scholarly journals A Temperature-Dependent, Variable-Stiffness Endoscopic Robotic Manipulator with Active Heating and Cooling

2020 ◽  
Vol 48 (6) ◽  
pp. 1837-1849
Author(s):  
Huu Minh Le ◽  
Phuoc Thien Phan ◽  
Cao Lin ◽  
Liu Jiajun ◽  
Soo Jay Phee
Keyword(s):  
Variable Stiffness ◽  
Robotic Manipulator ◽  
Temperature Dependent ◽  
Heating And Cooling

scholarly journals Spring Effects on Workspace and Stiffness of a Symmetrical Cable-Driven Hybrid Joint

Symmetry ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 101 ◽  
Author(s):  
Shan Zhang ◽  
Zheng Sun ◽  
Jili Lu ◽  
Lei Li ◽  
Chunlei Yu ◽  
...  
Keyword(s):  
Variable Stiffness ◽  
Robotic Manipulator ◽  
Spring Model ◽  
Cable Tension ◽  
Stiffness Analysis ◽  
Hybrid Joint ◽  
Compression Spring ◽  
Spring Force ◽  
Basic Parameters ◽  
Stiffness Characteristics

This paper aims to investigate how to determine the basic parameters of the helical compression spring which supports a symmetrical cable-driven hybrid joint (CDHJ) towards the elbow joint of wheelchair-mounted robotic manipulator. The joint design of wheelchair-mounted robotic manipulator needs to consider lightweight but robust, workspace requirements, and variable stiffness elements, so we propose a CDHJ which becomes a variable stiffness joint due the spring under bending and compression provides nonlinear stiffness characteristics. Intuitively, different springs will make the workspace and stiffness of CDHJ different, so we focus on studying the spring effects on workspace and stiffness of CDHJ for its preliminary design. The key to workspace and stiffness analysis of CDHJ is the cable tension, the key to calculate the cable tension is the lateral bending and compression spring model. The spring model is based on Castigliano’s theorem to obtain the relationship between spring force and displacement. The simulation results verify the correctness of the proposed spring model, and show that the spring, with properly chosen parameters, can increase the workspace of CDHJ whose stiffness also can be adjusted to meet the specified design requirements. Then, the modelling method can be extended to other cable-driven mechanism with a flexible compression spring.

scholarly journals Analysis on variable stiffness of a cable-driven parallel–series hybrid joint toward wheelchair-mounted robotic manipulator

2019 ◽  
Vol 11 (4) ◽  
pp. 168781401984628 ◽  
Author(s):  
Shan Zhang ◽  
Dongxing Cao ◽  
Bin Hou ◽  
Shuai Li ◽  
Hong Min ◽  
...  
Keyword(s):  
Variable Stiffness ◽  
Robotic Manipulator ◽  
Hybrid Joint ◽  
Parallel Series

A Transient Elastic-Plastic Thermal Stress Analysis of Flame Forming

1973 ◽  
Vol 95 (1) ◽  
pp. 163-171 ◽  
Author(s):  
Y. Iwamura ◽  
E. F. Rybicki
Keyword(s):  
Thermal Stress ◽  
Stress Analysis ◽  
Material Properties ◽  
Transient Behavior ◽  
Heated Plate ◽  
Plastic Range ◽  
Temperature Dependent ◽  
Elastic Plastic ◽  
Heating And Cooling ◽  
Flame Forming

The work described here is part of a larger experimental and theoretical program directed at obtaining a better understanding of the mechanics of flame bending. A capability for predicting the transient behavior of a line heated plate during heating and cooling is presented. Material properties are temperature dependent. Elastic-plastic stress-strain relations are used. Material unloading from the plastic range is treated. Deformations of a plate are predicted at various times during heating and cooling and compared with experimental results. The analysis is also carried out for consecutive heating and cooling cycles.

scholarly journals Determination of allowable fluid temperature during start-up operation of outlet header under the assumption of constant and temperature-dependent material properties

2013 ◽  
Vol 34 (3) ◽  
pp. 3-14
Author(s):  
Dariusz Rząsa ◽  
Piotr Duda
Keyword(s):  
Power Plants ◽  
Operation Time ◽  
Optimum Operating ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Temperature Dependent ◽  
Allowable Limit ◽  
Heating And Cooling ◽  
Start Up ◽  
Operation Cycle

