Micromachined Millimeter- and Submillimeter-wave SIS Heterodyne Receivers for Remote Sensing

NASA Technical Reports Server (NTRS)

Hu, Qing

1997-01-01

This is a progress report for the second year of a NASA-sponsored project. The report discusses the design and fabrication of micromachined Superconductor Insulator Superconductor (SIS) heterodyne receivers with integrated tuning elements. These receivers tune out the functional capacitance at desired frequencies, resulting in less noise, lower temperatures and broader bandwidths. The report also discusses the design and fabrication of the first monolithic 3x3 focal-plane arrays for a frequency range of 170-210 GHz. Also addressed is the construction of a 9-channel bias and read-out system, as well as the redesign of the IF connections to reduce cross talk between SIS junctions, which become significant a frequency of 1.5 GHz IF. Uniformity of the junction arrays were measured and antenna beam patterns of several array elements under operating conditions also were measured. Finally, video and heterodyne responses of our focal-plane arrays were measured as well. Attached is a paper on: 'Development of a 170-210 GHz 3x3 micromachined SIS imaging array'.

A New Approach to Identify Optimal Properties of Shunting Elements for Maximum Damping of Structural Vibration Using Piezoelectric Patches

NASA Technical Reports Server (NTRS)

Park, Junhong; Palumbo, Daniel L.

2004-01-01

The use of shunted piezoelectric patches in reducing vibration and sound radiation of structures has several advantages over passive viscoelastic elements, e.g., lower weight with increased controllability. The performance of the piezoelectric patches depends on the shunting electronics that are designed to dissipate vibration energy through a resistive element. In past efforts most of the proposed tuning methods were based on modal properties of the structure. In these cases, the tuning applies only to one mode of interest and maximum tuning is limited to invariant points when based on den Hartog's invariant points concept. In this study, a design method based on the wave propagation approach is proposed. Optimal tuning is investigated depending on the dynamic and geometric properties that include effects from boundary conditions and position of the shunted piezoelectric patch relative to the structure. Active filters are proposed as shunting electronics to implement the tuning criteria. The developed tuning methods resulted in superior capabilities in minimizing structural vibration and noise radiation compared to other tuning methods. The tuned circuits are relatively insensitive to changes in modal properties and boundary conditions, and can applied to frequency ranges in which multiple modes have effects.

Adaptive tuned vibration absorber based on magnetorheological elastomer-shape memory alloy composite

NASA Astrophysics Data System (ADS)

Kumbhar, Samir B.; Chavan, S. P.; Gawade, S. S.

2018-02-01

Shape memory alloy (SMA) is an attractive smart material which could be used as stiffness tuning element in adaptive tuned vibration absorber (ATVA). The sharp modulus change in SMA material during phase transformation creates difficulties for smooth tuning to track forcing frequency to minimize vibrations of primary system. However, high hysteresis damping at low temperature martensitic phase degrades performance of vibration absorber. This paper deals with the study of dynamic response of system in which SMA and magnetorheological elastomer (MRE) are combined together to act as a smart spring- mass-damper system in a tuned vibration absorber. This composite is used as two way stiffness tuning element in ATVA for smooth and continuous tuning and to minimize the adverse effect at low temperature by increasing equivalent stiffness. The stiffnesses of SMA element and MRE are varied respectively by changing temperature and strength of external magnetic field. The two way stiffness tuning ability and adaptivity have been demonstrated analytically and experimentally. The experimental results show good agreement with analytical results. The proposed composite is able to shift the stiffness consequently the natural frequency of primary system as well as reduce the vibration level of primary system by substantial mount.

On the accuracy of ERS-1 orbit predictions

NASA Technical Reports Server (NTRS)

Koenig, Rolf; Li, H.; Massmann, Franz-Heinrich; Raimondo, J. C.; Rajasenan, C.; Reigber, C.

1993-01-01

Since the launch of ERS-1, the D-PAF (German Processing and Archiving Facility) provides regularly orbit predictions for the worldwide SLR (Satellite Laser Ranging) tracking network. The weekly distributed orbital elements are so called tuned IRV's and tuned SAO-elements. The tuning procedure, designed to improve the accuracy of the recovery of the orbit at the stations, is discussed based on numerical results. This shows that tuning of elements is essential for ERS-1 with the currently applied tracking procedures. The orbital elements are updated by daily distributed time bias functions. The generation of the time bias function is explained. Problems and numerical results are presented. The time bias function increases the prediction accuracy considerably. Finally, the quality assessment of ERS-1 orbit predictions is described. The accuracy is compiled for about 250 days since launch. The average accuracy lies in the range of 50-100 ms and has considerably improved.

Active noise control using noise source having adaptive resonant frequency tuning through stiffness variation

NASA Technical Reports Server (NTRS)

Rajiyah, Harindra (Inventor); Hedeen, Robert A. (Inventor); Pla, Frederic G. (Inventor); Renshaw, Anthony A. (Inventor)

1995-01-01

A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of a noise radiating element is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating element is tuned by a plurality of force transmitting mechanisms which contact the noise radiating element. Each one of the force transmitting mechanisms includes an expandable element and a spring in contact with the noise radiating element so that excitation of the element varies the spring force applied to the noise radiating element. The elements are actuated by a controller which receives input of a signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the elements and causes the spring force applied to the noise radiating element to be varied. The force transmitting mechanisms can be arranged to either produce bending or linear stiffness variations in the noise radiating element.

Method and apparatus for powering an electrodeless lamp with reduced radio frequency interference

DOEpatents

Simpson, James E.

1999-01-01

An electrodeless lamp waveguide structure includes tuned absorbers for spurious RF signals. A lamp waveguide with an integral frequency selective attenuation includes resonant absorbers positioned within the waveguide to absorb spurious out-of-band RF energy. The absorbers have a negligible effect on energy at the selected frequency used to excite plasma in the lamp. In a first embodiment, one or more thin slabs of lossy magnetic material are affixed to the sidewalls of the waveguide at approximately one quarter wavelength of the spurious signal from an end wall of the waveguide. The positioning of the lossy material optimizes absorption of power from the spurious signal. In a second embodiment, one or more thin slabs of lossy magnetic material are used in conjunction with band rejection waveguide filter elements. In a third embodiment, one or more microstrip filter elements are tuned to the frequency of the spurious signal and positioned within the waveguide to couple and absorb the spurious signal's energy. All three embodiments absorb negligible energy at the selected frequency and so do not significantly diminish the energy efficiency of the lamp.

Method and apparatus for powering an electrodeless lamp with reduced radio frequency interference

DOEpatents

Simpson, J.E.

1999-06-08

An electrodeless lamp waveguide structure includes tuned absorbers for spurious RF signals. A lamp waveguide with an integral frequency selective attenuation includes resonant absorbers positioned within the waveguide to absorb spurious out-of-band RF energy. The absorbers have a negligible effect on energy at the selected frequency used to excite plasma in the lamp. In a first embodiment, one or more thin slabs of lossy magnetic material are affixed to the sidewalls of the waveguide at approximately one quarter wavelength of the spurious signal from an end wall of the waveguide. The positioning of the lossy material optimizes absorption of power from the spurious signal. In a second embodiment, one or more thin slabs of lossy magnetic material are used in conjunction with band rejection waveguide filter elements. In a third embodiment, one or more microstrip filter elements are tuned to the frequency of the spurious signal and positioned within the waveguide to couple and absorb the spurious signal's energy. All three embodiments absorb negligible energy at the selected frequency and so do not significantly diminish the energy efficiency of the lamp. 18 figs.

Active noise control using noise source having adaptive resonant frequency tuning through stress variation

NASA Technical Reports Server (NTRS)

Pla, Frederic G. (Inventor); Renshaw, Anthony A. (Inventor); Rajiyah, Harindra (Inventor); Hedeen, Robert A. (Inventor)

1995-01-01

A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of a noise radiating element is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating element is tuned by an expandable ring embedded in the noise radiating element. Excitation of the ring causes expansion or contraction of the ring, thereby varying the stress in the noise radiating element. The ring is actuated by a controller which receives input of a feedback signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the ring, causing the ring to expand or contract. Instead of a single ring embedded in the noise radiating panel, a first expandable ring can be bonded to one side of the noise radiating element, and a second expandable ring can be bonded to the other side.

A monolithic integrated photonic microwave filter

NASA Astrophysics Data System (ADS)

Fandiño, Javier S.; Muñoz, Pascual; Doménech, David; Capmany, José

2017-02-01

Meeting the increasing demand for capacity in wireless networks requires the harnessing of higher regions in the radiofrequency spectrum, reducing cell size, as well as more compact, agile and power-efficient base stations that are capable of smoothly interfacing the radio and fibre segments. Fully functional microwave photonic chips are promising candidates in attempts to meet these goals. In recent years, many integrated microwave photonic chips have been reported in different technologies. To the best of our knowledge, none has monolithically integrated all the main active and passive optoelectronic components. Here, we report the first demonstration of a tunable microwave photonics filter that is monolithically integrated into an indium phosphide chip. The reconfigurable radiofrequency photonic filter includes all the necessary elements (for example, lasers, modulators and photodetectors), and its response can be tuned by means of control electric currents. This is an important step in demonstrating the feasibility of integrated and programmable microwave photonic processors.

An ultra-accurate numerical method in the design of liquid phononic crystals with hard inclusion

NASA Astrophysics Data System (ADS)

Li, Eric; He, Z. C.; Wang, G.; Liu, G. R.

2017-12-01

The phononics crystals (PCs) are periodic man-made composite materials. In this paper, a mass-redistributed finite element method (MR-FEM) is formulated to study the wave propagation within liquid PCs with hard inclusion. With a perfect balance between stiffness and mass in the MR-FEM model, the dispersion error of longitudinal wave is minimized by redistribution of mass. Such tuning can be easily achieved by adjusting the parameter r that controls the location of integration points of mass matrix. More importantly, the property of mass conservation in the MR-FEM model indicates that the locations of integration points inside or outside the element are immaterial. Four numerical examples are studied in this work, including liquid PCs with cross and circle hard inclusions, different size of inclusion and defect. Compared with standard finite element method, the numerical results have verified the accuracy and effectiveness of MR-FEM. The proposed MR-FEM is a unique and innovative numerical approach with its outstanding features, which has strong potentials to study the stress wave within multi-physics PCs.

