Torsional Parameters Research Articles

Parametric Optimization of Torsional Parameters of Ferrocement "U" Wrapped Beams Using Recent Meta-Heuristic Optimization Algorithms.

Structural elements are subjected to different types of loads, one of which is a torsional load. Due to the complexity of the analysis, torsion was not given much importance in earlier days. With stringent updates in codal provisions and due to architectural modifications, torsion is now considered one of the major parameters for structural design. The main aim of this paper is to analyze distressed elements due to torsion. It highlights different approaches, such as destructive and non-destructive processes, to be adopted to estimate the torsional parameters of a ferrocement "U" wrapped beam. The destructive method is the experimental determination of parameters, which is absolutely necessary. The non-destructive method includes an analytical method based on a softened truss model as well as a soft computing method. The soft computing method is based on the regression coefficient analysis method along with two recent optimization algorithms, i.e., (1) ARO (artificial rabbits optimization) and (2) DAOA (dynamic arithmetic optimization algorithm). The predicted results are found to be in agreement with the experimental values (destructive method). Lastly, the obtained results from both proposed methods are analyzed, and it is found that both algorithms can be utilized in any engineering problem to determine the global optimum value with corresponding input optimal settings. As the experimental method is time-consuming and expensive, analytical, and soft computing methods can be preferred over the experimental method.

Matter-antimatter asymmetry induced by Barbero-Immirzi parameter

We review the baryon asymmetry generated in the early Universe in the framework of the metric-spinor gravity with the Holst term, which accounts for the Barbero-Immirzi parameter. For the generation of the matter-antimatter asymmetry, we have considered the model in which the time derivative of the Ricci scalar couples with matter currents (this model is known in the literature as gravitational baryogenesis). By using the current bounds on the parameter of the asymmetry, the ratio of baryon number to the entropy density, we infer a bound on the parameters characterizing the model under consideration (that is, the cosmological model in the presence of the torsion and Barbero-Immirzi parameter).

Revisiting Friedmann-like cosmology with torsion: newest constraints from high-redshift observations

As one of the possible extensions of Einstein's General Theory of Relativity, it has been recently suggested that the presence of space-time torsion could solve problems of the very early and the late-time universe undergoing accelerating phases. In this paper, we use the latest observations of high-redshift data, coming from multiple measurements of quasars and baryon acoustic oscillations, to phenomenologically constrain such cosmological model in the framework of Einstein-Cartan (EC) endowed with space-time torsion. Such newly compiled quasar datasets in the cosmological analysis is crucial to this aim, since it will extend the Hubble diagram to high-redshift range in which predictions from different cosmologies can be distinguished. Our results show that out of all the candidate models, the torsion plus cosmological constant model is strongly favoured by the current high-redshift data, where torsion would be expected to yield the late-time cosmic acceleration. Specially, in the framework of Friedmann-like cosmology with torsion, the determined Hubble constant is in very good agreement with that derived from the Planck 2018 CMB results. On the other hand, our results are compatible with zero spatial curvature and there is no significant deviation from flat spatial hypersurfaces. Finally, we check the robustness of high-redshift observations by placing constraints on the torsion parameter α, which is strongly consistent with other recent works focusing on torsion effect on the primordial helium-4 abundance.

Research on the muzzle vibration displacement test method of large-caliber rifled gun based trinocular vision

To address the problem of inaccurate muzzle vibration displacement measurements caused by the twisting of the barrel at the moment of firing of large-caliber rifled gun, a vibration displacement test method of large-caliber rifled gun based trinocular vision is proposed. A high-precision measurement system for muzzle vibration displacement based on an orthogonal imaging method with three high-speed cameras has been built. Three high-speed cameras are placed at the side and rear of the gun at orthogonal angles to each other to collect two-dimensional digital images of the gun muzzle area. Accurate displacement of the muzzle height, azimuth and recoil direction is derived by image processing techniques and multi-dimensional displacement decoupling methods. In addition, the three cameras can realize the online self-verification of parameters such as ‘recoil’ and ‘twist’. The three-dimensional vibration displacement and torsion parameters of the muzzle of a 155mm gun were obtained by a test of firing range. The test results proved the validity and accuracy of the method for the muzzle vibration displacement of rifled gun.

