1,959 research outputs found
Opportunities for Stationary Fuel Cell Applications in Ohio: Public Finance and Other Strategies
Ohio has not, heretofore, been a major player in the deployment of stationary fuel cell applications, notwithstanding its status as a leader in developing fuel cell technology. One reason for this is that in the years since fuel cells became commercially available, fuel cell power generation had struggled to be cost effective in Ohio due to a combination low electricity prices and high natural gas prices, the latter being the most common fuel for stationary fuel cell applications.
By 2015, this had changed. The Mid-Atlantic region was enjoying the lowest natural gas prices in North America as a result of regional shale development. Meanwhile, wholesale electricity prices in the PJM Interconnect regional transmission organization (Mid-Atlantic region) are among the highest in the nation. This has created therein a historically high âspark spreadâ -- the term used to describe the price differential between wholesale natural gas and electricity. Whatâs more, fuel cell generation qualifies for net metering, and may be valued at retail costs. Finally, additional new value for the avoided costs of carbon and other emissions may be derived from new ultra-efficient fuel cell technologies.
As for other nascent technologies, early adoption will likely require public-private financing partnerships. There are available federal, state and local financing strategies to enable the deployment of fuel cells in Ohio. Loan programs such as the Energy Loan Fund and Qualified Energy Conservation Bonds can be used to support fuel cell demonstration with low interest loans. Property Assessed Clean Energy (PACE) bonds may also soon be available to support fuel cell deployment, depending upon pending Ohio legislation. In addition, the Public Utility Commission of Ohio has within its authority to support power purchase agreements or special arrangements for buyers to support generation that is in the interest of Ohio ratepayers (such as when it promotes economic development).
The best places to acquire natural gas for power generation on long-term, fixed prices will be at gathering points along the natural gas pipeline and processing system. Such points offer natural gas producers the most flexibility to supply natural gas long term. Most of the gathering and processing points are currently located in southeastern Ohio, however new interstate pipelines are being built across northern Ohio. This new infrastructure may provide opportunities to locate stationary fuel cells in the generation, transmission and capacity-constrained northern Ohio market.
Low gas prices may also provide opportunities for stationary fuel cell applications using low temperature fuel cells. Such fuel cells run directly on hydrogen, and heretofore, the costs of manufacturing, transporting and storing hydrogen has made the economics for such generation difficult. Low hydrogen feedstock costs, together with the ability low temperature fuel cells have to supply the lucrative peak loading market, may make such applications cost effective in the near term
Fast and Accurate Coarsening Simulation with an Unconditionally Stable Time Step
We present Cahn-Hilliard and Allen-Cahn numerical integration algorithms that
are unconditionally stable and so provide significantly faster
accuracy-controlled simulation. Our stability analysis is based on Eyre's
theorem and unconditional von Neumann stability analysis, both of which we
present. Numerical tests confirm the accuracy of the von Neumann approach,
which is straightforward and should be widely applicable in phase-field
modeling. We show that accuracy can be controlled with an unbounded time step
Delta-t that grows with time t as Delta-t ~ t^alpha. We develop a
classification scheme for the step exponent alpha and demonstrate that a class
of simple linear algorithms gives alpha=1/3. For this class the speed up
relative to a fixed time step grows with the linear size of the system as N/log
N, and we estimate conservatively that an 8192^2 lattice can be integrated 300
times faster than with the Euler method.Comment: 14 pages, 6 figure
The California Planet Survey IV: A Planet Orbiting the Giant Star HD 145934 and Updates to Seven Systems with Long-Period Planets
We present an update to seven stars with long-period planets or planetary
candidates using new and archival radial velocities from Keck-HIRES and
literature velocities from other telescopes. Our updated analysis better
constrains orbital parameters for these planets, four of which are known
multi-planet systems. HD 24040 b and HD 183263 c are super-Jupiters with
circular orbits and periods longer than 8 yr. We present a previously unseen
linear trend in the residuals of HD 66428 indicative on an additional planetary
companion. We confirm that GJ 849 is a multi-planet system and find a good
orbital solution for the c component: it is a planet in a 15 yr
orbit (the longest known for a planet orbiting an M dwarf). We update the HD
74156 double-planet system. We also announce the detection of HD 145934 b, a planet in a 7.5 yr orbit around a giant star. Two of our stars, HD
