scholarly journals A Parametrization-Invariant Fourier Approach to Planar Linkage Synthesis for Path Generation

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Xiangyun Li ◽  
Peng Chen
Keyword(s):  
Design Space ◽  
Fourier Descriptors ◽  
Path Generation ◽  
Arc Length ◽  
Efficient Synthesis ◽  
Practical Applications ◽  
Classic Problem ◽  
Fourier Theory ◽  
Planar Linkages ◽  
Synthesis Approach

This paper deals with the classic problem of the synthesis of planar linkages for path generation. Based on the Fourier theory, the task curve and the synthesized four-bar coupler curve are regarded as the same curve if their Fourier descriptors match. Using Fourier analysis, a curve must be given as a function of time, termed a parametrization. In practical applications, different parametrizations can be associated with the same task and coupler curve, respectively; however, these parametrizations are Fourier analyzed to different Fourier descriptors, thus resulting in the mismatch of the task and coupler curve. In this paper, we present a parametrization-invariant method to eliminate the influence of parametrization on the values of Fourier descriptors by unifying given parametrizations to the arc length parametrization; meanwhile, a new design space decoupling scheme is introduced to separate the shape, size, orientation, and location matching of the task and four-bar curve, which leads naturally to an efficient synthesis approach.

Optimal Synthesis of Mechanisms for Path Generation Using Fourier Descriptors and Global Search Methods

1997 ◽  
Vol 119 (4) ◽  
pp. 504-510 ◽  
Author(s):  
Irfan Ullah ◽  
Sridhar Kota
Keyword(s):  
Objective Function ◽  
Design Space ◽  
Initial Guess ◽  
Global Search ◽  
Search Method ◽  
Fourier Descriptors ◽  
Path Generation ◽  
Local Optima ◽  
Structural Error ◽  
Synthesis Of Mechanisms

Generally, success in synthesis of mechanisms for path generation is limited to finding a reasonable local optima at best in spite of a very good initial guess. The most widely used Structural Error objective function is not effective in leading to practical solutions as it misrepresents the nature of the design problem by requiring the shape, size, orientation and position of the coupler curve to be optimized all at once. In this paper, we present an effective objective function based on Fourier descriptors that evaluates only the shape differences between two curves. This function is first minimized using a stochastic global search method derived from simulated annealing followed by Powell’s method. The size, orientation and position of the desired curve are addressed in a later stage by determining analogous points on the desired and candidate curves. In spite of highly non-linear mechanisms design space, our method discovers near-global and practical solutions consistently without requiring any initial guess.

Solvent-free and efficient synthesis of bicyclic 2-pyridone derivatives for endoplasmic reticulum imaging

2021 ◽  
Author(s):  
Xiaoyun Ran ◽  
Qian Zhou ◽  
Jin Zhang ◽  
Shanqiang Wang ◽  
Gui Wang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Citric Acid ◽  
Core Structure ◽  
Solvent Free ◽  
Efficient Synthesis ◽  
The Core ◽  
Catalyst Free ◽  
Synthesis Approach ◽  
Ethylenediamine Derivatives

Started from citric acid (CA) and ethylenediamine derivatives, a solvent-free, catalyst-free and highly yield synthesis approach for bicyclic 2-pyridones was presented. Continuing to modify the core structure, a series of...

Optimal Design of a 2-UPR-RPU Parallel Manipulator

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Feibo Wang ◽  
Qiaohong Chen ◽  
Qinchuan Li
Keyword(s):  
Optimal Design ◽  
Parallel Manipulator ◽  
Design Space ◽  
Parameter Design ◽  
Optimal Parameters ◽  
Force Transmission ◽  
Universal Joint ◽  
Practical Applications ◽  
Optimum Region ◽  
Dimensional Optimization

This paper investigates dimensional optimization of a 2-UPR-RPU parallel manipulator (where U is a universal joint, P a prismatic pair, and R a revolute pair). First, the kinematics and screws of the mechanism are analyzed. Then, three indices developed from motion/force transmission are proposed to evaluate the performance of the 2-UPR-RPU parallel manipulator. Based on the performance atlases obtained, a set of optimal parameters are selected from the optimum region within the parameter design space. Finally, the optimized parameters are determined for practical applications.

A New Protocol for Secure Distributed Multiplication of Two Polynomial Shared Values

2014 ◽  
Vol 1042 ◽  
pp. 110-116
Author(s):  
Xiang Ning Hao ◽  
Xue Min Wang ◽  
Li Qiong Deng
Keyword(s):  
Secret Sharing ◽  
Shared Values ◽  
Secret Sharing Scheme ◽  
Threshold Secret Sharing ◽  
Practical Applications ◽  
Classic Problem ◽  
Sharing Scheme ◽  
Better Than

In view of practical applications, it is a high priority to optimize the efficiency of methods for secure multi-party computations. A classic problem is described as following: there are two secrets, α and β, shared among n players using Shamir (t+1,n)-threshold secret sharing scheme, and how to make their product αβshared among n players using the same way. The protocol of Gennaro, Rabin and Rabin (1998) is a well known and efficient protocol for this purpose. It requires one round of communication and O(n2klog2n+nk2) bit-operations per player, where k is the bit size of the computing field and n is the number of players. In a previous paper (2007), the author presented a modification of this protocol, which reduced its complexity toOn2k+nk2. In 2009, Peter Lory reduced its complexity to On2k. A new protocol is presented in our paper, which reduces this complexity further to Onklog2k. It is better than Gennaro protocol unconditionally. And as to Peter Lory protocol, the reduction is profitable in situation where log2k is smaller than n.

