2,898 research outputs found
Phenomenological Modeling of Infrared Sources: Recent Advances
Infrared observations from planned space facilities (e.g., ISO (Infrared Space Observatory), SIRTF (Space Infrared Telescope Facility)) will yield a large and uniform sample of high-quality data from both photometric and spectroscopic measurements. To maximize the scientific returns of these space missions, complementary theoretical studies must be undertaken to interpret these observations. A crucial step in such studies is the construction of phenomenological models in which we parameterize the observed radiation characteristics in terms of the physical source properties. In the last decade, models with increasing degree of physical realism (in terms of grain properties, physical processes, and source geometry) have been constructed for infrared sources. Here we review current capabilities available in the phenomenological modeling of infrared sources and discuss briefly directions for future research in this area
FAST polarization mapping of the SNR VRO 42.05.01
We have obtained the polarization data cube of the VRO 42.05.01 supernova
remnant at 1240 MHz using the Five-hundred-meter Aperture Spherical radio
Telescope (FAST). Three-dimensional Faraday Synthesis is applied to the FAST
data to derive the Faraday depth spectrum. The peak Faraday depth map shows a
large area of enhanced foreground RM of ~60 rad m-2 extending along the
remnant's "wing" section, which coincides with a large-scale HI shell at -20
km/s. The two depolarization patches within the "wing" region with RM of 97 rad
m-2 and 55 rad m-2 coincide with two HI structures in the HI shell. Faraday
screen model fitting on the Canadian Galactic Plane Survey (CGPS) 1420 MHz
full-scale polarization data reveals a distance of 0.7-0.8d_{SNR} in front of
the SNR with enhanced regular magnetic field there. The highly piled-up
magnetic field indicates that the HI shell at -20 km/s could originate from an
old evolved SNR.Comment: 9 pages, 8 figures, accepted by Ap
Melanoma-associated retinopathy
AbstractA 63-year-old Taiwanese man with a history of cutaneous melanoma presented with a rapid onset of bilateral shimmering light and blurred vision. A fundoscopic examination was normal. However, visual field examination indicated generalized depression in both eyes. Scotopic rod-specific electroretinography (ERG) was undetectable and scotopic maximal combined-cone and rod-specific ERG showed the characteristics of negative ERG (a normal a-wave and a diminished b-wave, with the b-wave smaller than the a-wave), indicating dysfunction of the bipolar cells. Melanoma-associated retinopathy (MAR) was suspected and a systemic work-up gave a diagnosis of metastatic melanoma. This case shows the typical presentation of MAR. Greater awareness of MAR in patients with unexplained visual loss may help to identify an occult focus of metastatic melanoma
Application of Neural-Like P Systems With State Values for Power Coordination of Photovoltaic/Battery Microgrids
The power coordination control of a photovoltaic/battery microgrid is performed with a novel
bio-computing model within the framework of membrane computing. First, a neural-like P system with
state values (SVNPS) is proposed for describing complex logical relationships between different modes
of Photovoltaic (PV) units and energy storage units. After comparing the objects in the neurons with the
thresholds, state values will be obtained to determine the con guration of the SVNPS. Considering the
characteristics of PV/battery microgrids, an operation control strategy based on bus voltages of the point of
common coupling and charging/discharging statuses of batteries is proposed. At rst, the SVNPS is used to
construct the complicated unit working modes; each unit of the microgrid can adjust the operation modes
automatically. After that, the output power of each unit is reasonably coordinated to ensure the operation
stability of the microgrid. Finally, a PV/battery microgrid, including two PV units, one storage unit, and
some loads are taken into consideration, and experimental results show the feasibility and effectiveness of
the proposed control strategy and the SVNPS-based power coordination control models
Diffusion Model-Augmented Behavioral Cloning
Imitation learning addresses the challenge of learning by observing an
expert's demonstrations without access to reward signals from environments.
Most existing imitation learning methods that do not require interacting with
environments either model the expert distribution as the conditional
probability p(a|s) (e.g., behavioral cloning, BC) or the joint probability p(s,
a) (e.g., implicit behavioral cloning). Despite its simplicity, modeling the
conditional probability with BC usually struggles with generalization. While
modeling the joint probability can lead to improved generalization performance,
the inference procedure can be time-consuming and it often suffers from
manifold overfitting. This work proposes an imitation learning framework that
benefits from modeling both the conditional and joint probability of the expert
distribution. Our proposed diffusion model-augmented behavioral cloning (DBC)
employs a diffusion model trained to model expert behaviors and learns a policy
to optimize both the BC loss (conditional) and our proposed diffusion model
loss (joint). DBC outperforms baselines in various continuous control tasks in
navigation, robot arm manipulation, dexterous manipulation, and locomotion. We
design additional experiments to verify the limitations of modeling either the
conditional probability or the joint probability of the expert distribution as
well as compare different generative models
Superradiant Solid in Cavity QED Coupled to a Lattice of Rydberg Gas
We study an optical cavity coupled to a lattice of Rydberg atoms, which can
be represented by a generalized Dicke model. We show that the competition
between the atomic interaction and atom-light coupling induces a rich phase
diagram. A novel "superradiant solid" (SRS) phase is found, where both the
superradiance and crystalline orders coexist. Different from the normal second
order superradiance (SR) transition, here both the Solid-1/2 and SRS to SR
phase transitions are first order. These results are confirmed by the large
scale quantum Monte Carlo simulations.Comment: 5 pages,4 figure
Study on the experiment and reaction kinetics of sulfur removal from coal by microorganisms
To solve the safety problem of spontaneous combustion of high-sulfur coal, applied microbiology, physical chemistry, reaction kinetics theory, combined with the SEM, FTIR and TG-DTG-DSC experiments and analysis of testing methods, the microbial desulfurization experiments were carried out, and the change law of the desulfurization reaction of coal before and after the element composition, main physical and chemical properties, the coal spontaneous combustion point was studied. The results show that when the temperature is 30°C, the coal particle size is 120 mesh, the initial pH value is 2.0 and the bacteria liquid amount is 15 mL, the desulfurization effect of the coal sample is the best, and the maximum desulfurization rate can reach 75.12%. There is obvious erosion on the surface of the coal sample after microbial desulfurization, the pyrite in the coal is obviously reduced, and the molecular structure in the coal is basically unchanged. Under the action of microorganism, part of inorganic sulfur in coal is removed, the spontaneous combustion point of coal is increased by 50°C, the activation energy of coal has increased more than three times, and the possibility of spontaneous combustion of coal is reduced. By analyzing the reaction kinetics of the microbial desulfurization process, it can be seen that the microbial desulfurization reaction is controlled by external diffusion, internal diffusion and chemical reaction, among which internal diffusion is the main influencing factor
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