An integrated estimation/guidance approach for seeker-less interceptors

This paper addresses the problem of intercepting highly maneuverable threats using seeker-less interceptors that operate in the command guidance mode. These systems are more prone to estimation errors than standard seeker-based systems. In this paper, an integrated estimation/guidance (IEG) algorithm, which combines interactive multiple model (IMM) estimator with differential game guidance law (DGL), is proposed for seeker-less interception. In this interception scenario, the target performs an evasive bang-bang maneuver, while the sensor has noisy measurements and the interceptor is subject to acceleration bound. The IMM serves as a basis for the synthesis of efficient filters for tracking maneuvering targets and reducing estimation errors. The proposed game-based guidance law for two-dimensional interception, later extended to three-dimensional interception scenarios, is used to improve the endgame performance of the command-guided seeker-less interceptor. The IMM scheme and an optimal selection of filters, to cater to various maneuvers that are expected during the endgame, are also described. Furthermore, a chatter removal algorithm is introduced, thus modifying the differential game guidance law (modified DGL). A comparison between modified DGL guidance law and conventional proportional navigation guidance law demonstrates significant improvement in miss distance in a pursuer-evader scenario. Simulation results are also presented for varying flight path angle errors. A numerical study is provided which demonstrates the performance of the combined interactive multiple model with game-based guidance law (IMM/DGL). Simulation study is also carried out for combined IMM and modified DGL (IMM/modified DGL) which exhibits the superior performance and viability of the algorithm reducing the chattering phenomenon. The results are illustrated by an extensive Monte Carlo simulation study in the presence of estimation errors.

Breaking Down and Breaking Out: Beckett’s ‘Absolute Liminality’ in the Third Age of Capitalist Traumas

Fundação para a Ciência e a Tecnologia (FCT), Fundação Millennium bcp

Surgimiento y consolidación de la Nueva Ultraderecha europea a largo plazo, bajo el marco de la Unión Europea

El tema de investigación se relaciona con la disciplina, ya que resulta imprescindible el estudio sobre la posibilidad y viabilidad que tienen los gobiernos de Nueva Derecha, en un proceso de integración tan importante a nivel político, comercial, económico y social como la Unión Europea.

Estrategia de intervención militar de Estados Unidos en Medio Oriente: dinámicas y consecuencias del uso de drones en Yemen y Pakistán entre 2009 a 2013

Este es un estudio sobre la estrategia de guerra estadounidense en Medio Oriente basada en el uso sistemático de drones durante el periodo comprendido entre 2009 y 2013. Se busca explicar de qué manera puede considerarse el uso de este tipo de armamento como una práctica basada en la proyección de poder sin mayor vulnerabilidad. Los casos de Pakistán y Yemen son abordados, ya que evidencian las características de las operaciones selectivas por las que ha abogado el Presidente Obama. El estudio se inscribe dentro del realismo ofensivo, haciendo también referencia a sus limitaciones explicativas. Empero, se afirma que las dinámicas y consecuencias de la utilización de drones son intrínsecas a la necesidad estadounidense de combatir actores no estatales mediante prácticas que garanticen su seguridad y pretensiones hegemónicas a pesar de las implicaciones políticas , legales y sociales en las que puede incurrir.

Into the silence of the objects : analyzing Samuel Beckett’s nothingness

Os objetos têm sempre desempenhado um papel fundamental nas nossas vidas, pela forma como eles, passivamente, fazem-nos companhia e transmitem tacitamente a sua quietude inata. Contudo, o que acontece quando os objetos se tornam uma presença tão poderosa que, como resultado, dominam a vida das pessoas? Noutras palavras, o que é que acontece quando os objetos sobrecarregam as pessoas com as suas potentes (falando literalmente, sempre lá) presenças? No silêncio dos objetos há um lugar onde nos tornamos conscientes da nossa insignificância, da nossa crise de identidade,ansiedade de linguagem e entorpecimento. Mas nas peças Endgame e Act without Words I de Samuel Beckett, o dramaturgo gradualmente capta a inutilidade da vida das personagens principais e a transformação das suas mentes e corpos numa coleção de objetos arquivados. Sem interagir com outras pessoas e por se autoencarcerarem estas personagens de Beckett esquecem-se o que é ser humano e tornam-se «uma não-coisa, nada». Pode haver um facto perturbador nesta realização, e, sem dúvida, até mesmo uma infeliz aliteração; mesmo assim, o que é ainda mais chocante é que estas personagens são paradigmáticas em relação ao que significa ter pisado uma aniquilação prematura ontológica e existencial. Estas são agora objetos abandonados entre outros objetos, uma espécie de coleção ineficaz. Com base nestes argumentos, este ensaio mostra uma tremenda influência de Beckett no desenvolvimento da teoria da descarnalizaçao e da desmaterialização do corpo e mente do povo, culminando na revolução tecnológica onde queremos ser empilhados dentro de incontáveis arquivos de computador. O principal argumento propõe uma reflexão sobre como podemos pôr em perigo a nossa sofisticação emocional e social, jogando este complicado «jogo» digital.

