Effect of crack-growth mechanism on the prediction of fracture load of adhesive joints

This paper presents observations regarding the cracking behavior of tensile-loaded structural adhesive joints. Experiments showed that fracture occurred by the development and propagation of a damage zone, rather than a single, sharp crack, and that the presence of the adhesive spew fillet did not affect the fracture load of the adhesive joints studied. For joints bonded with the mineral-filled epoxy Cybond 4523GB (American Cyanamid), there was approximately 5 mm of subcritical crack propagation prior to final fracture. Fracture-load predictions based on the initial uncracked geometry made in previous papers were unaffected by this small change in geometry. For joints bonded with the rubber-toughened epoxy Permabond ESP 310, approximately 50 mm of subcritical crack propagation was observed. It was again found that predictions made in previous papers on the basis of the initial geometry gave a good estimate of the final fracture load even though this subcritical crack propagation significantly altered the geometry, and thus the applied energy release rates. The effect of shear deformations of the adherends was also investigated, and it was found that shear deformations could be neglected in engineering calculations for joints subject to remote tensile loading.     

Unity of measurements and its maintenance. Fundamental concepts

We consider the group of fundamental concepts involved in the unity of measurements and its maintenance.Translated from Izmeritel'naya Tekhnika, No. 10, pp. 15–17, October, 1994.     

A multi-purpose CMOS sensor interface for low-power applications

A dedicated low-power CMOS transponder microchip is presented as part of a novel telemetry implant for biomedical applications. This mixed analog-digital circuit contains an identification code and collects information on physiological parameters, i.e., body temperature and physical activity, and on the status of the battery. To minimize the amount of data to be transmitted, a dedicated signal processing algorithm is embedded within its circuitry. All telemetry functions (encoding, modulation, generation of the carrier) are implemented on the integrated circuit. Emphasis is on a high degree of flexibility towards sensor inputs and internal data management, extreme miniaturization, and low-power consumption to allow a long implantation lifetime     

Optimum degeneration for minimum mismatch in bipolar currentsources

Statistical analysis of mismatch in bipolar degenerated current sources reveals the existence of an optimum degeneration for minimum mismatch. Extra degeneration does not improve matching but degrades it and forces unnecessary DC restrictions on the circuit     

Achievement of pencil-beam radiation from a TM01 modecircular waveguide source

A method employing appropriately placed parallel-metallic plates in the aperture of a TM₀₁ mode circular waveguide source so as to have it produce pencil-beam radiation is described and analyzed. Programmed computations, with experimental verification, are given for the case of a C-Band TM₀₁ source flared out to a conical horn so as to produce moderate (22 dBi) gain. Means of extending the method to achieve higher gains (40 dBi to 60 dBi) and to modify the plate arrangement so as to produce the same effect with a TE₀₁ mode are briefly outlined     

Combined statistical study of joint angles and ground reactionforces using component and multiple correspondence analysis

The purpose of this research is to propose a general methodology to draw gait patterns when including hip, knee and ankle angle excursions in the sagital plane and the three components of the ground reaction force. The multidimensional signal analysis procedure is divided into three main stages: 1) describing the six signals of each step through sliding averages computed for successive time windows, 2) analyzing separately the six step-by-window tables obtained for each signal through principal component analysis to reduce the excessive quantity of data, and 3) analyzing the most informative time windows of the six signals at the same time. To emphasize both linear and nonlinear relationships between the respective time windows, the signal range within a window is cut into fuzzy modalities such as, “low” “medium” and “large.” The resulting table is investigated using multiple correspondence analysis. The outcomes are gait patterns combining both time and space aspects. The factor planes obtained from multiple correspondence analysis constitute initial data models so that new data obtained from pathological gait can be directly projected onto them. Such an operation can be used to show how the rehabilitation of a particular subject evolves in relation to normal gait patterns     

Modeling pentode-like characteristics of recessed-gate staticinduction transistor

A new analytical model is described for the pentode-like region of the characteristics of recessed-gate SIT structures. The model allows one to investigate the transition from saturating characteristics of long channel JFET's to nonsaturating behavior of SIT devices, taking into account realistic device geometry     

Overgrown silicon PBT's: calculations and measurements

The device parameters of overgrown silicon permeable base transistors (PBT's) have been systematically investigated by two dimensional drift diffusion simulations and analytical calculations. Hence some design rules arise for optimizing the high frequency performance of PBT's. The calculations indicate the source-drain distance as the essential PBT parameter, which should be kept below 200 nm in order to expect unity-current-gain frequencies f_T over 50 GHZ. In addition, PBT's with buried monocrystalline CoSi₂-gates have been fabricated by high dose cobalt ion implantation through a grid-like mask into MOS-compatible n-type Si(100). Measurements revealed a transconductance of 70 mS/mm and a f _T value of 6 GHz. The comparison between measured and simulated output characteristics shows good agreement