scholarly journals Effects of long-range tip-sample interaction on magnetic force imaging: A comparative study between bimorph driven system and electrostatic force modulation

2012 ◽  
Vol 111 (10) ◽  
pp. 104313 ◽  
Author(s):  
Byung I. Kim
Keyword(s):  
Comparative Study ◽  
Long Range ◽  
Magnetic Force ◽  
Electrostatic Force ◽  
Force Modulation ◽  
Driven System

scholarly journals Distinguishing magnetic and electrostatic interactions by a Kelvin probe force microscopy–magnetic force microscopy combination

2011 ◽  
Vol 2 ◽  
pp. 552-560 ◽  
Author(s):  
Miriam Jaafar ◽  
Oscar Iglesias-Freire ◽  
Luis Serrano-Ramón ◽  
Manuel Ricardo Ibarra ◽  
Jose Maria de Teresa ◽  
...  
Keyword(s):  
Long Range ◽  
Electrostatic Interaction ◽  
Electrostatic Interactions ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Superparamagnetic Nanoparticles ◽  
Kelvin Probe Force Microscopy ◽  
Magnetic Interactions ◽  
Kelvin Probe ◽  
Force Microscopy

The most outstanding feature of scanning force microscopy (SFM) is its capability to detect various different short and long range interactions. In particular, magnetic force microscopy (MFM) is used to characterize the domain configuration in ferromagnetic materials such as thin films grown by physical techniques or ferromagnetic nanostructures. It is a usual procedure to separate the topography and the magnetic signal by scanning at a lift distance of 25–50 nm such that the long range tip–sample interactions dominate. Nowadays, MFM is becoming a valuable technique to detect weak magnetic fields arising from low dimensional complex systems such as organic nanomagnets, superparamagnetic nanoparticles, carbon-based materials, etc. In all these cases, the magnetic nanocomponents and the substrate supporting them present quite different electronic behavior, i.e., they exhibit large surface potential differences causing heterogeneous electrostatic interaction between the tip and the sample that could be interpreted as a magnetic interaction. To distinguish clearly the origin of the tip–sample forces we propose to use a combination of Kelvin probe force microscopy (KPFM) and MFM. The KPFM technique allows us to compensate in real time the electrostatic forces between the tip and the sample by minimizing the electrostatic contribution to the frequency shift signal. This is a great challenge in samples with low magnetic moment. In this work we studied an array of Co nanostructures that exhibit high electrostatic interaction with the MFM tip. Thanks to the use of the KPFM/MFM system we were able to separate the electric and magnetic interactions between the tip and the sample.

scholarly journals Electrostatic forces alter particle size distributions in atmospheric dust

2020 ◽  
Vol 20 (5) ◽  
pp. 3181-3190 ◽  
Author(s):  
Joseph R. Toth III ◽  
Siddharth Rajupet ◽  
Henry Squire ◽  
Blaire Volbers ◽  
Jùn Zhou ◽  
...  
Keyword(s):  
Electric Field ◽  
Size Distribution ◽  
Long Range ◽  
Electric Fields ◽  
Electrostatic Force ◽  
Small Scale ◽  
Size Distributions ◽  
Electrostatic Forces ◽  
Atmospheric Dust ◽  
Airborne Dust

Abstract. Large amounts of dust are lofted into the atmosphere from arid regions of the world before being transported up to thousands of kilometers. This atmospheric dust interacts with solar radiation and causes changes in the climate, with larger-sized particles having a heating effect, and smaller-sized particles having a cooling effect. Previous studies on the long-range transport of dust have found larger particles than expected, without a model to explain their transport. Here, we investigate the effect of electric fields on lofted airborne dust by blowing sand through a vertically oriented electric field, and characterizing the size distribution as a function of height. We also model this system, considering the gravitational, drag, and electrostatic forces on particles, to understand the effects of the electric field. Our results indicate that electric fields keep particles suspended at higher elevations and enrich the concentration of larger particles at higher elevations. We extend our model from the small-scale system to long-range atmospheric dust transport to develop insights into the effects of electric fields on size distributions of lofted dust in the atmosphere. We show that the presence of electric fields and the resulting electrostatic force on charged particles can help explain the transport of unexpectedly large particles and cause the size distribution to become more uniform as a function of elevation. Thus, our experimental and modeling results indicate that electrostatic forces may in some cases be relevant regarding the effect of atmospheric dust on the climate.

