44 research outputs found
The detection of possible -ray quasi-periodic modulation with 600 days from the blazar S2 0109+22
In this work, we analyzed the long term gamma-ray data by a Fermi Large Area
Telescope (Fermi-LAT) of blazar S2 0109+22, ranging from 2008 to 2023. The
quasi-periodic oscillations (QPOs) of blazars aided in investigating the
physical properties of internal supermassive black holes, the nature of
variability, and the underlying radiation mechanism. We employed four different
methods--Weighted Wavelet Z-transform, Lomb-Scargle periodogram, REDFIT and
phase folded light curve analysis, for searching QPO signals. Our analysis
identified a possible QPO behavior with a periodicity of 600 days in
November 2013 to January 2023 at a significance level of 3.5 . This QPO
signal sustained 9 years, corresponding to 5.6 cycles, which was in good
agreement with the previously observed of periodicity 657 days in radio.
We explained this phenomenon based on the accretion model and the lighthouse
effect, in a binary black hole system.Comment: 12 pages, 8 figures,3 tables,accepted for publication in PAS
Chronic kidney disease as a predictive factor for poor prognosis in traumatic brain injury among older adults: a case-control study
ObjectiveTraumatic brain injury (TBI) is a highly prevalent neurological disorder that affects a gradually increasing proportion of older adults. Chronic kidney disease (CKD) significantly contributes to global years of life lost, with an estimated one-tenth of the global population affected by CKD. However, it remains unclear whether CKD impacts TBI prognosis. We conducted a case-control study to investigate the clinical outcomes of TBI patients with or without CKD comorbidity and identified the risk factors associated with a poor prognosis.MethodsFrom January 2017 through April 2023, 11 patients with TBI and CKD were included, and 27 control TBI cases with normal kidney function were matched by age, gender, and admission Glasgow Coma Scale (GCS) score as the control group.ResultsThe CKD TBI group had a significantly lower GCS score upon discharge (7.1 ± 5.9) compared to the non-CKD TBI group (13.1 ± 2.6) (p < 0.01). ICU stay time and hospitalization expenses were higher in the CKD group than the non-CKD group, though there were no statistical differences. Additionally, patients in the CKD TBI group had a higher frequency of hospital-acquired infections (54.4%) compared with those in the non-CKD TBI group (7.4%) (p < 0.01). The two groups exhibited no differences in hemoglobin levels, albumin levels, or coagulation function. Logistic regression analysis showed that advanced age, low admission GCS score, elevated blood urea, and creatinine levels were associated with a poor neurological prognosis.ConclusionTBI patients comorbid with CKD have a poorer prognosis than those with normal kidney function
Fine-Grained Urban Flow Inference via Normalizing Flow (Student Abstract)
Fine-grained urban flow inference (FUFI) aims to infer the coarse-grained (CG) urban flow map to the corresponding fine-grained (FG) one, which plays an important role in efficient traffic monitoring and management in smart cities. In FUFI, the CG map can be obtained with only a small number of monitoring devices, greatly reducing the overhead of deploying devices and the costs of maintenance, labor, and electricity. Existing FUFI methods are mainly based on techniques from image super-resolution (SR) models, which cannot fully consider the influence of external factors and face the ill-posed problem in SR tasks. In this paper, we propose UFI-Flow, a novel approach for addressing the FUFI problem by learning the conditional distributions of CG and FG map pairs. Given the CG map and the latent variables, the corresponding FG map is inferred by invertible transformations. In addition, an augmented distribution fusion mechanism is further proposed to constrain the urban flow distribution within the influence of external factors. We provide a new large-scale real-world FUFI dataset and show that UFI-Flow significantly outperforms the strong baselines
A Model for Energy Consumption of Main Cutting Force of High Energy Efficiency Milling Cutter under Vibration
Understanding the influence of the main cutting force energy consumption of the milling cutter is the basis for prediction and control of energy and machining efficiency. The existing models of cutting force energy consumption lack variables related to milling vibration and cutter teeth errors. According to the instantaneous bias of the main profile of the milling cutter under vibration, the instantaneous cutting boundary of the cutter teeth was investigated. The energy consumption distribution of the instantaneous main cutting force of the cutter tooth was studied. The model for the energy consumption of the instantaneous main cutting force of the cutter tooth and the milling cutter were both developed. The formation of energy consumption of the dynamic main cutting force of a high energy efficiency milling cutter was researched. A method for identifying the time–frequency characteristics of the energy consumption of the main cutting force under vibration was proposed and verified by experiments
Effects of Annular Combustor Width on the Ethylene-Air Continuous Rotating Detonation
The realization and stable operation of Continuous Rotating Detonation (CRD) in the annular combustor fueled by hydrocarbon-air are still challenging. For further investigation of this issue, a series of ethylene-air CRD tests with the variation of combustor width is conducted, and the effects of combustor width are well analyzed based on high-frequency pressure and high-speed photograph images. The results show that the combustor width plays a significant role in the realization and sustainability of the ethylene-air CRD. In this paper, the critical combustor width for the CRD realization and stable single wave are 20 mm and 25 mm, respectively. In wide combustors, the backward-facing step at the combustor forepart makes the main flow slow down, and thus, the mixing quality is promoted. Besides, the pilot flame at the recirculation zone contributes to sustaining the CRD wave. As the width increases, the propagation mode changes from counter-rotating two-wave mode to single wave mode with higher propagation velocity and stability. The highest propagation velocity reaches 1325.56 m/s in the 40 mm wide combustor, accounting for 71.51% of the corresponding Chapman-Jouguet velocity. Despite large combustor volume, high combustor pressure is obtained in detonation combustion mode indicating that a better propulsive performance could be achieved by CRD
An efficient and flexible host-FPGA PCIe communication library
A high-performance interconnection between a host processor and FPGA accelerators is in much demand. Among various interconnection methods, a PCIe bus is an attractive choice for loosely coupled accelerators. Because there is no standard host-FPGA communication library, FPGA developers have to write significant amounts of PCIe related code at both the FPGA side and the host processor side. A high-performance host-FPGA PCIe communication library holds the key to broadening the use of FPGA accelerators. In this paper we target efficiency and flexibility as two important features in such a library. We discuss the challenges in providing these features, and present our solution to these challenges. We propose EPEE, an efficient and flexible host-FPGA PCIe communication library and describe its design. We implemented EPEE in various generations of Xilinx FPGAs with up to 26.24 Gbps half-duplex and 43.02 Gbps full-duplex aggregate throughput in the PCIe Gen2 X8 mode; these are at the best utilization levels that a host-FPGA PCIe library can achieve. The EPEE library has been integrated into four different FPGA applications with different data usage patterns in various institutes.EI