Self-Exciting Wire Transducer for Time-Varying Strain Measurements

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Grzegorz Cieplok
Keyword(s):  
Time Varying ◽  
Natural Vibrations ◽  
Motion Velocity ◽  
Strain Measurements ◽  
Limiting Cycle ◽  
Impulse System ◽  
Rapid Changes ◽  
The Wire ◽  
Chaotic Nature ◽  
Wire Motion

The solution of a system exciting wire vibrations of a wire sensor allowing one to perform time-varying measurements, including rapid changes and of a chaotic nature, are presented in this paper. The system is based on the typical two-coil solution, in which one of the coils is responsible for exciting the wire vibrations while the other coil is used for recording those vibrations. The task of maintaining and not fading away the natural vibrations of the wire was solved by the excitation of self-exciting vibrations by the impulse system synchronized using the wire motion velocity. The mathematical analysis of the wire motion in the system with the impulse generator, in which the existence of the limiting cycle of the wire natural frequency was proved, is shown in this paper. The computer simulation results, illustrating the metrological possibilities of the solution as well as an example of a physical implementation, are also presented.

Numerical Investigation on the Effects of Sample Wire Motion in a Tube Furnace

2013 ◽  
Vol 300-301 ◽  
pp. 771-774
Author(s):  
Taqi Ahmad Cheema ◽  
Haider Ali ◽  
Kyung Won Kim ◽  
Choon Young Lee ◽  
Moon Kyu Kwak ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Electric Heating ◽  
Tube Furnace ◽  
Heating Zone ◽  
Gas Temperature ◽  
The Wire ◽  
Wire Motion ◽  
Matrix Heat

A tube furnace is a heat treatment device in which a specimen is heated in the presence of an inert gas using electric heating coils embedded in a thermally insulating matrix. Heat flux and temperature gradients of sample during heat treatment in a tube furnace depend on the gas and wire velocities. These parameters were used in this paper for a 2-D axisymmetric numerical study to determine an optimized relationship between the temperature and the sample wire motion. The results show that wire velocity considerably affected the wire temperature distribution and increased the gas temperature to some extent. The phenomenon resulted in the shifting of the heating zone on the wire surface and occurrence of an inner convection heat transfer.

scholarly journals Heavy Metals: Might as Well Jump

2019 ◽  
Vol 7 (2) ◽  
pp. 33
Author(s):  
Neil A. Wilmot
Keyword(s):  
Heavy Metal ◽  
Commodity Prices ◽  
Time Varying ◽  
Fat Tails ◽  
Times Series ◽  
Complex Processes ◽  
Price Series ◽  
New Information ◽  
Complex Process ◽  
Rapid Changes

Financial times series, and commodity prices in particular, are known to exhibit fat tails in the distribution of prices. As with many natural resources price series, the arrival of new information can lead to unexpectedly rapid changes—or jump—in prices. This suggests that natural resource commodity prices should follow a more complex process than geometric Brownian motion (GBM), which is linked to the Gaussian distribution. The presence of jumps (discontinuities) in several heavy metal price series is investigated, as well as time-varying volatility. The results demonstrate that allowing for jumps and time-varying volatility provides statistically important improvements in the modelling or prices, relative to GBM. These complex processes contributed to the fatness of the tails in the distribution of heavy metal price returns.

Theoretical Research on Contact Length in the Rocking Motion Wire Saw

2016 ◽  
Vol 1136 ◽  
pp. 343-349 ◽  
Author(s):  
Hui Huang ◽  
Sheng Long Zheng ◽  
Xi Peng Xu
Keyword(s):  
Line Segment ◽  
Feed Rate ◽  
Contact Length ◽  
Theoretical Research ◽  
Theoretical Equation ◽  
Motion Path ◽  
Wire Saw ◽  
Rocking Motion ◽  
The Wire ◽  
Wire Motion

Rocking motion wire saw with the additional rocking motion of either the wire or the workpiece is a new machining method compared with the traditional wire saw. The length of contact between the wire and the workpiece changes in this new saw process. In this paper, the wire motion and the contact length were theoretically researched. Wire motion path equation with the rocking motion was established. The theoretical equation of the contact length in half a swing period was derived out. The results indicated that the wire motion was a single pendulum movement with a length line segment, which the swing pivot was moved with a feed rate. The contact length had significant changes in half a swing period in the rocking motion wire saw. The contact length varied periodically with the same amplitude in the square ingot sawing, which varied periodically with the variation amplitude in the circle ingot sawing. The contact length with the rocking motion was obviously shorter than the case without the rocking motion for either the square ingot or the circle ingot.