187123 and HD 217107, at present host the only known examples of systems
comprising a hot Jupiter and a planet with a well constrained period yr,
and with no evidence of giant planets in between. Our enlargement and
improvement of long-period planet parameters will aid future analysis of
origins, diversity, and evolution of planetary systems.Comment: 16 pages, 13 figures. Accepted for publication in Ap
Statesâ Support of Non-Highway Modes of Transportation: Investigation and Synthesis
The objective of this study was to determine how Kentucky and other selected states support and assist non-highway transportation modes and to identify leading and innovative initiatives. For the purposes of this study, the non-highway modes are aviation, public transportation, rail, and waterways. This summary will briefly discuss the rationale, objectives, and methodology for this study. It also provides an overview of the outcomes of the study and the modal matrices
Assessing the ability of human endothelial cells derived from inducedâpluripotent stem cells to form functional microvasculature in vivo
Forming functional blood vessel networks is a major clinical challenge in the fields of tissue engineering and therapeutic angiogenesis. Cellâbased strategies to promote neovascularization have been widely explored, but cell sourcing remains a significant limitation. Inducedâpluripotent stem cellâderived endothelial cells (iPSCâECs) are a promising, potentially autologous, alternative cell source. However, it is unclear whether iPSCâECs form the same robust microvasculature in vivo documented for other EC sources. In this study, we utilized a wellâestablished in vivo model, in which ECs (iPSCâEC or human umbilical vein endothelial cells [HUVEC]) were coinjected with normal human lung fibroblasts (NHLFs) and a fibrin matrix into the dorsal flank of severe combined immunodeficiency mice to assess their ability to form functional microvasculature. Qualitatively, iPSCâECs were capable of vessel formation and perfusion and demonstrated similar vessel morphologies to HUVECs. However, quantitatively, iPSCâECs exhibited a twoâfold reduction in vessel density and a threeâfold reduction in the number of perfused vessels compared with HUVECs. Further analysis revealed the presence of collagenâIV and αâsmooth muscle actin were significantly lower around iPSCâEC/NHLF vasculature than in HUVEC/NHLF implants, suggesting reduced vessel maturity. Collectively, these results demonstrate the need for increased iPSCâEC maturation for clinical translation to be realized.Forming functional blood vessel networks is a major clinical challenge in the fields of tissue engineering and therapeutic angiogenesis. Cellâbased strategies to promote neovascularization have been widely explored, but cell sourcing remains a significant limitation.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146963/1/bit26860.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146963/2/bit26860_am.pd
Spatio-Temporal Gap Analysis of OBIS-SEAMAP Project Data: Assessment and Way Forward
The OBIS-SEAMAP project has acquired and served high-quality marine mammal, seabird, and sea turtle data to the public since its inception in 2002. As data accumulated, spatial and temporal biases resulted and a comprehensive gap analysis was needed in order to assess coverage to direct data acquisition for the OBIS-SEAMAP project and for taxa researchers should true gaps in knowledge exist. All datasets published on OBIS-SEAMAP up to February 2009 were summarized spatially and temporally. Seabirds comprised the greatest number of records, compared to the other two taxa, and most records were from shipboard surveys, compared to the other three platforms. Many of the point observations and polyline tracklines were located in northern and central Atlantic and the northeastern and central-eastern Pacific. The Southern Hemisphere generally had the lowest representation of data, with the least number of records in the southern Atlantic and western Pacific regions. Temporally, records of observations for all taxa were the lowest in fall although the number of animals sighted was lowest in the winter. Oceanographic coverage of observations varied by platform for each taxa, which showed that using two or more platforms represented habitat ranges better than using only one alone. Accessible and published datasets not already incorporated do exist within spatial and temporal gaps identified. Other related open-source data portals also contain data that fill gaps, emphasizing the importance of dedicated data exchange. Temporal and spatial gaps were mostly a result of data acquisition effort, development of regional partnerships and collaborations, and ease of field data collection. Future directions should include fostering partnerships with researchers in the Southern Hemisphere while targeting datasets containing species with limited representation. These results can facilitate prioritizing datasets needed to be represented and for planning research for true gaps in space and time
Effective Temperatures of Low-Mass Stars from High-Resolution H-band Spectroscopy
High-resolution, near-infrared spectra will be the primary tool for finding