Progressive twist, displacement and torsional energy around pile groups

ABSTRACT The progressive twist and displacement in the sand are investigated for a set of pile groups (1,2; 1,3; 2,2) corresponding to the application of the torsional loads. A novel numerical model supported by a set of experimental observations has been considered to capture pile-soil interaction for the pile groups subjected to torsional load. The torque mobilization, progressive twist, and displacement have been computed for a range of the initial shear modulus ratio for the entire set of pile groups. As a result of twisting, the torsional energy zones are set into the soil, and there is the formation of a heave and cavity around the pile group. The torsional energy and twist rigidity parameters were evaluated for a range of shear modulus ratios of the soil. It has been observed that the torsional energy of the pile group (1,2) is significantly higher than pile groups (1,3; 2,2). A classification for torsional energy zones associated with twist rigidity and displacement rigidity factor has been suggested to set the limits for twist and displacement of the pile groups relative to a single pile. A relationship of the torsional energy with progressive twist and displacement is obtained. The components of torsional energy associated with progressive twist and displacement were obtained in the range of 0.43–0.50 and 0.50–0.57 respectively

Machinability analysis in Drilling Composites and drilling woven GFR/epoxy composites using the SPSS Method

Drilling processes in fiber-reinforced polymer composites Composite structures are essential for assembly and fabrication of parts. The economic impact of rejecting the drilled area, when reaching the assembly stage, it is important to consider the associated loss. Therefore, the motivations in drilling E-Class Fiber Reinforced Epoxy (GFRE) composites, this explains cutting conditions on torque and wear Feed, speed and pre-drill wear values. Four feeds (0.056, 0.112, 0.22, 0.315, 0.45 mm/rev) and three speeds (6.41, 12.71, 20.25, 32.03, and 50.63 m/min) and five pre-drill wear values and four artificially introduced wears) were used. Values; W = 7, 19, 26, 34 All samples are 8 mm diameter holes Drilled using a cemented carbide drill bit. Current In work, Multi-linear Regression models were used were used, Parameters of mechanical properties are related to: Thrust, torsion, peel-up, delamination, push-out delamination, Drill wear and machining parameters such as surface roughness before: feed and speed. Perforated model has high resolution; Scanning is done using flatbed color scanner, then to estimate the delamination factor, Image analysis was performed using Corel DRAW software. Multi-variable regression analysis significant coefficients of each variable, contribution is made to promotion and elimination. Laminate thickness on torque and displacement factors the results illustrate that there are significant effects. Cronbach's alpha value for the model is 0.924. Speed, Wear, Feed, Ft, T, Del.Peel, Del.Push and Ra. Results: the Cronbach's Alpha Reliability result. The overall Cronbach's Alpha value for the model is 0.924 which indicates 92% reliability. From the literature review, the above 50% Cronbach's Alpha value model can be considered for analysis

Evaluation of the left ventricular torsion and twist in patients with chronic heart failure using three dimensional speckle tracking echocardiography

Objective: To evaluate the left ventricular torsion deformation in patients with chronic heart failure using 3D speckle tracking echocardiography. Subject and method: From January 2018 to October 2020, a prospective, cross-sectional study with controls was conducted on 110 chronic heart failure patients and 50 healthy people who were treated as inpatients at the Department of Cardiology, 108 Military Central Hospital. Result: The mean age of the group of patients with heart failure was 65.82 ± 11.77, with men accounting for 66.36%, while the mean age of the control group was 65.16 ± 10.24, with men accounting for 68%. The heart failure group's left ventricular torsion parameters were all lower than the control group's: Peak-AR (4.56 ± 2.960 versus 10.41 ± 3.060; p<0.001), Peak-BR (-4.04 ± 2,250 vs -8.97 ± 2.750; p<0.001), Peak-Twist (7.94 ± 4.280 vs 18.99 ± 4.280; p<0.001), and Torsion (1.01 ± 0.560 vs 2.42 ± 0.600; p<0.001) and decreased in both the preserved EF group and the control group: Peak-AR (6.63 ± 2.49 vs 10.41 ± 3.06, p<0.05), Peak-BR (-5.02 ± 3,040 vs -8.97 ± 2.750; p<0.05), Peak-Twist (10.96 ± 4,740 vs 18.99 ± 4,280, p<0.05), Torsion (1.46 ± 0.600 vs 2.42 ± 0.600, p<0.05). The absolute value of left ventricular torsion parameters gradually decreased from heart failure with EF 50% to heart failure with a slight decrease in ejection fraction to heart failure with EF 40%. From the group of heart failure with grade I diastolic dysfunction to the group of heart failure with grade III diastolic dysfunction, the absolute value of the parameters of left ventricular torsion decreased statistically significantly. Apical rotation and left ventricular torsion have a moderate relationship with EF, left ventricular longitudinal strain as measured by 2D speckle tracking echocardiography. On 2D speckle tracking echocardiography, the angle of rotation should be weakly correlated with EF and left ventricular longitudinal strain drived from 2D speckle tracking echocardiography (2D–GLPS). Conclusion: Torsional deformation parameters of the left ventricle were lower in heart failure patients compared to controls, and they changed earlier in the group with preserved ejection fraction. Torsion deformation parameters, despite being the last variable parameter, are still quite sensitive in detecting left ventricular dysfunction.

