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Africa ◽  
2021 ◽  
Vol 91 (5) ◽  
pp. 874-892
Author(s):  
Humphrey Asamoah Agyekum

AbstractGhana's post-independence era has been shaped by a series of coups and numerous attempted military interventions. While the involvement of the Ghana Armed Forces in politics has received widespread academic attention, the detrimental effects of these events on the military as an institution remain largely understudied. Using the coups of 1979 and 1981 as a point of departure, the article explores from an institutional perspective how the disruption of the everyday in the Ghanaian barracks resulted in the temporal breakdown of discipline and the collapse of military hierarchy. The article further examines the measures taken by the Provisional National Defence Council junta to rebuild and nurture hierarchy following its breakdown. It is also argued that restoration of hierarchy in the Ghanaian barracks called not only for an appeal to soldierly values, such as respect for rank and authority, but also for dramatic performances of authority and military hierarchy. The article depicts hierarchy in various settings, while exploring how the military order is expressed and lived in the current constellation. In short, the article not only illustrates a historical evolution, but also demonstrates that the maintenance of order and hierarchy in a closed institution such as the military is an ongoing and continuous negotiation process.


2021 ◽  
Author(s):  
Wen Huang ◽  
Benjamin Männel ◽  
Andreas Brack ◽  
Harald Schuh

<p>The Global Positioning System (GPS) satellite transmitter antenna phase center offsets (PCOs) in z-direction and the scale of the terrestrial reference frame are highly correlated when neither of them is constrained to an a priori value in a least-squares adjustment. The commonly used PCO values offered by the International GNSS Service (IGS) are estimated in a global adjustment by constraining the ground station coordinates to the current International Terrestrial Reference Frame (ITRF). As the scale of the ITRF is determined by other techniques, the estimated GPS z-PCOs are not independent. Consequently, the z-PCOs transfer the scale to any subsequent GNSS solution. To get a GNSS-based scale that can contribute to a future ITRF realization, two methods are proposed to determine scale-independent GPS z-PCOs. One method is based on the gravitational constraint on Low Earth Orbiters (LEOs) in an integrated processing of the GPS satellites and LEOs. The correlation coefficient between the GPS PCO-z and the scale is reduced from 0.85 to 0.3 by supplementing a 54-ground-station network with seven LEOs. The impact of individual LEOs on the estimation is discussed by including different subsets of the LEOs. The accuracy of the z-PCOs of the LEOs is very important for the accuracy of the solution. In another method, the GPS z-PCOs and the scale are determined in a GPS+Galileo processing where the PCOs of Galileo are fixed to the values calibrated on ground from the released metadata. The correlation between the GPS PCO-z and the scale is reduced to 0.13 by including the current constellation of Galileo with 24 satellites. We use the whole constellation of Galileo and the three LEOs of the Swarm mission to perform a direct comparison and cross-check of the two methods. The two methods provide mean GPS z-PCO corrections of -186±25 mm and -221±37 mm with respect to the IGS values, and +1.55±0.22 ppb (part per billion) and +1.72±0.31 ppb in the terrestrial scale with respect to the IGS14 reference frame. The results of both methods agree with each other with only small differences. Due to the larger number of Galileo observations, the Galileo-PCO-fixed method leads to more precise and stable results. In the joint processing of GPS+Galileo+Swarm in which both methods are applied, the constraint on Galileo dominates the results. We also discuss how fixing either the Galileo transmitter antenna z-PCO or the Swarm receiver antenna z-PCOs in the GPS+Galileo+Swarm processing propagates to the respective freely estimated z-PCOs of Swarm or Galileo.</p>


2021 ◽  
Vol 13 (3) ◽  
pp. 1489
Author(s):  
Martin Javornicky ◽  
Áine Macken-Walsh ◽  
Anita Naughton

International literature acknowledges benefits of the legally recognised Producer Organisations (POs). Successful leveraging of these benefits depends on two forms of cooperation: horizontal integration among the producers for more effective functioning of the POs; and vertical integration of POs with other actors in the production chain to facilitate processes of co-creation and interactive innovation. In 2016 PO legislation was first introduced in Ireland, and in 2019 Ireland’s first two beef POs emerged at a time when primary producers in the beef sector mobilised en masse, protesting against poor prices and seeking changes in supply chain relationships. Throughout this period, significant and detailed media reporting of the beef sector surrounded the protests, which takes the focus of our analysis. Building on an existing but limited literature on institutional conditions in the Irish beef industry and international accounts of factors influencing the success of POs, we analyse media coverage in order to shed light on the nature of emerging new forms of horizontal and vertical cooperation. In this regard, we focus on horizontal integration of producers into PO and associations of POs (APOs); and vertical integration of POs into Inter Branch Organisations (IBOs) and value-based supply chains (VBSCs). Our analysis shows that the media representations of the Irish beef sector evidence significant challenges to the establishment and successful operation of POs, in any form. The analysis suggests that current constellation of relations in the Irish beef sector represents an environment that is partially resistant to horizontal co-operation and significantly hostile to vertical co-operation. Interactive innovation involving different chain actors seems not to be imminent, at least in the short term, unless there are strategic public and/or private interventions introduced to support it.