and characterizing Earth-like planets around low-mass stars. Yet, the
properties of exoplanets can not be precisely determined without accurate and
precise measurements of the host star. Spectra obtained with the Immersion
GRating INfrared Spectrometer (IGRINS) simultaneously provide diagnostics for
most stellar parameters, but the first step in any analysis is the
determination of the effective temperature. Here we report the calibration of
high-resolution H-band spectra to accurately determine effective temperature
for stars between 4000-3000 K (K8--M5) using absorption line depths of Fe
I, OH, and Al I. The field star sample used here contains 254 K and M stars
with temperatures derived using BT-Settl synthetic spectra. We use 106 stars
with precise temperatures in the literature to calibrate our method with
typical errors of about 140 K, and systematic uncertainties less than 120
K. For the broadest applicability, we present T--line-depth-ratio
relationships, which we test on 12 members of the TW Hydrae Association and at
spectral resolving powers between 10,000--120,000. These ratios offer a
simple but accurate measure of effective temperature in cool stars that is
distance and reddening independent.Comment: 19 pages, 11 figures and 3 tables. Accepted in Ap
A systematic review of the energy and climate impacts of teleworking
Information and communication technologies (ICTs) increasingly enable employees to work from home and other locations (âteleworkingâ). This study explores the extent to which teleworking reduces the need to travel to work and the consequent impacts on economy-wide energy consumption.
Methods/Design: The paper provides a systematic review of the current state of knowledge of the energy impacts of teleworking. This includes the energy savings from reduced commuter travel and the indirect impacts on energy consumption associated with changes in non-work travel and home energy consumption. The aim is to identify the conditions under which teleworking leads to a net reduction in economy-wide energy consumption, and the circumstances where benefits may be outweighed by unintended impacts. The paper synthesises the results of 39 empirical studies, identified through a comprehensive search of 9,000 published articles.
Review results/Synthesis: Twenty six of the 39 studies suggest that teleworking reduces energy use, and only eight studies suggest that teleworking increases, or has a neutral impact on energy use. However, differences in the methodology, scope and assumptions of the different studies make it difficult to estimate âaverageâ energy savings. The main source of savings is the reduced distance travelled for commuting, potentially with an additional contribution from lower office energy consumption. However, the more rigorous studies that include a wider range of impacts (e.g. non-work travel or home energy use) generally find smaller savings.
Discussion: Despite the generally positive verdict on teleworking as an energy-saving practice, there are numerous uncertainties and ambiguities about its actual or potential benefits. These relate to the extent to which teleworking may lead to unpredictable increases in non-work travel and home energy use that may outweigh the gains from reduced work travel. The available evidence suggests that economy-wide energy savings are typically modest, and in many circumstances could be negative or non-existent
Visual cortex anodal transcranial direct current stimulation does not alter reading performance for Chinese presented character-by-character to normal peripheral vision in older adults
Visual cortex anodal transcranial direct current stimulation (a-tDCS) has been shown to reduce crowding in normal peripheral vision and may improve the reading of English words in patients with macular degeneration. Given the different visual requirements of reading English words and Chinese characters, the effect of a-tDCS on peripheral reading performance in English might differ from Chinese. This study recruited 20 participants (59â73 years of age) with normal vision and tested the hypothesis that a-tDCS would improve the reading of Chinese characters presented at 10° eccentricity compared with sham stimulation. Chinese sentences of different print sizes and exposure durations were presented one character at a time, 10° below or to the left of fixation. The individual critical print size (CPS) â the smallest print size eliciting the maximum reading speed (MRS) â was determined. Reading accuracies for characters presented 0.2 logMAR smaller than the individually fitted CPS were measured at four time points: before, during, 5 min after, and 30 min after receiving active or sham visual cortex a-tDCS. Participants completed both the active and sham sessions in a random order following a double-blind, within-subject design. No effect of active a-tDCS on reading accuracy was observed, implying that a single session of a-tDCS did not improve Chinese character reading in normal peripheral vision. This may suggest that a-tDCS does not significantly reduce the crowding elicited within a single Chinese character. However, the effect of a-tDCS on between-character crowding is yet to be determined
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