Study on Interference between Wires and Mobile Platform in a Wire-Driven Parallel Manipulator Based on ADAMS

2013 ◽  
Vol 694-697 ◽  
pp. 1671-1674
Author(s):  
Sui Lu Yue ◽  
Qi Lin ◽  
Yi Xin Chen ◽  
Zhao Wang
Keyword(s):  
Simulation Model ◽  
Parallel Manipulator ◽  
Virtual Prototyping ◽  
Mobile Platform ◽  
Time Varying ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Virtual Prototyping Technology ◽  
The Wire ◽  
Hinge Points

In this paper, to avoid interference between wires and a mobile platform in a wire-driven parallel suspension system, the simulation model of time-varying wires structure is established by applying the ADAMS virtual prototyping technology. The law of motion of hinge points is planned when the mobile platform performs a single degree of freedom pitch rotation. Using the simulation model of the time-varying wires structure, the interference is investigated. The results show that the simulation model is able to analyze the interference between wires and the mobile platform rapidly and provides an effective method for the design of the wire-driven parallel mechanism. Therefore, the interference can be avoided in the wire-driven parallel manipulator with time-varying wires structure, and the workspace of the mobile platform can be enlarged.

Study on Time-Varying Wires Structure in Wire-Driven Parallel Manipulators

2011 ◽  
Vol 148-149 ◽  
pp. 987-991 ◽  
Author(s):  
Sui Lu Yue ◽  
Qi Lin ◽  
Ru Bing Liu ◽  
Zhao Wang ◽  
Yi Xin Chen
Keyword(s):  
Parallel Manipulators ◽  
Calculation Model ◽  
Mobile Platform ◽  
Time Varying ◽  
Single Degree Of Freedom ◽  
Motion Equations ◽  
Single Degree ◽  
System A ◽  
Simulation Results ◽  
The Wire

In the paper, the concept of time-varying wires structure is proposed to avoid interference between wires and a mobile platform in a wire-driven parallel suspension system. A mathematical model, a kinematic notation model and a calculation model for interference between wires and the mobile platform have been built for it. When the mobile platform moves at a single degree of freedom pitch rotation, the motion equations of relevant hinge are deduced. The simulation results demonstrate that interference can be avoided in the wire-driven parallel manipulators with time-varying wires structure, and the workspace of the mobile platform may be enlarged. But different motions chosen for the hinge correspond to distinguishable sizes of workspace of the wire-driven parallel manipulators with time-varying wires structure. Therefore, according to the requirements to avoid interference, the motion of the hinge can be designed.

scholarly journals Volatility in Rainfall and Predictability of Droughts in Northwest Bangladesh

2020 ◽  
Vol 12 (23) ◽  
pp. 9810
Author(s):  
Mohammad Ahsan Uddin ◽  
ASM Maksud Kamal ◽  
Shamsuddin Shahid ◽  
Eun-Sung Chung
Keyword(s):  
Drought Index ◽  
Monsoon Rainfall ◽  
Daily Rainfall ◽  
Rainfall Anomaly ◽  
Trend Test ◽  
Time Varying ◽  
Jump Model ◽  
Rapid Changes ◽  
Anomaly Analysis ◽  
Autoregressive Conditional Heteroscedasticity

This study was conducted to evaluate the variability, trends, volatility, and transition patterns of rainfall in drought-prone northwest Bangladesh. Daily rainfall recorded at five stations for the period 1959–2018 were used for this purpose. Non-parametric tests of variability changes, a modified Mann–Kendall trend test, innovative trend analysis (ITA), a generalized autoregressive conditional heteroscedasticity (GARCH)–jump model, and a Markov chain (MC) were used to assess the variability changes, trends, volatility, and transitions in rainfall to understand the possibility of the persistence of droughts and their predictability. The results showed an overall decrease of variability in annual and seasonal rainfall, but an increase in mean pre-monsoon rainfall and a decrease in mean monsoon rainfall. This caused a decrease in pre-monsoon droughts, but few changes in monsoon droughts. The ITA and rainfall anomaly analysis revealed high temporal variability and, thus, rapid shifts in rainfall regimes, which were also supported by the volatility dynamics and time-varying jumps from the GARCH–jump model and the rapid changes in drought index from the MC analysis. Therefore, the lack of drought in recent years cannot be considered as an indicator of declining droughts in the region.

Microstructural Development in Nb-Ti Multifilamentary Superconductors During Processing

1985 ◽  
Vol 43 ◽  
pp. 190-191
Author(s):  
A. W. West
Keyword(s):  
Heat Treatment ◽  
Critical Current Density ◽  
Copper Matrix ◽  
Wire Drawing ◽  
Heat Treatments ◽  
Microstructural Development ◽  
Final Size ◽  
Density Values ◽  
The Wire ◽  
Multifilamentary Superconductors

The influence of the filament microstructure on the critical current density values, Jc, of Nb-Ti multifilamentary superconducting composites has been well documented. However the development of these microstructures during composite processing is still under investigation.During manufacture, the multifilamentary composite is given several heat treatments interspersed in the wire-drawing schedule. Typically, these heat treatments are for 5 to 80 hours at temperatures between 523 and 573K. A short heat treatment of approximately 3 hours at 573K is usually given to the wire at final size. Originally this heat treatment was given to soften the copper matrix, but recent work has shown that it can markedly change both the Jc value and microstructure of the composite.

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