Torsional Analysis Research Articles

Right Ventricular Segmental Rotation and Torsion in Normal Subjects on 2D Speckle Tracking Echocardiography

Background/Aims: Little is known about the complex anatomy of right ventricular (RV) torsion in the general population. This study was designed to assess RV’s global and segmental torsional motion in subjects without cardiac pathologies.Methods: We used the Vivid 7 ultrasound system (GE Healthcare, Chicago, IL, USA) to acquire parasternal short-axis views of the RV at the basal and apical levels, and analyzed global and segmental torsion using a 2D speckle tracking algorithm in EchoPAC workstation (GE Healthcare, Wauwatosa, WI, USA).Results: Forty-eight individuals (44 ± 17 years, 54% male) were included, with either normal left ventricular diastolic function (group I, n = 40) or grade I diastolic dysfunction (group II, n = 8). Group I showed global peak systolic torsion of 9.0 ± 6.6 degrees with higher segmental torsion in the mid-interventricular septum (IVS) than in the anterior walls (<i>p</i> = 0.001). Global RV torsion showed a very strong positive correlation with apical rotation (r = 0.91, <i>p</i> < 0.001). Group I exhibited higher segmental torsion in the anterior-IVS and mid-IVS walls than group II (9.8 ± 7.1 vs. 3.5 ± 9.6 degrees, <i>p</i> = 0.036; 10.4 ± 9.1 vs. 2.4 ± 12.3 degrees, <i>p</i> = 0.038, respectively).Conclusions: Analysis of RV segmental torsion was feasible using a 2D speckle tracking algorithm. Apical rotation can be used as a simplified index of global RV torsion. Further studies are needed to evaluate the clinical impact of RV torsion in various pathologies.

Axial orientation of the femoral trochlea is superior to femoral anteversion for predicting patellar instability.

The femoral anteversion angle is considered to be the same as femoral torsion; however, the femoral anteversion angle is strongly influenced by the femoral posterior condylar morphology. It remains unclear whether the femoral anteversion angle and axial orientation of the femoral trochlea can predict patellar instability. This study aimed to redefine the femoral inherent torsion, verify whether the femoral anteversion angle reflects the femoral inherent torsion, and compare the validity and calculate the cut-off values of the femoral anteversion angle and femoral trochlear axial orientation for predicting patellar instability. Seventy-three patients with patellar instability and 73 matched controls underwent computed tomography to measure the femoral anteversion angle, femoral inherent torsion, and femoral trochlear axial orientation. Pearson's product moment correlation coefficients and linear regression were calculated to determine correlations between measurements. Receiver operating characteristic curves and nomograms were plotted to evaluate the predictive validity of the femoral anteversion angle and femoral trochlear axial orientation for patellar instability. All measurements showed excellent intra- and inter-observer reliability. Compared with the control group, the patellar instability group had a significantly larger femoral anteversion angle (25.4 ± 6.4° vs. 20.2 ± 4.5°) and femoral inherent torsion (18.3 ± 6.7° vs. 15.8 ± 3.4°), and significantly smaller femoral trochlear axial orientation (58.1 ± 7.3° vs. 66.9 ± 5.1°). The femoral anteversion angle and femoral trochlear axial orientation had area under the receiver operating characteristic curve values of 79 and 84%, respectively, and cut-off values of 24.5° and 62.7°, respectively. The calibration curve and decision curve analysis showed that the femoral trochlear axial orientation performed better than the femoral anteversion angle in predicting patellar instability. There was a strong correlation between the femoral anteversion angle and femoral inherent torsion (r > 0.8). Linear regression analysis of the femoral inherent torsion with the femoral anteversion angle as the prediction variate showed moderate goodness-of-fit (adjusted R2 = 0.69). The femoral anteversion angle moderately reflects the femoral inherent torsion. The femoral trochlear axial orientation is better than the femoral anteversion in predicting patellar instability in terms of predictive efficiency, consistency with reality, and net clinical benefit. These findings warn orthopaedists against overstating the role of the femoral anteversion angle in patellar instability, and suggest that the femoral trochlear axial orientation could aid in identifying at-risk patients and developing surgical strategies for patellar instability. III.

