Rotational Dynamics of Desorption: Methane and Ethane at Stepped and Kinked Platinum Surfaces

2021 ◽  
Author(s):  
Sabine C. Matysik ◽  
David J. Wales ◽  
Stephen J. Jenkins
Keyword(s):  
Rotational Dynamics ◽  
Platinum Surfaces

Ultrathin Platinum Crystal Surface Structures

1985 ◽  
Vol 43 ◽  
pp. 394-395
Author(s):  
R. L. Hines
Keyword(s):  
Crystal Surface ◽  
Surface Structures ◽  
Platinum Surface ◽  
Platinum Surfaces ◽  
Resolution Level ◽  
Experimental Facilities ◽  
Carbon Backing ◽  
Mesh Grid ◽  
Atom Layer

The importance of atom layer terraces or steps on platinum surfaces used for catalysis as discussed by Somorjai justifies an extensive investigation of the structure of platinum surfaces through electron microscopy at the atomic resolution level. Experimental and theoretical difficulties complicate the quantitative determination of platinum surface structures but qualitative observation of surface structures on platinum crystals is now possible with good experimental facilities.Ultrathin platinum crystals with nominal 111 orientation are prepared using the procedure reported by Hines without the application of a carbon backing layer. Platinum films with thicknesses of about ten atom layers are strong enough so that they can be mounted on grids to provide ultrathin platinum crystals for examination of surface structure. Crystals as thin as possible are desired to minimize the theoretical difficulties in analyzing image contrast to determine structure. With the current preparation procedures the crystals frequently cover complete openings on a 400 mesh grid.

Introductory Rotational Dynamics

2018 ◽  
Author(s):  
Peter Mann
Keyword(s):  
Angular Momentum ◽  
Angular Displacement ◽  
Rigid Bodies ◽  
Rotational Dynamics ◽  
Circular Motion ◽  
Uniform Rotation ◽  
Chemical Systems ◽  
Inertial Frames ◽  
Rotating Frames ◽  
Special Case

This chapter discusses the importance of circular motion and rotations, whose applications to chemical systems are plentiful. Circular motion is the book’s first example of a special case of motion using the laws developed in previous chapters. The chapter begins with the basic definitions of circular motion; as uniform rotation around a principle axis is much easier to consider, it is the focus of this chapter and is used to develop some key ideas. The chapter discusses angular displacement, angular velocity, angular momentum, torque, rigid bodies, orbital and spin momenta, inertia tensors and non-inertial frames and explores fictitious forces as well as transformations in rotating frames.

scholarly journals Modeling and Analysis of a Generic Internal Cargo Airdrop System for a Tandem Helicopter

2021 ◽  
Vol 11 (11) ◽  
pp. 5109
Author(s):  
Guozhi Li ◽  
Yihua Cao ◽  
Maosheng Wang
Keyword(s):  
Nonlinear Dynamics ◽  
Flight Dynamics ◽  
Simulation Method ◽  
Rotational Dynamics ◽  
Discretization Method ◽  
Modeling And Analysis ◽  
Flight Velocity ◽  
Vector Mechanics ◽  
Good Attitude

This article describes the results of modeling and analysis of a generic internal cargo system using a discretization method of the vector mechanics. The model can be easily incorporated into a tandem helicopter model and is intended for use of simulation and investigating the problems of flight dynamics, control, etc., both in flight operation loading a cargo and flight operation in the process of airdrops. The model is derived by considering the main descriptions of the cargo, including the linear and rotational dynamics, the kinematics, and the forces and moments acting on the helicopter. A simulation method embedded with a numerical trim algorithm is developed for the complete coupling helicopter/cargo nonlinear dynamics system. The simulation application of the model is illustrated, including the case of flight operation loading a cargo by considering three mass configurations of 3000, 4500, and 6000 kg, and the case of flight operation in the process of airdrops at velocities of 0, 40, 80, 120, and 160 knots. Stabilities of the helicopter in the process of airdrops are also analyzed. The major conclusions drawn are: (i) the tandem helicopter has a good attitude maintaining ability in the whole flight velocity envelope when it conducts a flight operation loading a cargo; (ii) in the process of airdrops, the increase in flight velocity will constantly decrease the helicopter pitching attitude and increases the total airdrop time and decreases the backward moving velocity of the cargo, and helicopter flying at a velocity between 80 and 120 knots might be acceptable; (iii) the stabilities of both the longitudinal and lateral periodic modes are continuing to decrease during the backward movement of the cargo.

Breathing Effect via Solvent Inclusions on the Linker Rotational Dynamics of Functionalized MIL‐53

2021 ◽  
Author(s):  
Jing Tang ◽  
Yueying Chu ◽  
Shenhui Li ◽  
Jun Xu ◽  
Wenpeng Xiong ◽  
...  
Keyword(s):  
Rotational Dynamics

Contrasting Effects of FA Substitution on MA/FA Rotational Dynamics in FAxMA1–xPbI3

2021 ◽  
Author(s):  
V. K. Sharma ◽  
R. Mukhopadhyay ◽  
A. Mohanty ◽  
V. García Sakai ◽  
M. Tyagi ◽  
...  
Keyword(s):  
Rotational Dynamics

Insights into the translational and rotational dynamics of cations and anions in protic ionic liquids by means of NMR fast-field-cycling relaxometry

2021 ◽  
Vol 23 (4) ◽  
pp. 2663-2675
Author(s):  
Viviane Overbeck ◽  
Henning Schröder ◽  
Anne-Marie Bonsa ◽  
Klaus Neymeyr ◽  
Ralf Ludwig
Keyword(s):  
Ionic Liquids ◽  
Rotational Dynamics ◽  
Protic Ionic Liquids ◽  
Field Cycling ◽  
Fast Field ◽  
Hydrogen Bonded

NMR Fast-Field-Cycling (FFC) relaxometry provides important information about translational and rotational dynamics of hydrogen bonded protic ionic liquids (PILs). 

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