An Alternative Operation Scheme to Improve the Efficiency of a Stark Decelerator

2021 ◽  
Vol 38 (12) ◽  
pp. 123201
Author(s):  
Mei Du ◽  
Dongdong Zhang ◽  
Dajun Ding
Keyword(s):  
High Voltage ◽  
Polar Molecules ◽  
Cold Molecules ◽  
Trajectory Simulation ◽  
Alternative Method ◽  
Order Of Magnitude ◽  
Focusing Property ◽  
Stark Decelerator

A Stark decelerator can slow down polar molecules to very low velocities. When the velocities are very low, the number of cold molecules obtained is very small. In order to obtain a higher quantity of cold molecules, inspired by the work of Reens et al. [Phys. Rev. Res. 2 (2020) 033 095], we propose an alternative method of operating a Stark decelerator. Through the trajectory simulation of OH molecules in the decelerator, we find that the number of cold molecules can be greatly increased by one order of magnitude at both low and high final velocities on a Stark decelerator consisting of around 150 electrodes. This development is due to the improved longitudinal and the transverse focusing property provided by the new switching schemes and the high-voltage configurations on the decelerator unit.

Surface modification of ZnO on the Zn-polar 0001 face by self-assembled triptycene-based polar molecules along with an increase of electric conductance

2022 ◽  
Author(s):  
Hiroki Shioya ◽  
Naoko Inoue ◽  
Masaro Yoshida ◽  
Yoshihiro IWASA
Keyword(s):  
Surface Modification ◽  
Critical Role ◽  
Polar Molecules ◽  
Hydroxyl Groups ◽  
Oxide Semiconductors ◽  
Assembled Monolayers ◽  
Temperature Dependences ◽  
Order Of Magnitude ◽  
Sheet Conductance ◽  
Self Assembled

Abstract Application of self-assembled monolayers (SAMs) is a representative method of surface modification for tuning material properties. In this study we examine the influence of the surface modification by coating the Zn-polar 0001 surface of ZnO single crystal with a SAM of triptycene-based polar molecules in our own technique and investigated temperature dependences of the sheet conductance of the surface with and without the SAM. The sheet conductance at 70 K with the SAM is increased by an order of magnitude, compared to the case without the SAM. We infer that the additional electrons are introduced at the surface by the polar triptycene molecules, whose electropositive hydroxyl groups are supposed to face toward the Zn-polar surface of ZnO. The present result implies that the molecular orientation of the triptycene SAM plays a critical role on the surface properties of oxide semiconductors.

scholarly journals Tailoring Adsorption Induced Switchability of a Pillared Layer MOF by Crystal Size Engineering

2020 ◽  
Author(s):  
Leila Abylgazina ◽  
Irena Senkovska ◽  
Sebastian Ehrling ◽  
Volodymyr Bon ◽  
Petko Petkov ◽  
...  
Keyword(s):  
Particle Size ◽  
Low Frequency ◽  
Polar Molecules ◽  
Adsorption Enthalpy ◽  
Factors Affecting ◽  
University Of Technology ◽  
Order Of Magnitude ◽  
Crystal Structural ◽  
Critical Particle Size ◽  
Characteristic Adsorption

The pillared layer framework DUT-8(Zn) (Zn<sub>2</sub>(2,6-ndc)<sub>2</sub>(dabco), 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicyclo-[2.2.2]-octane, DUT = Dresden University of Technology) is a prototypical switchable MOF, showing characteristic adsorption and desorption induced open phase (<i>op</i>) to closed phase (<i>cp</i>) transformation associated with huge changes in cell volume. We demonstrate switchability strongly depends on a framework-specific critical particle size (d<i><sub>crit</sub></i>). The solvent removal process (pore desolvation stress contracting the framework) significantly controls the <i>cp</i>/<i>op</i> ratio after desolvation and, subsequently, the adsorption induced switchability characteristics of the system. After desolvation, the dense <i>cp</i> phase of DUT-8(Zn) shows no adsorption-induced reopening and therefore is non-porous for N<sub>2</sub> at 77 K and CO<sub>2</sub> at 195 K. However, polar molecules with a higher adsorption enthalpy, such as the polar molecules such as chloromethane at 249 K and dichloromethane (DCM) at 298 K can reopen the macro-sized crystals upon adsorption. For macro-sized particles, the outer surface energy is negligible and only the type of metal (Zn, Co, Ni) controls the DCM-induced gate opening pressure. The framework stiffness increases from Zn to Ni as confirmed by DFT calculations, X-ray crystal structural analyses, and low frequency Raman spectroscopy. The partial disintegration of the Zn based node hinges produces an overall increased stabilization of<i> cp </i>vs. <i>op</i> phase shifts the critical particle size at which switchability starts to become suppressed to even lower values (d<i><sub>crit</sub></i> < 200 nm) as compared to the Ni-based system (<i>d<sub>crit</sub></i> ≈ 500 nm). Hence, the three factors affecting switchability (energetics of the empty host, (<i>E<sub>op</sub>-E<sub>cp</sub></i>) (I), particle size (II), and desolvation stress (III)) appear to be of the same order of magnitude and should be considered collectively, not individually.