2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Bofeng Li ◽  
Zhiteng Zhang ◽  
Weikai Miao ◽  
Guang’e Chen

AbstractThe establishment of the BeiDou global navigation satellite system (BDS-3) has been completed, and the current constellation can independently provide positioning service globally. BDS-3 satellites provide quad-frequency signals, which can benefit the ambiguity resolution (AR) and high-precision positioning. This paper discusses the benefits of quad-frequency observations, including the precision gain of multi-frequency high-precision positioning and the sophisticated choice of extra-wide-lane (EWL) or wide-lane (WL) combinations for instantaneous EWL/WL AR. Additionally, the performance of EWL real-time kinematic (ERTK) positioning that only uses EWL/WL combinations is investigated. The results indicate that the horizontal positioning errors of ERTK positioning using ionosphere-free (IF) EWL observations are approximately 0.5 m for the baseline of 27 km and 1 m for the baseline of 300 km. Furthermore, the positioning errors are reduced to the centimetre level if the IF EWL observations are smoothed by narrow-lane observations for a short period.


2020 ◽  
Vol 4 (4) ◽  
pp. 435-450
Author(s):  
Andreas Lutsch

AbstractThis article seeks to challenge sluggishness and wishful thinking in dealing with the issue of nuclear deterrence and to expose those tendencies to a reality check. Considering results of the latest research, the article offers methodological, conceptual, and empirical impulses to advance such an approach. On this basis, the article presents three key propositions to keep the current constellation of the European security order and its trajectories in perspective.


GPS Solutions ◽  
2020 ◽  
Vol 25 (1) ◽  
Author(s):  
Wen Huang ◽  
Benjamin Männel ◽  
Andreas Brack ◽  
Harald Schuh

Abstract The GPS satellite transmitter antenna phase center offsets (PCOs) can be estimated in a global adjustment by constraining the ground station coordinates to the current International Terrestrial Reference Frame (ITRF). Therefore, the derived PCO values rest on the terrestrial scale parameter of the frame. Consequently, the PCO values transfer this scale to any subsequent GNSS solution. A method to derive scale-independent PCOs without introducing the terrestrial scale of the frame is the prerequisite to derive an independent GNSS scale factor that can contribute to the datum definition of the next ITRF realization. By fixing the Galileo satellite transmitter antenna PCOs to the ground calibrated values from the released metadata, the GPS satellite PCOs in the z-direction (z-PCO) and a GNSS-based terrestrial scale parameter can be determined in GPS + Galileo processing. An alternative method is based on the gravitational constraint on low earth orbiters (LEOs) in the integrated processing of GPS and LEOs. We determine the GPS z-PCO and the GNSS-based scale using both methods by including the current constellation of Galileo and the three LEOs of the Swarm mission. For the first time, direct comparison and cross-check of the two methods are performed. They provide mean GPS z-PCO corrections of $$- 186 \pm 25$$ - 186 ± 25  mm and $$- 221 \pm 37$$ - 221 ± 37  mm with respect to the IGS values and $$+ 1.55 \pm 0.22$$ + 1.55 ± 0.22  ppb (parts per billion) and $$+ 1.72 \pm 0.31$$ + 1.72 ± 0.31 in the terrestrial scale with respect to the IGS14 reference frame. The results of both methods agree with each other with only small differences. Due to the larger number of Galileo observations, the Galileo-PCO-fixed method leads to more precise and stable results. In the joint processing of GPS + Galileo + Swarm in which both methods are applied, the constraint on Galileo dominates the results. We discuss and analyze how fixing either the Galileo transmitter antenna z-PCO or the Swarm receiver antenna z-PCO in the combined GPS + Galileo + Swarm processing propagates to the respective freely estimated z-PCO of Swarm and Galileo.


2019 ◽  
Vol 11 (22) ◽  
pp. 2717 ◽  
Author(s):  
David Doelling ◽  
Konstantin Khlopenkov ◽  
Conor Haney ◽  
Rajendra Bhatt ◽  
Brent Bos ◽  
...  