scholarly journals Torque characteristics of double-stator permanent magnet synchronous machines

2017 ◽  
Vol 66 (4) ◽  
pp. 815-828
Author(s):  
Chukwuemeka Chijioke Awah ◽  
Ogbonnaya Inya Okoro
Keyword(s):  
Comparative Study ◽  
Permanent Magnet ◽  
Magnetic Force ◽  
Fault Tolerant ◽  
Synchronous Machine ◽  
Synchronous Machines ◽  
Permanent Magnet Synchronous Machines ◽  
Rotor Position ◽  
Rotor Pole ◽  
Static Torque

Abstract The torque profile of a double-stator permanent magnet (PM) synchronous machine of 90 mm stator diameter having different rotor pole numbers as well as dual excitation is investigated in this paper. The analysis includes a comparative study of the machine’s torque and power-speed curves, static torque and inductance characteristics, losses and unbalanced magnetic force. The most promising flux-weakening potential is revealed in 13- and 7-rotor pole machines. Moreover, the machines having different rotor/stator (Nr/Ns) pole combinations of the form Nr = Ns ± 1 have balanced and symmetric static torque waveforms variation with the rotor position in contrast to the machines having Nr = Ns ± 2. Further, the inductance results of the analyzed machines reveal that the machines with odd rotor pole numbers have better fault-tolerant capability than their even rotor pole equivalents. A prototype of the developed double-stator machine having a 13-pole rotor is manufactured and tested for verification.

Fast Electrostatic Force and Moment Calculations in Multibody-Based Simulations of Coarse-Grained Biopolymers

2011 ◽  
Author(s):  
Mohammad Poursina ◽  
Jeremy Laflin ◽  
Kurt S. Anderson
Keyword(s):  
Force Field ◽  
Long Range ◽  
Electrostatic Force ◽  
Center Of Mass ◽  
Computational Cost ◽  
Field Approximation ◽  
The Body ◽  
Divide And Conquer ◽  
Coarse Grained ◽  
Coarse Grain

In molecular simulations, the dominant portion of the computational cost is associated with force field calculations. Herein, we extend the approach used to approximate long range gravitational force and the associated moment in spacecraft dynamics to the coulomb forces present in coarse grained biopolymer simulations. We approximate the resultant force and moment for long-range particle-body and body-body interactions due to the electrostatic force field. The resultant moment approximated here is due to the fact that the net force does not necessarily act through the center of mass of the body (pseudoatom). This moment is considered in multibody-based coarse grain simulations while neglected in bead models which use particle dynamics to address the dynamics of the system. A novel binary divide and conquer algorithm (BDCA) is presented to implement the force field approximation. The proposed algorithm is implemented by considering each rigid/flexible domain as a node of the leaf level of the binary tree. This substructuring strategy is well suited to coarse grain simulations of chain biopolymers using an articulated multibody approach.

scholarly journals Electrostatic attraction caused by triboelectrification in climbing geckos

Friction ◽  
2020 ◽  
Author(s):  
Yi Song ◽  
Zhouyi Wang ◽  
Yang Li ◽  
Zhendong Dai
Keyword(s):  
Long Range ◽  
Capillary Force ◽  
Electrostatic Force ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Electrostatic Attraction ◽  
Distance Range ◽  
Hybrid Mechanism ◽  
Adhesion Model ◽  
Gecko Adhesion

