3-D acoustic analysis of elliptical chamber mufflers having an end-inlet and a side-outlet: An impedance matrix approach

The acoustical behavior of an elliptical chamber muffler having an end-inlet and side-outlet port is analyzed semi-analytically. A uniform piston source is assumed to model the 3-D acoustic field in the elliptical chamber cavity. Towards this end, we consider the modal expansion of acoustic pressure field in the elliptical cavity in terms of angular and radial Mathieu functions, subjected to rigid wall condition, whereupon under the assumption of a point source, Green's function is obtained. On integrating this function over piston area of the side or end port and dividing it by piston area, one obtains the acoustic field, whence one can find the impedance matrix parameters characterizing the 2-port system. The acoustic performance of these configurations is evaluated in terms of transmission loss (TL). The analytical results thus obtained are compared with 3-D HA carried on a commercial software for certain muffler configurations. These show excellent agreement, thereby validating the 3-D semi-analytical piston driven model. The influence of the chamber length as well as the angular and axial location of the end and side ports on TL performance is also discussed, thus providing useful guidelines to the muffler designer. (c) 2011 Elsevier B.V. All rights reserved.

Time-Dependent Predominance of Nonhomologous DNA End-Joining Pathways during Embryonic Development in Mice

Repair of DNA double-strand breaks (DSBs) is crucial for maintaining genomic integrity during the successful development of a fertilized egg into a whole organism. To date, the mechanism of DSB repair in postimplantation embryos has been largely unknown. In the present study, using a cell-free repair system derived from the different embryonic stages of mice, we find that canonical nonhomologous end joining (NHEJ), one of the major DSB repair pathways in mammals, is predominant at 14.5 day of embryonic development. Interestingly, all four types of DSBs tested were repaired by ligase IV/XRCC4 and Ku-dependent classical NHEJ. Characterization of end-joined junctions and expression studies further showed evidences for canonical NHEJ. Strikingly, in contrast to the above, we observed noncanonical end joining accompanied by DSB resection, dependent on microhomology and ligase III in 18.5-day embryos. Interestingly, we observed an elevated expression of CtIP, MRE11, and NBS1 at this stage, suggesting that it could act as a switch between classical end joining and microhomology-mediated end joining at later stages of embryonic development. Thus, our results establish for the first time the existence of both canonical and alternative NHEJ pathways during the postimplantation stages of mammalian embryonic development. (C) 2012 Elsevier Ltd. All rights reserved.

Sesbania Mosaic Virus (SeMV) Infectious Clone: Possible Mechanism of 3 ` and 5 ` End Repair and Role of Polyprotein Processing in Viral Replication

Sesbania mosaic virus (SeMV) is a positive stranded RNA virus belonging to the genus Sobemovirus. Construction of an infectious clone is an essential step for deciphering the virus gene functions in vivo. Using Agrobacterium based transient expression system we show that SeMV icDNA is infectious on Sesbania grandiflora and Cyamopsis tetragonoloba plants. The efficiency of icDNA infection was found to be significantly high on Cyamopsis plants when compared to that on Sesbania grandiflora. The coat protein could be detected within 6 days post infiltration in the infiltrated leaves. Different species of viral RNA (double stranded and single stranded genomic and subgenomic RNA) could be detected upon northern analysis, suggesting that complete replication had taken place. Based on the analysis of the sequences at the genomic termini of progeny RNA from SeMV icDNA infiltrated leaves and those of its 3' and 5' terminal deletion mutants, we propose a possible mechanism for 3' and 5' end repair in vivo. Mutation of the cleavage sites in the polyproteins encoded by ORF 2 resulted in complete loss of infection by the icDNA, suggesting the importance of correct polyprotein processing at all the four cleavage sites for viral replication. Complementation analysis suggested that ORF 2 gene products can act in trans. However, the trans acting ability of ORF 2 gene products was abolished upon deletion of the N-terminal hydrophobic domain of polyprotein 2a and 2ab, suggesting that these products necessarily function at the replication site, where they are anchored to membranes.