Demonstration of a wireless, self-powered, electroacoustic liner system.

PubMed

Phipps, Alex; Liu, Fei; Cattafesta, Louis; Sheplak, Mark; Nishida, Toshikazu

2009-02-01

This paper demonstrates the system operation of a self-powered active liner for the suppression of aircraft engine noise. The fundamental element of the active liner system is an electromechanical Helmholtz resonator (EMHR), which consists of a Helmholtz resonator with one of its rigid walls replaced with a circular piezoceramic composite plate. For this system demonstration, two EMHR elements are used, one for acoustic impedance tuning and one for energy harvesting. The EMHR used for acoustic impedance tuning is shunted with a variable resistive load, while the EMHR used for energy harvesting is shunted to a flyback power converter and storage element. The desired acoustic impedance conditions are determined externally, and wirelessly transmitted to the liner system. The power for the receiver and the impedance tuning circuitry in the liner are supplied by the harvested energy. Tuning of the active liner is demonstrated at three different sound pressure levels (148, 151, and 153 dB) in order to show the robustness of the energy harvesting and storage system. An acoustic tuning range of approximately 200 Hz is demonstrated for each of the three available power levels.

Dynamic response characteristics of dual flow-path integrally bladed rotors

NASA Astrophysics Data System (ADS)

Beck, Joseph A.; Brown, Jeffrey M.; Scott-Emuakpor, Onome E.; Cross, Charles J.; Slater, Joseph C.

2015-02-01

New turbine engine designs requiring secondary flow compression often look to dual flow-path integrally bladed rotors (DFIBRs) since these stages have the ability to perform work on the secondary, or bypassed, flow-field. While analogous to traditional integrally bladed rotor stages, DFIBR designs have many differences that result in unique dynamic response characteristics that must be understood to avoid fatigue. This work investigates these characteristics using reduced-order models (ROMs) that incorporate mistuning through perturbations to blade frequencies. This work provides an alternative to computationally intensive geometric-mistuning approaches for DFIBRs by utilizing tuned blade mode reductions and substructure coupling in cyclic coordinates. Free and forced response results are compared to full finite element model (FEM) solutions to determine if any errors are related to the reduced-order model formulation reduction methods. It is shown that DFIBRs have many more frequency veering regions than their single flow-path integrally blade rotor (IBR) counterparts. Modal families are shown to transition between system, inner-blade, and outer-blade motion. Furthermore, findings illustrate that while mode localization of traditional IBRs is limited to a single or small subset of blades, DFIBRs can have modal energy localized to either an inner- or outer-blade set resulting in many blades responding above tuned levels. Lastly, ROM forced response predictions compare well to full FEM predictions for the two test cases shown.

The Metals in the Biological Periodic System of the Elements: Concepts and Conjectures

PubMed Central

Maret, Wolfgang

2016-01-01

A significant number of chemical elements are either essential for life with known functions, or present in organisms with poorly defined functional outcomes. We do not know all the essential elements with certainty and we know even less about the functions of apparently non-essential elements. In this article, I discuss a basis for a biological periodic system of the elements and that biochemistry should include the elements that are traditionally part of inorganic chemistry and not only those that are in the purview of organic chemistry. A biological periodic system of the elements needs to specify what “essential” means and to which biological species it refers. It represents a snapshot of our present knowledge and is expected to undergo further modifications in the future. An integrated approach of biometal sciences called metallomics is required to understand the interactions of metal ions, the biological functions that their chemical structures acquire in the biological system, and how their usage is fine-tuned in biological species and in populations of species with genetic variations (the variome). PMID:26742035

Differential Resonant Ring YIG Tuned Oscillator

NASA Technical Reports Server (NTRS)

Parrott, Ronald A.

2010-01-01

A differential SiGe oscillator circuit uses a resonant ring-oscillator topology in order to electronically tune the oscillator over multi-octave bandwidths. The oscillator s tuning is extremely linear, because the oscillator s frequency depends on the magnetic tuning of a YIG sphere, whose resonant frequency is equal to a fundamental constant times the DC magnetic field. This extremely simple circuit topology uses two coupling loops connecting a differential pair of SiGe bipolar transistors into a feedback configuration using a YIG tuned filter creating a closed-loop ring oscillator. SiGe device technology is used for this oscillator in order to keep the transistor s 1/f noise to an absolute minimum in order to achieve minimum RF phase noise. The single-end resonant ring oscillator currently has an advantage in fewer parts, but when the oscillation frequency is greater than 16 GHz, the package s parasitic behavior couples energy to the sphere and causes holes and poor phase noise performance. This is because the coupling to the YIG is extremely low, so that the oscillator operates at near the unloaded Q. With the differential resonant ring oscillator, the oscillation currents are just in the YIG coupling mechanisms. The phase noise is even better, and the physical size can be reduced to permit monolithic microwave integrated circuit oscillators. This invention is a YIG tuned oscillator circuit making use of a differential topology to simultaneously achieve an extremely broadband electronic tuning range and ultra-low phase noise. As a natural result of its differential circuit topology, all reactive elements, such as tuning stubs, which limit tuning bandwidth by contributing excessive open loop phase shift, have been eliminated. The differential oscillator s open-loop phase shift is associated with completely non-dispersive circuit elements such as the physical angle of the coupling loops, a differential loop crossover, and the high-frequency phase shift of the n-p-n transistors. At the input of the oscillator s feedback loop is a pair of differentially connected n-p-n SiGe transistors that provides extremely high gain, and because they are bulk-effect devices, extremely low 1/f noise (leading to ultralow RF phase noise). The 1/f corner frequency for n-p-n SiGe transistors is approximately 500 Hz. The RF energy from the transistor s collector output is connected directly to the top-coupling loop (the excitation loop) of a single-sphere YIG tuned filter. A uniform magnetic field to bias the YIG must be at a right angle to any vector associated with an RF current in a coupling loop in order for the precession to interact with the RF currents.

Passive and electro-optic polymer photonics and InP electronics integration

NASA Astrophysics Data System (ADS)

Zhang, Z.; Katopodis, V.; Groumas, P.; Konczykowska, A.; Dupuy, J.-.; Beretta, A.; Dede, A.; Miller, E.; Choi, J. H.; Harati, P.; Jorge, F.; Nodjiadjim, V.; Dinu, R.; Cangini, G.; Vannucci, A.; Felipe, D.; Maese-Novo, A.; Keil, N.; Bach, H.-.; Schell, Martin; Avramopoulos, H.; Kouloumentas, Ch.

2015-05-01

Hybrid photonic integration allows individual components to be developed at their best-suited material platforms without sacrificing the overall performance. In the past few years a polymer-enabled hybrid integration platform has been established, comprising 1) EO polymers for constructing low-complexity and low-cost Mach-Zehnder modulators (MZMs) with extremely high modulation bandwidth; 2) InP components for light sources, detectors, and high-speed electronics including MUX drivers and DEMUX circuits; 3) Ceramic (AIN) RF board that links the electronic signals within the package. On this platform, advanced optoelectronic modules have been demonstrated, including serial 100 Gb/s [1] and 2x100 Gb/s [2] optical transmitters, but also 400 Gb/s optoelectronic interfaces for intra-data center networks [3]. To expand the device functionalities to an unprecedented level and at the same time improve the integration compatibility with diversified active / passive photonic components, we have added a passive polymer-based photonic board (polyboard) as the 4th material system. This passive polyboard allows for low-cost fabrication of single-mode waveguide networks, enables fast and convenient integration of various thin-film elements (TFEs) to control the light polarization, and provides efficient thermo-optic elements (TOEs) for wavelength tuning, light amplitude regulation and light-path switching.

Optical harmonic generator

DOEpatents

Summers, M.A.; Eimerl, D.; Boyd, R.D.

1982-06-10

A pair of uniaxial birefringent crystal elements are fixed together to form a serially arranged, integral assembly which, alternatively, provides either a linearly or elliptically polarized second-harmonic output wave or a linearly polarized third-harmonic output wave. The extraordinary or e directions of the crystal elements are oriented in the integral assembly to be in quadrature (90/sup 0/). For a second-harmonic generation in the Type-II-Type-II angle tuned case, the input fundamental wave has equal amplitude o and e components. For a third-harmonic generation, the input fundamental wave has o and e components whose amplitudes are in a ratio of 2:1 (o:e reference first crystal). In the typical case of a linearly polarized input fundamental wave this can be accomplished by simply rotating the crystal assembly about the input beam direction by 10/sup 0/. For both second and third harmonic generation input precise phase-matching is achieved by tilting the crystal assembly about its two sensitive axeses (o).

Optical harmonic generator

DOEpatents

Summers, Mark A.; Eimerl, David; Boyd, Robert D.

1985-01-01

A pair of uniaxial birefringent crystal elements are fixed together to form a serially arranged, integral assembly which, alternatively, provides either a linearly or elliptically polarized second-harmonic output wave or a linearly polarized third-harmonic output wave. The "extraordinary" or "e" directions of the crystal elements are oriented in the integral assembly to be in quadrature (90.degree.). For a second-harmonic generation in the Type-II-Type-II angle tuned case, the input fundamental wave has equal amplitude "o" and "e" components. For a third-harmonic generation, the input fundamental wave has "o" and "e" components whose amplitudes are in a ratio of 2:1 ("o":"e" reference first crystal). In the typical case of a linearly polarized input fundamental wave this can be accomplished by simply rotating the crystal assembly about the input beam direction by 10.degree.. For both second and third harmonic generation input precise phase-matching is achieved by tilting the crystal assembly about its two sensitive axes ("o").

