Design, Fabrication and Test of a Graphene-Based THz Modulator

One of the most promising approaches to achieve high-speed wireless communication in the terahertz regime is by designing and fabricating devices based on the unique electrical properties of graphene. Certain bands in the THz range (300 GHz – 3 THz) encounter minimal water absorption over short distances and high-speed information transfer is possible. Nonetheless, conventional bulk devices cannot operate at that speed. In the more basic wireless communications system, there are three basic components: a source, a modulator and an antenna. With the use of the Rochester Institute of Technology Semiconductor manufacturing and Fabrication laboratory a graphene-based modulator was designed and fabricated. Electrical testing was performed using the TeraNova THz testbed at the Ultra-Broadband Nano Communication and Networking Lab at the State University of New York at Buffalo. As proof of concept, a passive modulator was preliminary fabricated following a simple capacitor design. The top plate is an aluminum diffraction grating and couples a THz signal to the underlying graphene monolayer, which acts as the bottom plate. This passive graphene-based device showed a 50\% higher absorbance of a 1 THz signal when compared to a device without graphene. The active modulator was then fabricated and tested. Varying the applied DC bias between the aluminum grating and the buried p+ silicon well, modifies the electric field on the graphene layer and its conductivity. It was found to modulate a THz signal by up to 18 dBm when a +24 Volt bias was applied. These are very promising results for future wireless THz communications and provides practical devices for the THz gap

Behaviour of compacted silt used to construct flood embankment

This paper investigates the unsaturated mechanical behaviour of a fill material sampled from flood embankments located along the Bengawan Solo River in Indonesia. In order to gain a better understanding of this fill material, in situ tests were carried out alongside an extensive laboratory programme. Two different phenomena related to changes in moisture content of the embankment fill material are experimentally studied herein: (a) volumetric collapse and (b) variation in shear strength with suction. At low densities, similar to those found in situ, the material exhibited significant volumetric collapse behaviour. Triaxial tests carried out under saturated, suction-controlled and constant water content conditions indicate that the shear strength of the material increased with suction; in particular the effective angle of friction increased from 24.9 degrees under saturated conditions to 35.8 degrees under air-dried conditions

Asymptotic analysis of pollution filtration through thin random fissures between two porous media

We describe the asymptotic behaviour of a filtration problem from a contaminated porous medium to a non-contaminated porous medium through thin vertical fissures of fixed height h>0, of random thinness of order {\epsilon} and which are $\epsilon$-periodically distributed. We compute the limit velocity of the flow and the limit flux of pollutant at the interfaces between the two porous media and the intermediate one

Enhancing in vitro biocompatibility and corrosion protection of organic-inorganic hybrid sol-gel films with nanocrystalline hydroxyapatite

Application of novel organic-inorganic hybrid sol-gel coatings containing dispersed hydroxyapatite (HAp) particles improves the biocompatibility, normal human osteoblast (NHOst) response in terms of osteoblast viability and adhesion of a Ti6Al4V alloy routinely used in medical implants. The incorporation of HAp particles additionally results in more effective barrier proprieties and improved corrosion protection of the Ti6Al4V alloy through higher degree of cross-linking in the organopolysiloxane matrix and enhanced film thickness

Single-atom entropy squeezing for two two-level atoms interacting with a single-mode radiation field

In this paper we consider a system of two two-level atoms interacting with a single-mode quantized electromagnetic field in a lossless resonant cavity via $l$-photon-transition mechanism. The field and the atoms are initially prepared in the coherent state and the excited atomic states, respectively. For this system we investigate the entropy squeezing, the atomic variances, the von Neumann entropy and the atomic inversions for the single-atom case. We show that the more the number of the parties in the system the less the amounts of the nonclassical effects exhibited in the entropy squeezing. The entropy squeezing can give information on the corresponding von Neumann entropy. Also the nonclassical effects obtained form the asymmetric atoms are greater than those obtained form the symmetric atoms. Finally, the entropy squeezing gives better information than the atomic variances only for the asymmetric atoms.Comment: 15 pages, 4 figures, comments are most welcom

Ethylene seems required for the berry development and ripening in grape, a non-climacteric fruit

While the grape has been classified as a non-climacteric fruit whose ripening is thought to be ethylene independent, we show here that a transient increase of endogenous ethylene production occurs just before veraison (i.e. inception of ripening). We observed that ethylene perception, at this time, is required for at least the increase of berry diameter, the decrease of berry acidity and anthocyanin accumulation in the ripening berries; these latter experiments were performed with 1-methylcyclopropene, a specific inhibitor of ethylene receptors. The potential roles of ethylene in berry development and ripening are discussed

