Joint recovery algorithms using difference of innovations for distributed compressed sensing

Distributed compressed sensing is concerned with representing an ensemble of jointly sparse signals using as few linear measurements as possible. Two novel joint reconstruction algorithms for distributed compressed sensing are presented in this paper. These algorithms are based on the idea of using one of the signals as side information; this allows to exploit joint sparsity in a more effective way with respect to existing schemes. They provide gains in reconstruction quality, especially when the nodes acquire few measurements, so that the system is able to operate with fewer measurements than is required by other existing schemes. We show that the algorithms achieve better performance with respect to the state-of-the-art.Comment: Conference Record of the Forty Seventh Asilomar Conference on Signals, Systems and Computers (ASILOMAR), 201

Air Coupled Impact Echo Testing of Buried Concrete Pipes

Concrete pipes constitute an integral part of the buried infrastructure, and non-destructive testing (NDT) plays an important role in their maintenance effort. Impact echo (IE) is a well-established NDT technique that is widely used for the investigation of concrete structures. In this technique, the thickness (or resonant) frequency is first measured by inducing (compression) P-wave into the structure using an impact source and recording the elastic wave generated using an accelerometer. From the knowledge of P-wave velocity of the medium, the unknown thickness and subsurface defects are then established. To effectively apply this technique, the transducer should be properly coupled with the surface. However, this often becomes a difficult task due to the poor surface quality of concrete. Alternatively, instead of capturing the elastic wave with a contact-based transducer the leaky acoustic wave that accompany the elastic wave is captured with a microphone and the thickness frequency is calculated. This non-contact variation of IE is called the air-coupled IE (ACIE) and it has been shown to be effective for testing plate like concrete structures (e.g., pavements and bride decks). In this dissertation, the feasibility of ACIE for the NDT of buried concrete pipe is investigated. The investigations are conducted in two stages. First, numerical modelling is conducted to test the effectiveness in pipes and then experimental validations are conducted. A structural-acoustic coupled finite element model is created using the COMSOL Multiphysics software, and the propagation of elastic and acoustic waves in a fluid-filled concrete pipe is simulated for standalone and buried pipe. The effectiveness of ACIE is studied when a pipe is surrounded by soil. Two types of soil surrounding the pipe studied to learn more about the quality of the data that might be anticipated from ACIE technique inside the pipe. Using these models, various aspects of ACIE are studied and its performance against the conventional IE is compared. Following the numerical verifications, two laboratory tests setups are constructed with a standalone and buried reinforced concrete pipes (RCP) and ACIE is demonstrated using them. The (unknown) wall thickness is calculated in each case and the results are compared against the conventional contact-based technique. While the presence of soil caused energy losses which affected the amplitude of acoustic wave, it was enough to be detected with good signal to noise ratio. Several enhancements to improve the performance of this technique are studied. For instance, a way to improve the signal-to noise ratio of the acoustic signal is investigated using noise suppressers. For rapid implementation of technique and fast data gathering a semi-automated ACIE setup is also developed. Finally, the ability of the technique to detect several commonly occurring problems in a concrete pipe is investigated. In summary, ACIE technique shows promising results for buried pipe testing

Three-dimensional information retrieval (3DIR): A graph theoretic formulation for exploiting 3D geometry and model topology in information retrieval

The 3DIR project investigated the use of 3D visualization to formulate queries, compute the relevance of information items, and visualize search results. Workshops identified the user needs. Based on these, a graph theoretic formulation was created to inform the emerging system architecture. A prototype was developed. This enabled relationships between 3D objects to be used to widen a search. An evaluation of the prototype demonstrated that a tight coupling between text-based retrieval and 3D models could enhance information retrieval but add an extra layer of complexity