Decoupling Planarizing and Steric Energetics to Accurately Model the Rigidity of π-Conjugated Polymers.

The π-conjugated backbone of semiconducting polymers gives rise to both their electronic properties and structural rigidity. However, current computational methods for understanding the rigidity of polymer chains fail in one crucial way. Namely, standard torsional scan (TS) methods do not satisfactorily capture the behavior of polymers exhibiting a high degree of steric hindrance. This deficiency in part stems from the method by which torsional scans decouple energy related to electron delocalization from that related to nonbonded interactions. These methods do so by applying classical corrections of the nonbonded energy to the quantum mechanical (QM) torsional profile for polymers that are highly sterically hindered. These large corrections to the energy from nonbonded interactions can substantially skew the calculated QM energies related to torsion, resulting in an inaccurate or imprecise estimation of the rigidity of a polymer. As a consequence, simulations of the morphology of a highly sterically hindered polymer using the TS method can be highly inaccurate. Here, we describe an alternative, generalizable method by which the delocalization energy can be decoupled from the energy associated with nonbonded interactions─the "isolation of delocalization energy" (DE) method. From torsional energy calculations, we find that the relative accuracy of the DE method is similar to the TS method (within 1 kJ/mol) for two model polymers (P3HT, PTB7) when compared to quantum mechanical calculations. However, the DE method significantly increased the relative accuracy for simulations of PNDI-T, a highly sterically hindered polymer (8.16 kJ/mol). Likewise, we show that comparison of the planarization energy (i.e., backbone rigidity) from torsional parameters is significantly more precise for both PTB7 and PNDI-T when using the DE method as opposed to the TS method. These differences affect the simulated morphology, with the DE method predicting a significantly more planar configuration of PNDI-T.

Contribution to the research of the possibility of application of two-parameter frequency analysis in the experimental identification of torsional vibration parameters of elastic shafts in vehicles power transmissions

During exploitation, motor vehicles are exposed to vibrational loads that lead to fatigue of users and materials of their aggregates. Therefore, vibrations must be studied even in the earliest stages of design, using mathematical models, experiments, or their combinations. In theoretical considerations, vibrations of concentrated masses are usually observed , although, with the recent development of numerical methods (especially finite element methods), attention is also being paid to vibrations of vehicle elastic systems. This usually involves idealizations, especially regarding exploitation conditions and interconnections of motor vehicle aggregates. In this paper, an attempt has been made to develop a method for identifying real vibrational loads of elastic power transmission shafts in vehicles (engine, rail, etc.) under exploitation conditions. Namely, 2D Fourier transformation was used for two-parameter frequency analysis. The possibilities of applying the procedure were illustrated on an idealized elastic torsionally loaded shaft. The conducted research showed that two-parameter frequency analysis can be used in generating torsional vibrations of elastic shafts of vehicles in laboratory conditions.

Testing dynamical torsion effects on the charged black hole’s shadow, deflection angle and greybody with M87* and Sgr. A* from EHT

Poincaré Gauge’s theory of gravity is the most noteworthy alternative extension of general relativity that has a correspondence between spin and spacetime geometry. In this paper, we use Reissner–Nordstrom–de Sitter and anti-de Sitter solutions, where torsion τ is added as an independent field, to analyze the weak deflection angles αˆ of massive and null particles in finite distance regime. We then apply αˆ to determine the Einstein ring formation in M87* and Sgr. A* and determine that relative to Earth’s location from these black holes, massive torsion effects can provide considerable deviation, while the cosmological constant’s effect remains negligible. Furthermore, we also explore how the torsion parameter affects the shadow radius perceived by both static and co-moving (with cosmic expansion) observers in a Universe dominated by dark energy, matter, and radiation. Our findings indicate that torsion and cosmological constant parameters affect the shadow radius differently between observers in static and co-moving states. We also show how the torsion parameter affects the luminosity of the photonsphere by studying the shadow with infalling accretion. The calculation of the quasinormal modes, greybody bounds, and high-energy absorption cross-section are also affected by the torsion parameter considerably.

