On the Branch Formation of Linkages

2009 ◽  
Author(s):  
Kwun-Lon Ting ◽  
Changyu Xue ◽  
Jun Wang ◽  
Kenneth R. Currie
Keyword(s):  
Theoretical Background ◽  
Loop System ◽  
Double Loop ◽  
Branch Points ◽  
Mobility Analysis ◽  
Branch Formation ◽  
Spatial Linkages ◽  
Group 2 ◽  
Fundamental Equations

A spatial linkage with the displacement governed by two fundamental equations can be regarded as a virtual double loop system. The mobility of the linkage is affected by the mobility of each individual “loop” as well as the interaction between the loops. The current use of branch points for branch identification is limited to linkages with simple topology, such as Stephenson-type linkages, which are simplified versions of group 2 mechanisms. However, in a general spatial group 2 linkage, both the fundamental equations are equivalent to virtual five-bar loops. Branch points in Stephenson-type linkages should be generalized to explain and define the interaction between two virtual five-bar loops. The concept of generalized branch points offers the explanation of how branches are formed in spatial group 2 linkages. This paper presents the theoretical background for the mobility analysis of complex spatial linkages.

On the Mobility of Spatial Group 2 Mechanisms

2009 ◽  
Author(s):  
Kwun-Lon Ting ◽  
Changyu Xue ◽  
Jun Wang ◽  
Kenneth R. Currie
Keyword(s):  
Branch Points ◽  
Mobility Analysis ◽  
Spatial Linkages ◽  
Group 2 ◽  
Fundamental Equations

Spatial linkages are classified into four groups according to the number of fundamental equations or virtual loops that govern linkage displacement. The number of virtual loops represents the complexity of a spatial linkage as that of planar or spherical multiloop linkages. The concept of generalized branch points offers the explanation of how branches are formed in spatial group 2 linkages. In this paper, the mobility analysis is carried out based on the similarity of the mobility features rather than the specific or individual linkage structure. A branch rectification scheme is presented and demonstrated with examples.

scholarly journals Research on design method of double-loop electric servo loading system with high-frequency band based on H∞ control strategy

2020 ◽  
pp. 002029402096213
Author(s):  
Yang Shui ◽  
Jianli Wei ◽  
Jie Yan
Keyword(s):  
Frequency Band ◽  
Loop System ◽  
Aerodynamic Load ◽  
Double Loop ◽  
Hardware In The Loop ◽  
Load Spectrum ◽  
Electric Loading ◽  
Technical Requirements ◽  
Loading System ◽  
High Dynamic

In the hardware-in-the-loop simulation, the goal of electric loading is to realize the accurate tracking of the torque signal and test the performance of the aircraft actuator system. For some high dynamic aircraft, it is necessary to reduce the influence of the surplus torque to increase the system frequency band. This paper introduces a new electric loading system which adopts a double-loop servo motor as the torque loading mechanism. It applies two loops to track the position of the rudder and the aerodynamic load spectrum respectively. For the purpose of reducing the disturbance between two loops of the scheme, a two-DOF H∞ robust controller is designed, which improves the robustness of the system effectively. The simulation results show that the new system increases the upper limit of 25 Hz frequency band of the traditional single-loop system with PID control to the maximum of 40 Hz. The double-loop system thereby meets the technical requirements of the hardware-in-the-loop simulation experiment for high dynamic aircrafts.

On the Input Joint Rotation Space and Mobility of Linkages

2008 ◽  
Vol 130 (9) ◽  
Author(s):  
Kwun-Lon Ting
Keyword(s):  
Visualization Tool ◽  
Mobility Analysis ◽  
Joint Rotation ◽  
Single Loop ◽  
Spatial Linkages ◽  
One To One ◽  
Spherical Linkages ◽  
Virtual Loop

This paper presents the concept and application of input joint rotation space of linkages and offers updates on the N-bar rotatability laws. A thorough discussion on the joint rotation space of single-loop planar five-bar linkages is first presented. The concept is then extended to spherical linkages and the generalization to N-bar linkages is discussed. It offers a visualization tool for the input joint rotatability and fills up a void in the N-bar rotatability laws regarding the coordination among multiple inputs. It explains the formation of branches and how to establish a one-to-one correspondence between the inputs and the linkage configurations. The applications to multiloop linkages and spatial linkages are highlighted with Stephenson six-bar linkages, geared linkages, and spatial RCRCR mechanisms. These examples exhibit simplicity and benefits of the proposed concept to the mobility analysis of diversified mechanisms. The concept of virtual loop in spatial linkages is proposed and demonstrated with simple RCRCR and Stephenson six-bar mechanisms.