Design and Development of Wireless Power Transmission for Unmanned Air Vehicles

DTIC Science & Technology

2012-09-01

ELECTRONIC WARFARE SYSTEMS ENGINEERING and MASTER OF SCIENCE IN ELECTRICAL ENGINEERING from the NAVAL POSTGRADUATE SCHOOL September 2012...Agilent Advanced Design System (ADS). Tuning elements were added and adjusted in order to optimize the efficiency. A maximum efficiency of 57% was...investigated by a series of simulations using Agilent Advanced Design System (ADS). Tuning elements were added and adjusted

Core element characterization of Rhodococcus promoters and development of a promoter-RBS mini-pool with different activity levels for efficient gene expression.

PubMed

Jiao, Song; Yu, Huimin; Shen, Zhongyao

2018-09-25

To satisfy the urgent demand for promoter engineering that can accurately regulate the metabolic circuits and expression of specific genes in the Rhodococcus microbial platform, a promoter-ribosome binding site (RBS) coupled mini-pool with fine-tuning of different activity levels was successfully established. Transcriptome analyses of R. ruber TH revealed several representative promoters with different activity levels, e.g., Pami, Pcs, Pnh, P50sl36, PcbiM, PgroE and Pniami. β-Galactosidase (LacZ) reporter measurement demonstrated that different gene expression levels could be obtained with these natural promoters combined with an optimal RBS of ami. Further use of these promoters to overexpress the nitrile hydratase (NHase) gene with RBSami in R. ruber THdAdN produced different expression levels consistent with the transcription analyses. The -35 and -10 core elements of different promoters were further analyzed, and the conserved sequences were revealed to be TTGNNN and (T/C)GNNA(A/C)AAT. By mutating the core elements of the strong promoters, Pnh and Pami, into the above consensus sequence, two even stronger promoters, PnhM and PamiM, were obtained with 2.2-fold and 7.7-fold improvements in transcription, respectively. Integrating several strategies, including transcriptome promoter screening, -35 and -10 core element identification, core element point-mutation, RBS optimization and diverse reporter verification, a fine-tuning promoter-RBS combination mini-pool with different activity levels in Rhodococcus strains was successfully established. This development is significant for broad applications of the Rhodococcus genus as a microbial platform. Copyright © 2018 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lentine, Anthony L.; Kekatpure, Rohan Deodatta; Zortman, William A.

A photonic resonator system is designed to use thermal tuning to adjust the resonant wavelength of each resonator in the system, with a separate tuning circuit associated with each resonator so that individual adjustments may be made. The common electrical ground connection between the tuning circuits is particularly formed to provide thermal isolation between adjacent resonators by including a capacitor along each return path to ground, where the presence of the capacitor's dielectric material provides the thermal isolation. The use of capacitively coupling necessarily requires the use of an AC current as an input to the heater element (conductor/resistor) ofmore » each resonator, where the RMS value of the AC signal is indicative of the amount of heat that is generated along the element and the degree of wavelength tuning that is obtained.« less

Broadband microwave photonic fully tunable filter using a single heterogeneously integrated III-V/SOI-microdisk-based phase shifter.

PubMed

Lloret, Juan; Morthier, Geert; Ramos, Francisco; Sales, Salvador; Van Thourhout, Dries; Spuesens, Thijs; Olivier, Nicolas; Fédéli, Jean-Marc; Capmany, José

2012-05-07

A broadband microwave photonic phase shifter based on a single III-V microdisk resonator heterogeneously integrated on and coupled to a nanophotonic silicon-on-insulator waveguide is reported. The phase shift tunability is accomplished by modifying the effective index through carrier injection. A comprehensive semi-analytical model aiming at predicting its behavior is formulated and confirmed by measurements. Quasi-linear and continuously tunable 2π phase shifts at radiofrequencies greater than 18 GHz are experimentally demonstrated. The phase shifter performance is also evaluated when used as a key element in tunable filtering schemes. Distortion-free and wideband filtering responses with a tuning range of ~100% over the free spectral range are obtained.

Grid cell spatial tuning reduced following systemic muscarinic receptor blockade

PubMed Central

Newman, Ehren L.; Climer, Jason R.; Hasselmo, Michael E.

2014-01-01

Grid cells of the medial entorhinal cortex exhibit a periodic and stable pattern of spatial tuning that may reflect the output of a path integration system. This grid pattern has been hypothesized to serve as a spatial coordinate system for navigation and memory function. The mechanisms underlying the generation of this characteristic tuning pattern remain poorly understood. Systemic administration of the muscarinic antagonist scopolamine flattens the typically positive correlation between running speed and entorhinal theta frequency in rats. The loss of this neural correlate of velocity, an important signal for the calculation of path integration, raises the question of what influence scopolamine has on the grid cell tuning as a read out of the path integration system. To test this, the spatial tuning properties of grid cells were compared before and after systemic administration of scopolamine as rats completed laps on a circle track for food rewards. The results show that the spatial tuning of the grid cells was reduced following scopolamine administration. The tuning of head direction cells, in contrast, was not reduced by scopolamine. This is the first report to demonstrate a link between cholinergic function and grid cell tuning. This work suggests that the loss of tuning in the grid cell network may underlie the navigational disorientation observed in Alzheimer's patients and elderly individuals with reduced cholinergic tone. PMID:24493379

Fine tuning of transmission features in nanoporous anodic alumina distributed Bragg reflectors

NASA Astrophysics Data System (ADS)

Lim, Siew Yee; Law, Cheryl Suwen; Santos, Abel

2018-01-01

This study introduces an innovative apodisation strategy to tune the filtering features of distributed Bragg reflectors based on nanoporous anodic alumina (NAA-DBRs). The effective medium of NAA-DBRs, which is modulated in a stepwise fashion by a pulse-like anodisation approach, is apodised following a logarithmic negative function to engineer the transmission features of NAA-DBRs. We investigate the effect of various apodisation parameters such as apodisation amplitude difference, anodisation period, current density offset and pore widening time, to tune and optimise the optical properties of NAA-DBRs in terms of central wavelength position, full width at half maximum and quality of photonic stop band. The transmission features of NAA-DBRs are shown to be fully controllable with precision across the spectral regions by means of the apodisation parameters. Our study demonstrates that an apodisation strategy can significantly narrow the width and enhance the quality of the characteristic photonic stop band of NAA-DBRs. This rationally designed anodisation approach based on the combination of apodisation and stepwise pulse anodisation enables the development of optical filters with tuneable filtering features to be integrated into optical technologies acting as essential photonic elements in devices such as optical sensors and biosensors.

Mechanically tunable terahertz graphene plasmonics using soft metasurface

NASA Astrophysics Data System (ADS)

Wang, Li; Liu, Xin; Zang, Jianfeng

2016-12-01

This letter presents a new approach to continuously tune the resonances of graphene plasmons in terahertz soft metasurface. The continuous tunability of plasmon resonance is either unachievable in conventional plasmonic materials like noble metals or requires gate voltage regulation in graphene. Here we investigate a simplest form of terahertz metasurface, graphene nanoribbon arrays (GNRAs), and demonstrate the graphene plasmon resonance modes can be tailored by mechanical deformation of the elastomeric substrate using finite element method (FEM). By integrating the electric doping with substrate deformation, we have managed to tune the resonance wavelength from 13.7 to 50.6 μm. The 36.9 μm tuning range is nearly doubled compared with that by electric doping regulation only. Moreover, we observe the plasmon coupling effect in GNRAs on waved substrate and its evolution with substrate curvature. A new decoupling mechanism enabled by the out-of-plane separation of the adjacent ribbons is revealed. The out-of-plane setup of plasmonic components extends the fabrication of plasmonic devices into three-dimensional space, which simultaneously increases the nanoribbon density and decreases the coupling strength. Our findings provide an additional degree of freedom to design reconfigurable metasurfaces and metadevices.

Tunable electromagnetically induced transparency in integrated silicon photonics circuit.

PubMed

Li, Ang; Bogaerts, Wim

2017-12-11

We comprehensively simulate and experimentally demonstrate a novel approach to generate tunable electromagnetically induced transparency (EIT) in a fully integrated silicon photonics circuit. It can also generate tunable fast and slow light. The circuit is a single ring resonator with two integrated tunable reflectors inside, which form an embedded Fabry-Perot (FP) cavity inside the ring cavity. The mode of the FP cavity can be controlled by tuning the reflections using integrated thermo-optic tuners. Under correct tuning conditions, the interaction of the FP mode and the ring resonance mode will generate a Fano resonance and an EIT response. The extinction ratio and bandwidth of the EIT can be tuned by controlling the reflectors. Measured group delay proves that both fast light and slow light can be generated under different tuning conditions. A maximum group delay of 1100 ps is observed because of EIT. Pulse advance around 1200 ps is also demonstrated.

A Low Temperature Co-fired Ceramics Manufactured Power Inductor Based on A Ternary Hybrid Material System

NASA Astrophysics Data System (ADS)

Xie, Yunsong; Chen, Ru

Low temperature co-fired ceramics (LTCC) is one of the most important techniques to produce circuits with high working frequency, multi-functionality and high integration. We have developed a methodology to enable a ternary hybrid material system being implemented into the LTCC manufacturing process. The co-firing sintering process can be divided into a densification and cooling process. In this method, a successful ternary hybrid material densification process is achieved by tuning the sintering profile of each material to match each other. The system integrity is maintained in the cooling process is obtained by develop a strong bonding at the interfaces of each materials. As a demonstration, we have construct a power inductor device made of the ternary material system including Ag, NiCuZn ferrite and non-magnetic ceramic. The power inductors well maintains its physical integrity after sintering. The microscopic images show no obvious sign of cracks or structural deformation. More importantly, despite the bonding between the ferrite and ceramic is enhanced by non-magnetic element diffusion, the undesired magnetic elements diffusion is effectively suppressed. The electric performance shows that the power handling capability is comparable to the current state of art device.

