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Structure determination is necessary to identify unknown organic molecules, such as those in natural products, forensic samples, the interstellar medium, and laboratory syntheses. Rotational spectroscopy enables structure determination by providing accurate 3D information about small organic molecules via their moments of inertia. Using these moments, Kraitchman analysis determines isotopic substitution coordinates, which are the unsigned |x|, |y|, |z| coordinates of all atoms with natural isotopic abundance, including carbon, nitrogen, and oxygen. While unsigned substitution coordinates can verify guesses of structures, the missing +/− signs make it challenging to determine the actual structure from the substitution coordinates alone. To tackle this inverse problem, we develop Kreed (Kraitchman REflection-Equivariant Diffusion), a generative diffusion model that infers a molecule's complete 3D structure from only its molecular formula, moments of inertia, and unsigned substitution coordinates of heavy atoms. Kreed's top-1 predictions identify the correct 3D structure with near-perfect accuracy on large simulated datasets when provided with substitution coordinates of all heavy atoms with natural isotopic abundance. Accuracy decreases as fewer substitution coordinates are provided, but is retained for smaller molecules. On a test set of experimentally measured substitution coordinates gathered from the literature, Kreed predicts the correct all-atom 3D structure in 25 of 33 cases, demonstrating experimental potential for de novo 3D structure determination with rotational spectroscopy. [ABSTRACT FROM AUTHOR]

Temperature gradients induce mass separation in mixtures in a process called thermal diffusion and are quantified by the Soret coefficient ST. Thermal diffusion in fluid mixtures has been interpreted recently in terms of the so-called (pseudo-)isotopic Soret effect but only considering the mass and moment of inertia differences of the molecules. We demonstrate that the first moment of the molecular mass distribution, the mass dipole, contributes significantly to the isotopic Soret effect. To probe this physical effect, we investigate fluid mixtures consisting of rigid linear molecules that differ only by the first moment of their mass distributions. We demonstrate that such mixtures have non-zero Soret coefficients in contrast with ST = 0 predicted by current formulations. For the isotopic mixtures investigated in this work, the dependence of ST on the mass dipole arises mainly through the thermal diffusion coefficient DT. In turn, DT is correlated with the dependence of the molecular librational modes on the mass dipole. We examine the interplay of the mass dipole and the moment of inertia in defining the isotopic Soret effect and propose empirical equations that include the mass dipole contribution. [ABSTRACT FROM AUTHOR]

This paper describes a new method for ranking of z-numbers according to the radii of gyration in the circulating dynamics of objects. We improve the center of mass technique that was used for ranking of fuzzy data, and by using moments of inertia or second moments, we present the new method for ranking z-numbers by the Radii of Gyration (ROG). In this paper, seven principles are stated to make any ranking method of z-numbers well defined. Eventually, three different types of examples are given, first comparing two z-numbers with each other and also a comparison of the proposed approach with the existing methods is conducted. [ABSTRACT FROM AUTHOR]

The bundled parallel strand stay cables are important structural components of modern cable-stayed bridges. Strands commonly used in modern stay cables are seven-wire greased-and-sheathed strands. Stay cables primarily resist tension loads imposed by various loads, but they also resist bending stresses due to wind loads, vibration, and any traverse load applied on the cable. The movements of the deck and towers (at termination points of stay cables) also impose rotations at the cable ends, which will induce bending stresses in the strand bundles. Calculating and analyzing a stay cable's bending-induced stresses is an important consideration, especially regarding fatigue resistance. Traditionally, designers have assumed a noncomposite moment of inertia for the bundle of parallel strands because of the presumed lack of sufficient interstrand bond along the length of cables. Therefore, the composite effect is generally not considered, and the moment of inertia is typically assumed to be equal to the number of strands times the moment of inertia of an individual strand. This assumption neglects the fact that unrestrained relative slippage between strands cannot occur because the anchorage plates enforce displacement compatibility at cable ends. Also, deviation clamps and periodic cable bands (tying of the strand bundle together) along the free length of the cable may provide some degree of composite action. This study examines the global bending-induced stresses developed near the termination points of stay cables due to the application of transverse loads on the cable. Experiments and computational analyses are conducted to assess these stresses. The computational models are verified using laboratory experiments performed on a five-strand cable. Detailed and simplified finite-element models are developed. Bending-induced stress calculation procedures are developed using a simplified stay cable model. Practical Applications: This study proposes calculation procedures to address the important issue of bending-induced stresses in the design of the most crucial components of cable-stayed bridges—stay cables. At present, there are no reliable equations to estimate the maximum strand stresses due to bending action of stay cables under transverse loading. Therefore, qualification tests of relatively short stay cable specimens are sometimes utilized to evaluate fatigue resistance under bending action. For bridge design engineers, the proposed analysis approach and equations can be useful in assessing the long-term fatigue resistance of strands. This study establishes that bundles of greased-and-sheathed seven-wire strands do not act independently within the transition zone of stay cables near anchorages, and the angle change imposed due to transverse loading is not the only factor affecting bending-induced stresses. The size (number of strands) and the length of the cable are the other influential factors that must be considered. [ABSTRACT FROM AUTHOR]

