295 research outputs found
Emerging Technologies In Building Energy Efficiency
The U.S. building stock are under continuous aging and deterioration with deferred maintenance that hinders their operation. Existing buildings account for more than 86% of the annual construction cost in the U.S. and often suffer from lack of acceptable level of thermal comfort, indoor air quality (IAQ) as well as high energy use and costs. Considering future energy constraints (e.g. global warming and energy resources) and cost (e.g. capital cost and operational cost) suggest a need for a paradigm shift in our current understanding of energy efficiency and indoor environmental quality (IEQ) of the older existing building stock. Major technological advances beyond our current knowledge are much needed to design energy efficient buildings and retrofit large numbers of buildings at scale. Our technologies advances should be converged on high performance building enclosure materials, advanced building controls, intelligent building mechanical systems, efficient building lighting fixtures, and smart building plug-load management. For example, currently, majority of the residential buildings and a significant number of commercial buildings in the U.S. do not have any building automation systems, suggesting an emerging need to develop low-cost building automation systems specifically for residential buildings. This presentation covers a wide range of much needed technological advances on different building components and systems in order to design energy efficient buildings or retrofit large numbers of buildings. The aim of this presentation is not only to provide opportunities to reduce energy consumption in older existing buildings but also to shed light on new solutions to harvest energy through buildings
Numerical Evaluation of the Local Weather Data Impacts on Cooling Energy Use of Buildings in an Urban Area
AbstractAccurate weather data plays an important role in the evaluation of building energy consumption in urban areas. The local air temperature and local wind speed can vary significantly due to the influence of microclimate conditions, while those parameters have a significant effect on energy demand especially in the summer. This study provides a new coupled numerical approach that building energy simulation (BES), using the airport weather data, transfers building surface temperature data to computational fluid dynamics (CFD) as the boundary conditions. In addition, the outdoor thermal environment is simulated using the CFD method and local weather data is calibrated and transferred to BES as the real-time meteorological data. A daily coupled simulation is performed for a building located in a specified urban density accounting for actual wind speed and direction. The comparison shows that the difference for daily building energy consumption is up to 2.5% using the airport weather data and local weather data. Therefore, accurate estimation of local weather data is necessary when on-site measured data is not available
Interplay of confinement and density on the heat transfer characteristics of nanoscale-confined gas
The effect of changing the Knudsen number on the thermal properties of static
argon gas within nanoscale confinement is investigated by three-dimensional
molecular dynamics simulations. Utilizing thermalized channel walls, it is
observed that regardless of the channel height and the gas density, the wall
force field affects the density and temperature distributions within
approximately 1 nm from each channel wall. As the gas density is increased for
constant channel height, the relative effect of the wall force field on the
motion of argon gas atoms and, consequently, the maximum normalized gas density
near the walls is decreased. Therefore, for the same Knudsen number, the
temperature jump for this case is higher than what is observed for the case in
which the channel height changes at a constant gas density. The normalized
effective thermal conductivity of the argon gas based on the heat flux that is
obtained by implementation of the Irving-Kirkwood method reveals that the two
cases give the same normalized effective thermal conductivity. For the constant
density case, the total thermal resistance increases as the Knudsen number
decreases while for the constant height case, it reduces considerably.
Meanwhile, it is observed that regardless of the method used to change the
Knudsen number, a considerable portion of the total thermal resistance refers
to interfacial and wall force field thermal resistance even for near micrometer
sized channels.Comment: 18 pages, 11 figure
Relapse coping strategies in young adults addicts: A quantitative study in Iran
Background: Cognitive-behavioral coping approach is known as an effective strategy to preventing relapse. Its goal is to forget incompatible behaviors and replaces them with the compatible answers. Objectives: This study examines relapse coping strategies in young adults in selected substance abuse treatment centers in Iran. Patients and Methods: The present is a descriptive cross-sectional study. The sample consisted of 70 self-referred young addicts (18-24 years). Adolescence Relapse Coping Questionnaire was used to assess relapse coping strategies. Descriptive statistics was used to analyze the data. Results: The findings revealed that 71.2 have experienced a relapse totally. It was hard to control the hypothetical high risk situation and they greatly wanted to use the substance (mean 7.39 of 10). Addicts have used of all three coping skills in »definitely would do» level. Conclusion: Enhancing self-efficacy through training coping skills, especially abstinence - focused coping skills to react properly in high risk situation can be useful. © 2016 Indian Psychiatric Society | Published by Wolters Kluwer - Medknow
Experimental Evaluations of the Impact of an Additive Oxidizing Electronic Air Cleaner on Particles and Gases
