Discussion on the neutral angle of macrocrack-microcrack interaction

1996 ◽  
Vol 54 (4) ◽  
pp. 597-599 ◽  
Author(s):  
X.-M. Wang ◽  
S. Gao ◽  
Y.-P. Shen
Keyword(s):  
Microcrack Interaction ◽  
Neutral Angle

Multi-Objective Optimization of Human Gait With a Discomfort Function

2016 ◽  
Author(s):  
Hyun-Jung Kwon ◽  
Hyun-Joon Chung ◽  
Yujiang Xiang
Keyword(s):  
Joint Torque ◽  
Upper Body ◽  
Whole Body ◽  
Human Gait ◽  
Multi Objective Optimization ◽  
Joint Angles ◽  
Backward Walking ◽  
Multi Objective ◽  
Body Model ◽  
Neutral Angle

The objective of this study was to develop a discomfort function for including a high DOF upper body model during walking. A multi-objective optimization (MOO) method was formulated by minimizing dynamic effort and the discomfort function simultaneously. The discomfort function is defined as the sum of the squares of deviation of joint angles from their neutral angle positions. The dynamic effort is the sum of the joint torque squared. To investigate the efficacy of the proposed MOO method, backward walking simulation was conducted. By minimizing both dynamic effort and the discomfort function, a 3D whole body model with a high DOF upper body for walking was demonstrated successfully.

Index finger position and force of the human first dorsal interosseus and its ulnar nerve antagonist

1994 ◽  
Vol 77 (2) ◽  
pp. 987-997 ◽  
Author(s):  
I. Zijdewind ◽  
D. Kernell
Keyword(s):  
Ulnar Nerve ◽  
Index Finger ◽  
Maximum Voluntary Contraction ◽  
Normal Subjects ◽  
Voluntary Contraction ◽  
Abduction Angle ◽  
Hand Position ◽  
First Dorsal Interosseus ◽  
Length Analysis ◽  
Neutral Angle

In normal subjects, maximum voluntary contraction (MVC) and electrical ulnar nerve stimulation (UNS; 30-Hz bursts of 0.33 s) were systematically compared with regard to the forces generated in different directions (abduction/adduction and flexion) and at different degrees of index finger abduction. With a “resting” hand position in which there was no index finger abduction, UNS produced about one-half of the abduction force elicited by an MVC (mean ratio 51%). Qualitatively, such a discrepancy would be expected, because UNS activates two index finger muscles with opposing actions in the abduction/adduction plane of torques: the first dorsal interosseus (FDI) and the first palmar interosseus (FPI). The abduction forces produced by MVC and UNS were very sensitive to index finger abduction angle: at a maximum degree of abduction, the UNS-generated force even reversed its direction of action to adduction (with FPI dominating) and the abduction MVC declined to 37% of that in the resting hand position. Inasmuch as these declines in MVC- and UNS-generated abduction force could not be explained by a change in moment arm, the main alternative seemed to be abduction-associated alterations in FDI fiber length (analysis by previously published biomechanical data). The FDI and FPI were further compared by application of a UNS-generated fatigue test (5-min burst stimulation), with the index finger kept at a "neutral" angle, i.e., the abduction angle at which, in the unfatigued state, the forces of the FDI and FPI were in balance (zero net UNS-generated abduction/adduction force).(ABSTRACT TRUNCATED AT 250 WORDS)

On the strong crack-microcrack interaction problem

1992 ◽  
Vol 56 (1) ◽  
pp. R9-R14 ◽  
Author(s):  
M. Gorelik ◽  
A. Chudnovsky
Keyword(s):  
Microcrack Interaction ◽  
Interaction Problem

scholarly journals Carpal Tunnel Syndrome Soft Relief Device for Typing Applications

2017 ◽  
Author(s):  
Mengjia Zhu ◽  
Wade Adams ◽  
Panagiotis Polygerinos
Keyword(s):  
Carpal Tunnel Syndrome ◽  
Median Nerve ◽  
Real Time ◽  
Carpal Tunnel ◽  
Severe Pain ◽  
General Trend ◽  
Working Population ◽  
Tunnel Syndrome ◽  
Neutral Angle

Carpal Tunnel Syndrome (CTS) affects roughly 3%–6% of the working population ages 18–64 [1]. This affliction is caused by applying stress on the median nerve that is routed through the carpal tunnel while it is at a positive or negative angle, greater than 15 degrees in either direction, to the human wrist [2]. The median nerve can become inflamed and swollen due to pressure from the palmar carpal ligament causing numbness, stiffness and in some cases severe pain. Tasks like typing can become nearly impossible when the median nerve is inflamed. A number of products on the market and research prototypes have been suggested that try to alleviate CTS strains, however, these designs are generally passive e.g. braces, splints, etc. Instead of actively trying to adjust the wrist angle, the general trend is to prop the wrist up with some sort of rigid ramp, similar to the bottom of a keyboard [3]. The goal of this work is to design a wearable, soft-actuated, robotic sleeve that will dynamically adjust the position of the wrist in real-time to a neutral angle to prevent or release CTS strains.

A Survey of Macro-Microcrack Interaction Problems

2000 ◽  
Vol 53 (5) ◽  
pp. 117-146 ◽  
Author(s):  
Vera Petrova ◽  
Vitauts Tamuzs ◽  
Natalia Romalis
Keyword(s):  
Three Dimensional ◽  
Elastic Solid ◽  
Singular Integral Equations ◽  
Crack Location ◽  
Penny Shaped Crack ◽  
Shaped Crack ◽  
Microcrack Interaction ◽  
The Impact ◽  
The Continuum ◽  
Model Approach

The results obtained on the problem of the interaction between a large crack and an array of microcracks or other microdefects are reviewed. The following problems are considered: interaction of main crack with microcracks in the two-dimensional case at tensile, shear or combined stress state; a closure of macro or microcracks as a result of their interaction, and the influence of this phenomenon on the stress intensity factor; the thermal cracking of an elastic solid caused by the macro-microcracks interaction and cracks closure; the interaction of a crack with an array of small pores or rigid inclusions; three-dimensional problems of the interaction of a penny-shaped crack with small penny-shaped microcracks. Discussed analytical results are based on the asymptotic analysis and the series solution to systems of singular integral equations describing the interaction of the macrocrack and microdefects. The series solutions were obtained with respect to the small parameter representing the ratio of micro- to macrocrack sizes. Throughout the review, the known solutions on the crack interaction are surveyed. The comparison with solutions to other relevant problems such as an interaction of semi-infinite crack with an array of finite cracks is given. The impact of a close crack location, and a comparison with relevant results of the continuum model approach are discussed. This review article includes 332 references.

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