The semiclassical particle-rotor model (SCM) has been used for the calculation of reduced electric quadrupole transition rates B(E2) for the νh11/2 negative parity band in 101Ru. The B(E2) values are found to exhibit a decreasing behavior with increasing spin values in the range 27/2 ℏ≤ I ≤ 47/2 ℏ. For the higher spin states, the experimental dynamic moment of inertia ℑ(2) is also in the range of AMR bands. The calculation of spin (ℏ) versus frequency (MeV) for the π(g9/2)−2⊗ν[h11/2(g7/2)2] configuration with the core contribution of 2 ℏ is found to be in good agreement with the experimental results and favors the possibility of AMR phenomenon in νh11/2 negative parity band in 101Ru. [ABSTRACT FROM AUTHOR]

Robots with parallel-link structures are generally considered useful for achieving high-speed motion; however, they are typically large in size. Robot size can be reduced by using a serial-link structure. However, their moving parts, typically having a large mass or moment of inertia, are considered unsuitable for high-speed motion. High-speed motion performance can be improved by avoiding mounting actuators on the moving parts using some method to transmit the drive force or motion. In this letter, we propose a model in which a non-pulley musculoskeletal robot, previously studied by us, is modified to avoid mounting actuators on the movable parts. We demonstrate that the robot can be controlled to achieve the target posture using this modified model. We also discuss the feasibility of high-speed motion of a prototype robot using muscular forces computed for several motion patterns based on the minimum muscle-tension change model. [ABSTRACT FROM AUTHOR]

This study proposes a novel reduced beam section concrete‐filled double steel tube (RBS CFDST) beam‐to‐column joint and investigates the effect of RBS length and the beam moment of inertia on the plastic hinge formation in such joints. Therefore, a set of nine RBS CFDST connections were fabricated and cast with self‐consolidating concrete in the laboratory. Then, parameters including failure pattern, buckling mode, plastic hinge location, joint maximum load‐bearing capacity, and column rotation were inspected. The findings reveal that when the RBS length is equal to that of the beam dimension, the entire plastic hinge length is formed within the RBS zone. As such, the plastic hinge occurs away from the column face and brittle failure is avoided, while the joint column rotation is significantly reduced. It was also concluded that the maximum load‐bearing capacity is the highest when the RBS length is at its lowest. [ABSTRACT FROM AUTHOR]

In this paper, the flexural stiffness of the reinforced concrete (RC) beams reinforced with high‐strength steel bars after exposure to different elevated temperatures was investigated experimentally and theoretically. The effects of the elevated temperature (room temperature, 200°C, 400°C, 600°C, 800°C, and 1000°C), high‐temperature duration time (0 h, 1 h, and 2 h), and steel bar types (HRB600 and HRB500) on the load–deflection response, load–stiffness response, and crack distribution of tested beams were investigated. The results showed that when the temperature is below 600°C, the effect of high temperature on the stiffness reduction of high‐strength RC beams is not significant, while the beams reduced the stiffness when the exposure temperature reached 800°C and 1000°C, regardless of the type of the steel bars. The elevated temperature accelerated the development of the deflection of RC beams, and the bending stiffness of the RC beams decreased more severely as the increase of duration time. By using appropriate degradation factors, the residual stiffness of the beams was predicted well by the analysis calculation method and the effective inertia moment calculation method, for example, the prediction accuracy is over 91% and 85.8% for the cases under and over 800°C, respectively. However, for the beams at 1000°C, a correction coefficient (0.652) was applied to improve the accuracy of the calculative stiffness of the HRB600 RC beams at the service load stage. [ABSTRACT FROM AUTHOR]

PSR J1048 |$-$| 5832 (B1046 |$-$| 58) is a Vela-like pulsar that has exhibited multiple glitch events. In this study, we analyse the timing data spanning nearly 16 yr, acquired from both the Fermi Gamma-ray Space Telescope and the Parkes 64 m radio telescope. As a result, a total of five glitches are detected within this data set. Among them, a previously unknown small glitch is newly found at MJD 56985(9) (November 24, 2014), making it the smallest glitch recorded from this source so far. The increments of the spin frequency and its first derivative are |$\Delta \nu \approx 2.2(3) \times 10^ {-8}$|  Hz, and |$\Delta \dot{\nu } \approx 3(2) \times 10^ {-15}$|  s |$^{-2}$|⁠ , respectively. Significant changes in the integrated normalized mean pulse profile are detected following three of the five glitch events, notably in the radio band. Although no evidence of a correlation is found between the spin-down rate and profile evolution, the jump phenomenon of |$W_{55}$| (pulse width at the 55% peak amplitude) after the glitch in the narrow mode suggests that the glitch may influence the profile change. We discuss the influence of glitches on the pulsar's emission properties in terms of platelet motion by a crustquake and also put constraints on the equation of state from the moment of inertia and response time-scales of involved superfluid layers inside the neutron star. [ABSTRACT FROM AUTHOR]

Lightweight electric vehicles (LEVs) possess great advantages in the viewpoint of fuel consumption, environment protection, and traffic mobility. However, due to the drastic reduction of vehicle weights and body size, the effects of inertial parameter variation in LEV control system become much more pronounced and have to be systematically estimated. This paper presents a dual adaptive unscented Kalman filter (AUKF) where two Kalman filters run in parallel to synchronously estimate vehicle inertial parameters and additional dynamic states such as vehicle mass, vehicle yaw moment of inertia, the distance from front axle to centre of gravity and vehicle sideslip angle. The proposed estimation only integrates and utilizes real-time measurements of in-wheel-motor information and other standard in-vehicle sensors in LEV. The LEV dynamics estimation model including vehicle payload parameter analysis, Pacejka model, wheel and motor dynamics model is developed, the observability of the observer is analysed and derived via Lie derivative and differential geometry theory. To address nonlinearities and undesirable noise oscillation in estimation system, the dual noise adaptive unscented Kalman filter (DNAUKF) and dual unscented Kalman filter (DUKF)are also investigated and compared. Simulation with various manoeuvres are carried out to verify the effectiveness of the proposed method using MATLAB/Simulink-Carsim®. The simulation results show that the proposed DNAUKF method can effectively estimate vehicle inertial parameters and dynamic states despite the existence of payload variations. [ABSTRACT FROM AUTHOR]