Efficiency of High Voltage Transmission in Power Lines

2019 ◽  
Vol 01 (04) ◽  
pp. 1920009
Author(s):  
Ker Liang Goh
Keyword(s):  
High Voltage ◽  
Electrical Power ◽  
Introductory Physics ◽  
Power Lines ◽  
Power Station ◽  
Physics Courses ◽  
Alternative Method ◽  
High Voltage Transmission ◽  
Introductory Physics Courses

In introductory Physics courses, one might come across a question of why electricity is transmitted from the power station at high voltage? Analysis of a typical quantitative question is illustrated in this paper, showing its deficiencies. An alternative method that mimics more closely to realistic situations is proposed to better illustrate the increase in efficiency of transmitting electrical power at high voltages.

Multigrid, An Alternative Method for Calculating Film Thickness and Pressure Profiles in Elastohydrodynamically Lubricated Line Contacts

1986 ◽  
Vol 108 (4) ◽  
pp. 551-556 ◽  
Author(s):  
A. A. Lubrecht ◽  
W. E. ten Napel ◽  
R. Bosma
Keyword(s):  
Film Thickness ◽  
Multigrid Method ◽  
Computing Time ◽  
Alternative Method ◽  
Pressure Profiles ◽  
Minimum Film Thickness ◽  
Line Contacts ◽  
Pressure Spike ◽  
Order Of Magnitude

Film thickness and pressure profiles have been calculated for line contacts at moderate and high loads, using a Multigrid method. Influence of the compressibility of the lubricant on the minimum film thickness and on the pressure spike has been examined. The required computing time is an order of magnitude less than when using the previous methods.

scholarly journals Tailoring Adsorption Induced Switchability of a Pillared Layer MOF by Crystal Size Engineering

2020 ◽  
Author(s):  
Leila Abylgazina ◽  
Irena Senkovska ◽  
Sebastian Ehrling ◽  
Volodymyr Bon ◽  
Petko Petkov ◽  
...  
Keyword(s):  
Particle Size ◽  
Low Frequency ◽  
Polar Molecules ◽  
Adsorption Enthalpy ◽  
Factors Affecting ◽  
University Of Technology ◽  
Order Of Magnitude ◽  
Crystal Structural ◽  
Critical Particle Size ◽  
Characteristic Adsorption

The pillared layer framework DUT-8(Zn) (Zn<sub>2</sub>(2,6-ndc)<sub>2</sub>(dabco), 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicyclo-[2.2.2]-octane, DUT = Dresden University of Technology) is a prototypical switchable MOF, showing characteristic adsorption and desorption induced open phase (<i>op</i>) to closed phase (<i>cp</i>) transformation associated with huge changes in cell volume. We demonstrate switchability strongly depends on a framework-specific critical particle size (d<i><sub>crit</sub></i>). The solvent removal process (pore desolvation stress contracting the framework) significantly controls the <i>cp</i>/<i>op</i> ratio after desolvation and, subsequently, the adsorption induced switchability characteristics of the system. After desolvation, the dense <i>cp</i> phase of DUT-8(Zn) shows no adsorption-induced reopening and therefore is non-porous for N<sub>2</sub> at 77 K and CO<sub>2</sub> at 195 K. However, polar molecules with a higher adsorption enthalpy, such as the polar molecules such as chloromethane at 249 K and dichloromethane (DCM) at 298 K can reopen the macro-sized crystals upon adsorption. For macro-sized particles, the outer surface energy is negligible and only the type of metal (Zn, Co, Ni) controls the DCM-induced gate opening pressure. The framework stiffness increases from Zn to Ni as confirmed by DFT calculations, X-ray crystal structural analyses, and low frequency Raman spectroscopy. The partial disintegration of the Zn based node hinges produces an overall increased stabilization of<i> cp </i>vs. <i>op</i> phase shifts the critical particle size at which switchability starts to become suppressed to even lower values (d<i><sub>crit</sub></i> < 200 nm) as compared to the Ni-based system (<i>d<sub>crit</sub></i> ≈ 500 nm). Hence, the three factors affecting switchability (energetics of the empty host, (<i>E<sub>op</sub>-E<sub>cp</sub></i>) (I), particle size (II), and desolvation stress (III)) appear to be of the same order of magnitude and should be considered collectively, not individually.

