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Until now, RTK (real-time kinematic) and NRTK (Network-based RTK) have been the most popular cm-level accurate positioning approaches based on Global Navigation Satellite System (GNSS) signals in real-time. The tropospheric delay is a major source of RTK errors, especially for medium and long baselines. This source of error is difficult to quantify due to its reliance on highly variable atmospheric humidity. In this paper, we use the NRTK approach to estimate double-differenced zenith tropospheric delays alongside ambiguities and positions based on a complete set of multi-GNSS data in a sample 6-station network in Europe. The ZTD files published by IGS were used to validate the estimated ZTDs. The results confirmed a good agreement, with an average Root Mean Squares Error (RMSE) of about 12 mm. Although multiplying the unknowns makes the mathematical model less reliable in correctly fixing integer ambiguities, adding a priori interpolated ZTD as quasi-observations can improve positioning accuracy and Integer Ambiguity Resolution (IAR) performance. In this work, weighted least-squares (WLS) were performed using the interpolation of ZTD values of near reference stations of the IGS network. When using a well-known Kriging interpolation, the weights depend on the semivariogram, and a higher network density is required to obtain the correct covariance function. Hence, we used a simple interpolation strategy, which minimized the impact of altitude variability within the network. Compared to standard RTK where ZTD is assumed to be unknown, this technique improves the positioning accuracy by about 50%. It also increased the success rate for IAR by nearly 1. [ABSTRACT FROM AUTHOR]

This article starts from the observation that most voters know relatively little about positions and plans of political parties, especially when European Union politics is concerned. One reason for this could be that the main sources for political information, party communication and mass media coverage, provide voters only little concrete information about positions and plans of political parties. We ask how concretely, respectively vaguely, political parties and mass media communicate political positions prior to the 2014 European Parliament elections. We conducted a quantitative content analysis of all European Union–related press releases from 46 national political parties and of all European Union–related articles of 14 national quality newspapers from 7 European countries 12 weeks before the 2014 European Parliament elections. Our analysis shows that press releases as well as media coverage contain more concrete political positions on European Union issues than vague political statements. Other than expected, newspaper coverage provided the public with less concrete information than political actors did. Nevertheless, countries vary with regard to the extent to which party communication or newspaper coverage contain vague statements. We cannot find empirical support that the communication of concrete political positions depends on a party's "extremity" of issue position or on the type of issue. [ABSTRACT FROM AUTHOR]

Carrier-phase inter-frequency bias (IFB) exists in GLObal NAvigation Satellite System (GLONASS) baselines when receivers of different brands are used. Those biases need to be calibrated in GLONASS data processing to derive precise fixed solutions. Consequently, the accuracy of the IFB calibration affects ambiguity fixing, and low-accuracy IFB values in the calibration will degrade the positioning results. Hitherto, at least two IFB rate value sets for various receiver brands have been given in previous studies. Some of the differences between the value sets exceed 2 mm/FN (frequency number) and the effects of those differences on ambiguity fixing have not been investigated until now. This study showed that ambiguity fixing in GLONASS single-epoch positioning is very sensitive to the accuracy of the IFB rates. Even errors of millimetres can seriously lower the empirical success rate. The short baselines from the Global Navigation Satellite System (GNSS, which includes Russian GLONASS) networks of the International GNSS Service and the Regional Reference Frame Sub-Commission for Europe were employed to obtain more accurate IFB rate estimates with the proposed two-dimensional particle filtering. Afterwards, the IFB estimates were statistically refined by the least-squares method. Experiments showed that when the refined IFB rates were used in the IFB calibration, the empirical success rates of ambiguity fixing in GLONASS single-epoch positioning were largely improved compared with the values given before, improvements such as 20·6% for a Septentrio and Leica receiver combination. [ABSTRACT FROM AUTHOR]

We present a formal model of party competition to explain differences in party ideological ambiguity. Existing works generally argue that parties are more or less ambiguous depending on whether their supporters are risk-acceptant or risk-averse. Our model explores more fully strategic choice of ambiguity by considering nonelectoral benefits to ambiguity--that is, party elite recruitment and retention. In terms of costs, we assume that all voters are risk-averse, who therefore prefer less ideological ambiguity. Explicitly considering both costs and benefits derives our hypotheses and highlights the importance of party competition--ambiguity is influenced by the proximity to a party's closest ideological competitor. An empirical analysis of twenty-eight European countries supports our hypotheses. [ABSTRACT FROM AUTHOR]

Using discursive institutionalism as an analytical framework, this article addresses how national actors build, coordinate and communicate discourses on EU defence policy (CSDP) at home. The empirical analysis is based on a comparative study of substantive and interactive discourses in France and Ireland, two contrasted cases. It demonstrates that France and Ireland frame and interpret elements of CSDP that best fit their needs, use them to promote their defence agenda in a legitimate and ‘European’ way and present CSDP as a natural continuation of their preferences. These defence agendas revolve around the preservation of France’s exceptionalism and Ireland’s neutrality. Discursive institutionalism, which methodologically sheds light on agents and institutional contexts, helps to understand the dynamics of constructive ambiguity, a discursive strategy often applied to CSDP and illustrated by these two cases. [ABSTRACT FROM PUBLISHER]

