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bstract
We study the azimuthal angular decorrelation of the dijet production via photon fusion in ultra-peripheral heavy ion collisions. The impact parameter dependent cross section of ...quark-antiquark pairs production is derived using the equivalent photon approximation, and the contribution from final-state QCD radiations to the azimuthal angular distribution are calculated within Soft-Collinear Effective Theory. We carry out the QCD resummation of large logarithms of the azimuthal angle as well as the jet radius at next-to-leading logarithmic accuracy. In the end we present the normalized differential cross section for azimuthal decorrelation of the dijet pair and find that our results are consistent with the measurements reported by the ATLAS collaboration.
•We used CE-3 LPR to estimate the permittivity of the regolith at landing site.•We applied a hyperbola matching and direct least-squares method.•No distinct boundary or layering was found in regolith ...after migration.•Regolith permittivity increases quickly with depth; regolith thickness is ∼2.5–3 m.
The second channel (CH2) of the Lunar Penetrating Radar (LPR) carried on the Chang'e-3 (CE-3) Yutu Rover was used to determine the thickness and structure of the lunar regolith. Accurately revealing the true structure beneath the surface requires knowledge of the dielectric permittivity of the regolith, which allows one to properly apply migration to the radar image. In contrast to simple assumptions in previous studies, this paper takes account of heterogeneity of the regolith and derives regolith's permittivity distribution laterally and vertically by a method widely used in data processing of terrestrial Ground Penetrating Radar (GPR). We find that regolith permittivity at the landing site increases with depth more quickly than previously recognized. At a depth of ∼2.5–3 m, the dielectric constant reaches the value of solid basalt. The radar image was migrated on the basis of the permittivity profile. We do not find any continuous distinct layers or an apparent regolith/rock interface in the migrated radargram, which implies that this area is covered by relatively young, poorly layered deposits.
This article presents a CMOS-compatible low-power photonic demodulator for time-of-flight (ToF) CMOS image sensor. The proposed device called the junction-assisted photonic demodulator (JAPD) uses ...electric field applied through two guide electrodes to facilitate the collection of optically generated minority carriers but using a p-n junction to prevent direct majority carrier current. A prototype of the JAPD has been fabricated in a 0.18-<inline-formula> <tex-math notation="LaTeX">\mu </tex-math> </inline-formula>m standard CMOS foundry process. Experimental results show that it can achieve a low-power consumption of 29 fW per pixel and a high modulation contrast (MC) of 98%. Through process optimization, it is shown that the optical window can be fully depleted during the demodulation process. In TCAD simulation, the frequency response can be significantly improved by ensuring full depletion of the optical window.
China launched Tianwen-1 spacecraft successfully on July 23rd, 2020. The Mars Orbiter Subsurface Investigation Radar (MOSIR) is a subsurface radar sounder as a scientific instrument onboard Tianwen-1 ...orbiter. It is designed to study the compositions of Martian surface material, subsurface structure, and the ionosphere’s total electron content. It can also perform passive observations in a transfer orbit to Mars. The subsurface stratigraphic structure is critical to the study on Mars geological and climatic evolution history. Considering the optimal tradeoff between penetrating depth and range resolution, MOSIR operates at low-frequency and high-frequency channels, with the frequency bands of 10–15 MHz or 15–20 MHz and 30–50 MHz, respectively. MOSIR provides a penetration depth of more than 100 m with a vertical resolution of 7.5 m (20 MHz bandwidth) and 30 m (5 MHz bandwidth) in free space. The range and azimuth focusing techniques are applied in ground data processing to achieve the resolution of several hundred meters (along-track) and several thousand meters (cross-track). MOSIR is intended to search for water ice and liquid water that may be associated with signs of life in the polar layered deposits, Tianwen-1 landing site, and other selected areas.
Gas turbines operate under harsh conditions of high temperature and pressure for extended periods, inevitably experiencing performance degradation. Predicting the performance degradation trend of gas ...turbines and optimizing planned maintenance cycles are crucial for the economic and safety aspects of gas turbine operation. In this study, a novel data-driven approach for predicting gas turbine performance degradation is proposed. Initially, gas turbine operating data are augmented using a mechanism model. Subsequently, a data-driven performance model is constructed based on support vector regression (SVR) and gas turbine operational characteristics, enabling real-time calculation of performance degradation indicators. Building on this, an Autoregressive Neural Network (AR-Net) is employed to construct a model for predicting the trend of performance degradation. The proposed method is applied to predict performance degradation caused by fouling in the compressor of a gas turbine. Comparative analysis with three other performance degradation prediction methods indicates that the proposed approach accurately identifies the performance degradation trend of gas turbines, determining the optimal maintenance timing. This holds significant importance for the condition-based maintenance of gas turbines.
