Venus gravity: Summary and coming events

The first significant dataset to provide local measures of venusian gravity field variations was that acquired from the Pioneer Venus Orbiter (PVO) during the 1979-1981 period. These observations were S-band Doppler radio signals from the orbiting spacecraft received at Earth-based tracking stations. Early reductions of these data were performed using two quite different techniques. Estimates of the classical spherical harmonics were made to various degrees and orders up to 10. At that time, solutions of much higher degree and order were very difficult due to computer limitations. These reductions, because of low degree and order, revealed only the most prominent features with poor spatial resolution and very reduced peak amplitudes

Closed-form solution of decomposable stochastic models

Markov and semi-Markov processes are increasingly being used in the modeling of complex reconfigurable systems (fault tolerant computers). The estimation of the reliability (or some measure of performance) of the system reduces to solving the process for its state probabilities. Such a model may exhibit numerous states and complicated transition distributions, contributing to an expensive and numerically delicate solution procedure. Thus, when a system exhibits a decomposition property, either structurally (autonomous subsystems), or behaviorally (component failure versus reconfiguration), it is desirable to exploit this decomposition in the reliability calculation. In interesting cases there can be failure states which arise from non-failure states of the subsystems. Equations are presented which allow the computation of failure probabilities of the total (combined) model without requiring a complete solution of the combined model. This material is presented within the context of closed-form functional representation of probabilities as utilized in the Symbolic Hierarchical Automated Reliability and Performance Evaluator (SHARPE) tool. The techniques adopted enable one to compute such probability functions for a much wider class of systems at a reduced computational cost. Several examples show how the method is used, especially in enhancing the versatility of the SHARPE tool

The maximal operator of a normal Ornstein--Uhlenbeck semigroup is of weak type (1,1)

Consider a normal Ornstein\u2013Uhlenbeck semigroup in R^n, whose co- variance is given by a positive definite matrix. The drift matrix is assumed to have eigenvalues only in the left half-plane. We prove that the associated maximal operator is of weak type (1, 1) with respect to the invariant measure. This extends earlier work by G. Mauceri and L. Noselli. The proof goes via the special case where the matrix defining the covariance is I and the drift matrix is diagonal

Lunar orbiter data analysis

Large Doppler residuals near pericynthion found in lunar orbiter tracking dat

Diving: using fiction narrative and intermedial assemblage to understand family histories in colonial India between 1933-1947

This practice-based research project investigates how narrative fiction, using intermedial and narratological methodologies, can be constructed in such as way as to reflect upon and understand the power relations generated within a colonial family at a particular moment in the British colonial past in India between 1933-47. My research practice, Diving, presents a series of multimedia assemblages, which recount a fictional story viewed from multiple perspectives and are played out by different dramatic characters, informed and inferred from scholarly research on domestic servants and other cultural sources, such as childhood colonial memoirs, films and literature. Some of these fictional characters, such as the colonists’ daughter, Wendy, are based on my own personal family archive. For other characters, such the ayah or nanny, Ayisha, a first-hand account is almost invisible in the historiography and archive. Diving utilises three configurations that allow the possibility to explore and amplify a multiplicity of narratives in order to uncover, in an open-ended mode of viewer reception, both different histories and, in part, hidden histories. The resulting partial and fragmented narrative nonetheless speaks to a research method that tries to decentre the dominant colonial discourse and perspective. These configurations comprise firstly, a theatrical performance combining live acting with a video projection featuring a mix of live footage from the performance and pre-recorded sequences; secondly, a single-channel film that includes multi-perspective split-screen video sequences; and thirdly, two multi-channel moving image installations for gallery exhibitions. As a method of enquiry, the process of experimenting with and testing out these three different configurations of the intermedial assemblages that frame the fictionalisation of the colonial family story set in India at the cusp of independence, has allowed for different readings by the audience, and different voices and experiences to be represented. My enquiry is underpinned by the theoretical framework of Monika Fludernik’s ‘natural narratology’, an experiential approach to the narrativisation of media, which incorporates the exploration of the subjective experiences of characters within fictional drama