Uncertainty quantification of microclimate variables in building energy models

The last decade has seen a surge in the need for uncertainty analysis (UA) for building energy assessment. The rigorous determination of uncertainty in model parameters is a vital but often overlooked part of UA. To undertake this, one has to turn one's attention to a thriving area in engineering statistics that focuses on uncertainty quantification (UQ) for short. This paper applies dedicated methods and theories that are emerging in this area of statistics to the field of building energy models, and specifically to the microclimate variables embedded in them. We argue that knowing the uncertainty in these variables is a vital prerequisite for ensuing UA of whole building behaviour. Indeed, significant discrepancies have been observed between the predicted and measured state variables of building microclimates. This paper uses a set of approaches from the growing UQ arsenal, mostly regression-based methods, to develop statistical models that quantify the uncertainties in the following most significant microclimate variables: local temperature, wind speed, wind pressure and solar irradiation. These are the microclimate variables used by building energy models to define boundary conditions that encapsulate the interaction of the building with the surrounding physical environment. Although our analysis is generically applicable to any of the current energy models, we will base our UQ examples on the energy model used in EnergyPlus.     

Evaluation of Hypolimnetic Oxygen Demand in a Large Eutrophic Raw Water Reservoir, San Vicente Reservoir, Calif.

Hypolimnetic oxygenation can improve water quality by decreasing hypolimnetic accumulation of reduced compounds that complicate potable water treatment. Historically, aeration systems have been undersized because designers have not accounted for increases in sediment oxygen demand (SOD) resulting from the operation of aeration systems. A comprehensive study was performed to estimate the hypolimnetic oxygen demand (HOD) in San Vicente Reservoir, a eutrophic raw water reservoir in San Diego. Chamber experiments confirmed that turbulence and oxygen concentration at the sediment-water interface dramatically affected SOD. Values ranged from under 0.2?g/m2/day under quiescent low-oxygen conditions to over 1.0?g/m2/day under turbulent high-oxygen conditions. Based on a statistical evaluation of historical oxygen concentrations in the reservoir and anticipated increases in SOD resulting from operation of an oxygenation system, a design HOD of 16,400?kg/day was estimated. This is approximately four times the HOD observed in the spring after the onset of thermal stratification. Laboratory chamber experiments confirmed that maintenance of a well-oxygenated sediment-water interface inhibited the release of phosphate, ammonia, iron, and manganese from sediments. In addition, hydrodynamic modeling using DYRESM-WQ showed that operation of a linear diffuser oxygenation system would not significantly affect thermal stratification.     

Test Case Generation for Mutation-based Testing of Timeliness

Temporal correctness is crucial for real-time systems. Few methods exist to test temporal correctness and most methods used in practice are ad-hoc. A problem with testing real-time applications is the response-time dependency on the execution order of concurrent tasks. Execution order in turn depends on execution environment properties such as scheduling protocols, use of mutual exclusive resources as well as the point in time when stimuli is injected. Model based mutation testing has previously been proposed to determine the execution orders that need to be verified to increase confidence in timeliness. An effective way to automatically generate such test cases for dynamic real-time systems is still needed. This paper presents a method using heuristic-driven simulation to generate test cases.     

Thermal design and analysis of a multi-stage 30 K radiative cooling system for EPIC

The Experimental Probe of Inflationary Cosmology (EPIC) is an implementation of the NASA Einstein Inflation Probe mission, to answer questions about the physics of Inflation in the early Universe by measuring the polarization of the Cosmic Microwave Background (CMB). The mission relies on a passive cooling system to cool the enclosure of a telescope to 30 K; a cryocooler then cools this enclosure to 18 K and the telescope to 4 K. Subsequently, an Adiabatic Demagnetization Refrigerator further cools a large Focal Plane to ∼100 mK. For this mission, the telescope has an aperture of 1.4 m, and the spacecraft’s symmetry axis is oriented ∼45° relative to the direction of the sun. The spacecraft will be spun at ∼0.5 rpm around this axis, which then precesses on the sky at 1 rph. The passive system must both supply the necessary cooling power for the cryocooler and meet demanding temperature stability requirements. We describe the thermal design of a passive cooling system consisting of four V-groove radiators for shielding of solar radiation and cooling the telescope to 30 K. The design realizes loads of 20 and 68 mW at the 4 K and 18 K stages on the cooler, respectively. A lower cost option for reaching 40 K with three V-groove radiators is also described. The analysis includes radiation coupling between stages of the radiators and sunshields, and parasitic conduction in the bipod support, harnesses, and ADR leads. Dynamic effects are also estimated, including the very small variations in temperature due to the scan motion of the spacecraft.     