APPLICATION OF AN ARTIFICIAL INTELLIGENCE-ENABLED REAL-TIME WARGAMING SYSTEM FOR NAVAL TACTICAL OPERATIONS

The Navy is taking advantage of advances in computational technologies and data analytic methods to automate and enhance tactical decisions to support warfighters in highly complex combat environments. Novel automated techniques offer opportunities for tactical warfighter support through enhanced situational awareness, automated reasoning and problem-solving, and faster decision timelines. This capstone project investigated the use of artificial Intelligence and game theory to develop real-time wargaming capabilities to enhance warfighters in their ability to explore and evaluate the possible consequences of different tactical COAs to improve tactical missions. This project applied a systems analysis approach and developed a conceptual design of a wargaming real-time Artificial Intelligence decision-aid (WRAID) system capability to support the future tactical warfighter. An operational scenario was developed and used to conduct an operational analysis of the WRAID capability. The project identified requirements for the future WRAID capabilities and studied implementation challenges (including ethical) that will need to be addressedNPS Naval Research ProgramThis project was funded in part by the NPS Naval Research Program.Civilian, DoD, NUWCNPTCivilian, Department of the NavyCivilian, Department of the NavyCivilian, Department of the NavyApproved for public release. Distribution is unlimited

Potential of heat pipe technology in nuclear seawater desalination

The official published version of this article can be found at the link below.Heat pipe technology may play a decisive role in improving the overall economics, and public perception on nuclear desalination, specifically on seawater desalination. When coupled to the Low-Temperature Multi-Effect Distillation process, heat pipes could effectively harness most of the waste heat generated in various types of nuclear power reactors. Indeed, the potential application of heat pipes could be seen as a viable option to nuclear seawater desalination where the efficiency to harness waste heat might not only be enhanced to produce larger quantities of potable water, but also to reduce the environmental impact of nuclear desalination process. Furthermore, the use of heat pipe-based heat recovery systems in desalination plant may improve the overall thermodynamics of the desalination process, as well as help to ensure that the product water is free from any contamination which occur under normal process, thus preventing operational failure occurrences as this would add an extra loop preventing direct contact between radiation and the produced water. In this paper, a new concept for nuclear desalination system based on heat pipe technology is introduced and the anticipated reduction in the tritium level resulting from the use of heat pipe systems is discussed

Climatic Drivers of Potential Hazards in Mediterranean Coasts

This paper studies climatic drivers (air and water temperature, precipitation rates, river discharge, sea level and storm patterns) in four Mediterranean regions: the Catalan-Valencia Coast (Spain), the Oran (Algeria) and Gabe`s (Tunisia) Gulfs and the western Nile Delta (Egypt). The paper also considers the potential hazards that these drivers can induce. It first analyses climatic trends in the drivers, taking into account the available time series of recorded and simulated meteo-oceanographic data from different sources. Next, it presents the general framework to assess biogeophysical hazards (flooding, erosion, droughts and water quality), followed by a simple and yet robust evaluation of those hazards for the four studied coastal sites. Assuming climate change projections under different scenarios and considering the observed trends in drivers, the resulting erosion rates due to sea-level rise and wave storm effects have been estimated. The Nile and Ebro Deltas, together with the Oran Gulf, are more vulnerable than the Gulfs of Valencia and Gabe`s. Regarding water quality in terms of (a) precipitation and dissolved oxygen in the water column and (b) sea surface temperature, the results show that the most vulnerable zones for the projected conditions (a) are the Gulfs of Oran, Valencia and Gabe`s, while the Nile Delta is the region where the decrease in water quality will be less pronounced. For the projected conditions (b), the most vulnerable zone is the Ebro Delta, while the impact in the other three cases will be smaller and of comparable magnitude. Finally, the overall future impact of these hazards (associated to climatic change) in the four sites is discussed in comparative terms, deriving some conclusions

Suspended silicon integrated platform for the long-wavelength mid-infrared band

The atmospheric-transmission window and the fingerprint region of many substances overlaps with the long-wave infrared band. This has enabled the emergence of a new path for photonic integrated circuits, which could exploit the potential applications of this wavelength range, including chemical and bio sensing. In this work we review our latest advances in the suspended silicon platform with subwavelength grating lateral cladding at 7.7-µm wavelength. Suspended waveguides only require one lithographic etch step and can be specifically designed to maximize sensitivity when used as sensors. Waveguides with propagation loss of 3.1±0.3 dB/cm are demonstrated, as well as bends with less than 0.1 dB/bend. Suspended waveguides based on shifted Bragg grating lateral cladding are also reported, with propagation loss of 5.1±0.6 dB/cm. These results prepare the ground for the development of a platform capable of covering the entire mid-infrared band. Keywords: suspended silicon, mid-infrared, long-wave infrared, subwavelength grating, Bragg.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech