[en] Securing radioactive materials from across their life-cycle is a large collaborative effort that involves all levels of officials, policymakers, operational stakeholders, and local law enforcement. Both domestic and international cooperation is crucial to the prevention and detection of criminal/ unauthorized acts involving nuclear and other radioactive materials. Gathering all parties involved in the same room to evoke communication and collaborate presents both a logistical challenge and requires a great deal of time and resources. With new and emerging technologies in mixed reality, this communication, collaboration and visualization can be done remotely and can include tools to help enhance these types of collaborative tabletop exercises. Our Scribe 3D Tabletop Tool is a visually rich software package that enhances tabletop exercises by providing a set of tools to visualize and record all events, actions, and discussions during a tabletop exercise. It provides an environment which organizes and evokes discussion allowing for a more comprehensive tabletop experience. As a tabletop exercise is conducted, a scenario is developed and recorded allowing users to visually play back the scenario and information all within a 3D environment. Because the scenario playback is within a 3D environment and not just a video, it allows users to take various view points and perspectives. All decision-making points are recorded for every event and engagement as well as the outcomes of those engagements. This enables the organization and review of decision making points to improve results and outcomes. Currently, Scribe 3D is being used by ORS to enhance tabletop exercises but does not include a radioactive source model visualization or a mixed reality experience for collaboration. This mixed reality experience includes: • the ability for users to be immerse in the execution of a 3D table top scenario • interact with the terrain and entities • place themselves on the ground to watch a scenario unfold in first person Enhancing the current Scribe 3D Tabletop tool with these features presents a significant improvement for use in the nuclear and other radioactive material security communities that conduct these exercises. At the 2018 IAEA International Conference, a talk on this concept will be presented, as well as an interactive demonstration of the mixed reality experience as explained above. (author)

[en] This PowerPoint presentation provided a look at the deregulated market in Texas. The Electric Reliability Council of Texas (ERCOT) was created in 1970 to establish and monitor the reliability of Texas systems. In 1996, ERCOT became an Independent System Operator (ISO). The author explained the governance adopted by ERCOT. Originally, the Board consisted of 22 members, but market segment representation was reduced in December, leaving 14 members. The Board's mandate is to provide guidance and direction to the staff of the ISO. Senate Bill 7 was discussed, which became law in 1999. It required the creation of a competitive retail electricity market. It also required: open access to transmission and distribution systems, reliability, timely conveyance of information needed to support customer choice, and accurate accountability for electricity production and delivery. Market design was described and observations added. The author concluded that wholesale operations remain solid and that all grids are subject to disturbances. One of the biggest challenges is transmission. Despite start-up problems, retail operations are progressing well. tabs., figs

[en] We present a terrestrial measurement of the Lande g factor of the 5D_5/2 state of singly ionized barium. Measurements were performed on single Doppler-cooled ¹³⁸Ba⁺ ions in a linear Paul trap. A frequency-stabilized fiber laser with a nominal wavelength of 1.762 μm was scanned across the 6S_1/2↔5D_5/2 transition to spectroscopically resolve transitions between Zeeman sublevels of the ground and excited states. From the relative positions of the four narrow transitions observed at several different values for the applied magnetic field, we find a value of 1.2020±0.0005 for g_5D5/2.

[en] State preparation, qubit rotation, and high fidelity readout are demonstrated for two different ¹³⁷Ba⁺ qubit types. First, an optical qubit on the narrow 6S_1/2 to 5D_5/2 transition at 1.76 μm is implemented. Then, leveraging the techniques developed there for readout, a ground-state hyperfine qubit using the magnetically insensitive transition at 8 GHz is accomplished.

[en] A technique capable of detecting the instantaneous, time-resolved, 3D flame topography is successfully demonstrated in a lean-premixed swirl flame undergoing flashback. A simultaneous measurement of the volumetric velocity field is possible without the need for additional hardware. Droplets which vaporize in the preheat zone of the flame serve as the marker for the flame front. The droplets are illuminated with a laser and imaged from four different views followed by a tomographic reconstruction to obtain the volumetric particle field. Void regions in the reconstructed particle field, which correspond to regions of burnt gas, are detected with a series of image processing steps. The interface separating the void region from regions filled with particles is defined as the flame surface. The velocity field in the unburnt gas is measured using tomographic PIV. The resulting data include the simultaneous 3D flame front and 3D volumetric velocity field at 5 kHz. The technique is applied to a lean-premixed (ϕ  =  0.8), swirling methane-air flame and validated against simultaneously acquired planar measurements. The mean error associated with the reconstructed 3D flame topography is about 0.4 mm, which is smaller than the flame thickness under the studied conditions. The mean error associated with the volumetric velocity field is about 0.2 m s"−"1. (paper)

[en] Investigations of thin film depositions of silicon carbide (SiC) from pulse sputtering a hollow cathode SiC target are presented. The unique feature of the hollow cathode technique is that germanium can be added to the films. This changes the properties of the SiC. Such changes include evidence of Ge-C bonds, lowering of the resistivity, and lowering of the bandgap. The analysis includes crystallographic and morphological studies of the deposited films and their quality using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy data. Basic electrical properties are also presented along with optical bandgap information gathered from spectroscopic ellipsometry data.