Application of generalized finite difference method for elastoplastic torsion analysis of prismatic bars

In this paper, the generalized finite difference method (GFDM) is employed for the elastic-plastic torsion analysis of prismatic bars, and the generalized finite difference numerical scheme of the elastic-plastic torsion governing equation is derived. This approach divides the computational domain into a series of overlapping sub-domains and constructs a system of linear equations based on Taylor series expansion and moving least squares. With the help of Picard's iterative method, the elastic solution is utilized as the initial guess to reach the elastic-plastic solution. The plastic nonhomogeneous term is then evaluated via radial basis function (RBF) interpolation. Since the generalized finite difference method does not require intra-domain integration and allows random distribution of nodes, it could simply deal with complex computational domain problems. In numerical experiments, the elastic-plastic torsion examples of square-section bars and linear guide rail reveal that the numerically developed generalized finite difference model is a reliable and effective analysis solution for elastic-plastic torsion problems of prismatic bars.

Molecular Dynamics Simulation of Ligands from Anredera cordifolia (Binahong) to the Main Protease (M pro) of SARS-CoV-2.

COVID-19 in Indonesia is considered to be entering the endemic phase, and the population is expected to live side by side with the SARS-CoV 2 viruses and their variants. In this study, procyanidin, oleic acid, methyl linoleic acid, and vitexin, four compounds from binahong leaves-tropical/subtropical plant, were examined for their interactions with the major protease (Mpro) of the SARS-CoV 2 virus. Molecular dynamics simulation shows that procyanidin and vitexin have the best docking scores of -9.132 and -8.433, respectively. Molecular dynamics simulation also shows that procyanidin and vitexin have the best Root Mean Square Displacement (RMSD) and Root Mean Square Fluctuation (RMSF) performance due to dominant hydrogen, hydrophobic, and water bridge interactions. However, further strain energy calculation obtained from ligand torsion analyses, procyanidin and vitexin do not conform as much as quercetin as ligand control even though these two ligands have good performance in terms of interaction with the target protein.

Application of the Principal Components Analysis to Optical Fiber Sensor for Multiparametric Detection of Strain and Torsion

In this article, a multiparameter detection method for torsion and strain based on a single optical fiber sensor (OFS) is demonstrated combined with principal components analysis (PCA). A helical intermediate-period fiber grating (HIPFG) is used to measure the strain (0–1600 μϵ) and torsion (0–±360°) simultaneously. The wavelengthshift of the HIPFG shows a linear relationship with strain with the sensitivity of −1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> nm/μϵ, but an ambiguous relationship with torsion change. Hence, PCA is coupled to the experimental data to improve the sensing performance and the first principal component (PC1) and second principal component (PC2) are obtained. Based on PC1, the strain sensitivity and torsion sensitivity are calculated to be −0.37 μϵ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> and 9050.74 (rad/mm) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> . Intriguingly, multiparameter analysis for strain and torsion is obtained with the PC1 and PC2 and the simultaneous prediction of strain and torsion is succeeded. The prediction error for strain and torsion are 7.6% and 3.5%, respectively, emphasizing the link between principal components and target parameters. The method proposed provides a new entry to multiparameter sensing and analysis.

Nonlinear torsional vibration analysis of shearer semi-direct drive cutting transmission system subjected to multi-frequency load excitation

Nonlinear torsional vibration analysis of shearer semi-direct drive cutting transmission system subjected to multi-frequency load excitation

Torsional Stress Analysis of Improved Composite Box Girder with Corrugated Steel Webs

