59 research outputs found
Statistical assessment on Non-cooperative Target Recognition using the Neyman-Pearson statistical test
Electromagnetic simulations of a X-target were performed in order to obtain its Radar Cross
Section (RCS) for several positions and frequencies. The software used is the CST MWS©. A 1 : 5
scale model of the proposed aircraft was created in CATIA© V5 R19 and imported directly into
the CST MWS© environment. Simulations on the X-band were made with a variable mesh size
due to a considerable wavelength variation. It is intended to evaluate the Neyman-Pearson (NP)
simple hypothesis test performance by analyzing its Receiver Operating Characteristics (ROCs)
for two different radar detection scenarios - a Radar Absorbent Material (RAM) coated model,
and a Perfect Electric Conductor (PEC) model for recognition purposes.
In parallel the radar range equation is used to estimate the maximum range detection for the
simulated RAM coated cases to compare their shielding effectiveness (SE) and its consequent
impact on recognition. The AN/APG-68(V)9’s airborne radar specifications were used to compute
these ranges and to simulate an airborne hostile interception for a Non-Cooperative Target
Recognition (NCTR) environment. Statistical results showed weak recognition performances
using the Neyman-Pearson (NP) statistical test. Nevertheless, good RCS reductions for most of
the simulated positions were obtained reflecting in a 50:9% maximum range detection gain for
the PAniCo RAM coating, abiding with experimental results taken from the reviewed literature.
The best SE was verified for the PAniCo and CFC-Fe RAMs.Simulações electromagnéticas do alvo foram realizadas de modo a obter a assinatura radar (RCS)
para várias posições e frequĂŞncias. O software utilizado Ă© o CST MWS©. O modelo proposto Ă
escala 1:5 foi modelado em CATIA© V5 R19 e importado diretamente para o ambiente de trabalho
CST MWS©. Foram efectuadas simulações na banda X com uma malha de tamanho variável
devido à considerável variação do comprimento de onda. Pretende-se avaliar estatisticamente
o teste de decisĂŁo simples de Neyman-Pearson (NP), analisando as CaracterĂsticas de Operação
do Receptor (ROCs) para dois cenários de detecção distintos - um modelo revestido com material
absorvente (RAM), e outro sendo um condutor perfeito (PEC) para fins de detecção.
Em paralelo, a equação de alcance para radares foi usada para estimar o alcance máximo de
detecção para ambos os casos de modo a comparar a eficiência de blindagem electromagnética
(SE) entre os diferentes revestimentos. As especificações do radar AN/APG-68(V)9 do F-16 foram
usadas para calcular os alcances para cada material, simulando uma intercepção hostil num
ambiente de reconhecimento de alvos nĂŁo-cooperativos (NCTR). Os resultados mostram performances
de detecção fracas usando o teste de decisão simples de Neyman-Pearson como detector
e uma boa redução de RCS para todas as posições na gama de frequências selecionada. Um ganho
de alcance de detecção máximo 50:9 % foi obtido para o RAM PAniCo, estando de acordo com
os resultados experimentais da bibliografia estudada. Já a melhor SE foi verificada para o RAM
CFC-Fe e PAniCo
Langley Aerospace Research Summer Scholars
The Langley Aerospace Research Summer Scholars (LARSS) Program was established by Dr. Samuel E. Massenberg in 1986. The program has increased from 20 participants in 1986 to 114 participants in 1995. The program is LaRC-unique and is administered by Hampton University. The program was established for the benefit of undergraduate juniors and seniors and first-year graduate students who are pursuing degrees in aeronautical engineering, mechanical engineering, electrical engineering, material science, computer science, atmospheric science, astrophysics, physics, and chemistry. Two primary elements of the LARSS Program are: (1) a research project to be completed by each participant under the supervision of a researcher who will assume the role of a mentor for the summer, and (2) technical lectures by prominent engineers and scientists. Additional elements of this program include tours of LARC wind tunnels, computational facilities, and laboratories. Library and computer facilities will be available for use by the participants
In Search of the DomoNovus: Speculative Designs for the Computationally-Enhanced Domestic Environment
Edited version embargoed until 01.02.2018
Full version: Access restricted permanently due to 3rd party copyright restrictions. Restriction set on 01.02.2017 by SC, Graduate schoolThe home is a physical place that provides isolation, comfort, access to essential needs on a daily basis, and it has a strong impact on a person’s life. Computational and media technologies (digital and electronic objects, devices, protocols, virtual spaces, telematics, interaction, social media, and cyberspace) become an important and vital part of the home ecology, although they have the ability to transform the domestic experience and the understanding of what a personal space is.
