scholarly journals Measurements of Magnetic Fiber Dynamics in Magnetic Fields using Optical and Electrical Techniques

2021 ◽  
Author(s):  
◽  
Shaun Swan
Keyword(s):  
Mathematical Modeling ◽  
Optical Observations ◽  
Optical Methods ◽  
Fiber Suspension ◽  
Fluid Viscosity ◽  
Fiber Concentration ◽  
Transmission Microscopy ◽  
Ceramic Slurry ◽  
Fiber Dynamics ◽  
Magnetically Assisted

<p>The fabrication of piezoelectric ceramics (Piezoceramics) currently relies on a costly dice and fill process to create an array of aligned pillars. These pillars act as waveguides, improving the performance of the piezoceramic wafers over the bulk piezoceramic alone. It is theorised the creation of aligned pores in the piezoceramic may exhibit the same waveguiding effect, removing the need for the dice and fill process.  A technique for creating these pores is in development at Callaghan Innovation, New Zealand, where nickel coated carbon fibers are added to the ceramic slurry, aligned with a magnetic field, and attracted to the bottom of a mold. The number of fibers and degree of alignment dictate the waveguiding effectiveness and hence the performance of the piezoceramic. Additionally the time taken for fibers to form an array in the bottom of the mold dictate the piezoceramics fabrication time. Thus it is crucial to be able to measure the alignment and magnetically assisted sedimentation of these fibers in-situ. However the ceramic slurry is opaque, hence the optical methods traditionally can not be implemented.  This thesis describes the development and implementation of an electrical technique using the anisotropic conductance of fibers, for measuring fiber dynamics during the fabrication of piezoceramics. The results of this electrical technique are compared to both optical monitoring results in a transparent solution, and models for the motion of rigid cylinders in a fluid suspension.  The change in conductance corresponding to fiber rotation was found to have a time constant corresponding to fiber rotation which is a scalar multiple of that of transmission microscopy and the mathematical modeling. This is a product of the geometry of the electrode configurations used to measure conductance. Furthermore, for fiber rotation, the fiber concentration in the solution changes the effective fluid viscosity due to hydrodynamic turbulence created by the rotating fibers.  The conductance change corresponding to the magnetically assisted fiber settling is in good accordance with both the optical observations and mathematical modeling for 50 mPas solutions, however for 30 mPas solutions the modeling underestimates the settling time by 20%. The maximum fiber concentration to create a single layer of aligned fibers in the bottom of the mold was found to be 12 fibers=mm³. Exceeding this limit results in a secondary and tertiary layer of fibers forming directly below the fiber suspension injection location.</p>

scholarly journals Measurements of Magnetic Fiber Dynamics in Magnetic Fields using Optical and Electrical Techniques

2021 ◽  
Author(s):  
◽  
Shaun Swan
Keyword(s):  
Mathematical Modeling ◽  
Optical Observations ◽  
Optical Methods ◽  
Fiber Suspension ◽  
Fluid Viscosity ◽  
Fiber Concentration ◽  
Transmission Microscopy ◽  
Ceramic Slurry ◽  
Fiber Dynamics ◽  
Magnetically Assisted

