A new global and direct integral formulation for 2D potential problems

2021 ◽  
Vol 125 ◽  
pp. 233-240
Author(s):  
Chao Zhang ◽  
Zhuojia Fu ◽  
Yaoming Zhang
Keyword(s):  
Integral Formulation ◽  
Direct Integral ◽  
Potential Problems

Muffler Performance Studies Using a Direct Mixed-Body Boundary Element Method and a Three-Point Method for Evaluating Transmission Loss

1996 ◽  
Vol 118 (3) ◽  
pp. 479-484 ◽  
Author(s):  
T. W. Wu ◽  
G. C. Wan
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Velocity Potential ◽  
Transmission Loss ◽  
Point Method ◽  
Integral Formulation ◽  
Pressure Jump ◽  
Direct Integral ◽  
Body Boundary ◽  
Element Method

In this paper, a single-domain boundary element method is presented for muffler analysis. This method is based on a direct mixed-body boundary integral formulation recently developed for acoustic radiation and scattering from a mix of regular and thin bodies. The main feature of the mixed-body integral formulation is that it can handle all kinds of complex internal geometries, such as thin baffles, extended inlet/outlet tubes, and perforated tubes, without using the tedious multi-domain approach. The variables used in the direct integral formulation are the velocity potential (or sound pressure) on the regular wall surfaces, and the velocity potential jump (or pressure jump) on any thin-body or perforated surfaces. The linear impedance boundary condition proposed by Sullivan and Crocker (1978) for perforated tubes is incorporated into the mixed-body integral formulation. The transmission loss is evaluated by a new method called “the three-point method.” Unlike the conventional four-pole transfer-matrix approach that requires two separate computer runs for each frequency, the three-point method can directly evaluate the transmission loss in one single boundary-element run. Numerical results are compared to existing experimental data for three different muffler configurations.

Microbulldozing and Microchiseling

1969 ◽  
Vol 27 ◽  
pp. 134-135
Author(s):  
J.N. Ramsey ◽  
D.P. Cameron ◽  
F.W. Schneider
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Material Handling ◽  
Microprobe Analysis ◽  
Foreign Matter ◽  
Specific Location ◽  
Potential Problems ◽  
Knoop Indenter ◽  
Scanning Electron ◽  
Microhardness Tester

As computer components become smaller the analytical methods used to examine them and the material handling techniques must become more sensitive, and more sophisticated. We have used microbulldozing and microchiseling in conjunction with scanning electron microscopy, replica electron microscopy, and microprobe analysis for studying actual and potential problems with developmental and pilot line devices. Foreign matter, corrosion, etc, in specific locations are mechanically loosened from their substrates and removed by “extraction replication,” and examined in the appropriate instrument. The mechanical loosening is done in a controlled manner by using a microhardness tester—we use the attachment designed for our Reichert metallograph. The working tool is a pyramid shaped diamond (a Knoop indenter) which can be pushed into the specimen with a controlled pressure and in a specific location.

The “Mixing” of Implant Systems

1991 ◽  
Vol 4 (02) ◽  
pp. 38-45 ◽  
Author(s):  
F. Baumgart
Keyword(s):  
Stainless Steel ◽  
Additional Risk ◽  
Bone Screw ◽  
Application Technique ◽  
Quality Controls ◽  
Implant Materials ◽  
Osteosynthesis Plate ◽  
Potential Problems ◽  
Manufacturing Procedure

SummaryThe so-called “mixing” of implants and instruments from different producers entertain certain risks.The use of standardized implant materials (e.g. stainless steel ISO 5832/1) from different producers is necessary but is not sufficient to justify the use of an osteosynthesis plate from one source and a bone screw from another.The design, dimensions, tolerances, manufacturing procedure, quality controls, and application technique of the instruments and implants also vary according to make. This can lead to damage, failure or fracture of the biomechanical system called “osteosynthesis” and hence the failure of the treatment undertaken. In the end, it is the patient who pays for these problems.Some examples also illustrate the potential problems for the staff and institutions involved.The use of a unique, consistent, well-tested, and approved set of implants and instruments is to be strongly recommended to avoid any additional risk.

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