Thermal stress intensity factors for a cracked cylinder under transient thermal loading

Transient thermal stress intensity factors are calculated at the deepest and the surface points of an internal axial semi-elliptical surface crack in a thick-walled cylinder under thermal shock. The method of calculation is based on the weight function and an effective procedure of integrating of the weight integrals. Time-dependent thermal boundary conditions are assumed to act on the inner surface of the pressurized cylinder. Exact analytical solutions are derived for the weight function, and then integrated to compute transient thermal stress intensity factors. In the special case of a steady state problem and also the pressurized cylinder, the results show to be in accordance with those cited in the literature.     

Bovine pancreatic lipase.I.Isolation, homogeneity, and characterization.

Bovine pancreatic lipase was isolated in pure form by lyophilization of fresh bovine pancreas, extraction of the enzyme with sucrose solution, fractional precipitation with ammonium sulfate and acetone, followed by chromatography on Sephadex G-100. The specific activity of the purest lipase fraction was 1750 micromoles fatty acid, liberated in 30 min per milligram of protein, indicating a purification of approximately 473-fold, with an overall yield of about 42%. Homogeneity of the enzyme was confirmed by rechromatography on Sephadex G-100 as well as with the gel electrophoretic and ultracentrifugal techniques. The purified enzyme gave a typical protein ultraviolet absorption spectrum with maximum absorption at 276 nm and minimum at 252 nm. The purified enzyme exhibited a single pH optimum of 8.8 and an isoelectric point near pH 5.5. Its optimum temperature was 37 C, and its optimum substrate concentration was 10%. These properties resembled those of milk lipase.     

Analysis of wear in deep-drawing process of a cylindrical cup

In the present investigation, a deep-drawing process forming a cylindrical cup is simulated using the finite element method to study the wear depth on the draw die arc segment. Both the Blank and the die are assumed to be deformable. For the blank, both the elasto-plastic and elasto-viscoplastic material behaviors are considered, while the die material is assumed to be elastic. The materials are isotropic and Von-Mises yield criterion is employed. Considering the elasto-viscoplastic behavior for the blank, the effect of punch speed on the wear depth of the die shoulder is investigated. Meanwhile, the effects of different process parameters such as the blank holder force, the die radius as well as the clearance between the punch and the die on the wear depth profile of the arc segment of the die are investigated and several conclusive results are presented. The results show to be in good agreement with those cited in literature.     

Fractal capacitors

A linear capacitor structure using fractal geometries is described. This capacitor exploits both lateral and vertical electric fields to increase the capacitance per unit area. Compared to standard parallel-plate capacitors, the parasitic bottom-plate capacitance is reduced. Unlike conventional metal-to-metal capacitors, the capacitance density increases with technology scaling. A classic fractal structure is implemented with 0.6-μm metal spacing, and a factor of 2.3 increase in the capacitance per unit area is observed. It is shown that capacitance boost factors in excess of ten may be possible as technology continues to scale. A computer-aided-design tool to automatically generate and analyze custom fractal layouts has been developed     

An 11 GHz 3-V SiGe voltage controlled oscillator with integratedresonator

A 10.5- to 11-GHz fully monolithic voltage controlled oscillator circuit implemented in a standard SiGe bipolar technology is presented. An oscillator phase noise of -78 to -87 dBc/Hz is achieved at 100-kHz offset. The tuning range is close to 5% with an on-chip varactor-tuned resonator and for a control voltage of 0 to 3 V. The circuit draws less than 8 mA from a 3-V supply including the reference branch bias current     

Adsorption of nickel by lignite

Process feasibility studies have been initiated to determine the possibilities of extracting metallic nickel by the lignite-adsorption route. Lignite proved to be a very effective adsorbent. Observations relating the adsorption of nickel by lignite to process variables are reported in this paper.     

Long backfire antenna with insular image guide feed for dual frequency operation

A long backfire antenna using an insular image waveguide feed compatible with microwave dielectric integrated circuit technology is presented. The antenna operates as a backfire component from 9.7 to 9.9 GHz and as an endfire antenna from 8.9 to 9.9 GHz, with symmetrical radiation patterns and low crosspolarisation. The important parameters of the antenna are experimentally optimised to give a maximum gain of 20 dB and 17 dB when working as a backfire and endfire antenna, respectively. This type of antenna can find extensive applications at millimetre-wave frequencies.