Estimation of spacecraft mass properties in the presence of noise is a nontrivial problem that, when properly addressed, can substantially reduce the crew time devoted to cargo management, control effort expended to manage fuel mass, or both. The estimation of such properties is treated here using a dual unscented Kalman filter (UKF) where the dynamics of the rigid-body spacecraft are formulated on the special Euclidean group SE (3) and its tangent bundle TSE (3) to avoid singularity and nonuniqueness issues found in attitude parameterization sets. The dual UKF on TSE (3) is developed, and a specific methodology is proposed for the estimation of the constant mass properties. An excitation approach is employed in the mass property estimation scheme. Arbitrary sensor suite placements are considered and implemented in the measurement model to capture real-world spacecraft behavior. Furthermore, a reaction control system with duty cycle constraints and noisy thrust values is implemented to account for uncertainty in the excitation inputs. With these features, the methods contained herein are found to be effective at estimating mass properties. [Display omitted] • Proposed simultaneous state and parameter estimation on TSE (3) • Performed estimation of mass, center of mass, and moment of inertia • Illustrated effective mass property estimation with noisy RCS thruster excitations [ABSTRACT FROM AUTHOR]

Products coated with flexible film can be stored in wound rolls after the winding process. However, if the roll product experiences excessive internal stress, it can lead to various defects in the coated layer. To alleviate the stress within the wound roll, a taper tension profile is utilized to progressively reduce tension as the winding length increases. As a substantial amount of web is wound onto the core, the moment of inertia of the wound roll increases. It has been observed that, as the winding length increases, the tension control performance of the taper tension tends to deteriorate. We propose an advanced taper tension profile to enhance tension control performance and validates the effectiveness of this profile through winding experiments. It was observed that, compared to the parabolic taper tension, maximum tension error could be reduced by approximately 16.1 % throughout the winding process. This reduction in tension error enables the preservation of the radial stress reduction effect of the taper tension, resulting in a 13.3 % decrease in the maximum radial stress compared to the parabolic taper tension. The proposed taper tension profile contributes to a more uniform quality of the coated layer, especially as the maximum winding length is extended. [ABSTRACT FROM AUTHOR]

We prove weighted isoperimetric inequalities for smooth, bounded, and simplyconnected domains. More precisely, we show that the moment of inertia of inner parallel curves for domains with fixed perimeter attains its maximum for a disk. This inequality, which was previously only known for convex domains, allows us to extend an isoperimetric inequality for the magnetic Robin Laplacian to non-convex centrally symmetric domains. Furthermore, we extend our isoperimetric inequality for moments of inertia, which are second moments, to p-th moments for all p smaller than or equal to two. We also show that the disk is a strict local maximiser in the nearly circular, centrally symmetric case for all p strictly less than three, and that the inequality fails for all p strictly bigger than three. [ABSTRACT FROM AUTHOR]

In this study, the influence of the torsional rigidity of the connected shafts, couplings and the working body of the machine, as well as the damping capacity of the coupling, on the torsional impact moment generated in the machine transmission is investigated. Unlike existing classical calculation models, the torsional stiffness of the connected shafts, the torsional damping ability of the coupling and the effects of the moment ratio are taken into consideration together. Under these conditions an analytical expression for the shock moment or resonance coefficient is obtained. The main novelties in obtaining of this expression are the ratio of the torsional stiffness of the connected shafts with the torsional stiffness of the coupling and the acceptance of the moment of resistance of the working body of the machine depending on the torsional stiffness. It has been found that the considered factors have a significant effect on the resonance zone. Finally, different and overlapping conditions are determined when determining the value of the resonance coefficient characterizing the torque impact moment, calculated according to the classical and proposed models. [ABSTRACT FROM AUTHOR]

Flywheels used for energy storage may be assembled by press fitting or bonding of concentric rotor parts. During operation, each part is subjected to a superposition of stress fields associated with centrifugal loading and with contact at the component interfaces. To capture the highest overall energy storage capacity, design properties must be selected to achieve the maximum moment of inertia, subject to constraints on the stress occurring within each part at the maximum operating speed. This paper proposes a mathematical formulation for parametric shape optimization problems which can be used to design a multi-disk flywheel rotor to maximize the energy storage capacity. It is shown that the energy storage function for each part of the flywheel can be expressed as a product of two fundamental shape-factors: one that accounts for the stress distribution and the other accounts for the mass distribution. These factors are expressed analytically for cases involving hyperbolic disks, leading to a finite dimension shape optimization problem for a multi-disk rotor. Case studies are presented based on the derived analytical solutions that show how the theory can be usefully applied in flywheel design optimization problems. The results from the case study show significant improvements in specific energy compared to previous research results. This advancement is particularly relevant to develop high-performance, cost-effective flywheel systems, offering potential for widespread application in energy storage technologies. [ABSTRACT FROM AUTHOR]

