Explosive Welding of Aluminum, Titanium and Zirconium to Copper Sheet Metal

The main material properties affecting the explosive weldability of a certain metal combination are the yield strength, the ductility, the density and the sonic velocity of the two metals. Successful welding of the metal combination depends mainly on the correct choice of the explosive welding parameters; i.e., the stand off distance, the weight of the explosive charge relative to the weight of the flyer plate and the detonation velocity of the explosive. Based on the measured and the handbook values of the properties of interest, the explosive welding parameters were calculated and the arrangements for the explosive welding of the Al alloy 6061-T6, titanium and zirconium to OFHC copper were determined. The relatively small sheet metal thickness (1/8") and the fact that the thickness of the explosive layer must exceed a certain minimum value were considered during the determination of the explosive welding conditions. The results of the metallographic investigations and the measurements of the shear strength at the interface demonstrate the usefulness of these calculations to minimize the number of experimental trials

Stability analysis of rotating beams rubbing on an elastic circular structure

This paper presents the stability analysis of a system composed of rotating beams on a flexible, circular fixed ring, using the Routh-Hurwitz criterion. The model displayed has been fully developed within the rotating frame by use of an energy approach. The beams considered possess two degrees of freedom (dofs), a flexural motion as well as a traction/compression motion. In-plane deformations of the ring will be considered. Divergences and mode couplings have thus been underscored within the rotating frame and in order to simplify understanding of all these phenomena, the dofs of the beams will first be treated separately and then together. The dynamics of radial rotating loads on an elastic ring can create divergence instabilities as well as post-critical mode couplings. Moreover, the flexural motion of beam rubbing on the ring can also lead to mode couplings and to the locus-veering phenomenon. The presence of rubbing seems to make the system unstable as soon as the rotational speed of the beams is greater than zero. Lastly, the influence of an angle between the beams and the normal to the ring's inner surface will be studied with respect to system stability, thus highlighting a shift frequency phenomenon

Community based rehabilitation by paraplegic - a case report

A journey of a young man started from day one in the hospital. When he came with the traumatic paraplegia, no doubt a paraplegic has to face a lot of challenges in his life when he came to know that his both legs are not working. He became bedridden and his moral is also become down for his future planning. But we accept the challenge, a team work by an orthopaedician and a physio-occupational therapist make it little easier. Postoperatively we prefer to offer rehabilitation through community base programme. Inspiration of hospital environment and equipment are going to help him for such kind of programme he accepts the challenge, basic aim of providing this programme is to reduce duration as well as incurred monitor losses. Special attraction of this case report is homemade bicycle, which served the purpose of providing repetitive rhythmic mobilisation of bilateral lower limbs which facilitates normal pattern of ambulation. Now he is ambulatory and goes back to his work. So, a person with spinal cord injury involved with their community with a little modification in his activity and equipment is worth for him. Traumatic paraplegia offers a big challenge to physio- occupational therapist due to long term recovery it takes.  For Such patients on regular follow up till complete recovery, we preferred community based rehabilitation. This made him independent and incurred reduced monitory losses

What causes the irregular cycle of the atmospheric tape recorder signal in HCN?

Variations in the mixing ratio of long-lived trace gases entering the stratosphere in the tropics are carried upward with the rising air with the signal being observable throughout the tropical lower stratosphere. This phenomenon, referred to as "atmospheric tape recorder" has previously been observed for water vapor, CO2, and CO which exhibit an annual cycle. Recently, based on Microwave Limb Sounder (MLS) and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) satellite measurements, the tape recorder signal has been observed for hydrogen cyanide (HCN) but with an approximately two-year period. Here we report on a model simulation of the HCN tape recorder for the time period 2002-2008 using the Chemical Lagrangian Model of the Stratosphere (CLaMS). The model can reproduce the observed pattern of the HCN tape recorder signal if time-resolved emissions from fires in Indonesia are used as lower boundary condition. This finding indicates that inter-annual variations in biomass burning in Indonesia, which are strongly influenced by El Nino events, control the HCN tape recorder signal. A longer time series of tropical HCN data will probably exhibit an irregular cycle rather than a regular biannual cycle. Citation: Pommrich, R., R. Muller, J.-U. Grooss, G. Gunther, P. Konopka, M. Riese, A. Heil, M. Schultz, H.-C. Pumphrey, and K. A. Walker (2010), What causes the irregular cycle of the atmospheric tape recorder signal in HCN?, Geophys. Res. Lett., 37, L16805, doi:10.1029/2010GL044056