scholarly journals Pulmonary neuroendocrine cells amplify allergic asthma responses

Science ◽  
2018 ◽  
Vol 360 (6393) ◽  
pp. eaan8546 ◽  
Author(s):  
Pengfei Sui ◽  
Darin L. Wiesner ◽  
Jinhao Xu ◽  
Yan Zhang ◽  
Jinwoo Lee ◽  
...  
Keyword(s):  
Allergic Asthma ◽  
Goblet Cell ◽  
Airway Epithelial Cells ◽  
Lymphoid Cells ◽  
Neuroendocrine Cells ◽  
Airway Epithelial ◽  
Branch Points ◽  
Cell Hyperplasia ◽  
Pulmonary Neuroendocrine Cells ◽  
Group 2

Pulmonary neuroendocrine cells (PNECs) are rare airway epithelial cells whose function is poorly understood. Here we show that Ascl1-mutant mice that have no PNECs exhibit severely blunted mucosal type 2 response in models of allergic asthma. PNECs reside in close proximity to group 2 innate lymphoid cells (ILC2s) near airway branch points. PNECs act through calcitonin gene-related peptide (CGRP) to stimulate ILC2s and elicit downstream immune responses. In addition, PNECs act through the neurotransmitter γ-aminobutyric acid (GABA) to induce goblet cell hyperplasia. The instillation of a mixture of CGRP and GABA in Ascl1-mutant airways restores both immune and goblet cell responses. In accordance, lungs from human asthmatics show increased PNECs. These findings demonstrate that the PNEC-ILC2 neuroimmunological modules function at airway branch points to amplify allergic asthma responses.

Synchronous neurite branchings in single goldfish retinal ganglion cells

1991 ◽  
Vol 6 (5) ◽  
pp. 537-549 ◽  
Author(s):  
A. T. Ishida ◽  
M.- H. Cheng
Keyword(s):  
Retinal Ganglion Cells ◽  
Time Course ◽  
Ganglion Cells ◽  
Single Cells ◽  
Amacrine Cells ◽  
Retinal Ganglion ◽  
Branch Points ◽  
Branch Formation ◽  
The Times

AbstractWe have examined the time course of branch formation in neurites of retinal ganglion cells isolated from adult goldfish (Carassius auratus). These neurites elongate at approximately 13 μm/h, and usually branch by bifurcation of growth cones at their tips. The times elapsed between branchings in different neurites of single cells can be described by a Poisson distribution with a mean interval of approximately 2 h. As predicted by this distribution, a relatively large number of branchings occur simultaneously in different neurites of individual cells. Simultaneous branchings of neurites elongating at a common rate generate branch points that lay equidistant from their soma. Since similar branching patterns can be seen in dendrites of retinal ganglion and amacrine cells in situ, these results are consistent with the possibility that dendrites of individual neurons branch synchronously and grow at common rates during development.

DYNAMICAL BEHAVIOR OF NATURAL CONVECTION IN A DOUBLE-LOOP SYSTEM

1989 ◽  
Vol 2 (1) ◽  
pp. 13-26 ◽  
Author(s):  
P. Ehrhard ◽  
Ch. Marcher ◽  
U. Múller
Keyword(s):  
Natural Convection ◽  
Dynamical Behavior ◽  
Loop System ◽  
Double Loop

2.2. Working Group 2: Conceptual Definitions of Reference Coordinate Systems for Earth Dynamics

1975 ◽  
Vol 26 ◽  
pp. 21-26
Keyword(s):  
Coordinate System ◽  
Working Group ◽  
General Character ◽  
Coordinate Systems ◽  
Reference Coordinate System ◽  
Group 2 ◽  
Definition Of ◽  
Earth Dynamics

An ideal definition of a reference coordinate system should meet the following general requirements:1. It should be as conceptually simple as possible, so its philosophy is well understood by the users.2. It should imply as few physical assumptions as possible. Wherever they are necessary, such assumptions should be of a very general character and, in particular, they should not be dependent upon astronomical and geophysical detailed theories.3. It should suggest a materialization that is dynamically stable and is accessible to observations with the required accuracy.

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