scholarly journals Design and analysis of symmetric and compact 2R1T (in-plane 3-DOC) flexure parallel mechanisms

2017 ◽  
Vol 8 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Guangbo Hao
Keyword(s):  
Analytical Modelling ◽  
Analytical Models ◽  
Parallel Mechanisms ◽  
Primary Motion ◽  
Stiffness Reduction

Abstract. Symmetry is very necessary in flexure mechanisms, which can eliminate parasitic motions, avoid buckling, and minimize thermal and manufacturing sensitivity. This paper proposes two symmetric and compact flexure designs, in-plane 3-DOC (degree of constraint) mechanisms, which are composed of 4 and 6 identical wire beams, respectively. Compared to traditional leaf-beam-based designs, the two present designs have lower stiffness in the primary motion directions, and have smaller stiffness reduction in the parasitic directions. Analytical modelling is conducted to derive the symbolic compliance equations, enabling quick analysis and comparisons of compliances of the two mechanisms. A prototype has been tested statically to compare with analytical models.

scholarly journals Assessing the Accuracy of Performance Modelling in Software Defined Networks

2021 ◽  
Author(s):  
◽  
Jordan Ansell
Keyword(s):  
Experimental Measurement ◽  
Network Models ◽  
Analytical Modelling ◽  
Analytical Models ◽  
Queueing Models ◽  
Software Defined Network ◽  
Software Defined Networks ◽  
Performance Modelling ◽  
Experimental Performance ◽  
Performance Results

<p>Analytical modelling and experimental measurement can are used to evaluate the performance of a network. Models provide insight and measurement provides realism.  For software defined networks (SDN) it is unknown how well the existing queueing models represent the performance of a real SDN network. This leads to uncertainty between what can be predicted and the actual behaviour of a software defined network.  This work investigates the accuracy of software defined network queueing models. This is done through comparing the performance results of analytical models to experimental performance results.  The outcome of this is an understanding of how reliable the existing queueing models are and areas where the queueing models can be improved.</p>

Review of the Role of Analytical Modelling Methods in Riverbank Filtration System

2014 ◽  
Vol 71 (1) ◽  
Author(s):  
Shaymaa Mustafa ◽  
Arifah Bahar ◽  
Zainal Abdul Aziz ◽  
Saim Suratman
Keyword(s):  
Point Of View ◽  
Analytical Modelling ◽  
Analytical Models ◽  
Riverbank Filtration ◽  
Stream Depletion ◽  
Filtration System ◽  
Depletion Rate ◽  
Contaminants Transport ◽  
Modelling Methods

Riverbank filtration (RBF) technology is applied in several countries around the world as one of the main sources of drinking water supply both from quantitative and qualitative point of view. Consequently, several analytical modelling methods, mostly based on the transformation techniques, are developed in literature to describe different processes which occur in RBF system. An extensive overview of these analytical methods, their uses and limitations are discussed. The review disclosed that most analytical models usually are concerned in evaluating stream depletion rate rather than contaminants transport especially the transportation of pesticides and pathogens. Laplace and Fourier methods are more popular methods used by researchers to solve the system of partial differential equation that developed to simulate the RBF problem.

When Should a Ski Resort Make Snow?

2011 ◽  
Vol 17 (6) ◽  
pp. 1219-1234 ◽  
Author(s):  
Kevin R. Caskey
Keyword(s):  
Analytical Methods ◽  
Actual Practice ◽  
Analytical Modelling ◽  
Analytical Models ◽  
Strategic Issues ◽  
Ski Resort ◽  
Ski Resorts

Snow-making is an expensive operation for a ski resort. However, many resorts would be unable to operate without man-made snow. Deciding when to make snow involves several uncertain factors, as well as significant strategic issues. First, the author describes the framework for this decision. Next, he proposes analytical modelling. Finally, he compares the proposed models to actual practice at several resorts and proposes further research. The author finds that actual practice at most ski resorts does not involve formal analytical methods. While the resorts consider many of the factors included in the models, the decision is generally not modelled explicitly. The use of the proposed analytical models could lead to a better understanding of the factors involved in the snow-making decision, and thus to better service at a reduced cost.