Electronic air cleaning (EAC) technologies have garnered significant attention for use in buildings. Many EAC technologies rely on the addition of reactive constituents to indoor air to react with gas-phase compounds, enhance particle deposition, and/or inactivate microorganisms. However, limited data are available on the efficacy of many EAC technologies and their potential to form chemical byproducts during operation. Here we experimentally evaluate the indoor air quality impacts, specifically targeting particles and gases but not microbial constituents, of a commercially available additive oxidizing EAC that generates positive and negative ions and hydrogen peroxide (H2O2). Tests were conducted in a large unoccupied test chamber in Chicago, IL and an unoccupied laboratory in Portland, OR under a combination of natural conditions (i.e., without pollutant injection) and perturbation conditions (i.e., with pollutant injection and decay). A combination of integrated and time-resolved measurements was used across both test locations. Chamber tests at lower airflow rates demonstrated that operation of the EAC: (i) had no discernible impact on particle concentrations or particle loss rates, with estimated clean air delivery rates (CADRs) for various particle measures less than ±10 m3/h, (ii) was associated with apparent decreases in some volatile organic compounds (VOCs) and increases in other VOCs and aldehydes, especially acetaldehyde, although a combination of high propagated uncertainty, limitations in test methods (e.g., lack of replicates), and variability between repeated tests limit what quantitative conclusions can be drawn regarding gas-phase organics; (iii) did generate H2O2, assessed using a crude measure, and (iv) did not generate ozone (O3). Laboratory tests at higher airflow rates, which involved injection and decay of particles and a single VOC (limonene), both simultaneously and separately, demonstrated that: (i) pollutant loss rates for both particles and limonene were slightly lower with the EAC on compared to off, yielding slightly negative pollutant removal efficiencies (albeit largely within propagated uncertainty) and (ii) there was a change in observed concentrations of one potential limonene degradation product, m/z 59 (putatively identified as acetone), with steady-state levels increasing from 10 ppb (air cleaner off) to 15 ppb (air cleaner on). No increases or decreases beyond measurement uncertainty were observed for other analyzed gaseous limonene degradation products. Overall, both chamber and laboratory tests demonstrated negligible effectiveness of this device at the test conditions described herein for removing particles and mixed results for VOCs, including decreases in some VOCs, no discernible differences in other VOCs, and apparent increases in other compounds, especially lower molecular weight aldehydes including acetaldehyde
Control of milk pasteurization process using model predictive approach
YesA milk pasteurization process, a nonlinear process and multivariable interacting system, is difficult to control by the conventional on-off controllers since the on-off controller can handled the temperature profiles for milk and water oscillating over the plant requirements. The multi-variable control approach with model predictive control (MPC) is proposed in this study. The proposed algorithm was tested for control of a milk pasteurization process in three cases of simulation such as set point tracking, model mismatch, difference control and prediction horizons, and time sample. The results for the proposed algorithm show the well performance in keeping both the milk and water temperatures at the desired set points without any oscillation and overshoot and giving less drastic control action compared to the cascade generic model control (GMC) strategy
Economic MPC with a contractive constraint for nonlinear systems
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134956/1/rnc3549.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134956/2/rnc3549_am.pd
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A radiative cooling structural material.
Reducing human reliance on energy-inefficient cooling methods such as air conditioning would have a large impact on the global energy landscape. By a process of complete delignification and densification of wood, we developed a structural material with a mechanical strength of 404.3 megapascals, more than eight times that of natural wood. The cellulose nanofibers in our engineered material backscatter solar radiation and emit strongly in mid-infrared wavelengths, resulting in continuous subambient cooling during both day and night. We model the potential impact of our cooling wood and find energy savings between 20 and 60%, which is most pronounced in hot and dry climates
Deploying and Optimizing Embodied Simulations of Large-Scale Spiking Neural Networks on HPC Infrastructure
Simulating the brain-body-environment trinity in closed loop is an attractive proposal to investigate how perception, motor activity and interactions with the environment shape brain activity, and vice versa. The relevance of this embodied approach, however, hinges entirely on the modeled complexity of the various simulated phenomena. In this article, we introduce a software framework that is capable of simulating large-scale, biologically realistic networks of spiking neurons embodied in a biomechanically accurate musculoskeletal system that interacts with a physically realistic virtual environment. We deploy this framework on the high performance computing resources of the EBRAINS research infrastructure and we investigate the scaling performance by distributing computation across an increasing number of interconnected compute nodes. Our architecture is based on requested compute nodes as well as persistent virtual machines; this provides a high-performance simulation environment that is accessible to multi-domain users without expert knowledge, with a view to enable users to instantiate and control simulations at custom scale via a web-based graphical user interface. Our simulation environment, entirely open source, is based on the Neurorobotics Platform developed in the context of the Human Brain Project, and the NEST simulator. We characterize the capabilities of our parallelized architecture for large-scale embodied brain simulations through two benchmark experiments, by investigating the effects of scaling compute resources on performance defined in terms of experiment runtime, brain instantiation and simulation time. The first benchmark is based on a large-scale balanced network, while the second one is a multi-region embodied brain simulation consisting of more than a million neurons and a billion synapses. Both benchmarks clearly show how scaling compute resources improves the aforementioned performance metrics in a near-linear fashion. The second benchmark in particular is indicative of both the potential and limitations of a highly distributed simulation in terms of a trade-off between computation speed and resource cost. Our simulation architecture is being prepared to be accessible for everyone as an EBRAINS service, thereby offering a community-wide tool with a unique workflow that should provide momentum to the investigation of closed-loop embodiment within the computational neuroscience community.journal articl
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