Mechanism and influence factor of hydrocarbon gas diffusion in porous media with shale oil

Due to the compactness of shale reservoir matrix and the high conductivity of fractures, the hydrocarbon gas injection huff and puff method or displacement is the most realistic technology to improve shale oil recovery. The diffusion mechanism plays an important role in shale oil development; therefore, it is crucial to figure out the factors influencing diffusion, which could enhance shale oil recovery. In this paper, a physical simulation experiment is designed to evaluate the diffusion ability of  hydrocarbon gas. Diffusion experiments are conducted to simulate diffusion in the bulk fluid and in the porous media, to learn about how the pressure, permeability and fracture affect the diffusion behavior. The diffusion coefficients between the bulk diffusion and core sample diffusion are compared. The experimental results show that the diffusion coefficient and mass transfer capacity are positively correlated with permeability and pressure: increasing these parameters can promote the diffusion process. The diffusion coefficient of  hydrocarbon gas in a saturated oil core is significantly less than that in crude oil, which indicates that the porous media seriously affects the process of gas diffusion in crude oil. Fractures have little impact on the diffusion behavior. Combined with numerical simulation, the influencing factor of diffusion on the development effect of hydrocarbon gas injection is clarified. The recovery enhances and then decreases with the increasing diffusion  coefficient.Cited as: Wanyan, Z., Liu, Y., Li, Z., Zhang, C., Liu, Y., Xue, T. Mechanism and influence factor of hydrocarbon gas diffusion in porous media with shale oil. Advances in Geo-Energy Research, 2023, 7(1): 39-48. https://doi.org/10.46690/ager.2023.01.0

Effectiveness and safety of Wuling capsule for post stroke depression: A systematic review

SummaryObjectiveTo review the effectiveness and safety of Wuling capsule for post stroke depression (PSD) systematically.MethodsWe searched electronic databases for randomized controlled trials (RCTs) that compared either Wuling capsule with placebo, no treatment or Wuling capsule plus conventional treatment with conventional treatment alone in adults with post stroke depression. Relevant resources were also retrieved. Two reviewers screened the citations, assessed the risk of bias and extracted data independently.ResultsA total of 16 studies involving 1378 patients were identified for this review. There were 3 trials comparing Wuling capsule with no treatment control and 13 trials comparing Wuling capsule plus conventional treatment (Deanxit, Fluoxetine, Sertraline, Paroxetine or Citalopram) with conventional treatment alone. Meta-analyses indicated Wuling capsule used alone or integrated with conventional treatment was effective for PSD in terms of HAMD (Hamilton depression scale) scores, response rate and with less adverse effects, of which, HAMD scores decreased significantly in favor of Wuling capsule from onset time to 1 week (SMD=1.27, 95%CI: 0.71–1.83, P<0.00001), 2 weeks (SMD=1.45, 95%CI: 0.57–2.33, P=0.001), 4 weeks (SMD=2.84, 95%CI: 2.15–3.52, P<0.00001), 6 weeks (SMD=2.70, 95%CI: 2.15–3.24, P<0.00001), and 8 weeks (SMD=4.53, 95%CI: 3.55–5.50, P<0.00001) and overall effect (SMD=2.40, 95%CI: 1.75–3.05, P<0.00001) (SMD=standardized mean difference).ConclusionWuling capsule appeared to present certain antidepressant effect compared to no treatment control. With a combination of several Western medicines, Wuling capsule could be helpful in strengthening efficacy and reducing the incidence of adverse events as an alternative choice in the treatment of PSD. However, due to the limited number of included trials and relatively moderate methodological quality in the majority of studies, further large scale and rigorously designed trials are warranted to confirm the effectiveness and safety of Wuling capsule for post stroke depression

Mantle Transition Zone Discontinuities beneath the Indochina Peninsula: Implications for Slab Subduction and Mantle Upwelling