Nonlinear Analytical Modeling and Characteristic Analysis of a Class of Compound Multibeam Parallelogram Mechanisms

2015 ◽  
Vol 7 (4) ◽  
Author(s):  
Guangbo Hao ◽  
Haiyang Li
Keyword(s):  
Experimental Testing ◽  
Slenderness Ratio ◽  
Analytical Models ◽  
Stiffness Ratio ◽  
Motion Model ◽  
Characteristic Analysis ◽  
Diagram Method ◽  
Primary Motion ◽  
Parasitic Motion ◽  
Fea Model

This paper deals with nonlinear analytical models of a class of compound multibeam parallelogram mechanisms (CMPMs) along with the static characteristic analysis. The CMPM is composed of multiple compound basic parallelogram mechanisms (CBPMs) in an embedded parallel arrangement. First, nonlinear analytical models for the CBPM are derived using the free-body diagram method through appropriate approximation strategies. The nonlinear analytical models of the CMPM are then derived based on the modeling results of the CBPM. Nonlinear finite element analysis (FEA) comparisons, experimental testing, and detailed stiffness analysis for the CBPM are finally carried out. It is shown that the analytical primary motion model agrees with both the FEA model and the testing result very well but the analytical parasitic motion model deviates from the FEA model over the large primary motion/force. It is also shown from the analytical characteristic analysis that the primary translational stiffness increases with the primary motion but the parasitic motion stiffness decreases with the primary motion, and the stiffness ratio of the parasitic motion stiffness to the primary translation stiffness also decreases with the primary motion. It is found that the larger the beam slenderness ratio is, the larger the stiffness or stiffness ratio is, and the more apparent the change of the stiffness or stiffness ratio is. The varied stiffness ratio indicates the mobility change of the CBPM.

scholarly journals Assessing the Accuracy of Performance Modelling in Software Defined Networks

2021 ◽  
Author(s):  
◽  
Jordan Ansell
Keyword(s):  
Experimental Measurement ◽  
Network Models ◽  
Analytical Modelling ◽  
Analytical Models ◽  
Queueing Models ◽  
Software Defined Network ◽  
Software Defined Networks ◽  
Performance Modelling ◽  
Experimental Performance ◽  
Performance Results

<p>Analytical modelling and experimental measurement can are used to evaluate the performance of a network. Models provide insight and measurement provides realism.  For software defined networks (SDN) it is unknown how well the existing queueing models represent the performance of a real SDN network. This leads to uncertainty between what can be predicted and the actual behaviour of a software defined network.  This work investigates the accuracy of software defined network queueing models. This is done through comparing the performance results of analytical models to experimental performance results.  The outcome of this is an understanding of how reliable the existing queueing models are and areas where the queueing models can be improved.</p>

Design of 3-legged XYZ compliant parallel manipulators with minimised parasitic rotations

Robotica ◽  
2014 ◽  
Vol 33 (4) ◽  
pp. 787-806 ◽  
Author(s):  
Guangbo Hao ◽  
Haiyang Li
Keyword(s):  
Finite Element Analysis ◽  
Large Range ◽  
Experimental Testing ◽  
Parallel Manipulators ◽  
Analytical Models ◽  
Parallel Mechanisms ◽  
Characteristic Analysis ◽  
Electric Discharge Machining ◽  
Element Analysis ◽  
Manufacturing Technologies

SUMMARYThis paper deals with the design of 3-legged distributed-compliance XYZ compliant parallel manipulators (CPMs) with minimised parasitic rotations, based on the kinematically decoupled 3-PPPRR (P: prismatic joint, and R: revolute joint) and 3-PPPR translational parallel mechanisms (TPMs). The designs are firstly proposed using the kinematic substitution approach, with the help of the stiffness center (SC) overlapping based approach. This is done by an appropriate embedded arrangement so that all of the SCs associated with the passive compliant modules overlap at the point where all of the input forces applied at the input stages intersect. Kinematostatic modelling and characteristic analysis are then carried out for the proposed large-range 3-PPPRR XYZ CPM with overlapping SCs. The results from finite element analysis (FEA) are compared to the characteristics found for the developed analytical models, as are experimental testing results (primary motion) from the prototyped 3-PPPRR XYZ CPM with overlapping SCs. Finally, issues on large-range motion and dynamics of such designs are discussed, as are possible improvements of the actuated compliant P joint. It is shown that the potential merits of the designs presented here include a) minimised parasitic rotations by only using three identical compliant legs; b) compact configurations and small size due to the use of embedded designs; c) approximately kinematostatically decoupled designs capable of easy controls; and d) monolithic fabrication for each leg using existing planar manufacturing technologies such as electric discharge machining (EDM).