Method for fabrication and verification of conjugated nanoparticle-antibody tuning elements for multiplexed electrochemical biosensors.

PubMed

La Belle, Jeffrey T; Fairchild, Aaron; Demirok, Ugur K; Verma, Aman

2013-05-15

There is a critical need for more accurate, highly sensitive and specific assay for disease diagnosis and management. A novel, multiplexed, single sensor using rapid and label free electrochemical impedance spectroscopy tuning method has been developed. The key challenges while monitoring multiple targets is frequency overlap. Here we describe the methods to circumvent the overlap, tune by use of nanoparticle (NP) and discuss the various fabrication and characterization methods to develop this technique. First sensors were fabricated using printed circuit board (PCB) technology and nickel and gold layers were electrodeposited onto the PCB sensors. An off-chip conjugation of gold NP's to molecular recognition elements (with verification technique) is described as well. A standard covalent immobilization of the molecular recognition elements is also discussed with quality control techniques. Finally use and verification of sensitivity and specificity is also presented. By use of gold NP's of various sizes, we have demonstrated the possibility and shown little loss of sensitivity and specificity in the molecular recognition of inflammatory markers as "model" targets for our tuning system. By selection of other sized NP's or NP's of various materials, the tuning effect can be further exploited. The novel platform technology developed could be utilized in critical care, clinical management and at home health and disease management. Copyright © 2013 Elsevier Inc. All rights reserved.

A single active nanoelectromechanical tuning fork front-end radio-frequency receiver

NASA Astrophysics Data System (ADS)

Bartsch, Sebastian T.; Rusu, A.; Ionescu, Adrian M.

2012-06-01

Nanoelectromechanical systems (NEMS) offer the potential to revolutionize fundamental methods employed for signal processing in today’s telecommunication systems, owing to their spectral purity and the prospect of integration with existing technology. In this work we present a novel, front-end receiver topology based on a single device silicon nanoelectromechanical mixer-filter. The operation is demonstrated by using the signal amplification in a field effect transistor (FET) merged into a tuning fork resonator. The combination of both a transistor and a mechanical element into a hybrid unit enables on-chip functionality and performance previously unachievable in silicon. Signal mixing, filtering and demodulation are experimentally demonstrated at very high frequencies ( > 100 MHz), maintaining a high quality factor of Q = 800 and stable operation at near ambient pressure (0.1 atm) and room temperature (T = 300 K). The results show that, ultimately miniaturized, silicon NEMS can be utilized to realize multi-band, single-chip receiver systems based on NEMS mixer-filter arrays with reduced system complexity and power consumption.

A frequency and sensitivity tunable microresonator array for high-speed quantum processor readout

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whittaker, J. D., E-mail: jwhittaker@dwavesys.com; Swenson, L. J.; Volkmann, M. H.

Superconducting microresonators have been successfully utilized as detection elements for a wide variety of applications. With multiplexing factors exceeding 1000 detectors per transmission line, they are the most scalable low-temperature detector technology demonstrated to date. For high-throughput applications, fewer detectors can be coupled to a single wire but utilize a larger per-detector bandwidth. For all existing designs, fluctuations in fabrication tolerances result in a non-uniform shift in resonance frequency and sensitivity, which ultimately limits the efficiency of bandwidth utilization. Here, we present the design, implementation, and initial characterization of a superconducting microresonator readout integrating two tunable inductances per detector. Wemore » demonstrate that these tuning elements provide independent control of both the detector frequency and sensitivity, allowing us to maximize the transmission line bandwidth utilization. Finally, we discuss the integration of these detectors in a multilayer fabrication stack for high-speed readout of the D-Wave quantum processor, highlighting the use of control and routing circuitry composed of single-flux-quantum loops to minimize the number of control wires at the lowest temperature stage.« less

Two-dimensional beam steering using a thermo-optic silicon photonic optical phased array

NASA Astrophysics Data System (ADS)

Rabinovich, William S.; Goetz, Peter G.; Pruessner, Marcel W.; Mahon, Rita; Ferraro, Mike S.; Park, Doe; Fleet, Erin; DePrenger, Michael J.

2016-11-01

Many components for free-space optical (FSO) communication systems have shrunken in size over the last decade. However, the steering systems have remained large and power hungry. Nonmechanical beam steering offers a path to reducing the size of these systems. Optical phased arrays can allow integrated beam steering elements. One of the most important aspects of an optical phased array technology is its scalability to a large number of elements. Silicon photonics can potentially offer this scalability using CMOS foundry techniques. A phased array that can steer in two dimensions using the thermo-optic effect is demonstrated. No wavelength tuning of the input laser is needed and the design allows a simple control system with only two inputs. A benchtop FSO link with the phased array in both transmit and receive mode is demonstrated.

Adaptive critic autopilot design of bank-to-turn missiles using fuzzy basis function networks.

PubMed

Lin, Chuan-Kai

2005-04-01

A new adaptive critic autopilot design for bank-to-turn missiles is presented. In this paper, the architecture of adaptive critic learning scheme contains a fuzzy-basis-function-network based associative search element (ASE), which is employed to approximate nonlinear and complex functions of bank-to-turn missiles, and an adaptive critic element (ACE) generating the reinforcement signal to tune the associative search element. In the design of the adaptive critic autopilot, the control law receives signals from a fixed gain controller, an ASE and an adaptive robust element, which can eliminate approximation errors and disturbances. Traditional adaptive critic reinforcement learning is the problem faced by an agent that must learn behavior through trial-and-error interactions with a dynamic environment, however, the proposed tuning algorithm can significantly shorten the learning time by online tuning all parameters of fuzzy basis functions and weights of ASE and ACE. Moreover, the weight updating law derived from the Lyapunov stability theory is capable of guaranteeing both tracking performance and stability. Computer simulation results confirm the effectiveness of the proposed adaptive critic autopilot.

Discrete tuning concept for fiber-integrated lasers based on tailored FBG arrays and a theta cavity layout.

PubMed

Tiess, Tobias; Becker, Martin; Rothhardt, Manfred; Bartelt, Hartmut; Jäger, Matthias

2017-03-15

We demonstrate a novel tuning concept for pulsed fiber-integrated lasers with a fiber Bragg grating (FBG) array as a discrete and tailored spectral filter, as well as a modified laser design. Based on a theta cavity layout, the structural delay lines originating from the FBG array are balanced, enabling a constant repetition rate and stable pulse properties over the full tuning range. The emission wavelength is electrically tuned with respect to the filter properties based on an adapted temporal gating scheme using an acousto-optic modulator. This concept has been investigated with an Yb-doped fiber laser, demonstrating excellent emission properties with high signal contrast (>35  dB) and narrow linewidth (<150  pm) over a tuning range of 25 nm.

Cognitive programs: software for attention's executive

PubMed Central

Tsotsos, John K.; Kruijne, Wouter

2014-01-01

What are the computational tasks that an executive controller for visual attention must solve? This question is posed in the context of the Selective Tuning model of attention. The range of required computations go beyond top-down bias signals or region-of-interest determinations, and must deal with overt and covert fixations, process timing and synchronization, information routing, memory, matching control to task, spatial localization, priming, and coordination of bottom-up with top-down information. During task execution, results must be monitored to ensure the expected results. This description includes the kinds of elements that are common in the control of any kind of complex machine or system. We seek a mechanistic integration of the above, in other words, algorithms that accomplish control. Such algorithms operate on representations, transforming a representation of one kind into another, which then forms the input to yet another algorithm. Cognitive Programs (CPs) are hypothesized to capture exactly such representational transformations via stepwise sequences of operations. CPs, an updated and modernized offspring of Ullman's Visual Routines, impose an algorithmic structure to the set of attentional functions and play a role in the overall shaping of attentional modulation of the visual system so that it provides its best performance. This requires that we consider the visual system as a dynamic, yet general-purpose processor tuned to the task and input of the moment. This differs dramatically from the almost universal cognitive and computational views, which regard vision as a passively observing module to which simple questions about percepts can be posed, regardless of task. Differing from Visual Routines, CPs explicitly involve the critical elements of Visual Task Executive (vTE), Visual Attention Executive (vAE), and Visual Working Memory (vWM). Cognitive Programs provide the software that directs the actions of the Selective Tuning model of visual attention. PMID:25505430

Finite Element-Based Mechanical Assessment of Bone Quality on the Basis of In Vivo Images.

PubMed

Pahr, Dieter H; Zysset, Philippe K

2016-12-01

Beyond bone mineral density (BMD), bone quality designates the mechanical integrity of bone tissue. In vivo images based on X-ray attenuation, such as CT reconstructions, provide size, shape, and local BMD distribution and may be exploited as input for finite element analysis (FEA) to assess bone fragility. Further key input parameters of FEA are the material properties of bone tissue. This review discusses the main determinants of bone mechanical properties and emphasizes the added value, as well as the important assumptions underlying finite element analysis. Bone tissue is a sophisticated, multiscale composite material that undergoes remodeling but exhibits a rather narrow band of tissue mineralization. Mechanically, bone tissue behaves elastically under physiologic loads and yields by cracking beyond critical strain levels. Through adequate cell-orchestrated modeling, trabecular bone tunes its mechanical properties by volume fraction and fabric. With proper calibration, these mechanical properties may be incorporated in quantitative CT-based finite element analysis that has been validated extensively with ex vivo experiments and has been applied increasingly in clinical trials to assess treatment efficacy against osteoporosis.

Nearly ferromagnetic Fermi-liquid behaviour in YFe2Zn20 and high-temperature ferromagnetism of GdFe2Zn20

NASA Astrophysics Data System (ADS)

Jia, S.; Bud'Ko, S. L.; Samolyuk, G. D.; Canfield, P. C.