For this reason, this work investigates the domestication of computational media technology; how objects, systems, and devices become part of the personal and intimate space of the inhabitants. To better understand the taming process, the home is studied and analysed from a range of perspectives (philosophy, sociology, architecture, art, and technology), and a methodological process is proposed for critically exploring the topic with the development of artworks, designs, and computational systems.
The methodology of this research, which consists of five points (Context, Media Layers, Invisible Matter, Diffusion, and Symbiosis), suggests a procedure that is fundamental to the development and critical integration of the computationally enhanced home. Accordingly, the home is observed as an ecological system that contains numerous properties (organic, inorganic, hybrid, virtual, augmented), and is viewed on a range of scales (micro, meso and macro). To identify the “choreographies” that are formed between these properties and scales, case studies have been developed to suggest, provoke, and speculate concepts, ideas, and alternative realities of the home. Part of the speculation proposes the concept of DomoNovus (the “New Home”), where technological ubiquity supports the inhabitants’ awareness, perception, and imagination. DomoNovus intends to challenge our understanding of the domestic environment, and demonstrates a range of possibilities, threats, and limitations in relation to the future of home.
This thesis, thus, presents methods, experiments, and speculations that intend to inform and inspire, as well as define creative and imaginative dimensions of the computationally-enhanced home, suggesting directions for the further understanding of the domestic life.Alexander S. Onassis Public Benefit Foundatio
Dimensional Dependence of Light Interaction with Nanowires
Semiconductor nanowires have been used in a variety of passive and active optoelectronic devices including waveguides, photodetectors, solar cells, LEDs, Lasers, sensors, and optical antennas. We examine GaAs/AlGaAs core-shell nanowires (CSNWs) grown on both GaAs and Si substrates by vapor-liquid-solid (VLS) method followed by Metal-Organic Chemical Vapor Deposition (MOCVD). These nanowires show extremely enhanced optical properties in terms of absorption, guiding, radiation of light, and even lasing. For the wavelength range of 700-1200nm these core-shells which only occupy 15% of the volume compared to thin films of the same height, reflect 2-4% of light for the CSNWs grown on Si, and 3-7% of light for those grown on GaAs substrate. The photoluminescence (PL) spectrum shows 923 times more light emitted from CSNWs grown on GaAs compared to bulk GaAs at room temperature, and optical pumped lasing with threshold of around 5 microwatt, followed by saturation near 12 microwatt. In addition, as-measured full-width half-max (FWHM) of ~13 ps time response has been demonstrated for CSNW using Electro-Optically Sampling (EOS) measurement. Analysis of the interaction of light with cylindrical and hexagonal structures with sub-wavelength diameters identifies both transverse and longitudinal plane modes which we generalize to volumetric resonant modes, importantly, without the need for vertical structures such as Bragg mirrors commonly used in vertical cavity surface emitting lasers (VCSEL's). We report on FDTD simulations with the aim of identifying the dependence of these modes on geometry (length, width), tapering, shape (cylindrical, hexagonal), core-shell versus core-only, and dielectric cores with semiconductor shells. This demonstrates how NWs form excellent optical cavities without the need for top and bottom mirrors. However, optically equivalent structures such as hexagonal and cylindrical wires can have very different optoelectronic properties meaning that light management alone does not sufficiently describe the observed enhancement in upward (absorption) and downward transitions (emission) of light in nanowires, rather, the electronic transition rates should be considered. Using Fermi's Golden Rule in interaction of light and matter, we discuss how the transition rates change due to electronic wave function and identify three factors, namely, oscillator strength, overlap functions, and the joint optical density of states(JDOS), explicitly contributing to the transition rates with strong dependence on dimensionality. We apply these results to the study of lasing in as-grown CSNW on Si & GaAs and discuss how these subwavelength structures can have enhanced optical gain, quantum efficiency and 175 times more optical output power compared to their bulk counterparts despite their large > 200nm geometries. These results and findings will further facilitate the design and optimization of sub-micron scale optoelectronic devices. In conclusion, we make a case for photonic integrated circuits that can take advantage of the confluence of the desirable optical and electronic properties of these nanostructures.Ph.D., Electrical Engineering -- Drexel University, 201
Proceedings of the Fifth International Mobile Satellite Conference 1997
Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial communications services. While previous International Mobile Satellite Conferences have concentrated on technical advances and the increasing worldwide commercial activities, this conference focuses on the next generation of mobile satellite services. The approximately 80 papers included here cover sessions in the following areas: networking and protocols; code division multiple access technologies; demand, economics and technology issues; current and planned systems; propagation; terminal technology; modulation and coding advances; spacecraft technology; advanced systems; and applications and experiments
Fibre optic pressure sensors in healthcare applications
This PhD thesis provides an extensive description of the development of two fibre optic pressure sensors for applications in health care: (i) a miniature fibre optic Fabry–Perot pressure sensor for fluid pressure measurements in invasive blood pressure monitoring and; (ii) a highly sensitive fibre Bragg grating sensor for contact/interface pressure measurement.