Design and Modelling of Spatial Compliant Parallel Mechanisms for Large Range of Translation

2010 ◽  
Author(s):  
Guangbo Hao ◽  
Xianwen Kong ◽  
Qiaoling Meng
Keyword(s):  
Large Range ◽  
Building Blocks ◽  
Analytical Models ◽  
Parallel Mechanisms ◽  
Beam Length ◽  
Straightforward Manner ◽  
Compliance Matrix ◽  
Normalization Strategy ◽  
Compliant Parallel Mechanism ◽  
Linear Actuators

A new distributed-compliance module, which can be used as a building block, is proposed at first. A novel 3-DOF compliant parallel mechanism (CPM) and its improved configuration for large range of translation are then proposed using the new building blocks. The analytical models of the spatial modules and 3-DOF translational CPMs are then presented and analyzed. The proposed improved 3-DOF translational CPM has the following merits: (1) It is approximately decoupled and has a workspace of 0.1Lmm×0.1Lmm×0.1Lmm (L: the beam length in the module) with constrained parasitic error, maximal actuation isolation and minimal lost motion. (2) Its configuration is simple and compact, and it is actuated by three linear actuators directly. (3) The normalization strategy not only simplifies the representation and derivation of the equations, but also makes the compliance matrix reflect the displacement associated with each degree of freedom in a straightforward manner. The proposed analytical model for the improved 3-DOF CPM has been verified using FEA.

Understanding Government Survival: Empirical Exploration or Analytical Models?

1999 ◽  
Vol 29 (2) ◽  
pp. 395-401 ◽  
Author(s):  
MICHAEL LAVER ◽  
KENNETH A. SHEPSLE
Keyword(s):  
Review Essay ◽  
Analytical Modelling ◽  
Analytical Models ◽  
Parliamentary Democracy ◽  
Simulation Technology ◽  
Government Formation

We should begin our reply to Paul Warwick by stating how very flattered we are by the diligent attention that he has given to our work on government formation. In particular, we are delighted that he has taken up and applied the simulation technology that we suggested as a way to explore cabinet stability, a matter on which we were beginning to feel like voices wailing in the wilderness.This is not the place to bore readers of the Journal with detailed points of issue between us, of which there are obviously many. We want here to concentrate upon some larger issues provoked by Warwick's critique. These involve a debate on cabinet stability and duration between a school of thought, in Warwick's corner, that is essentially empiricist in its outlook and a school of thought, in ours, that takes analytical modelling as being more fundamental. This is a theme touched upon by Kaare Strom in his recent review essay on parliamentary democracy.

scholarly journals Mathematical modeling of auxetic systems: bridging the gap between analytical models and observation

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
James N. Grima-Cornish ◽  
Joseph N. Grima ◽  
Daphne Attard
Keyword(s):  
Mathematical Modeling ◽  
Poisson’S Ratio ◽  
Scientific Literature ◽  
Applied Strain ◽  
Analytical Modelling ◽  
Poisson's Ratio ◽  
Analytical Models ◽  
Transverse Strain

AbstractThe Poisson’s ratio, a property which quantifies the changes in thickness when a material is stretched and compressed, can be determined as the negative of the transverse strain over the applied strain. In the scientific literature, there are various ways how strain may be defined and the actual definition used could result in a different Poisson’s ratio being computed. This paper will look in more detail at this by comparing the more commonly used forms of strain and the Poisson’s ratio that is computable from them. More specifically, an attempt is made to assess through examples on the usefulness of the various formulations to properly describe what can actually be observed, thus providing a clearer picture of which form of Poisson’s ratio should be used in analytical modelling.

scholarly journals Analysis of Vibration Reduction by Damping Using Simple Analytical Modelling

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Goran Pavić
Keyword(s):  
Comparative Study ◽  
Vibration Reduction ◽  
Substantial Reduction ◽  
Analytical Modelling ◽  
Analytical Models ◽  
Vibration Absorbers ◽  
Vibration Level ◽  
Structural Damping ◽  
Damping Effect ◽  
Selection Of

The performance of different solutions to global vibration reduction using external damping is discussed. The solutions are either uneven distribution of structural damping or use of vibration absorbers. To this end, a comparative study is carried out, built on simple analytical models. It is shown that a well-chosen solution can produce a substantial reduction of global vibration level. It is further shown that the overall damping effect critically depends on the mutual interaction between the applied damping device and the damped structure. Qualitative guidelines are provided about the selection of appropriate parameters that affect damping performance.

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