Effects Of Structural Flexibility Research Articles

Why knowledge integration ability differs: team co-creation and sharing climate as a mediating variable

The richness of material life and the progress of digital technology have largely promoted the development of the knowledge economy, and the team's ability to integrate knowledge has increasingly become the key to the competitive advantage of enterprises, and the knowledge base theory also points out that knowledge is the core resource for enterprises to participate in the competition, especially the importance of tacit knowledge is more and more highlighted nowadays. Therefore, this study was conducted based on 528 valid questionnaires and tested the hierarchical regression model with the help of SPSS. The study reveals the mechanism of the positive effect of corporate structural flexibility on team knowledge integration ability and the realisation path of the positive effect of employees' career growth on team knowledge integration ability and finds for the first time that the use of digital technology weakens the positive effect of structural flexibility on team knowledge integration ability.

Experimental and Numerical Prediction of Slamming Impact Loads Considering Fluid–Structure Interactions

Slamming impacts on water are common occurrences, and the whipping induced by slamming can significantly increase the structural load. This paper carries out an experimental study of the water entry of rigid wedges with various deadrise angles. The drop height and deadrise angle are parametrically varied to investigate the effect of the entry velocity and wedge shape on the impact dynamics. A two-way coupled approach combing CFD method software STAR-CCM+12.02.011-R8 and the FEM method software Abaqus 6.14 is presented to analyze the effect of structural flexibility on the slamming phenomenon for a wedge and a ship model. The numerical method is validated through the comparison between the numerical simulation and experimental data. The slamming pressure, free surface elevation, and dynamic structural response, including stress and strain, in particular, are presented and discussed. The results show that the smaller the inclined angle at the bottom of the wedge-shaped body, the faster the entry speed into the water, resulting in greater impact pressure and greater structural deformation. Meanwhile, studies have shown that the bottom of the bow is an area of concern for wave impact problems, providing a basis for the assessment of ship safety design.

Excellent comprehensive electrical properties in KNN-based ceramics via synergistic effects of structural flexibility and domain engineering

A large d33 value of 483 pC N−1 and a high TC of 302 °C can be simultaneously obtained in KNNT-BNZ-BFO/0.004 LiF ceramics. The prototype device of KNNT-BNZ-BFO/0.004 LiF buzzers is fabricated, and its SPL reaches 95–98 dB at 4–5 kHz.

Effect of Structural Flexibility of Wheelset/Track on Rail Wear

To investigate the influence of the structural deformation of the wheelset and track on rail wear in the longitudinal and lateral directions, a rail wear prediction model is established that can calculate the three-dimensional distribution of rail wear. The difference between the multi-rigid-body dynamic model and the rigid-flexible coupled dynamic model, which considers the structural flexibility of the wheelset and track, is compared in terms of the three-dimensional distribution of rail wear. The results show that the three-dimensional distributions of rail wear predicted by the two models are relatively similar. There is no obvious difference in the wear band, and the rail wear in the longitudinal direction is almost identical. The cross sections of the worn rail shapes determined by the two models are essentially the same, with a maximum difference of 3.6% in the average value of the wear areas of all cross sections. The track irregularity is the main reason for the uneven distribution of rail wear in the longitudinal direction. The position where the rail wear is more pronounced hardly varies with the evolution of the rail wear. It is recommended to use a multi-rigid-body dynamic model for the prediction of rail wear, which allows both calculation accuracy and efficiency.

Effects of structural flexibility on the dynamic responses of low-height lifting mechanism for offshore wind turbine installation

Installation complexities are one of the major challenges in the floating offshore wind turbine (OWT) industry. The modern concept introduced by the SFI-MOVE project is an effort to overcome the complexities by utilizing a low-height lifting mechanism. It is common to idealize a crane in the lifting mechanism as a rigid body since the structural deflections are smaller than the responses introduced by the other system components. However, structural flexibility can play an essential role in demanding offshore operations with smaller acceptable tolerances. In this study, lifting cranes are modeled using the finite element method and simplified by implementing equivalent 3D beam elements. Dynamic analysis is performed for various environmental conditions, and the responses of the crane structure and the OWT are calculated for each load case. This research reveals that crane structure flexibility influences the relative motion between a floating spar buoy and an OWT during mating operations. Crane structural flexibility contributes significantly to the OWT rotations. In addition, the response deviation between using rigid and flexible cranes increases as the excitation force increases. Therefore, it is recommended to consider the crane structural flexibility in the calculation when strict installation tolerances are needed.

Theoretical Study of Oxygen Reduction Reaction Mechanism in Metal-Free Carbon Materials: Defects, Structural Flexibility, and Chemical Reaction.