The fibre optic Fabry-Perot pressure sensor has a diameter of 125 μm and is created by forming a cavity at the tip of a single-mode optical fibre. Parylene films were used as the pressure-sensitive diaphragm. The performance of three sensors with different aspect ratios has been investigated. The pressure sensing range of ~10 kPa (diastolic pressure)- ~15 kPa (systolic pressure) was targeted; sensor with the cavity of 70 μm in diameter and cavity length of 87 μm is able to sense within a range of 0- 18 kPa with an average sensitivity of 0.12 nm/kPa and response time of 3 seconds. The temperature sensitivity of 0.084 nm/°C was observed. Hysteresis and wavelength drift were observed for the sensors, which may be due to the permeability of the Parylene film to the air. Solutions for reducing hysteresis, wavelength drift and temperature cross-sensitivity are discussed in detail.
Fibre Bragg grating (FBG) sensor technology is an ideal candidate for contact pressure measurement in compression therapy, pressure ulcer or prosthetics due to its many advantages such as conforming to body parts, small size, biocompatibility and multiplexing capabilities. A successful mathematical model for an FBG contact pressure sensor for healthcare applications has been presented and experimentally validated. The model has been compared with previous studies reported in the literature and takes into account birefringence. The highest sensitivity was achieved for the disc shape with a sensitivity of 0.8719 nm/MPa for a diameter of 5.5 mm, thickness of 1 mm and Young’s modulus of 20 MPa. This sensor was comprised of a 3 mm long FBG
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centrally located in the patch. This is a pressure sensitivity of ~270 times increase when compared with a bare FBG reported in the literature. Birefringence effect was observed for the disk patch for pressures larger than 2.6 MPa.
Even though FBGs provide high sensitivity in contact pressure sensing in healthcare, the potential applications are limited by the size and cost of commercially available FBG interrogators. A successful first attempt towards the development of a single channel compact FBG interrogation was accomplished. The system consists of a three-section distributed Bragg Reflector (DBR) tuneable laser, microcontroller unit, precision 5 channel current driver IC, photodiode circuit and a temperature controller IC. The tuneable laser was calibrated within 1535-1544 nm wavelength range to produce three current–wavelength lookup tables for wavelength resolution of 1 nm, 0.1 nm, 0.01 nm which is dependent on the current resolution. Futureworkincludesaddingpowercircuitry, a photodiode circuit and a feedback circuit to minimize power fluctuations. The system was tested compared to the commercial Smartscope FBG interrogator
Aquasomes as a drug delivery system for proteins and peptides
Aquasomes are nanocarrier systems consist of three distinctive layers; an inner core, a polyhydroxy carbohydrate layer and an outer layer of an API (Kossovsky et al., 1991). Aquasomes have a unique structure and ability to carry active molecules through a non-covalent bounding and provide superior stability, especially for proteins and peptides (Masatoshi and Yongning, 1998; Kim and Kim, 2002; Khopade et al., 2002). Different core and coating materials were used to prepare aquasomes under different conditions to investigate the relationship between preparation conditions and loading efficiency. In terms of loading efficiency, hydroxyapatite aquasomes, with either lactose or trehalose as a coating material, had the highest BSA loading (40%-60%) when compared to DSPA aquasomes. While DCPA aquasomes, with either lactose or trehalose as a coating material, had the lowest BSA loading (8%-16%). To investigate the interaction of the three layers of aquasomes, Surface analysis, docking and MD simulations were performed. Surface analysis performed by Discovery Studio showed that HA and trehalose interact by hydrogen bonding with the later acting as a hydrogen acceptor, while BSA displayed almost complete SAS and that there are numerous targets for trehalose attachments (no specific active site). MD simulations of BSA performed by AMBER 12 showed a stable MD simulation of BSA for 5 ns. Total energy analysis of BSA on the two conditions performed (300K and 280K) support the experimental data of lower BSA loadings of aquasomes prepared at 400C compared to those manufactured at 250C (p5.5 and steadily release for 6 hr. Cell culture studies were conducted to demonstrate the controlled release effect of aquasomes using Caco-2 cell lines. The release of metronidazole (model drug) from aquasomes post 2 hr started to slow gradually until it reached its highest difference at 6 hr (p<0.05) when compared to the control
Change blindness: eradication of gestalt strategies
Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task
Full Proceedings, 2018
Full conference proceedings for the 2018 International Building Physics Association Conference hosted at Syracuse University
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