While the northward indentation of the Indian into Eurasian plates has been intensively investigated, its oblique subduction beneath the Indochina Peninsula (ICP) and the role it played on mantle structure and dynamics remain enigmatic. In this first regional-scale receiver function study of the mantle transition zone (MTZ) discontinuities beneath the ICP and its surrounding areas, we stack ~12,000 receiver functions recorded at 33 stations using a non-plane wave common-conversion-point stacking technique. Systematic spatial variations of MTZ thickness with departures between -21 and +24 km from the globally averaged value are revealed, providing independent evidence for the presence of slab segments in the MTZ beneath the central and a slab window beneath the western ICP. The results also support the existence of broad mantle upwelling adjacent to the eastern edge of the slab segments, which might be responsible for the widespread Cenozoic volcanisms and pervasively observed upper mantle low velocities in the area

Survey on Dim Small Target Detection in Clutter Background: Wavelet, Inter-Frame and Filter Based Algorithms

AbstractDim small target is an active and important research area in image processing and pattern recognition. Various algorithms have been proposed to detect and track dim small target. This paper reviews some algorithms for dim small target detection, including the wavelet based algorithms, inter-frame difference based algorithms and filter based algorithms. Also, the further development of the technologies has been briefly analyzed

TrojLLM: A Black-box Trojan Prompt Attack on Large Language Models

Large Language Models (LLMs) are progressively being utilized as machine learning services and interface tools for various applications. However, the security implications of LLMs, particularly in relation to adversarial and Trojan attacks, remain insufficiently examined. In this paper, we propose TrojLLM, an automatic and black-box framework to effectively generate universal and stealthy triggers. When these triggers are incorporated into the input data, the LLMs' outputs can be maliciously manipulated. Moreover, the framework also supports embedding Trojans within discrete prompts, enhancing the overall effectiveness and precision of the triggers' attacks. Specifically, we propose a trigger discovery algorithm for generating universal triggers for various inputs by querying victim LLM-based APIs using few-shot data samples. Furthermore, we introduce a novel progressive Trojan poisoning algorithm designed to generate poisoned prompts that retain efficacy and transferability across a diverse range of models. Our experiments and results demonstrate TrojLLM's capacity to effectively insert Trojans into text prompts in real-world black-box LLM APIs including GPT-3.5 and GPT-4, while maintaining exceptional performance on clean test sets. Our work sheds light on the potential security risks in current models and offers a potential defensive approach. The source code of TrojLLM is available at https://github.com/UCF-ML-Research/TrojLLM.Comment: Accepted by NeurIPS'2

Effects of meteorological factors on the incidence of meningococcal meningitis

Background and Objectives: Substantial climate changes have led to the emergence and re-emergence of various infectious diseases worldwide, presenting an imperative need to explore the effects of meteorological factors on serious contagious disease incidences such as that of meningococcal meningitis (MCM).Methods: The incidences of MCM and meteorology data between 1981 and 2010 were obtained from Chaoyang city. Structure Equation Modeling was used to analyze the relationships between meteorological factors and the incidence of MCM, using the LISREL software.Results: The SEM results showed that Adjusted Goodness of Fit Index (AGFI) = 0.30, Goodness of Fit Index (GFI) = 0.63, and Root Mean Square Error of Approximation (RMSEA) = 0.31. Humidity and temperature both had negative correlations with MCM incidence, with factor loads of -0.32 and -0.43, while sunshine was positively correlated with a factor load of 0.42. For specific observable variables, average air pressure, average evaporation, average air temperature, and average ground temperature exerted stronger influence, with item loads between observable variables and MCM incidence being -0.42, 0.34, -0.32, and -0.32 respectively.Conclusion: Public health institutions should pay more attention to the meteorological variables of humidity, sunshine, and temperature in prospective MCM control and prevention.Keywords: Meningococcal meningitis, Neisseria meningitidis, epidemiology, humidity, temperature, sunshine, meteorological variables, structure equation mode