scholarly journals Transition between Random and Periodic Electron Currents on a DNA Chain

2021 ◽  
Vol 22 (14) ◽  
pp. 7361
Author(s):  
Elham Faraji ◽  
Roberto Franzosi ◽  
Stefano Mancini ◽  
Marco Pettini
Keyword(s):  
Frequency Spectrum ◽  
External Source ◽  
Electron Excitation ◽  
Dynamical Equations ◽  
Heavy Particles ◽  
Model Hamiltonian ◽  
External Electromagnetic Fields ◽  
Dna Chain ◽  
Dna Fragment ◽  
A Chain

By resorting to a model inspired to the standard Davydov and Holstein-Fröhlich models, in the present paper we study the motion of an electron along a chain of heavy particles modeling a sequence of nucleotides proper to a DNA fragment. Starting with a model Hamiltonian written in second quantization, we use the Time Dependent Variational Principle to work out the dynamical equations of the system. It can be found that, under the action of an external source of energy transferred to the electron, and according to the excitation site, the electron current can display either a broad frequency spectrum or a sharply peaked frequency spectrum. This sequence-dependent charge transfer phenomenology is suggestive of a potentially rich variety of electrodynamic interactions of DNA molecules under the action of electron excitation. This could imply the activation of interactions between DNA and transcription factors, or between DNA and external electromagnetic fields.

Dynamics of Constrained Multibody Systems

1984 ◽  
Vol 51 (4) ◽  
pp. 899-903 ◽  
Author(s):  
J. W. Kamman ◽  
R. L. Huston
Keyword(s):  
Multibody Systems ◽  
Equations Of Motion ◽  
Governing Equations ◽  
Dynamical Equations ◽  
Closed Loops ◽  
Constrained Multibody Systems ◽  
Constraint Equations ◽  
Cable Dynamics ◽  
Hanging Chain ◽  
A Chain

A new automated procedure for obtaining and solving the governing equations of motion of constrained multibody systems is presented. The procedure is applicable when the constraints are either (a) geometrical (for example, “closed-loops”) or (b) kinematical (for example, specified motion). The procedure is based on a “zero eigenvalues theorem,” which provides an “orthogonal complement” array which in turn is used to contract the dynamical equations. This contraction, together with the constraint equations, forms a consistent set of governing equations. An advantage of this formulation is that constraining forces are automatically eliminated from the analysis. The method is applied with Kane’s equations—an especially convenient set of dynamical equations for multibody systems. Examples of a constrained hanging chain and a chain whose end has a prescribed motion are presented. Applications in robotics, cable dynamics, and biomechanics are suggested.

Effects of vehicle driveline parameters and clutch judder on gearbox vibrations

2021 ◽  
pp. 095440702110159
Author(s):  
Ali Hajnayeb ◽  
Joseph S Fernando ◽  
Qiao Sun
Keyword(s):  
Experimental Data ◽  
Modal Analysis ◽  
Frequency Spectrum ◽  
Spectrum Analysis ◽  
Dynamical Equations ◽  
Frequency Spectrum Analysis ◽  
Undesirable Event ◽  
Frequency Components ◽  
Loss Of Contact ◽  
Dry Clutch

Clutch judder causes discomfort in a car. This undesirable event not only creates noise and vibrations, it also disturbs the normal functionality of other components in the driveline, especially the gearbox, which is prone to oscillating inputs. Although there are numerous separate studies on clutch judder and gearbox vibrations, a combined study is necessary in order to investigate the coupled dynamics, especially the effect of vibrations in a clutch on gearbox vibrations. In this paper, a dynamic model is presented for the driveline, including the details of a gearbox and a dry clutch. It allows us to investigate the effect of clutch parameters and to simulate conditions with and without judder. The obtained dynamical equations are then solved numerically. The influence of judder on gear dynamics and passenger comfort is investigated. The results show that judder causes loss of contact in the gearbox in most cases. In more severe cases of judder, it can cause rattle not only in the unloaded gear, but also in the loaded gears. A modal analysis and a frequency spectrum analysis are conducted as well in order to identify the frequency components of the system vibrations and to verify the obtained results. Parts of the results are compared with the theoretical and experimental data from other research studies, which show agreement and serve to validate the model in this work.

A Mathematical Model for Studying the Pulse Flaw Detection of High-Voltage Transformer Windings

2021 ◽  
pp. 50-57
Author(s):  
Alexey V. LAVRINOVICH ◽  
◽  
Alexey V. MYTNIKOV ◽  
Keyword(s):  
Mathematical Model ◽  
Frequency Spectrum ◽  
Low Voltage ◽  
Power Transformer ◽  
Flaw Detection ◽  
Pulse Frequency ◽  
Voltage Transformer ◽  
Nanosecond Pulses ◽  
Transformer Winding ◽  
A Chain

The article presents the results from elaborating a power transformer mathematical model for modeling the processes of diagnosing the mechanical state of windings using the method of low-voltage nanosecond pulses. The model includes a chain representation of the transformer windings taking into account the dependence of the resistance and reactance of the turns on the frequency spectrum of the pulse supplied from the probing generator. The study of the pulse flaw detection processes carried out on the developed mathematical model has shown that the probing pulse frequency spectrum plays an essential role in locating the transformer winding flaw, in determining the flaw type (displacement of turns, inward radial displacement, buckling). The response signals obtained from application of the simulated probing pulse coincide satisfactorily with the response signals obtained during experiments on the transformer physical model. The developed model opens the possibility of determining, by calculation, transformer winding flaw location and type based on comparing the results of experimental responses during examinations of transformers using the method of low-voltage nanosecond pulses with the simulation results.

