scholarly journals THE DIFFERENCE BETWEEN THE EFFECT OF ELECTROMAGNETIC AND MAGNETIC FIELDS ON THE VISCOSITY COEFFICIENTS OF CUTTING FLUIDS USED IN CUTTING PROCESSES

2021 ◽  
Vol 1 (10) ◽  
Keyword(s):  
Magnetic Fields ◽  
Cutting Fluids ◽  
Viscosity Coefficients ◽  
The Difference ◽  
Cutting Processes

Effect of Magnetic Fields on the Resistance and Microstructure of Al-Cu Alloy during Solidification Processing

2011 ◽  
Vol 287-290 ◽  
pp. 2916-2920
Author(s):  
Chun Yan Ban ◽  
Peng Qian ◽  
Xu Zhang ◽  
Qi Xian Ba ◽  
Jian Zhong Cui
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Turning Points ◽  
Probe Method ◽  
Solidification Processing ◽  
Ac Magnetic Field ◽  
Dc Magnetic Field ◽  
Cu Alloy ◽  
The Difference ◽  
Good Agreement

The resistance of Al-21%Cu alloy under no magnetic field, DC magnetic field and AC magnetic field from liquid to solid was measured by a four-probe method. The difference of resistance versus temperature curves (R-T curves) was analyzed. It is found that the R-T curves of Al-21%Cu alloy are monotone decreasing and have two obvious turning points. Under DC magnetic field, the liquidus and solidus temperatures of the alloy both decrease, while under AC magnetic field, the liquidus and solidus temperatures both increase. There is a good agreement between the microstructure of quenching sample and R-T curves. The mechanism of the effect of magnetic fields was discussed.

scholarly journals Investigation of the Cutting Uid'S Ow and its Thermomechanical Effect on the Cutting Zone Based on Uid-Structure Interaction (FSI) Simulation

2021 ◽  
Author(s):  
Hui Liu ◽  
Markus Meurer ◽  
Daniel Schraknepper ◽  
Thomas Bergs
Keyword(s):  
Metal Cutting ◽  
Negative Impact ◽  
Orthogonal Cutting ◽  
Fluid Simulation ◽  
Cutting Fluid ◽  
Cutting Fluids ◽  
Thermomechanical Effect ◽  
Dimensional Simulation ◽  
On Chip ◽  
Cutting Processes

Abstract Cutting fluids are an important part of today's metal cutting processes, especially when machining aerospace alloys. They offer the possibility to extend tool life and improve cutting performance. However, the equipment and handling of cutting fluids also raises manufacturing costs. To reduce the negative impact of the high cost of cutting fluids, cooling systems and strategies are constantly being optimized. In most existing works, the influences of different cooling strategies on the relevant process parameters, such as tool wear, cutting forces, chip breakage, etc., are empirically investigated. Due to the limitations of experimental methods, analysis and modeling of the working mechanism has so far only been carried out at a relatively abstract level. For a better understanding of the mechanism of cutting fluids, a thermal coupled two-dimensional simulation approach for the orthogonal cutting process was developed in this work. This approach is based on the Coupled Eulerian Lagrangian (CEL) method and provides a detailed investigation of the cutting fluid’s impact on chip formation and tool temperature. For model validation, cutting tests were conducted on a broaching machine. The simulation resolved the fluid behavior in the cutting area and showed the distribution of convective cooling on the tool surface. This work demonstrates the potential of CEL based cutting fluid simulation, but also pointed out the shortcomings of this method.

A MEMS Magnetometer Utilizing a NdFeB Magnet

2015 ◽  
Vol 2015 (DPC) ◽  
pp. 001671-001700
Author(s):  
John J. Tatarchuk ◽  
Colin B. Stevens ◽  
Robert N. Dean
Keyword(s):  
Magnetic Fields ◽  
Printed Circuit Board ◽  
Relaxation Oscillator ◽  
Circuit Board ◽  
Ndfeb Magnet ◽  
Assembly Method ◽  
Variable Capacitance ◽  
The Difference ◽  
Silicon Frame ◽  
Gap Width

