MonetDB/XQuery: a fast XQuery processor powered by a relational engine

Relational XQuery systems try to re-use mature relational data management infrastructures to create fast and scalable XML database technology. This paper describes the main features, key contributions, and lessons learned while implementing such a system. Its architecture consists of (i) a range-based encoding of XML documents into relational tables, (ii) a compilation technique that translates XQuery into a basic relational algebra, (iii) a restricted (order) property-aware peephole relational query optimization strategy, and (iv) a mapping from XML update statements into relational updates. Thus, this system implements all essential XML database functionalities (rather than a single feature) such that we can learn from the full consequences of our architectural decisions. While implementing this system, we had to extend the state-of-the-art with a number of new technical contributions, such as loop-lifted staircase join and efficient relational query evaluation strategies for XQuery theta-joins with existential semantics. These contributions as well as the architectural lessons learned are also deemed valuable for other relational back-end engines. The performance and scalability of the resulting system is evaluated on the XMark benchmark up to data sizes of 11GB. The performance section also provides an extensive benchmark comparison of all major XMark results published previously, which confirm that the goal of purely relational XQuery processing, namely speed and scalability, was met

On the performance of markup language compression

Data compression is used in our everyday life to improve computer interaction or simply for storage purposes. Lossless data compression refers to those techniques that are able to compress a file in such ways that the decompressed format is the replica of the original. These techniques, which differ from the lossy data compression, are necessary and heavily used in order to reduce resource usage and improve storage and transmission speeds. Prior research led to huge improvements in compression performance and efficiency for general purpose tools which are mainly based on statistical and dictionary encoding techniques. Extensible Markup Language (XML) is based on redundant data which is parsed as normal text by general-purpose compressors. Several tools for compressing XML data have been developed, resulting in improvements for compression size and speed using different compression techniques. These tools are mostly based on algorithms that rely on variable length encoding. XML Schema is a language used to define the structure and data types of an XML document. As a result of this, it provides XML compression tools additional information that can be used to improve compression efficiency. In addition, XML Schema is also used for validating XML data. For document compression there is a need to generate the schema dynamically for each XML file. This solution can be applied to improve the efficiency of XML compressors. This research investigates a dynamic approach to compress XML data using a hybrid compression tool. This model allows the compression of XML data using variable and fixed length encoding techniques when their best use cases are triggered. The aim of this research is to investigate the use of fixed length encoding techniques to support general-purpose XML compressors. The results demonstrate the possibility of improving on compression size when a fixed length encoder is used to compressed most XML data types

SYNTHNOTES: TOWARDS SYNTHETIC CLINICAL TEXT GENERATION

SynthNotes is a statistical natural language generation tool for the creation of realistic medical text notes for use by researchers in clinical language processing. Currently, advancements in medical analytics research face barriers due to patient privacy concerns which limits the numbers of researchers who have access to valuable data. Furthermore, privacy protections restrict the computing environments where data can be processed. This often adds prohibitive costs to researchers. The generation method described here provides domain-independent statistical methods for learning to generate text by extracting and ranking templates from a training corpus. The primary contribution in this work is automating the process of template selection and generation of text through classic machine learning methods. SynthNotes removes the need for human domain experts to construct templates, which can be time intensive and expensive. Furthermore, by using machine learning methods, this approach leads to greater realism and variability in the generated notes than could be achieved through classical language generation methods

Building an Emulation Environment for Cyber Security Analyses of Complex Networked Systems

Computer networks are undergoing a phenomenal growth, driven by the rapidly increasing number of nodes constituting the networks. At the same time, the number of security threats on Internet and intranet networks is constantly growing, and the testing and experimentation of cyber defense solutions requires the availability of separate, test environments that best emulate the complexity of a real system. Such environments support the deployment and monitoring of complex mission-driven network scenarios, thus enabling the study of cyber defense strategies under real and controllable traffic and attack scenarios. In this paper, we propose a methodology that makes use of a combination of techniques of network and security assessment, and the use of cloud technologies to build an emulation environment with adjustable degree of affinity with respect to actual reference networks or planned systems. As a byproduct, starting from a specific study case, we collected a dataset consisting of complete network traces comprising benign and malicious traffic, which is feature-rich and publicly available

