856 research outputs found
Investigating the impact of actual and modeled occupant behavior information input to building performance simulation
© 2021 by the authors. Licensee MDPI, Basel, Switzerland. Occupant behaviors are one of the most dominant factors that influence building energy use. Understanding the influences from building occupants can promote the development of energy- efficient buildings. This paper quantifies the impact of different occupant behavior information on building energy model (BEM) from multiple perspectives. For this purpose, an occupant behavior model that uses agent-based modeling (ABM) approach is implemented via co-simulation with a BEM of an existing commercial building. Then, actual occupant behavior data in correspondence to ABM output, including operations on window, door, and blinds in selected thermal zones of the building are recorded using survey logs. A simulation experiment is conducted by creating three BEMs with constant, actual, and modeled occupant behavioral inputs. The analysis of the simulation results among these scenarios helps us gain an in-depth understanding of how occupant behaviors influence building performance. This study aims to facilitate robust building design and operation with human-in-the-loop system optimization
A flood damage allowance framework for coastal protection with deep uncertainty in sea-level rise
Future projections of Antarctic ice sheet (AIS) mass loss remain
characterized by deep uncertainty (i.e., behavior is not well understood or
widely agreed upon by experts). This complicates decisions on long-lived
projects involving the height of coastal flood protection strategies that seek
to reduce damages from rising sea levels. If a prescribed margin of safety does
not properly account for sea-level rise and its uncertainties, the
effectiveness of flood protection will decrease over time, potentially putting
lives and property at greater risk. We develop a flood damage allowance
framework for calculating the height of a flood protection strategy needed to
ensure that a given level of financial risk is maintained (i.e., the average
flood damage in a given year). The damage allowance framework considers
decision-maker preferences such as planning horizons, preferred protection
strategies (storm surge barrier, levee, elevation, and coastal retreat), and
subjective views of AIS stability. We use Manhattan (New York City)\textemdash
with the distribution of buildings, populations, and infrastructure fixed in
time\textemdash as an example to show how our framework could be used to
calculate a range of damage allowances based on multiple plausible AIS
outcomes. Assumptions regarding future AIS stability more strongly influence
damage allowances under high greenhouse gas emissions (Representative
Concentration Pathway [RCP] 8.5) compared to those that assume strong emissions
reductions (RCP2.6). Design tools that specify financial risk targets, such as
the average flood damage in a given year, allow for the calculation of avoided
flood damages (i.e., benefits) that can be combined with estimates of
construction cost and then integrated into existing financial decision-making
tools, like benefit-cost or cost-effectiveness analyses
Hints of (trans-Planckian) asymptotic freedom in semiclassical cosmology
We employ the semiclassical approximation to the Wheeler-DeWitt equation in
the spatially flat de Sitter Universe to investigate the dynamics of a
minimally coupled scalar field near the Planck scale. We find that, contrary to
naive intuition, the effects of quantum gravitational fluctuations become
negligible and the scalar field states asymptotically approach plane-waves at
very early times. These states can then be used as initial conditions for the
quantum states of matter to show that each mode essentially originated in the
minimum energy vacuum. Although the full quantum dynamics cannot be solved
exactly for the case at hand, our results can be considered as supporting the
general idea of asymptotic safety in quantum gravity.Comment: 11 pages, 2 figures; replaced to match content of published versio
Insulin Resistance and Body Fat Distribution in South Asian Men Compared to Caucasian Men
South Asians are susceptible to insulin resistance even without obesity. We examined the characteristics of body fat content, distribution and function in South Asian men and their relationships to insulin resistance compared to Caucasians.Twenty-nine South Asian and 18 Caucasian non-diabetic men (age 27+/-3 and 27+/-3 years, respectively) underwent euglycemic-hyperinsulinemic clamp for insulin sensitivity, underwater weighing for total body fat, MRI of entire abdomen for intraperitoneal (IP) and subcutaneous abdominal (SA) fat and biopsy of SA fat for adipocyte size.Compared to Caucasians, in spite of similar BMI, South Asians had higher total body fat (22+/-6 and 15+/-4% of body weight; p-value<0.0001), higher SA fat (3.5+/-1.9 and 2.2+/-1.3 kg, respectively; p-value = 0.004), but no differences in IP fat (1.0+/-0.5 and 1.0+/-0.7 kg, respectively; p-value = 0.4). SA adipocyte cell size was significantly higher in South Asians (3491+/-1393 and 1648+/-864 microm2; p-value = 0.0001) and was inversely correlated with both glucose disposal rate (r-value = -0.57; p-value = 0.0008) and plasma adiponectin concentrations (r-value = -0.71; p-value<0.0001). Adipocyte size differences persisted even when SA was matched between South Asians and Caucasians.Insulin resistance in young South Asian men can be observed even without increase in IP fat mass and is related to large SA adipocytes size. Hence ethnic excess in insulin resistance in South Asians appears to be related more to excess truncal fat and dysfunctional adipose tissue than to excess visceral fat
Changes in hydrodynamic, structural and geochemical properties in carbonate rock samples due to reactive transport
Reactive transport plays an important role in the development of a wide range of both anthropic and natural processes affecting geological media. To predict the consequences of reactive transport processes on structural and hydrodynamic properties of a porous media at large time and spatial scales, numerical modeling is a powerful tool. Nevertheless, such models, to be realistic, need geochemical, structural and hydrodynamic data inputs representative of the studied reservoir or material. Here, we present an experimental study coupling traditional laboratory measurements and percolation experiments in order to obtain the parameters that define rock heterogeneity, which can be altered during the percolation of a reactive fluid. In order to validate the experimental methodology and identify the role of the initial heterogeneities on the localization of the reactive transport processes, we used three different limestones with different petrophysical characteristics. We tracked the changes of geochemical, structural and hydrodynamic parameters in these samples induced by the percolation of an acid fluid by measuring, before and after the percolation experiment, petrophysical and hydrodynamic properties of the rocks.Peer ReviewedPostprint (published version
Customized chitooligosaccharide production—controlling their length via engineering of rhizobial chitin synthases and the choice of expression system
Chitooligosaccharides (COS) have attracted attention from industry and academia in various fields due to their diverse bioactivities. However, their conventional chemical production is environmentally unfriendly and in addition, defined and pure molecules are both scarce and expensive. A promising alternative is the in vivo synthesis of desired COS in microbial platforms with specific chitin synthases enabling a more sustainable production. Hence, we examined the whole cell factory approach with two well-established microorganisms—Escherichia coli and Corynebacterium glutamicum—to produce defined COS with the chitin synthase NodC from Rhizobium sp. GRH2. Moreover, based on an in silico model of the synthase, two amino acids potentially relevant for COS length were identified and mutated to direct the production. Experimental validation showed the influence of the expression system, the mutations, and their combination on COS length, steering the production from originally pentamers towards tetramers or hexamers, the latter virtually pure. Possible explanations are given by molecular dynamics simulations. These findings pave the way for a better understanding of chitin synthases, thus allowing a more targeted production of defined COS. This will, in turn, at first allow better research of COS’ bioactivities, and subsequently enable sustainable large-scale production of oligomers
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