Abstract Modern supercritical power plants operate at very high temperatures and pressures. Thus the construction elements are subjected to both high thermal and mechanical loads. As a result high stresses in those components are created. In order to operate safely, it is important to monitor stresses, especially during start-up and shut-down processes. The maximum stresses in the construction elements should not exceed the allowable stresses that are defined according to boiler regulations. It is important to find optimum operating parameters, that can assure safe heating and cooling processes. The optimum parameters define temperature and pressure histories that can keep the highest stresses within allowable limit and reduce operation time as much as possible. In this paper a new numerical method for determining optimum working fluid parameters is presented. In this method, properties of steel can be assumed as constant or temperature dependent. The constant value is taken usually at the average temperature of the operation cycle. For both cases optimal parameters are determined. Based on these parameters start-up operations for both cases are conducted. During entire processes stresses in the heated element are monitored. The results obtained are compared with German boiler regulations - Technische Regeln fur Dampfkessel 301.

Study of the Temperature Field in Microchannels of a PDMS Chip With Embedded Local Heater Using Temperature-Dependent Fluorescent Dye

2005 ◽  
Author(s):  
Rachel Fu ◽  
Bo Xu ◽  
Dongqing Li
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Thermal Response ◽  
Microfluidic Devices ◽  
Fluorescent Dye ◽  
Temperature Dependent ◽  
Heating And Cooling ◽  
Liquid Samples ◽  
Temperature Levels ◽  
Pdms Chip

This paper presents a simple microheater design for microfluidic devices by embedding resistance wire into a PDMS chip, and the results of an experimental study of the thermal response of liquid samples in the PDMS chip with the embedded local heater. Temperature-dependent fluorescent dye was used to measure the temperature distribution within a microchannel heated by the local heater. Two heater configurations were built, tested, and compared with numerical simulation. Through comparing the performance of these two configurations, heating and cooling rates and uniformity of the temperature field were evaluated. Additionally, thermal cycling at two different temperature levels was achieved by controlling the power of the local heater.

scholarly journals Effect of polyoxymethylene (POM-H Delrin) off-gassing within the Pandora head sensor on direct-sun and multi-axis formaldehyde column measurements in 2016–2019

2021 ◽  
Vol 14 (1) ◽  
pp. 647-663
Author(s):  
Elena Spinei ◽  
Martin Tiefengraber ◽  
Moritz Müller ◽  
Manuel Gebetsberger ◽  
Alexander Cede ◽  
...  
Keyword(s):  
Spectral Range ◽  
Reference Spectrum ◽  
Temperature Dependent ◽  
Heating And Cooling ◽  
Time Period ◽  
Exponential Temperature Dependence ◽  
Formaldehyde Production ◽  
Sensor Temperature ◽  
Short Time ◽  
Entire Spectral Range

Abstract. Analysis of formaldehyde measurements by the Pandora spectrometer systems between 2016 and 2019 suggested that there was a temperature-dependent process inside the Pandora head sensor that emitted formaldehyde. Some parts in the head sensor were manufactured from the thermal plastic polyoxymethylene homopolymer (E.I. Du Pont de Nemour &amp; Co., USA; POM-H Delrin®) and were responsible for formaldehyde production. Laboratory analysis of the four Pandora head sensors showed that internal formaldehyde production had exponential temperature dependence with a damping coefficient of 0.0911±0.0024 ∘C−1 and the exponential function amplitude ranging from 0.0041 to 0.049 DU. No apparent dependency on the head sensor age and heating and cooling rates was detected. The total amount of formaldehyde internally generated by the POM-H Delrin components and contributing to the direct-sun measurements were estimated based on the head sensor temperature and solar zenith angle of the measurements. Measurements in winter, during colder (< 10 ∘C) days in general, and at high solar zenith angles (> 75∘) were minimally impacted. Measurements during hot days (> 28 ∘C) and small solar zenith angles had up to 1 DU (2.69×1016 molec. cm−2) contribution from POM-H Delrin parts. Multi-axis differential slant column densities were minimally impacted (<0.01 DU) due to the reference spectrum being collected within a short time period with a small difference in head sensor temperature. Three new POM-H Delrin free Pandora head sensors (manufactured in summer 2019) were evaluated for temperature-dependent attenuation across the entire spectral range (300 to 530 nm). No formaldehyde absorption or any other absorption above the instrumental noise was observed across the entire spectral range.

scholarly journals Heat transfer under a pulsed slot turbulent impinging jet at large temperature differences

