343 research outputs found
Matrix Li-Yau-Hamilton Estimates under K\"ahler-Ricci Flow
We prove matrix Li-Yau-Hamilton estimates for positive solutions to the heat
equation and the backward conjugate heat equation, both coupled with the
K\"ahler-Ricci flow. As an application, we obtain a monotonicity formula.Comment: 13 pages. Comments are welcom
Trend-Based SAC Beam Control Method with Zero-Shot in Superconducting Linear Accelerator
The superconducting linear accelerator is a highly flexiable facility for
modern scientific discoveries, necessitating weekly reconfiguration and tuning.
Accordingly, minimizing setup time proves essential in affording users with
ample experimental time. We propose a trend-based soft actor-critic(TBSAC) beam
control method with strong robustness, allowing the agents to be trained in a
simulated environment and applied to the real accelerator directly with
zero-shot. To validate the effectiveness of our method, two different typical
beam control tasks were performed on China Accelerator Facility for Superheavy
Elements (CAFe II) and a light particle injector(LPI) respectively. The orbit
correction tasks were performed in three cryomodules in CAFe II seperately, the
time required for tuning has been reduced to one-tenth of that needed by human
experts, and the RMS values of the corrected orbit were all less than 1mm. The
other transmission efficiency optimization task was conducted in the LPI, our
agent successfully optimized the transmission efficiency of radio-frequency
quadrupole(RFQ) to over within 2 minutes. The outcomes of these two
experiments offer substantiation that our proposed TBSAC approach can
efficiently and effectively accomplish beam commissioning tasks while upholding
the same standard as skilled human experts. As such, our method exhibits
potential for future applications in other accelerator commissioning fields
Robust Automatic Focus Algorithm for Low Contrast Images Using a New Contrast Measure
Low contrast images, suffering from a lack of sharpness, are easily influenced by noise. As a result, many local false peaks may be generated in contrast measurements, making it difficult for the camera’s passive auto-focus system to perform its function of locating the focused peak. In this paper, a new passive auto-focus algorithm is proposed to address this problem. First, a noise reduction preprocessing is introduced to make our algorithm robust to both additive noise and multiplicative noise. Then, a new contrast measure is presented to bring in local false peaks, ensuring the presence of a well defined focused peak. In order to gauge the performance of our algorithm, a modified peak search algorithm is used in the experiments. The experimental results from an actual digital camera validate the effectiveness of our proposed algorithm
Heavy Metals Migration in Soil in Tailing Dam Region of Shuikoushan, Hunan Province, China
AbstractThe nonferrous mining industry in China has been exploiting rich domestic mineral resources in order to sustain rapidly economic and social development. The paper chooses the tailing dam region as the research object in the Shuikoushan, and researches the distribution of Pb, Zn, Cu, Cd, As, Cr, which reveals heavy metal migration regularities in layers from new and old tailing dam region. In addition, this article focuses on making the research of Potential Ecological Risk Index appraisal to the heavy metal contamination level. The results showed that the concentrations of heavy metals in old tailing dam region were much higher than those of in the new tailing dam region. As well, the concentrations of most heavy metal reduced progressively with the soil depth increasing for the new tailing dam region, while the change tendency was inversely for the old one. Potential ecological risk index showed that the potential ecological risks were at low and low to moderate level in tailing dam region
Exploring techniques for vision based human activity recognition: Methods, systems, and evaluation
With the wide applications of vision based intelligent systems, image and video analysis technologies have attracted the attention of researchers in the computer vision field. In image and video analysis, human activity recognition is an important research direction. By interpreting and understanding human activity, we can recognize and predict the occurrence of crimes and help the police or other agencies react immediately. In the past, a large number of papers have been published on human activity recognition in video and image sequences. In this paper, we provide a comprehensive survey of the recent development of the techniques, including methods, systems, and quantitative evaluation towards the performance of human activity recognitio
On Rough Hyperideals in Hyperlattices
We introduce and study rough hyperideals in hyperlattices. First, we give some interesting examples of hyperlattices and introduce hyperideals of hyperlattices. Then, applying the notion of rough sets to hyperlattices, we introduce rough hyperideals in hyperlattices, which are extended notions of hyperideals of hyperlattices. In addition, we consider rough hyperideals in Cartesian products and quotients of hyperlattices. Finally, we investigate some properties about homomorphic images of rough hyperideals in hyperlattices
Evolutionary Stages and Disk Properties of Young Stellar Objects in the Perseus Cloud
We investigated the evolutionary stages and disk properties of 211 Young
stellar objects (YSOs) across the Perseus cloud by modeling the broadband
optical to mid-infrared (IR) spectral energy distribution (SED). By exploring
the relationships among the turnoff wave bands lambda_turnoff (longward of
which significant IR excesses above the stellar photosphere are observed), the
excess spectral index alpha_excess at lambda <~ 24 microns, and the disk inner
radius R_in (from SED modeling) for YSOs of different evolutionary stages, we
found that the median and standard deviation of alpha_excess of YSOs with
optically thick disks tend to increase with lambda_turnoff, especially at
lambda_turnoff >= 5.8 microns, whereas the median fractional dust luminosities
L_dust/L_star tend to decrease with lambda_turnoff. This points to an
inside-out disk clearing of small dust grains. Moreover, a positive correlation
between alpha_excess and R_in was found at alpha_excess > ~0 and R_in > ~10
the dust sublimation radius R_sub, irrespective of lambda_turnoff,
L_dust/L_star and disk flaring. This suggests that the outer disk flaring
either does not evolve synchronously with the inside-out disk clearing or has
little influence on alpha_excess shortward of 24 microns. About 23% of our YSO
disks are classified as transitional disks, which have lambda_turnoff >= 5.8
microns and L_dust/L_star >10^(-3). The transitional disks and full disks
occupy distinctly different regions on the L_dust/L_star vs. alpha_excess
diagram. Taking L_dust/L_star as an approximate discriminator of disks with
(>0.1) and without (<0.1) considerable accretion activity, we found that 65%
and 35% of the transitional disks may be consistent with being dominantly
cleared by photoevaporation and dynamical interaction respectively. [abridged]Comment: 31 pages, 13 figures, 2 tables. To appear in a special issue of RAA
on LAMOST science
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