Interobserver reliability of biplanar radiography is unaffected by clinical factors relevant to individuals at risk of pathological lower limb torsion

BackgroundAssessments of lower limb torsion are ubiquitous in clinical gait analysis practice as pathologic lower limb rotational deformity may contribute to gait abnormalities, anterior knee pain, as well as other debilitating conditions. Understandably, the overall utility of any torsional assessment is dependent on the measurement method’s intrinsic accuracy, precision, and robustness to clinical interference factors. Recently, biplanar radiography (BPR) measurements of torsion have been shown to be both accurate and precise, but the robustness of BPR to potential interference factors is unknown. Research questionHow robust are BPR lower limb torsional assessments to six potential interference factors: amount of torsion, skeletal maturity, radiograph quality, prior osteotomy, presence of implants, and observer training background and experience? MethodsIn this retrospective cohort study, four observers of diverse backgrounds and experience generated digital 3D reconstructions of 44 lower limbs using BPR images obtained during standard of care visits (age range 7–35 years). From each reconstruction, four lower limb torsional parameters were computed: femoral torsion, femorotibial rotation, tibial torsion, and transmalleolar axis equivalent. The mean absolute deviation (MAD) of each torsional parameter – calculated across the four observers – was used as the measure of reliability and tested against all interference factors. ResultsResults demonstrated that the average MAD was 2.1 degrees for femoral torsion, 3.0 degrees for transmalleolar axis equivalent, 3.8 degrees for femorotibial rotation, and 4.7 degrees for tibial torsion. None of the six potential interference factors were found to systematically influence BPR reliability across all four torsional parameters. Of the factors found to statistically influence one or more torsional parameter, none affected MAD values to a clinically meaningful extent. SignificanceIn addition to being accurate and precise, BPR appears to be robust to several clinical factors relevant to children and young adults with or at risk for pathological lower limb torsion.

Evaluation of subclinical left ventricular systolic dysfunction using two-dimensional speckle-tracking echocardiography in patients with Child-Pugh A and B cirrhosis: A case-control study.

Although studies have proven that liver cirrhosis affects cardiac hemodynamics by means of circulatory overload, they present with definite cardiac functional alteration mostly with end-stage disease. There is limited data on relationship betweenprogression of cirrhosis, cardiac mechanics and sub-clinical dysfunction. This study was done to assess ventricular myocardial mechanics using speckle tracking and deformation imaging among Child-Turcotte-Pugh (CTP) classification A and B cirrhosis. Seventy patients with cirrhosis of Child-Pugh A/B class and sixty-two healthy subjects were prospectively evaluated by standard conventional echocardiography and deformation imaging with rotational echocardiography. Clinical stage of liver cirrhosis was assessed by model for end-stage liver disease (MELD) scores and CTP classification. Mean ages of patients with cirrhosis and controls were 55.64±14 years and 52.24±12 years, respectively. Though left ventricular (LV) dimensions (end diastolic dimension: 47.27±4.6 mm vs. 45.03±3.8 mm, p = 0.003; end systolic dimension: 30.33±4.9 mm vs. 28.40±2.91mm, p = 0.006) and volumes (end diastolic volume: 82.08±22.53 mL vs. 68.18±15.75 mL, p = 0.001; end systolic volume: 28.60±8.42 mL vs. 22.18±7.48 mL, p = 0.001) were significantly higher in patients with cirrhosis, mean ejection fraction (EF) by Simpsons method was higher among controls (65.83±5.79% vs. 68.35±5.79%, p = 0.009). Left atrial volume was higher in cirrhosis group indicating presence of diastolic dysfunction (41.24±14.10 mL vs. 26.08±6.4 mL, p = 0.001). Global longitudinal strain as assessed by speckle tracking echocardiography did not show statistical significant difference between two groups (-22.35±4.08% vs. -21.80±2.54%, p = 0.348). Median value of torsion parameters in patients with cirrhosis did not differ compared to controls (torsion in degrees: 2.46 vs. 2.79, p = 0.268). Patients with Child-Pugh A and B stages of cirrhosis present with preserved longitudinal strain, normal torsion but with subtle diastolic dysfunction. Higher MELD score may correlate with increased longitudinal strain possibly due to hyperdynamic state.