Security services as coping mechanisms: an investigation into user intention to adopt an email authentication service

Email plays an important role in the digital economy but is threatened by increasingly sophisticated cybercrimes. A number of security services have been developed, including an email authentication service designed to cope with email threats. It remains unknown how users perceive and evaluate these security services and consequently form their adoption intention. Drawing on the Technology Acceptance Model and Technology Threat Avoidance Theory, this paper investigates the factors that affect user intention to adopt an email authentication service. Our results show that user intention to adopt an email security service is contingent upon users' perception of risk and evaluation of both internal and external coping strategies. This study contributes to research in security service adoption, service success and design, and information security behaviour.     

Structural Engineering with NiTi. I: Basic Materials Characterization

The overarching goal of this two-part paper is to provide a more unified understanding of NiTi shape memory alloys intended for use in structural engineering applications. Here, we present results from basic materials characterization of large diameter polycrystalline NiTi bars. Deformation processed bars with diameters of 12.7, 19.1, and 31.8?mm and various heat treatments were characterized at multiple length scales. Transmission electron microscopy revealed a nanometer scale precipitate structure present in the heat-treated, but not as-received bars. Spatial crystallographic texture measurements performed with electron backscatter diffraction, reveal a 〈111〉 texture along the longitudinal bar drawing axis in the majority of the bar, with a secondary longitudinal 〈110〉 component near the center of the bars. The prominence of the 〈110〉 texture increases with decreasing bar diameter or increasing percentage of deformation processing. Transformation temperatures and hardness were measured on samples extracted from the bars and are shown to depend strongly on bar heat treatment, but not bar diameter. The fine coherent precipitate structure induced during low temperature aging places transformation temperatures in the pseudoelastic range at room temperature and can be used to tailor material hardness.     

Chemical supply chain network optimization

Chemical supply chain networks provide large opportunities for cost reductions through the redesign of the flow of material from producer to customer. In this paper we present a mixed-integer linear program (MILP) capable of optimizing a multi-product supply chain network made up of production sites, an arbitrary number of echelons of distribution centers, and customer sites. The emphasis of our approach is on the redesign of existing supply chain networks. The model does not lump customer demand into zones, but rather deals with individual customer demand to directly address customer preferred mode of transport at each location. Historical records can be used to fix decision variables in the model so that a base case can be computed to validate the model and contrast it against the optimized network. The details inherent in this approach allow the optimization results to be partitioned and prioritized for implementation. The model results are processed to assign cost components to individual customer records. A simple case study is presented to illustrate the method and actual industrial results are reviewed.     

Public mental health: The role of population-based and macrosystems interventions in the wake of Hurricane Katrina.

Policy makers and decision makers are struggling to recognize the needs of shattered communities in the wake of unimaginable devastation. Professional psychology is providing some of the answers as it examines the consequences of disaster. The authors, 6 U.S. Public Health Service commissioned officers, describe their experiences in this new arena. Working at the federal, state, and local levels of government during the national response to the Hurricane Katrina disaster, the authors strive to identify high-value practice areas and define new roles for professional psychologists. The authors suggest that traditional crisis and trauma interventions are expanding to include nontraditional population-based and macrosystems-level interventions. Such roles are explored in narrative form, providing professional and personal insight into the impact that psychologists can have on decision makers who recognize their value and position them effectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved)