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Identifying changes in coal permeability with gas pressure and accurately codifying mean effective stresses in laboratory samples are crucial in predicting gas-flow behavior in coal reservoirs. Traditionally, coal permeability to gas is assessed using the steady-state method, where the equivalent gas pressure in the coal is indexed to the average of upstream and downstream pressures of the coal, while ignoring the nonlinear gas pressure gradient along the gas flow path. For the flow of a compressible gas, the traditional method consistently underestimates the length/volume-averaged pressure and overestimates mean effective stress. The higher the pressure differential within the sample, the greater the error between the true mean pressure for a compressible fluid and that assumed as the average between upstream and downstream pressures under typical reservoir conditions. A correction coefficient for the compressible fluid pressure asymptotes to approximately 1.3%, representing that the error in mean pressure and effective stress can be on the order of approximately 30%, particularly for highly pressure-sensitive permeabilities and compressibilities, further amplifying errors in evaluated reservoir properties. We utilized this volume-averaged pressure and effective stress to correct permeability and compressibility data reported in the literature. Both the corrected initial permeability and the corrected pore compressibility were found to be smaller than the uncorrected values, due to the underestimation of the true mean fluid pressure, resulting in an overestimation of reservoir permeability if not corrected. The correction coefficient for the initial permeability ranges from 0.6 to 0.1 (reservoir values are only approximately 40% to 90% of laboratory values), while the correction coefficient for pore compressibility remains at approximately 0.75 (reservoir values are only approximately 25% of laboratory value). Errors between the uncorrected and corrected parameters are quantified under various factors, such as confining pressure, gas sorption, and temperature. By analyzing the evolutions of the initial permeability and pore compressibility, the coupling mechanisms of mechanical compression, adsorption swelling, and thermal expansion on the pore structure of the coal can be interpreted. These findings can provide insights that are useful for assessing the sensitivity of coal permeability to gas pressure as truly representative of reservoir conditions. [ABSTRACT FROM AUTHOR]

Introduction: Lupus mesenteric vasculitis (LMV) is a rare but potentially life-threatening clinical entity in systemic lupus erythematosus (SLE) patients. Objective: The present study was initiated to explore the clinical features and associated factors of LMV in SLE patients. Methods: We conducted a retrospective study on 50 cases of SLE patients with lupus mesenteric vasculitis (LMV) from January 2010 to December 2019 and 89 cases of non-LMV-SLE patients with similar demographic and comorbidities were included as control. All the data regarding clinical features, laboratory findings, and treatment were reviewed independently by two experts in the field. Both univariate and multivariate logistic regression analyses were employed to identify the associated factors of LMV. Results: The incidence of LMV was 2.9% among hospitalized SLE patients in the current study. The most frequent symptom and physical sign of LMV were respectively abdominal pain (48, 96%) and abdominal tenderness (45, 90%). Through univariate and subsequent multivariate analysis, oral ulcer (OR, 4.25; P = 0.024), urinary tract involvement (OR, 5.23; P = 0.021), and elevated D-dimer (OR, 1.121; P = 0.008) were demonstrated to be positively associated with LMV, while percentage of lymphocytes (OR, 0.928; P = 0.004) and complement 3 (OR, 0.048; P = 0.008) were negatively correlated with LMV. Conclusions: Oral ulcer, urinary tract involvement, reduced percentage of lymphocytes and complement 3, elevated D-dimer could be associated factors for LMV in SLE patients. [ABSTRACT FROM AUTHOR]

This article proposes a new model for predicting sunspot activity based on the inverse number and intelligent fixed point. Firstly, in the training phase, the optimal parameters of the model are selected by the inverse-number formula and intelligent fixed-point algorithm. Secondly, in the validation phase, the model is verified by the data. Finally, the model is applied to the prediction of monthly mean sunspot number (MSN). The model's predictions are compared with those of autoregressive models (AR) and the National Oceanic and Atmospheric Administration (NOAA) predictions. The results show that the prediction accuracy of the proposed method is higher than that of previous methods. The method is then used to predict the 13-month smoothed monthly total sunspot number (MSSN13), and a higher prediction accuracy is obtained. The model proposed in this article is theoretically complete and robust. [ABSTRACT FROM AUTHOR]

An accurate measurement of force and biomechanical energy that people can impart through kicking is useful for kick-related sports training. Existing methods are indirect measurements or focus on force and not on the total energy of the kick. A kick test rig was designed, constructed and instrumented to measure the force and displacement of a vertical target subjected to kicking. The kick energy was calculated from the recorded force and displacement histories. The methodology for measurement of kick force and energy was validated by an open stance front kick test by 52 volunteers. The results showed that 67% of the participants could achieve an average energy above 100 J. An increasing trend of kick energy with increasing body weight of participant was observed. The participant’s gender had a strong influence on the kick energy, while training in martial arts does not appear to be a significant parameter. A probability analysis showed that one in one hundred adults will be able to kick with energies exceeding 215 J. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on the dynamic response of multi-ply woven fabrics subjected to impact by a spherical steel projectile in a velocity regime ranging from 120 to 200 m/s. A plain weave fabric made of Spectra 1000 fibres was used to fabricate test samples having different numbers of layers and fold patterns. The effect of fabric folding was investigated by comparing the impact performance of samples consisting of separate unfolded fabrics, continuous accordion-fold fabrics, and continuous roll-fold fabrics, respectively. It was found that the perforation resistance and energy absorption capacity were significantly improved by folding a fabric into multiple plies compared to the unfolded counterparts, and the roll-fold fabrics performed best in this study. Fabric folding seemed to have only a negligible effect on the back-face deflections of woven fabrics. The effect of thickness (or the number of layers) on energy absorption efficiency was different among the tested fabrics, due to the different inter-layer interactions depending on fold patterns. [ABSTRACT FROM AUTHOR]