Based on Umansky’s second theory, this paper studies the torsional stress of an improved composite box girder with corrugated steel webs and considers the effective elastic modulus of the converted section. The calculation formulas of the torsional stress of a single-box multi-cell-improved composite box girder with corrugated steel webs were derived, the initial parameter solution of the generalized displacement and internal force under the restrained torsion were obtained through a model test and finite element simulation, the correctness of the theoretical formulas were verified, the distribution forms of the torsional stress on the box girder section were analyzed, and the effects of the height/width ratio, the width ratio of the cantilever plate, and the thickness of the bottom steel flange on the torsional stress were studied. The results show that the theoretical values and finite element values are in good agreement with the measured values for the torsional stress at each measuring point, and the errors are within 10%. The torsional normal stress of the bottom steel flange of the box girder is much greater than that of the top concrete flange, and the corrugated steel web hardly bears the torsional normal stress. The total shear stress of the box girder is mainly borne by the corrugated steel web on both sides and the bottom steel flange and less by the top concrete flange. The greater height/width ratio, the greater the difference between the torsional normal stress of the bottom steel flange and the top concrete flange. For a box girder with small height/width ratio, the total shear stress of each plate is significantly greater than that of a box girder with large height/width ratio.

The strain gradient-based torsional vibration analysis of micro-rotors with nonlinear flexural-torsional coupling

The powerful non-classical continuum theory of strain gradient elasticity is capable of effectively capturing small-scale effects in micro-structures. Based on this theory, a formulation is developed to investigate the coupled torsional-flexural vibrations of micro-rotors in the presence of inertia nonlinearities arising from the eccentricity and gyroscopic motion of the rotors. With the aid of a weighted-residual technique, coupled nonlinear partial differential equations of motion are truncated into a discrete model. Then, the resonance of the fundamental mode of the torsional vibration excited by the flexural vibration is investigated by utilizing the perturbation method of multiple scales. Moreover, a numerical simulation approach is conducted to confirm the validity of the analytical solution proposed by the multiple scales perturbation method. Obtained results for the resonant frequency and amplitude of the fundamental torsional mode indicate that the strain gradient theory can predict far more reliable results than the classical continuum mechanics for micro-rotors with very thin shafts.

Robust algorithm of indirect tyre pressure monitoring system based on tyre torsional resonance frequency analysis

• Detects changes in tyre pressure by monitoring changes in tyre resonance frequency. • Eliminating the disturbances of engine and driveline on frequency estimation. • Key parameters for evaluating tyre torsional vibration characteristics is proposed. • Methods proposed to compensate for the effects of road roughness and ambient temperature. • The proposed algorithm improves the robustness of frequency estimation. This paper focuses on an indirect Tyre Pressure Monitoring System (TPMS) algorithm based on frequency analysis of tyre torsional vibration. Tyre vibration is analysed using a tyre structure model, and the tyre resonance frequency is estimated using an Autoregressive (AR) model. The vibration disturbances from the engine and driveline that affect the estimation of the tyre torsional frequency are analysed, and a notch filter is designed to eliminate the disturbances. The torsional vibration of the driveline is identified by the correlation analysis of driving wheel speed. Two qualitative evaluation indexes of tyre torsional vibration characteristics are proposed. The corresponding quantitative parameters are used to determine the tyre torsional vibration state to eliminate the interference of undesirable vibration states on the frequency calculation. A road roughness estimation method is proposed based on tyre vertical vibration information in the wheel speed. The estimated road roughness parameters compensate for the calculated resonance frequency affected by road roughness. Based on the relationship between measured resonance frequency and temperature under a constant tyre pressure condition, the frequency variation value affected by tyre rubber stiffness variation due to temperature variation is calculated using the ambient temperature signal. The calculated resonance frequency is corrected to eliminate the coupling effect of gas stiffness and rubber stiffness, the impact of temperature variation on tyre pressure estimation is compensated. The results of vehicle road tests demonstrate the robustness of the proposed tyre pressure monitoring algorithm.

High-order torsion analysis of sandwich beams of rectangular cross-section

The structural response of soft-core sandwich beams of rectangular cross-section subjected to torsion is investigated. The paper uses the concepts of the extended high-order sandwich panel theory and generalizes the approach to account for the torsional response and its unique mechanisms. An analytical model that utilizes this generalized approach is formulated. The results of the model are presented and compared with the results of a reference model and a finite element analysis. Emphasis is placed on the torsional resistance mechanisms, their interaction, and the torsional-related localized effects. The results of the present model are in good agreement with the finite element analysis in terms of displacements and stresses, including the localized effects attributed to the soft-core. It is also shown that the present model can identify and quantify the localized effects while reference models available in the literature fail to do so. The results of the model contribute to the understanding of the torsional response of soft-core sandwich beams, including the transition between the warping and Saint-Venant torsional mechanisms and the localized effects associated with the soft-core and the application of boundary conditions to the different layers.

