Holographic Visualization of Noise Emissions from a Small Ducted Fan

Cylindrical Nearfield Acoustical Holography (NAH) based on a multi-scan, cross-spectral measurement was used to visualize the sound field of a ducted fan, and the ability of this procedure to quantify source modification effects is illustrated here

Concept homo duplex et individualisme durkheimien

Prenant appui sur Les formes élémentaires de la vie religieuse, ce mémoire s'intéresse à la nature et au fonctionnement de l'âme humaine par le biais du concept homo duplex. Esquissé dans l'œuvre de 1912, le syntagme est utilisé dans le cadre d'articles parus en 1913 et 1914. Émile Durkheim y précise aussi le caractère essentiel de toute religion : la vertu dynamogénique. Mettant en scène les composantes collective et individuelle de l'âme, le dualisme durkheimien affirme l'existence de deux systèmes d'états de conscience et de leur interaction. Un premier chapitre a pour objectif de suivre Durkheim dans le cheminement intellectuel qui le conduit à l'utilisation du concept homo duplex. Le second chapitre, aussi fidèle à la production de l'auteur, cherche à donner toute son extension à la notion d'individualisme. Y sont distinguées les unes des autres quatre formes d'individualisme, dont une qui peut être considérée comme typiquement durkheimienne. L'objectif de la démarche est de démontrer que, dans les dernières années de sa vie et dans ses efforts pour élaborer une science des faits moraux, ce fondateur de la sociologie française aurait mis d'avant le concept homo duplex afin d'introduire ses contemporains à une ontologie suggérant une morale individuelle qui va au-delà de la pensée kantienne. Accordant une attention particulière à l'étude de la composante individuelle de l'âme et considérant qu'une confusion à la fois sémantique et conceptuelle peut subsister entre différents types d'individualismes, nous nous proposons de répondre à une question principale : qu'est-ce qui caractérise l'individualisme durkheimien? \ud ______________________________________________________________________________ \ud MOTS-CLÉS DE L’AUTEUR : Durkheim, individualisme, homo duplex, néocriticisme, morale

Noise Control And Speech Intelligibility Improvement Of A Toll Plaza

Vehicular toll roads are one component of many municipal transportation systems. Open communication windows, often used in tollbooths, facilitate essential communication and monetary transactions. However, the vehicle noise generated outside the booth is easily transmitted into the booth via the open window. Personnel working at toll collection plazas are exposed to extended, continuous traffic noise. Sustained noise levels of this nature may cause hearing loss, induce fatigue or stress, and reduce worker productivity. The annoyance and discomfort related to continuous noise exposure may create an unpleasant working condition and may affect the hospitality of the tollbooth operators and their attitude toward customers. Furthermore, the noise level may hinder communication with customers and may compromise safety. Reduction of the noise level and an improvement in speech intelligibility are highly desirable. The acoustics of a typical toll plaza and structural noise control strategies were modeled using a beam tracing technique. Noise control strategies involved the application sound absorbing material to the overhead canopy, the construction of sound absorbing partial barriers, and the treatment of tollbooth walls with sound absorbing material. In terms of noise control, the results suggest that the direct field is more important that the reflected field. The effects of active noise control (ANC) systems to reduce traffic noise and improve speech intelligibility at the toll plaza was investigated. The ANC systems included a range of headsets and a prototype external unit designed to create a local region of attenuation. Significant noise reduction can be achieved with a sealed, closed ear ANC headsets. However, the various systems seemed to have little positive effect upon speech intelligibility under traffic noise conditions. The result imply that the signal to noise ratio under toll plaza conditions is poor and that level overloading effects may further reduce intelligibility. Altered systems were modeled to improve the signal to noise ratio and reduce the noise level. The improved systems utilize a directional microphone and a sealed ANC headset. With a high order directional microphone, good speech intelligibility is achievable even in the presence of toll plaza vehicle noise

NCAD2008-73088 A METHOD FOR NOISE REDUCTION IN HYDRAULIC LINES

ABSTRACT Sound transmission in hydraulic lines is of great importance in many engineering applications. Sound produced from hydraulic pumps may be radiated to the environment, and transmitted between components through flexible hoses, often modelled as shell-type structures. Noise in hydraulic lines filled with flowing fluid is generated through complex fluid-structure interactions. In this project, a conceptual muffler configuration consisting of a set of alternating shell segments was investigated. By varying parameters such as material properties and the hose dimensions, both fluid and structural waves in the hose are attenuated through the creation of stop bands at the operating frequency. In this paper, thick-and thin-shell theories were investigated. It was found that, for low frequencies or long wavelengths, consistent results were obtained from both theories. The transfer matrix method was used in conjunction with Floquet theory in the analysis of the periodic shell system. Preliminary results showed that numerous stop bands appear and substantial attenuation can be achieved. The first two natural frequencies of a shell with and without fluid loading were computed. Their values agree with similar results from other researchers. Finally, several parameters were varied to study their effects on the natural frequencies. These results will be used later in the design of the shell attenuator

Range‐separated density functional theory using multiresolution analysis and quantum computing

Quantum computers are expected to outperform classical computers for specific problems in quantum chemistry. Such calculations remain expensive, but costs can be lowered through the partition of the molecular system. In the present study, partition was achieved with range-separated density functional theory (RS-DFT). The use of RS-DFT reduces both the basis set size and the active space size dependence of the ground state energy in comparison with the use of wave function theory (WFT) alone. The utilization of pair natural orbitals (PNOs) in place of canonical molecular orbitals (MOs) results in more compact qubit Hamiltonians. To test this strategy, a basis-set independent framework, known as multiresolution analysis (MRA), was employed to generate PNOs. Tests were conducted with the variational quantum eigensolver for a number of molecules. The results show that the proposed approach reduces the number of qubits needed to reach a target energy accuracy

Programming hydrogel adhesion with engineered polymer network topology

Hydrogel adhesion that can be easily modulated in magnitude, space, and time is desirable in many emerging applications ranging from tissue engineering, and soft robotics, to wearable devices. In synthetic materials, these complex adhesion behaviors are often achieved individually with mechanisms and apparatus that are difficult to integrate. Here, we report a universal strategy to embody multifaceted adhesion programmability in synthetic hydrogels. By designing the surface network topology of a hydrogel, supramolecular linkages that result in contrasting adhesion behaviors are formed on the hydrogel interface. The incorporation of different topological linkages leads to dynamically tunable adhesion with high-resolution spatial programmability without alteration of bulk mechanics and chemistry. Further, the association of linkages enables stable and tunable adhesion kinetics that can be tailored to suit different applications. We rationalize the physics of chain slippage, rupture, and diffusion that underpins emergent programmable behaviors. We then incorporate the strategy into the designs of various devices such as smart wound patches, fluidic channels, drug-eluting devices, and reconfigurable soft robotics. Our study presents a simple and robust platform in which adhesion controllability in multiple aspects can be easily integrated into a single design of a hydrogel network