138,621 research outputs found

    Experimental analysis of oil-water nuclear magnetic relaxation characteristics of complex conglomerate reservoir

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    The lithology and pore structure of conglomerate reservoir in the Mahu sag, China, are complex, which makes it difficult to identify reservoir fluids. In this study, the body relaxation characteristics of crude oil at different temperatures were obtained from block crude oil samples, and two simulated oil samples with different body relaxation characteristics were used to conduct experiments. The saturated water, bound water, and saturated oil states of some conglomerate samples were quickly established by vacuum compression saturation, high-speed centrifugation, and vacuum saturation simulation of oil, and the fluid and different simulated oil-water saturation states were analyzed by nuclear magnetic resonance (NMR) experiments. The experimental results showed that the distribution range of the water-saturated core NMR T2 spectrum is mainly affected by surface relaxation. The NMR spectra of saturated oil with different viscosity values are different from those of saturated water because of the relaxation property of the oil phase. The samples of this experiment indicated that the difference is more obvious when the oil is thinner. The distribution pattern of the oil-bearing NMR results was affected by the relaxation of the oil phase, surface relaxation, pore structure, and wettability. With consideration of the relaxation characteristics of the oil samples, the NMR T2 spectra of two oil-saturated conglomerates were analyzed by multi-component Gaussian fitting, and the relaxation signals of the oil phase were evaluated quantitatively

    An explicit approximation for super-linear stochastic functional differential equations

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    Since it is difficult to implement implicit schemes on the infinite-dimensional space, we aim to develop the explicit numerical method for approximating super-linear stochastic functional differential equations (SFDEs). Precisely, borrowing the truncation idea and linear interpolation we propose an explicit truncated Euler‚ÄďMaruyama (EM) scheme for SFDEs, and obtain the boundedness and convergence in Lp (p‚Č•2). We also prove the convergence rate with 1/2 order. Different from some previous works (Mao, 2003; Zhang et al., 2018), we release the global Lipschitz restriction on the diffusion coefficient. Furthermore, we reveal that numerical solutions preserve the underlying exponential stability. Moreover, we give several examples to support our theory

    Performance of the local reconstruction algorithms for the CMS hadron calorimeter with Run 2 data

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    A description is presented of the algorithms used to reconstruct energy deposited in the CMS hadron calorimeter during Run 2 (2015‚Äď2018) of the LHC. During Run 2, the characteristic bunch-crossing spacing for proton-proton collisions was 25 ns, which resulted in overlapping signals from adjacent crossings. The energy corresponding to a particular bunch crossing of interest is estimated using the known pulse shapes of energy depositions in the calorimeter, which are measured as functions of both energy and time. A variety of algorithms were developed to mitigate the effects of adjacent bunch crossings on local energy reconstruction in the hadron calorimeter in Run 2, and their performance is compared

    An empirical study on the response of university students to viewing autumn secondary forest phytocommunities landscape via virtual reality in Northeast China

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    Secondary forests play a critical role in the natural environment and have the potential to provide significant benefits for human physical and mental well-being. The secondary forests in the Sanhu National Nature Reserve, located in Northeast China, have extremely high ecological value. In this study, we selected seven types of secondary forest phytocommunities in this region, measured ecological indicators at various sites, and captured panoramic photos on-site. Virtual reality (VR) technology was used to present and record participants' electroencephalogram (EEG) data for studying neural activity. Statistical analyses were conducted using SPSS 26.0 to evaluate the data obtained from the study. The results showed that participants preferred landscapes predominantly consisting of mixed forests of Pinus koraiensis mixed broad-leaved forest (FP1.őĪ and FP2.őĪ: p¬†=¬†0.001), featuring colorful and verdant scenery. Experiencing these seven types of secondary forest landscapes through virtual reality improved participants' mood and had a positive impact on them. Within a certain range (300‚Äď400¬†m, 0-30¬į), participants favored landscapes with higher elevations (FP1.ő≤: p¬†=¬†0.008, FP2.ő≤: p¬†=¬†0.001, F3.ő≤: p¬†=¬†0.006) and gentler slopes (F3.őł: p¬†=¬†0.002, F4.őł: p¬†=¬†0.031, F8.őł: p¬†=¬†0.005). Additionally, participants showed a preference for secondary forest landscapes with a moderate canopy density ranging from 0.7 to 0.8 (FP1.őł: p¬†=¬†0.015, FP2.őł: p¬†=¬†0.014). The study also found that participants preferred landscapes with a greater abundance of trees and shrubs, as well as taller and narrower trees. Moreover, our study revealed that males favored autumn forest landscapes more than females, with graduate students showing a stronger preference compared to undergraduates. Urban residents also displayed a stronger preference for these landscapes over rural residents, and individuals from the Southern region expressed a higher inclination than their Northern counterparts (T3.őī: p¬†=¬†0.002, p¬†=¬†0.001 for others). These findings can provide reference for the design and plant arrangement of urban forest landscapes

    Design of TiO<sub>2</sub>@Carbon@Prussian Blue Core‚ÄďShell Nanorod Arrays for Enhanced Photoelectrochemical Performance

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    The thoughtful design of effective photoanodes has drawn significant attention. Here, a Z-scheme core‚Äďshell TiO2@carbon@prussian blue (TiO2@C@PB) is designed for photoelectrochemical water splitting. TiO2@C@PB composite film has a larger absorption range, and the band gap is decreased from 3.10 to 2.65 eV. Under illumination conditions, the TiO2@C@PB composite photoanode achieves a photocurrent density of 2.78 mA/cm2 at 1.23 V vs RHE, nearly 2.5 times higher than that of pure TiO2. The enhancement is ascribed to the suppressed recombination of photogenerated charges facilitated by the Z-scheme heterojunction and the excellent conductivity of carbon. This study offers an effective approach for developing highly efficient photoelectrochemical water-splitting photoanodes

    demo data for KK4D. KK4D: a workflow for comparative genome analysis

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    This is the genome file of Arabidopsis thaliana and rice genome IRGSP-1.0.</p

    Understanding District Heating Networks Vulnerability: A Comprehensive Analytical Approach with Controllability Consideration

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    International audienceDistrict heating networks (DHNs) are critical infrastructures that ensure production and residents' living. Analyzing vulnerability characteristics of DHNs is of great significance in heating safety decision-making. In this study, we analyze the structure, function, operation, and failure characteristics of DHNs and propose vulnerability analysis methods. We develop failure simulation models under fully-controllable (FC) and uncontrollable (UC) conditions for six failure scenarios based on component importance. To verify the proposed methods' effectiveness, we applied them to a DHN in a Chinese city. Upon analyzing the appositeness of various vulnerability assessment indicators, we find that the heat source connectivity efficiency loss rate, established based on hydraulic distribution in DHNs, can effectively characterize both topological and functional vulnerability. Our analysis also reveals that controllable DHNs, which evenly distribute heat supply among connected users for fairness, can result in lower flow and greater functional vulnerability compared to UC DHNs. In particular, under large area failure (AF) scenarios, the average functional vulnerability of UC DHNs increases by 27.59% to 38.30% compared to small-AF scenarios, while that of controllable DHNs increases by 103.78% to 120.58%. The proposed vulnerability assessment framework considering topology and function from both quantitative and qualitative perspectives, can grasp heating vulnerabilities multi-dimensional

    Extracting the speed of sound in the strongly interacting matter created in ultrarelativistic lead-lead collisions at the LHC