Free Torsional Vibration Analysis of Nanorods with Non-circular Cross-Sections Based on the Second-Order Strain Gradient Theory

Free Torsional Vibration Analysis of Nanorods with Non-circular Cross-Sections Based on the Second-Order Strain Gradient Theory

Impact of different characteristics of the ice–propeller interaction torque on the torsional vibration response of a Polar-Class shaftline

During navigation in Polar regions, ice-induced torque excitation endangers the operation and integrity of ship propulsion systems. Predicting these dynamic phenomena through proper numerical models is therefore essential. This paper studies the influence of different properties of the ice–propeller torque on the transient torsional dynamics of a Polar-Class shafting system. We initially considered the ice torque defined by the current regulatory framework. Hence, we examined variants of four ice impact properties—(i) rise shape; (ii) angular span; (iii) ramps up–down feature; (iv) number of ice impacts—to study the transient and steady-state conditions induced by the ice–propeller excitation. We performed a series of torsional vibration analyses using the numerical model of the shaftline of the Canadian Coast Guard (CCG) icebreaker Terry Fox. Furthermore, we tested the system with Diesel engine and electric motor excitation models interchangeably; the electric drive solution proved to counter ice-induced transient perturbations more effectively. The results indicate that the ice impact span, the ramps up–down application, and the number of impacts are the most important factors to affect the shaftline’s rotational speed drop and response torque. In particular, the significance of the ice impact ramps is such that it might entail a review of the in-force regulatory guidelines.

Semi-active control of crankshaft skyhook based on magnetorheological torsional damper

The purpose of this study was to solve the problem that the damping of rubber or silicone oil torsional dampers used in crankshafts is not adjustable and cannot effectively control torsional vibration at different resonant frequencies. Based on the controlled rheological properties of magnetorheological (MR) smart materials, this study designed a new type of variable damping MR torsional damper (MRTD) and proposed a semi-active control method to effectively control the torsional vibration of the crankshaft under multiple harmonic resonances. First, a mechanical model of the MRTD and a lumped parametric mass model of the crankshaft system were developed, and the resonance frequency harmonic range of the crankshaft system operation was determined by the torsional vibration characteristics analysis. Then a semi-active skyhook control method for the MRTD was proposed, and a joint control simulation analysis was performed using Amesim and Matlab software. The torsional vibration control effects of the crankshaft system with no damper, MRTD with different damping coefficients, and MRTD with skyhook control under acceleration and uniform speed conditions were comprehensively investigated. The simulation results indicated that the skyhook damping control significantly reduced the torsional vibration amplitude under both acceleration and uniform speed conditions, verifying the effectiveness of the skyhook-based control strategy for MRTD.

Elastic Lateral‐Torsional Buckling of Girders with Corrugated Web: Equivalent Section Properties Approach

AbstractOne of the benefits of using corrugated web girders is the increase of lateral‐torsional buckling resistance. Different approaches have been presented to obtain the value of the critical moment as a function of the cross‐section geometry. Previous research works consider that the increase in buckling resistance must be accredited to a higher warping constant. The paper presents a systematic finite element numerical analysis of girders with different corrugated web shapes. Bending with respect to the weak axis shows that corrugated web implies higher moment of inertia. Torsion analysis results clearly demonstrate that the increase of torsion resistance is mainly due to higher torsional constant. The paper compares the elastic critical moment values obtained by using finite element elastic buckling analysis with the values provided by theoretical expressions introducing equivalent section properties. Results show that the equivalent section properties approach provides values very close to those obtained using finite elements. Finally, the paper presents closed form expressions to directly compute approximate equivalent section properties of any girder with corrugated web, which compare very satisfactory with those values obtained with finite element buckling analysis.

