True covariance simulation of the EUVE update filter

A covariance analysis of the performance and sensitivity of the attitude determination Extended Kalman Filter (EKF) used by the On Board Computer (OBC) of the Extreme Ultra Violet Explorer (EUVE) spacecraft is presented. The linearized dynamics and measurement equations of the error states are derived which constitute the truth model describing the real behavior of the systems involved. The design model used by the OBC EKF is then obtained by reducing the order of the truth model. The covariance matrix of the EKF which uses the reduced order model is not the correct covariance of the EKF estimation error. A true covariance analysis has to be carried out in order to evaluate the correct accuracy of the OBC generated estimates. The results of such analysis are presented which indicate both the performance and the sensitivity of the OBC EKF

Politics and form in Xenophon

Xenophon’s works are full of unexpected shifts in structure and peculiarities in tone: his narratives and arguments sometimes seem to change direction mid-flow, pointing the reader in opposite directions at once. In this chapter, I will suggest that these oddities of Xenophon’s style, which are such a distinctive feature of his writing but have proved a puzzle to scholars, can be explained in terms of the political effect of his works. For Xenophon, problems of form reveal and instantiate the political problems of his time. I argue that the disjunctive feel of Xenophon’s writing, rather than being a problem to be explained away, must be addressed as fundamental to his works’ historical significance

Amorphous procedure extraction

The procedure extraction problem is concerned with the meaning preserving formation of a procedure from a (not necessarily contiguous) selected set of statements. Previous approaches to the problem have used dependence analysis to identify the non-selected statements which must be 'promoted' (also selected) in order to preserve semantics. All previous approaches to the problem have been syntax preserving. This work shows that by allowing transformation of the program's syntax it is possible to extract both procedures and functions in an amorphous manner. That is, although the amorphous extraction process is meaning preserving it is not necessarily syntax preserving. The amorphous approach is advantageous in a variety of situations. These include when it is desirable to avoid promotion, when a value-returning function is to be extracted from a scattered set of assignments to a variable, and when side effects are present in the program from which the procedure is to be extracted

Amorphous procedure extraction

The procedure extraction problem is concerned with the meaning preserving formation of a procedure from a (not necessarily contiguous) selected set of statements. Previous approaches to the problem have used dependence analysis to identify the non-selected statements which must be 'promoted' (also selected) in order to preserve semantics. All previous approaches to the problem have been syntax preserving. This work shows that by allowing transformation of the program's syntax it is possible to extract both procedures and functions in an amorphous manner. That is, although the amorphous extraction process is meaning preserving it is not necessarily syntax preserving. The amorphous approach is advantageous in a variety of situations. These include when it is desirable to avoid promotion, when a value-returning function is to be extracted from a scattered set of assignments to a variable, and when side effects are present in the program from which the procedure is to be extracted

Maternal nutrient restriction and melatonin supplementation alter neurotransmitter pathways in bovine fetal and placental tissues

Nutrient restriction is a relatively common production insult to pregnancy in cattle. Recently, melatonin supplementation has been investigated as a possible therapeutic to rescue the negative effects of nutrient restriction. Neurotransmitters have been implicated as having negative programming effects in mouse and human pregnancies, manifested as metabolic and neurologic disorders. The role of neurotransmitters in fetal development has only begun to be understood in mice and humans. Neurotransmitters have not been analyzed in cattle, much less within the context of a compromised pregnancy. Brangus heifers were allotted to one of four treatments (ADQ-CON, RES-CON, ADQ-MEL, RES-MEL) in either Fall 2019 or Summer 2020. Cesarian sections, at day 240 of gestation, allowed for fetal and placental tissues to be collected for neurotransmitter and gene expression analysis. Alterations to neurotransmitter pathways were observed in a seasonally dependent manner. Future investigation is needed into the implications of altered neurotransmitters on post-natal life

Space Technology 5 Post-Launch Ground Attitude Estimation Experience

The Space Technology (ST)-5 satellites were launched March 22, 2006 on a Pegasus XL launch vehicle into a Sun-synchronous orbit. The three micro-satellites which constituted the ST-5 mission were kept in a formation which allowed three successive measurements taken of the Earth s magnetic field in order to study short term fluctuations of the field. The attitude of each satellite was computed on the ground using data from the science grade magnetometer as well as the miniature spinning Sun sensor (MSSS) which was the primary attitude sensor. Attitude and orbit maneuvers were performed using a single axial cold gas thruster. This paper describes the ground attitude estimation process and performance as well as anomaly resolutions

Wilkinson Microwave Anisotropy Probe (WMAP) Attitude Estimation Filter Comparison

The Wilkinson Microwave Anisotropy Probe (WMAP) spacecraft was launched in June of 2001. The sensor complement of WMAP consists of two Autonomous Star Trackers (ASTs), two Fine Sun Sensors (FSSs), and a gyro package which contains redundancy about one of the WMAP body axes. The onboard attitude estimation filter consists of an extended Kalman filter (EKF) solving for attitude and gyro bias errors which are then resolved into a spacecraft attitude quaternion and gyro bias. A pseudo-linear Kalman filter has been developed which directly estimates the spacecraft attitude quaternion, rate, and gyro bias. In this paper, the performance of the two filters is compared for the two major control modes of WMAP: inertial mode and observation mode

Women's leadership ambition in early careers

This is the author accepted manuscript. The final version is available from Edward Elgar via the DOI in this record.Assumptions are made that women leaving organizations in their late 30’s and 40’s are choosing to become stay-at-home mothers, implying that women have inherently lower career ambition than men. This, despite the fact that young women have been “overachieving” at university level, receiving more and better graded degrees than young men for several years. Extant research has tended to focus either on student perceptions of careers and aspirations or on the older age-group struggling to stay in organizational life. This chapter recounts a qualitative study of young women in sought-after graduate roles and asks: “How do women construe their ambition at early career stages in a professional services organization?” Considering social cognitive career theory and the identity fit model of career motivation, the chapter defines women’s early career identification with ambition and their struggle to maintain it in the current working environment, revealing that the psychological exit causing women to leave later in organizational life may start a decade earlier