Abstract Adhesion achieved through feet setae is fundamental for gecko agilely maneuvering. Although diverse hypotheses have been proposed, none of them thoroughly explains the setae function, implying a kind of hybrid-mechanism-based adhesion in geckos. In addition to van der Waals interactions and capillary force, the electrostatic attraction that emerges from triboelectrification was suggested as a component of setae adhesion. Nevertheless, the contribution by electrostatic attraction to the total setae attachment is still controversial. In this study, we analyzed the occurrence of electrostatic attraction at gecko setae through experiments and model analyses. By touching the substrates with only ∼1/70th of the foot area, freely wall-climbing geckos developed tribocharge at their feet setae with a density of ∼277 pC/mm2, generating electrostatic attractions with a strength of ∼4.4 mN/mm2. From this perspective, the adhesion driven by triboelectrification could account for about 1% of total adhesion. Model analyses at spatula level indicated a similar result showing that the electrostatic force might account for ∼3% of the adhesion that facilitates wall-climbing in geckos. The low contribution of the electrostatic force partly explains why geckos always face difficulty in maneuvering onto those substrates (e.g., teflon) where they could easily develop tribocharge but difficultly generate van der Waals force. However, long-range electrostatic forces may play other roles in a distance range where the van der Waals interaction cannot function. These findings not only add to our understanding of the mechanism of gecko adhesion, but also will help us advance gecko-inspired fibular adhesives.

scholarly journals Electrostatic forces alter particle size distributions in atmospheric dust

2019 ◽  
Author(s):  
Joseph R. Toth III ◽  
Siddharth Rajupet ◽  
Henry Squire ◽  
Blaire Volbers ◽  
Jùn Zhou ◽  
...  
Keyword(s):  
Electric Field ◽  
Size Distribution ◽  
Long Range ◽  
Electric Fields ◽  
Electrostatic Force ◽  
Small Scale ◽  
Size Distributions ◽  
Electrostatic Forces ◽  
Atmospheric Dust ◽  
Airborne Dust

Abstract. Large amounts of dust are lofted into the atmosphere from arid regions of the world before being transported up to thousands of kilometers. This atmospheric dust interacts with solar radiation causing changes in the climate, with larger-sized particles having a heating effect, and smaller-sized particles having a cooling effect. Previous studies on the long-range transport of dust have found larger particles than expected, without a model to explain their transport. Here, we investigate the effect of electric fields on lofted airborne dust by blowing sand through a vertically-oriented electric field, and characterizing the size distribution as a function of height. We also model this system, considering the gravitational, drag, and electrostatic forces on particles, to understand the effects of the electric field. Our results indicate that electric fields keep particles suspended at higher elevations and enrich the concentration of larger particles at higher elevations. We extend our model from the small-scale system to long-range atmospheric dust transport to develop insights on the effects of electric fields on size distributions of lofted dust in the atmosphere. We show that the presence of electric fields and the resulting electrostatic force on particles can help explain the transport of unexpectedly larger particles and cause the size distribution to become more uniform as a function of elevation. Thus, our experimental and modelling results indicate that electrostatic forces should be considered when determining the effect of atmospheric dust on the climate.

Molecular Simulation of Electrokinetic Transport in Nanofluidics

2009 ◽  
Author(s):  
Jin Liu ◽  
Moran Wang ◽  
Shiyi Chen ◽  
Mark O. Robbins
Keyword(s):  
Long Range ◽  
Electrostatic Force ◽  
Physical Space ◽  
Electrokinetic Transport ◽  
Biomedical Analysis ◽  
Electrowetting On Dielectric ◽  
Coulombic Interactions ◽  
Potential Applications ◽  
Energy Conversion Systems ◽  
Grid Technique

Electrokinetic transport in nanofluidics has attracted many attentions in recent years due to its potential applications in biomedical analysis and energy conversion systems. The biggest challenge to model the electrokinetic transport using atomistic simulations is the extensive cost in calculation of the long-range electrostatic force between ions. In this work, we develop an efficient molecular approach to simulate electrokinetic transport in nano-scale. The long-range Coulombic interactions are treated using the Particle-Particle Particle-Mesh (P3M) scheme and the Poisson equation for electric potential is solved in physical space using an iterative multi-grid technique. We implement this approach to systematically investigate two examples: the electroosmotic flow in random rough channels and the electrowetting on dielectric (EWOD). Both cases pose important engineering applications as a mechanism for transporting small amount of liquid in micro and nano devices.

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