2007-05-01

One of the historic goals of alchemy was to turn base elements into precious ones. Although the practice of alchemy has been superseded by chemistry and solid-state physics, the desire to dramatically change or tune the properties of a compound, preferably through small changes in stoichiometry or composition, remains. This desire becomes even more compelling for compounds that can be tuned to extremes in behaviour. Here, we report that the RT2Zn20 (R=rare earth and T=transition metal) family of compounds manifests exactly this type of versatility, even though they are more than 85% Zn. By tuning T, we find that YFe2Zn20 is closer to ferromagnetism than elemental Pd, the classic example of a nearly ferromagnetic Fermi liquid. By submerging Gd in this highly polarizable Fermi liquid, we tune the system to a remarkably high-temperature ferromagnetic (TC=86K) state for a compound with less than 5% Gd. Although this is not quite turning lead into gold, it is essentially tuning Zn to become a variety of model compounds.

FLUIDIC AC AMPLIFIERS.

DTIC Science & Technology

Several fluidic tuned AC Amplifiers were designed and tested. Interstage tuning and feedback designs are considered. Good results were obtained...corresponding Q’s as high as 12. Element designs and test results of one, two, and three stage amplifiers are presented. AC Modulated Carrier Systems

Efficient techniques for forced response involving linear modal components interconnected by discrete nonlinear connection elements

NASA Astrophysics Data System (ADS)

Avitabile, Peter; O'Callahan, John

2009-01-01

Generally, response analysis of systems containing discrete nonlinear connection elements such as typical mounting connections require the physical finite element system matrices to be used in a direct integration algorithm to compute the nonlinear response analysis solution. Due to the large size of these physical matrices, forced nonlinear response analysis requires significant computational resources. Usually, the individual components of the system are analyzed and tested as separate components and their individual behavior may essentially be linear when compared to the total assembled system. However, the joining of these linear subsystems using highly nonlinear connection elements causes the entire system to become nonlinear. It would be advantageous if these linear modal subsystems could be utilized in the forced nonlinear response analysis since much effort has usually been expended in fine tuning and adjusting the analytical models to reflect the tested subsystem configuration. Several more efficient techniques have been developed to address this class of problem. Three of these techniques given as: equivalent reduced model technique (ERMT);modal modification response technique (MMRT); andcomponent element method (CEM); are presented in this paper and are compared to traditional methods.

Web party effect: a cocktail party effect in the web environment

PubMed Central

Gerbino, Walter

2015-01-01

In goal-directed web navigation, labels compete for selection: this process often involves knowledge integration and requires selective attention to manage the dizziness of web layouts. Here we ask whether the competition for selection depends on all web navigation options or only on those options that are more likely to be useful for information seeking, and provide evidence in favor of the latter alternative. Participants in our experiment navigated a representative set of real websites of variable complexity, in order to reach an information goal located two clicks away from the starting home page. The time needed to reach the goal was accounted for by a novel measure of home page complexity based on a part of (not all) web options: the number of links embedded within web navigation elements weighted by the number and type of embedding elements. Our measure fully mediated the effect of several standard complexity metrics (the overall number of links, words, images, graphical regions, the JPEG file size of home page screenshots) on information seeking time and usability ratings. Furthermore, it predicted the cognitive demand of web navigation, as revealed by the duration judgment ratio (i.e., the ratio of subjective to objective duration of information search). Results demonstrate that focusing on relevant links while ignoring other web objects optimizes the deployment of attentional resources necessary to navigation. This is in line with a web party effect (i.e., a cocktail party effect in the web environment): users tune into web elements that are relevant for the achievement of their navigation goals and tune out all others. PMID:25802803

Web party effect: a cocktail party effect in the web environment.

PubMed

Rigutti, Sara; Fantoni, Carlo; Gerbino, Walter

2015-01-01

In goal-directed web navigation, labels compete for selection: this process often involves knowledge integration and requires selective attention to manage the dizziness of web layouts. Here we ask whether the competition for selection depends on all web navigation options or only on those options that are more likely to be useful for information seeking, and provide evidence in favor of the latter alternative. Participants in our experiment navigated a representative set of real websites of variable complexity, in order to reach an information goal located two clicks away from the starting home page. The time needed to reach the goal was accounted for by a novel measure of home page complexity based on a part of (not all) web options: the number of links embedded within web navigation elements weighted by the number and type of embedding elements. Our measure fully mediated the effect of several standard complexity metrics (the overall number of links, words, images, graphical regions, the JPEG file size of home page screenshots) on information seeking time and usability ratings. Furthermore, it predicted the cognitive demand of web navigation, as revealed by the duration judgment ratio (i.e., the ratio of subjective to objective duration of information search). Results demonstrate that focusing on relevant links while ignoring other web objects optimizes the deployment of attentional resources necessary to navigation. This is in line with a web party effect (i.e., a cocktail party effect in the web environment): users tune into web elements that are relevant for the achievement of their navigation goals and tune out all others.

On-Chip Microwave Quantum Hall Circulator

NASA Astrophysics Data System (ADS)

Mahoney, A. C.; Colless, J. I.; Pauka, S. J.; Hornibrook, J. M.; Watson, J. D.; Gardner, G. C.; Manfra, M. J.; Doherty, A. C.; Reilly, D. J.

2017-01-01

Circulators are nonreciprocal circuit elements that are integral to technologies including radar systems, microwave communication transceivers, and the readout of quantum information devices. Their nonreciprocity arises from the interference of microwaves over the centimeter scale of the signal wavelength, in the presence of bulky magnetic media that breaks time-reversal symmetry. Here, we realize a completely passive on-chip microwave circulator with size 1 /1000 th the wavelength by exploiting the chiral, "slow-light" response of a two-dimensional electron gas in the quantum Hall regime. For an integrated GaAs device with 330 μ m diameter and about 1-GHz center frequency, a nonreciprocity of 25 dB is observed over a 50-MHz bandwidth. Furthermore, the nonreciprocity can be dynamically tuned by varying the voltage at the port, an aspect that may enable reconfigurable passive routing of microwave signals on chip.

Lithographic fine-tuning of vertical cavity surface emitting laser-pumped two-dimensional photonic crystal lasers.

PubMed

Cao, J R; Lee, Po-Tsung; Choi, Sang-Jun; O'Brien, John D; Dapkus, P Daniel

2002-01-01

Lithographic tuning of operating wavelengths in a photonic crystal laser array is demonstrated. The photonic crystal lattice constant is varied by 2 nm between elements of the array, and a wavelength spacing of approximately 4 nm is achieved.

Recent developments using TowerJazz SiGe BiCMOS platform for mmWave and THz applications

NASA Astrophysics Data System (ADS)

Kar-Roy, Arjun; Howard, David; Preisler, Edward J.; Racanelli, Marco

2013-05-01

In this paper, we report on the highest speed 240GHz/340GHz FT/FMAX NPN which is now available for product designs in the SBC18H4 process variant of TowerJazz's mature 0.18μm SBC18 silicon germanium (SiGe) BiCMOS technology platform. NFMIN of ~2dB at 50GHz has been obtained with these NPNs. We also describe the integration of earlier generation NPNs with FT/FMAX of 240GHz/280GHz into SBC13H3, a 0.13μm SiGe BiCMOS technology platform. Next, we detail the integration of the deep silicon via (DSV), through silicon via (TSV), high-resistivity substrate, sub-field stitching and hybrid-stitching capability into the 0.18μm SBC18 technology platform to enable higher performance and highly integrated product designs. The integration of SBC18H3 into a thick-film SOI substrate, with essentially unchanged FT and FMAX, is also described. We also report on recent circuit demonstrations using the SBC18H3 platform: (1) a 4-element phased-array 70-100GHz broadband transmit and receive chip with flat saturated power greater than 5dBm and conversion gain of 33dB; (2) a fully integrated W-band 9-element phase-controllable array with responsivity of 800MV/W and receiver NETD is 0.45K with 20ms integration time; (3) a 16-element 4x4 phased-array transmitter with scanning in both the E- and H-planes with maximum EIRP of 23-25 dBm at 100-110GHz; (4) a power efficient 200GHz VCO with -7.25dBm output power and tuning range of 3.5%; and (5) a 320GHz 16-element imaging receiver array with responsivity of 18KV/W at 315GHz, a 3dB bandwidth of 25GHz and a low NEP of 34pW/Hz1/2. Wafer-scale large-die implementation of the phased-arrays and mmWave imagers using stitching in TowerJazz SBC18 process are also discussed.

Measuring and Predicting the Internal Structure of Semiconductor Nanocrystals through Raman Spectroscopy.

PubMed

Mukherjee, Prabuddha; Lim, Sung Jun; Wrobel, Tomasz P; Bhargava, Rohit; Smith, Andrew M

2016-08-31

Nanocrystals composed of mixed chemical domains have diverse properties that are driving their integration in next-generation electronics, light sources, and biosensors. However, the precise spatial distribution of elements within these particles is difficult to measure and control, yet profoundly impacts their quality and performance. Here we synthesized a unique series of 42 different quantum dot nanocrystals, composed of two chemical domains (CdS:CdSe), arranged in 7 alloy and (core)shell structural classes. Chemometric analyses of far-field Raman spectra accurately classified their internal structures from their vibrational signatures. These classifications provide direct insight into the elemental arrangement of the alloy as well as an independent prediction of fluorescence quantum yield. This nondestructive, rapid approach can be broadly applied to greatly enhance our capacity to measure, predict and monitor multicomponent nanomaterials for precise tuning of their structures and properties.

Dynamical beam manipulation based on 2-bit digitally-controlled coding metasurface.

PubMed

Huang, Cheng; Sun, Bo; Pan, Wenbo; Cui, Jianhua; Wu, Xiaoyu; Luo, Xiangang

2017-02-08

Recently, a concept of digital metamaterials has been proposed to manipulate field distribution through proper spatial mixtures of digital metamaterial bits. Here, we present a design of 2-bit digitally-controlled coding metasurface that can effectively modulate the scattered electromagnetic wave and realize different far-field beams. Each meta-atom of this metasurface integrates two pin diodes, and by tuning their operating states, the metasurface has four phase responses of 0, π/2, π, and 3π/2, corresponding to four basic digital elements "00", "01", "10", and "11", respectively. By designing the coding sequence of the above digital element array, the reflected beam can be arbitrarily controlled. The proposed 2-bit digital metasurface has been demonstrated to possess capability of achieving beam deflection, multi-beam and beam diffusion, and the dynamical switching of these different scattering patterns is completed by a programmable electric source.

