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Graphene has excellent mechanical properties and vibration frequency is an important mechanical property. In this paper, the effects of doping elements and doping concentrations on the vibration characteristics of graphene nanoribbons were investigated by molecular dynamics simulation. The vibration characteristics are influenced by the doping element, depending on the bond structural difference in bond structure between doping atoms and carbon atoms. The vibration frequencies of Nitrogen (N)-doped and Nitrogen–Nitrogen (N–N)-doped graphene nanoribbons are slightly lower than those of pure graphene nanoribbons. However, the vibration frequencies of Sulfur (S)/Phosphorus (P)-doped and Sulfur–Sulfur (S–S)/Phosphorus–Phosphorus (P–P)-doped graphene nanoribbons are significantly lower than those of pure graphene nanoribbons. In addition, with the increase of S (P) doping concentration, the vibration frequency of monolayer graphene nanoribbons decreases gradually. [ABSTRACT FROM AUTHOR]

Anisotropy parabolic potential (APP) effects on ground state (GS) energy E 0 and the vibration frequency (VF) λ of weak-coupled magnetopolaron (MP) in asymmetric Gaussian quantum wells (AGQWs) were investigated using the linear combination operator and unitary transformation method. The obtained results showed that E 0 and λ were increased by increasing the barrier height V 0 of AGQWs as well as transverse and longitudinal confined strengths ω x and ω y of APP and decreased with increase in the asymmetric Gaussian confinement potential (AGCP) range R and transverse and longitudinal effective confined lengths l x and l y of APP. Thus, the GS energy and VF of MP could be changed by adjusting the confinement parameters of the APP and AGCP. The study of quantum wells' semiconductor materials has broad potential applications in semiconductor lasers, optoelectronic devices and quantum information. [ABSTRACT FROM AUTHOR]

This work investigates the influence of tool surface area (TSA) on the average surface roughness ( R a) , tool wear rate (TWR) and material removal rate (MRR) in the micro-electrical discharge machining (μ EDM). The effects of three different TSAs were investigated at three different discharge energy settings. It was observed that the TSA had substantial influence on μ EDM performance owing to scaling effect. Therefore, the low-frequency workpiece vibration was applied to improve the μ EDM performance. The surface topography of machined surfaces was examined using scanning electron microscopy to disclose the effect of TSA as well as vibration frequency on μ EDMed surfaces. [ABSTRACT FROM AUTHOR]

We studied the vibration frequencies of small double-clamped silicon nanobeams using a molecular dynamics method. The effects of cross-section area, size, and oxide layer were investigated through simulation. The results show that the vibration frequency decreases with increasing length, whereas it increases slightly with increasing cross-section area of the nanobeam. The existence and thickness of an oxide layer lead to increasing of the vibration frequency of silicon nanobeams. [ABSTRACT FROM AUTHOR]

In this study, vibratory stimuli with various intensities (four levels) and frequencies (10, 50, 100, 150, 200, 225, 250 and 300 Hz) were applied to the right index finger to extract cognitive characteristic functions for the intensity and frequency. For subjective assessment, an experiment was conducted with 30 healthy adults in their twenties who were right-handed and had normal cognitive function. One trial of the experiment was composed of a vibration phase (0.1 s) and a rest phase (10 s). After vibration simulation was applied once for each intensity and frequency, the participants filled out a subjective assessment form. After extracting the score of each word, the cognitive characteristic function was derived through discriminant analysis and regression analysis according to the frequency and intensity. Through the cognitive characteristic function, the level of cognitive characteristics of each word can be investigated according to the influence of the frequency and intensity. The results observed through the cognitive characteristics function of each word showed that the words affected by the frequency and intensity were "light," "thick," "heavy," "blunt," "vibrating," "fast" and "weak." "Itchy" and "slow" were cognitive characteristics affected only by the frequency, and "strong" and "push" were affected only by the intensity. Through the vibratory stimulation presentation parameters, i.e., frequency and intensity, the results capable of predicting the degrees of various cognitive characteristics were presented. [ABSTRACT FROM AUTHOR]

On the basis of Lee–Low–Pines (LLP) unitary transformation, the influence of external magnetic field, Rashba spin–orbit coupling and quantum size effect on the ground-state interaction energy of strong-coupling magnetopolarons in quantum disks (QDs) is studied by using the Tokuda improved linear combine operator method. The results show that the ground-state interaction energy of magnetopolarons consists of four parts: the energy caused by the confinement potential of QDs, interaction energy between the electron and external magnetic field, electron and longitudinal-optical (LO) phonon interaction energy and additional term of Rashba effect originating from phonons. The electron–LO phonon interaction energy Ee-ph and additional term of Rashba effect are always negative; the absolute value |Ee-ph| increases with increasing transverse confinement strength ω0, cyclotron frequency of external magnetic field ωc and electron–LO phonon coupling strength α, but decreases with increasing the thickness of QDs L; the state properties of magnetopolarons are closely linked with the sign of the ground-state interaction energy of magnetopolarons Eint and change of Eint with ωc, ω0, α and L. In addition, the vibration frequency of magnetopolarons λ increases with increasing ωc, ω0 and α, but decreases with increasing L. For the ground state of magnetopolarons in QDs, the electron–LO phonon interaction plays a significant role, meanwhile, the influence of Rashba spin–orbit coupling effect cannot be ignored. [ABSTRACT FROM AUTHOR]

Influence of the lattice vibration on the properties of the magnetopolaron in the parabolic quantum dots (QDs) is studied by using the Huybrechts' linear combination operator and Lee-Low-Pines (LLP) transformation methods. The expressions for the vibration frequency and the ground-state energy of the magnetopolaron as functions of the confinement strength of the QDs, the magnetic field and temperature are derived under the strong and weak coupling, respectively. The results of the numerical calculations show that the changes of the vibration frequency and ground-state energy of the magnetopolaron with the confinement strength of the QDs, the magnetic field and temperature are different under different couplings. The vibration frequency and the ground-state energy of the weak-coupling magnetopolaron and the vibration frequency of the strong-coupling magnetopolaron will increase with increase of the confinement strength of the QDs and cyclotron frequency, the vibration frequency and ground-state energy of the strong-coupling magnetopolaron. However, the ground-state energy of the weak-coupling magnetopolaron will decrease with increase of the temperature. The dependence of the ground-state energy of the strong-coupling magnetopolaron on the confinement strength of the QDs and cyclotron frequency is strongly influenced by the temperature. The remarkable influence of the temperature on the ground-state energy of the magnetopolaron arises when the temperature is relatively higher. [ABSTRACT FROM AUTHOR]