FindZebra:a search engine for rare diseases

BACKGROUND: The web has become a primary information resource about illnesses and treatments for both medical and non-medical users. Standard web search is by far the most common interface to this information. It is therefore of interest to find out how well web search engines work for diagnostic queries and what factors contribute to successes and failures. Among diseases, rare (or orphan) diseases represent an especially challenging and thus interesting class to diagnose as each is rare, diverse in symptoms and usually has scattered resources associated with it. METHODS: We design an evaluation approach for web search engines for rare disease diagnosis which includes 56 real life diagnostic cases, performance measures, information resources and guidelines for customising Google Search to this task. In addition, we introduce FindZebra, a specialized (vertical) rare disease search engine. FindZebra is powered by open source search technology and uses curated freely available online medical information. RESULTS: FindZebra outperforms Google Search in both default set-up and customised to the resources used by FindZebra. We extend FindZebra with specialized functionalities exploiting medical ontological information and UMLS medical concepts to demonstrate different ways of displaying the retrieved results to medical experts. CONCLUSIONS: Our results indicate that a specialized search engine can improve the diagnostic quality without compromising the ease of use of the currently widely popular standard web search. The proposed evaluation approach can be valuable for future development and benchmarking. The FindZebra search engine is available at http://www.findzebra.com/

Combat Training for Horse and Rider in the Early Middle Ages

The cavalry horse, tactics and training in Western Europe – the Euro-pean provinces of the Roman Empire of the West and the Frankish Empire – du-ring the Early Middle Ages (c. 500-1000) are still subject to many myths in both popular media and academic literature. Source material is admittedly thin, yet it is specific enough to allow us to correct many of these misconceptions and outright errors. The article initially summarises the current state of knowledge on the war horse of the period, by reference to the archaeological record. It then reviews the cavalry’s battlefield tactics, derives the skill level required to execute the manoeuvres described in the sources, and analyses where and how this training could have been provided. The information gleaned provides an insight into the skills and expertise neces-sary to achieve the requisite sophisticated level of horsemanship. We shall argue that these imply a considerable investment in organisational infrastructure, per-sonnel and institutional memory, which has so far not received much academic attention, and has wider implications for our view of the era

THE IMPORTANCE OF ORAL PERFORMANCE: WHAT MAKES A SUCCESSFUL PROFICIENCY-BASED FOREIGN LANGUAGE PROGRAM

Major Foreign Language (FL) programs in Indonesia, i.e. Indonesian for non-native speakers (BIPA) and English for Indonesian Speakers (EIS), have no standard of assessments on what constitutes a successful program. Some in-country BIPA programs that measure their success using Oral Proficiency Interviews (OPI) show the standard of success in the form of oral proficiency. This paper’s purpose is to argue that oral proficiency tests such as OPI is not only a good measure of learners’ communicative competence in general, but it also necessitates curriculums, methods, and activities geared toward the better level of communicative proficiency. Therefore, FL learning should emphasize oral proficiency to show a higher level of performable learning outcomes. Based on class observations as well as interviews of BIPA and EIS learners and instructors, this paper shows that lack of oral performance practices and assessments lead to achievement in the target language (TL) knowledge but not the communicative competence. Thus, if communicative competence is the goal, oral proficiency must be the main outcome of any FL programs

The Making and Remaking of Gogrial: Landscape, history and memory in South Sudan.

This thesis is a historical study of landscape in a pastoralist region of South Sudan called Gogrial. Gogrial is known in academic studies through Godfrey Lienhardt’s ethnographic research on Dinka religion, conducted there in the late 1940s. Since that time the area has suffered extensively in two civil wars. This thesis reinterprets Gogrial’s recent past, from the perspective of those who live there. It contributes to studies of African landscapes by showing how the landscape of Gogrial has been constructed and reconstructed through periods of civil war and expanding and contracting state power. It argues that transforming the landscape is both a way of mediating insecurity and a central part of local historical narratives. This thesis informs debates on how mobile populations construct landscape; it does this by focusing on how different pathways and different centres are temporally, socially and spatially constructed. It diverges from most studies of pastoralism, which stress marginalization, to show how pastoralists create their own centres. This is a local study but it is firmly situated in a wider political context, and is attentive to how the construction landscape in Gogrial has interacted with wider political transformations in South Sudan. Therefore it is also partly a study of how pastoralists engage with the state, showing how rural populations have sought to tap the state’s power, while retaining distinct moral claims on the landscape. In its broadest sense this is a study of how people live with chronic insecurity. Despite the extreme violence this region has experienced, people in Gogrial do not see their lives and their locality as defined by violence. Instead, this thesis will show how the experience of predatory states and militaries are woven into and in some cases subsumed by local versions of the past that stress different processes and different centres. This challenges much of the historiography of Sudan and South Sudan, which has presented places like Gogrial as victimized peripheries. In contrast, this thesis will explore rural agency and the creative cultural management of insecurity through making and remaking the landscape