[en] The operation of pulsed-plasma actuators for flow control is often associated with the presence of charged species in the flow and severe electromagnetic interference with external circuitry. These effects can lead to time-resolved transducer pressure measurements that are contaminated with electromagnetic interference effects or even transducer damage due to the interaction with charged species. A new technique is developed that enables high-bandwidth pressure measurements to be made in the presence of such rapidly switched plasma actuators. The technique is applied for the specific configuration of a pulsed-plasma jet actuator (spark jet) that is used to control the unsteadiness of a shock wave/boundary layer interaction generated by a compression ramp in a Mach 3 flow. The critical component of the technique involves using a pulsed-ground electrode to drain the charged species from the plasma jet before they reach the pressure transducer. The pulsed-ground electrode was shown to drain charged species into the pulsed ground prior to interacting with the transducer, which made it possible to make measurements without damaging the transducer. The resulting signals were still contaminated by electromagnetic interference spikes and so a data-processing technique was used to remove the artifacts and recover a largely uncontaminated power spectrum. The signal processing scheme used interpolation schemes previously developed for laser Doppler velocimetry applications. The data-processing procedure is demonstrated with a benchmark case in which the electromagnetic interference was isolated from the pulsed-plasma jet actuation effect. It is shown that the data-processing procedure removed the contamination from the electromagnetic interference at all frequencies but for the pulsing frequency and its higher harmonics

[en] Flashback of premixed methane–air flames in the turbulent boundary layer of swirling flows is investigated experimentally. The premix section of the atmospheric model swirl combustor features an axial swirler with an attached center-body. Our previous work with this same configuration investigated the flame propagation during flashback using particle image velocimetry (PIV) with liquid droplets as seed particles that precluded making measurements in the burnt gases. The present study investigates the transient velocity field in the unburnt and burnt gas region by means of solid-particle seeding and high-speed stereoscopic PIV. The global axial and circumferential lab-frame flame propagation speed is obtained simultaneously based on high-speed chemiluminescence movies. By combining the PIV data with the global flame propagation speed, the quasi-instantaneous swirling motion of the velocity field is constructed on annular shells, which provides a more intuitive view on the complex three-dimensional flow–flame interaction. Previous works showed that flashback is led by flame tongues. We find that the important flow–flame interaction occurs on the far side of these flame tongues relative to the approach flow, which we henceforth refer to as the leading side. The leading side is found to propagate as a classical premixed flame front relative to the strongly modified approach flow field. The blockage imposed by flame tongues is not limited to the immediate vicinity of the flame base, but occurs along the entire leading side.

[en] The three-dimensional interfacial grain boundary network in a fully austenitic high-manganese steel was studied as a function of all five macroscopic crystallographic parameters (i.e. lattice misorientation and grain boundary plane normal) using electron backscattering diffraction mapping in conjunction with focused ion beam serial sectioning. The relative grain boundary area and energy distributions were strongly influenced by both the grain boundary plane orientation and the lattice misorientation. Grain boundaries terminated by (1 1 1) plane orientations revealed relatively higher populations and lower energies compared with other boundaries. The most frequently observed grain boundaries were {1 1 1} symmetric twist boundaries with the Σ3 misorientation, which also had the lowest energy. On average, the relative areas of different grain boundary types were inversely correlated to their energies. A comparison between the current result and previously reported observations (e.g. high-purity Ni) revealed that polycrystals with the same atomic structure (e.g. face-centered cubic) have very similar grain boundary character and energy distributions

[en] A fast, simple procedure is described for obtaining an assembly of silver sulfide nanoparticles (Ag₂S NPs) on a glass substrate through reaction of a template of an assembled layer of silver nanoparticles (Ag NPs) with hydrogen sulfide (H₂S) gas. The Ag NP template was prepared by assembling a monolayer of spherical Ag NPs (mean diameter of 7.4 nm) on a polyethylenimine-treated glass substrate. Exposure to pure H₂S for 10 min converted the Ag NPs of the template to Ag₂S NPs. The resulting Ag₂S NP assembly, which retains the template nanostructure and particle distribution, was characterized by optical absorption spectroscopy, atomic force microscopy, transmission electron microscopy (TEM), scanning high resolution TEM, energy dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. The Ag₂S NPs have a crystal structure of monoclinic acanthite, and while they retained the spherical shape of the original Ag NPs, their mean particle size increased to 8.4 nm due to changes to the crystal structure when the Ag NPs are converted into Ag₂S NPs. The measured optical absorption edge of the Ag₂S NP assembly indicated an indirect interband transition with a band gap energy of 1.71 eV. The Ag₂S NP assembly absorbed light with wavelengths below 725 nm, and the absorbance increased monotonically toward the UV region.