Some computational tools for the analysis of through cracks in stiffened fuselage shells

Reliable analytical methods that predict the structural integrity and residual strength of aircraft fuselage structures containing cracks are needed to help to understand the behavior of pressurized stiffened shells with damage, so that it becomes possible to determine the safe life of such a shell. Of special importance is the ability to determine under what conditions local failure, once initiated, will propagate. In this paper we shall present a reliable and efficient method for computing the energy release rate for cracks of varying length in a typical stiffened metallic fuselage under general loading conditions. The models used in the simulation are derived from an extensive analysis of a fuselage barrel section subjected to operational flight loads. Energy release rates are computed as a function of the length of the crack, its location, and the crack propagation mode.     

Zeolite coated interdigital capacitors as a new type of gas sensor

The adsorption of a gas influences the dielectric constant of zeolites. This property is used as the sensitive component of a gas sensor.

Planar interdigital capacitors were coated with thin films of zeolites. When gas molecules are adsorbed, the dielectric constant of the zeolite is altered, which causes a change in the capacitance of the interdigital capacitor. This change is strongly dependent on the concentration of adsorbate in the gas phase.     

Toward a unified theory of similarity and recognition.

A new theory of similarity, rooted in the detection and recognition literatures, is developed. The general recognition theory assumes that the perceptual effect of a stimulus is random but that on any single trial it can be represented as a point in a multidimensional space. Similarity is a function of the overlap of perceptual distributions. It is shown that the general recognition theory contains Euclidean distance models of similarity as a special case but that unlike them, it is not constrained by any distance axioms. Three experiments are reported that test the empirical validity of the theory. In these experiments the general recognition theory accounts for similarity data as well as the currently popular similarity theories do, and it accounts for identification data as well as the longstanding "champion" identification model does. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adequacy of medical referrals to hospital emergency service

OBJECTIVE: To assess the correctness and diagnostic concordance in referrals of patients to hospital Casualty Departments (CD); and the possible differences between rural and urban health centres (HC) as well as between general practitioners (GP) and family and community medicine (FCM) specialists. DESIGN: Observational study of a crossover nature. SETTING: Health area 1 in the province of Badajoz. PATIENTS AND OTHER PARTICIPANTS: 800 patients, referred to their local hospital Casualty Department. MEASUREMENTS AND MAIN RESULTS: 50.5% of all referrals were considered justified. 15.1% of the patients referred were admitted to hospital. 50.7% of referrals from GPs were found to be correct, against 47% from FCM specialists; and 49% of those referred from rural HCs were correct, as against 45.9% of those referred from urban HCs (no significant differences). Only 54% of referrals had a diagnostic hypothesis, with diagnostic concordance at 50%. There was diagnostic concordance in 28.1% of GP referrals, against 33.3% of FCM specialists; and in 27.5% of those from rural HCs against 26.1% from urban HCs (no significant differences). CONCLUSIONS: We found no differences in the correctness of referrals or diagnostic concordance of patients seen in the CD of our city's health area, neither between patients referred from rural and urban HCs, nor between patients referred by GPs and FCM specialists.     

Direct-flow two-bath steelmaking furnace with high-powdered gas-oxygen roof burners

Orsk-Khalilovo Metallurgical Combine. Scientific-Research Institute of Metallurgy. Translated from Metallurg, No. 3, pp. 43–45, March, 1988.     

Characterization of the ntrBC genes of Azospirillum brasilense Sp7: their involvement in the regulation of nitrogenase synthesis and activity

The in vitro effect of citric acid application on periodontally involved root surfaces was investigated using scanning electron microscopy. Teeth were selected following specific criteria. The specimens were prepared for observation, and the features of the root surface were studied. The results demonstrated that a 3-minute application of citric acid (pH = 1.0) to the root surface after scaling and root planing demineralized the outer root surface, opened the dentinal tubules, and exposed collagen fibers. Scaling and root planing alone left the surface with a smear layer, scattered islands of cementum, and no collagen fibers or exposed dentinal tubules.     

Determination of the thermal conductivity of amorphous metallic alloys

Two techniques are suggested for identifying the temperature dependence of the thermal conductivity of a new class of materials. The results have been obtained for the metallic glass Co₇₇Fe₄Cr₇Si₈B₄.Institute for the Problems of Mechanical Engineering, Kharkov. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 3, pp. 314–320, September, 1992.     

A new family of continuous/discontinuous three-dimensional boundary elements with application to acoustic wave propagation

This paper presents a new family of continuous/discontinuous three-dimensional boundary elements which has been implemented in a computer system for acoustic wave propagation in the frequency domain. The system includes elements of different geometrical shapes, 'order of interpolation and degree of continuity. Results of several tests are included to show the efficiency of the family of elements.     

Determination of the relationship of pressure to process time in pneumatic forming of a round membrane in the superplastic condition

The deformation of a round membrane into a cylindrical matrix is considered. The relationship of pressure to time of the process of pneumatic forming in the superplastic condition is established. The results obtained are compared with known data. A conclusion is drawn on the applicability of the proposed approach for calculation of the production parameters of forming of axisymmetric parts in the superplastic condition.Translated from Problemy Prochnosti, No. 11, pp. 71–75, November, 1993.