2010 ◽  
Vol 14 (1) ◽  
pp. 271-281 ◽  
Author(s):  
Peng Xu ◽  
Arun Mujumdar ◽  
Hee Poh ◽  
Boming Yu
Keyword(s):  
Target Surface ◽  
Impinging Jet ◽  
Impinging Jets ◽  
Effect Of Temperature ◽  
Large Temperature ◽  
Geometrical Parameters ◽  
Temperature Dependent ◽  
Nusselt Numbers ◽  
Heating And Cooling ◽  
Nusselt Number Distribution

Pulsed impinging jets have received increasing interest for their potential in heat and mass transfer enhancement. However, published results on effects of pulsations under different flow and geometrical parameters have shown conflicting results. To further understand the flow and thermal processes in pulsed impinging jets, a numerical investigation has been performed on a two dimensional pulsed turbulent impinging jet under large temperature differences between the jet flow and the impinging surface to examine the effect of temperature-dependent thermophysical properties along with pulsation of the jet on the local Nusselt number distribution on the target surface. The numerical results show that the local time-averaged Nusselt numbers calculated with various thermal property values at the jet, film and impingement surface temperatures differ significantly for large temperature difference cases (>100 K). A parametric study for both heating and cooling cases indicates that no obvious enhancement by single sinusoidal pulsation can be found under current conditions except for cases with large temperature differences at distances far from stagnation point, i.e. in the wall jet region.

scholarly journals Numerical Analysis of Polymer Composites for Actuation

2020 ◽  
Vol 30 (5-6) ◽  
pp. 211-216
Author(s):  
Shivashankar Hiremath ◽  
Vidyashree Sangappa ◽  
Sangamesh Rajole ◽  
Satyabodh Kulkarni
Keyword(s):  
Composite Material ◽  
Numerical Analysis ◽  
Polymer Composite ◽  
Composite Beam ◽  
Room Temperature ◽  
Composite Beams ◽  
Temperature Dependent ◽  
Thermal Actuators ◽  
Heating And Cooling ◽  
Composite Properties

The design of a polymer composite actuator is essential for micro and nano applications. Thus, the composite material may deform or deflects as specific stimuli are applied, such as heat, electrical, light source, etc. The deformation of the composite material is caused by the type of stimulus applied. Hence, while it is heated, the expansion takes place quickly, and the heating is shut down, the material shrinks very slowly. In the present investigation, this phenomenon is mainly studied in the actuation of composite beams. Numerical analysis of carbon black filled polymer composite beam expansion, and contraction is being analyzed in this research. The structure of the beam has been created, and the composite properties are incorporated into the beam, and the uniform heat source is applied on to the surface of the beam. The heating and cooling of the composite material predict the increase and decrease in the temperature of the beam. The numerical analysis of the temperature-dependent expansion and contraction of the composite beam has been carried out successfully. An increase in temperature is observed to signify the slight expansion in the composite beam, whereas the contraction of the composite beam takes a longer time to reach room temperature. Also, the increase in the content of the filler leads to a decrease in the expansion of the composite beam. The numerical simulation of the polymer composite thus provides a solid platform for the experimental study of thermal actuators.

scholarly journals Thermal Damping of Weak Magnetosonic Turbulence in the Interstellar Medium

2021 ◽  
Vol 922 (1) ◽  
pp. 10
Author(s):  
Kedron Silsbee ◽  
Alexei V. Ivlev ◽  
Munan Gong
Keyword(s):  
Dispersion Relation ◽  
Interstellar Medium ◽  
Neutral System ◽  
Analytic Approximation ◽  
Cutoff Wavelength ◽  
Temperature Dependent ◽  
Compressive Wave ◽  
Heating And Cooling ◽  
Two Fluid ◽  
Turbulent Cascade

Abstract We present a generic mechanism for the thermal damping of compressive waves in the interstellar medium (ISM), occurring due to radiative cooling. We solve for the dispersion relation of magnetosonic waves in a two-fluid (ion-neutral) system in which density- and temperature-dependent heating and cooling mechanisms are present. We use this dispersion relation, in addition to an analytic approximation for the nonlinear turbulent cascade, to model dissipation of weak magnetosonic turbulence. We show that in some ISM conditions, the cutoff wavelength for magnetosonic turbulence becomes tens to hundreds of times larger when the thermal damping is added to the regular ion-neutral damping. We also run numerical simulations, which confirm that this effect has a dramatic impact on cascade of compressive wave modes.

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