Synchronising coherent networked radar using low-cost GPS-disciplined oscillators

This text evaluates the feasibility of synchronising coherent, pulsed-Doppler, networked, radars with carrier frequencies of a few gigahertz and moderate bandwidths of tens of megahertz across short baselines of a few kilometres using low-cost quartz GPSDOs based on one-way GPS time transfer. It further assesses the use of line-of-sight (LOS) phase compensation, where the direct sidelobe breakthrough is used as the phase reference, to improve the GPS-disciplined oscillator (GPSDO) synchronised bistatic Doppler performance. Coherent bistatic, multistatic, and networked radars require accurate time, frequency, and phase synchronisation. Global positioning system (GPS) synchronisation is precise, low-cost, passive and covert, and appears well-suited to synchronise networked radar. However, very few published examples exist. An imperfectly synchronised bistatic transmitter-receiver is modelled. Measures and plots are developed enabling the rapid selection of appropriate synchronisation technologies. Three low-cost, open, versatile, and extensible, quartz-based GPSDOs are designed and calibrated at zero-baselines. These GPSDOs are uniquely capable of acquiring phase-lock four times faster than conventional phase-locked loops (PLLs) and a new time synchronisation mechanism enables low-jitter sub-10 ns oneway GPS time synchronisation. In collaboration with University College London, UK, the 2.4 GHz coherent pulsed-Doppler networked radar, called NetRAD, is synchronised using the University of Cape Town developed GPSDOs. This resulted in the first published example of pulsed-Doppler phase synchronisation using GPS. A tri-static experiment is set up in Simon’s Bay, South Africa, with a maximum baseline of 2.3 km. The Roman Rock lighthouse was used as a static target to simultaneously assess the range, frequency, phase, and Doppler performance of the monostatic, bistatic, and LOS phase corrected bistatic returns. The real-world results compare well to that predicted by the earlier developed bistatic model and zero-baseline calibrations. GPS timing limits the radar bandwidth to less than 37.5 MHz when it is required to synchronise to within the range resolution. Low-cost quartz GPSDOs offer adequate frequency synchronisation to ensure a target radial velocity accuracy of better than 1 km/h and frequency drift of less than the Doppler resolution over integration periods of one second or less. LOS phase compensation, when used in combination with low-cost GPSDOs, results in near monostatic pulsed-Doppler performance with a subclutter visibility improvement of about 30 dB

Latitudinal differences in the amplitude of the OAE-2 carbon isotopic excursion: pCO2 and paleoproductivity [Discussion paper]

A complete, well-preserved record of the Cenomanian/Turonian (C/T) Oceanic Anoxic Event 2 (OAE-2) was recovered from Demerara Rise in the southern North Atlantic Ocean (ODP site 1260). Across this interval, we determined changes in the stable carbon isotopic composition of sulfur-bound phytane (δ13Cphytane, a biomarker for photosynthetic algae. The δ13Cphytane record shows a positive excursion at the onset of the OAE-2 interval, with an unusually large amplitude (~7 ‰) compared to existing C/T proto-North Atlantic δ13Cphytane records (3–6 ‰). Overall, the amplitude of the excursion of δ13Cphytane decreases with latitude. Using reconstructed sea surface temperature (SST) gradients for the proto-North Atlantic, we investigated environmental factors influencing the latitudinal δ13Cphytane gradient. The observed gradient is best explained by high productivity at DSDP Site 367 and Tarfaya basin before OAE-2, which changed in overall high productivity throughout the proto-North Atlantic during OAE-2. During OAE-2, productivity at site 1260 and 603B was thus more comparable to the mid-latitude sites. Using these constraints as well as the SST and δ13Cphytane-records from Site 1260, we subsequently reconstructed pCO2 levels across the OAE-2 interval. Accordingly, pCO2 decreased from ca. 1750 to 900 ppm during OAE-2, consistent with enhanced organic matter burial resulting in lowering pCO2. Whereas the onset of OAE-2 coincided with increased pCO2, in line with a volcanic trigger for this event, the observed cooling within OAE-2 probably resulted from CO2 sequestration in black shales outcompeting CO2 input into the atmosphere. Together these results show that the ice-free Cretaceous world was sensitive to changes in pCO2 related to perturbations of the global carbon cycle

