963 research outputs found
The 1980-90 shuttle star catalog for onboard and ground programs
The 1980-90 shuttle star catalog for onboard and ground programs is presented. The data used in this catalog are explained according to derivation, input, format for the catalog, and preparation. The tables include the computer program listing, input star position, and the computed star positions for the years 1980-90
The distribution of atomic hydrogen in the Jovian atmosphere
An analysis is presented of the Voyager and IUE lyman alpha spectra of the Jovian equatorial emission in which was derived a zonal asymmetry in the hydrogen column abundance. Using two estimates of the fraction of Lyman alpha which is due to direct excitation by charged particle precipitation from the ionosphere, upper and lower limits were derived to the H column abundance within and without the perturbed region. That the asymmetry in H abundance may be due to localized heating near the homopause with a consequent rise in scale height is shown. The derived exospheric temperature remains fairly constant with longitude. The required additional heat input over the bulge region, 0.02 erg/cm/s, is supplied by an additional flux of magnetospheric electrons due to Jupiter's magnetic anomaly
Potassium Rankine cycle vapor chamber (heat pipe) radiator study
A structurally integrated vapor chamber fin (heat pipe) radiator is defined and evaluated as a potential candidate for rejecting waste heat from the potassium Rankine cycle powerplant. Several vapor chamber fin geometries, using stainless steel construction, are evaluated and an optimum is selected. A comparison is made with an operationally equivalent conduction fin radiator. Both radiators employ NaK-78 in the primary coolant loop. In addition, the Vapor Chamber Fin (VCF) radiator utilizes sodium in the vapor chambers. Preliminary designs are developed for the conduction fin and VCF concepts. Performance tests on a single vapor chamber were conducted to verify the VCF design. A comparison shows the conduction fin radiator easier to fabricate, but heavier in weight, particularly as meteoroid protection requirements become more stringent. While the analysis was performed assuming the potassium Rankine cycle powerplant, the results are equally applicable to any system radiating heat to space in the 900 to 1400 F temperature range
Dynamic Capabilities: Innovation Project Portfolio Management
Innovation Project Portfolio Management (IPPM) practices are a dynamic capability that provides competitive advantage by dynamically adjusting the organisation’s portfolio of projects and resource allocation profile for the best innovation outcomes. A relatively new body of empirical research into IPPM practices is starting to generate findings related to IPPM practices and innovation outcomes. However this research is fragmented and lacks a unifying theoretical base. The resource-based view of strategy, in particular the dynamic capabilities approach, provides a theoretical framework to unify IPPM research. A ‘processes, positions and paths’ perspective on IPPM practices helps to clarify the ways that IPPM practices contribute to competitive advantage. Existing empirical research into the processes used for IPPM reveals some links to innovation outcomes, but does not try to explain causality. Improved understanding of the mechanisms responsible for competitive advantage through IPPM practices is found in research on positions (how IPPM processes draw upon and contribute to the underlying resource position) and paths (the role of past decisions and organisational paths in shaping IPPM processes as well as future options and decisions).14 page(s
Eyes Wide Shut: Expanding the view of portfolio management
This conceptual paper examines our existing world-view portfolio is defined the management of that portfolios from that of project and new product development portfolios to other portfolios that exist in an organisation, such as the asset portfolio, resource portfolio and ideas portfolio. Portfolios do not exist in isolation in an organisational context, but instead overlap and interact. This paper argues that there is a need to move another step higher, and examine the relationships between portfolios of projects and related activities across an organisation in order to optimise outcomes across the organisation. We propose the need for `enterprise portfolio management and suggest that this approach has the potential to improve organisational efficiency, and in the longer term could be a source of competitive advantage
Project portfolio management for product innovation
The purpose of this paper is to create a benchmark and identify best practices for Project Portfolio Management (PPM) for both tangible product-based and service product-based development project portfolios. A questionnaire was developed to gather data to compare the PPM methods used, PPM performance, PPM challenges, and resulting new product success measures in 60 Australian organisations in a diverse range of service and manufacturing industries. The paper finds that PPM practices are shown to be very similar for service product development project portfolios and tangible product development project portfolios. New product success rates show strong correlation with measures of PPM performance and the use of some PPM methods is correlated with specific PPM performance outcomes. The findings in this paper are based on a survey of a diverse sample of 60 Australian organisations. The results are strengthened by comparisons with similar North American research; however, they may not be representative of all environments. Research in other regions would further qualify the findings. As each organisation's PPM process is unique, case study methods are recommended for future studies to capture more of the complexity in the environment. The paper shows that PPM practitioners and executives who make decisions about the development of tangible products and/or service products will benefit from the findings. This paper extends the existing understanding of PPM practices to include service development project portfolios as well as tangible product development project portfolios and strengthens the links between PPM practices and outcomes
Learning investments and organizational capabilities: case studies on the development of project portfolio management capabilities
Purpose The purpose of this paper is to improve understanding and provide guidance for investments in organizational learning mechanisms for the establishment and evolution of organizational capabilities such as project portfolio management (PPM) and project management capabilities. Design/methodology/approach A multiple-case study research project investigates the development of PPM capabilities in six successful organizations across diverse industries. Findings The research indicates that PPM and organizational learning are dynamic capabilities that enhance an organization's ability to achieve and maintain competitive advantage in dynamic environments. PPM capabilities are shown to co-evolve through a combination of tacit experience accumulation, explicit knowledge articulation and explicit knowledge codification learning mechanisms. Although all three learning mechanisms are important throughout the establishment and evolution of PPM capability development, the research indicates that the development of an effective PPM capability will require particularly strong investments in enhancing tacit experience accumulation mechanisms and explicit knowledge codification mechanisms during the initial establishment or during periods of radical change to the PPM process
Long life reliability thermal control systems study
The results of a program undertaken to conceptually design and evaluate a passive, high reliability, long life thermal control system for space station application are presented. The program consisted of four steps: (1) investigate and select potential thermal system elements; (2) conceive, evaluate and select a thermal control system using these elements; (3) conduct a verification test of a prototype segment of the selected system; and (4) evaluate the utilization of waste heat from the power supply. The result of this project is a conceptual thermal control system design which employs heat pipes as primary components, both for heat transport and temperature control. The system, its evaluation, and the test results are described
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