Whole body vibration in mountain-rescue operations

In mountain-rescue operations injured people are generally exposed to vibrations and shocks that can be potential causes of physical conditions worsening. Such vibrations can derive both from patient's body manipulations (e.g. when it is being loaded and immobilized on a stretcher) and from forces coming from the transport devices and vehicles. Despite the general feeling that during this kind of operations the levels of transmitted vibrations to the injured can be quite large and potentially dangerous, there is practically no study in literature providing reliable parameters (i.e. measurements) to support or dismiss these beliefs. This paper reports the results of a measurement campaign carried-out in order to outline, identify and quantify the excitations a human body is exposed to, during typical transportation phases related to mountain-rescue operations. The work mainly presents and discusses the experimental setup with the aim of focusing on the problems related to this kind of measurements; the results of the experimental campaign carried-out for the measurement of the vibrations undergone by a human body during a simulated rescue operation are presented and discussed as well. Such simulation includes three phases of transportation: on a hand-held stretcher, on an ambulance and on a helicopter. The work is not intended to supply a complete characterization and analysis of vibrations transmission during any rescue operation but just to provide a preliminary overview and to define a measurement method that can be applied for a more comprehensive characterization. With such aims measurements were carried out in on-field situations stated as “typical” by rescue experts and data then analyzed both with standard procedures and algorithms (e.g. ISO 2631s weighting curves) and with the commonly used statistical indexes; in the analysis it is important to be aware that standardized measurement procedures and indexes, created to verify comfort or health-risks of workers, might not fit the case of a generic patient who experienced a serious mountain accident. The work includes also a laboratory activity mainly related to mechanical characterization of the stretcher used in the field tests. The most interesting result of the study is the comparison of the vibration levels in the various rescue phases that, even when using different indicators, shows that the most critical issue is due to hand transportation despite the bad judgment usually expressed for helicopter flight.     

On the low vibration modes observed in a sphere submitted to a tangential contact force

In this paper we discuss the existence of translational and rotational displacements of a sphere submitted to a tangential contact force. On the basis of the Bogdanov and Skvortsov’s works [A.N. Bogdanov, A.T. Skvortsov, Sov. Phys. Acoust. 38 (1992) 224–226.] the dispersion equation has been established and solved for any value of the frequency in the case of the linear approximation. The present experimental analysis confirms that it exists two branches: an upper branch associated to the translation of the sphere and a lower branch characteristic of the rotation of the bead.     

Heat propagation due to torsional vibration of shafts

Torsional vibration of rotating shafts can yield substantial temperatures in the shaft due to heat generated from material damping. It has been recently observed that such a situation in electric generators can lead to insulation failures and machine outages. In the study reported here forced torsional vibration is assumed, and both lumped mass and continuous systems are considered. The hysteretic model for material damping is used to yield the heat generation in the elastic deformation range and an elastoplastic material is assumed in the plastic range. The heat conduction equation is solved for a cylindrical shaft with surface cooling. Closed form solutions and expressions for the maximum temperatures and the maximum surface temperatures are obtained and tabulated for design purposes. It is shown that substantial temperatures can develop in shafts undergoing torsional vibration.     

Even-harmonic generation due to beyond-Born-Oppenheimer dynamics

We calculate the harmonic spectrum generated by a model HD molecule in a strong laser pulse. The unequal nuclear masses lead to the emission of even harmonics, i.e., photon frequencies which are even multiples of the laser frequency. The effect does not occur within the Born-Oppenheimer approximation. In the high-frequency region, the even harmonics are almost of the same order of magnitude as the odd ones.     

Molecular vibration dynamics in molecule-surface interactions

A quantum mechanical coupled channels approach to associative or recombinative desorption and scattering of diatomic molecules is described. The formulation is based on the concept of a reaction path and allows prediction of the vibrational excitation of desorbing molecules. We first consider very light molecules such as H₂ and D₂ desorbing via a Langmuir-Hinshelwood reaction. In a simple model neglecting rotations and substrate vibrations, the dependence of molecular vibrational excitation on incident energy, the curvature of the reaction path and the position and height of the saddle point are discussed. Various experimental results can be described with reasonable parameters. Vibrational excitation in Eley-Rideal reactions and rotational excitations in general are discussed only in a semiquantitative way. For heavier molecules the coupling to substrate vibrations in principle will become more important. Arguments will be presented that for the problem of vibrational excitation in desorption and scattering this coupling may still be neglected approximately. Results for vibrational excitations of CuF desorbing from Cu are in support of this simple point of view.     