A silicon MEMS magnetometer has been developed that utilizes a miniature NdFeB rare earth magnet attached to a silicon platform that is suspended by a dual torsional suspension system. An externally applied out-of-plane magnetic field will cause a magnetic torque to be produced between the external field and the NdFeB magnet, causing a deflection of the suspended silicon platform which can be sensed capacitively. The device measures 5.6 mm X 5.6 mm, with the silicon components being manufactured using bulk micromachining processes. The variable capacitive structure is realized by metalizing the bottom side of the suspended silicon platform to allow the silicon platform to serve as the top electrode. The bottom electrode is provided by a bare pad on a printed circuit board (PCB) to which the frame of the silicon device is attached. This results in a variable capacitance with a nominal value of approximately 3–6 pF, depending on the exact width of the gap. The variable capacitance is large enough to be converted into a variable frequency square wave using a CMOS relaxation oscillator circuit. To realize a practical device, multiple silicon components were manufactured. First, a silicon component had to be manufactured that included the anchor/frame, torsional springs, and suspended platform. To provide protection against destructive over-ranging of the mechanical components during very high accelerations or external magnetic fields, another silicon component was manufactured that provided mechanical stops at the limits of the useful displacement range. Two other components were also manufactured on the same wafer to provide for a cap over the device. Epoxy was used to bond the NdFeB magnet and the various silicon components together. The fabricated devices behaved similarly to their predicted theoretical performance, with a nominal oscillation frequency around 30 kHz, a sensitivity around 100 nT/Hz, and a noise floor around 50 nT. Several fabrication and assembly issues had to be solved in order to realize the device. The gap width of the capacitive structure is dependent on the thickness of the agent used to electrically connect the silicon anchor to a pad on a PCB. As it is desirable to minimize this gap width, some experimentation was required to find a suitable agent and assembly method. Additionally, the bonding agent used to attach the silicon anchor to the PCB must be applied at a temperature near the expected operating temperature of the device to prevent large stresses from being applied to the silicon frame due to the difference in the coefficients of thermal expansion between silicon and FR4. Also, during fabrication it was found that large flat areas, where a very uniform etch is critical, required wet KOH etching, while deep reactive ion etching could be used for areas where depth and a high aspect ratio were important. Significance This MEMS sensor represents a novel configuration for sensing magnetic fields. Without much optimization, the sensor already exceeds the sensitivity of many commercially available Hall-effect based MEMS magnetometers. As MEMS magnetometers are less developed than alternative magnetometer technologies, they may have more opportunities for improvement.

scholarly journals Collimated Bipolar Outflow and the Formation of Nuclear Spirals; Possible Role of Magnetic Fields

1990 ◽  
Vol 140 ◽  
pp. 447-448
Author(s):  
P. Pismis ◽  
E. Moreno ◽  
A. Garcia-Barreto
Keyword(s):  
Magnetic Fields ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Radio Galaxies ◽  
The Past ◽  
Bipolar Outflow ◽  
The Difference ◽  
Observational Techniques ◽  
Quasars And Radio Galaxies

The existence of non–steady phenomena, namely activity in the form of radial motions (outflow) of matter from the nuclei of galaxies is well established at present. Active Galactic Nuclei (AGN) constitute a topic of great interest and are intensively studied by all existing observational techniques. Conventionally objects classified as AGN span a range from quasars, radio galaxies to Seyferts 1 and 2. It appears, however, that there exist galaxies which exhibit somewhat milder activity which does not qualify their inclusion in the AGN group. The designation of MAGN (M for mildly) was suggested in the past (Pismis, 1986) to cover the less energetic nuclei. It may be reasonable to consider that active nuclei form a sequence, the difference along it being due to the energetics of the nuclei, from the most active quasars and radio galaxies down to the mildest ones like M31 or our Galaxy. The phenomenon underlying the activity may thus be universal, subject to the intrinsic energetics of the nuclei (Pismis, 1987).

Magneto-Spectroscopy of Two-Electron Transitions in Homoepitaxial GaN.

2001 ◽  
Vol 693 ◽  
Author(s):  
M. Wojdak ◽  
J.M. Baranowski ◽  
A. Wysmolck ◽  
K. Pakula ◽  
R. Stepnicwski ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Excited State ◽  
Magnetic Fields ◽  
Effective Mass ◽  
Electron Energy ◽  
Electron Transition ◽  
Electron Effective Mass ◽  
Neutral Donor ◽  
Electron Transitions ◽  
The Difference

AbstractTwo-electron transition occurs when the exciton bound to a neutral donor (DBE) recombines and leaves the donor in an excited state. The two-electron energy is therefore lower than that of the DBE peak by the difference in ground and excited state of the neutral donor. In a magnetic field the two-electron satellite splits into several components. These intra-donor excitations have been studied in homoepitaxial GaN up to magnetic fields reaching 23T. For Faraday (B‖c) configuration the two-electron transition splits mainly into 2s, 2p0, 2p+ and 2p- components. The total splitting between 2p+ and 2p- is equal to Landau energy. For Voigt (B???c) configuration in addition to transition to 2s, 2p0, 2p- and 2p+ there are additional lines which origin is discussed. It has been found that for two configurations of magnetic field the separation between 2p+ and 2p- is not exactly equal, what indicates the anisotropy of the electron effective mass. It has been found that m| = 0.205m0 and m??? = 0.225m0.

scholarly journals Strongly Magnetized Sources: QED and X-ray Polarization

Galaxies ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 76 ◽  
Author(s):  
Jeremy Heyl ◽  
Ilaria Caiazzo
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
First Principles ◽  
Quantum Electrodynamics ◽  
Polarization State ◽  
Radiative Corrections ◽  
Strong Magnetic Fields ◽  
X Ray ◽  
The Difference

Radiative corrections of quantum electrodynamics cause a vacuum threaded by a magnetic field to be birefringent. This means that radiation of different polarizations travels at different speeds. Even in the strong magnetic fields of astrophysical sources, the difference in speed is small. However, it has profound consequences for the extent of polarization expected from strongly magnetized sources. We demonstrate how the birefringence arises from first principles, show how birefringence affects the polarization state of radiation and present recent calculations for the expected polarization from magnetars and X-ray pulsars.

Study on the Solidification Structures of Al-Fe-Si Alloy under DC and AC Magnetic Fields

2011 ◽  
Vol 189-193 ◽  
pp. 4477-4482
Author(s):  
Chun Yan Ban ◽  
Xu Zhang ◽  
Peng Qian ◽  
Yi Han ◽  
Jian Zhong Cui
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Chinese Script ◽  
Minor Amount ◽  
Fine Needle ◽  
Ac Magnetic Field ◽  
Dc Magnetic Field ◽  
Conventional Condition ◽  
The Difference ◽  
Al Matrix

The effects of DC and AC magnetic field on the phase composition, morphology and distribution of the ternary Al-Fe-Si alloy were investigated. The solidification structures of the alloy solidified with and without the application of magnetic fields were confirmed by DSC and structural measurements. The results showed that, in this Al-Fe-Si alloy the fine needle-like Al3Fe phase dominated the microstructure at the grain boundaries with the minor amount of Chinese script-like α-AlFeSi. Distribution of Al3Fe phase was almost homogeneous in the volume of the sample when alloy was solidified in the conventional condition. When the DC magnetic field was imposed, distribution of Al3Fe phase was more homogeneous. However, the Al3Fe and α-AlFeSi phases were accumulated towards the center of the sample with the application of the AC magnetic field. This is due to the difference of Lorentz force between Al matrix and iron-containing intermetallics. Furthermore, the amount of Chinese script-like α-AlFeSi was increased remarkably under AC magnetic field.

Viscosity of a Polar Gas of Symmetric Top Molecules in Perpendicular Electric and Magnetic Fields

1978 ◽  
Vol 33 (2) ◽  
pp. 225-227 ◽  
Author(s):  
W. E. Köhler
Keyword(s):  
Magnetic Fields ◽  
Kinetic Theory ◽  
Electric Field ◽  
Electric Fields ◽  
Pressure Difference ◽  
Viscosity Coefficients ◽  
Electric And Magnetic Fields ◽  
Symmetric Top Molecules ◽  
Field Influence

A kinetic theory treatment of the influence of perpendicular magnetic and electric fields on the viscosity is given for a polar gas of symmetric top molecules. Expressions for the 9 independent viscosity coefficients are derived. In particular, the electric field influence on the transverse viscomagnetic pressure difference is studied.

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