On-board processing satellite network architecture and control study

The market for telecommunications services needs to be segmented into user classes having similar transmission requirements and hence similar network architectures. Use of the following transmission architecture was considered: satellite switched TDMA; TDMA up, TDM down; scanning (hopping) beam TDMA; FDMA up, TDM down; satellite switched MF/TDMA; and switching Hub earth stations with double hop transmission. A candidate network architecture will be selected that: comprises multiple access subnetworks optimized for each user; interconnects the subnetworks by means of a baseband processor; and optimizes the marriage of interconnection and access techniques. An overall network control architecture will be provided that will serve the needs of the baseband and satellite switched RF interconnected subnetworks. The results of the studies shall be used to identify elements of network architecture and control that require the greatest degree of technology development to realize an operational system. This will be specified in terms of: requirements of the enabling technology; difference from the current available technology; and estimate of the development requirements needed to achieve an operational system. The results obtained for each of these tasks are presented

S and U-duality Constraints on IIB S-matrices

S and U-duality dictate that graviton scattering amplitudes in IIB superstring theory be automorphic functions on the appropriate fundamental domain which describe the inequivalent vacua of (compactified) theories. A constrained functional form of graviton scattering is proposed using Eisenstein series and their generalizations compatible with: a) two-loop supergravity, b) genus one superstring theory, c) the perturbative coupling dependence of the superstring, and d) with the unitarity structure of the massless modes. The form has a perturbative truncation in the genus expansion at a given order in the derivative expansion. Comparisons between graviton scattering S-matrices and effective actions for the first quantized superstring are made at the quantum level. Possible extended finiteness properties of maximally extended quantum supergravity theories in different dimensions is implied by the perturbative truncation of the functional form of graviton scattering in IIB superstring theory.Comment: 36 pages, 5 figures, LaTeX, (minor) eq. corr., to appear in NP

Bespoke high-fidelity visualization of tiling

This paper describes the development and validation of a new service allowing products, such as tiles, to be viewed on a computer authentically in the actual lighting conditions of the area in which they are to be installed. This service leverages recent developments in physically based global illumination and High Dynamic Range (HDR) imaging, enabling real-world lighting to be accurately captured, transferred to a computer and used to relight any choice of tile in a highly realistic manner.This project is funded by TSB ICT for Manufacturing and Construction project 14345-87267. The project is also partially supported by ICT COST Action IC1005. L. P. Santos is partially funded through the FCT (Portuguese Foundation for Science and Technology) within project PEst-OE/EEI/UI0752/2011

Selective BRDFs for High Fidelity Rendering

High fidelity rendering systems rely on accurate material representations to produce a realistic visual appearance. However, these accurate models can be slow to evaluate. This work presents an approach for approximating these high accuracy reflectance models with faster, less complicated functions in regions of an image which possess low visual importance. A subjective rating experiment was conducted in which thirty participants were asked to assess the similarity of scenes rendered with low quality reflectance models, a high quality data-driven model and saliency based hybrids of those images. In two out of the three scenes that were evaluated significant differences were not found between the hybrid and reference images. This implies that in less visually salient regions of an image computational gains can be achieved by approximating computationally expensive materials with simpler analytic models

Audio-visual-olfactory resource allocation for tri-modal virtual environments

© 2019 IEEE. Virtual Environments (VEs) provide the opportunity to simulate a wide range of applications, from training to entertainment, in a safe and controlled manner. For applications which require realistic representations of real world environments, the VEs need to provide multiple, physically accurate sensory stimuli. However, simulating all the senses that comprise the human sensory system (HSS) is a task that requires significant computational resources. Since it is intractable to deliver all senses at the highest quality, we propose a resource distribution scheme in order to achieve an optimal perceptual experience within the given computational budgets. This paper investigates resource balancing for multi-modal scenarios composed of aural, visual and olfactory stimuli. Three experimental studies were conducted. The first experiment identified perceptual boundaries for olfactory computation. In the second experiment, participants (N=25) were asked, across a fixed number of budgets (M=5), to identify what they perceived to be the best visual, acoustic and olfactory stimulus quality for a given computational budget. Results demonstrate that participants tend to prioritize visual quality compared to other sensory stimuli. However, as the budget size is increased, users prefer a balanced distribution of resources with an increased preference for having smell impulses in the VE. Based on the collected data, a quality prediction model is proposed and its accuracy is validated against previously unused budgets and an untested scenario in a third and final experiment

A Calibrated Olfactory Display for High Fidelity Virtual Environments

Olfactory displays provide a means to reproduce olfactory stimuli for use in virtual environments. Many of the designs produced by researchers, strive to provide stimuli quickly to users and focus on improving usability and portability, yet concentrate less on providing high levels of accuracy to improve the fidelity of odour delivery. This paper provides the guidance to build a reproducible and low cost olfactory display which is able to provide odours to users in a virtual environment at accurate concentration levels that are typical in everyday interactions; this includes ranges of concentration below parts per million and into parts per billion. This paper investigates build concerns of the olfactometer and its proper calibration in order to ensure concentration accuracy of the device. An analysis is provided on the recovery rates of a specific compound after excitation. This analysis provides insight into how this result can be generalisable to the recovery rates of any volatile organic compound, given knowledge of the specific vapour pressure of the compound

Open string field theory without open strings

Witten's cubic open string field theory is expanded around the perturbatively stable vacuum, including all scalar fields at levels 0, 2, 4 and 6. The (approximate) BRST cohomology of the theory is computed, giving strong evidence for the absence of physical open string states in this vacuum.Comment: 12 pages, 1 figure, LaTeX; v2: reference adde

On the supermultiplet of anomalous currents in d=6

The multiplet of superconformal anomalous currents in the case $(1,0)$, $d=6$ is derived. The supersymmetric multiplet of anomalies contains the trace of the energy momentum tensor, the gamma trace of the supercurrent and some topological vector current with divergence equal to the $R$-current anomaly. The extension of this consideration to the $(2,0)$ case and some application and motivation coming from $AdS_{7}/CFT_{6}$ correspondence is discussed.Comment: Latex, 14 page

Impact of treatment strategies on cephalosporin and tetracycline resistance gene quantities in the bovine fecal metagenome

The study objective was to determine the effects of two treatment regimens on quantities of ceftiofur and tetracycline resistance genes in feedlot cattle. The two regimens were ceftiofur crystalline-free acid (CCFA) administered to either one or all steers within a pen and subsequent feeding/not feeding of therapeutic doses of chlortetracycline. A 26-day randomized controlled field trial was conducted on 176 steers. Real-time PCR was used to quantify bla[subscript CMY-2], bla[subscript CTX-M], tet(A), tet(B), and 16S rRNA gene copies/gram of feces from community DNA. A significant increase in ceftiofur resistance and a decrease in tetracycline resistance elements were observed among the treatment groups in which all steers received CCFA treatment, expressed as gene copies/gram of feces. Subsequent chlortetracycline administration led to rapid expansion of both ceftiofur and tetracycline resistance gene copies/gram of feces. Our data suggest that chlortetracycline is contraindicated when attempting to avoid expansion of resistance to critically important third-generation cephalosporins