A NEW GEOMETRIC MODEL AND METHODOLOGY FOR UNDERSTANDING PARSIMONIOUS SEVENTH-SONORITY PITCH-CLASS SPACE

Parsimonious voice leading is a term, first used by Richard Cohn, to describe non-diatonic motion among triads that will preserve as many common tones as possible, while limiting the distance traveled by the voice that does move to a tone or, better yet, a semitone. Some scholars have applied these principles to seventh chords, laying the groundwork for this study, which strives toward a reasonably comprehensive, usable model for musical analysis. Rather than emphasizing mathematical proofs, as a number of approaches have done, this study relies on two- and three-dimensional geometric visualizations and spatial analogies to describe pitch-class and harmonic relationships. These geometric realizations are based on the organization of the neo-Riemannian Tonnetz, but they expand and apply the organizational principles of the Tonnetz to seventh sonorities. It allows for the descriptive “mapping” or prescriptive “navigation” of harmonic paths through a defined space. The viability of the theoretical model is examined in analyses of passages from the repertoire of Frédéric Chopin. These passages exhibit a harmonic syntax that is often difficult to analyze as anything other than “tonally unstable” or “transitional.” This study seeks to analyze these passages in terms of what they are, rather than what they are not

Tests of arc lamps

Citation: Jacobus, C. R. and Young, S. S. Tests of arc lamps. Senior thesis, Kansas State Agricultural College, 1908.Introduction: In the year 1800 Volta observed the spark, in which year, also, Davy discovered the particularly bright spark between charcoal points separated in air or in liquids, which pressure from 150 elements. In 1808 Davy with a battery of 2000 elements exhibited the first true arc, a flame of about four inches long, before the Royal Institution at London, England

The management of a policy implementation project: the disastrous Gauteng Mental Health Marathon Project

The widely reported disastrous Gauteng Mental Health Marathon Project caused the deaths of about 144 vulnerable individuals. The purpose of this contribution is to make sense of the latter by providing a chronological reconstruction of the main series of events. This is followed by a selection of the most appropriate theoretical lenses for identifying those implausible events and for comprehensively redrafting this narrative to gain understanding. The sensemaking approach was selected for the simplicity in guiding the sense-maker with naïve questions through the messy field of discrepancies. With this disastrous policy implementation project study in mind, we have asked: “Why do policy implementation projects become disastrous?” and “How can policy implementation projects be vision aligned?” As this specific case of policy implementation projects has been intensively and widely scrutinised in the public domain, we have relied nearly exclusively on publicly available material. In doing so, researchers acknowledge that there are numerous other perspectives and stories that we have not sourced and analysed. For the purpose of this sensemaking process, three interrelated lenses were used, namely the policy regime lens, the policy commitment lens and the political-administrative interface lens. However, we acknowledge that our selection and use of these theoretical lenses are not entirely exhaustive and adequate. This study has found that the all-inclusive national healthcare policy regime has been attenuated by the Gauteng Department of Health (GDoH) to the exclusion of the national policy intent and the wide variety of legitimate healthcare stakeholders. We have argued that the behaviour of the GDoH in this saga can be attributed, inter alia, to the situational theory of policy commitment. Furthermore, the study found that the relationship between the political office bearer and the Head of Department (HoD) in our case, was not at all equal and complementary; the Member of the Executive Council (MEC) overstepped in the sphere of public administration, while the HoD did not sufficiently execute his legal authority as accounting officer. Lastly, it was found that the operational project management process focused almost exclusively on removing the mental healthcare users from the Life Healthcare Esidimeni facilities before 30 June 2016, without evidence that those facilities to which they were transferred, would constitute the envisaged improved mental healthcare for them. This case study has shown that it is possible through retrospective sensemaking to creatively rectify the errors of the past and replace them with an envisaged future storyline.European UnionPublic Administration and Managemen

Experimental study of the 11B(p,3α)γ^{11}\text{B}(p,3\alpha)\gamma reaction at Ep=0.5−2.7E_p = 0.5-2.7 MeV

Our understanding of the low-lying resonance structure in $^{12}$C remains incomplete. We have used the $^{11}\text{B}(p,3\alpha)\gamma$ reaction at proton energies of $E_p=0.5-2.7$ MeV as a selective probe of the excitation region above the $3\alpha$ threshold in $^{12}$C. Transitions to individual levels in $^{12}$C were identified by measuring the 3$\alpha$ final state with a compact array of charged-particle detectors. Previously identified transitions to narrow levels were confirmed and new transitions to broader levels were observed for the first time. Here, we report cross sections, deduce partial $\gamma$-decay widths and discuss the relative importance of direct and resonant capture mechanisms.Comment: 9 pages, 7 figures, 5 tables; added details on data analysi

