Vocabulary to speak about touch: analysis of the discourse of electric guitar players

This work presents a multidisciplinary approach to vibrotactile perception, applying linguistic methods to musical acoustics. We are interested more particularly in the sense of touch as a part of the multisensory experience of playing a musical instrument. Six words and their inflections are chosen from the literature in musical acoustics dealing with vibrotactile perception: “comfort”, “dynamics”, “response”, “feeling”, “touch” and “vibration”. Their use by musicians in playing situation is analyzed. The data used in this article comes from transcripts of two previous studies, conducted in French with professional guitarists natively speaking French. The linguistic analysis of the corpus is based on different features which help to categorize the utterances according to each observed parameter, namely the relationship with the sense of touch, the object that is qualified by the words under study and the implication in discourse of the interviewee. The results permit to understand the use of the six categories of words in relationship with the sense of touch, and provide perspectives to use some of these words to focus the discourse on the sense of touch in future studies.

Feed direction dependent milling dynamics of an asymmetric flexible machining system

Asymmetric flexible machining system has been widely used in NC machining. In traditional milling dynamics model, the cutter feed direction is usually defined as parallel to its vibration DOF, while the nonparallel condition and its induced milling dynamics response are not deeply considered. This paper presents a general dynamics modeling method for asymmetric flexible machining systems. Firstly, to the best of the author's knowledge, a new dimension named feed direction is proposed, which is used to establish the generalized coupling relationship between the vibration displacement and the regenerative milling force, thus improve the applicability of the milling dynamics model and reduce the experimental workload compared with the traditional modeling. Secondly, through the theoretical and experimental research, it is shown that the asymmetric flexible machining system has a significant feed direction dependent characteristics, and implied the existence of high performance machining region with higher stability and low SLE by contrast with the symmetrical milling system and the traditional model. Finally, by controlling the feed direction angle, the milling parameters in roughing and finishing operation are optimized, and the machining efficiency has been greatly improved on the premise of stable cutting and machining accuracy at last.

Structure and Dynamics of Curcumin Encapsulated Lecithin Micelles: A Molecular Dynamics Simulation Study

Curcumin is a natural product with potential pharmaceutical applications that can be augmented by drug delivery technology such as nano emulsion. Our study focuses on microscopic structural and dynamics response of curcumin encapsulation in micellar system with lecithin as a natural surfactant under variations of composition and temperature using molecular dynamics (MD) simulations. The results highlight the self-assembly of lecithin micelle, with curcumin encapsulated inside, from initial random configurations in the absence of external field. The variation of composition shows that lecithin can aggregate into spherical and rod-like micelle with the second critical micelle concentration lies between 0.17-0.22 mol dm−3. The radial local density centering at the micelle center of mass shows that the effective radius of micelle is indeed defined by the hydrophilic groups of lecithin molecule and theencapsulated curcumin molecules are positioned closer to these hydrophilic groups than the innermost part of the micelle. The spherical micelle is shown to be thermally stable within the temperature range of 277-310 K without a perceivable change in the spherical eccentricity. The dynamics of micelle are enhanced by the temperature, but it is shown to be insensitive to the variation of lecithin-curcumin composition within the studied range. Simulation results are in agreement with the pattern obtained from experimental results based on particle size, polydispersity index, and encapsulation efficiency.

Resonant modal interactions in micro/nano-mechanical structures

This paper considers nonlinear interactions between vibration modes with a focus on recent studies relevant to micro- and nanoscale mechanical resonators. Due to their inherently small damping and high susceptibility to nonlinearity, these devices have brought to light new phenomena and offer the potential for novel applications. Nonlinear interactions between vibration modes are well known to have the potential for generating a “zoo” of complicated bifurcation patterns and a wide variety of dynamic behaviors, including chaos. Here, we focus on more regular, robust, and predictable aspects of their dynamics, since these are most relevant to applications. The investigation is based on relatively simple two-mode models that are able to capture and predict a wide range of transient and sustained dynamical behaviors. The paper emphasizes modeling and analysis that has been done in support of recent experimental investigations and describes in full detail the analysis and attendant insights obtained from the models that are briefly described in the experimental papers. Standard analytical tools are employed, but the questions posed and the conclusions drawn are novel, as motivated by observations from experiments. The paper considers transient dynamics, response to harmonic forcing, and self-excited systems and describes phenomena such as extended coherence time during transient decay, zero dispersion response, and nonlinear frequency veering. The paper closes with some suggested directions for future studies in this area.

