A COMPARISON BETWEEN THE PERTURBED-CHAIN STATISTICAL ASSOCIATING FLUID THEORY EQUATION OF STATE AND MACHINE LEARNING MODELING APPROACHES IN ASPHALTENE ONSET PRESSURE AND BUBBLE POINT PRESSURE PREDICTION DURING GAS INJECTION

Predicting asphaltene onset pressure (AOP) and bubble point pressure (Pb) is essential for optimization of gas injection for enhanced oil recovery. Pressure-Volume-Temperature or PVT studies along with equations of state (EoSs) are widely used to predict AOP and Pb. However, PVT experiments are costly and time-consuming. The perturbed-chain statistical associating fluid theory or PC-SAFT is a sophisticated EoS used for prediction of the AOP and Pb. However, this method is computationally complex and has high data requirements. Hence, developing precise and reliable smart models for prediction of the AOP and Pb is inevitable. In this paper, we used machine learning (ML) methods to develop predictive tools for the estimation of the AOP and Pb using experimental data (AOP data set: 170 samples; Pb data set: 146 samples). Extra trees (ET), support vector machine (SVM), decision tree, and k-nearest neighbors ML methods were used. Reservoir temperature, reservoir pressure, SARA fraction, API gravity, gas−oil ratio, fluid molecular weight, monophasic composition, and composition of gas injection are considered as input data. The ET (R2: 0.793, RMSE: 7.5) and the SVM models (R2: 0.988, RMSE: 0.76) attained more reliable results for estimation of the AOP and Pb, respectively. Generally, the accuracy of the PC-SAFT model is higher than that of the AI/ML models. However, our results confirm that the AI/ML approach is an acceptable alternative for the PC-SAFT model when we face lack of data and/or complex mathematical equations. The developed smart models are accurate and fast and produce reliable results with lower data requirements

Comparison of anxiety and depression symptoms between male daily smokers and nondaily smokers resident in Kashan city during 2016-2017

Background: Several studies have shown the dangers of cigarette smoking among daily smokers. However, another group that has recently been investigated is a nondaily smoking group. The nondaily smokers experience the adverse health effects of smoking more than nonsmokers. This study aimed to evaluate the prevalence of depression and anxiety among daily and nondaily smokers. Materials and Methods: In this cross-sectional study with snowball sampling, 385 male residents of Kashan were selected and divided into three groups of daily smokers (118), nondaily smokers (114) and nonsmokers (135). Depression and anxiety were measured by the Beck depression inventory and beck anxiety inventory. Results: The results of the current study showed no significant difference in the prevalence of depression and anxiety in both daily and nondaily smokers (P<0.05). Also, depression and anxiety levels in daily smokers and nondaily smokers were significantly higher than nonsmokers (P<0.05). Conclusion: The prevalence of depression and anxiety among nondaily smokers is the same as the daily smokers. Thus, in both groups, in addition to smoking, special attention should be paid to anxiety and depression disorders

Time-dependent hygro-thermal creep analysis of pressurized FGM rotating thick cylindrical shells subjected to uniform magnetic field

Time-dependent creep analysis is presented for the calculation of stresses and displacements of axisymmetric thick-walled cylindrical pressure vessels made of functionally graded material (FGM). For the purpose of time-dependent stress analysis in an FGM pressure vessel, material creep behavior and the solutions of the stresses at a time equal to zero (i.e. the initial stress state) are needed. This corresponds to the solution of the problem considering linear elastic behavior of the material. Therefore, using equations of equilibrium, stress-strain and strain-displacement, a differential equation for displacement is obtained and subsequently the initial elastic stresses at a time equal to zero are calculated. Assuming that the Magneto-hygro-thermoelastic creep response of the material is governed by Norton's law, using the rate form of constitutive differential equation, the displacement rate is obtained and then the stress rates are calculated. Once the stress rates are known, the stresses at any time are calculated iteratively. The analytical solution is obtained for the plane strain condition. The pressure, inner radius and outer radius are considered to be constant and the magnetic field is uniform. Material properties are considered as power law function of the radius of the cylinder and the poisson's ratio as constant. Following this, profiles are plotted for different values of material exponent for the radial, circumferential and effective stresses as a function of radial direction and time. The in-homogeneity exponent have significant influence on the distributions of the creep stresses

Comparison of the effects of transcranial direct current stimulation and mindfulness-based stress reduction on mental fatigue, quality of life and aggression in mild traumatic brain injury patients: a randomized clinical trial

Abstract Background The rate of traumatic brain injuries (TBIs) due to the accidents is high around the world. Patients with mild TBIs may suffer from some psychological disorders, including aggression, and mental fatigue, and thus their quality of life decreased. Among different treatments for TBI, two treatments, namely transcranial direct current stimulation (tDCS), and mindfulness-based stress reduction (MBSR) have shown to be effective. Therefore, this study aimed to compare the effects of these two treatments on mental fatigue, aggression and quality of life in mTBI patients. Materials and methods This randomized controlled trial study was conducted on 48 TBI patients referred to emergency and neurosurgery departments of Shahid Beheshti Hospital, Kashan, Iran. They were selected using the convenience sampling method. Data were collected using the mental fatigue scale, the World Health Organization Quality of Life-BREF (short version), and the Buss–Perry Aggression Questionnaires. Then, the data were analyzed using a Mixed Repeated Measures ANOVAs, and the Levene and Kolmogorov–Smirnov tests by SPSS-23 software. Results The mean age of patients in the three groups of MBSR, tDCS and control were 69.38 + 6.11 (25% male), 25.40 + 12.11 (25% male) and 69.37 + 0.2 (18.8% male), respectively. There was no significant difference between the three groups in terms of mental fatigue, quality of life and aggression (P < 0.05). In addition, the results showed that there was a significant difference between the main effect of time and the interaction between time and group (P < 0.001). Conclusions Both MBSR and tDCS methods are effective in reducing the mental fatigue and aggression and increasing quality of life of mTBI patients; MBSR treatment, as indicated in the present study, can be more effective than tDCS in patients with mTBI. Trial registration : Thailand Registry of Clinical Trials, TCTR20180827003 Registered on August 24, 2018