Directional Gaussian spatial processes for South African wind data

Accurate wind pattern modelling is crucial for various applications, including renewable energy, agriculture, and climate adaptation. In this paper, we introduce the wrapped Gaussian spatial process (WGSP), as well as the projected Gaussian spatial process (PGSP) custom-tailored for South Africa's intricate wind behaviour. Unlike conventional models struggling with the circular nature of wind direction, the WGSP and PGSP adeptly incorporate circular statistics to address this challenge. Leveraging historical data sourced from meteorological stations throughout South Africa, the WGSP and PGSP significantly increase predictive accuracy while capturing the nuanced spatial dependencies inherent to wind patterns. The superiority of the PGSP model in capturing the structural characteristics of the South African wind data is evident. As opposed to the PGSP, the WGSP model is computationally less demanding, allows for the use of less informative priors, and its parameters are more easily interpretable. The implications of this study are far-reaching, offering potential benefits ranging from the optimisation of renewable energy systems to the informed decision-making in agriculture and climate adaptation strategies. The WGSP and PGSP emerge as robust and invaluable tools, facilitating precise modelling of wind patterns within the dynamic context of South Africa.Comment: 9 pages, 9 Figures, conference proceedings pape

Hamiltonian discontinuous Galerkin FEM for linear, rotating incompressible Euler equations: inertial waves

A discontinuous Galerkin finite element method (DGFEM) has been developed and tested for the linear, three-dimensional, rotating incompressible Euler equations. These equations admit complicated wave solutions, which poses numerical challenges. These challenges concern: (i) discretisation of a divergence-free velocity field; (ii) discretisation of geostrophic boundary conditions combined with no-normal flow at solid walls; (iii) discretisation of the conserved, Hamiltonian dynamics of the inertial-waves; and, (iv) large-scale computational demands owing to the three-dimensional nature of inertial-wave dynamics and possibly its narrow zones of chaotic attraction. These issues have been resolved, for example: (i) by employing Dirac’s method of constrained Hamiltonian dynamics to our DGFEM for linear, compressible flows, thus enforcing the incompressibility constraints; (ii) by enforcing no-normal flow at solid walls in a weak form and geostrophic tangential flow along the wall; and, (iii) by applying a symplectic time discretisation. We compared our simulations with exact solutions of three-dimensional incompressible flows, in (non) rotating periodic and partly periodic cuboids (Poincaré waves). Additional verifications concerned semi-analytical eigenmode solutions in rotating cuboids with solid walls. Finally, a simulation in a tilted rotating tank, yielding more complicated wave dynamics, demonstrates the potential of our new method

Penerapan Metode Numbered Heads Together (Nht) Dilengkapi Lingkaran Buffer Untuk Meningkatkan Motivasi Dan Prestasi Belajar Siswa Pada Materi Larutan Penyangga Kelas XI IPA 4 Sman 2 Karanganyar Tahun Pelajaran 2012/2013

Penelitian ini bertujuan untuk mengetahui apakah: 1) penerapan Numbered Head Together (NHT) disertai lingkaran buffer dapat meningkatkan motivasi belajar pada materi pokok larutan penyangga, 2) penerapan Numbered Head Together (NHT) disertai lingkaran buffer dapat meningkatkan prestasi belajar pada materi pokok larutan penyangga. Penelitian ini adalah penelitian tindakan kelas yang mengimplementasikan dua siklus. Populasi dalam penelitian ini adalah siswa kelas XI IPA 4 SMA Negeri 2 Karanganyar tahun pelajaran 2012/ 2013. Data penelitian yang diambil berupa prestasi belajar kognitif, afektif, motivasi dan psikomotor. Pengumpulan data dilakukan melalui observasi, tes, angket, wawancara, dan dokumentasi. Teknik analisis data yang digunakan adalah analisis deskriptif kualitatif. Dari hasil penelitian dan analisis yang telah dilakukan diperoleh: 1) penerapan Numbered Head Together (NHT) disertai lingkaran buffer dapat meningkatkan motivasi belajar pada materi pokok larutan penyangga. Pada siklus I presentase motivasi sebesar 76,91 % yang kemudian meningkat pada siklus II menjadi 78,95%. 2) penerapan Numbered Head Together (NHT) disertai lingkaran buffer dapat meningkatkan prestasi belajar pada materi pokok larutan penyangga. Presentase ketuntasan belajar siswa meningkat dari 28,57% pada siklus I menjadi 62,86 % pada siklus II. Untuk hasil belajar afektif menunjukkan peningkatan ketercapaian rata-rata indikator dari 75,43 % pada siklus I menjadi 76,31 % pada siklus II dan dari segi psikomotor, ketercapaian rata-rata indikator adalah 69,24%