10,006 research outputs found
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Comparing software design methodologies through process modeling
Recently, the importance of consolidating existing software engineering approaches and concepts has been well recognized by the software engineering community [Boa90]. We believe that study of Software Design Methodologies (SDMs) is an excellent place to start. To achieve this, we must be able to objectively and systematically compare SDMs.Quite a number of SDMs have been developed and compared over the past two decades. An accurate comparison aids in codifying, enhancing and integrating SDMs. However, after analyzing the existing comparisons, we found that these comparisons are often based largely upon the experiences of the practitioners and the intuitive understandings of the authors. Consequently, these comparisons are subjective and affected by application domains. We also analyzed a number of comparisons which use quasinormal approaches to comparing SDMs. We found that these comparisons are often based on hypothesizing features required by the design process and software design problems. In order to compare SDMs more scientifically, in this thesis we introduce a systematic approach (called CDM (Comparing Design Methodologies)) to objectively comparing SDMs. We hope that using CDM will lead to precise, explicit and complete comparisons.CDM is based on modeling SDMs and classifying their components (e.g. guidelines and notations). Modeling SDMs entails decomposing them into components. The classification of the components illustrates which components address similar design issues and/or have similar structures. Similar components then may be further modeled to aid in understanding more precisely their similarities and differences. The models of the SDMs are also used as the bases for conjectures and conclusions about the differences between the SDMs.Two key components required by CDM are 1) a fair Base Framework (BF) to classify parts of SDMs and a comprehensive Modeling Formalism (MF) to model all these parts. In this thesis we address these two problems by suggesting an evolutionary strategy for developing such a BF and MF. Then we present the BF and MF we have developed using this strategy, and demonstrate how they have been and can be used. Further we evaluate the BF and MF based on their applications and suggest how they might be enhanced. In doing this, we intend to illustrate that increasingly fair BFs and MFs can be developed by using this development strategy.We believe that this sort of iterative evolutionary development of key framework and modeling formalisms is consistent with the ways in which more mature scientific disciplines operate. Thus, we hope that this effort indicates a way in which software engineering can begin to grow into a mature scientific discipline. Further, we suggest that this evolutionary development of BFs and MFs should be a community-wide activity.In this thesis we demonstrate this approach by using it to compare six SDMs (JSD [Jac83], Booch's Object Oriented Design (BOOD) [Boo86], RDM [PC86], SD [YC79, SMC74], LCP [War76], and DSSD [Orr77]). We compared our SDM comparisons against other comparisons obtained using other approaches. The results of this comparison demonstrate that process modeling [Ost87, KH88] is valuable as a powerful tool in analysis of software development approaches. Besides, the SDM comparisons result, we obtained through this effort are by themselves valuable for understanding software design activities and SDMs
Improved Ways to Compare Simulations to Data
Theoretical models for structure formation with Gaussian initial fluctuations
have been worked out in considerable detail and compared with observations on
various scales. It is on nonlinear scales \lsim 10 \ h^{-1}\ {\rm Mpc} that
the greatest differences exist between models that have been
normalized to agree on the largest scales with the COBE data; here especially
there is a need for better statistical tests which are simultaneously {\it
robust}, {\it discriminatory}, and {\it interpretable}. The era at which galaxy
and cluster formation occurs is also a critical test of some models. Needs for
the future include faster and cleverer codes, better control of cosmic variance
in simulations, better understanding of processes leading to galaxy formation,
better ways of comparing observational data with models, and better access to
observational and simulation data.Comment: 9 pages, self-extracting uuencoded postscript, encoded with uufile
Citywide Transportation Greenhouse Gas Emissions Inventories: A Review of Selected Methodologies
Outlines the methodological issues in creating transportation emissions inventories and how they affect the results, reviews currently used methodologies, and explores ways to integrate inventories with climate policies to inform reduction strategies
The Relationship of the Clinical Disc Margin and Bruch's Membrane Opening in Normal and Glaucoma Subjects.
