Search results

The purpose of this paper is to propose an efficient finite element formulation for nonlinear analysis of clustered tensegrity that consists of classical cables, clustered cables and bars.

The derivation of the finite element formulation is based on the co-rotational approach, which decomposes a geometrically nonlinear deformation into a large rigid body motion and a small-strain deformation. A tangent stiffness matrix of a clustered cable is proposed and the Newton-Raphson scheme is employed to solve the nonlinear equation.

The derived tangent stiffness matrix, including an additional stiffness terms that describes the slide effect of pulleys, can regress to the stiffness matrix of a classical cable, which is convenient for the implementation of finite element procedure. Two typical numerical examples show that the proposed formulation is accurate and requires less iteration than the force density method.

The co-rotational formulation of a clustered cable is originally proposed, although some mature methods, such as the TL, Force Density and Dynamic Relaxation method, have been applied to nonlinear analysis of clustered tensegrity. The proposed co-rotational formulation proved efficient.

This paper is contributed to find the minimal mass prismatic tensegrity structures.

In the stable state of the structure with any given external force, the internal forces of the structure members are taken as the critical force to calculate the cross-sectional area, and the total mass of the structure can be obtained. Firstly, the mathematical model of prismatic tensegrity was built. Secondly, the stability of the tensegrity was analyzed based on the force equilibrium of one node, the force density relationship of elements was obtained. The deformation of p-bar tensegrity prism unit was studied with the same mass. The force of the structure under external force was analyzed.

(1) The length of bar and the structural radius are almost invariant, and the mechanical properties of 3-bar tensegrity prism is more outstanding; (2) theoretically, the mass of the structure is minimal while the projection of bar passes the center of the circle. Under the circumstances, the force of diagonal cable is 0 N, the vertical force component of bar cancels the axial external force.

(1) By analyzing the deformation of p-bar tensegrity prism with the same mass, the length of bar and the structural radius are proved be almost invariant and the mechanical properties of 3-bar tensegrity prism is more outstanding; (2) theoretically, the mass of the structure is minimal while the projection of bar passes the center of the circle. Under the circumstances, the force of diagonal cable is 0 N, the vertical force component of bar cancels the axial external force.

The purpose of this paper is to propose an accurate and efficient numerical method for determining the dynamic responses of a tensegrity structure consisting of bars, which can work under both compression and tension, and cables, which cannot work under compression.

An accurate time-domain solution is obtained by using the precise integration method when there is no cable slackening or tightening, and the Newton–Raphson scheme is used to determine the time at which the cables tighten or slacken.

Responses of a tensegrity structure under harmonic excitations are given to demonstrate the efficiency and accuracy of the proposed method. The validation shows that the proposed method has higher accuracy and computational efficiency than the Runge–Kutta method. Because the cables of the tensegrity structure might be tense or slack, its dynamic behaviors will exhibit stable periodicity, multi-periodicity, quasi-periodicity and chaos under different amplitudes and frequencies of excitation.

The steady state response of a tensegrity structure can be obtained efficiently and accurately by the proposed method. Based on bifurcation theory, the Poincaré section and phase space trajectory, multi-periodic vibration, quasi-periodic vibration and chaotic vibration of the tensegrity structures are predicted accurately.

Solid freeform fabrication is particularly suitable for fabricating customized parts, but it has not been used for fabricating deployable structures that can be stored in a compact configuration and deployed quickly and easily in the field. The purpose of this paper is to present a methodology for deploying flexible, freeform structure with lattice skins as the deploying mechanism.

A ground structure‐based topology optimization procedure is utilized, with a penalization scheme that encourages convergence to sets of thick lattice elements that are manufacturable and extremely thin lattice elements that are removed from the final structure.

A deployable wing is designed for a miniature unmanned aerial vehicle. A physical prototype of the optimal configuration is fabricated with selective laser sintering and compared with the virtual prototype. The proposed methodology results in a 78 percent improvement in deviations from the intended surface profile of the deployed part.

The results presented in the paper provide proof‐of‐concept for the use of lattice skins as a deployment mechanism. A topology optimization framework is also provided for designing these lattice skins. Potential applications include portable, camouflaged shelters and deployable aerial vehicles.

When designing a performance involving people and mobile robots, the required functions and shape of the robot must be considered. However, it can be difficult to account for all of the requirements. The purpose of this paper is to discuss a mobile robot in the shape of a ball that is used in theatrical performances.

The paper proposes a mobile robot that can give the audience the optical illusion of the unique movements of a sphere by mounting a spherical light-emitting diode (LED) display on a high-agility wheeled robot.