The post-capture control of tethered debris can be challenging due to its unresponsive and uncooperative nature. Often, control of debris may require knowledge of the moments of inertia, which are usually unknown. This study applies an Unscented Kalman Filter to estimate the attitude, angular rates, and principal moments of inertia of debris captured via a tether. The filter utilizes tension and pixel-coordinate measurements of various landmarks on the debris to achieve estimation. Due to the translational and rotational motion of the debris, landmarks can be occluded or exit the field of view of the camera. Different control profiles are applied to the chaser to investigate the effects of the tension in the tether and of the visibility of chosen landmarks. It is found that large tension in the tether does not provide more accurate estimates, but that prolonging transient tether behavior improves the accuracy and precision of moment of inertia estimates. It is further observed that lower tension magnitudes with longer visibility times of landmarks make estimation of the inertia parameters possible with fewer tracked landmarks. [ABSTRACT FROM AUTHOR]

Methods are lacking that can prepare deuterium-enriched building blocks, in the full range of deuterium substitution patterns at the isotopic purity levels demanded by pharmaceutical use. To that end, this work explores the regio- and stereoselective deuteration of tetrahydropyridine (THP), which is an attractive target for study due to the wide prevalence of piperidines in drugs. A series of d0–d8 tetrahydropyridine isotopomers were synthesized by the stepwise treatment of a tungsten-complexed pyridinium salt with H−/D− and H+/D+. The resulting decomplexed THP isotopomers and isotopologues were analyzed via molecular rotational resonance (MRR) spectroscopy, a highly sensitive technique that distinguishes isotopomers and isotopologues by their unique moments of inertia. In order to demonstrate the medicinal relevance of this approach, eight unique deuterated isotopologues of erythro-methylphenidate were also prepared. Deuteration of active pharmaceutical ingredients is increasingly applied as the isosteric and isotopic replacement can modulate the pharmacokinetic profile, without necessarily having to alter the overall synthetic strategy toward the compound of interest. Here, the authors show manifold deuterations of piperidines and apply molecular rotational resonance (MRR) spectroscopy as a methodology to distinguish isotopomers within a distribution of products. [ABSTRACT FROM AUTHOR]

This paper is concerned with the well-posedness and long-time dynamics of a class of beam/plate equations with rotational inertia and nonlinear energy damping. The model is derived from nonlocal dissipative energy models for flight structures, as proposed by Balakrishnan-Taylor (Proceedings Damping 89, Flight Dynamics Lab and Air Force Wright Aeronautical Labs, WPAFB, 1989). Our main results address the existence of compact global attractors. The work complements the degenerate coefficient case left open by Sun and Yang (J. Math. Anal. Appl., Volume 512, Issue 2, 2022). [ABSTRACT FROM AUTHOR]

The primary objective of this study is to conduct a thorough examination of relativistic structures within the framework of f (ℛ ,) gravity, where ℛ is the Ricci scalar and is the trace of the energy–momentum tensor. We investigate the emerging characteristics of compact stars, focusing on the ℛ + 2 ξ model, where ξ is the coupling constant. In the initial sections of the paper, we concentrate on the examination of exact interior solutions involving perfect fluid. With this aim, we introduce the metric coefficient L = S (1 + 2 a r 2) d / 2 , where a and S are arbitrary constants to be computed from the matching conditions and d is a positive odd integer. It is worth noticing that we select a group of 10 significant compact stars from recent studies, namely, Vela X − 1 , EXO 1 7 8 5 − 2 4 8 , 4 U 1 8 2 0 − 3 0 , SMC X − 4 , Her X − 1 , PSR J 1 6 1 4 − 2 2 3 0 , PSR J 1 9 0 3 + 3 2 7 , Cen X − 3 , 4 U 1 5 3 8 − 5 2 and LMC X − 4. To investigate the viability of our model, we conduct various checks, including the analysis of energy density and pressure components, equilibrium, and energy conditions, stability analysis and the adiabatic index. An important part of this work provides the slowly rotating property of stars, accompanied by the derivation of the moment of inertia. The relationship of mass, energy density, radius and moment of inertia for stellar objects are observed. Our findings demonstrate that obtained results are physically acceptable and consistent with our considered model. [ABSTRACT FROM AUTHOR]

By using the quadratic equation of state and the anisotropic energy-momentum tensor for compact stars in spherically symmetric spacetime in hydrostatic static equilibrium to solve Einstein's field equation, we are able to create a new class of models for compact stars. We developed new solutions by solving the field equations for the distribution of matter using a well-known Buchdahl metric potential (Buchdahl in Phys. Rev. D 116:1027, 1959). The resulting anisotropic solutions exhibit good behavior and obey the energy conditions. By analyzing the TOV equation, we have confirmed the stability of the produced model, Harrison-Zeldovik-Novikov criterion, and the adiabatic index for the solution. The fulfillment of all these criteria makes this model to be utilized for the study of realistic compact objects. Also, we measured the masses and radii of star candidates like "4U 1820-30", "PSR J1903+327", "4U 1608-52", "Vela X-1", "PSR J1614-2230", and "Cyg X-2" through this model and found these values compatible with observational values of corresponding stars. For each of the considered compact stars, we have obtained the approximate value of the moment of inertia via the obtained solution. [ABSTRACT FROM AUTHOR]

