12309193
Building a Chinese Shallow Parsed TreeBank for Collocation Extraction
To automatically extract Chinese collocations and build a large-scale collocation bank, we are developing a one-million-word Chinese shallow parsed treebank. The treebank can be used not only as a training set for our shallow parser, but also as processed data from which collocations are extracted. This paper presents several issues related to this on-going project, such as our definition of shallow parsing used in Chinese collocation extraction, guideline preparation, and quality control.
1260337
An Improved k-Nearest Neighbor Algorithm for Text Categorization
k is the most important parameter in a text categorization system based on k-Nearest Neighbor algorithm (kNN).In the classification process, k nearest documents to the test one in the training set are determined firstly. Then, the predication can be made according to the category distribution among these k nearest neighbors. Generally speaking, the class distribution in the training set is uneven. Some classes may have more samples than others. Therefore, the system performance is very sensitive to the choice of the parameter k. And it is very likely that a fixed k value will result in a bias on large categories. To deal with these problems, we propose an improved kNN algorithm, which uses different numbers of nearest neighbors for different categories, rather than a fixed number across all categories. More samples (nearest neighbors) will be used for deciding whether a test document should be classified to a category, which has more samples in the training set. Preliminary experiments on Chinese text categorization show that our method is less sensitive to the parameter k than the traditional one, and it can properly classify documents belonging to smaller classes with a large k. The method is promising for some cases, where estimating the parameter k via cross-validation is not allowed.
71018
Experimental Study on Representing Units in Chinese Text Categorization
This paper is a comparative study on representing units in Chinese text categorization. Several kinds of representing units, including byte 3-gram, Chinese character, Chinese word, and Chinese word with part of speech tag, were investigated. Empirical evidence shows that when the size of training data is large enough, representations of higher-level or with larger feature spaces result in better performance than those of lower level or with smaller feature spaces, whereas when the training data is limited the conclusion may be the reverse. In general, representations of higher-level or with larger feature spaces need more training data to reach the best performance. But, as to a specific representation, the size of training data and the categorization performance are not always positively correlated.
17742402
A Unicode-based Adaptive Segmenter
This paper presents a Unicode based Chinese word segmentor. It can handle Chinese text in Simplified, Traditional, or mixed mode. The system uses the strategy of divide-and-conquer to handle the recognition of personal names, numbers, time and numerical values, etc in the preprocessing stage. The segmentor further uses tagging information to work on disambiguation. Adopting a modular design approach, different functional parts are separately implemented using different modules and each module tackles one problem at a time providing more flexibility and extensibility. Results show that with added pre-processing modules and accessorial modules, the accuracy of the segmentor is increased and the system is easily adaptive to different applications.
195606600
CTEMP: a chinese temporal parser for extracting and normalizing temporal information
Temporal information is useful in many NLP applications, such as information extraction, question answering and summarization. In this paper, we present a temporal parser for extracting and normalizing temporal expressions from Chinese texts. An integrated temporal framework is proposed, which includes basic temporal concepts and the classification of temporal expressions. The identification of temporal expressions is fulfilled by powerful chart-parsing based on grammar rules and constraint rules. We evaluated the system on a substantial corpus and obtained promising results.
34801552
Profile-based event tracking
In this research, we focus on tracking topics that originate and evolve from a specific event. Intuitively, a few key elements of a target event, such as date, location, and persons involved, would be enough for making a decision on whether a test story is on-topic. Consequently, a profile-based event tracking method is proposed. We attempt to build an event profile from the given on-topic stories by robust information retrieval technologies. A feature selection metric and a recognized event clause are utilized to determine most (if not all) key semantic elements of the target event. Preliminary experiments on the TDT2 mandarin corpus show that this profile-based event tracking method is promising.
