5,750 research outputs found
Recommended from our members
The Guiding of Learning: An Overview, Analysis and Classification of Guides
Of Incentive, Bias, and Behaviour: An Empirical Economic Investigation into Project Delivery Constructs Influencing the Adoption of Building Information Modelling
Building Information Modelling (BIM) is a collaborative construction platform allowing for digital databases, real-time change management, and a high degree of information reuse catalysing increased quality of work, enhanced productivity, and lower costs. Yet, overall adoption rates within industry remain vexingly low. Integrated Project Delivery (IPD) is currently the only contractual incentive vehicle available for BIM, and indeed the full potential of both are only realised when employed together; even so, uptake rates of IPD exist even lower. In response, this research evaluates hitherto ill-explored factors influencing the adoption of BIM by empirically testing hypotheses related to the impacts of three compounding theories upon the BIM decision calculus. Specifically, the incentive theory, the theory of acceptance and use of technology (UTAUT), and the status quo bias model. The research approaches BIM adoption holistically at the organizational, individual, transactional, and behavioural levels through a mixed design combining five quantitative, cross-sectional, questionnaire-based studies and one interview-based pre-test/post-test case study with sample populations including a Fortune 100 contractor, internationally renowned trade groups, and arguably the most progressive municipal construction client in the world. Data was collected using purposive sampling and analysed quantitatively through Structural Equation Modelling (SEM) and qualitatively with Directed Content Analysis (DCA). Primary conclusions are that BIM decisions are hierarchical; BIM adoption involves a general higher-level decision-making requiring stakeholders’ consensus; BIM utilization involves a specific lower-level decision-making with managerial discretion; economic incentives and competitive pressure influence higher-level decisions; non-economic factors influence lower-level decisions but are moderated by organizations’ type and size; organizations’ size and the degree of managerial discretion are inversely related; strength of the effects vary across and within the three theory-based factors that influence BIM adoption; and the effects of leadership and organizational culture remain unaccounted for and require investigation
Three Super-Earths Orbiting HD 7924
We report the discovery of two super-Earth mass planets orbiting the nearby
K0.5 dwarf HD 7924 which was previously known to host one small planet. The new
companions have masses of 7.9 and 6.4 M, and orbital periods of 15.3
and 24.5 days. We perform a joint analysis of high-precision radial velocity
data from Keck/HIRES and the new Automated Planet Finder Telescope (APF) to
robustly detect three total planets in the system. We refine the ephemeris of
the previously known planet using five years of new Keck data and high-cadence
observations over the last 1.3 years with the APF. With this new ephemeris, we
show that a previous transit search for the inner-most planet would have
covered 70% of the predicted ingress or egress times. Photometric data
collected over the last eight years using the Automated Photometric Telescope
shows no evidence for transits of any of the planets, which would be detectable
if the planets transit and their compositions are hydrogen-dominated. We detect
a long-period signal that we interpret as the stellar magnetic activity cycle
since it is strongly correlated with the Ca II H and K activity index. We also
detect two additional short-period signals that we attribute to
rotationally-modulated starspots and a one month alias. The high-cadence APF
data help to distinguish between the true orbital periods and aliases caused by
the window function of the Keck data. The planets orbiting HD 7924 are a local
example of the compact, multi-planet systems that the Kepler Mission found in
great abundance.Comment: Accepted to ApJ on 4/7/201
Corrosion resistance of stainless steels during thermal cycling in alkali nitrate molten salts.
The corrosion behavior of three austenitic stainless steels was evaluated during thermal cycling in molten salt mixtures consisting of NaNO{sub 3} and KNO{sub 3}. Corrosion tests were conducted with Types 316, 316L and 304 stainless steels for more than 4000 hours and 500 thermal cycles at a maximum temperature of 565 C. Corrosion rates were determined by chemically descaling coupons. Metal losses ranged from 5 to 16 microns and thermal cycling resulted in moderately higher corrosion rates compared to isothermal conditions. Type 316 SS was somewhat more corrosion resistant than Type 304 SS in these tests. The effect of carbon content on corrosion resistance was small, as 316L SS corroded only slightly slower than 316 SS. The corrosion rates increased as the dissolved chloride content of the molten salt mixtures increased. Chloride concentrations approximating 1 wt.%, coupled with thermal cycling, resulted in linear weight loss kinetics, rather than parabolic kinetics, which described corrosion rates for all other conditions. Optical microscopy and electron microprobe analysis revealed that the corrosion products consisted of iron-chromium spinel, magnetite, and sodium ferrite, organized as separate layers. Microanalysis of the elemental composition of the corrosion products further demonstrated that the chromium content of the iron-chromium spinel layer was relatively high for conditions in which parabolic kinetics were observed. However, linear kinetics were observed when the spinel layer contained relatively little chromium
THE FUTURE OF FEDERAL PROGRAMS FOR SOUTHERN COMMODITIES
Political Economy,
Cavitation Noise from Underwater Projectiles
This report describes measurements of high frequency noise produced by projectiles cavitating in a high velocity stream of water. Spherical and ellipsoidal focusing reflectors were used in conjunction with a Brush CC-11A hydrophone to locate the noise source
Utah Water Quality- Utah Ground Water
Ground water is important to the economic and physical well-being of the people of Utah. About 95% of Utah\u27s fresh water is ground water. It provides more than 70% of the state\u27s drinking water and is a major source of water for agriculture and irrigation
- …