A Numerical Scheme for Three-Dimensional Front Propagation and Control of Jordan Mode

As an example of a front propagation, we study the propagation of a three-dimensional nonlinear wavefront into a polytropic gas in a uniform state and at rest. The successive positions and geometry of the wavefront are obtained by solving the conservation form of equations of a weakly nonlinear ray theory. The proposed set of equations forms a weakly hyperbolic system of seven conservation laws with an additional vector constraint, each of whose components is a divergence-free condition. This constraint is an involution for the system of conservation laws, and it is termed a geometric solenoidal constraint. The analysis of a Cauchy problem for the linearized system shows that when this constraint is satisfied initially, the solution does not exhibit any Jordan mode. For the numerical simulation of the conservation laws we employ a high resolution central scheme. The second order accuracy of the scheme is achieved by using MUSCL-type reconstructions and Runge-Kutta time discretizations. A constrained transport-type technique is used to enforce the geometric solenoidal constraint. The results of several numerical experiments are presented, which confirm the efficiency and robustness of the proposed numerical method and the control of the Jordan mode.

Vehicle Detection Tool - VDtect

The report talks about the implementation of Vehicle Detection tool using opensource software - WxPython. The main functionality of this tool includes collection of data, plotting of magnetometer data and the count of the vehicles detected. The report list about how installation process and various functionality of the tool.

Dynamics of end-to-end loop formation: A flexible chain in the presence of hydrodynamic interaction

Based on the Wilemski-Fixman approach G. Wilemski, M. Fixman, J. Chem. Phys. 60 (1974) 866], we show that, for a flexible chain in theta solvent, hydrodynamic interaction treated with a pre-averaging approximation makes ring closing faster if the chain is not very short. We also show that the ring closing time for a long chain with hydrodynamic interaction in theta solvent scales with the chain length (N) as N-1.5, in agreement with the previous renormalization group calculation based prediction by Freidman and O'Shaughnessy B. Friedman, B. O'Shaughnessy, Phys. Rev. A 40 (1989) 5950]. (C) 2012 Elsevier B.V. All rights reserved.

On the Role of Higher-Order Evanescent Modes in End-Offset Inlet and End-Centered Outlet Elliptical Flow-Reversal Chamber Mufflers

This paper deals with the role of the higher-order evanescent modes generated at the area discontinuities in the acoustic attenuation characteristics of an elliptical end-chamber muffler with an end-offset inlet and end-centered outlet. It has been observed that with an increase in length, the muffler undergoes a transition from being acoustically short to acoustically long. Short end chambers and long end chambers are characterized by transverse plane waves and axial plane waves, respectively, in the low-frequency range. The nondimensional frequency limit k(0)(D-1/2) or k(0)R(0) as well as the chamber length to inlet/outlet pipe diameter ratio, i.e., L/d(0), up to which the muffler behaves like a short chamber and the corresponding limit beyond which the muffler is acoustically long are determined. The limits between which neither the transverse plane-wave model nor the conventional axial plane-wave model gives a satisfactory prediction have also been determined, the region being called the intermediate range. The end-correction expression for this muffler configuration in the acoustically long limit has been obtained using 3-D FEA carried on commercial software, covering most of the dimension range used in the design exercise. Development of a method of combining the transverse plane wave model with the axial plane wave model using the impedance Z] matrix is another noteworthy contribution of this work.

A Compliant End-Effector to Passively Limit the Force in Tele-Operated Tissue-Cutting

This paper presents a compliant end-effector that cuts soft tissues and senses the cutting forces. The end-effector is designed to have an upper threshold on cutting forces to facilitate safe handling of tissue during automated cutting. This is demonstrated with nonlinear finite element analysis and experimental results obtained by cutting inhomogeneous phantom tissue. The cutting forces are estimated using a vision-based technique that uses amplified elastic deformation of the compliant end-effector. We also demonstrate an immersive tele-operated tissue-cutting system together with a haptic device that gives real-time force feedback to the user. DOI: 10.1115/1.4007638]