26 research outputs found
Technique of uncertainty and sensitivity analysis for sustainable building energy systems performance calculations
Sustainable buildings design process is typical for modeling and simulation usage. The main reason is because there is generally no experience with such buildings and there is lot of new approaches and technical solutions to be used. Computer simulation could be supporting tool in engineering design process and can bring the good way for reducing energy consumption together with optimalization algorithm. For the optimization process we have to know which most sensitive input parametr from many of them has to be investigate. Therefore at first is necessary to perform the sensitivity analysis and find out the "strongest" input parametrs which most affecting the results under observation. Also still the simulation tools are mainly using to predict energy consumption, boiler and chiller loads, indoor air quality, etc. before the building is build. The information about the building envelope, schedule and HVAC components are unclear and can bring large uncertainty in results by setting this inputs to the simulation tools. Paper presents preview of uncertainty and sensitivity analysis. This techniques are shown on case study concretely BESTEST case600 with DRYCOLD climate conditions. Also systems VAV (variable volume of air) and water fancoil system are compared. For this prototype the simulation tool IES was chosen
Stochastic Micro-Modelling of Historic Masonry
The non-linear analysis of historic masonry structures can be difficult to perform due to the highly irregular geometric features, the inherent variability within the materials, as well as the limited amount of experimental data available. The present work details a specific methodology and result for the analysis of the compressive strength of the masonry found in walls of St. Annâs Church in the Czech Republic. A multi-scale 2D finite element modelling approach was adopted. In a mesoscale-level representation of masonry, âsmall stonesâ were grouped in with the mortar and treated as a matrix component with homogenized properties, while large stones were treated as discrete inhomogeneities. To characterize this matrix component, microscale-level models were used, in which only the âsmall stonesâ and mortar were represented. By simulating uniaxial compression and tension tests on multiple microscalelevel models, statistical distributions for compressive and tensile strength, stiffness, and fracture energy were determined. On the mesoscale-level, overall stiffness and compressive strength were determined by simulating uniaxial compression tests on models involving only the large stones embedded in the homogenized matrix. The matrix was considered either as spatially uniform or variable. In the latter case, it was modeled with random fields based on
the propertiesâ distributions obtained from the micro-scale model analyses. Furthermore, the multi-scale study was performed for two different threshold sizes defining the âsmall stonesâ to compare differences. Approximate qualitative methods were utilized to validate the results. Overall, decreasing compressive strength was observed from the plain mortar to the microscale model of mortar with âsmall stonesâ to the meso-scale model of masonry. Models where matrix variability was represented with random fields exhibited similar failure mechanisms but with strengths 5-6% lower than models with a uniform matrix. Therefore, the effect of the spatial variability of the matrix properties was deemed insignificant
Hybrid fiber reinforcement and crack formation in cementitious composite materials
The use of different types of fibers simultaneously for reinforcing cementitious
matrices is motivated by the concept of a multi-scale nature of the
crack propagation process. Fibers with different geometrical and mechanical properties
are used to bridge cracks of different sizes from the micro- to the macroscale.
In this study, the performance of different fiber reinforced cementitious
composites is assessed in terms of their tensile stress-crack opening behavior. The
results obtained from this investigation allow a direct quantitative comparison of
the behavior obtained from the different fiber reinforcement systems. The research
described in this paper shows that the multi-scale conception of cracking and the
use of hybrid fiber reinforcements do not necessarily result in an improved tensile
behavior of the composite. Particular material design requirements may nevertheless
justify the use of hybrid fiber reinforcements.Fundação para a CiĂȘncia e a Tecnologia (FCT) - SFRH / BD / 36515 / 200
Liberal intervention in the foreign policy thinking of Tony Blair and David Cameron
David Cameron was a critic of Tony Blairâs doctrine of the international community, which was used to justify war in Kosovo and more controversially in Iraq, suggesting caution in projecting military force abroad while in opposition. However, and in spite of making severe cuts to the defence budget, the Cameron-led Coalition government signed Britain up to a military intervention in Libya within a year of coming into office. What does this say about the place liberal interventionism occupies in contemporary British foreign policy? To answer this question, this article studies the nature of what we describe as the âbounded liberalâ tradition that has informed British foreign policy thinking since 1945, suggesting that it puts a distinctly UK national twist on conventional conservative thought about international affairs. Its components are: scepticism of grand schemes to remake the world; instinctive Atlanticism; security through collective endeavour; and anti-appeasement. We then compare and contrast the conditions for intervention set out by Tony Blair and David Cameron. We explain the similarities but crucially also the vital differences between the two leadersâ thinking on intervention, with particular reference to Cameronâs perception that Downing Street needed to loosen its control over foreign policy-making after Iraq. Our argument is that policy substance, policy style and party political dilemmas prompted Blair and Cameron to reconnect British foreign policy with its ethical roots, ingraining a bounded liberal posture to British foreign policy after the moral bankruptcy of the John Major years. This return to a patient, pragmatic and ethically informed foreign policy meant that military operations in Kosovo and Libya were undertaken in quite different circumstances, yet came to be justified by similar arguments from the two leaders
Critically evaluating collaborative research: why is it difficult to extend truth tests to reality tests?