PurposeWe tested the hypotheses that the mismatch between the clinical disc margin (CDM) and Bruch's membrane opening (BMO) is a function of BMO area (BMOA) and is affected by the presence of glaucoma.MethodsA total of 45 normal eyes (45 subjects) and 53 glaucomatous eyes (53 patients) were enrolled and underwent radial optic nerve head (ONH) imaging with spectral domain optical coherence tomography. The inner tip of the Bruch's membrane (BM) and the clinical disc margin were marked on radial scans and optic disc photographs, and were coregistered with custom software. The main outcome measure was the difference between the clinical disc area (CDA) and BMOA, or CDA-BMOA mismatch, as a function of BMOA and diagnosis. Multivariate regression analyses were used to explore the influence of glaucoma and BMOA on the mismatch.ResultsGlobal CDA was larger than BMOA in both groups but the difference was statistically significant only in the normal group (1.98 ± 0.37 vs. 1.85 ± 0.45 mm2, P = 0.02 in the normal group; 1.96 ± 0.38 vs. 1.89 ± 0.56 mm2, P = 0.08 in the glaucoma group). The sectoral CDA-BMOA mismatch was smaller in superotemporal (P = 0.04) and superonasal (P = 0.05) sectors in the glaucoma group. The normalized CDA-BMOA difference decreased with increasing BMOA in both groups (P < 0.001). Presence or severity of glaucoma did not affect the CDA-BMOA difference (P > 0.14).ConclusionsClinical disc area was larger than BMOA in normal and glaucoma eyes but reached statistical significance only in the former group. The CDA-BMOA mismatch diminished with increasing BMOA but was not affected by presence of glaucoma. These findings have important clinical implications regarding clinical evaluation of the ONH
Massive Milky Way Satellites in Cold and Warm Dark Matter: Dependence on Cosmology
We investigate the claim that the largest subhaloes in high resolution
dissipationless cold dark matter (CDM) simulations of the Milky Way are
dynamically inconsistent with observations of its most luminous satellites. We
find that the inconsistency is largely attributable to the large values of
\sigma_8 and n_s adopted in the discrepant simulations producing satellites
that form too early and therefore are too dense. We find the tension between
observations and simulations adopting parameters consistent with WMAP9 is
greatly diminished making the satellites a sensitive test of CDM. We find the
Via Lactea II halo to be atypical for haloes in a WMAP3 cosmology, a
discrepancy that we attribute to its earlier formation epoch than the mean for
its mass. We also explore warm dark matter (WDM) cosmologies for 1--4 keV
thermal relics. In 1 keV cosmologies subhaloes have circular velocities at kpc
scales ~ 60% lower than their CDM counterparts, but are reduced by only 10% in
4 keV cosmologies. Since relic masses < 2-3 keV are ruled out by constraints
from the number of Milky Way satellites and Lyman-\alpha\ forest, WDM has a
minor effect in reducing the densities of massive satellites. Given the
uncertainties on the mass and formation epoch of the Milky Way, the need for
reducing the satellite densities with baryonic effects or WDM is alleviated.Comment: 11 pages, 7 figures, submitted to MNRA
Sustainability Standards and Stakeholder Engagement: Lessons From Carbon Markets
Stakeholders play an increasingly active role in private governance, including development of standards for measuring sustainability. Building on prior studies focused on standards and stakeholder engagement, we use an innovation management theoretical lens to compare stakeholder engagement and standards developed in two carbon markets: the Climate Action Reserve and the U.N.’s Clean Development Mechanism. We develop and test hypotheses regarding how different processes of stakeholder engagement in standard development affect the number, identity, and age of stakeholders involved, as well as the variation and quality of the resulting standards. In doing so, we contribute to the growing literature on stakeholder engagement in developing sustainability standards
The X-Ray Concentration-Virial Mass Relation
We present the concentration (c)-virial mass (M) relation of 39 galaxy
systems ranging in mass from individual early-type galaxies up to the most
massive galaxy clusters, (0.06-20) x 10^{14} M_sun. We selected for analysis
