On the distribution of an effective channel estimator for multi-cell massive MIMO

Accurate channel estimation is of utmost importance for massive MIMO systems to provide significant improvements in spectral and energy efficiency. In this work, we present a study on the distribution of a simple but yet effective and practical channel estimator for multi-cell massive MIMO systems suffering from pilot-contamination. The proposed channel estimator performs well under moderate to aggressive pilot contamination scenarios without previous knowledge of the inter-cell large-scale channel coefficients and noise power, asymptotically approximating the performance of the linear MMSE estimator as the number of antennas increases. We prove that the distribution of the proposed channel estimator can be accurately approximated by the circularly-symmetric complex normal distribution, when the number of antennas, M, deployed at the base station is greater than 10

REXIB: Remote Experiments Interface Builder

Remote Experimentation is an educational resource that allows teachers to strengthen the practical contents of science & engineering courses. However, building up the interfaces to remote experiments is not a trivial task. Although teachers normally master the practical contents addressed by a particular remote experiment they usually lack the programming skills required to quickly build up the corresponding web interface. This paper describes the automatic generation of experiment interfaces through a web-accessible Java application. The application displays a list of existent modules and once the requested modules have been selected, it generates the code that enables the browser to display the experiment interface. The tools main advantage is enabling non-tech teachers to create their own remote experiments

Remote experimentation network - yielding an inter-university peer-to-peer e-service

The goal of this paper is to discuss the benefits and challenges of yielding an inter-continental network of remote laboratories supported and used by both European and Latin American Institutions of Higher Education. Since remote experimentation, understood as the ability to carry out real-world experiments through a simple web browser, is already a proven solution for the educational community as a supplement to on-site practical lab work (and in some cases, namely for distance learning courses, a replacement to that work), the purpose is not to discuss its technical, pedagogical, or economical strengths, but rather to raise and try to answer some questions about the underlying benefits and challenges of establishing a peer-to-peer network of remote labs. Ultimately, we regard such a network as a constructive mechanism to help students gain the working and social skills often valued by multinational/global companies, while also providing awareness of local cultural aspects

Theoretical approaches in subject information organization: an analysis of the presence of subject cataloguing and indexing matters in ISKO-Spain literature

[Resumo] O Tratamento Temático da Informação ? TTI, na Biblioteconomia e Documentação, possui natureza mediadora, pois propicia interlocução dos contextos de produção e de uso da informação por meio da análise, descrição e representação do conteúdo dos documentos para armazenamento e recuperação da informação em cujo âmbito se desenvolvem processos, instrumentos e produtos. Essa área de estudos se apresenta, teoricamente, sob três vertentes: catalogação de assunto, de matriz norte-americana, e indexação, de matriz inglesa, mais centradas nos instrumentos e produtos de TTI, e análise documental, de matriz francesa, mais voltada para os procedimentos envolvidos no TTI. Nesse contexto, e considerando que o capítulo espanhol da ISKO atua como um importante e consolidado espaço científico de discussões acadêmicas sobre o TTI, notadamente no âmbito ibero-americano, procede-se a uma análise de domínio das correntes teóricas de matriz anglo-saxônica ? Indexação e Catalogação de Assunto ? nas comunicações apresentadas nos nove congressos de ISKO-España até então realizados, para identificar sua presença, sua articulação e seus referentes teóricos como subsídio aos estudos epistemológicos em organização do conhecimento.[Abstract] Subject information organization has a capital position in the Library and Documentation field since it promotes a dialogical dimension (or sometimes a bridge) between the information production and the information use by means of set of special activities like subject analysis, description and representation in order to promote information retrieval. Such branch of studies presents can be presented by means of different theoretical approaches. In this sense, the anglo-saxon approaches ? subject cataloguing and indexing ? are more devoted to the development of indexing languages and catalogues while the French-oriented approach - analyse documentaire - denotes a bigger concern on the procedures involved. Considering that the Spanish chapter of ISKO has been acting as an important scientific in knowledge organization matters (including subject information organization) specially in the Ibero-American countries, it carries out an analysis of the presence of the mentioned Anglo-saxon approaches - subject cataloguing and indexing ? in the papers presented at the ISKO-Spain congresses already occurred in order to identify the scientific articulation degree among their theoretical referents as a subsidy to the epistemological studies in knowledge organization in Spain

A buil-in mixed-signal block observer (BIMBO) to improve observability in 1149.4 environments

This document proposes an extension to the IEEE 1149.4 test infrastructure, whereby a bank of sigma-delta first order modulators enables the simultaneous observation of several analog pins in a single component. The modulator output bit streams are shifted out and made available to an external test controller that comprises the corresponding bank of decimation filters and other decision and control logic. The architecture proposed is fully non-intrusive and may be used to support debug and test operations in mixed-signal environments

Penetrating Ureteral Trauma.

