Finite volume distance field solution applied to medial axis transform

Accurate and efficient computation of the nearest wall distance d (or level set) is important for many areas of computational science/engineering. Differential equation-based distance/ level set algorithms, such as the hyperbolic-natured Eikonal equation, have demonstrated valuable computational efficiency. Here, in the context, as an 'auxiliary' equation to the main flow equations, the Eikonal equation is solved efficiently with two different finite volume approaches (the cell vertex and cell-centered). Application of the distance solution is studied for various geometries. Moreover, a procedure using the differential field to obtain the medial axis transform (MAT) for different geometries is presented. The latter provides a skeleton representation of geometric models that has many useful analysis properties. As an alternative approach to the pure geometric methods (e.g. the Voronoi approach), the current d-MAT procedure bypasses many difficulties that are usually encountered by pure geometric methods, especially in three dimensional space. It is also shown that the d-MAT approach provides the potential to sculpt/control the MAT form for specialized solution purposes. Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc.

Linear and nonlinear intersubband optical properties in a step quantum well with an applied electric field

Within the framework of the effective-mass envelope-function theory, the field-dependent intersubband optical properties of a Al0.4Ga0.6As/Al0.2Ga0.8As/GaAs step quantum well are investigated theoretically based on the periodic boundary condition. A very large Stark shift occurs when the lowest subband electron remains confined to the small well while the higher subband electron confined to the big well. The optical nonlinearity in a step well due to resonant intersubband transition (ISBT) is analyzed using a density-matrix approach. The second-harmonic generation coefficient chi(2 omega)((2)) and nonlinear optical rectification chi(0)((2)) have also been investigated theoretically. The results show that the ISBT in a step well can generate very large second order optical nonlinearities, chi(0)((2)) and chi(2 omega)((2)) can be tuned by the electric field over a wide range.

Polarization switching current of vertical cavity surface-emitting Lasers in an applied electric field

The polarization of vertical-cavity surface-emitting laser (VCSEL) can be controlled by electro-optic birefringence. We calculated the birefringence resulted from external electric field which was imposed on the top DBR of VCSEL by assuming that the two polarization modes were in the same place of the gain spectra in the absence of electric field beginning. By modifying SFM, the affection of the electric field strength on the polarization switching currents between the two polarization modes had been shown.

Field-amplified sample stacking capillary electrophoresis with electrochemiluminescence applied to the determination of illicit drugs on banknotes

Capillary electrophoresis (CE) with Ru(bpy)(3)(2+) electrochemiluminescence. (ECL) detection system was established to the determination of contamination of banknotes with controlled drugs and a high efficiency on-column field-amplified sample stacking (FASS) technique was also optimized to increase the ECL intensity. The method was illustrated using heroin and cocaine, which are two typical and popular illicit drugs. Highest sample stacking was obtained when 0.01 mM acetic acid was chosen for sample dissolution with electrokinetical injection for 6 s at 17 kV. Under the optimized conditions: ECL detection at 1.2 V, separation voltage 10.0 kV, 20 mM phosphate-acetate (pH 7.2) as running buffer, 5 mM Ru(bpy)(3)(2+) with 50 mM phosphate-acetate (pH 7.2) in the detection cell, the standard curves were linear in the range of 7.50 x 10(-8) to 1.00 x 10(-5) M for heroin and 2.50 x 10(-7) to 1.00 x 10(-4) M for cocaine and detection limits of 50 nM for heroin and 60 nM for cocaine were achieved (S/N = 3), respectively. Relative standard derivations of the ECL intensity and the migration time were 3.50 and 0.51% for heroin and 4.44 and 0.12% for cocaine, respectively.The developed method was successfully applied to the determination of heroin and cocaine on illicit drug contaminated banknotes without any damage of the paper currency.

Examination of the "all hazards" approach to disaster management as applied to field disaster management and pre-hospital care in Australia