Chronic prostatitis and chronic pelvic pain syndrome (CP/CPPS), a prevalent urological ailment, exerts a profound influence upon the well‐being of the males. Autoimmunity driven by Th17 cells has ...been postulated as a potential factor in CP/CPPS pathogenesis. Nonetheless, elucidating the precise mechanisms governing Th17 cell recruitment to the prostate, triggering inflammation, remained an urgent inquiry. This study illuminated that CCL20 played a pivotal role in attracting Th17 cells to the prostate, thereby contributing to prostatitis development. Furthermore, it identified prostate stromal cells and immune cells as likely sources of CCL20. Additionally, this research unveiled that IL‐17A, released by Th17 cells, could stimulate macrophages to produce CCL20 through the NF‐κB/MAPK/PI3K pathway. The interplay between IL‐17A and CCL20 establishes a positive feedback loop, which might serve as a critical mechanism underpinning the development of chronic prostatitis, thus adding complexity to its treatment challenges.
The research on vital information extraction meets a lot challenges due to the narrow bandwidth and low signal-to-noise ratio of a vital sign in real environment. In this paper, a novel noncontract ...vital sign detection method based on multiple higher order cumulant is presented. According to the characteristic of vital sign for impulse ultrawideband radar, the quasi-periodic reflected echo in slow-time is analyzed. The novel method is theoretically deduced from fourth-order cumulant. It is proved to be better than the reference fast Fourier transform method by simulation and experiment. By using the new method, the range position and frequency information of life can be extracted accurately and automatically.
The Lunar Regolith Penetrating Radar (LRPR) onboard the Chang’E 5 lander is the first antenna-array radar deployed for the exploration of an extraterrestrial object. It is able to measure the ...subsurface structure of the moon at a resolution of ∼10 cm. This work presents a method for calibrating the variable cable delay of the LRPR and an imaging method based on synthesis imaging from Radio Astronomy. The cable delay calibration method effectively calibrates the cable delay shift of the LRPR with a nanosecond-level precision. To validate the accuracy of the cable delay method, we use the data obtained from both the ground experiment and the moon-exploration mission of the LRPR. The imaging method is used to visualize the subsurface structure of the Chang’E-5 (CE-5) landing site. Moreover, Finite-Difference Time-Domain (FDTD) simulation is carried out to help interpret the imaging results. The radar images derived from the LRPR observations show consistency with each other and match the bit force record during the drilling process. The results suggest that the rocks interacted with the CE-5 drill feature a size of 15 to 20 cm.
•We have developed a cable calibration method based on the LRPR designation.•We have proposed an imaging method to visualize the LRPR observations.•The performance of the LRPR and the imaging method is tested with FDTD simulation.•The buried rocks which interacted with the CE-5 drill feature a size of 15 to 20 cm.
Cloud computing is a recent trend in IT, which has attracted lots of attention. In cloud computing, service reliability and service performance are two important issues. To improve cloud service ...reliability, fault tolerance techniques such as fault recovery may be used, which in turn has impact on cloud service performance. Such impact deserves detailed research. Although there exist some researches on cloud/grid service reliability and performance, very few of them addressed the issues of fault recovery and its impact on service performance. In this paper, we conduct detailed research on performance evaluation of cloud service considering fault recovery. We consider recovery on both processing nodes and communication links. The commonly adopted assumption of Poisson arrivals of users’ service requests is relaxed, and the interarrival times of service requests can take arbitrary probability distribution. The precedence constraints of subtasks are also considered. The probability distribution of service response time is derived, and a numerical example is presented. The proposed cloud performance evaluation models and methods could yield results which are realistic, and thus are of practical value for related decision-makings in cloud computing.
In cloud computing, cloud service performance is an important issue. To improve cloud service reliability, fault recovery may be used. However, the use of fault recovery could have impact on the ...performance of cloud service. In this paper, we conduct a preliminary study on this issue. Cloud service performance is quantified by service response time, whose probability density function as well as the mean is derived.