DYNAMICS RESPONSE OF THE HUMAN HEAD DURING DRYWALL IMPACT

Little experimental data has been reported on the biomechanics of head collisions with drywall sections. The dynamics of head collisions with rigid structures are well documented. However, impacts with compliant, composite structures are more difficult to analyze. The study objective was to correlate the severity of a head impact with damage to the drywall. A human head analog was instrumented with a tri-axial accelerometer and a uniaxial load cell was placed along the cervical spine axis. A randomized block design of drop height and head orientation was utilized. The test results indicated a primarily linear correlation between drop height and peak head acceleration, as well as correlation between drop height and the geometry of the indentation to the drywall. Head posture had little influence on wall damage, however, head extension resulted in a stiffer head-spine complex compared to a flexed posture. A two-factor ANOVA determined a statistically significant correlation between damage severity and impact velocity. The results obtained can be used by accident reconstructionists to approximate the impact severity of a head impacting drywall. The study data are limited to drywall sections of known, similar geometry, and does not apply to scenarios with a support beam directly beneath the drywall. Further studies are needed to investigate additional head postures.

Investigating the Influence of Fluid-Structure Interactions on Nonlinear System Identification

A complex fluid-structure interaction can often create nonlinear dynamic behaviour in the structure. This can be better estimated using nonlinear modal analysis, capable of identifying and quantifying the nonlinearity in the structure. In this study, the case of a vibrating beam submerged in liquid using a nonlinear parameter identification method is presented. This system is considered as an alternative propulsion mechanism, hence understanding the interaction between the fluid and the structure is necessary for its control. Here, impulse signals are used to characterise the numerical and experimental dynamics response of the system. Since the transient responses contain of a multi-component vibratory signals, a vibration decomposition method is used to separate the time response signals based on the dominant amplitude in the frequency response function. The separated time-series signals are then fitted to the nonlinear identification method to construct the backbone and damping curves. The modal parameters obtained from experimental data are then used as a base for the development of the analytical models. The analytical approaches are based on the Euler-Bernoulli beam theory with additional mass and quadratic damping functions to account for the presence of the fluid. Validations are carried out by comparing the dynamic responses of the analytical and experimental measurements demonstrating the accuracy of the model and hence, its suitability for control purposes.

Onion (Allium cepa L.) Yield and Growth Dynamics Response to In-Season Patterns of Nitrogen and Sulfur Uptake

The in-season trend of onion biomass and its yield depend on the dynamics of nitrogen (N) and sulfur (S) uptake. This hypothesis was verified based on a three-year (2009, 2010, 2011) field study (Poznan University of Life Sciences). The experimental factors consisted of N: 0, 60, 120 and S: 0, 30, 60 kg ha−1. The dynamics of onion total dry weight (TDW), total N uptake (TNU), and total S uptake (TSU) were determined at 10-day intervals. The in-season course of TDW and TNU was best described by the expolinear and TSU by the quadratic growth model. Sulfur uptake increased in onion at day after emergence (DAE) 40, independent of its rate with respect to SN control, resulting in increased N by 50%, and consequently higher yield. The maximum absolute S uptake rate (SCm), a factor defining yield, increased progressively with the N rate, but only in the absence of S application. Plants fertilized simultaneously with S and N showed a more complicated impact on SCm. The N rate of 120 kg ha−1 resulted in SCm reduction, leading to a yield drop. The expolinear model indicated an onion growth disturbance, revealed under unfavorable growth conditions, leading to yield depression.