A Flexible Discrete Building Block Synthesis Approach As Basis for the Design of Planar Linkages

2017 ◽  
Author(s):  
Simon Laudahn ◽  
Franz Irlinger ◽  
Kassim Abdul-Sater
Keyword(s):  
Building Block ◽  
Integrated Design ◽  
Optimal Solution ◽  
Design Tool ◽  
Grid Search ◽  
Approximate Synthesis ◽  
Synthesis Procedure ◽  
Block Based ◽  
Planar Linkages ◽  
Synthesis Approach

In this paper we present a computational approximate synthesis procedure for the planar RR chain. Our approach is based on a grid search and takes an arbitrary amount of user-defined task positions for the two outer bodies of the chain and restrictions for both joints into account. The result of this synthesis approach is not only one optimal solution, but a list of several possible solutions which are ranked according to their performance. The approach aims at being used in building block-based synthesis procedures of more complex linkages. The method shall later be included into a CAD-integrated design tool for planar linkages.

scholarly journals Centimetric-Sized Chromium (III) Oxide Object Synthesized by Means of the Carbon Template Replication

Ceramics ◽  
2020 ◽  
Vol 3 (1) ◽  
pp. 92-100
Author(s):  
Pierre GIBOT
Keyword(s):  
Material Surface ◽  
Efficient Synthesis ◽  
X Ray Diffraction ◽  
Replica Technique ◽  
X Ray ◽  
Ceramic Oxide ◽  
Carbon Template ◽  
Synthesis Approach ◽  
Scanning Electron ◽  
Salt Coating

A simple, efficient synthesis approach for designing large ceramic pieces, herein termed chromium (III) oxide (Cr2O3) material, is provided. The process can be called the replica technique, or replication. The elaboration of a material with a unique morphology is a result of a ceramic salt coating that has been previously dissolved in ethylene glycol as the solvent; this process is performed on a carbon material surface that is selected as a template. Here, the carbon template was carbon fiber. After a heat treatment to convert the ceramic precursor to the corresponding ceramic oxide followed by the removal of the template, hollow ceramic oxide wires were obtained. The resulting material was characterized by X-ray diffraction, Raman and Fourier transform infrared spectroscopies, and scanning electron microscopy. The material exhibited a multiscale architecture, assembling nanosized nodules to form micron-sized tubes that assemble themselves into a centimetric structure. Objects with such tailored architectures can be used in a large variety of applications in fields as diverse as pyrotechnics, adsorption, and catalysis.

A New Method for Completely Force Balancing Simple Linkages

1969 ◽  
Vol 91 (1) ◽  
pp. 21-26 ◽  
Author(s):  
R. S. Berkof ◽  
G. G. Lowen
Keyword(s):  
Center Of Mass ◽  
Time Dependent ◽  
New Method ◽  
Practical Applications ◽  
Mass Distributions ◽  
Linearly Independent ◽  
Planar Linkages

A new method, herein referred to as the “Method of Linearly Independent Vectors,” is shown to permit the complete force balancing of certain planar linkages. This method consists of writing the equation describing the position of the total mechanism center of mass in such a way that the coefficients of the time-dependent terms may be set equal to zero. In this way, the total center of mass can be made stationary, and the shaking force vanishes. Derivations as well as practical applications are shown for four-bar and six-bar linkages with arbitrary link mass distributions.

Geometry Optimization of Flexure System Topologies Using the Boundary Learning Optimization Tool (BLOT)

2017 ◽  
Author(s):  
Ali Hatamizadeh ◽  
Yuanping Song ◽  
Jonathan B. Hopkins
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Efficient Algorithm ◽  
Design Space ◽  
Geometry Optimization ◽  
Computational Tool ◽  
Constituent Material ◽  
Constraint Topologies ◽  
Synthesis Approach

In this paper, we introduce a new computational tool called the Boundary Learning Optimization Tool (BLOT) that rapidly identifies the boundary of the performance capabilities achieved by a general flexure topology if its geometric parameters are allowed to vary from their smallest allowable feature sizes to the largest geometrically compatible feature sizes for a given constituent material. The boundaries generated by the BLOT fully define a flexure topology’s design space and allow designers to visually identify which geometric versions of their synthesized topology best achieve a desired combination of performance capabilities. The BLOT was created as a complementary tool to the Freedom And Constraint Topologies (FACT) synthesis approach in that the BLOT is intended to optimize the geometry of the flexure topologies synthesized using the FACT approach. The BLOT trains artificial neural networks to create sufficiently accurate models of parameterized flexure topologies using the fewest number of design instantiations and their corresponding numerically generated performance solutions. These models are then used by an efficient algorithm to plot the desired topology’s performance boundary. A FACT-synthesized flexure topology is optimized using the BLOT as a case study.

Design of Crashworthy Structures With Controlled Energy Absorption in the Hybrid Cellular Automaton Framework

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Punit Bandi ◽  
James P. Schmiedeler ◽  
Andrés Tovar
Keyword(s):  
Energy Absorption ◽  
Design Space ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Mechanism Synthesis ◽  
Load Paths ◽  
Fully Stressed Design ◽  
Novel Method ◽  
The Given ◽  
Synthesis Approach

This work presents a novel method for designing crashworthy structures with controlled energy absorption based on the use of compliant mechanisms. This method helps in introducing flexibility at desired locations within the structure, which in turn reduces the peak force at the expense of a reasonable increase in intrusion. For this purpose, the given design domain is divided into two subdomains: flexible (FSD) and stiff (SSD) subdomains. The design in the flexible subdomain is governed by the compliant mechanism synthesis approach for which output ports are defined at the interface between the two subdomains. These output ports aid in defining potential load paths and help the user make better use of a given design space. The design in the stiff subdomain is governed by the principle of a fully stressed design for which material is distributed to achieve uniform energy distribution within the design space. Together, FSD and SSD provide for a combination of flexibility and stiffness in the structure, which is desirable for most crash applications.

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