Models for the elastic deformation of honeycombs

A theoretical model has been developed for predicting the elastic constants of honeycombs based on the deformation of the honeycomb cells by flexure, stretching and hinging. This is an extension of earlier work based on flexure alone. The model has been used to derive expressions for the tensile moduli, shear moduli and Poisson's ratios. Examples are given of structures with a negative Poisson's ratio. It is shown how the properties can be tailored by varying the relative magnitudes of the force constants for the different deformation mechanisms. Off-axis elastic constants are also calculated and it is shown how the moduli and Poisson's ratios vary with applied loading direction. Depending on the geometry of the honeycomb the properties may be isotropie (for regular hexagons) or extremely anisotropic. Again, the degree of anisotropy is also affected by the relative magnitude of the force constants for the three deformation mechanisms.     

Extending typestate checking using conditional liveness analysis

The authors present a practical extension to typestate checking, which is capable of proving programs free of uninitialized variable errors even when these programs contain conditionally initialized variables where the initialization of a variable depends upon the equality of one or more tag variables to a constant. The user need not predeclare the relationship between a conditionally initialized variable and its tags, and this relationship may change from one point in the program to another. The technique generalizes liveness analysis to conditional liveness analysis. Like typestate checking, this technique incorporates a dataflow analysis algorithm in which each point in a program is labeled with a lattice point describing statically tracked information, including the initialization of variables. The labeling is then used to check for programming errors such as referencing a variable which may be uninitialized     

Continuous stimulated emission at T=293 K from separate-confinement heterostructure diode lasers with one layer of InAs quantum dots grown on vicinal GaAs(bd001) surfaces misoriented in the [010] direction in the active region

The electroluminescence and stimulated emission of lasers with one layer of InAs quantum dots (QD’s) grown in a single molecular-beam epitaxial process on vicinal GaAs(001) surfaces misoriented in the direction [010] by 2, 4 and 6° are investigated. It is discovered that an increase in the misorientation angle leads to a blue shift and a decrease in the full width at half maximum (FWHM) of the electroluminescence spectrum. This effect is attributed to a decrease in the size of the quantum dots and improvement in their size uniformity. A strong dependence of the threshold current density on the width of the spontaneous luminescence spectrum is discovered. The room-temperature threshold current density of the lasers with one layer of quantum dots and the spontaneous luminescence spectrum having the smallest FWHM (54 meV) equals 210 A/cm². Fiz. Tekh. Poluprovodn. 32, 1482–1486 (December 1998)     

On solving constrained optimization problems with neural networks:a penalty method approach

Deals with the use of neural networks to solve linear and nonlinear programming problems. The dynamics of these networks are analyzed. In particular, the dynamics of the canonical nonlinear programming circuit are analyzed. The circuit is shown to be a gradient system that seeks to minimize an unconstrained energy function that can be viewed as a penalty method approximation of the original problem. Next, the implementations that correspond to the dynamical canonical nonlinear programming circuit are examined. It is shown that the energy function that the system seeks to minimize is different than that of the canonical circuit, due to the saturation limits of op-amps in the circuit. It is also noted that this difference can cause the circuit to converge to a different state than the dynamical canonical circuit. To remedy this problem, a new circuit implementation is proposed.     

Psychiatric medication: what the occupational health nurse should know

1. Occupational health nurses need a general knowledge of psychiatric medications to work effectively with clients and their off site health providers. 2. Acquiring an understanding of the major classes of medications--anti-psychotic, anti-anxiety, anti-depressant, and antimanic--is important. 3. It is helpful to understand under what conditions and with which conditions psychotropic medications are helpful.     

Use of gas plasmas to increase breakdown strengths in polycarbonatefilm/foil capacitors

It is shown that the electrical breakdown voltages of polycarbonate film/metal foil capacitors can be increased. This can be achieved by briefly exposing the metal foil in these spirally wound film foil sections to a low-pressure, low-temperature gas plasma. Exposure of tin/lead foil to a 96% CF₄/4% O₂ gas plasma for four min, for example, produced >500% increase in breakdown voltage of sealed polycarbonate capacitors     

Sensors for the food industry

This article presents an overview of the results of a five-year research project on sensors for the food industry in Japan. This project was a government-sponsered research programme involving the food industry and the instrumentation industry, coordinated by the Japanese Ministry of Agriculture, Forestry and Fisheries. The programme focussed on 17 food processing operations and quality control tasks, where the need for an on-line (or rapid at-line) measurement had been established. The instrument development work employed biosensors pH and gas sensors, optical-imaging devices, as well as near-infrared, microwave, ultrasound and mechanical resonance techniques, together with robotics and advanced data-processing techniques.