Active spacecraft potential control system selection for the Jupiter orbiter with probe mission

It is shown that the high flux of energetic plasma electrons and the reduced photoemission rate in the Jovian environment can result in the spacecraft developing a large negative potential. The effects of the electric fields produced by this charging phenomenon are discussed in terms of spacecraft integrity as well as charged particle and fields measurements. The primary area of concern is shown to be the interaction of the electric fields with the measuring devices on the spacecraft. The need for controlling the potential of the spacecraft is identified, and a system capable of active control of the spacecraft potential in the Jupiter environment is proposed. The desirability of using this system to vary the spacecraft potential relative to the ambient plasma potential is also discussed. Various charged particle release devices are identified as potential candidates for use with the spacecraft potential control system. These devices are evaluated and compared on the basis of system mass, power consumption, and system complexity and reliability

TEN COMMANDMENTS FOR AGRICULTURAL ECONOMICS (AND PERHAPS OTHER) ADMINISTRATORS

There is some justification for the impression that agricultural economics has entered an era of relatively greater budget stress than that of the recent past. However, optimal strategies for sustaining or enhancing departmental productivity in research, teaching and extension are invariant to the budget level. These "strategies" are discussed in the form of "ten commandments" to department heads.Teaching/Communication/Extension/Profession,

Endurance test of a 30-CM-diameter engineering model ion thruster. Task 12: Investigation of thin-film erosion monitors for ion thrusters

An investigation of short term measurement techniques for predicting the wearout of ion thrusters resulting from sputter erosion damage is described. The previously established laminar thin film techniques to provide high precision erosion rate data. However, the erosion rates obtained using this technique are generally substantially higher than those obtained during long term endurance tests (by virtue of the as deposited nature of the thin films), so that the results must be interpreted in a relative sense. Absolute measurements can be performed using a new masked substrate arrangement which was developed during this study. This new technique provides a means for estimating the lifetimes of critical discharge chamber components based on direct measurements of sputter erosion depths obtained during short duration (10 hour) tests. The method enables the effects on lifetime of thruster design and operating parameters to be inferred without the investment of the time and capital required to conduct long term (1000 hour) endurance tests. Results obtained using the direct measurement technique are shown to agree with sputter erosion depths calculated for the plasma conditions of the test and also with lifetest results. The direct measurement approach is shown to be applicable to both mercury and argon discharge plasma environments and should be useful in estimating the lifetimes of inert gas and extended performance mercury ion thrusters presently under development

IRRIGATED AGRICULTURE AND THE GREAT PLAINS: PROBLEMS AND POLICY ALTERNATIVES

Resource /Energy Economics and Policy,

On the continuity of separately continuous bihomomorphisms

Separately continuous bihomomorphisms on a product of convergence or topological groups occur with great frequency. Of course, in general, these need not be jointly continuous. In this paper, we exhibit some results of Banach-Steinhaus type and use these to derive joint continuity from separate continuity. The setting of convergence groups offers two advantages. First, the continuous convergence structure is a powerful tool in many duality arguments. Second, local compactness and first countability, the usual requirements for joint continuity, are available in much greater abundance for convergence groups

Looking for Mary Webb: Part one - Creating a lost diary; Part two - A single violet: the lost diaries of Mary Webb