Flexural hybrid reinforced concrete members with fiber reinforced polymer (FRP) and steel bars (hybrid-RC) exhibit significant post-yielding stiffness due to the contribution of tensile FRP bars. To predict the post-yielding deflection of hybrid-RC members, the Bischoff's model for effective moment of inertia is extended into the post-yielding stage. Based on this extended model, expressions for equivalent moment of inertia, which consider the variation in stiffness along the member span with and without tension stiffening, are proposed. Obtaining close-formed solutions for the yielding moment of hybrid-RC cross sections, a critical parameter for determining the post-yielding effective moment of inertia, proves challenging due to the unknown state of compressive concrete. Therefore, a simplified equation to determine the yielding moment are proposed by regression of data derived from numerical sectional analyses. An experimental database including 92 hybrid-RC beams collected from published literature is established. The performance of the proposed equation for the yielding moment and expressions for the equivalent moment of inertia are evaluated using the database. The results indicate that the proposed equation can effectively predict the yielding moments of hybrid-RC beams. Furthermore, using a constant effective moment for predicting the post-yielding deflection is effective for the specimens with relatively high reinforcement ratios. The benefit of considering the stiffness variation along the member span is evident when dealing with lightly-reinforced concrete members. [ABSTRACT FROM AUTHOR]

This paper reviews how multifunctioning joints produce highly agile limbs in animals with lessons for robotics. One of the key reasons why animals are so fast and agile is that they have multifunctioning joints in their limbs. The multifunctioning joints lead to a high degree of compactness which then leads to a host of benefits such as low mass, low moment of inertia and low drag. This paper presents three case studies of multifunctioning joints—the human wrist joint, knee joint and foot joints—in order to identify how multifunctioning is achieved and what lessons can be learned for robotics. It also reviews the multifunctioning nature of muscle which plays an important role in joint actuation. A key finding is that multifunctioning is achieved through various means: multiple degrees of freedom, multifunctioning parts, over-actuation and reconfiguration. In addition, multifunctioning is achieved through highly sophisticated layouts with high levels of integration and fine-tuning. Muscle also makes an important contribution to animal agility by performing multiple functions including providing shape, protection and heat. The paper reviews progress in achieving multifunctioning in robot joints particularly for the wrist, knee and foot. Whilst there has been some progress in creating multifunctioning robotic joints, there is still a large gap between the performance of animal and robotic joints. There is an opportunity to improve the agility of robots by using multifunctioning to reduce the size and mass of robotic joints. [ABSTRACT FROM AUTHOR]

Free-falling of objects in fluids is universal in nature and engineering. The falling styles of the falling object are affected by the properties of both the object and the fluid. Based on the assumption that the final state of a free-falling object at low Reynolds numbers is stable and equivalent to that of a fixed object with incoming flow, we utilize the results for the fixed plate to interpolate and obtain the state of the falling plate. It is found that the plate would exhibit multiple stable falling solutions. The number of stable falling solutions is dependent on the location of the gravity center of the plate. The distribution of the multi-solution region is affected by both Archimedes number (Ar) and the density ratio ( m * ). The results of the actual fall of the plate do not always agree with those obtained by the static interpolation method due to the fact that the fall of the plate is a dynamic process. We simulate the falling behaviors of plates whose center of gravity is located in the multi-solution region for different initial release angles θ 0 . According to the falling behaviors of the plate, there are four regions that are observed and denoted in the multi-solution region: (1) single stable region; (2) bistable region; (3) single stable and fluttering region; and (4) bistable and fluttering region. The effects of Ar, m * , and the dimensionless moment of inertia I * of the plate on the distribution of the four regions are evaluated. [ABSTRACT FROM AUTHOR]

The moment of inertia of the primary flywheel and the secondary flywheel in a dual mass flywheel (DMF) directly affects the vibration damping performance in an automotive driveline. To enable better minimization of vibration and noise by changing the moment of inertia of the DMF to adjust the frequency characteristics of the automotive driveline, a new variable inertia DMF structure is proposed by introducing electromagnetic devices. The finite element simulation model of the electromagnetic field of an electromagnetic device is established, the electromagnetic field characteristics in the structure are analyzed, and the variation in the electromagnetic force under different air gaps and current conditions is obtained. The electromagnetic force test system of the electromagnetic device is constructed, and the validity of the finite element simulation analysis of the electromagnetic field of the electromagnetic device is verified. A mechanical model of the electromagnetic device is established to analyze the characteristics of the displacement of the moving mass in the structure as well as the variation in the moment of inertia of the DMF at different rotational speeds and currents. The maximum adjustable proportion of its moment of inertia can reach 15.07%. A torsional model of the automotive driveline is established to analyze the effect of variable inertia DMF on the resonance frequency of the system under different currents. The results show that the electromagnetic device introduced in the DMF can realize the active adjustment of the moment of inertia and enable the resonance frequency to decrease with increasing rotational speed, which expands the idea of optimizing the vibration damping performance of the DMF and provides a reference for better control of the torsional vibration of the automobile or other mechanical transmission systems. [ABSTRACT FROM AUTHOR]