Disasters, emergencies, incidents, and major incidents - they all come back to the same thing regardless of what they are called. The common denominator is that there is loss of life, injury to people and animals and damage and destruction of property. The management of such events relies on four phases: 1. Prevention 2. Preparation 3. Response 4. Recovery Each of these phases is managed in a different way and often by different teams. Here, concentration has been given to phases 2 and 3, with particular emphasis on phase 3, Response. The words used to describe such events are often related to legislation. The terminology is detailed later. However, whatever the description, whenever prevention is not possible, or fails, then the need is to respond. Response is always better when the responders are prepared. Training is a major part of response preparation and this book is designed to assist those in the health industry who need to be ready when something happens. One of the training packages for responders is the Major Incident Medical Management and Support (MIMMS) Course and this work was designed to supplement the manual prepared by Hodgetts and Macway-Jones(87) in the UK. Included is what the health services responder, who may be sent to an event in which the main concern is trauma, should know. Concentration is on the initial response and does not deal in any detail with hospital reaction, the public health aspects, or the mental health support that provides psychological help to victims and responders, and which are also essential parts of disaster management. People, in times of disaster, have always been quick to offer assistance. It is now well recognised however, that the 'enthusiastic amateur', whilst being a well meaning volunteer, isn't always what is needed. All too often such people have made things worse and have sometimes ended up as victims themselves. There is a place now for volunteers and there probably always will be. The big difference is that these people must be well informed, well trained and well practiced if they are to be effective. Fortunately such people and organisations do exist. Without the work of the St John Ambulance, the State Emergency Service, the Rural Fire Service the Red Cross and the Volunteer Rescue Association, to mention only a few, our response to disasters would be far less effective. There is a strong history of individuals being available to help the community in times of crisis. Mostly these people were volunteers but there has also always been the need for a core of professional support. In the recent past, professional support mechanisms have been developed from lessons learned, particularly to situations that need a rapid and well organised response. As lessons are learned from an analysis of events, philosophy and methods have changed. Our present system is not perfect and perhaps never will be. The need for an 'all-hazards approach' makes detailed planning very difficult and so there will probably always be criticisms about the way an event was handled. Hindsight is a wonderful thing, provided we learn from it. That means that this text is certainly not the 'last word' and revisions as we learn from experience will be inevitable. Because the author works primarily in New South Wales, many of the explanations and examples are specific to that state. In Australia disaster response is a State, rather than a Commonwealth, responsibility and consequently, and inevitably, there are differences in management between the states and territories within Australia. With the influence of Emergency Management Australia, these differences are being reduced. This means that across state and territory boundaries, assistance is common and interstate teams can be deployed and assimilated into the response rapidly, safely, effectively and with minimum explanation. This text sets out to increase the understanding of what is required, what is in place and how the processes of response are managed. By way of introduction and background, examples are given of those situations that have occurred, or could happen. Man Made Disasters has been divided into two distinct sections. Those which are related to structures or transport and those related directly to people. The first section, Chapter 3, includes: • Transport accidents involving land, rail, sea or air vehicles. • Collapse of buildings for reasons other than earthquakes or storms. • Industrial accidents, including the release of hazardous substances and nuclear events. A second section dealing with the consequences of the direct actions of people is separated as Chapter 4, entitled 'People Disasters'. Included are: • Crowd incidents involving sports and entertainment venues. • Terrorism From Chapter 4 on, the emphasis is on the Response phase and deals with organisation and response techniques in detail. Finally there is a section on terminology and abbreviations. An appendix details a typical disaster pack content. War, the greatest of all man made disasters is not considered in this text.

Molecular dynamics study of response of liquid N,N-dimethylformamide to externally applied electric field using a polarizable force field

The behavior of Liquid N,N-dimethylformamide subjected to a wide range of externally applied electric fields (from 0.001 V/nm to 1 V/nm) has been investigated through molecular dynamics simulation. To approach the objective the AMOEBA polarizable force field was extended to include the interaction of the external electric field with atomic partial charges and the contribution to the atomic polarization. The simulation results were evaluated with quantum mechanical calculations. The results from the present force field for the liquid at normal conditions were compared with the experimental and molecular dynamics results with non-polarizable and other polarizable force fields. The uniform external electric fields of higher than 0.01 V/nm have a significant effect on the structure of the liquid, which exhibits a variation in numerous properties, including molecular polarization, local cluster structure, rotation, alignment, energetics, and bulk thermodynamic and structural properties.

Kinetics of the polarization reversal process in a non-constant applied electric field and the generalized superposition principle

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Electronic Structure Calculations in a 2D SixGe1-x Alloy Under an Applied Electric Field.

The recent advances and promises in nanoscience and nanotechnology have been focused on hexagonal materials, mainly on carbon-based nanostructures. Recently, new candidates have been raised, where the greatest efforts are devoted to a new hexagonal and buckled material made of silicon, named Silicene. This new material presents an energy gap due to spin-orbit interaction of approximately 1.5 meV, where the measurement of quantum spin Hall effect(QSHE) can be made experimentally. Some investigations also show that the QSHE in 2D low-buckled hexagonal structures of germanium is present. Since the similarities, and at the same time the differences, between Si and Ge, over the years, have motivated a lot of investigations in these materials. In this work we performed systematic investigations on the electronic structure and band topology in both ordered and disordered SixGe1-x alloys monolayer with 2D honeycomb geometry by first-principles calculations. We show that an applied electric field can tune the gap size for both alloys. However, as a function of electric field, the disordered alloy presents a W-shaped behavior, similarly to the pure Si or Ge, whereas for the ordered alloy a V-shaped behavior is observed.