A spiral-shaped defected ground structure for coplanar waveguide

The authors present a spiral-shaped defected ground structure for coplanar waveguides (DGSCPW), which can be used as a kind of periodic structure for a planar transmission line. The proposed spiral-DGSCPW adopts spiral-shaped defects on both ground planes of CPW. Due to the spiral-shaped defects, the equivalent shunt inductance and slow-wave effects increase more rapidly than the standard CPW or CPW lines combined with the conventional PBG. The modeling and analysis to extract the equivalent circuit, increased slow-wave factor, and simulated and measured performances are presented.     

Silicon fabricated submicrometer stepper motor for microsurgicalprocedures

A linear stepper motor has been constructed with submicrometer step size and centimeter travel range. Silicon wafers with conventional dielectrics provide a basic electrostatic clamping mechanism, while a piezoelectric material serves as an electrical-to-mechanical power transducer. Movement is generated by using the inertial properties of an attached mass coupled with fast and slow expansions and contractions of the piezoelectric material. The fast transitions use the inertia of the mass to move the clamp, while the slow transitions move the mass while keeping the clamp fixed. Five prototype hand-held stepper motors have been successfully built and tested. The components of the motor fit within a pen-sized cylindrical stainless steel shell (15 cm × 1.2 cm) and deliver a displacement of 38 mm. For the given operating conditions, the tested handpieces had 1.2 mm/s advancement speeds against a 3 N load. The electrostatic clamp generates an attraction force of about 2 N using a clamp with an area of 3.75 cm² and 150 V across the faces. Maximum step sizes for the piezoelectric transducer (PZT) used here are slightly less than 10 μm, and steps less than 100 nm can be obtained with sufficiently low PZT voltages. Motor speed can be controlled by adjusting the operating frequency     

Moral education in the primary grades: An evaluation of a developmental curriculum.

Evaluated the effects of a semistructured group discussion approach to moral education on the level of usage of the concept of moral intentionality. Ss were 68 2nd graders, half from middle and half from lower socioeconomic status school districts. The medium of sound filmstrips to present moral dilemmas was employed during which teachers encouraged discussion and debate among Ss. Results indicate that Ss in the experimental condition showed higher level usage of the concept of moral intentionality on post- and follow-up testing than did a control group. However, due to the small number of classrooms involved in the study, results could not be definitively attributed to program effects rather than to teacher effects, and conclusions must be interpreted within the context of a pilot evaluation research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Environmentally assisted fatigue crack propagation in steel

The influence of various gasenous environments on fatigue crack propagation has been determined for three quenched and tempered steels with yield strength levels of 800 to 1400 MN/m². The crack growth rate was increased by an order of magnitude in low pressure (13 KPa) hydrogen, and by a factor of two in most mildly aggressive environments relative to the growth rate in vacuum. The gases oxygen, acetylene, carbon monoxide, and nitrous oxide were dominant in a combined environment with hydrogen while methane and carbon dioxide had only a small effect on crack propagation when added to hydrogen. The crack propagation in acetylene was intermediate between that in hydrogen and the mildly aggressive environments. The increase in fatigue crack propagation rate in the hydrogen environment was dependent on the temperature and the cyclic stress intensity. The fracture mode was transgranular for all conditions except the hydrogen influenced HP-9-4-20 fractures. These results are discussed relative to various stages of the hydrogen embrittlement mechanisms. In pacticular, the results are discussed with respect to the adsorption-dissociation of the environment, transport of the gaseous specie within the plasticly deformed zone by mobile dislocations and interaction with segregated impurities within the metal. H. L. MARCUS, formerly with Science center, Rockwell International, Thousand Oaks, CA     

LerM – Lehrsystem für Kontrapunkt-Kompositionen im Stile Palestrinas

Der Palestrina-Kontrapunkt nimmt in der Musiktheorie-Ausbildung eine wichtige Stellung ein.