Electronic image formation in high-voltage TEM by sequential pixel acquisition

We describe a complete hybrid imaging system for the electronic detection and manipulation of high-voltage TEM images. The system includes a recently incorporated two-dimensional beam deflector for dissecting the image into pixels by displacing it in a raster in front of an aperture leading to an electron detector. The characteristics of images thus formed by sequential pixel acquisition and displayed on a CRT are discussed and illustrated. Absorption or thickness profiles are also obtained by displaying the scanned pixel intensity in Y-modulation. Similarly, the displacement of an entire diffraction pattern allows the intensities of individual diffraction spots to be quantitated directly over a wide dynamic range. The direct splitting of the image into electronically controlled pixels can be applied to local mass measurements and to energy-loss analysis by means of a simple magnetic prism that can also provide energy filtering in lieu of a more elaborate electron-optical, image-preserving system.     

Design considerations for tunnel diode non-linear transmission lines

A tunnel diode non-linear transmission line has been investigated for second and third harmonic generation purposes. Design criteria are given and performance predictions have been obtained simulating the single diode behavior by means of a polynomial expression. An optimization of the non-linear transmission line as a harmonic generator has been obtained as a function of the number of diodes, their separation distances and the bias voltage.     

Reliability of Daniels systems subject to Gaussian load processes

A general method is developed for estimating reliability of Daniels systems subject to quasistatic and dynamic Gaussian load processes. The method is based on a generalization of the Slepian model, an identity involving first passage time probabilities and conditional mean crossing rates of response processes, and first/second order reliability methods. The use of the method is illustrated by an example.     

Stabilizing model predictive control: On the enlargement of the terminal set

It is well known that a large terminal set leads to a large region where the model predictive control problem is feasible without the need for a long prediction horizon. This paper proposes a new method for the enlargement of the terminal set. Different from existing approaches, the method uses the convex hull of trajectories as the basis for the construction. These trajectories may be any feasible trajectories of the system terminating in an invariant set that contains the origin and are not restricted to consist of equilibrium points only. The resulting terminal controller is the solution of an optimization problem depending on the state and is therefore in general a nonlinear function. Copyright © 2014 John Wiley & Sons, Ltd.     

Spontaneous copolymerization of 2-methyl-2-oxazoline and N-phenyl maleimide

Summary The copolymerizations of 2-methyl-2-oxazoline and N-phenyl maleimide in bulk or in solution,at 60°C or room temperature are reported. The initiation is spontaneous and is due to the formation of zwitterion by interaction of the two monomers. The copolymers are statistical,more rich in maleimide units and propagation reaction can take place both by anions and zwitterions.     

Poly(methyl methacrylate)-block-polysulfide-block-poly(methyl methacrylate) copolymers obtained by free-radical polymerization combined with oxidative coupling

Summary Poly(methyl methacrylate)-block-polysulfide-block-poly(methyl methacrylate) copolymers were synthesized for the first time through a new method involving the free radical polymerization of MMA in the presence of a thiocol oligomer as a chain transfer agent, followed by chemical oxidation of the remaining SH end-groups. The chain transfer constant of the SH end-groups of the thiocol was estimated from the rate of consumption of the thiol groups versus the rate of consumption of the monomer (C_T=0.67). The triblock copolymers synthesized were characterized by SEC and ¹H NMR measurements.     

Reliability of degrading dynamic systems

Methods are developed for finding the reliability of Daniels systems and plates with cracks that are subjected to dynamic random load processes. Reliability of these systems is defined, respectively, as the probability that there is at least an unfailed fiber and crack length does not exceed a critical value during a reference period. Properties of conditional mean crossing rates and diffusion models are used in analysis.