of the most sophisticated social-economic systems that is responsible for efficiently providing supplies meeting the demand of residents in various of domains, e.g., dwelling, education, entertainment, healthcare, etc. On the other hand, significant diversity and inequality exist in the development patterns of urban systems, which makes urban data analysis difficult. Different urban regions often exhibit diverse urbanization patterns and provide distinct urban functions, e.g., commercial and residential areas offer significantly different urban functions. It is desired to develop the data analytic capabilities for discovering the underlying cross-domain urbanization patterns, clustering urban regions based on their function similarity and predicting region popularity in specified domains. Previous studies in the urban data analysis area often just focus on individual domains and rarely consider cross-domain urban development patterns hidden in different urban regions. In this paper, we propose the infinite urbanization process (IUP) model for simultaneous urban region function discovery and region popularity prediction. The IUP model is a generative Bayesian nonparametric process that is capable of describing a potentially infinite number of urbanization patterns. It is developed within the supervised topic modelling framework and is supported by a novel hierarchical spatial distance dependent Bayesian nonparametric prior over the spatial region partition space. The empirical study conducted on the real-world datasets shows promising outcome compared with the state-of-the-art techniques.

Peer-to-peer networking offers a scalable solution for sharing multimedia data across the network. With a large amount of visual data distributed among different nodes, it is an important but challenging issue to perform content-based retrieval in peer-to-peer networks. While most of the existing methods focus on indexing high dimensional visual features and have limitations of scalability, in this paper we propose a scalable approach for content-based image retrieval in peer-to-peer networks by employing the bag-of-visual-words model. Compared with centralized environments, the key challenge is to efficiently obtain a global codebook, as images are distributed across the whole peer-to-peer network. In addition, a peer-to-peer network often evolves dynamically, which makes a static codebook less effective for retrieval tasks. Therefore, we propose a dynamic codebook updating method by optimizing the mutual information between the resultant codebook and relevance information, and the workload balance among nodes that manage different codewords. In order to further improve retrieval performance and reduce network cost, indexing pruning techniques are developed. Our comprehensive experimental results indicate that the proposed approach is scalable in evolving and distributed peer-to-peer networks, while achieving improved retrieval accuracy.

The bag-of-visual-words model has been widely utilized for content based image and video retrieval due to its scalability. In this paper, we extend this model for human action video retrieval. We adopt dense trajectory features which are able to achieve the state-of-the-art performance on action recognition, while most of the existing video retrieval methods utilize descriptors of local interest points. In order to improve similarity measurement between bag-of-visual-words model based representation, we propose to discover and incorporate spatial-temporal correlation (STC) among the trajectories in a given query video. The spatial-temporal correlation consists of spatial proximity and temporal consistence among trajectories, which is capable of strengthening discriminative power among visual words. Note that such query focused spatial-temporal correlation makes our method dynamic for different queries and is able to improve retrieval performance without significantly increasing the size of a visual vocabulary. The experimental results on an action video dataset demonstrate that our proposed method outperforms other similar methods.

The multi-view/multi-modal features are commonly used in neuroimaging classification because they could provide complementary information to each other and thus result in better classification performance than single-view features. However, it is very challenging to effectively integrate such rich features, since straightforward concatenation or singleview spectral embedding methods rarely leads to physically meaningful integration. In this paper, we present a supervised multi-view/multi-modal spectral embedding method (SMSE) for neuroimaging classification. This method embeds the high dimensional multi-view features derived from multi-modal neuroimaging data into a low dimensional feature space and preserves the optimal local embeddings among different views. The proposed SMSE algorithm, validated using three groups of neuroimaging data, is able to achieve significant classification improvement over the state-of-the-art multi-view spectral embedding methods.

Relevance feedback (RF) allows users to be actively involved in the information retrieval process and has been widely used in various information retrieval tasks. While most existing RF methods in content-based image retrieval (CBIR) focus on visual features of individual images only, in this paper we formulate the relevance feedback process as an energy minimization problem. The energy function takes into account both the feature aspect of each image and the manifold structure among individual images. The solution of labelling images as relevant or irrelevant is obtained with the graph cuts method. As a result, our method enables flexibly partitioning the feature space and labelling of images and is capable of handling challenging scenarios (or queries). Experimental results demonstrate that our proposed method outperforms the popular RF methods.

Supporting complex and efficient lookup queries in peer-to-peer networks is challenging, though simple keyword based lookup queries are well supported by most deployed systems. This paper presents a two-level indexing structure built on distributed hash table (DHT) aiming to support range queries on high-dimensional feature space in peer-to-peer network. Unlike most existing systems, where every node is responsible for a data partition, our design only utilizes a small part of the nodes to manage partitions. These partition nodes form the first level index. The second level index consists of one or more server nodes, which maintains links to each partition node. Additionally, a merge and split mechanism is designed to dynamically adjust the workload among nodes. Experimental results indicate that our system offers promising performance in terms of workload balance in churn networks. The flexibility to work with any DHT and the capability to support multiple feature spaces further make our proposed approach a feasible extension for file sharing networks.

A novel cell nucleus tracking approach is raised in this paper, developed from applied graph theory that simultaneously handles major challenges of cells touching, splitting, disappearing and emerging. The key point of our work lies in the graphs with robust structures that constructed from large cells groups. Then the problem of nucleus tracking is simplified to that of vertex matching between graphs generated from successive frames. Single cells are modeled as vertices in the graph and edges are built between neighboring ones, through which cells in large quantities are connected altogether. The algorithm works through a process of graph saturation following vertices with maximal entering belief-propagation flows. Feasibility of our approach is validated by so-called 'Crowds Model' that explains motional features of multi-cells groups. In processing CT image sources with high cell intensities as well as complex variations in structures, robustness of our approach is confirmed in that both successful tracking rates and segmentation rates are kept above 96%.