Open Force Field BespokeFit: Automating Bespoke Torsion Parametrization at Scale.

The development of accurate transferable force fields is key to realizing the full potential of atomistic modeling in the study of biological processes such as protein-ligand binding for drug discovery. State-of-the-art transferable force fields, such as those produced by the Open Force Field Initiative, use modern software engineering and automation techniques to yield accuracy improvements. However, force field torsion parameters, which must account for many stereoelectronic and steric effects, are considered to be less transferable than other force field parameters and are therefore often targets for bespoke parametrization. Here, we present the Open Force Field QCSubmit and BespokeFit software packages that, when combined, facilitate the fitting of torsion parameters to quantum mechanical reference data at scale. We demonstrate the use of QCSubmit for simplifying the process of creating and archiving large numbers of quantum chemical calculations, by generating a dataset of 671 torsion scans for druglike fragments. We use BespokeFit to derive individual torsion parameters for each of these molecules, thereby reducing the root-mean-square error in the potential energy surface from 1.1 kcal/mol, using the original transferable force field, to 0.4 kcal/mol using the bespoke version. Furthermore, we employ the bespoke force fields to compute the relative binding free energies of a congeneric series of inhibitors of the TYK2 protein, and demonstrate further improvements in accuracy, compared to the base force field (MUE reduced from 0.560.390.77 to 0.420.280.59 kcal/mol and R2 correlation improved from 0.720.350.87 to 0.930.840.97).

Transfer Matrix Method for Calculating the Transverse Load Distribution of Articulated Slab Bridges

Articulated slab bridges have been widely used by transportation administration for short-to-medium span bridges because of their good economy, convenient construction, and environmental advantages, while the presence of shear keys increases the complexity of structural behavior. Developing more reasonable analysis approaches of quick assessment, pre-design, and hand calculations for the articulated slab bridges is a challenge because of the peculiar shear key mechanism. This paper is devoted to presenting a recursive algorithm, based on the force equilibrium conditions of each individual slab, thus resulting in simultaneous equations of the transfer matrix method (TMM). In this procedure, the state vector is an array composed of vertical displacement, shear force, unit constant; and the transfer matrix contains the bending and torsional stiffness parameters of simply supported slabs. Then, the influence line of transverse load distribution (TLD) is calculated for each slab by introducing boundary conditions. To validate and verify the efficiency of the TMM algorithm, a transversely prefabricated void slab bridge with a span of 20 m is considered as a case study. The traditional force (FM) and finite element (FEM) methods are used for comparison and validation. It is demonstrated that the TMM can provide good results with higher algorithm efficiency by exempting the modeling tasks in FM and FEM and capture variations in TLD along the bridge’s span. In addition, the influence of the span length and relative stiffness coefficient of slabs on the TLD of articulated slab bridges are analyzed from the parametric analysis.

Supporting information for: Open Force Field BespokeFit: Automating Bespoke Torsion Parametrization At Scale

Supporting information for: Open Force Field BespokeFit: Automating Bespoke Torsion Parametrization At Scale

Effect of Drill Attrition on Machinability in Drilling Woven GFR Epoxy Composites

Drilling processes in fiber-reinforced polymer composites Composite structures are essential for assembly and fabrication of parts. The economic impact of rejecting the drilled area, when reaching the assembly stage It is important to consider the associated loss. Therefore, the motivations in drilling E-Class Fiber Reinforced Epoxy (GFRE) composites, this explains cutting conditions on torque and wear Feed, speed and pre-drill wear values. Four feeds (0.056, 0.112, 0.22, 0.315, 0.45 mm/rev) and three speeds (6.41, 12.71, 20.25, 32.03, and 50.63 m/min) and five pre-drill wear values and Four artificially introduced wears) were used. Values; W = 7, 19, 26, 34 All samples are 8 mm diameter holes Drilled using a cemented carbide drill bit. Current In work, Multi-linear Regression models were used were used, Parameters of mechanical properties are related to: Thrust, torsion, peel-up, delamination, push-out delamination, Drill wear and machining parameters such as surface roughness before: feed and speed. Perforated model has high resolution; Scanning is done using flatbed color scanner, then to estimate the delamination factor, Image analysis was performed using Corel DRAW software. Multi-variable regression analysis significant coefficients of each variable, contribution is made to promotion and elimination. Laminate thickness on torque and displacement factor the results illustrate that there are significant effects. Cronbach's alpha value for the model is 0.924.