FOLDING DYNAMICS IN A SEMIFLEXIBLE POLYMER AS A MODEL OF DNA

2002 ◽  
Vol 12 (09) ◽  
pp. 2003-2008 ◽  
Author(s):  
HIROSHI NOGUCHI
Keyword(s):  
Brownian Dynamics ◽  
Metastable States ◽  
Dynamics Simulation ◽  
Duplex Dna ◽  
Brownian Dynamics Simulation ◽  
Discrete Transition ◽  
Semiflexible Polymer ◽  
Folding Dynamics ◽  
Dna Chain ◽  
A Chain

We studied the folding transition of a semiflexible homopolymer chain using a Brownian dynamics simulation. A duplex DNA chain exhibits a discrete transition between an elongated coil state and a folded state with toroidal morphology. We show that these folding properties are understood with the stiffness of DNA chains. Semiflexible chains fold through various paths into collapsed toroidal states stochastically. Some chains fold directly by winding around a ring along a chain. Others fold through rod states, which are kinetically trapped metastable states.

scholarly journals The intensity distribution in the nitrogen band systems emitted from the earth’s upper atmosphere

1949 ◽  
Vol 196 (1045) ◽  
pp. 217-250 ◽  
Keyword(s):  
Intensity Distribution ◽  
Vibrational Temperature ◽  
Direct Action ◽  
Preliminary Investigation ◽  
Electron Excitation ◽  
Positive System ◽  
Heavy Particles ◽  
Degree Of Dissociation ◽  
Negative Band ◽  
High Degree

The intensity distributions in the negative and first and second positive band systems of nitrogen are determined for a number of excitation mechanisms. The results are compared with the intensity distributions observed from upper atmospheric sources with a view to understanding the processes occurring. Ordinary aurorae are discussed in detail. It is shown that if the emission is attributed to electron excitation (as is commonly done) then it is necessary to assume that the vibrational temperature of the molecules is many thousands of degrees absolute—as similar views have been expressed by earlier writers on evidence that is now discredited it may be mentioned that in the present paper proper account is taken of the Frank-Condon principle. A more plausible interpretation of the observational results is that the heavy particles, that are often considered to form part of incident auroral streams, contribute to the excitation. High and low latitude aurorae show striking differences. The emission of the negative band system from sunlit aurorae and from the twilight sky is studied. The direct action of the solar radiation on nitrogen ions is responsible. In the case of sunlit aurorae the continued absorption and emission of the resonance bands raises the vibrational temperature of the ions: this greatly influences the intensity distribution. The consequences of the identification of the strong infra-red emission from the nocturnal sky with the (0, 0) band of the first positive system is discussed. It would appear that the identification necessitates a high degree of dissociation of the upper atmospheric nitrogen. Confirmatory observational work is urged. In the appendix a preliminary investigation on the energy distribution of electrons inaurorae is attempted

Investigation of 3:1 Internal Resonance of Electrostatically Actuated Microbeams With Flexible Supports

2020 ◽  
Author(s):  
Praveen Kumar ◽  
Mandar M. Inamdar ◽  
Dnyanesh N. Pawaskar
Keyword(s):  
Internal Resonance ◽  
Multiple Scales ◽  
Time Integration ◽  
External Source ◽  
Mems Devices ◽  
Electrode Gap ◽  
Dynamical Equations ◽  
Electrostatically Actuated ◽  
Second Mode ◽  
Flexible Supports

Abstract Interaction between modes due to internal resonance has many applications in MEMS devices. In this paper, we investigate the modal interaction through 3 : 1 internal resonance of an electrostatically actuated microbeam with flexible supports in the form of rotational and transversal springs. The static displacement and the first three modal frequencies are obtained at the applied DC voltage by a reduced order model for a specified ratio of electrode gap and thickness. We then obtain the value of applied voltage for which 3 : 1 internal resonance exists for four different combinations of unequal end support stiffnesses. We calculate the coefficients of the coupled dynamical equations of first two modes for all the four cases and solve them by using numerical time integration and the method of multiple scales. We observe the interaction between the first and the second mode when each of the modes is independently excited by an external source. When the second mode is externally excited, interestingly, we also find that the undriven mode response amplitude is twice that of the driven mode.

scholarly journals USING PROMPT NEUTRON DECAY CONSTANT MEASUREMENTS TO OBTAIN ADDITIONAL KINETICS INFORMATION

2021 ◽  
Vol 247 ◽  
pp. 09024
Author(s):  
George McKenzie ◽  
Travis Grove ◽  
Jesson Hutchinson
Keyword(s):  
Decay Constant ◽  
External Source ◽  
Prompt Neutron ◽  
Neutron Decay ◽  
System Of Equations ◽  
Neutron Lifetime ◽  
Unknown Parameters ◽  
Single Experiment ◽  
Detector Geometry ◽  
A Chain