8595308
Experiences with MPEG-4 multimedia streaming
With the advent of next-generation multimedia technologies such as very-low bit rate MPEG-4 codec, multimedia streaming of high-quality video and audio has become a near-term reality. The high compression ratio and error resilience offered by the MPEG-4 standard promise near-term popularity for rich contents and exceptional quality to consumers over affordable Internet connections, such as xDSL, cable modem and 3G wireless networks. Audio and video streaming applications are at the center of such scenarios; and Quality-of-Service (QoS) support in such applications is critical to their widespread acceptance.To the best of our knowledge, there has been no existing open-source MPEG-4 multimedia streaming applications in the academic community, which leads to the lack of research results using MPEG-4 streaming, especially with respect to Quality-of-Service support. In this work, we have implemented an open-source MPEG-4 multimedia streaming testbed in IP-based networks. In this paper, we show our experiences and lessons learned with such a testbed. First, we describe the algorithms and solutions used in our implemention testbed, emphasizing several critical issues. Second, through extensive experiments, we demonstrate measurements of bandwidth requirements and data loss for streaming a set of multimedia samples with different bit rates over UDP, which is ubiquitously available in the TCP/IP protocol stack on all consumer operating systems. Finally, future work for further improvements is also discussed.
2274256
Overlay Networks with Linear Capacity Constraints
Overlay networks are virtual networks residing over the IP network; consequently, overlay links may share hidden lower level bottlenecks. Previous work has assumed an independent overlay model: a graph with independent link capacities. We introduce a model of overlays that incorporates correlated link capacities and linear capacity constraints (LCC) to formulate hidden shared bottlenecks; we refer to these as LCC-overlays. We define metrics to qualitatively measure overlay quality in terms of its accuracy (in representing the true network topology) and efficiency (that is, performance). Through analysis and simulations, we show that LCC-overlay is perfectly accurate and, hence, enjoys much higher efficiency than the inaccurate independent overlay. We discover that even a highly restricted LCC class-node-based LCC-yields near-optimal accuracy and significantly higher efficiency. We study two network flow problems in the context of LCC-graphs: widest path and maximum flow. We prove that Widest Path with LCC is NP-complete. We formulate Maximum Flow with LCC as a linear program and propose an efficient distributed algorithm to solve it. Based on the LCC model, we further study the problem of optimizing delay while still maintaining optimal or near-optimal bandwidth. We also outline a distributed algorithm to efficiently construct an overlay with node-based LCC.
11775748
Schema Mapping for Interoperability in XML-based multidatabase
The main aim of a multidatabase system (MDBS) is to achieve data integration and interoperability among distributed and heterogeneous database systems. But data model heterogeneity and schema make this a challenging task. Multidatabase users can only view the global schemas whose real data come from local database systems. Thus, mappings from global schemas to local schemas should be established. At the same time, the recent emergence of XML has shown great intractability as a new standard for data representation and exchange on the Web. A data model based on XML becomes more suitable for integrating different types of systems. This paper firstly introduces a multidatabase common data model based on XML, named XML-based Integration Model (XIDM). Then, an approach of schema mappings based on XIDM in MDBSs has been presented. Finally, the illustration and implementation of schema mappings in a multidatabase prototype - Panorama are also discussed.
14174120
Overlay Multicast with Inferred Link Capacity Correlations
We model the overlay using linear capacity constraints, which accurately and succinctly capture overlay link correlations. We show that finding a maximum-bandwidth multicast tree in an overlay with LCC is NP-complete and propose an efficient distributed heuristics algorithm.
3580064
Bit section instruction set extension of ARM for embedded applications
Programs that manipulate data at subword level, i.e. bit sections within a word, are common place in the embedded domain. Examples of such applications include media processing as well as network processing codes. These applications spend significant amounts of time packing and unpacking narrow width data into memory words. The execution time and memory overhead of packing and unpacking operations can be greatly reduced by providing direct instruction set support for manipulating bit sections.In this paper we present the Bit Section eXtension (BSX) to the ARM instruction set. We selected the ARM processor for this research because it is one of the most popular embedded processor which is also being used as the basis of building many commercial network processing architectures. We present the design of BSX instructions and their encoding into the ARM instruction set. We have incorporated the implementation of BSX into the Simplescalar ARM simulator from Michigan. Results of experiments with programs from various benchmark suites show that by using BSX instructions the total number of instructions executed at runtime by many transformed functions are reduced by 4.26% to 27.27% and their code sizes are reduced by `1.27% to 21.05%.