A Special Topics Course in Perturbation Methods

A special topics course dealing with perturbation methods in applied mathematics which was recently taught at Stevens Institute of Technology is described. Since the course enrolment was comprised of undergraduate and graduate mathematics students as well as graduate students in engineering, an unusual course philosophy had to be developed and implemented. The approach taken to achieve this in both teaching techniques and selection of subject matter is discussed in detail. Finally, conclusions are drawn from the students’ and the instructor's experiences with the course which hopefully will be of value to those considering offering special topics courses in the future.     

A combined study of surface roughness in polycrystalline aluminium during uniaxial deformation using laser-induced photoemission and confocal microscopy

A new technique integrating measurements obtained by photo-stimulated electron (PSE) emission and scanning laser confocal microscopy (SLCM) has been developed to characterize the deformation of commercially pure aluminium in uniaxial plastic strain. Real time, in situ PSE signals provide details about the evolution and propagation rates of surface events during the deformation process. High-resolution SLCM measurements yield details describing the relative magnitude and spatial distribution of the surface features. During homogeneous deformation, uniform generation of surface area produces a monotonic increase in PSE intensity whereas necking induces a saturation condition. Analysis of the surface area created by the deformation revealed that the rate of generation correlates well with the PSE intensity. The consistencies in the data acquired with these two techniques signify that they yield complementary information and that the combination provides essential details about the deformation process in a material with low hardness such as an aluminium alloy.     

Seasonal Minimum and Maximum Solar Ultraviolet Exposure Measurements of Classroom Teachers Residing in Tropical North Queensland,Australia

The risk of keratinocyte skin cancer, malignant melanoma and ultraviolet radiation (UVR)‐induced eye disease is disproportionately higher in Australia and New Zealand compared to equivalent northern hemisphere latitudes. While many teachers are aware of the importance of reinforcing sun safety messages to students, many may not be aware of the considerable personal exposure risk while performing outdoor duties in locations experiencing high to extreme ambient UVR year‐round. Personal erythemally effective exposure of classroom teachers in tropical Townsville (19.3°S) was measured to establish seasonal extremes in exposure behavior. Mean daily personal exposure was higher in winter (91.2 J m^‐2, 0.91 Standard Erythema Dose [SED]) than summer (63.3 J m^?2, 0.63 SED). The range of exposures represents personal exposures that approximate current national guidelines for Australian workers at the study latitude of approximately 1.2 SED (30 J m^?2 effective to the International Commission on Non‐Ionizing Radiation Protection). Similar proportions of teachers spent more than 1 h outdoors per day in winter (28.6%) and summer (23.6%) as part of their teaching duties with seasonal differences having little effect on the time of exposure. Personal exposures for teachers peaked during both seasons near school meal break times at 11:00 am and 1:00 pm, respectively.     

Statistical model for intermolecular adhesion in pi-conjugated polymers

We propose an interchain binding mechanism in pi-conjugated polymers based on the intermolecular tunneling of the delocalized electrons occurring at points where the polymers cross. This mechanism predicts specific bound structures of chains that depend on whether they are semiconducting or metallic. Semiconducting chains should form polyacenelike states exhibiting binding at every other site, while (doped) metallic chains can bind at each site. We also show that solitons colocalize with the intermolecular binding sites thereby strengthening the binding effect and investigate the conformational statistics of the resulting bimolecular aggregates.     

The Arason invariant and mod 2 algebraic cycles

Let be a field, over a smooth variety with function field and a quadratic vector bundle over . Assuming that the generic fibre of is in , we compute the image of its Arason invariant

in by the differential of the Bloch-Ogus spectral sequence. This gives an obstruction to being a global cohomology class.

     

Implementation of ab initio multiple spawning in the Molpro quantum chemistry package

The ab initio multiple spawning (AIMS) method has been developed to solve the electronic and nuclear Schrodinger equations simultaneously for application to photochemical reaction dynamics. We discuss some details of the implementation of AIMS in the Molpro program package. A few aspects of the implementation are highlighted, including a new multiple timescale integrator and a scheme for solving the coupled-perturbed multiconfiguration self-consistent field (CP-MCSCF) equations in the context of ab initio molecular dynamics. The implementation is very efficient and we demonstrate calculations on the photoisomerization of ethylene using more than 5000 trajectory basis functions. We have included the capability for hybrid quantum mechanics/molecular mechanics (QM/MM) simulations within AIMS, and we investigate the role of an argon solvent in the photoisomerization of ethylene. Somewhat surprisingly, the surrounding argon has little effect on the timescale of non-adiabatic quenching in ethylene.     

Designing a Uniaxial Tension/Compression Test for Springback Analysis in High-Strength Steel Sheets

We describe an innovative design for an in-plane measurement technique that subjects thin sheet metal specimens to bidirectional loading. The goal of this measurement is to provide the critical performance data necessary to validate complex predictions of the work hardening behavior during reversed uniaxial deformation. In this approach, all of the principal forces applied to the specimen are continually measured in real-time throughout the test. This includes the lateral forces that are required to prevent out of plane displacements in the specimen that promote buckling. This additional information will, in turn, improve the accuracy of the compensation for the friction generated between the anti-bucking guides and the specimen during compression. The results from an initial series of experiments not only demonstrate that our approach is feasible, but that it generates data with the accuracy necessary to quantify the directionally-dependent changes in the yield behavior that occur when the strain path is reversed (i.e., the Bauschinger Effect).     

Reconfigurable Logic Devices on a Single Dopant Atom—Operation up to a Full Adder by Using Electrical Spectroscopy

A silicon field‐effect transistor is operated as a logic circuit by electrically addressing the ground and excited electronic states of an embedded single dopant atom. Experimental results—complemented by analytical and computational calculations—are presented. First, we show how a complete set of binary logic gates can be realized on the same hardware. Then, we show that these gates can be operated in parallel on the very same dopant up to the logic level of a full adder. To use the device not as a switch but as a full logic circuit, we make essential use of the excited electronic states of the dopant and of the ability to shift their energy by gating. The experimental ability to use two channels to measure the current flowing through the device and the conductance (dI/dV) allows for a robust reading of the output of the logic operations.