Metal-free carbon materials are attractive Pt-based catalyst alternatives. However, despite efforts, the reaction mechanism remains elusive. Thus, we investigated the role of defects (dopant nitrogen and carbon vacancy) on the catalytic oxygen reduction reaction in a metal-free carbon material focusing on the effect of structural flexibility. Crucially, defects lower the energy barrier for the sp2/sp3 transition of the carbon-centered O2-adsorption sites by releasing structural strain during the reaction. In particular, low-coordinated pyridinic-N displaces from the carbon plane to release the strain, whereas weak C-C bonds around the carbon vacancy change the bond lengths to release the strain. Defects indirectly promote the adsorption of oxygen by enhancing structural flexibility. Thus, the nonlocal structural environment is as critical as the direct interaction between adsorption sites and adsorbate in the chemical reaction. Molecular dynamics simulations reveal that pyridinic-N doping is a facile route to introduce stable catalytic active sites. Overall, our results provide a deeper understanding of chemical processes on defective carbon materials.

BSA Interaction, Molecular Docking, and Antibacterial Activity of Zinc(II) Complexes Containing the Sterically Demanding Biomimetic N3S2 Ligand: The Effect of Structure Flexibility.

Two zinc(II) complexes, DBZ and DBZH4, that have (ZnN3S2) cores and differ in the bridging mode of the ligating backbone, effectively bind to BSA. The binding affinity varies as DBZ > DBZH4 and depends on the ligand structure. At low concentrations, both complexes exhibit dynamic quenching, whereas at higher concentrations they exhibit mixed (static and dynamic) quenching. The energy transfer mechanism from the BSA singlet excited state to DBZ and DBZH4, is highly likely according to steady-state fluorescence and time-correlated singlet photon counting. Molecular docking was used to support the mode of interaction of the complexes with BSA and showed that DBZ had more energy for binding. Furthermore, antibacterial testing revealed that both complexes were active but to a lesser extent than chloramphenicol. In comparison to DBZH4, DBZ has higher antibacterial activity, which is consistent with the binding constants, molecular docking, and particle size of adducts. These findings may have an impact on biomedicine.

Three-Dimensional Numerical Modeling of a Coastal Highway Bridge under Stokes Waves

This article investigated the effect of structural flexibility on a coastal highway bridge subjected to Stokes waves through a three-dimensional numerical model. Wave-bridge interaction modeling was performed by an FSI model with the coupling of finite element and finite volume methods. An experimental model validated the FSI numerical analysis. Eventually, the overall results of hydrodynamic and structural analyses are presented and discussed. The results illustrate that the structural flexibility significantly increases the initial shock of the wave force on the flexible bridge. In contrast, the fixed bridge tolerates the least forces in the initial shock of the wave force. Then, by adding a wedge-shaped part to the bridge structure, an attempt was made to reduce the initial shock of the wave force to the structure. The results showed the wedge-shaped part with an angle of 30° reduces the initial shock of wave forces down to 50% for horizontal force and 43% for vertical force on the flexible structure.

PZT Actuators’ Effect on Vibration Control of the PRRRP 2-DOF Flexible Parallel Manipulator

Thanks to their advantages over rigid ones, interest for lightweight parallel manipulator was increased. Besides, structural flexibility effects at high operational speeds are more significant. Thus, developing an appropriate model for the assessment of the dynamic properties of flexible mechanisms and linkages to gain effective vibration control will raise high demand. Therefore, this paper represents the dynamic and kinematic modeling using the assumed mode method and first-type Lagrange equations of the 2-DOF planar parallel manipulator with two flexible links. To truly predict vibrations of the manipulator without any major simplifying assumptions, nonlinear dynamic modeling, which thoroughly attempts to represent the flexible behavior of the links, is considered. As a result, an active damping approach is being studied with PZT actuators. The results show that this approach is effective in damping the vibrations of the links that give accurate trajectory control.

Thermal coupling-decoupling mechanism of heat transfer across van der Waals interfaces in n-eicosane

Progress toward improving thermal transport properties of n-eicosane, a promising phase change material for thermal energy storage near human body temperature, is hindered by lack of a general theoretical framework to model thermal interfacial conductance (TIC) of the van der Waals (vdW) force bonded molecular interfaces, which have little compositional/structural mismatch. Combining molecular dynamics simulations at temperatures up to the melting point and a time-domain analysis of interfacial heat currents in individual molecules, we unveil that (1) the heat flux across a molecular vdW interface has an alternating coupling-decoupling pattern at the single molecule level due to thermal fluctuations, and (2) the net heat transfer during the thermally coupled periods is orders of magnitude larger than that during the thermally decoupled periods. Furthermore, we demonstrate that a vdW interface's TIC correlates almost linearly with two atomistic-scale coupling-decoupling parameters: αc and σc, that represent the duration and strength of the thermal coupling, respectively. This thermal coupling-decoupling mechanism proposes a new paradigm that explicitly accounts for the effects of structural flexibility and dynamical fluctuation on heat transfer across molecular interfaces, and will likely provide new insights into modeling thermal transport properties in a wide-ranging soft materials, including self-assembled monolayers, paraffins or lipids.