Cyclicity of laryngeal cavity resonance due to vocal fold vibration

Acoustic effects of the time-varying glottal area due to vocal fold vibration on the laryngeal cavity resonance were investigated based on vocal tract area functions and acoustic analysis. The laryngeal cavity consists of the vestibular and ventricular parts of the larynx, and gives rise to a regional acoustic resonance within the vocal tract, with this resonance imparting an extra formant to the vocal tract resonance pattern. Vocal tract transfer functions of the five Japanese vowels uttered by three male subjects were calculated under open- and closed-glottis conditions. The results revealed that the resonance appears at the frequency region from 3.0 to 3.7 kHz when the glottis is closed and disappears when it is open. Real spectra estimated from open- and closed-glottis periods of vowel sounds also showed the on-off pattern of the resonance within a pitch period. Furthermore, a time-domain acoustic analysis of vowels indicated that the resonance component could be observed as a pitch-synchronized rise-and-fall pattern of the bandpass amplitude. The cyclic nature of the resonance can be explained as the laryngeal cavity acting as a closed tube that generates the resonance during a closed-glottis period, but damps the resonance off during an open-glottis period.     

Quantum decoherence due to non-linear dynamics of environment

We discuss quantum decoherence in an open system which couples with a non-linear environment with finite degrees of freedom. Even if the degrees of freedom of the environment are finite, the strong non-linearity of the environment is expected to destroy quantum coherence of the open system like a heat bath with infinite degrees of freedom. In order to demonstrate this fact, we use two-dimensional kicked rotors as the environment and investigate a master equation for a reduced density matrix which is obtained by coarse-graining the environmental degrees of freedom. Our numerical simulation shows that when the non-linearity of the environment exceeds a critical strength, quantum coherence of the open system is irreversibly destroyed. This decoherence is due to the uncorrelated response of the environment to the open system and is related to the chaotic property of the non-linear environment.     

Ultrafast photo-induced turning of magnetization and its relaxation dynamics in GaMnAs

We report that,by linearly polarized pumping of different wavelengths,Kerr transients appear at zero magnetic field only in the case when GaMnAs samples are initialized at 3 K by first applying a 0.8 Tesla field and then returning to zero field.We find that,instead of magnetization precession,the near-band gap excitation induces a coherent out-of-plane turning of magnetization,which shows very long relaxation dynamics with no precession.When photon energy increases,the peak value of the Kerr transient incre...     

Annoyance due to railway vibration at different times of the day

The time of day when vibration occurs is considered as a factor influencing the human response to vibration. The aim of the present paper is to identify the times of day during which railway vibration causes the greatest annoyance, to measure the differences between annoyance responses for different time periods and to obtain estimates of the time of day penalties. This was achieved using data from case studies comprised of face-to-face interviews and internal vibration measurements (N=755). Results indicate that vibration annoyance differs with time of day and that separate time of day weights can be applied when considering exposure-response relationships from railway vibration in residential environments.     

Acceleration response spectrum for predicting floor vibration due to occupant walking

Annoying vibrations caused by occupant walking is an important serviceability problem for long-span floors. At the design stage the floor?s structural arrangement may frequently change to cater for the owner?s varying requirements. An efficient and accurate approach for predicting a floor?s acceleration response is thus of great significance. This paper presents a design-oriented acceleration response spectrum for calculating a floor?s response given the floor?s modal characteristics and a specified confidence level. 2204 measured footfall traces from 61 test subjects were used to generate 10 s peak root-mean-square acceleration response spectra, on which a piecewise mathematical representation is based. The proposed response spectrum consists of three main parts: the first harmonic plateau ranging from 1.5 to 2.5 Hz, the second harmonic plateau ranging from 3.0 to 5.0 Hz and the descending part going with frequencies from 5.0 to 10.0 Hz. The representative value of each plateau and the mathematical representation for the descending curve were determined statistically for different confidence levels. Furthermore, the effects of factors, such as floor span, occupant stride length, higher modes of vibration, boundary conditions and peak acceleration response, on the proposed spectrum have been investigated and a modification measure for each factor is suggested. A detailed application procedure for the proposed spectrum approach is presented and has been applied to four existing floors to predict their acceleration responses. Comparison between predicted and field measured responses shows that the measured accelerations of the four floors are generally close to or slightly higher than the predicted values for the 75 percent confidence level, but are all lower than the predicted values for the 95 percent confidence level. Therefore the suggested spectrum-based approach can be used for predicting a floor?s response subject to a single person walking.     

Control of exciton dynamics in nanodots for quantum operations

We present a theory to further a new perspective of proactive control of exciton dynamics in the quantum limit. Circularly polarized optical pulses in a semiconductor nanodot are used to control the dynamics of two interacting excitons of opposite polarizations. Shaping of femtosecond laser pulses keeps the quantum operation within the decoherence time. Computation of the fidelity of the operations and application to the complete solution of a minimal quantum computing algorithm demonstrate in theory the feasibility of quantum control.     