Dynamical beam manipulation based on 2-bit digitally-controlled coding metasurface

PubMed Central

Huang, Cheng; Sun, Bo; Pan, Wenbo; Cui, Jianhua; Wu, Xiaoyu; Luo, Xiangang

2017-01-01

Recently, a concept of digital metamaterials has been proposed to manipulate field distribution through proper spatial mixtures of digital metamaterial bits. Here, we present a design of 2-bit digitally-controlled coding metasurface that can effectively modulate the scattered electromagnetic wave and realize different far-field beams. Each meta-atom of this metasurface integrates two pin diodes, and by tuning their operating states, the metasurface has four phase responses of 0, π/2, π, and 3π/2, corresponding to four basic digital elements “00”, “01”, “10”, and “11”, respectively. By designing the coding sequence of the above digital element array, the reflected beam can be arbitrarily controlled. The proposed 2-bit digital metasurface has been demonstrated to possess capability of achieving beam deflection, multi-beam and beam diffusion, and the dynamical switching of these different scattering patterns is completed by a programmable electric source. PMID:28176870

Fast and wide tuning wavelength-swept source based on dispersion-tuned fiber optical parametric oscillator.

PubMed

Zhou, Yue; Cheung, Kim K Y; Li, Qin; Yang, Sigang; Chui, P C; Wong, Kenneth K Y

2010-07-15

We demonstrate a dispersion-tuned fiber optical parametric oscillator (FOPO)-based swept source with a sweep rate of 40 kHz and a wavelength tuning range of 109 nm around 1550 nm. The cumulative speed exceeds 4,000,000 nm/s. The FOPO is pumped by a sinusoidally modulated pump, which is driven by a clock sweeping linearly from 1 to 1.0006 GHz. A spool of dispersion-compensating fiber is added inside the cavity to perform dispersion tuning. The instantaneous linewidth is 0.8 nm without the use of any wavelength selective element inside the cavity. 1 GHz pulses with pulse width of 150 ps are generated.

Adaptive GSA-based optimal tuning of PI controlled servo systems with reduced process parametric sensitivity, robust stability and controller robustness.

PubMed

Precup, Radu-Emil; David, Radu-Codrut; Petriu, Emil M; Radac, Mircea-Bogdan; Preitl, Stefan

2014-11-01

This paper suggests a new generation of optimal PI controllers for a class of servo systems characterized by saturation and dead zone static nonlinearities and second-order models with an integral component. The objective functions are expressed as the integral of time multiplied by absolute error plus the weighted sum of the integrals of output sensitivity functions of the state sensitivity models with respect to two process parametric variations. The PI controller tuning conditions applied to a simplified linear process model involve a single design parameter specific to the extended symmetrical optimum (ESO) method which offers the desired tradeoff to several control system performance indices. An original back-calculation and tracking anti-windup scheme is proposed in order to prevent the integrator wind-up and to compensate for the dead zone nonlinearity of the process. The minimization of the objective functions is carried out in the framework of optimization problems with inequality constraints which guarantee the robust stability with respect to the process parametric variations and the controller robustness. An adaptive gravitational search algorithm (GSA) solves the optimization problems focused on the optimal tuning of the design parameter specific to the ESO method and of the anti-windup tracking gain. A tuning method for PI controllers is proposed as an efficient approach to the design of resilient control systems. The tuning method and the PI controllers are experimentally validated by the adaptive GSA-based tuning of PI controllers for the angular position control of a laboratory servo system.

A strong electro-optically active lead-free ferroelectric integrated on silicon

NASA Astrophysics Data System (ADS)

Abel, Stefan; Stöferle, Thilo; Marchiori, Chiara; Rossel, Christophe; Rossell, Marta D.; Erni, Rolf; Caimi, Daniele; Sousa, Marilyne; Chelnokov, Alexei; Offrein, Bert J.; Fompeyrine, Jean

2013-04-01

The development of silicon photonics could greatly benefit from the linear electro-optical properties, absent in bulk silicon, of ferroelectric oxides, as a novel way to seamlessly connect the electrical and optical domain. Of all oxides, barium titanate exhibits one of the largest linear electro-optical coefficients, which has however not yet been explored for thin films on silicon. Here we report on the electro-optical properties of thin barium titanate films epitaxially grown on silicon substrates. We extract a large effective Pockels coefficient of reff=148 pm V-1, which is five times larger than in the current standard material for electro-optical devices, lithium niobate. We also reveal the tensor nature of the electro-optical properties, as necessary for properly designing future devices, and furthermore unambiguously demonstrate the presence of ferroelectricity. The integration of electro-optical active films on silicon could pave the way towards power-efficient, ultra-compact integrated devices, such as modulators, tuning elements and bistable switches.

Reconfigurable radio-frequency arbitrary waveforms synthesized in a silicon photonic chip.

PubMed

Wang, Jian; Shen, Hao; Fan, Li; Wu, Rui; Niu, Ben; Varghese, Leo T; Xuan, Yi; Leaird, Daniel E; Wang, Xi; Gan, Fuwan; Weiner, Andrew M; Qi, Minghao

2015-01-12

Photonic methods of radio-frequency waveform generation and processing can provide performance advantages and flexibility over electronic methods due to the ultrawide bandwidth offered by the optical carriers. However, bulk optics implementations suffer from the lack of integration and slow reconfiguration speed. Here we propose an architecture of integrated photonic radio-frequency generation and processing and implement it on a silicon chip fabricated in a semiconductor manufacturing foundry. Our device can generate programmable radio-frequency bursts or continuous waveforms with only the light source, electrical drives/controls and detectors being off-chip. It modulates an individual pulse in a radio-frequency burst within 4 ns, achieving a reconfiguration speed three orders of magnitude faster than thermal tuning. The on-chip optical delay elements offer an integrated approach to accurately manipulating individual radio-frequency waveform features without constraints set by the speed and timing jitter of electronics, and should find applications ranging from high-speed wireless to defence electronics.

Error and Complexity Analysis for a Collocation-Grid-Projection Plus Precorrected-FFT Algorithm for Solving Potential Integral Equations with LaPlace or Helmholtz Kernels

NASA Technical Reports Server (NTRS)

Phillips, J. R.

1996-01-01

In this paper we derive error bounds for a collocation-grid-projection scheme tuned for use in multilevel methods for solving boundary-element discretizations of potential integral equations. The grid-projection scheme is then combined with a precorrected FFT style multilevel method for solving potential integral equations with 1/r and e(sup ikr)/r kernels. A complexity analysis of this combined method is given to show that for homogeneous problems, the method is order n natural log n nearly independent of the kernel. In addition, it is shown analytically and experimentally that for an inhomogeneity generated by a very finely discretized surface, the combined method slows to order n(sup 4/3). Finally, examples are given to show that the collocation-based grid-projection plus precorrected-FFT scheme is competitive with fast-multipole algorithms when considering realistic problems and 1/r kernels, but can be used over a range of spatial frequencies with only a small performance penalty.

Reconfigurable radio-frequency arbitrary waveforms synthesized in a silicon photonic chip

PubMed Central

Wang, Jian; Shen, Hao; Fan, Li; Wu, Rui; Niu, Ben; Varghese, Leo T.; Xuan, Yi; Leaird, Daniel E.; Wang, Xi; Gan, Fuwan; Weiner, Andrew M.; Qi, Minghao

2015-01-01

Photonic methods of radio-frequency waveform generation and processing can provide performance advantages and flexibility over electronic methods due to the ultrawide bandwidth offered by the optical carriers. However, bulk optics implementations suffer from the lack of integration and slow reconfiguration speed. Here we propose an architecture of integrated photonic radio-frequency generation and processing and implement it on a silicon chip fabricated in a semiconductor manufacturing foundry. Our device can generate programmable radio-frequency bursts or continuous waveforms with only the light source, electrical drives/controls and detectors being off-chip. It modulates an individual pulse in a radio-frequency burst within 4 ns, achieving a reconfiguration speed three orders of magnitude faster than thermal tuning. The on-chip optical delay elements offer an integrated approach to accurately manipulating individual radio-frequency waveform features without constraints set by the speed and timing jitter of electronics, and should find applications ranging from high-speed wireless to defence electronics. PMID:25581847

iTunes U: An Opportunity for Students

ERIC Educational Resources Information Center

Germany, Lisa

2011-01-01

Purpose: The aim of this paper is to demonstrate that, with a bit of creative thinking, elements of certain university-wide projects (in this case study, establishing an iTunes U site) can be incorporated into student studies and assessment as real-world learning opportunities. Design/methodology/approach: Describes three different approaches…

Structural Acoustic Prediction and Interior Noise Control Technology

NASA Technical Reports Server (NTRS)

Mathur, G. P.; Chin, C. L.; Simpson, M. A.; Lee, J. T.; Palumbo, Daniel L. (Technical Monitor)

2001-01-01

This report documents the results of Task 14, "Structural Acoustic Prediction and Interior Noise Control Technology". The task was to evaluate the performance of tuned foam elements (termed Smart Foam) both analytically and experimentally. Results taken from a three-dimensional finite element model of an active, tuned foam element are presented. Measurements of sound absorption and sound transmission loss were taken using the model. These results agree well with published data. Experimental performance data were taken in Boeing's Interior Noise Test Facility where 12 smart foam elements were applied to a 757 sidewall. Several configurations were tested. Noise reductions of 5-10 dB were achieved over the 200-800 Hz bandwidth of the controller. Accelerometers mounted on the panel provided a good reference for the controller. Configurations with far-field error microphones outperformed near-field cases.

Performance analysis of different tuning rules for an isothermal CSTR using integrated EPC and SPC

NASA Astrophysics Data System (ADS)

Roslan, A. H.; Karim, S. F. Abd; Hamzah, N.