The purpose of this series is to report our experience in managing ureteral trauma, focusing on the importance of early diagnosis, correct treatment, and the impact of associated injuries on the management and morbid-mortality. From January 1994 to December 2002, 1487 laparotomies for abdominal trauma were performed and 20 patients with ureteral lesions were identified, all of them secondary to penetrating injury. Medical charts were analyzed as well as information about trauma mechanisms, diagnostic routine, treatment and outcome. All patients were men. Mean age was 27 years. The mechanisms of injury were gunshot wounds in 18 cases (90%) and stab wounds in two (10%). All penetrating abdominal injuries had primary indication of laparotomy, and neither excretory urography nor computed tomography were used in any case before surgery. The diagnosis of ureteric injury was made intra-operatively in 17 cases (85%). Two ureteral injuries (10%) were initially missed. All patients had associated injuries. The treatment was dictated by the location, extension and time necessary to identify the injury. The overall incidence of complications was 55%. The presence of shock on admission, delayed diagnosis, Abdominal Trauma Index > 25, Injury Severity Score > 25 and colon injuries were associated to a high complication rate, however, there was no statistically significant difference. There were no mortalities in this group. A high index of suspicion is required for diagnosis of ureteral injuries. A thorough exploration of all retroperitoneal hematoma after penetrating trauma should be an accurate method of diagnosis; even though it failed in 10% of our cases.33142-8, discussion 149-5

Exploring chemical compound space with a graph-based recommender system

With the availability of extensive databases of inorganic materials, data-driven approaches leveraging machine learning have gained prominence in materials science research. In this study, we propose an innovative adaptation of data-driven concepts to the mapping and exploration of chemical compound space. Recommender systems, widely utilized for suggesting items to users, employ techniques such as collaborative filtering, which rely on bipartite graphs composed of users, items, and their interactions. Building upon the Open Quantum Materials Database (OQMD), we constructed a bipartite graph where elements from the periodic table and sites within crystal structures are treated as separate entities. The relationships between them, defined by the presence of ions at specific sites and weighted according to the thermodynamic stability of the respective compounds, allowed us to generate an embedding space that contains vector representations for each ion and each site. Through the correlation of ion-site occupancy with their respective distances within the embedding space, we explored new ion-site occupancies, facilitating the discovery of novel stable compounds. Moreover, the graph's embedding space enabled a comprehensive examination of chemical similarities among elements, and a detailed analysis of local geometries of sites. To demonstrate the effectiveness and robustness of our method, we conducted a historical evaluation using different versions of the OQMD and recommended new compounds with Kagome lattices, showcasing the applicability of our approach to practical materials design

A novel methodology for the concurrent test of partial and dynamically reconfigurable SRAM-based FPGAs

This poster presents the first truly non-intrusive structural concurrent test approach, with the objective of testing partially and dynamically reconfigurable SRAM-based FPGAs without disturbing their operation. This is accomplished by using a new methodology to carry out the replication of active Configurable Logic Blocks (CLBs), i.e. CLBs that are part of an implemented function that is actually being used by the system, releasing it to be tested in a way that is completely transparent to the system

Run-time management of logic resources on reconfigurable systems

Dynamically reconfigurable systems based on partialand dynamically reconfigurable FPGAs may have theirfunctionality partially modified at run-time withoutstopping the operation of the whole system.The efficient management of the logic space availableis one of the biggest problems faced by these systems.When the sequence of reconfigurations to be performed isnot predictable, resource allocation decisions have to bemade on-line. A rearrangement may be necessary to getenough contiguous space to implement incomingfunctions, avoiding the spreading of their components andthe resulting degradation of system performance.A new software tool that helps to handle the problemsposed by the consecutive reconfiguration of the same logicspace is presented in this paper. This tool uses a novel on--line rearrangement procedure to solve fragmentationproblems and to rearrange the logic space in a waycompletely transparent to the applications currentlyrunnin

Real-time fault injection using enhanced on-chip debug infrastructures

The rapid increase in the use of microprocessor-based systems in critical areas, where failures imply risks to human lives, to the environment or to expensive equipment, significantly increased the need for dependable systems, able to detect, tolerate and eventually correct faults. The verification and validation of such systems is frequently performed via fault injection, using various forms and techniques. However, as electronic devices get smaller and more complex, controllability and observability issues, and sometimes real time constraints, make it harder to apply most conventional fault injection techniques. This paper proposes a fault injection environment and a scalable methodology to assist the execution of real-time fault injection campaigns, providing enhanced performance and capabilities. Our proposed solutions are based on the use of common and customized on-chip debug (OCD) mechanisms, present in many modern electronic devices, with the main objective of enabling the insertion of faults in microprocessor memory elements with minimum delay and intrusiveness. Different configurations were implemented starting from basic Components Off-The-Shelf (COTS) microprocessors, equipped with real-time OCD infrastructures, to improved solutions based on modified interfaces, and dedicated OCD circuitry that enhance fault injection capabilities and performance. All methodologies and configurations were evaluated and compared concerning performance gain and silicon overhead