5,703 research outputs found
Exploiting Decays at the Upgraded Fermilab Tevatron
We study the observability of a Standard Model-like Higgs boson at an
upgraded Fermilab Tevatron via the mode . We concentrate on the
main channel . We also find the mode
useful. We perform
detector level simulations by making use of a Monte Carlo program SHW.
Optimized searching strategy and kinematical cuts are developed. We find that
with a c.m. energy of 2 TeV and an integrated luminosity of 30 fb the
signal should be observable at a 3 level or better for the mass range
of 145 GeV < m_h < 180 GeV. For 95% confidence level exclusion, the mass reach
is 135 GeV < m_h <190 GeV. We also present results of studying these channels
with a model-independent parameterization. Further improvement is possible by
including other channels. We conclude that the upgraded Fermilab Tevatron will
have the potential to significantly advance our knowledge of Higgs boson
physics.Comment: 23 pages; 15 figures; 5 table
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Analysis of Down syndrome failed to be diagnosed after prenatal screening: A multicenter study.
To analyze the characters of Down syndrome (DS) who failed to be diagnosed after prenatal screening and hope to be able to improve the programs of prenatal screening and reduce the missed diagnosis of DS. In this multicenter study, we collected the missed cases from 3 prenatal diagnosis centers and analyzed their characters. A total of 126 DS babies failed to be diagnosed after prenatal screening. Their mothers accepted the prenatal screening in second trimester. We collected the mothers' blood and detected the levels of alpha-fetoprotein (AFP) and the free beta subunit of human chorionic gonadotropin (fβhCG) by time-resolved fluoroimmunoassay. The values were also presented as multiples of the median (MoM) and determined the risk of carrying a fetus with DS by Wallace LifeCycle Elipse analysis software. Compared with normal control group, the level of fβhCG and hCG MoM were dramatically increased, while AFP and AFP MoM were decreased. The area under the receiver-operating-characteristic curve of trisomy 21 was 0.8387 for hCG-MoM and AFP-MoM testing. The sensitivity, specificity, positive predictive value, and negative predictive value were 84.6%, 74.8%, 75.4%, and 83.6%, respectively. Meanwhile, the prediction mode was "0.39957 + 1.90897HCG-MOM -3.32713AFP-MOM". It was worthwhile noting that the risk of 65.9% DS missed diagnosis group were higher than 1/1000, 92.9% higher than 1/3000. However, 72.5% cases in normal control group were lower than 1/3000. Only 9.2% mothers would be higher than the value of risk in 1/1000. The prediction mode of hCG MoM and AFP MoM might be able to help us reduce the missed diagnosis. It is also necessary to adjust more reasonable range of noninvasive prenatal testing with further clinical researches
Research on a special scarifier mechanism with finite element analysis method
Abstract—A scarifier mechanism with rotary tillage and antirotary grubbing is proposed for inducing the power of tillage in hardens soil. MAT147 material modal is amended by experimental method and soil high-speed cutting finite element modal is build through SPH method, further, the tools parameter of proposed mechanism and soil cutting speed are studied by FEA numerical simulation through orthogonal experiments method. Finally, the result shows that the proposed mechanism with proper structural parameters and work speeds can reduce the requirement of power of tillage and increase the working efficiency of small agricultural machinery
Flashlight Search Medial Axis: A Pixel-Free Pore-Network Extraction Algorithm
Pore-network models (PNMs) have become an important tool in the study of
fluid flow in porous media over the last few decades, and the accuracy of their
results highly depends on the extraction of pore networks. Traditional methods
of pore-network extraction are based on pixels and require images with high
quality. Here, a pixel-free method called the flashlight search medial axis
(FSMA) algorithm is proposed for pore-network extraction in a continuous space.
The search domain in a two-dimensional space is a line, whereas a surface
domain is searched in a three-dimensional scenario. Thus, the FSMA algorithm
follows the dimensionality reduction idea; the medial axis can be identified
using only a few points instead of calculating every point in the void space.