2018-03-01

This paper demonstrates the integration of Engineering Process Control (EPC) and Statistical Process Control (SPC) for the control of product concentration of an isothermal CSTR. The objectives of this study are to evaluate the performance of Ziegler-Nichols (Z-N), Direct Synthesis, (DS) and Internal Model Control (IMC) tuning methods and determine the most effective method for this process. The simulation model was obtained from past literature and re-constructed using SIMULINK MATLAB to evaluate the process response. Additionally, the process stability, capability and normality were analyzed using Process Capability Sixpack reports in Minitab. Based on the results, DS displays the best response for having the smallest rise time, settling time, overshoot, undershoot, Integral Time Absolute Error (ITAE) and Integral Square Error (ISE). Also, based on statistical analysis, DS yields as the best tuning method as it exhibits the highest process stability and capability.

Spatial reference frames of visual, vestibular, and multimodal heading signals in the dorsal subdivision of the medial superior temporal area.

PubMed

Fetsch, Christopher R; Wang, Sentao; Gu, Yong; Deangelis, Gregory C; Angelaki, Dora E

2007-01-17

Heading perception is a complex task that generally requires the integration of visual and vestibular cues. This sensory integration is complicated by the fact that these two modalities encode motion in distinct spatial reference frames (visual, eye-centered; vestibular, head-centered). Visual and vestibular heading signals converge in the primate dorsal subdivision of the medial superior temporal area (MSTd), a region thought to contribute to heading perception, but the reference frames of these signals remain unknown. We measured the heading tuning of MSTd neurons by presenting optic flow (visual condition), inertial motion (vestibular condition), or a congruent combination of both cues (combined condition). Static eye position was varied from trial to trial to determine the reference frame of tuning (eye-centered, head-centered, or intermediate). We found that tuning for optic flow was predominantly eye-centered, whereas tuning for inertial motion was intermediate but closer to head-centered. Reference frames in the two unimodal conditions were rarely matched in single neurons and uncorrelated across the population. Notably, reference frames in the combined condition varied as a function of the relative strength and spatial congruency of visual and vestibular tuning. This represents the first investigation of spatial reference frames in a naturalistic, multimodal condition in which cues may be integrated to improve perceptual performance. Our results compare favorably with the predictions of a recent neural network model that uses a recurrent architecture to perform optimal cue integration, suggesting that the brain could use a similar computational strategy to integrate sensory signals expressed in distinct frames of reference.

Dynamical mechanism for sharp orientation tuning in an integrate-and-fire model of a cortical hypercolumn.

PubMed

Bressloff, P C; Bressloff, N W; Cowan, J D

2000-11-01

Orientation tuning in a ring of pulse-coupled integrate-and-fire (IF) neurons is analyzed in terms of spontaneous pattern formation. It is shown how the ring bifurcates from a synchronous state to a non-phase-locked state whose spike trains are characterized by clustered but irregular fluctuations of the interspike intervals (ISIs). The separation of these clusters in phase space results in a localized peak of activity as measured by the time-averaged firing rate of the neurons. This generates a sharp orientation tuning curve that can lock to a slowly rotating, weakly tuned external stimulus. Under certain conditions, the peak can slowly rotate even to a fixed external stimulus. The ring also exhibits hysteresis due to the subcritical nature of the bifurcation to sharp orientation tuning. Such behavior is shown to be consistent with a corresponding analog version of the IF model in the limit of slow synaptic interactions. For fast synapses, the deterministic fluctuations of the ISIs associated with the tuning curve can support a coefficient of variation of order unity.

Application of a system modification technique to dynamic tuning of a spinning rotor blade

NASA Technical Reports Server (NTRS)

Spain, C. V.

1987-01-01

An important consideration in the development of modern helicopters is the vibratory response of the main rotor blade. One way to minimize vibration levels is to ensure that natural frequencies of the spinning main rotor blade are well removed from integer multiples of the rotor speed. A technique for dynamically tuning a finite-element model of a rotor blade to accomplish that end is demonstrated. A brief overview is given of the general purpose finite element system known as Engineering Analysis Language (EAL) which was used in this work. A description of the EAL System Modification (SM) processor is then given along with an explanation of special algorithms developed to be used in conjunction with SM. Finally, this technique is demonstrated by dynamically tuning a model of an advanced composite rotor blade.

Monolithic beam steering in a mid-infrared, surface-emitting, photonic integrated circuit.

PubMed

Slivken, Steven; Wu, Donghai; Razeghi, Manijeh

2017-08-16

The mid-infrared (2.5 < λ < 25 μm) spectral region is utilized for many purposes, such as chemical/biological sensing, free space communications, and illuminators/countermeasures. Compared to near-infrared optical systems, however, mid-infrared component technology is still rather crude, with isolated components exhibiting limited functionality. In this manuscript, we make a significant leap forward in mid-infrared technology by developing a platform which can combine functions of multiple mid-infrared optical elements, including an integrated light source. In a single device, we demonstrate wide wavelength tuning (240 nm) and beam steering (17.9 degrees) in the mid-infrared with a significantly reduced beam divergence (down to 0.5 degrees). The architecture is also set up to be manufacturable and testable on a wafer scale, requiring no cleaved facets or special mirror coating to function.

Proportional plus integral MIMO controller for regulation and tracking with anti-wind-up features

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puleston, P.F.; Mantz, R.J.

1993-11-01

A proportional plus integral matrix control structure for MIMO systems is proposed. Based on a standard optimal control structure with integral action, it permits a greater degree of independence of the design and tuning of the regulating and tracking features, without considerably increasing the controller complexity. Fast recovery from load disturbances is achieved, while large overshoots associated with set-point changes and reset wind-up problems can be reduced. A simple effective procedure for practical tuning is introduced.

All-fibre ytterbium laser tunable within 45 nm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdullina, S R; Babin, S A; Vlasov, A A

2007-12-31

A tunable ytterbium-doped fibre laser is fabricated. The laser is tuned by using a tunable fibre Bragg grating (FBG) as a selecting intracavity element. The laser is tunable within 45 nm (from 1063 to 1108 nm) and emits {approx}6 W in the line of width {approx}0.15 nm, the output power and linewidth being virtually invariable within the tuning range. The method is proposed for synchronous tuning the highly reflecting and output FBGs, and a tunable ytterbium all-fibre laser is built. (lasers)

ANSYS simulation of the capacitance coupling of quartz tuning fork gyroscope

NASA Astrophysics Data System (ADS)

Zhang, Qing; Feng, Lihui; Zhao, Ke; Cui, Fang; Sun, Yu-nan

2013-12-01

Coupling error is one of the main error sources of the quartz tuning fork gyroscope. The mechanism of capacitance coupling error is analyzed in this article. Finite Element Method (FEM) is used to simulate the structure of the quartz tuning fork by ANSYS software. The voltage output induced by the capacitance coupling is simulated with the harmonic analysis and characteristics of electrical and mechanical parameters influenced by the capacitance coupling between drive electrodes and sense electrodes are discussed with the transient analysis.

Dielectric Elastomer Actuated Systems and Methods

NASA Technical Reports Server (NTRS)

Dubowsky, Steven (Inventor); Hafez, Moustapha (Inventor); Lichter, Matthew (Inventor); Weiss, Peter (Inventor); Wingert, Andreas (Inventor)

2008-01-01

The system of the present invention includes an actuator having at least two electrodes, an elastomeric dielectric film disposed between the two electrodes, and a frame attached to the elastomeric dielectric film. The frame provides a linear actuation force characteristic over a displacement range. The displacement range is preferably the stroke of the actuator. The displacement range can be about 5 mm and greater. Further, the frame can include a plurality of configurations, for example, at least a rigid members coupled to a flexible member wherein the frame provides an elastic restoring force. In preferred embodiments, the rigid member can be, but is not limited to, curved beams, parallel beams, rods and plates. In a preferred embodiment the actuator can further include a passive element disposed between two flexible members such as, for example, links to tune a stiffness characteristic of the actuator. The passive element can be a bi-stable element. Further, the actuator can include a plurality of layers of the elastomeric dielectric film integrated into the frame. The elastomeric film can be made of different materials such as, for example, acrylic, silicone and latex.

Elastomeric actuator devices for magnetic resonance imaging

NASA Technical Reports Server (NTRS)

Lichter, Matthew (Inventor); Wingert, Andreas (Inventor); Hafez, Moustapha (Inventor); Dubowsky, Steven (Inventor); Jolesz, Ferenc A. (Inventor); Kacher, Daniel F. (Inventor); Weiss, Peter (Inventor)

2008-01-01

The present invention is directed to devices and systems used in magnetic imaging environments that include an actuator device having an elastomeric dielectric film with at least two electrodes, and a frame attached to the actuator device. The frame can have a plurality of configurations including, such as, for example, at least two members that can be, but not limited to, curved beams, rods, plates, or parallel beams. These rigid members can be coupled to flexible members such as, for example, links wherein the frame provides an elastic restoring force. The frame preferably provides a linear actuation force characteristic over a displacement range. The linear actuation force characteristic is defined as .+-.20% and preferably 10% over a displacement range. The actuator further includes a passive element disposed between the flexible members to tune a stiffness characteristic of the actuator. The passive element can be a bi-stable element. The preferred embodiment actuator includes one or more layers of the elastomeric film integrated into the frame. The elastomeric film can be made of many elastomeric materials such as, for example, but not limited to, acrylic, silicone and latex.