We argue that critical evaluation achieves the reflexivity needed to facilitate collaboration by proposing boundary-negotiating artefacts to configure a joint action domain. Those objects become mediators for innovation by triggering controversies, conceived preventatively via an organized extension of what Boltanski calls âtruth testsâ to âreality testsâ so that they dynamize ongoing affairs. However, critical evaluation must also anticipate actorsâ reappropriation of boundary-negotiating artefacts in the effort to protect their rights, stakes or room for manoeuvre. Three scenarios commonly arise: avoidance or utopian projecting, enactment of inverted reality tests, and disavowal through role exchange. The article develops these propositions through the reconstruction of a modified theory-based evaluation of a collaborative research programme. The programme set out to explore how evidence from health research could be used rapidly and effectively in the context of practical problems and organizational challenges, so an internal evaluation was set up to facilitate learning during the process. What ensued, however, was a loss of trust between partners, resolved only by repositioning the evaluation as a reflective academic study, reducing its reflexive capacity to intervene on the level of activity and organizational integration. We conclude that doing successful critical evaluation and, more generally, achieving political pertinence for social scientific discourses depends on creating the conditions in which actors are able to take the risks and share the costs associated with the enhanced level of reflexivity necessary to engage in collective action as well as knowledge production
Impact of office buildings environmental systems control strategy on indoor environment quality and energy use in different climatic regions
10th International Conference on Healthy Buildings 201232238-224
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Descriptions of reference LWR facilities for analysis of nuclear fuel cycles
To contribute to the Department of Energy's identification of needs for improved environmental controls in nuclear fuel cycles, a study was made of a light water reactor system. A reference LWR fuel cycle was defined, and each step in this cycle was characterized by facility description and mainline and effluent treatment process performance. The reference fuel cycle uses fresh uranium in light water reactors. Final treatment and ultimate disposition of waste from the fuel cycle steps were not included, and the waste is assumed to be disposed of by approved but currently undefined means. The characterization of the reference fuel cycle system is intended as basic information for further evaluation of alternative effluent control systems
Technique of uncertainty and sensitivity analysis for sustainable building energy systems performance calculations
Sustainable buildings design process is typical for modeling and simulation usage. The main reason is because there is generally no experience with such buildings and there is lot of new approaches and technical solutions to be used. Computer simulation could be supporting tool in engineering design process and can bring the good way for reducing energy consumption together with optimalization algorithm. For the optimization process we have to know which most sensitive input parametr from many of them has to be investigate. Therefore at first is necessary to perform the sensitivity analysis and find out the "strongest" input parametrs which most affecting the results under observation. Also still the simulation tools are mainly using to predict energy consumption, boiler and chiller loads, indoor air quality, etc. before the building is build. The information about the building envelope, schedule and HVAC components are unclear and can bring large uncertainty in results by setting this inputs to the simulation tools. Paper presents preview of uncertainty and sensitivity analysis. This techniques are shown on case study concretely BESTEST case600 with DRYCOLD climate conditions. Also systems VAV (variable volume of air) and water fancoil system are compared. For this prototype the simulation tool IES was chosen