Side and frontal airbag deployment represents the main injury mechanism to the upper extremity during automotive collisions. Previous dynamic injury limit research has been limited to testing the forearm at either the assumed most vulnerable location to fracture, the distal 1/3rd, or the midpoint. Studies have varied the surface to which impacts were applied, with no clear consensus on the site of greatest vulnerability. The unpredictability of airbag impact location, especially with altered hand positioning, limits the effectiveness of existing forearm injury limits determined from impacts at only one location. The current study quantified the effect of impacts at alternative locations on injury risk along the forearm using the THUMS FE model. Airbag-level impacts were simulated along the forearm on all four anatomical surfaces. Results showed the distal 1/3rd is not the most vulnerable location (for any side), indicating forearm fracture is not solely driven by area moment of inertia (as previously assumed). The posterior forearm was the weakest, suggesting that current test standards underestimate the fracture risk of the forearm. Linear regression models showed strong correlation between forearm fracture risk and bone geometry (cross-sectional area and area moment of inertia) as well as soft-tissue depth, potentially providing the ability to predict forearm injury tolerances for any location or forearm size. This study demonstrated the forearm's vulnerability to fracture from airbag deployments, indicating the need for safety systems to better address injury mechanisms for the upper limb to effectively protect drivers. [ABSTRACT FROM AUTHOR]

This research proposes an innovative method to convert the modeling of three-dimensional structures to the modeling of two-dimensional structures for the stability analysis of long tubular buildings. The process of the proposed method is in the form of modeling the equivalent frame and then modeling the reduced frame using the equivalent moment of inertia for beams and columns. The second-order elastic analysis has been performed considering the effects of P-Δ and P-δ. Framed-tube and frame tube-in-tube systems have been used for modeling. Newton's Raphson and Crisfield's Arc Length methods have also been used for nonlinear analysis. The accuracy and speed of analysis of the new method have been checked by comparing the displacements and drifts in the modeled systems for 40 and 50 stories tall buildings. For each structure, two framed-tube and tube-in-tube systems are considered. In the presented method, the number of nodes and elements in the reduced model is much less. The method presented in this research can reduce the amount of calculating the response of tall structures and the duration of the analysis. One of the advantages of the presented method is the acceptable accuracy of the analysis along with the high speed of the analysis. The results show that the proposed method has reduced the amount of calculations by 80% along with a 5% reduction in the accuracy of structural responses. [ABSTRACT FROM AUTHOR]

The Chandler period of Mars is a new parameter determined from observational data that characterizes the properties of the planetary interior. Numerical modeling of the period of the Chandler wobble of Mars was performed for a number of internal structure models that satisfy not only geodetic data (moment of inertia, tidal Love number k2), but also data obtained during a seismic experiment in the years 2019–2022. To reconcile the theoretical and observed values of the Chandler wobble, it is necessary to take into account the inelasticity of the mantle. To take into account the viscoelastic behavior of the interior, the Andrade rheological model was used. It is demonstrated how the value of the Chandler period depends on the rheological model parameters. [ABSTRACT FROM AUTHOR]

Ojhung is one of the indigenous Indonesian cultures from Sumenep Regency which contains relevant science concepts to be applied in science learning. Therefore, this research aimed to identify and explore the concepts of science contained in the Ojhung tradition while evaluating their relevance to the Merdeka or national curriculum. This research uses a qualitative design with a grounded theory based on scientific concepts in the Ojhung tradition and can be applied in science learning. The concepts of science that have been successfully explored and identified are Newton's Third Law, Sound Waves, Sense of Hearing, Pressure, Flexibility, Body Muscles, Moments of Inertia, and Skin Wounds. All concepts that have been explored can actualise learning outcomes in the Merdeka Curriculum. This research implies applying science concepts to Ojhung to improve public scientific literacy and science learning in schools. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

For floating offshore wind turbines, a significant pitch and roll motion response of the platform can affect the acceleration and power generation of the nacelle. The damping plate is considered a type of attachment that can be used to reduce rotational motion, but research on its anti-rotational effect is limited. The objective of this work is to analyze the impact of installing damping plates and varying their sizes on the pitch motion response of semi-submersible platforms, while also proposing optimization strategies for damping plate design. Firstly, a comparison between numerical simulations and experimental measurements validates the accuracy of the CFD calculations. Subsequently, different sizes of damping plates are proposed for the platforms, followed by simulations under various conditions. Finally, comprehensive data analysis is conducted. The findings suggest that installing damping plates enhances both the platform's added moment of inertia and damping coefficients while simultaneously amplifying its motion response in regular waves. Furthermore, increasing the size of damping plates leads to an increase in both the added moment of inertia and motion response for the platform, whereas the damping coefficient exhibits an initial increasing trend followed by a subsequent decrease. Ultimately, it is found that increasing the distance between damping plates and the free surface significantly reduces wave-induced loads on the platform. [ABSTRACT FROM AUTHOR]