The torsional nonlinear-elastic parameter βG for uniaxial stress monitoring of concrete specimens

Nonlinear elastic characterization of concrete materials is a promising approach for actual stress detection in structural elements. In this study we investigate the use of the “torsional nonlinear parameter” βG of elongated concrete specimens to detect the actual uniaxial stress level. We derive a theoretical expression of βG ex-pressed in terms of the third order elastic constants l, m and n. Then we apply quasistatic uniaxial loading cycles on a 15 x 15 x 60 cm3 specimen and measure βG using the torsional resonance technique, obtaining an average βG = -125. This re-sult is compared against the βG measured using ultrasonic wave propagation in the same specimen during the same test. Finally, we measure βG in a real size reinforced concrete column using the torsional resonance technique, obtaining βG =-650. A final discussion is posed to analyze the findings and to guide future research.

Exact Matrix Stiffness Method for Out-of-Plane Buckling Analysis of Funicular Arches Considering Warping Deformations

The out-of-plane buckling behavior of arches is closely related to the element torsional behavior. The traditional 12-degree-of-freedom second-order element stiffness matrix which uses a simplified element torsional stiffness GJ/[Formula: see text] (where [Formula: see text] is the shear modulus, [Formula: see text] the St. Venant torsion constant, [Formula: see text] the element length) may significantly underestimate the out-of-plane buckling loads of funicular arches. This paper presents a simple and effective exact matrix stiffness method (MSM) for the out-of-plane buckling analysis of funicular arches. The developed MSM uses a 14-degree-of-freedom second-order element stiffness matrix of three-dimensional beam-columns considering both torsion and warping deformations. The out-of-plane buckling analysis of funicular arches is performed by using the global structural stability stiffness matrix, which combines the transformed second-order element stiffness matrices. The proposed MSM with the exact 14-degree-of-freedom second-order element stiffness matrix for the out-of-plane buckling analysis is verified by comparing with some classical solutions of funicular circular and parabolic arches with box sections and I-sections. Further discussions show that the 14-degree-of-freedom second-order element stiffness matrix may be reduced to a simplified 12-degree-of-freedom form only by deriving the exact element torsional stiffnesses, which could be significantly larger than GJ/[Formula: see text] for members with large cross-sectional torsional stiffness parameters (especially open cross-sections).

Axial-torsional mode correlation analysis of a drill string system with non-smooth characteristics

Axial-torsional coupling vibrations are dangerous and complex vibrations that can cause abnormal working conditions in the drilling system. Therefore, the vibration mode correlation is essential in the dynamic analysis of the response complexity of the system to reduce the vibration risk level. In this paper, an axial-torsional lumped parameter model with 5-DOF (degrees of freedom) is proposed to investigate the axial-torsional mode correlation of a drill string system with non-smooth characteristics. Numerical simulations are carried out by using the 4th-5th order Runge-Kutta method with adaptive time steps, and the simulation results are compared and verified by the 5-DOF torsional lumped parameters model and field measurement data. It also performs time domain, frequency domain, and correlation coefficient analysis. The results reveal the mode shape and correlations of an axial-torsional mode in coupled vibrations with and without a bit-bounce. Bit-bounce and stick-slip coupling vibration can be produced by increasing the rotary table speed. The torsional angular velocity of the proposed model is smaller than that of the comparative model, which is in good agreement with the field data.

Refinement of the Optimized Potentials for Liquid Simulations Force Field for Thermodynamics and Dynamics of Liquid Alkanes.

Torsion and Lennard-Jones parameters of the optimized potentials for liquid simulations (OPLS) all-atom force field have been refined for describing thermodynamics and dynamics of a wide range of liquid alkanes. Monte Carlo statistical mechanics (MC) and molecular dynamics (MD) simulations were carried out. For thermodynamics properties, MC simulations with truncated electrostatic interactions performed very closely to MD simulations with a Verlet neighbor list and the particle mesh Ewald algorithm. The average errors in comparison with experimental data for computed properties were improved with the modified force field (OPLS/2020), especially for long-chain alkanes. For liquid densities, heats of vaporization, and free energies of hydration, the average errors are 0.01 g/cm3, 0.2 kcal/mol, and ca. 0.5 kcal/mol, respectively; significant gains were made for relative heats of vaporization of isomeric series. Results for self-diffusion coefficients also reproduce experimental data well for linear alkane liquids up to hexadecane. The new force field is suitable for use in improved modeling of myriad systems of importance in chemistry, biology, and materials science.