the most relaxed systems possessing the highest quality data currently
available in the Chandra and XMM public data archives. A power-law model fitted
to the X-ray c-M relation requires at high significance (6.6 sigma) that c
decreases with increasing M, which is a general feature of CDM models. The
median and scatter of the c-M relation produced by the flat, concordance LCDM
model (Omega_m=0.3, sigma_8=0.9) agrees with the X-ray data provided the sample
is comprised of the most relaxed, early forming systems, which is consistent
with our selection criteria. Holding the rest of the cosmological parameters
fixed to those in the concordance model the c-M relation requires 0.76< sigma_8
<1.07 (99% conf.), assuming a 10% upward bias in the concentrations for early
forming systems. The tilted, low-sigma_8 model suggested by a new WMAP analysis
is rejected at 99.99% confidence, but a model with the same tilt and
normalization can be reconciled with the X-ray data by increasing the dark
energy equation of state parameter to w ~ -0.8. When imposing the additional
constraint of the tight relation between sigma_8 and Omega_m from studies of
cluster abundances, the X-ray c-M relation excludes (>99% conf.) both open CDM
models and flat CDM models with Omega_m ~1. This result provides novel evidence
for a flat, low-Omega_m universe with dark energy using observations only in
the local (z << 1) universe. Possible systematic errors in the X-ray mass
measurements of a magnitude ~10% suggested by CDM simulations do not change our
conclusions.Comment: Accepted for Publication in ApJ; 13 pages, 4 figures; minor
clarifications and updates; correlation coefficients corrected in Table 1
(correct values were used in the analysis in previous versions); conclusions
unchange
Recommended from our members
Construction safety and digital design: a review
As digital technologies become widely used in designing buildings and infrastructure, questions arise about
their impacts on construction safety. This review explores relationships between construction safety and
digital design practices with the aim of fostering and directing further research. It surveys state-of-the-art
research on databases, virtual reality, geographic information systems, 4D CAD, building information
modeling and sensing technologies, finding various digital tools for addressing safety issues in the
construction phase, but few tools to support design for construction safety. It also considers a literature on
safety critical, digital and design practices that raises a general concern about ‘mindlessness’ in the use of
technologies, and has implications for the emerging research agenda around construction safety and digital
design. Bringing these strands of literature together suggests new kinds of interventions, such as the
development of tools and processes for using digital models to promote mindfulness through multi-party
collaboration on safet
Constraints on decaying Dark Matter from XMM-Newton observations of M31
We derive constraints on parameters of the radiatively decaying Dark Matter
(DM) particles, using XMM-Newton EPIC spectra of the Andromeda galaxy (M31).
Using the observations of the outer (5'-13') parts of M31 we improve the
existing constraints. For the case of sterile neutrino DM, combining our
constraints with the latest computation of abundances of sterile neutrino in
the Dodelson-Widrow (DW) scenario, we obtain the lower mass limit m_s < 4 keV,
which is stronger than the previous one m_s < 6 kev, obtained recently by Asaka
et al. (2007) [hep-ph/0612182]. Comparing this limit with the most recent
results on Lyman-alpha forest analysis of Viel et al. (2007) [arXiv:0709.0131]
(m_s > 5.6 kev), we argue that the scenario in which all the DM is produced via
DW mechanism is ruled out. We discuss however other production mechanisms and
note that the sterile neutrino remains a viable candidate of Dark Matter,
either warm or cold.Comment: 13 pages, 12 figure
ORTHOGONALITY OF STRUCTURED DERIVED ENTITIES
Structured entities, derivative entities and their order are presented. The orthogonality metric for structured and derivative entities is build. This metric is implemented. The sets of structured entities and first order derivative entities will be evaluated and analyzed.structured entities, derivative entities, metric, sets.
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