Regioselective Chemical Modification of Cysteine Residues on Protein Surfaces Focusing on Local Environment around the Conjugation Site.

For chemical modification of cysteines in a protein, the regioselectivity among cysteine residues on the protein surface is an issue to be considered. To elucidate the determinants of cysteine reactivities on protein surfaces, we have investigated the chemical modification of the adenylate kinase A55C/C77S/V169C mutant as an experimental model. Although Cys55 and Cys169 are commonly located on the protein surface, Cys55 showed the ca. 3-6-fold higher reactivity compared to Cys169 in a reaction with a pyrene derivative. By a further conjugation of a phenanthroline derivative into the vacant Cys thiol, fluorescence quenching was attained by a pyrene-phenanthroline interaction that occurred by the conformational change of the protein. The K50A mutation further enhanced the regioselectivity of pyrene conjugation in Cys55, which is attributed to the effects of structural flexibility in the vicinity of Cys55 on its reactivity. To regioselectively conjugate different types of synthetic molecules onto the surface of a protein, perturbation in the local structural flexibility around the conjugation sites will be a useful strategy.

Combined effects of raft length ratio and structural flexibility on power capture performance of an interconnected-two-raft wave energy converter

The power capture performance of an interconnected two-raft wave energy converter (WEC) is investigated in this paper. The equations of motion for the hinged WEC are established using a discrete-module-beam-bending based hydroelasticity method. A mathematical model is then derived for the optimization of power-take-off systems, which is capable of taking into account both different raft length ratios and structural flexibility levels. Based on this mathematical model, the combined effects of raft length ratios and structural flexibility on the power absorption of the hinged two-raft WEC are explored in detail. A small fore-aft raft length ratio is beneficial to power capture in relatively short waves and the performance is further enhanced by the increase of structural flexibility. For relatively long waves, two rafts of equal length may be the optimal condition while the energy absorption is weakened by the structural flexibility. The critical wave number (normalized by the length scale of the rafts) categorizes the effect of structural flexibility on power capture into constructive (larger wave number than the critical value) and destructive (smaller wave number) regions and it is not very sensitive to geometric features of the WEC such as the width of two rafts and the gap between them.

Research on the Control Strategy of Hydraulic Shaking Table Based on the Structural Flexibility

The frequency response characteristics of the hydraulic shaking table show the same as that of a two degree of freedom (DOF) resonance system due to the structural flexibility of the hydraulic shaking table. The hydraulic shaking system induces an anti-resonant peak during the working frequency band, which substantially reduces band width of the shaking table. The frequency response influence factor like mass, stiffness, and damping of the reaction wall are studied in this paper. The feed-forward control strategy is proposed in shaking system, which eliminates the effect of zero points at the anti-resonant peak and poles nearly the imaginary axis, broadens the bandwidth, and improves the control precision of the system. The notch filter is used to reduce the magnitude of resonant peak at the nature frequency of servo valve. The experimental results show that the proposed algorithm properly compensates the effect of structural flexibility and improves the bandwidth of the shaking system.

The influence of intrinsic folding mechanism of an unfolded protein on the coupled folding-binding process during target recognition.

Intrinsically disordered proteins (IDPs) are extensively involved in dynamic signaling processes which require a high association rate and a high dissociation rate for rapid binding/unbinding events and at the same time a sufficient high affinity for specific recognition. Although the coupled folding-binding processes of IDPs have been extensively studied, it is still impossible to predict whether an unfolded protein is suitable for molecular signaling via coupled folding-binding. In this work, we studied the interplay between intrinsic folding mechanisms and coupled folding-binding process for unfolded proteins through molecular dynamics simulations. We first studied the folding process of three representative IDPs with different folded structures, that is, c-Myb, AF9, and E3 rRNase. We found the folding free energy landscapes of IDPs are downhill or show low barriers. To further study the influence of intrinsic folding mechanism on the binding process, we modulated the folding mechanism of barnase via circular permutation and simulated the coupled folding-binding process between unfolded barnase permutant and folded barstar. Although folding of barnase was coupled to target binding, the binding kinetics was significantly affected by the intrinsic folding free energy barrier, where reducing the folding free energy barrier enhances binding rate up to two orders of magnitude. This accelerating effect is different from previous results which reflect the effect of structure flexibility on binding kinetics. Our results suggest that coupling the folding of an unfolded protein with no/low folding free energy barrier with its target binding may provide a way to achieve high specificity and rapid binding/unbinding kinetics simultaneously.