It was found that movements that are difficult to implement with existing mechanisms can nonetheless be visualized through the use of light.

The paper proposes the concept of using pseudo-physical movements in performances with robots. The authors built a robot that visually reproduces the movements of a rolling sphere and is capable of faster movements and easier position estimations in comparison with previous spherical robots.

Numerical models are being increasingly relied upon to evaluate wind turbine performance by simulating phenomena that are infeasible to measure experimentally. These numerical models, however, require a large number of input parameters that often need to be calibrated against available experiments. Owing to the unavoidable scarcity of experiments and inherent uncertainties in measurements, this calibration process may yield non-unique solutions, i.e. multiple sets of parameters may reproduce the available experiments with similar fidelity. The purpose of this paper is to study the trade-off between fidelity to measurements and the robustness of this fidelity to uncertainty in calibrated input parameters.

Here, fidelity is defined as the ability of the model to reproduce measurements and robustness is defined as the allowable variation in the input parameters with which the model maintains a predefined level of threshold fidelity. These two vital attributes of model predictiveness are evaluated in the development of a simplified finite element beam model of the CX-100 wind turbine blade.

Findings of this study show that calibrating the input parameters of a numerical model with the sole objective of improving fidelity to available measurements degrades the robustness of model predictions at both tested and untested settings. A more optimal model may be obtained by calibration methods considering both fidelity and robustness. Multi-criteria Decision Making further confirms the conclusion that the optimal model performance is achieved by maintaining a balance between fidelity and robustness during calibration.

Current methods for model calibration focus solely on fidelity while the authors focus on the trade-off between fidelity and robustness.

The purpose of this paper is to provide a close, detailed analysis of the frequency, nature, and depth of visible use of two of Foucault’s classic early works, The Archaeology of Knowledge and The Order of Things, by library, and information science/studies (LIS) scholars.

The study involved conducting extensive full-text searches in a large number of electronically available LIS journal databases to find citations of Foucault’s works, then examining each citing article and each individual citation to evaluate the nature and depth of each use.

Contrary to initial expectations, the works in question are relatively little used by LIS scholars in journal articles, and where they are used, such use is often only vague, brief, or in passing. In short, works traditionally seen as central and foundational to discourse analysis appear relatively little in discussions of discourse.

The study was limited to a certain batch of LIS journal articles that are electronically available in full text at UCLA, where the study was conducted. The results potentially could change by focussing on a fuller or different collection of journals or on non-journal literature. More sophisticated bibliometric techniques could reveal different relative performance among journals. Other research approaches, such as discourse analysis, social network analysis, or scholar interviews, might reveal patterns of use and influence that are not visible in the journal literature.

This study’s intensive, in-depth study of quality as well as quantity of citations challenges some existing assumptions regarding citation analysis and the sociology of citation practices, plus illuminating Foucault scholarship.

To provide a close, detailed analysis of the frequency, nature, and depth of visible use of Michel Foucault's works by library and information science/studies (LIS) scholars.

The study conducted extensive full-text searches in a large number of electronically available LIS journal databases to find citations of Foucault's works, then examined each cited article to evaluate the nature and depth of use.

Most uses of Foucault are brief or in passing. In-depth explorations of Foucault's works are comparatively rare and relatively little-used by other LIS scholars. Yet the relatively brief uses of Foucault encompass a wide array of different topics spread across a wide spectrum of LIS journal literature.

The study was limited to articles from particular relatively prominent LIS journals. Results might vary if different journals or non-journal literature were studied. More sophisticated bibliometric techniques might reveal different relative performance among journals and might better test, confirm, or reject various patterns and relationships found here. Other research approaches, such as discourse analysis, social network analysis, or scholar interviews, might reveal patterns of use and influence not visible in this literature sample.

This intensive study of both quality and quantity of citations may challenge some existing assumptions regarding citation analysis, plus illuminating Foucault scholarship. It also indicates possible problems for future application of artificial intelligence (AI) approaches to similar depth-of-use studies.

In order to more accurately predict the dynamics of the e-commerce market and increase the comprehensive value of the circular e-commerce industry, proposes to use Grey system theory to analyze the circular economy of the e-commerce market.

Construct a Grey system theory model, analyze the big data of e-commerce and circular economy of the e-commerce market and predict the development potential of China's e-commerce market.

The results show that the Grey system theory model can play an important role in the data analysis of circular economy of the e-commerce market.

Use Grey model to analyze e-commerce data, discover e-commerce market rules and problems and then optimize e-commerce market.