Novel Electrical Joints Using Deformation Machining Technology—Part II: Experimental Verification
This is the second part of the paper related to the exploration of deformation machining technology (DMT), originally developed at Bauman Moscow State Technical University, as it may apply to making electrical joints and comparing their performance to bolted and welded electrical joints. The DMT process is used to generate tooth-like profiles on two opposing surfaces that make the electrical joints which are later joined by applying a mechanical load. Part I contained a more detailed explanation of the DMT process and the description of the results of computer modeling of DMT joints in copper and aluminum. This paper provides the experimental results of the mechanical and electrical performance of copper and aluminum DMT joints which were compared to bolted and welded electrical joints of identical geometries. Measurements of tensile strength and electrical resistance, after thermal cycling and short-circuit testing, show equivalent or better performance of copper DMT joints compared with copper bolted and welded joints. In addition, it is observed that copper DMT joints have superior performance when compared with aluminum DMT joints, this was attributed to lesser gap filling and the springback effect that occurs after the mechanical load for making the joint is removed. The computer modeling results reported in Part I of this paper support these observations.
Novel Method of Single-Pass Threading by Cutter
The technological aspects and some results of a new method intended for producing threads and projections of the triangular profile on plastic metals are considered. The method is implemented according to the schemes of traditional machining with a simple tool such as a cutter. The method is intermediate between the threading based on the cutting process with a removal of the workpiece material and the threading based on metal cold flow with a redistribution of the workpiece material and combines both methods. The new principle and high value of the tool rake angle improve metal flow conditions. This leads to a significant reduction in the amount of material removed in the form of chips, reducing the required depth of cut, high surface quality of the thread, possibility of using smaller diametrical dimensions of the workpiece and possibility of using thin-walled tubes for threading. The authors theoretically justified and experimentally confirmed the selection of a manufacturing parameter to obtain a threaded profile of the required geometry.
An operational method for estimating signal to noise ratios from data acquired with imaging spectrometers
A method, using the concept of local means and local standard deviations of small imaging blocks and using a box counting procedure, has been developed for unsupervised estimation of the average signal to noise ratios of images in which the noise is additive. The method has been applied to simulated images with Gaussian noise, to images acquired with the Airborne Visible Infrared Imaging Spectrometer and with the Geophysical and Environmental Research Imaging Spectrometer. The method is compared with other techniques for estimating signal to noise ratios from imaging data. It is believed that the method is generally applicable to images having many small homogeneous blocks. Because the method does not take into account interband effects, it is not appropriate to use the method to estimate signal to noise ratios from images having nonnegligible interband radiometric calibration errors at spatial scales less than or equal to the size of the small imaging blocks used in the noise estimation.