This practice-led PhD in Creative Writing consists of an historical, biographical novel called A Single Violet, and a critical commentary, Looking for Mary Webb. The novel is infused with nature writing and written in the form of a diary. The Shropshire writer Mary Webb (1881 -1927) published novels, essays and poems in the early twentieth century that explored folklore and the sacred qualities of nature. My novel sets out to create ‘a living, breathing, fictional Mary Webb’ through the imagined recreation of her diaries. Although Webb did not receive the attention she strived for in her lifetime, she received posthumous success during the idealisation of rural England of the 1930s, and in the 1980s as Virago Press reintroduced her work to a new readership. Since then, Webb has gone largely forgotten and unstudied, and very few personal papers survive in the archives. Her husband explained that the papers were burned to heat the house when the couple were too poor to pay for fuel, adding ‘they made a splendid fire’. Taking inspiration from the life and work of Webb, A Single Violet uses in-depth research and imagination to fill the deep lacuna in the record. The critical commentary Looking for Mary Webb explores the challenges encountered in writing the diary, thereby contributing to the reflexive element of Creative Writing research. It examines the difficulties of researching Webb — the gaps in the record, the problems of tracing character through biographies, and the barriers to contemporary reception of her work. It examines challenges of writing in the diary form — how to identify the reader of a diary and write for them, whilst retaining the illusion of privacy, as well as how to write a piece which is authentic in its daily detail whilst still being engaging to the reader. The diaries of Virginia Woolf, Mary Butts, Sylvia Townsend Warner and Joe Orton and the critical work of Jennifer Sinor, Elizabeth Podnieks, and Judy Simons are used to identify how reading other writers’ diaries helped to shape this fictional one. It considers the layering process used in writing the diary — how to balance factual evidence with fictional details, how to create a character the reader can empathise with, and how nature writing became the lens though which A Single Violet was written. This analysis references the work of Charles Palliser and Hilary Mantel, as well as Webb’s own coterie of biographers including Dr. Gladys Mary Coles and Dorothy Wrenn. The process of finding Webb’s writing voice is appraised alongside examination of the practicalities of writing nature in twenty-first century London

Auditor independence and audit risk: a reconceptualisation

The principles-based U.K. regulatory framework for auditor independence (Chartered Accountants Joint Ethics Committee 1996), which was adopted in 1997, identifies threats to independence in fact, independence in appearance, and the safeguards that control these threats. These principles are incorporated in the International Federation of Accountants (IFAC 2001) ethics framework. Drawing on six case studies of interactions involving significant accounting issues between audit engagement partners and finance directors in U.K.-listed companies, we analyze the threats and safeguards to auditor independence in fact that are relevant to the outcome of each interaction. Despite the U.K.'s comprehensive regulatory framework for independence, audit quality control, and independent inspection of firms, not all the interactions have a fully compliant outcome. Independence in fact is compromised where the safeguards in the framework are insufficient defense against the threats, particularly regarding intimidation and bullying during the audit process. Further examples of existing threats are identified and additional threats emerge, in particular an urgency threat, and a loss of face threat. Management motivation is found to be a key driver of pressure. Threats to independence arising within audit firms are not recognized in the current U.K. audit risk model. An extended risk model incorporating within-firm risk is suggested. This study demonstrates the need for continual improvement to regulatory frameworks; in particular it supports the recent U.S. Securities and Exchange Commission (SEC) rule on improper influence on the conduct of audits (Securities and Exchange Commission 2003a)

Primary Electric Propulsion Technology Study

An investigation of the 30-cm engineering-model-thruster technology with emphasis placed on the development of models for understanding and predicting the operational characteristics and wear-out mechanisms of the thruster as a function of operating or design parameters is presented. The task studies include: (1) the wear mechanisms and wear rates that determine the useful lifetime of the thruster discharge chamber; (2) cathode lifetime as determined by the depletion of barium from the barium-aluminate-impregnated-porous-tungsten insert that serves as a barium reservoir; (3) accelerator-grid-system technology; (4) a verification of the high-voltage propellant-flow-electrical-isolator design developed under NASA contract NAS3-20395 for operation at 10-kV applied voltage and 10-A equivalent propellant flow with mercury and argon propellants. A model was formulated for predicting performance

A grounded theory model of auditor-client negotiations

The central research question addressed in this paper is 'How do companies and their auditors resolve important audit issues?' In-depth interviews are conducted with the audit partners and finance directors of a varied group of six major UK listed companies who had recently experienced audit interactions involving 22 significant accounting issues. A grounded theory model is developed of the negotiation process and the factors that influence the nature of the outcome of interactions. This model identifies, as principal analytical categories, a range of general relationship factors and specific accounting issue factors that influence aspects of the negotiation process. These aspects include the parties involved, the strategies adopted, the quality of the financial reporting outcome and the ease with which it is achieved. A secondary outcome of the research is that distinct categories of audit engagement partner are identified, termed the crusader, the safe pair of hands, the accommodator and the truster