<p>The fabrication of piezoelectric ceramics (Piezoceramics) currently relies on a costly dice and fill process to create an array of aligned pillars. These pillars act as waveguides, improving the performance of the piezoceramic wafers over the bulk piezoceramic alone. It is theorised the creation of aligned pores in the piezoceramic may exhibit the same waveguiding effect, removing the need for the dice and fill process.  A technique for creating these pores is in development at Callaghan Innovation, New Zealand, where nickel coated carbon fibers are added to the ceramic slurry, aligned with a magnetic field, and attracted to the bottom of a mold. The number of fibers and degree of alignment dictate the waveguiding effectiveness and hence the performance of the piezoceramic. Additionally the time taken for fibers to form an array in the bottom of the mold dictate the piezoceramics fabrication time. Thus it is crucial to be able to measure the alignment and magnetically assisted sedimentation of these fibers in-situ. However the ceramic slurry is opaque, hence the optical methods traditionally can not be implemented.  This thesis describes the development and implementation of an electrical technique using the anisotropic conductance of fibers, for measuring fiber dynamics during the fabrication of piezoceramics. The results of this electrical technique are compared to both optical monitoring results in a transparent solution, and models for the motion of rigid cylinders in a fluid suspension.  The change in conductance corresponding to fiber rotation was found to have a time constant corresponding to fiber rotation which is a scalar multiple of that of transmission microscopy and the mathematical modeling. This is a product of the geometry of the electrode configurations used to measure conductance. Furthermore, for fiber rotation, the fiber concentration in the solution changes the effective fluid viscosity due to hydrodynamic turbulence created by the rotating fibers.  The conductance change corresponding to the magnetically assisted fiber settling is in good accordance with both the optical observations and mathematical modeling for 50 mPas solutions, however for 30 mPas solutions the modeling underestimates the settling time by 20%. The maximum fiber concentration to create a single layer of aligned fibers in the bottom of the mold was found to be 12 fibers=mm³. Exceeding this limit results in a secondary and tertiary layer of fibers forming directly below the fiber suspension injection location.</p>

scholarly journals Acoustic and optical methods to infer water transparency at Time Series Station Spiekeroog, Wadden Sea

Ocean Science ◽  
2016 ◽  
Vol 12 (6) ◽  
pp. 1155-1163 ◽  
Author(s):  
Anne-Christin Schulz ◽  
Thomas H. Badewien ◽  
Shungudzemwoyo P. Garaba ◽  
Oliver Zielinski
Keyword(s):  
Time Series ◽  
Wadden Sea ◽  
Acoustic Doppler Current Profiler ◽  
Water Transparency ◽  
Optical Observations ◽  
Optical Methods ◽  
Acoustic Measurements ◽  
Data Set ◽  
Backscatter Signal ◽  
Current Profiler

Abstract. Water transparency is a primary indicator of optical water quality that is driven by suspended particulate and dissolved material. A data set from the operational Time Series Station Spiekeroog located at a tidal inlet of the Wadden Sea was used to perform (i) an inter-comparison of observations related to water transparency, (ii) correlation tests among these measured parameters, and (iii) to explore the utility of both acoustic and optical tools in monitoring water transparency. An Acoustic Doppler Current Profiler was used to derive the backscatter signal in the water column. Optical observations were collected using above-water hyperspectral radiometers and a submerged turbidity metre. Bio-fouling on the turbidity sensors optical windows resulted in measurement drift and abnormal values during quality control steps. We observed significant correlations between turbidity collected by the submerged metre and that derived from above-water radiometer observations. Turbidity from these sensors was also associated with the backscatter signal derived from the acoustic measurements. These findings suggest that both optical and acoustic measurements can be reasonable proxies of water transparency with the potential to mitigate gaps and increase data quality in long-time observation of marine environments.

NUMERICAL RESEARCH ON THE EFFECT OF FIBERS ON THE PROPERTY OF TURBULENT FIBER SUSPENSION IN A CHANNEL

2009 ◽  
Vol 23 (03) ◽  
pp. 509-512 ◽  
Author(s):  
SUHUA SHEN ◽  
JIANZHONG LIN
Keyword(s):  
Reynolds Number ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Channel Flow ◽  
Turbulent Channel Flow ◽  
Fiber Suspension ◽  
Additional Stress ◽  
Mean Velocity ◽  
Navier Stokes Equation ◽  
Fiber Concentration

To explore the rheological property in turbulent channel flow of fiber suspensions, the equation of probability distribution function for mean fiber orientation and the Reynolds averaged Navier-Stokes equation with the term of additional stress resulted from fibers were solved with numerical methods to get the distributions of the mean velocity and turbulent kinetic energy. The simulation results show that the effect of fibers on turbulent channel flow is equivalent to an additional viscosity. The turbulent velocity profiles of fiber suspension become gradually sharper by increasing the fiber concentration and/or decreasing the Reynolds number. The turbulent kinetic energy will increase with increasing Reynolds number and fiber concentration.