How can we explain an international agreement that appears to run counter to the declared objectives of one of the key players? This article examines the US–EU Open Skies agreement signed in 2007 and asks why Europeans accepted the agreement after having rejected a comparable version three years earlier. Theoretical approaches that explain time inconsistency in international negotiations tend to focus on reasons why states can be constrained to accept suboptimal solutions. In multi-level bargaining, principal–agent and bureaucratization theories focus on loss of control and constructivists suggest that governments can become trapped in rhetoric. This article shows that paradoxical agreements can be voluntary and explains them by showing the rationale behind multi-games that include ambiguity about the future. In particular, increasing the flexibility of the agreement allowed negotiators to escape present-day constituent pressures by remaining ambiguous and betting on shifting coalitions. [ABSTRACT FROM PUBLISHER]

This article investigates a number of conceptual and empirical issues relating to the ambiguity of the concept 'civility'. By asking what kind of problems 'civility' was a response to, it highlights the ambiguity of the concept in a long-term historical context and demonstrates this in a number of key areas for twentieth-century European history: the relationship between civility and violence, civility and the un-making of death, civility and recognition, civility and subjectivity, as well as the dynamic relationship between inclusion and exclusion that characterises the practice of civility particularly in colonial and post-colonial contexts. It then develops a number of themes highlighted by the use of 'civility' as a historical concept, arguing that contemporary meanings of the concept has to be incorporated in empirical studies. [ABSTRACT FROM AUTHOR]

Abstract: The present article discusses the relevance of studying EU political discourse in a linguistically based polyphonic perspective. The claim is that polyphony is a fruitful approach in the sense that it reveals different types of hidden interaction and thus uncovers implicit and unclear messages. Examples are taken from two speeches given by former Prime Minister Tony Blair, on Europe and European integration, speeches which can be characterised as ‘visionary speeches’. A selection of linguistic features indicating the presence of different voices in these speeches, which are formally monological, will be presented. The analysis will thus help to identify the nature of the postulated unclearness in political discourse and to make explicit the complex relationship between text and context. The theoretical framework used for analysing the speeches will be linguistic polyphony as developed in the ScaPoLine theory. [Copyright &y& Elsevier]

This essay expands upon recent scholarship that compares poststructuralist European thinkers with Kenneth Burke by comparing Derrida concept of undecidability with Burke notion of ambiguity. The article begins with an examination of the Derridean notion of undecidability followed by a review of Burke's treatment of the concept of ambiguity. The article concludes with a brief comparative discussion of undecidability and ambiguity that clarifies the differences and similarities, and suggests implications for critical analysis. [ABSTRACT FROM AUTHOR]

Forced migration studies struggles to counterbalance policy assumptions that the governance of displaced people is of a fundamentally different nature in the Global South and North. This paper contributes to a growing body of critical scholarship that questions the epistemic segregation and theoretical demarcation that reproduce such exceptionalism. It mobilizes the idea of strategic institutional ambiguity to innovatively interrogate routinely assumed differences between migration governance in the Global South and North. It juxtaposes in-depth empirical case-studies of refugee governance in Lebanon, the country with the world's highest per capita number of refugees, with a review of critical research on EUropean governance of forced and irregular migrants. This exploration demonstrates that the rationales and manifestations of the 'politics of uncertainty' that refugees are subjected to in Lebanon closely mirror those of the 'politics of abandonment' and 'exhaustion' that migrants face in EUrope. Under both regimes, strategic forms of ambiguity operate to spatially and temporally marginalize refugees and render them controllable, exploitable, and deportable. • In Lebanon, state authorities govern Syrian refugees through partially strategic forms of non-policy and institutional ambiguity. • In EUrope, migration governance practices center on imposing informality, liminality, and exceptionalism. • This is done by creating and upholding convenient policy ambivalence and implementation gaps. • This highlights important parallels between the governance of forced displacement in the Global South and North. [ABSTRACT FROM AUTHOR]

GNSS-based Precise Orbit Determination (POD) of Low Earth Orbiters (LEOs) has nowadays become a standard application for high-quality GNSS products as provided by the IGS, or its individual analysis centers. For many LEOs, e.g., for altimetry missions, the centimeter absolute orbit precision and accuracy achieved by carrier phase-based GNSS positioning is mandatory and could hardly be obtained by other tracking data.Fixing the carrier phase ambiguities to their integer values has been known to inherently stabilize solutions for parameters since a long time and has been confirmed in many applications. In case of LEO POD, this has been shown extensively, e.g., by double difference processing of space or space-ground baselines for relative POD, allowing for ambiguity resolution without using any dedicated GNSS products in addition. While the processing of space baselines is feasible only for constellations of LEOs in formation flight (e.g., GRACE), the processing of space-ground baselines is very costly in computational terms if all correlations shall be modeled correctly.Single-receiver or undifferenced ambiguity fixing in Precise Point Positioning processing requires the knowledge of GNSS satellite phase biases which cancel out in forming baselines. Such products have been provided by the CNES/CLS (Centre National d'Etudes Spatiales/Collecte Localisation Satellites) analysis center of the IGS since a few years. Recently, the Center for Orbit Determination in Europe (CODE) IGS analysis center has established the generation of a high-quality signal-specific phase bias product and a fully consistent ambiguity-fixed clock product within its rapid and final IGS-related processing.On the basis of these new CODE bias and clock products, we demonstrate the performance of single-receiver ambiguity resolution for the absolute POD of the GRACE, Sentinel-3, and Swarm LEOs and compare it to results obtained by double-difference processing including ambiguity fixing. The impact of ambiguity fixing on orbit quality is assessed in terms of standard POD quality measures, independent Satellite Laser Ranging (SLR) validation, and, in case of GRACE, ultra-precise inter-satellite K-band ranging validation. [ABSTRACT FROM AUTHOR]