The widespread use of Unmanned Underwater Vehicles (UUVs) in seafloor observatory networks highlights the need for docking stations to facilitate rapid recharging and effective data transfer. Floating docks are promising due to their flexibility, ease of deployment, and recoverability. To enhance understanding and optimize UUV docking with floating docks, we employ dynamic fluid body interaction (DFBI) to construct a seabed moored suspended dock (SMSD) model that features a guiding funnel, a suspended body, and a catenary of a mooring chain. This model simulates SMSD equilibrium stabilization in various ocean currents. Then, a UUV docking model with contact coupling is developed from the SMSD model to simulate the dynamic contact response during docking. The accuracy of the docking model was validated using previous experimental data. Through investigation of the UUV docking response results, sensitivity studies relating to volume, moment of inertia, mass, and catenary stiffness were conducted, thereby guiding SMSD optimization. Finally, sea tests demonstrated that the SMSD maintained stability before docking. During docking, the SMSD's rotation facilitated smooth UUV entry. After the UUV docked, the SMSD was restored to its original azimuth, confirming its adaptability, stability, and reliability. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The millimeter-wave rotational spectrum of ketene (H2C=C=O) has been collected and analyzed from 130 to 750 GHz, providing highly precise spectroscopic constants from a sextic, S-reduced Hamiltonian in the Ir representation. The chemical synthesis of deuteriated samples allowed spectroscopic measurements of five previously unstudied ketene isotopologues. Combined with previous work, these data provide a new, highly precise, and accurate semi-experimental (reSE) structure for ketene from 32 independent moments of inertia. This reSE structure was determined with the experimental rotational constants of each available isotopologue, together with computed vibration–rotation interaction and electron-mass distribution corrections from coupled-cluster calculations with single, double, and perturbative triple excitations [CCSD(T)/cc-pCVTZ]. The 2σ uncertainties of the reSE parameters are ≤0.0007 Å and 0.014° for the bond distances and angle, respectively. Only S-reduced spectroscopic constants were used in the structure determination due to a breakdown in the A-reduction of the Hamiltonian for the highly prolate ketene species. All four reSE structural parameters agree with the "best theoretical estimate" (BTE) values, which are derived from a high-level computed re structure [CCSD(T)/cc-pCV6Z] with corrections for the use of a finite basis set, the incomplete treatment of electron correlation, relativistic effects, and the diagonal Born–Oppenheimer breakdown. In each case, the computed value of the geometric parameter lies within the statistical experimental uncertainty (2σ) of the corresponding semi-experimental coordinate. The discrepancies between the BTE structure and the reSE structure are 0.0003, 0.0000, and 0.0004 Å for rC–C, rC–H, and rC–O, respectively, and 0.009° for θC–C–H. [ABSTRACT FROM AUTHOR]

This paper presents a novel Flexnertia metastructure concept to perform vibration suppression through coupling rotational inertia to structural flexural motion. Theoretical analysis and experimental test of the proposed metastructure with emphasis on dissipating structural flexural motion is exhibited, showing vibration control performance. The experimental and numerical results are in good agreement, both confirming that the average overall response of the metastructure is significantly reduced. The attenuation becomes most pronounced in the low-frequency range where structures tend to suffer most due to high response around the regime of the first flexural modes. [ABSTRACT FROM AUTHOR]

Based on the PREM Earth model, more than a thousand models of the internal structure of Venus have been built, differing in the radius and density of the core, the density of the mantle, the viscosity distribution and rheology. The core radius varies from 2800 to 3600 km, and the density in the mantle and core varies within a few percent of the PREM model values. When calculating tidal Love numbers, Andrade rheology is used to take into account the inelasticity of the mantle. Specifically the values of the Andrade rheological model parameters that best describe the tidal deformation of the Earth are used. This significantly reduces the error when calculating Love numbers. It has been shown that Venus can have an internal solid core only if the composition of the planet is very different from that of Earth. Comparison of the observed values of the moment of inertia and tidal Love number k2 with model values allowed us to conclude that the radius of the core of Venus is with a high probability in the range of 3288 ± 167 km. [ABSTRACT FROM AUTHOR]

The results of numerical modeling of the values of the Chandler wobble period of Mars have been presented for a set of internal structure models that satisfy all currently available observable data: geodetic (average radius, mass, moment of inertia, tidal Love number k2) and crustal thickness and core radius values obtained from seismic data processing. Andrade rheology was used to take into account inelasticity when calculating model values of the tidal Love number k2 and the Chandler wobble period. It has been shown how the model values of the Love number k2 and the Chandler period depend on the Andrade rheological parameter and the adopted viscosity distribution. [ABSTRACT FROM AUTHOR]

The utilization of renewable energy sources, particularly large-scale photovoltaic plants (PVPs), has been increasing in power systems. However, the high penetration of PVPs in power systems has implications for the system's moment of inertia and frequency response. Therefore, it is crucial to thoroughly investigate the impact of PVPs on system frequency. This study focuses on investigating the effects of a large-scale PVP at various penetration levels on frequency and the depth of frequency support. The study proposes a strategy aimed at maximizing power generation from PVPs while also providing support to system frequency. To assess the effects of PVPs, the study examines events such as load outages, generator outages, load changes, and three-phase short circuits. Additionally, the relationship between voltage and frequency during these events is considered, with the load represented by an impedance model. By studying the depth of frequency support alongside different penetration levels, the study provides a detailed understanding of the impact of PVPs on frequency. The study aims to determine the threshold at which the penetration level of PVPs becomes significant in terms of frequency support. This analysis sheds light on the point at which the presence of PVPs begins to exert a notable influence on frequency stability and support within the power system. Overall, the study contributes to the integration of PVPs in power systems by providing insights into their impact on frequency dynamics and proposing strategies to enhance power generation and frequency support simultaneously. [ABSTRACT FROM AUTHOR]

Tapered beams are characterized by varying moments of inertia along their span, commonly the pier cap configuration used in bridge construction. This study presents the shear behavior of tapered beams reinforced with basalt fiber–reinforced polymer (BFRP) bars through experiments and analyses. Eight BFRP beams were tested to explore the influence of changing inclination angles and the presence of BFRP stirrups. These beams were divided into two groups, each consisting of four beams: one control straight beam and three tapered beams with different tapered angles. The first group was without shear reinforcement, while the second group was reinforced with BFRP stirrups. Results revealed that increasing tapered angles decreased the shear strength of BFRP tapered beams without stirrups but increased it in beams with BFRP stirrups. The analytical part proposed equations to estimate the shear strength of BFRP tapered beams, with findings indicating conservative estimations consistent with experimental data trends. [ABSTRACT FROM AUTHOR]