scholarly journals An alternative method for measuring velocities in open-channel flows: perfomance evaluation of a Pitot tube compared to an acoustic meter

RBRH ◽  
2017 ◽  
Vol 22 (0) ◽  
Author(s):  
Arlan Scortegagna Almeida ◽  
Vladimir Caramori Borges de Souza
Keyword(s):  
Open Channel ◽  
Channel Flows ◽  
Pitot Tube ◽  
Reasonable Accuracy ◽  
Open Channel Flows ◽  
Velocity Fluctuations ◽  
Alternative Method ◽  
Total Head ◽  
Order Of Magnitude ◽  
The Mean

ABSTRACT Hydrometric measurements undertaken in channels with high velocities are conditioned to the particularities of the flow, which is often characterized by instantaneous fluctuations and disturbances on the free surface. In such cases, the uncertainties associated with velocity fluctuations exceed the precision offered by the instruments that are employed in conventional techniques. A reasonable accuracy of the results is therefore sufficient to accomplish the objective of the measurements. The use of devices based on Pitot’s principle in fast open-channel flows could be an effective alternative to conventional velocity meters. This study aimed to develop a Pitot tube in its simplest configuration and evaluate its performance in a laboratory channel at velocities ranging from 0.2 to 2.0 m/s. The uncertainties in the static and total head readings were propagated to the output velocities, showing that the device built has the potential for measurements over 1.2 m/s, but it is not recommended for low velocities (<0.6 m/s). The results were compared to those taken using an Acoustic Doppler Velocimeter (ADV). The instantaneous velocity readings indicated uncertainties of the same order of magnitude in both instruments. The differences between the mean velocities measured by the Pitot tube and the ADV were restricted to an agreement range of 15%, which is expected to be gradually reduced with further increase in flow velocity. The results showed the similar performances of both devices regarding the higher velocity estimates. Therefore, velocity meters should be developed to employ Pitot devices as an alternative method in high-velocity open-channel flows.

scholarly journals Characterization of Anomalous Forces in Dielectric Rotors

2021 ◽  
Author(s):  
Elio B. Porcelli ◽  
Victo S. Filho
Keyword(s):  
Theoretical Model ◽  
Angular Velocity ◽  
High Voltage ◽  
Weight Reduction ◽  
Counterclockwise Rotation ◽  
Order Of Magnitude ◽  
Experimental Findings ◽  
Magnetic Case ◽  
Made In

We performed several measurements of anomalous forces on a dielectric rotor under electrostatic conditions of operation. The device operated under constant and intense angular velocity for each high voltage applied. The measurements were made in the similar way than an analogue magnetic gyroscope, by considering clockwise and counterclockwise rotations. We found that there are significant weight reduction on the device in the clockwise case, with one order of magnitude higher than the magnetic case. In addition, we detected a similar asymmetry in the observation of the effect, that is, there are smaller results for the anomalous forces in counterclockwise rotation for higher values of the voltage applied on the device. We also propose a theoretical model to explain the quantitative effect based on average values of macroscopic observables of the device rotation and concluded that it is consistent with the experimental findings.

Concentrated mixed cation acetate “water-in-salt” solutions as green and low-cost high voltage electrolytes for aqueous batteries

2018 ◽  
Vol 11 (10) ◽  
pp. 2876-2883 ◽  
Author(s):  
Maria R. Lukatskaya ◽  
Jeremy I. Feldblyum ◽  
David G. Mackanic ◽  
Franziska Lissel ◽  
Dominik L. Michels ◽  
...  
Keyword(s):  
High Voltage ◽  
Low Cost ◽  
Soluble Salts ◽  
Salt Solutions ◽  
Alkali Cations ◽  
Mixed Cation ◽  
Order Of Magnitude ◽  
Aqueous Batteries

Challenge of developing new formulations of water-in-salt electrolytes are addressedviamixed cation strategy: cheaper (by at least an order of magnitude) and more soluble salts featuring alkali cations beyond lithium, such as potassium, are used to create the water-in-salt condition.

scholarly journals Optimizing the Stark-decelerator beamline for the trapping of cold molecules using evolutionary strategies

2006 ◽  
Vol 73 (6) ◽  
Author(s):  
Joop J. Gilijamse ◽  
Jochen Küpper ◽  
Steven Hoekstra ◽  
Nicolas Vanhaecke ◽  
Sebastiaan Y. T. van de Meerakker ◽  
...  
Keyword(s):  
Evolutionary Strategies ◽  
Cold Molecules ◽  
Stark Decelerator
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