Identification of sloshing noises using convolutional neural network.

Sloshing in fuel tanks has become a new source of noise in hybrid and high-end vehicles in the wake of reduced noise from major sources like the engine. It occurs due to the interactions of fluid inside the tank under various driving conditions of the vehicle. Interactions of fluid with the tank walls cause hit noise, and the fluid-fluid interactions cause splash noise. As the generation mechanism is different, the hit and splash noises demand different noise controlling strategies. Thus, identifying these noises during the design stage is important for implementing effective solutions in designing a quieter fuel tank. This paper presents a convolutional neural network (CNN) based methodology for the identification of sloshing noises under different conditions of fill level, excitation, baffle configuration, etc. Data for training and testing the network are collected using a reciprocating test setup, which facilitates the generation of hit and splash noises in a rectangular tank. The identification accuracy of the features learned by CNN is compared with the hand-crafted features using support vector machines. The applicability of the proposed CNN model is tested for practical scenarios like vehicle braking, where different types of sloshing noises occur in quick succession.

Green's function approach for the transmission loss of concentrically multi-layered circular dissipative chamber.

An analytical method has been proposed by using Green's function analysis to find the transmission loss (TL) of a concentrically multi-layered circular dissipative chamber. Each layer of the chamber is filled with a porous acoustic absorptive material and is separated from the adjacent one by a thin perforated screen. A tailored Green's function for this configuration, in the absence of mean flow, is expressed as the summation of eigenfunctions of the central duct. In the analysis, the walls of the chamber are assumed to be acoustically rigid. The cumulative effect of the layers has been incorporated in terms of the reflection coefficient in the eigenfunctions of the central duct. By using the piston analogy approach at the inlet and outlet ports of the chamber, the total velocity potential generated inside the central duct is estimated. Thence, the transfer matrix is evaluated to predict the TL. The results obtained from the current method are in good agreement with the numerical models and available literature. A parametric study has been conducted to investigate the effect of the number of layers, and their arrangement with respect to thickness and flow resistivity, on the acoustic performance of the chamber.

Transmission loss characteristics of an annular cavity with arbitrary port locations using Green's function method.

The prediction of transmission loss characteristics of a short chamber requires the study of both longitudinal as well as transverse modes. This prompts the development of a three-dimensional (3D) transfer matrix, which can address the wave propagation in all three directions. Accordingly, an analytical methodology for transmission loss characteristics of an annular cavity using Green's function method is presented in this paper. The 3D wave equation is used to derive the mode shape functions for the cavity. The average pressure on the inlet and outlet ports is predicted using the Green's function derived from the mode shapes. Three different port location configurations of the annular cavity are considered for establishing the analytical methodology, viz., face-inlet-face-outlet (FIFO), side-inlet-side-outlet (SISO), and face-inlet-side-outlet (FISO). Numerical model results are used to corroborate the analytical results. The effects of geometrical parameters on the transmission loss are studied.

Structure-activity relationship studies of novel pyrazole and imidazole carboxamides as cannabinoid-1 (CB1) antagonists.

The synthesis and biological evaluation of novel pyrazole and imidazole carboxamides as CB1 antagonists are described. As a part of eastern amide SAR, various chemically diverse motifs were introduced on rimonabant template. The central pyrazole core was also replaced with its conformationally constrained motif and imidazole moieties. In general, a range of modifications were well tolerated. Several molecules with low- and sub-nanomolar potencies were identified as potent CB1 receptor antagonists. The in vivo proof of principle for weight loss is demonstrated with a lead compound in DIO mice model.

Novel pyrazole-3-carboxamide derivatives as cannabinoid-1 (CB1) antagonists: journey from non-polar to polar amides.

The synthesis and biological evaluation of novel pyrazole-3-carboxamide derivatives as CB1 antagonists are described. As a part of eastern amide SAR, various chemically diverse motifs were introduced. In general, a range of modifications were well tolerated. Several molecules with high polar surface area were also identified as potent CB1 receptor antagonists. The in vivo proof of principle for weight loss is exemplified with a lead compound from this series.

Analytical prediction of break-out noise from a reactive rectangular plenum with four flexible walls.

This paper describes an analytical calculation of break-out noise from a rectangular plenum with four flexible walls by incorporating three-dimensional effects along with the acoustical and structural wave coupling phenomena. The breakout noise from rectangular plenums is important and the coupling between acoustic waves within the plenum and structural waves in the flexible plenum walls plays a critical role in prediction of the transverse transmission loss. The first step in breakout noise prediction is to calculate the inside plenum pressure field and the normal flexible plenum wall vibration by using an impedance-mobility approach, which results in a compact matrix formulation. In the impedance-mobility compact matrix (IMCM) approach, it is presumed that the coupled response can be described in terms of finite sets of the uncoupled acoustic subsystem and the structural subsystem. The flexible walls of the plenum are modeled as an unfolded plate to calculate natural frequencies and mode shapes of the uncoupled structural subsystem. The second step is to calculate the radiated sound power from the flexible walls using Kirchhoff-Helmholtz (KH) integral formulation. Analytical results are validated with finite element and boundary element (FEM-BEM) numerical models.

Discovery of novel, orally available benzimidazoles as melanin concentrating hormone receptor 1 (MCHR1) antagonists.

Melanin concentrating hormone (MCH) is an important mediator of energy homeostasis and plays role in several disorders such as obesity, stress, depression and anxiety. The synthesis and biological evaluation of novel benzimidazole derivatives as MCHR1 antagonists are described. The in vivo proof of principle for weight loss with a lead compound from this series is exemplified.

Analytical prediction of the breakout noise from a rectangular cavity with one compliant wall.

This paper describes an analytical calculation of breakout noise by incorporating three-dimensional effects along with the acoustical and structural wave coupling phenomena. The breakout noise phenomena from cavities are important at low frequencies, and the coupling between acoustic waves and structural waves plays a critical role in prediction of the transverse transmission loss. The first step in the breakout noise prediction is to calculate the inside cavity pressure field and the normal cavity wall vibration by using an impedance-mobility approach, which results in a compact matrix formulation. The second step is to calculate the radiated sound power from an unbaffled plate formulation that poses formidable challenges on computational time. The proposed formulation helps in reducing the computational time substantially by converting quadruple integrals into single integrals using an appropriate coordinate transformation technique. Analytical results are validated with the finite element/boundary element numerical models.