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AbstractThe present work models and studies the resonance frequency change due to adsorption phenomena in a simply-supported adatom-microbeam system under an axial magnetic environment. The microbeam structure is a functionally graded (FG) sandwich that includes a rectangular configuration and a ceramic perforated core with periodic square holes network and FG porous material faces. To evaluate the adsorption-induced energies produced by van der Waals interaction (vdW), the Morse and Lennard-Jones (6–12) potentials are included in conjunction with nonlocal material elasticity to adopt the small-scale impact. Moreover, the explicit formulas for the inertia moments and shear force are developed by the Timoshenko beam equations, considering the residual stress influence as an additional axial load. The Navier-type solution and the differential quadratic method (DQM) are implemented to compute the solution of the governing equations. It is established that the resonance frequency change for the O/Si (100) and H/Si (100) is dependent on the geometrical, perforation, and porosity parameters, adsorption density, mode number, and the magnetic field intensity as well. Therefore, these numerical results have been discussed in detail to properly examine dynamic vibration behavior and a suitable mass detection design of M/NEMS structures. [ABSTRACT FROM AUTHOR]

Introduction: Muscles play a critical role in supporting joints during activities of daily living, owing, in part, to the phenomenon of short-range stiffness. Briefly, when an active muscle is lengthened, bound cross-bridges are stretched, yielding forces greater than what is predicted from the force length relationship. For this reason, short-range stiffness has been proposed as an attractive mechanism for providing joint stability. However, there has yet to be a forward dynamic simulation employing a cross-bridge model, that demonstrates this stabilizing role. Therefore, the purpose of this investigation was to test whether Huxley-type muscle elements, which exhibit short-range stiffness, can stabilize a joint while at constant activation. Methods: We analyzed the stability of an inverted pendulum (moment of inertia: 2.7 kg m2) supported by Huxley-type muscle models that reproduce the short-range stiffness phenomenon. We calculated the muscle forces that would provide sufficient short-range stiffness to stabilize the system based in minimizing the potential energy. Simulations consisted of a 50 ms long, 5 Nm square-wave perturbation, with numerical simulations carried out in ArtiSynth. Results: Despite the initial analysis predicting shared activity of antagonist and agonist muscles to maintain stable equilibrium, the inverted pendulum model was not stable, and did not maintain an upright posture even with fully activated muscles. Discussion & conclusion: Our simulations suggested that short-range stiffness cannot be solely responsible for joint stability, even for modest perturbations. We argue that short-range stiffness cannot achieve stability because its dynamics do not behave like a typical spring. Instead, an alternative conceptual model for short-range stiffness is that of a Maxwell element (spring and damper in series), which can be obtained as a first-order approximation to the Huxley model. We postulate that the damping that results from short-range stiffness slows down the mechanical response and allows the central nervous system time to react and stabilize the joint. We speculate that other mechanisms, like reflexes or residual force enhancement/depression, may also play a role in joint stability. Joint stability is due to a combination of factors, and further research is needed to fully understand this complex system. [ABSTRACT FROM AUTHOR]

The active angular absorber for angular vibration control is proposed. Characteristics of the angular absorber are analyzed and an experiment is performed. The active angular absorber consists of a base and two identical voice coil actuators. The actuators have central symmetry and the coils are series connected to get the same current so that they output inertia forces with the same amplitude in opposite directions. There is a certain distance between the axes of the two actuators to produce a moment from the inertia forces, which can be employed to actively control the angular vibration. First, the mechanics of the angular absorber are presented. Then, the dynamic model of an angular vibration system with the absorber is demonstrated and the control law is proposed. Parameters of the absorber are discussed, showing that the absorber has the advantages of reliable structure and flexibility for installation. Next, numerical simulation is performed and the results show that the control method is effective and the simplification of the dynamic model is reasonable. Finally, a prototype of the absorber is produced and the angular vibration control experiment is conducted. Test results show that angular vibration with the amplitude of 1" level and at a frequency of 6 Hz can be attenuated by 93% to the level of the noise, while vibration at 0.1" level and 46 Hz can be attenuated by 80.7% to 0.01". The control process is rapid and convergence is stable. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A long rigid-flexible coupling transmission shaft (RFCTS) is usually used to connect the dynamometer with the device under test (DUT) in semi-anechoic chamber. However, due to the parameter error and torsional vibration characteristic of RFCTS, load emulation loading accuracy of the test bench is lower. Therefore, the research focused on establishing a control-oriented vehicle powertrain system test bench (VPSTB) model based on RFCTS to further improve the load emulation loading accuracy. First, a 14-degrees of freedom (DOF) high-order lumped mass model of VPSTB is established, and the stiffness and moment of inertia equivalent parameters are obtained. Subsequently, a 7-DOF simplified control-oriented VPSTB model is established based on 14-DOF model, and the model parameters are identified by the recursive least squares estimation (RLSE) method with forgetting factor. Simultaneously, the natural frequency of 14-DOF high-order model and 7-DOF simplified model is calculated, then un-damped vibration response of the two models are compared and analyzed. Finally, simulation and experimental are carried out under open-loop and closed-loop conditions, which show that the effectiveness of 7-DOF simplified model parameters, and it also indicate that the 7-DOF simplified VPSTB model can achieve better loading accuracy of load emulation. [ABSTRACT FROM AUTHOR]