Simplified approach to the vibration analysis of elastic plates due to sonic boom

A theoretical study of the response of a flat plate to a sonic boom excitation is presented. For such a study, the problem of transient vibrations of elastic plates having clamped or simply supported boundary conditions under a pulse load in the shape of a capital N corresponding to a typical far-field sonic boom disturbance is discussed in a new fashion by using the concept of iso-amplitude contour lines on the surface of the plate. Series solutions consisting of products of eigenfunctions times functions of time are employed to analyse the motions. As an illustration of the technique, an elliptical plate subjected to a typical N wave arriving at normal incidence is chosen as a model because this involves a curvilinear boundary of a relatively simple shape, yet has no simple exact solution. Closed form solutions are obtained for both clamped as well as simply supported edges. The results have technical importance for the prediction of response of window panes and wall-panels to sonic boom. All details are explained by graphs.     

Entanglement dynamics in quantum operations using superconducting phase qubits

The decoherence of quantum states in superconducting phase qubits under the impact of quantum noise is considered. The creating, maintaining, and breaking of entanglement in quantum operations important in creating full-scale quantum computers based on superconducting elements are analyzed.     

Magnetization dynamics due to pure spin currents in magnetic double layers

The magnetization dynamics in magnetic double layers is affected by spin-pump and spin-sink effects. So far, only the spin pumping and its effect on the magnetic damping has been studied. However, due to conservation of angular momentum this spin current also leads to magnetic excitation of the layer dissipating this angular momentum. In this Letter we use time resolved magneto-optic Kerr effect to directly show the excitation due to the pure spin current. In particular, we observe magnetization dynamics due to transfer of angular momentum in magnetic double layers. In contrast to other experiments where a spin polarized charge current is passed through a nanomagnet, the effects discussed in this Letter are based on pure spin currents without net transfer of electric charge.     

Nonlinear dynamics of convection patterns in a binary mixture subjected to finite-frequency vibration

Nonlinear evolution of two-dimensional convection patterns is considered for an incompressible binary mixture with negative Soret coupling in a horizontal layer subjected to finite-frequency vertical vibration of arbitrary amplitude. A numerical analysis is performed under impermeability conditions on rigid boundaries, which can be implemented in a laboratory experiment. The dependence of flow intensity on vibration amplitude is examined for the first and second resonance regions in the parameter space of thermal vibrational convection. The numerical results agree with the stability boundaries of equilibrium states predicted by linear theory. A qualitative difference in the dynamics of nonlinear oscillation is exposed between the regions corresponding to critical perturbations at the subharmonic and fundamental frequencies. Regular and chaotic dynamics, as well as hysteretic transitions between the fundamental and subharmonic modes, are revealed.     

Relationship between low-frequency aircraft noise and annoyance due to rattle and vibration

A near-replication of a study of the annoyance of rattle and vibration attributable to aircraft noise [Fidell et al., J. Acoust. Soc. Am. 106, 1408-1415 (1999)] was conducted in the vicinity of Minneapolis-St. Paul International Airport (MSP). The findings of the current study were similar to those reported earlier with respect to the types of objects cited as sources of rattle in homes, frequencies of notice of rattle, and the prevalence of annoyance due to aircraft noise-induced rattle. A reliably lower prevalence rate of annoyance (but not of complaints) with rattle and vibration was noted among respondents living in homes that had been treated to achieve a 5-dB improvement in A-weighted noise reduction than among respondents living in untreated homes. This difference is not due to any substantive increase in low-frequency noise reduction of acoustically treated homes, but may be associated with installation of nonrattling windows. Common interpretations of the prevalence of a consequential degree of annoyance attributable to low-frequency aircraft noise may be developed from the combined results of the present and prior studies.     

Polaronic effects due to surface optical vibration modes in a freestanding cylindrical wurtzite nanowire

The ground-state polaron self-trapped energy and effective mass due to the surface optical (SO) phonon modes in a freestanding wurtzite GaN nanowire (NW) were studied by means of the Lee–Low–Pines variational approach. Based on the dielectric continuum and Loudon’s uniaxial crystal models, the polar optical phonon modes in the one-dimensional (1D) systems are analyzed, and the vibrating spectra of SO modes and electron–SO phonon coupling functions are discussed and analyzed. The calculations on the ground-state polaron self-trapped energy and correction of effective mass due to the SO phonon modes in the 1D GaN NWs reveal that the polaron self-trapped energy and correction of effective mass are far larger than those in 1D GaAs NW systems. The reasons resulting in this obvious difference in the two 1D structures are mainly due to the different electron–phonon coupling constants and electron effective masses of bulk materials constituting the two types of 1D confined system. Finally, the polaronic properties of the wurtzite 1D GaN NWs have been compared with those of the wurtzite GaN-based two-dimensional quantum wells. The physical origination of these characteristics and their distinction in the different-dimensionality systems has been analyzed in depth.