Methods and Applications of Synthetic Data Generation

The advent of data mining and machine learning has highlighted the value of large and varied sources of data, while increasing the demand for synthetic data captures the structural and statistical characteristics of the original data without revealing personal or proprietary information contained in the original dataset. In this dissertation, we use examples from original research to show that, using appropriate models and input parameters, synthetic data that mimics the characteristics of real data can be generated with sufficient rate and quality to address the volume, structural complexity, and statistical variation requirements of research and development of digital information processing systems. First, we present a progression of research studies using a variety of tools to generate synthetic network traffic patterns, enabling us to observe relationships between network latency and communication pattern benchmarks at all levels of the network stack. We then present a framework for synthesizing large scale IoT data with complex structural characteristics in a scalable extraction and synthesis framework, and demonstrate the use of generated data in the benchmarking of IoT middleware. Finally, we detail research on synthetic image generation for deep learning models using 3D modeling. We find that synthetic images can be an effective technique for augmenting limited sets of real training data, and in use cases that benefit from incremental training or model specialization, we find that pretraining on synthetic images provided a usable base model for transfer learning

Combining Statistical Parameteric Speech Synthesis and Unit-Selection for Automatic Voice Cloning

The ability to use the recorded audio of a subject's voice to produce an open-domain synthesis system has generated much interest both in academic research and in commercial speech technology. The ability to produce synthetic versions of a subjects voice has potential commercial applications, such as virtual celebrity actors, or potential clinical applications, such as offering a synthetic replacement voice in the case of a laryngectomy. Recent developments in HMM-based speech synthesis have shown it is possible to produce synthetic voices from quite small amounts of speech data. However, mimicking the depth and variation of a speaker's prosody as well as synthesising natural voice quality is still a challenging research problem. In contrast, unit-selection systems have shown it is possible to strongly retain the character of the voice but only with sufficient original source material. Often this runs into hours and may require significant manual checking and labelling. In this paper we will present two state of the art systems, an HMM based system HTS-2007, developed by CSTR and Nagoya Institute Technology, and a commercial unit-selection system CereVoice, developed by Cereproc. Both systems have been used to mimic the voice of George W. Bush (43rd president of the United States) using freely available audio from the web. In addition we will present a hybrid system which combines both technologies. We demonstrate examples of synthetic voices created from 10, 40 and 210 minutes of randomly selected speech. We will then discuss the underlying problems associated with voice cloning using found audio, and the scalability of our solution

Techniques for efficient regular expression matching across hardware architectures

Regular expression matching is a central task for many networking and bioinformatics applications. For example, network intrusion detection systems, which perform deep packet inspection to detect malicious network activities, often encode signatures of malicious traffic through regular expressions. Similarly, several bioinformatics applications perform regular expression matching to find common patterns, called motifs, across multiple gene or protein sequences. Hardware implementations of regular expression matching engines fall into two categories: memory-based and logic-based solutions. In both cases, the design aims to maximize the processing throughput and minimize the resources requirements, either in terms of memory or of logic cells. Graphical Processing Units (GPUs) offer a highly parallel platform for memory-based implementations, while Field Programmable Gate Arrays (FPGAs) support reconfigurable, logic-based solutions. In addition, Micron Technology has recently announced its Automata Processor, a memory-based, reprogrammable hardware device. From an algorithmic standpoint, regular expression matching engines are based on finite automata, either in their non-deterministic or in their deterministic form (NFA and DFA, respectively). Micron's Automata Processor is based on a proprietary Automata Network, which extends classical NFA with counters and boolean elements. In this work, we aim to implement highly parallel memory-based and logic-based regular expression matching solutions. Our contributions are summarized as follows. First, we implemented regular expression matching on GPU. In this process, we explored compression techniques and regular expression clustering algorithms to alleviate the memory pressure of DFA-based GPU implementations. Second, we developed a parser for Automata Networks defined through Micron's Automata Network Markup Language (ANML), a XML-based high-level language designed to program the Automata Processor. Specifically, our ANML parser first maps the Automata Networks to an