The Earth-viewed images acquired by the space probe OSIRIS-REx during its Earth gravity assist flyby maneuver on 22 September 2017 provided an opportunity to radiometrically calibrate the onboard NavCam imagers. Spatially-, temporally-, and angularly-matched radiances from the Earth viewing GOES-15 and DSCOVR-EPIC imagers were used as references for deriving the calibration gain of the NavCam sensors. An optimized all-sky tropical ocean ray-matching (ATO-RM) calibration approach that accounts for the spectral band differences, navigation errors, and angular geometry differences between NavCam and the reference imagers is formulated in this paper. Prior to ray-matching, the GOES-15 and EPIC pixel level radiances were mapped into the NavCam field of view. The NavCam 1 ATO-RM gain is found to be 9.874 × 10−2 Wm−2sr−1µm−1DN−1 with an uncertainty of 3.7%. The ATO-RM approach predicted an offset of 164, which is close to the true space DN of 170. The pre-launch NavCam 1 and 2 gains were compared with the ATO-RM gain and were found to be within 2.1% and 2.8%, respectively, suggesting that sensor performance is stable in space. The ATO-RM calibration was found to be consistent within 3.9% over a factor of ±2 NavCam 2 exposure times. This approach can easily be adapted to inter-calibrate other space probe cameras given the current constellation of geostationary imagers.


2019 ◽  
Vol 19 (1) ◽  
pp. 105-126
Author(s):  
Mariza Menger

This article deals with changes to the system of local and regional self-government in Croatia between 2003 and 2017. For the most part, reform efforts, excluding some positive developments with regard to the promotion of the democratic principles of governance, have not been successful. The article addresses the question of how to theoretically account for these changes. The aim is to offer an understanding of reform failure by focussing on the preceding processes. The article begins by establishing that reform efforts in the existing literature on Croatian local- and middle-level government reorganisation have predominantly been explained either by means of the rational-instrumental perspective or the power and conflict perspective. The former argues that reorganisation outcomes are a product of rational decision-makers, who in the early 1990s and afterwards sought to, for one reason or another, establish centralistic administration of public affairs. The latter, on the other hand, proposes that the current local- and middle-level government structure is a direct reflection of the power structure of the current constellation of political actors. The article goes on to suggest that, at least in part, changes made to the system can be attributed to the garbage can model of decision-making. This is due to the fact that participation in the decision-making arena throughout this period was fluid, the decision-makers’ attention scarce and their goals ambiguous, and the definitions of the problems unclear.


2018 ◽  
Vol 63 ◽  
pp. 00014
Author(s):  
Renata Pelc-Mieczkowska ◽  
Dariusz Tomaszewski ◽  
Karolina Jurgielewicz

Current constellation of global navigation satellite system (GNSS) ensures signal availability even in severe observational conditions like urban canyon or under tree canopy. However, positioning in such environment remains a challenge because obstacles can block, reflect and diffract GNSS signals which significantly affects accuracy. Those errors are strongly sight dependent and cannot be mitigated in differential positioning that is why, knowledge of the shape and spatial distribution of terrain obstacles is essential. In this paper using of airborne laser scanning (ALS) data for terrain obstacles inventory is presented and evaluated. In proposed method terrain obstacle models have been derived from ASCII ALS data file using open source QGIS with LAStools software suite and dedicated ALSObstModel plugin. Test models were developed for three geodetic control points with different environmental characteristics. For each point reference model from direct tachometry measurements have been obtained. An average error in determining the elevation of the terrain obstacles from ALS based models was 0.6° to 1.7°. This distance corresponds to 3 to 6 minutes of satellite in orbit.


2016 ◽  
Vol 16 (16) ◽  
pp. 10621-10635 ◽  
Author(s):  
Sam J. Silva ◽  
Colette L. Heald ◽  
Jeffrey A. Geddes ◽  
Kemen G. Austin ◽  
Prasad S. Kasibhatla ◽  
...  

Abstract. Over recent decades oil palm plantations have rapidly expanded across Southeast Asia (SEA). According to the United Nations, oil palm production in SEA increased by a factor of 3 from 1995 to 2010. We investigate the impacts of current (2010) and near-term future (2020) projected oil palm expansion in SEA on surface–atmosphere exchange and the resulting air quality in the region. For this purpose, we use satellite data, high-resolution land maps, and the chemical transport model GEOS-Chem. Relative to a no oil palm plantation scenario (∼ 1990), overall simulated isoprene emissions in the region increased by 13 % due to oil palm plantations in 2010 and a further 11 % in the near-term future. In addition, the expansion of palm plantations leads to local increases in ozone deposition velocities of up to 20 %. The net result of these changes is that oil palm expansion in SEA increases surface O3 by up to 3.5 ppbv over dense urban regions, and in the near-term future could rise more than 4.5 ppbv above baseline levels. Biogenic secondary organic aerosol loadings also increase by up to 1 µg m−3 due to oil palm expansion, and could increase by a further 2.5 µg m−3 in the near-term future. Our analysis indicates that while the impact of recent oil palm expansion on air quality in the region has been significant, the retrieval error and sensitivity of the current constellation of satellite measurements limit our ability to observe these impacts from space. Oil palm expansion is likely to continue to degrade air quality in the region in the coming decade and hinder efforts to achieve air quality regulations in major urban areas such as Kuala Lumpur and Singapore.


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