Machine learning shows torsion angle preferences in left-handed and right-handed quadruplex DNAs

Left-handed G quadruplexes (LHG4) have been recently discovered as a new class of G quadruplexes. The biological functions of LHG4s are still unknown, but they share a striking resemblance to Z-DNA in their helicity and jagged phosphate backbone. To further understand structural features of the LHG4s that define their left handedness, we have employed human-interpretable machine-learning methods to classify right- and left-handed G4s purely based on torsional angle analysis. Our results reveal the importance of the α, β, δ, and χ angles in left-handed structuring across both Z-DNAs and LHG4s. Our analysis may serve as the first step to understanding the conditions of formation for LHG4s and their potential biological relevance.

Exercise-induced myocardial edema in master triathletes: Insights from cardiovascular magnetic resonance imaging

BackgroundStrenuous exercise has been associated with functional and structural cardiac changes due to local and systemic inflammatory responses, reflecting oxidative, metabolic, hormonal, and thermal stress, even in healthy individuals. We aimed to assess changes in myocardial structure and function using cardiovascular magnetic resonance (CMR) imaging in master triathletes early after a full-distance Ironman Triathlon race.Materials and methodsTen master triathletes (age 45 ± 8 years) underwent CMR within 3 h after a full-distance Ironman Triathlon race (3.8 km swimming, 180 km cycling, and 42.2 km running) completed with a mean time of 12 ± 1 h. All the triathletes had a 30-day follow-up CMR. Cine balanced steady-state free precession, T2-short tau inversion recovery (STIR), tagging, and late gadolinium enhancement (LGE) imaging sequences were performed on a 1.5-T MR scanner. Myocardial edema was defined as a region with increased T2 signal intensity (SI) of at least two SDs above the mean of the normal myocardium. The extent of myocardial edema was expressed as the percentage of left ventricular (LV) mass. Analysis of LV strain and torsion by tissue tagging included the assessment of radial, longitudinal, and circumferential peak systolic strain, rotation, and twist.ResultsCompared with postrace, biventricular volumes, ejection fraction, and LV mass index remained unchanged at 30-day follow-up. Global T2 SI was significantly higher in the postrace CMR (postrace 10.5 ± 6% vs. follow-up 3.9 ± 3.8%, P = 0.004) and presented with a relative apical sparing distribution (P < 0.001) matched by reduction of radial peak systolic strain of basal segments (P = 0.003). Apical rotation and twist were significantly higher immediately after the competition compared with follow-up (P < 0.05).ConclusionStrenuous exercise in master triathletes is associated with a reversible regional increase in myocardial edema and reduction of radial peak systolic strain, both presenting with a relative apical sparing pattern.

Microwave-assisted synthesis, characterizations, antimicrobial activities, and DFT studies on some pyridine derived Schiff bases

This study reports a joint experimental, theoretical and microbiological investigation on the (E)-N,N-dimethyl-4-((pyridine-2-ylmethylene)amino)aniline (5), (E)-N,N-dimethyl-4-((pyridine-4-ylmethylene)amino)aniline (6) and (E)-N,N-dimethyl-4-((pyridine-3-ylmethylene)amino)aniline (7). These compounds were synthesized with microwave method and their structures characterized by FT-IR, 1H-NMR, 13C-NMR, and elemental analysis tecniques. In the theoretical studies, torsional barriers analysis, ground state structure, Fourier Transform Infrared spectra (FT-IR), and Nuclear Magnetic Resonance spectra (NMR) of 5, 6, and, 7 were calculated by Density Functional Theory (DFT) computations. The conformers obtained from the torsional barrier scanning were optimized by B3LYP/6-31G(d,p) level. The harmonic vibrational frequencies, potential energy distribution (PED), infrared intensities, and NMR chemical shifts of the most stable conformers were determined using the B3LYP/6-311++G(d,p). Theoretically, predicted spectral data were compared with experimental results. Antimicrobial studies of the synthesized compounds were performed against various microbial strains. Antimicrobial activities of 5, 6, and, 7 were tested against selected bacteria and yeast through minimum inhibitory concentration (MIC) and diffusion method. Compound 7 was found to be the most active against bacteria and yeast, while compound 5 was found to be moderately active. Compounds 6 (against S. aureus and C. albicans) and, 7 were found to have a very high minimum inhibitory concentration, ranging between 1.95 and 7.81 g/mL (against P. aeruginosa and E. coli). Compounds (6 and 7) showed zone of inhibition values in the range of 10–20 mm against other bacteria except L. monocytogenes and S. thyphimurium.