scholarly journals Direct observations of diel biological CO<sub>2</sub> fixation in the oceans

2012 ◽  
Vol 9 (2) ◽  
pp. 2153-2168
Author(s):  
H. Thomas ◽  
S. E. Craig ◽  
B. J. W. Greenan ◽  
W. Burt ◽  
G. J. Herndl ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Mixed Layer Depth ◽  
Early Morning ◽  
Heat Fluxes ◽  
Optical Observations ◽  
Optical Methods ◽  
Diel Periodicity ◽  
Net Community Production ◽  
Diel Cycles ◽  
Wide Range

Abstract. Much of the variability in the surface ocean's carbon cycle can be attributed to the availability of sunlight, through processes such as heat fluxes and photosynthesis, which regulate over a wide range of time scales. The critical processes occurring on timescales of a day or less, however, have undergone few investigations, and most of these have been limited to a time span of several days to months, or exceptionally, for longer periods. Optical methods have helped to infer short-term biological variability, however corresponding investigations of the oceanic CO2 system are lacking. We employ high-frequency CO2and optical observations covering the full seasonal cycle on the Scotian Shelf, Northwestern Atlantic Ocean, in order to unravel diel periodicity of the surface ocean carbon cycle and its effects on annual budgets. Significant diel periodicity occurs only if the water column is sufficiently stable as observed during seasonal warming. During that time biological CO2 drawdown, or net community production (NCP), is delayed for several hours relative to the onset of photosynthetically available radiation (PAR), due to diel cycles in chlorophyll-a concentration and to grazing, both of which, we suggest, inhibit NCP in the early morning hours. In summer, NCP decreases by more than 90 %, coinciding with the seasonal minimum of the mixed layer depth and resulting in the disappearance of the diel CO2 periodicity in the surface waters.

scholarly journals Acoustic and optical methods to infer water transparency at the Time Series Station Spiekeroog, Wadden Sea (southern North Sea)

2016 ◽  
Author(s):  
Anne-Christin Schulz ◽  
Thomas H. Badewien ◽  
Shungudzemwoyo P. Garaba ◽  
Oliver Zielinski
Keyword(s):  
Time Series ◽  
Water Column ◽  
Wadden Sea ◽  
Acoustic Doppler Current Profiler ◽  
Water Transparency ◽  
Optical Observations ◽  
Optical Methods ◽  
Acoustic Measurements ◽  
Data Set ◽  
Acoustic Backscattering

Abstract. Water transparency is a key indicator of optical water quality that is driven by suspended particulate and dissolved material. In this study we carried out an intercomparison of observations related to water transparency, determine correlations among the measured parameters and demonstrate the utility of both acoustic and optical tools in monitoring water transparency. The data set used here is from the operational Time Series Station Spiekeroog located at a tidal inlet of the Wadden Sea. An Acoustic Doppler Current Profiler was used to obtain acoustic measurements in the water column. Optical observations were determined using a set of three radiometers above water to collect radiometric quantities and a turbidity sensor within the water column. Bio-fouling was identified as a source of anomaly in turbidity measurements. We observed significant correlations between in-situ optically measured turbidity and derived turbidity from above water color sensing and acoustic backscattering strength. These findings underline that both optical and acoustic measurements can be reasonable proxies of water transparency with the potential to mitigate gaps and increase data quality in long-time observation of marine environments.

scholarly journals Rheological Behavior of Tomato Fiber Suspensions Produced by High Shear and High Pressure Homogenization and Their Application in Tomato Products

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Yong Wang ◽  
Ping Sun ◽  
He Li ◽  
Benu P. Adhikari ◽  
Dong Li
Keyword(s):  
High Pressure ◽  
Rheological Properties ◽  
Loss Modulus ◽  
Fiber Suspension ◽  
High Pressure Homogenization ◽  
Fiber Suspensions ◽  
High Shear ◽  
Fiber Concentration ◽  
Tomato Ketchup ◽  
And Storage

