ISOTHERMAL FATIGUE BEHAVIOR OF SIGMA/T1METAL 21S LAMINATES,PART I: EXPERIMENTAL RESULTS

Experimental results are reported on the effect of static and cyclic loading (at 0.1 and 0.001 Hz) on the inelastic response of and damage development in (0)4, (0190), and (0/ ±45/90), SiC/Ti (Sigma/Timetal 21S) laminates, and the Timetal 21S matrix, at 650^°C and 21^°C. At the elevated temperature, viscoplastic deformation of the matrix can be observed even at relatively low applied stresses. At both temperatures, reduction of unloading elastic moduli of the laminates, which indicates onset of damage by interface decohesion, also starts after hailing to relatively low stresses. The cyclic loading rate has a significant effect on the number of cycles to failure, but not on the endurance limit of the (0/90), and (0/ ±45/90), laminates loaded by constant-amplitude tension at 650^°C. In the (0)₄ laminate, higher endurance limits were detected at 0.1 Hz than at 0.001 Hz However, regardless of loading rate and layup, the total strain at failure under both static and cyclic loading at 650^°C was measured at 1 ±0.1%. The experimental results are interpreted by micromecha-nical models in Part II [1].     

Anticorrosive zinc decanoate additive in acrylate varnish

This work is focused on the inhibitory effect of zinc decanoate on steel substrates for improvement of acrylate varnish anticorrosion performance. Experiments were carried out on a bare steel surface in sodium sulphate solution as well as on samples painted with acrylate varnish. The efficiency of inhibition was estimated by electrochemical impedance spectroscopy and an exposure test in a condensation chamber. A cross-section of the modified varnish was observed by scanning electron microscopy. Decanoate mobility on the surface was estimated by energy-dispersive X-ray analysis and infrared spectroscopy. Zinc decanoate provides very good inhibiting efficiency, about 65%. The mobility of decanoate on the surface is limited and it can protect rather small defects. Zinc decanoate can be used as an environmentally friendly anticorrosive additive in varnishes for preservation practice.     

Computer Analysis of Spatial Integration in Vertebrate Retinal Horizontal Cells

A model is developed for the electrically coupled horizontal cells of the vertebrate retina. The model consists of a weighted distributed-parameter network in which the elements have direct cellular significance: transmembrane conductance and capacitance, and radial coupling resistance. Membrane polarization is viewed as a change in the overall membrane conductance in response to photoreceptor influence. Model simulation is implemented on a computer using a circuit analysis program. As a structural representation of the S-space, the model accurately spreads potential, but fails to integrate photoreceptor activity spatially like the S-space. It has been suggested that retinal scattering is the cause of this discrepancy, but the analysis here indicates that photoreceptor coupling is probably the major influence.     

Calibration and standardization of microwave ovens for fixation of brain and peripheral nerve tissue

BACKGROUND: The role of the inhibitory neurotransmitter gamma aminobutyric acid (GABA) in schizophrenia has previously been investigated using postmortem material. Recently, using single photon emission tomography (SPET) with the selective benzodiazepine antagonist 123I-Iomazenil as the radioligand, we have demonstrated an in vivo relationship between reduced GABAA/benzodiazepine receptor binding and the severity of positive symptomatology in schizophrenia. The present study aimed to build on this using the same in vivo scanning techniques, and relating findings to cognitive functioning. METHODS: Ten nonpsychiatric control subjects and 15 schizophrenic patients, matched for age and handedness, were scanned. A battery of neuropsychologic tests was also administered. RESULTS: Correlational analysis revealed a pattern of increased correlations between GABAA/benzodiazepine receptor binding and task performance, in the schizophrenic group compared to the control group. CONCLUSIONS: Findings are preliminary but suggest a relationship between reduced GABAA/benzodiazepine receptor binding and poorer cognitive functioning, involving memory and visual attention processes, in the schizophrenic group but not in the control group. A role for GABA in the pathophysiology of schizophrenia is suggested. Limitations of the present study and suggestions for future research are discussed.     

Conceptual entropy and its effect on class hierarchies

All systems that undergo frequent change characteristically tend toward disorder. This is known as entropy and is recognized in all branches of science. Class hierarchies are shared structures which, if useful, undergo frequent change in the form of additional subclassing, modification to existing classes, and sometimes the restructuring of the hierarchy itself. Given this frequent change, we can expect class hierarchies to exhibit entropic tendencies, which we term conceptual entropy. Conceptual entropy is manifested by increasing conceptual inconsistency as we travel down the hierarchy. That is, the deeper the level of the hierarchy, the greater the probability that a subclass will not consistently extend and/or specialize the concept of its superclass. Constructing and maintaining consistent class hierarchies is one of the most difficult activities of object-oriented design. The article describes an automated classification tool that helps minimize conceptual entropy     

Deriving a subjective testing methodology for digital circuitmultiplication and packetized voice systems

The CCITT expert group on speech quality, formed in part to derive methodologies for evaluating new speech technologies, is emphasizing the assessment of digital circuit multiplication and packetized voice systems. Study group XII was requested to assess the performance of digital circuit multiplication equipment (DCME). The authors discuss DCME terminology, applications, testing alternatives, and issues that need to be addressed     

Comdex之谜

在炫耀其获奖的最新型笔记本电脑和其它产品的同时,Toshiba也在展会上发表了最引人注目的声明