In this way, computational complexity of this method is greatly reduced
compared to that of traditional pixel-based extraction methods, thus enabling
large-scale pore-network extraction. Based on cases featuring two- and
three-dimensional porous media, the FSMA algorithm performs well regardless of
the topological structure of the pore network or the positions of the pore and
throat centers. This algorithm can also be used to examine both closed- and
open-boundary cases. Finally, the FSMA algorithm can search dead-end pores,
which is of great significance in the study of multiphase flow in porous media
Technology transition from traditional oil and gas reservoir simulation to the next generation energy development
Energy transition has been a focus in both scientific research and social concerns in the past decade, thanks to the urgent need of reducing carbon emissions, slowing down the abnormal speed of global climate and achieving a balance between environmental protection and economic development. Although the global energy sector is shifting from the fossil-based energy systems, including oil and gas, to the renewable energy resources like hydrogen, the necessity of conventional energy development has received increasing attentions with regard to the stable supply and maturely developed technologies. The long-history simulation techniques developed for oil and gas reservoir investigations have enabled the deeper explorations into reservoir properties and enhanced significantly the resource recovery. As a main direction in energy transition, the development of hydrogen energy is profoundly influencing the long-term reconstruction of the world’s energy supply and application system, and is accelerating the transition and generational evolution in the fields of transportation, power generation, chemicals, and housing. In this paper, three research directions are proposed as the potential focus of technology transition, where traditional oil and gas reservoir simulation technologies can be adjusted and improved to be used to benefit the development of hydrogen energy.Cited as: Zhang, T., Liu, J., Sun, S. Technology transition from traditional oil and gas reservoir simulation to the next generation energy development. Advances in Geo-Energy Research, 2023, 7(1): 69-70. https://doi.org/10.46690/ager.2023.01.0
Stability analysis of the water bridge in organic shale nanopores: A molecular dynamic study
In the last decades, shale gas development has relieved the global energy crisis and slowed global warming problems. The water bridge plays an important role in the process of shale gas diffusion, but the stability of the water bridge in the shale nanochannel has not been revealed. In this work, the molecular dynamics method is applied to study the interaction between shale gas and water bridge, and the stability can be tested accordingly. CO2 can diffuse into the liquid H2O phase, but CH4 only diffuses at the boundary of the H2O phase. Due to the polarity of H2O molecules, the water bridge presents the wetting condition according to model snapshots and one-dimensional analyses, but the main body of the water bridge in the two-dimensional contour shows the non-wetting condition, which is reasonable. Due to the effect of the molecular polarity, CO2 prefers to diffuse into kerogen matrixes and the bulk phase of water bridge. In the bulk of the water bridge, where the interaction is weaker, CO2 has a lower energy state, implies that it has a good solubility in the liquid H2O phase. Higher temperature does not facilitate the diffusion of CO2 molecules, and higher pressure brings more CO2 molecules and enhances the solubility of CO2 in the H2O phase, in addition, a larger ratio of CO2 increases its content, which does the same effects with higher pressures. The stability of the water bridge is disturbed by diffused CO2 , and its waist is the weakest position by the potential energy distribution.Cited as:Â Liu, J., Zhang, T., Sun, S. Stability analysis of the water bridge in organic shale nanopores: A molecular dynamic study. Capillarity, 2022, 5(4): 75-82. https://doi.org/10.46690/capi.2022.04.0
The largest virialized dark halo in the universe
Using semi-analytic approach, we present an estimate of the properties of the
largest virialized dark halos in the present universe for three different
scenarios of structure formation: SCDM, LCDM and OCDM models. The resulting
virial mass and temperature increase from the lowest values of and 9.8 keV in OCDM, the mid-range values of and 31 keV in LCDM, to the highest values of
, 65 keV in SCDM. As compared with the
largest virialized object seen in the universe, the richest clusters of
galaxies, we can safely rule out the OCDM model. In addition, the SCDM model is
very unlikely because of the unreasonably high virial mass and temperature. Our
computation favors the prevailing LCDM model in which superclusters may be
marginally regarded as dynamically-virialized systems.Comment: 5 pages, Accepted by Int. J. Mod. Phys.
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