Impedance-based sub-synchronous torsional stability analysis in a HVDC system connected to multiple thermal power plants

Multiple large thermal power plants with different torsional frequencies can be successively built around the HVDC converter station, where complex torsional interactions may exist among the shafts of multiple power plants or between the power plants and HVDC system. For the torsional stability analysis of single power plant with single shaft considered, the commonly used complex torque coefficient method has been proven to be effective, but can hardly be applied to the multi-machine scenarios with multiple shafts concerned. Focusing on the sub-synchronous torsional stability of the multiple shafts of thermal power plants, this paper presents an impedance model of the thermal power plant to equivalently characterize the internal mechanical shaft characteristic to the external electrical characteristic in the sub-/super-synchronous frequency range. With the proposed model, the torsional oscillations among multiple power plant shafts and HVDC system can be conveniently been analyzed from the pure equivalent circuit perspective. Its effectiveness is evaluated for the practical Lu-Gao-Zhao HVDC system in PSCAD/EMTDC. In addition, the method introduced in this paper can also been applied to the uniform analysis of the multitype sub-synchronous oscillations in the power systems containing large amount of thermal power plants and different power electronic devices.

Retrospective analysis of liver lobe torsion in pet rabbits: 40 cases (2016-2021).

Liver lobe torsion (LLT) in rabbits can be under-recognised and potentially fatal. The clinical features of cases presented to an exotic animal veterinary service in Australia were retrospectively reviewed. Medical records of confirmed rabbit LLT cases between 2016 and 2021 were reviewed for signalment, clinical signs and findings, diagnostic imaging results, management strategies and outcomes. Variables of interest were analysed for statistical association with outcome. A total of 40 rabbits were included. The mean presenting age was 56.2 months (SD 30.5). Neutered males (23/40, 57.5%) were over-represented. Common clinical signs and findings included reduced appetite (40/40, 100%), lethargy (32/40, 80.0%), reduced faecal production (16/40, 40.0%), a doughy distended stomach (20/40, 50.0%), pale mucous membranes (19/40, 47.5%) and hypothermia (17/40, 42.5%). Anaemia and elevated plasma alanine aminotransferase and blood urea nitrogen were common clinicopathologic findings. Computed tomography (CT) was performed in 34 of 40 rabbits, confirming the presence and position of LLT (34/34, 100%), stenosis of the caudal vena cava or portal system (28/34, 82.4%) and increased free peritoneal fluid (29/34, 85.3%). Fifteen (15/40, 37.5%) rabbits were medically managed, and surgical intervention was performed in 23 of 40 (57.5%) rabbits. Overall, 30 of 40 (75.0%) rabbits survived. Surgical intervention did not confer a significant difference in outcome compared to medical management (odds ratio 0.77, 95% confidence interval 0.15-4.10, p = 0.761). CT can be an invaluable diagnostic modality for rabbit LLT. Favourable outcomes can be achieved in selected cases with medical management alone.

Dynamic torsional analysis of a functionally graded coated circular shafts weakened by multiple radial cracks

Analytical transient analysis of a functionally graded (FG) coated cylindrical bar weakened by multiple radial cracks under torsional transient loading is presented. The solution corresponding to a Volterra-type screw dislocation is achieved using the Fourier and Laplace transforms in the spatial and temporal domains, respectively. The obtained dislocation stress field is used to develop singular integral equations in terms of the unknown dislocation density function for the evaluation of multiple radial cracks. The resulting Cauchy integral equations are reduced to a set of algebraic equations and are solved numerically to determine the dislocation density functions. The achieved results are employed to evaluate the dynamic stress intensity factors (DSIFs) at the crack tips and the torsional rigidity of the FG coated circular cross-section bar with multiple embedded radial cracks. In addition, several numerical examples are presented to verify the results and to explore the effects of transient loading, FG coating layer, cracks position and interaction between them on the DSIFs and torsional rigidity of the FG coated cracked bars.