Prompt neutron decay constant measurements are typically used to infer the prompt neutron lifetime in a chain-reacting system, but these measurements include much more information about the kinetics of the system. This work focuses specifically on the Rossi-α method of measuring the prompt neutron decay constant. The Rossi-α system of equations consists of five unknown parameters. With five unknowns and three equations, the system of equations solved by the Rossi-α measurement is under-determined. It has been postulated that a well posed problem can be formulated using independent measurement configurations on a single system. The external source strength, the effective delayed neutron fractions, and Diven’s parameter do not typically change for different configurations of a single experiment. If good detector geometry is chosen, the detector efficiency does not change for multiple measurements of a single experiment using Rossi-α measurements. By making these assumptions, there are only two unique variables. This knowledge can be used to solve for most of the unique parameters using two independent, unique Rossi-α measurements.

Application of Modified Bloch Waves to Image Analysis of Extended Linear Defects

1974 ◽  
Vol 32 ◽  
pp. 402-403
Author(s):  
S. Nakahara ◽  
D. M. Maher
Keyword(s):  
Image Analysis ◽  
Computational Approach ◽  
Dislocation Loops ◽  
Plane Wave Expansion ◽  
Dynamical Equations ◽  
Bloch Waves ◽  
Linear Defects ◽  
Imperfect Crystal ◽  
Localized Defects ◽  
Defective Crystals

Since Head first demonstrated the advantages of computer displayed theoretical intensities from defective crystals, computer display techniques have become important in image analysis. However the computational methods employed resort largely to numerical integration of the dynamical equations of electron diffraction. As a consequence, the interpretation of the results in terms of the defect displacement field and diffracting variables is difficult to follow in detail. In contrast to this type of computational approach which is based on a plane-wave expansion of the excited waves within the crystal (i.e. Darwin representation ), Wilkens assumed scattering of modified Bloch waves by an imperfect crystal. For localized defects, the wave amplitudes can be described analytically and this formulation has been used successfully to predict the black-white symmetry of images arising from small dislocation loops.

Observation of Atom Rows in Thorium Pyromellitate Using a Field Emission STEM

1977 ◽  
Vol 35 ◽  
pp. 80-81
Author(s):  
H. Todokoro ◽  
S. Nomura ◽  
T. Komoda
Keyword(s):  
Field Emission ◽  
Amorphous Carbon ◽  
Carbon Film ◽  
Dark Field Image ◽  
Dark Field ◽  
Amorphous Carbon Film ◽  
Atomic Size ◽  
Wide Range ◽  
A Chain

It is interesting to observe polymers at atomic size resolution. Some works have been reported for thorium pyromellitate by using a STEM (1), or a CTEM (2,3). The results showed that this polymer forms a chain in which thorium atoms are arranged. However, the distance between adjacent thorium atoms varies over a wide range (0.4-1.3nm) according to the different authors.The present authors have also observed thorium pyromellitate specimens by means of a field emission STEM, described in reference 4. The specimen was prepared by placing a drop of thorium pyromellitate in 10-3 CH3OH solution onto an amorphous carbon film about 2nm thick. The dark field image is shown in Fig. 1A. Thorium atoms are clearly observed as regular atom rows having a spacing of 0.85nm. This lattice gradually deteriorated by successive observations. The image changed to granular structures, as shown in Fig. 1B, which was taken after four scanning frames.

Influence of X-Ray Induced Fluorescence on Energy Dispersive X-Ray Analysis of Thin Foils

1977 ◽  
Vol 35 ◽  
pp. 328-329
Author(s):  
E. A. Kenik ◽  
J. Bentley
Keyword(s):  
Thin Foil ◽  
Electron Excitation ◽  
Simple Approach ◽  
Foil Thickness ◽  
X Rays ◽  
X Ray ◽  
Hole Spectrum ◽  
Illumination System ◽  
Thin Foils ◽  
Intensity Ratios

Cliff and Lorimer (1) have proposed a simple approach to thin foil x-ray analy sis based on the ratio of x-ray peak intensities. However, there are several experimental pitfalls which must be recognized in obtaining the desired x-ray intensities. Undesirable x-ray induced fluorescence of the specimen can result from various mechanisms and leads to x-ray intensities not characteristic of electron excitation and further results in incorrect intensity ratios.In measuring the x-ray intensity ratio for NiAl as a function of foil thickness, Zaluzec and Fraser (2) found the ratio was not constant for thicknesses where absorption could be neglected. They demonstrated that this effect originated from x-ray induced fluorescence by blocking the beam with lead foil. The primary x-rays arise in the illumination system and result in varying intensity ratios and a finite x-ray spectrum even when the specimen is not intercepting the electron beam, an ‘in-hole’ spectrum. We have developed a second technique for detecting x-ray induced fluorescence based on the magnitude of the ‘in-hole’ spectrum with different filament emission currents and condenser apertures.

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