Data assurance in opaque computations

The chess endgame is increasingly being seen through the lens of, and therefore effectively defined by, a data ‘model’ of itself. It is vital that such models are clearly faithful to the reality they purport to represent. This paper examines that issue and systems engineering responses to it, using the chess endgame as the exemplar scenario. A structured survey has been carried out of the intrinsic challenges and complexity of creating endgame data by reviewing the past pattern of errors during work in progress, surfacing in publications and occurring after the data was generated. Specific measures are proposed to counter observed classes of error-risk, including a preliminary survey of techniques for using state-of-the-art verification tools to generate EGTs that are correct by construction. The approach may be applied generically beyond the game domain.

6-man chess and zugzwangs

With 6-man Chess essentially solved, the available 6-man Endgame Tables (EGTs) have been scanned for zugzwang positions where, unusually, having the move is a disadvantage. Review statistics together with some highlights and positions are provided here: the complete information is available on the ICGA website. An outcome of the review is the observation that the definition of zugzwang should be revisited, if only because the presence of en passant capture moves gives rise to three new, asymmetric types of zugzwang.

6-man chess solved

Eugene Nalimov has completed the computation of a set of endgame tables for 6-man chess, and independently, Marc Bourzutschky has completed tables for 3-3 chess and for 4-2 chess where Black is not just ‘KP’. The ICGA salutes both achievements and looks ahead.

Chess endgames: 6-man data and strategy

While Nalimov’s endgame tables for Western Chess are the most used today, their Depth-to-Mate metric is not the most efficient or effective in use. The authors have developed and used new programs to create tables to alternative metrics and recommend better strategies for endgame play.

Chess endgames: data and strategy

While Nalimov’s endgame tables for Western Chess are the most used today, their Depth-to-Mate metric is not the only one and not the most effective in use. The authors have developed and used new programs to create tables to alternative metrics and recommend better strategies for endgame play.

Ken Thompson's 6-man Tables

Ken Thompson recently communicated some results mined from his set of 64 6-man endgame tables. These list some positions of interest, namely, mutual zugzwangs and those of maximum depth. The results have been analysed by the authors and found to be identical or compatible with the available or published findings of Karrer, Nalimov, Stiller and Wirth.

KQQKQQ and the Kasparov-World Game

The 1999 Kasparov-World game for the first time enabled anyone to join a team playing against a World Chess Champion via the web. It included a surprise in the opening, complex middle-game strategy and a deep ending. As the game headed for its mysterious finale, the World Team re-quested a KQQKQQ endgame table and was provided with two by the authors. This paper describes their work, compares the methods used, examines the issues raised and summarises the concepts involved for the benefit of future workers in the endgame field. It also notes the contribution of this endgame to chess itself.

Strategies for Constrained Optimisation

The latest 6-man chess endgame results confirm that there are many deep forced mates beyond the 50-move rule. Players with potential wins near this limit naturally want to avoid a claim for a draw: optimal play to current metrics does not guarantee feasible wins or maximise the chances of winning against fallible opposition. A new metric and further strategies are defined which support players’ aspirations and improve their prospects of securing wins in the context of a k-move rule.

Chess Endgames and Neural Networks

The existence of endgame databases challenges us to extract higher-grade information and knowledge from their basic data content. Chess players, for example, would like simple and usable endgame theories if such holy grail exists: endgame experts would like to provide such insights and be inspired by computers to do so. Here, we investigate the use of artificial neural networks (NNs) to mine these databases and we report on a first use of NNs on KPK. The results encourage us to suggest further work on chess applications of neural networks and other data-mining techniques.

3-5-man chess: Maximals and mzugs

This article reports the combined results of several initiatives in creating and surveying complete suites of endgame tables (EGTs) to the Depth to Mate (DTM) and Depth to Conversion (DTC) metrics. Data on percentage results, maximals and mutual zugzwangs, mzugs, has been filed and made available on the web, as have the DTM EGTs.