7,256 research outputs found
Owner challenges on major projects: The case of UK government
Many studies agree that owner organisations are important for successful project organising, but they tend to focus on particular aspects of project organising rather than providing a holistic analysis of owners as organisations. Our objective is to collect evidence of the full range of challenges public sector owners face in managing their major projects. After reviewing the literature on owner organisations, we carry out a case survey of 26 major projects to identify the principal challenges using a content analysis of UK National Audit Office Value for Money reports. Our original contribution is that the findings provide the first comprehensive picture of the full range of challenges of project organising faced by owner organisations. These findings push us theoretically to extend the scope of research in project organising to identify an extended core set of dynamic capabilities for project owner organisations to address these challenges
Physical optics analysis of a four-reflector antenna, part 1
Concern has been raised for the 64-m to 70-m antenna upgrade project that the 70-m system may experience greater S-band beam-pointing perturbations than the 64-m system. The S-band perturbations are due to minor (higher order) mode generation, causing subtle cross-polarization fields affecting beam pointing direction, as described herein. For the antennas in their present configuration (64 m), a slight S-band gain degradation of about 0.05 dB can be attributed to these effects. Therefore, a full physical optics analysis was performed for the present-day 64-m system, as described herein. The results were compared with past analyses and experimental observations in order to verify the algebra and computer code with the intent of deriving a valid analysis method for accurately analyzing the 70-m shaped dual reflector Cassegrainian antenna. The results of the new analysis appear to be in excellent agreement with previous analyses and experimental data
A new analysis of beam-waveguide antennas considering the presence of the enclosure
Beam-waveguide (BWG) antennas provide multiple frequency band operations and other operational benefits for large ground-station antennas. Present design practices use diffraction analyses that ignore the presence of the BWG enclosure and may be inaccurate at lower frequency bands for ground-station antennas operating over multiple frequency bands. Introduced here is a new analysis approach that considers the presence of the BWG enclosure. Results based on the new analysis have revealed new understandings of the performance degradation mechanisms in a BWG antenna and have provided direction for potential design improvements
Gain, phase and frequency stability of DSS-42 and DSS-43 vor Voyage Uranus encounter
Theoretically rigorous definitions are derived of such parameters as RF signal path length, phase delay, and phase/frequency stability in a Cassegrainian antenna applicable to a narrow bandwidth channel, as well as algorithms for evaluating these parameters. This work was performed in support of the Voyager spacecraft encounter with Uranus in January 1986. The information was needed to provide Voyager/Uranus radio science researchers with a rotational basis for deciding the best strategy to operate the three antennas involved during the crucial 5-hour occultation period of the encounter. Such recommendations are made at the end of the article
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Safety verification of ADA programs in MURPHY
MURPHY is a experimental methodology, which will include an integrated tool set, for building safety-critical, real-time software. Although it is language independent, many safety-critical software projects are currently planning to use Ada. This paper presents the semantic templates for the verification of the safety of Ada programs using Software Fault Tree Analysis. An example is shown of applying the technique to an Ada program, and the tools in the MURPHY tool set to aid in this type of analysis are described
Revisiting the project management knowledge framework: Rebalancing the framework to include transformation projects
Purpose
This paper highlights that extant project management (PM) bodies of knowledge have not fully addressed organisational transformation enabled by information systems projects. The purpose of this paper is to examine the transformation context in the PM disciplines. The authors argue that the execution-oriented PM bodies of knowledge are limited, as they place too much emphasis on the delivery outputs by the supplier rather than the achievement of beneficial outcomes by the project owner.
Design/methodology/approach
As a conceptual paper, this paper reviews extant PM bodies of knowledge, life cycle models, the context of organisational transformation and benefits realisation, and the distinction between a project owner’s and the project supplier’s capabilities.
Findings
A new PM knowledge framework is provided as an advanced research frame for future works by enhancing Peter Morris’ Management of Projects framework by employing the conceptual lens of Winch’s Three Domains of Project Organising model.
Originality/value
The advanced model emphasises the necessity of distinguishing a project owner’s and a supplier’s PM capability and knowledge to achieve successful IS-enabled organisational transformation. Through this effort to resolve the fragmentation and specialisation problems in PM disciplines, the model can be used as a theoretical groundwork for the advancement of PM research
Postpartum Visit Attendance Increases the Use of Modern Contraceptives
Background. Delays in postpartum contraceptive use may increase risk for unintended or rapid repeat pregnancies. The postpartum care visit (PPCV) is a good opportunity for women to discuss family planning options with their health care providers. This study examined the association between PPCV attendance and modern contraceptive use using data from a managed care organization. Methods. Claims and demographic and administrative data came from a nonprofit managed care organization in Virginia (2008–2012). Information on the most recent delivery for mothers with singleton births was analyzed (N = 24,619). Routine PPCV (yes, no) and modern contraceptive use were both dichotomized. Descriptive analyses provided percentages, frequencies, and means. Multiple logistic regression was conducted and ORs and 95% CIs were calculated. Results. More than half of the women did not attend their PPCV (50.8%) and 86.9% had no modern contraceptive use. After controlling for the effects of confounders, women with PPCV were 50% more likely to use modern contraceptive methods than women with no PPCV (OR = 1.50, 95% CI = 1.31, 1.72). Conclusions. These findings highlight the importance of PPCV in improving modern contraceptive use and guide health care policy in the effort of reducing unintended pregnancy rates
Third-order optical autocorrelator for time-domain operation at telecommunication wavelengths
We report on amorphous organic thin films that exhibit efficient third-harmonic generation at telecommunication wavelengths. At 1550 nm, micrometer-thick samples generate up to 17 µW of green light with input power of 250 mW delivered by an optical parametric oscillator. This high conversion efficiency is achieved without phase matching or cascading of quadratic nonlinear effects. With these films, we demonstrate a low-cost, sensitive third-order autocorrelator that can be used in the time-frequency domain
Hydrodynamic simulations with the Godunov SPH
We present results based on an implementation of the Godunov Smoothed
Particle Hydrodynamics (GSPH), originally developed by Inutsuka (2002), in the
GADGET-3 hydrodynamic code. We first review the derivation of the GSPH
discretization of the equations of moment and energy conservation, starting
from the convolution of these equations with the interpolating kernel. The two
most important aspects of the numerical implementation of these equations are
(a) the appearance of fluid velocity and pressure obtained from the solution of
the Riemann problem between each pair of particles, and (b the absence of an
artificial viscosity term. We carry out three different controlled
hydrodynamical three-dimensional tests, namely the Sod shock tube, the
development of Kelvin-Helmholtz instabilities in a shear flow test, and the
"blob" test describing the evolution of a cold cloud moving against a hot wind.
The results of our tests confirm and extend in a number of aspects those
recently obtained by Cha (2010): (i) GSPH provides a much improved description
of contact discontinuities, with respect to SPH, thus avoiding the appearance
of spurious pressure forces; (ii) GSPH is able to follow the development of
gas-dynamical instabilities, such as the Kevin--Helmholtz and the
Rayleigh-Taylor ones; (iii) as a result, GSPH describes the development of curl
structures in the shear-flow test and the dissolution of the cold cloud in the
"blob" test.
We also discuss in detail the effect on the performances of GSPH of changing
different aspects of its implementation. The results of our tests demonstrate
that GSPH is in fact a highly promising hydrodynamic scheme, also to be coupled
to an N-body solver, for astrophysical and cosmological applications.
[abridged]Comment: 19 pages, 13 figures, MNRAS accepted, high resolution version can be
obtained at
http://adlibitum.oats.inaf.it/borgani/html/papers/gsph_hydrosim.pd
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