This study investigated the effects of high shear and high pressure homogenization on the rheological properties (steady shear viscosity, storage and loss modulus, and deformation) and homogeneity in tomato fiber suspensions. The tomato fiber suspensions at different concentrations (0.1%–1%, w/w) were subjected to high shear and high pressure homogenization and the morphology (distribution of fiber particles), rheological properties, and color parameters of the homogenized suspensions were measured. The homogenized suspensions were significantly more uniform compared to unhomogenized suspension. The homogenized suspensions were found to better resist the deformation caused by external stress (creep behavior). The apparent viscosity and storage and loss modulus of homogenized tomato fiber suspension are comparable with those of commercial tomato ketchup even at the fiber concentration as low as 0.5% (w/w), implying the possibility of using tomato fiber as thickener. The model tomato sauce produced using tomato fiber showed desirable consistency and color. These results indicate that the application of tomato fiber in tomato-based food products would be desirable and beneficial.

scholarly journals Fiber Suspensions in Turbulent flow with Two-Point Correlation

1970 ◽  
Vol 46 (2) ◽  
pp. 265-270 ◽  
Author(s):  
SE Ahmed ◽  
MS Alam Sarker
Keyword(s):  
Mathematical Modeling ◽  
Flow Field ◽  
Turbulent Flow ◽  
Pressure Fluctuations ◽  
Equation Of Motion ◽  
Second Order ◽  
Fiber Suspension ◽  
Fiber Suspensions ◽  
Velocity Fluctuations ◽  
Point Correlation

The equation of motion for turbulent flow of fiber suspensions has been derived in terms of correlation tensors of second order. Mathematical modeling of fiber suspensions in the turbulent flow is discussed including the correlation between the pressure fluctuations and velocity fluctuations at two points of the flow field, where the correlation tensors are the functions of space coordinates, distance between two points and the time. Keywords: Fiber suspension; Turbulent flow; Correlation.DOI: http://dx.doi.org/10.3329/bjsir.v46i2.8206 Bangladesh J. Sci. Ind. Res. 46(2), 265-270, 2011

scholarly journals IV. Physico-chemical determinations at high pressures by optical methods

1913 ◽  
Vol 212 (484-496) ◽  
pp. 117-148 ◽  
Keyword(s):  
High Pressures ◽  
Optical Observations ◽  
Optical Methods ◽  
Small Glass ◽  
Physico Chemical ◽  
Glass Tubes ◽  
Pressure Bomb ◽  
The Subject ◽  
Transition Points

In the course of his well-known investigations concerning the compressibility of gases and liquids, Amagat made some series of measurements taking observations through two small glass windows fitted to his high-pressure bomb (“méthode des regards”),* and he also twice made an attempt to use a similar arrangement for the determination of melting and crystallization at high pressures. His first paper on these subjects deals with the melting and with the formation of two different kinds of crystals of carbon tetrachloride. The highest pressure employed was 1,160 atmospheres. The second paper, in which a somewhat different arrangement of the glass windows was used, deals with the crystallization of ice at temperatures below zero under the influence of high pressures.^ In a summarizing paper Amagat§states that he occasionally was able to reach pressures of about 1,600 atmospheres before the glass windows were broken, but observations were not actually made at higher pressures than 1,000 atmospheres. In this paper a sketch of the apparatus is also given. Amagat states that he met with severe difficulties during these investigations, and he has not pursued the subject further. Later melting-points and transition-points of some “liquo-crystalline” substances have been measured in Jena glass tubes up to 300 atmospheres by Hullett, and other optical observations at pressures above that of the atmosphere have been made by Rothmund (maximum 500 atmospheres), Röntgen and Zehnder, Sierstema, Liveing and Dewar, Hutton and Petavel,§§ and Duffield, but in these investigations the pressures have, as a rule, not exceeded 100 atmospheres.

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