CFD simulation of hemispherical domes: structural flexibility and interference factors

The computational fluid dynamics (CFD) method is widely used today for determining the wind action on structures. Along with the CFD method the wind tunnel experiments are also employed to achieve this purpose. The cost and effort required for a wind tunnel test, however, is much higher than that of the CFD method; therefore, it is beneficial to extend and validate the use of CFD method to various classes and types of structures. This paper firstly compares the results of CFD method with the results of three series of wind tunnel tests available in the literature. Then, numerically the effect of structural flexibility and the neighbourhood of the objects on the wind pressure distribution coefficients are studied. Two and three half spheres are arranged sequentially and transversally. According to the CFD analysis, at a clear distance greater than 2.5 times the diameter of the (obstructing) dome, the wind dynamic interference effects on the reference hemisphere are diminished.

The maximum wave energy conversion by two interconnected floaters: Effects of structural flexibility

The effect of structural flexibility on the maximum wave energy conversion by two interconnected floaters is investigated. For the wave energy converter (WEC), the relative pitch motion of two floaters is converted into electricity by a power take off (PTO) system, which is simplified as a linear damper. The hydrodynamic coefficients of the WEC are calculated based on linear potential flow theory. The coupled effects of structural deformation and hydrodynamic interaction are considered using an approximate approach based on discrete-modules and Euler-Bernoulli beam bending. Then equations of motion of the hinged two-floater WEC with structural deformation considered are established in frequency domain. Based on the motion equations, a mathematical model is proposed for evaluating the maximum wave energy conversion of a hinged two-floater WEC in waves. This mathematical model can be used to calculate the maximum power capture and the corresponding optimum PTO damping for both rigid and flexible two-floater WEC with or without motion constraints. Results show that the structural flexibility has a negative effect on the power capture performance for relatively large wave length but a positive influence for relatively small wave length. The motion constraints lead to a reduction of the captured power for both rigid and flexible WEC.

Reduced-Order Short-Period Model of Flexible Aircraft

A reduced-order short-period model is derived, which allows for representing the effects of structural flexibility on aircraft response to pilot and disturbance inputs on the basis of a minimum set of relevant information on aerodynamic and structural configuration. The model is derived from first principles by means of a Lagrangian approach, featuring vertical (heave) and pitch degrees of freedom, together with deformation variables for flexural deformation of wing and after portion of the fuselage. As a byproduct, an explicit formulation for stability derivatives with respect to deformation variables is derived. Numerical results are reported for a configuration representative of a modern commercial jet aircraft.

Effects of Structural Flexibility on the Kinetics of DNA Y-Junction Assembly and Gelation.

The kinetics of DNA assembly is determined not only by temperature but also by the flexibility of the DNA tiles. In this work, the flexibility effect was studied with a model system of Y-junctions, which contain single-stranded thymine (T) loops in the center. It was demonstrated that the incorporation of a loop with only one thymine prominently improved the assembly rate and tuned the final structure of the assembly, whereas the incorporation of a loop of two thymines exhibited the opposite effect. These observations could be explained by the conformation adjustment rate and the intermotif binding strength. Increasing DNA concentration hindered the conformational adjustment rate of DNA strands, leading to the formation of hydrogels in which the network was connected by ribbons. Therefore, the gel can be treated as a metastable state during the phase transition.

A study on slamming pressure on a flat stiffened plate considering fluid–structure interaction

Normally, the design slamming pressure on the bottom of a semi-submersible-type floating rig is determined in a simple way using the relative speed obtained from an air-gap analysis. However, few studies have taken a thorough, robust, and deep-background approach to the estimation of design pressure. To investigate the slamming pressure on the bottom of a semi-submersible rig, a simplified deformable stiffened plate of a zero-degree deadrise angle is simulated using the nonlinear FEM software LS-DYNA, which can take the influence of fluid–structure interaction (FSI) into account. Various parametric studies are carried out to examine the effects of structural flexibility, coupling stiffness, mesh size, velocity, stiffener size, and air cushion. The pressure response on the plate by the coupling of fluid and structure is studied and the FSI effect of each parameter is discussed. Then, equivalent transient and static loads that result in the same maximum or permanent deformation as FSI are evaluated for design purposes through a series of parametric studies.

1P1-R10 蝶の羽ばたき飛翔における構造柔軟性による受動的安定性

1P1-R10 蝶の羽ばたき飛翔における構造柔軟性による受動的安定性