Multi-Objective Control Optimization for Greenhouse Environment Using Evolutionary Algorithms

PubMed Central

Hu, Haigen; Xu, Lihong; Wei, Ruihua; Zhu, Bingkun

2011-01-01

This paper investigates the issue of tuning the Proportional Integral and Derivative (PID) controller parameters for a greenhouse climate control system using an Evolutionary Algorithm (EA) based on multiple performance measures such as good static-dynamic performance specifications and the smooth process of control. A model of nonlinear thermodynamic laws between numerous system variables affecting the greenhouse climate is formulated. The proposed tuning scheme is tested for greenhouse climate control by minimizing the integrated time square error (ITSE) and the control increment or rate in a simulation experiment. The results show that by tuning the gain parameters the controllers can achieve good control performance through step responses such as small overshoot, fast settling time, and less rise time and steady state error. Besides, it can be applied to tuning the system with different properties, such as strong interactions among variables, nonlinearities and conflicting performance criteria. The results implicate that it is a quite effective and promising tuning method using multi-objective optimization algorithms in the complex greenhouse production. PMID:22163927

Femtosecond laser-induced inverted microstructures inside glasses by tuning refractive index of objective's immersion liquid.

PubMed

Luo, Fangfang; Song, Juan; Hu, Xiao; Sun, Haiyi; Lin, Geng; Pan, Huaihai; Cheng, Ya; Liu, Li; Qiu, Jianrong; Zhao, Quanzhong; Xu, Zhizhan

2011-06-01

We report the formation of inverted microstructures inside glasses after femtosecond laser irradiation by tuning the refractive index contrast between the immersion liquid and the glass sample. By using water as well as 1-bromonaphthalene as immersion liquids, microstructures with similar shape but opposite directions are induced after femtosecond laser irradiation. Interestingly, the elemental distribution in the induced structures is also inverted. The simulation of laser intensity distribution along the laser propagation direction indicates that the interfacial spherical aberration effect is responsible for the inversion of microstructures and elemental distribution. © 2011 Optical Society of America

Quasi-continuous frequency tunable terahertz quantum cascade lasers with coupled cavity and integrated photonic lattice.

PubMed

Kundu, Iman; Dean, Paul; Valavanis, Alexander; Chen, Li; Li, Lianhe; Cunningham, John E; Linfield, Edmund H; Davies, A Giles

2017-01-09

We demonstrate quasi-continuous tuning of the emission frequency from coupled cavity terahertz frequency quantum cascade lasers. Such coupled cavity lasers comprise a lasing cavity and a tuning cavity which are optically coupled through a narrow air slit and are operated above and below the lasing threshold current, respectively. The emission frequency of these devices is determined by the Vernier resonance of longitudinal modes in the lasing and the tuning cavities, and can be tuned by applying an index perturbation in the tuning cavity. The spectral coverage of the coupled cavity devices have been increased by reducing the repetition frequency of the Vernier resonance and increasing the ratio of the free spectral ranges of the two cavities. A continuous tuning of the coupled cavity modes has been realized through an index perturbation of the lasing cavity itself by using wide electrical heating pulses at the tuning cavity and exploiting thermal conduction through the monolithic substrate. Single mode emission and discrete frequency tuning over a bandwidth of 100 GHz and a quasi-continuous frequency coverage of 7 GHz at 2.25 THz is demonstrated. An improvement in the side mode suppression and a continuous spectral coverage of 3 GHz is achieved without any degradation of output power by integrating a π-phase shifted photonic lattice in the laser cavity.

Creating a Test Validated Structural Dynamic Finite Element Model of the Multi-Utility Technology Test Bed Aircraft

NASA Technical Reports Server (NTRS)

Pak, Chan-Gi; Truong, Samson S.

2014-01-01

Small modeling errors in the finite element model will eventually induce errors in the structural flexibility and mass, thus propagating into unpredictable errors in the unsteady aerodynamics and the control law design. One of the primary objectives of Multi Utility Technology Test Bed, X-56A, aircraft is the flight demonstration of active flutter suppression, and therefore in this study, the identification of the primary and secondary modes for the structural model tuning based on the flutter analysis of X-56A. The ground vibration test validated structural dynamic finite element model of the X-56A is created in this study. The structural dynamic finite element model of the X-56A is improved using a model tuning tool. In this study, two different weight configurations of the X-56A have been improved in a single optimization run.

Logic elements for reactor period meter

DOEpatents

McDowell, William P.; Bobis, James P.

1976-01-01

Logic elements are provided for a reactor period meter trip circuit. For one element, first and second inputs are applied to first and second chopper comparators, respectively. The output of each comparator is O if the input applied to it is greater than or equal to a trip level associated with each input and each output is a square wave of frequency f if the input applied to it is less than the associated trip level. The outputs of the comparators are algebraically summed and applied to a bandpass filter tuned to f. For another element, the output of each comparator is applied to a bandpass filter which is tuned to f to give a sine wave of frequency f. The outputs of the filters are multiplied by an analog multiplier whose output is 0 if either input is 0 and a sine wave of frequency 2f if both inputs are a frequency f.

Extended and quasi-continuous tuning of quantum cascade lasers using superstructure gratings and integrated heaters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bidaux, Yves, E-mail: yves.bidaux@alpeslasers.ch; Institute for Quantum Electronics, ETH-Zurich, CH-8093 Zurich; Bismuto, Alfredo, E-mail: alfredo.bismuto@alpeslasers.ch

2015-11-30

In this work, we demonstrate broad electrical tuning of quantum cascade lasers at 9.25 μm, 8.5 μm, and 4.4 μm in continuous wave operation using Vernier-effect distributed Bragg reflectors based on superstructure gratings. Integrated micro-heaters allow to switch from one Vernier channel to the other, while predictable and mode-hop free tuning can be obtained in each channel modulating the laser current with a side mode suppression ratio as high as 30 dB. The resulting device behaves effectively as a switchable multicolour tunable source. Tuning up to 6.5% of the central wavelength is observed. To prove the importance of the developed devices for high resolutionmore » molecular spectroscopy, a N{sub 2}O absorption spectrum has been measured.« less

Tunable impedance matching network fundamental limits and practical considerations

NASA Astrophysics Data System (ADS)

Allen, Wesley N.

As wireless devices continue to increase in utility while decreasing in dimension, design of the RF front-end becomes more complex. It is common for a single handheld device to operate on a plethora of frequency bands, utilize multiple antennae, and be subjected to a variety of environments. One complexity in particular which arises from these factors is that of impedance mismatch. Recently, tunable impedance matching networks have begun to be implemented to address this problem. This dissertation presents the first in-depth study on the frequency tuning range of tunable impedance matching networks. Both the fundamental limitations of ideal networks as well as practical considerations for design and implementation are addressed. Specifically, distributed matching networks with a single tuning element are investigated for use with parallel resistor-capacitor and series resistor-inductor loads. Analytical formulas are developed to directly calculate the frequency tuning range TR of ideal topologies. The theoretical limit of TR for these topologies is presented and discussed. Additional formulas are developed which address limitations in transmission line characteristic impedance and varactor range. Equations to predict loss due to varactor quality factor are demonstrated and the ability of parasitics to both increase and decrease TR are shown. Measured results exemplify i) the potential to develop matching networks with a small impact from parasitics, ii) the need for accurate knowledge of parasitics when designing near transition points in optimal parameters, iii) the importance of using a transmission line with the right characteristic impedance, and iv) the ability to achieve extremely low loss at the design frequency with a lossy varactor under the right conditions (measured loss of -0.07 dB). In the area of application, tunable matching networks are designed and measured for mobile handset antennas, demonstrating up to a 3 dB improvement in power delivered to a planar inverted-F antenna and up to 4--5.6 dB improvement in power delivered to the iPhone(TM) antenna. Additionally, a single-varactor matching network is measured to achieve greater tuning range than a two-varactor matching network (> 824--960 MHz versus 850--915 MHz) and yield higher power handling. Addressing miniaturization, an accurate model of metal loss in planar integrated inductors for low-loss substrates is developed and demonstrated. Finally, immediate future research directions are suggested: i) expanding the topologies, tuning elements, and loads analyzed; ii) performing a deep study into parasitics; and iii) investigating power handling with various varactor technologies.

Algorithms to automate gap-dependent integral tuning for the 2.8-meter long horizontal field undulator with a dynamic force compensation mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Joseph Z., E-mail: x@anl.gov; Vasserman, Isaac; Strelnikov, Nikita

2016-07-27

A 2.8-meter long horizontal field prototype undulator with a dynamic force compensation mechanism has been developed and tested at the Advanced Photon Source (APS) at Argonne National Laboratory (Argonne). The magnetic tuning of the undulator integrals has been automated and accomplished by applying magnetic shims. A detailed description of the algorithms and performance is reported.

Chalcogenide glass sensors for bio-molecule detection

NASA Astrophysics Data System (ADS)

Lucas, Pierre; Coleman, Garrett J.; Cantoni, Christopher; Jiang, Shibin; Luo, Tao; Bureau, Bruno; Boussard-Pledel, Catherine; Troles, Johann; Yang, Zhiyong

2017-02-01

Chalcogenide glasses constitute the only class of materials that remain fully amorphous while exhibiting broad optical transparency over the full infrared region from 2-20 microns. As such, they can be shaped into complex optical elements while retaining a clear optical window that encompass the vibrational signals of virtually any molecules. Chalcogenide glasses are therefore ideal materials for designing biological and chemical sensors based on vibrational spectroscopy. In this paper we review the properties of these glasses and the corresponding design of optical elements for bio-chemical sensing. Amorphous chalcogenides offer a very wide compositional landscape that permit to tune their physical properties to match specific demands for the production of optical devices. This includes tailoring the infrared window over specific ranges of wavelength such as the long-wave infrared region to capture important vibrational signal including the "signature region" of micro-organisms or the bending mode of CO2 molecules. Additionally, compositional engineering enables tuning the viscosity-temperature dependence of the glass melt in order to control the rheological properties that are fundamental to the production of glass elements. Indeed, exquisite control of the viscosity is key to the fabrication process of many optical elements such as fiber drawing, lens molding, surface embossing or reflow of microresonators. Optimal control of these properties then enables the design and fabrication of optimized infrared sensors such as Fiber Evanescent Wave Spectroscopy (FEWS) sensors, Whispering Gallery Modes (WGM) micro-resonator sensors, nanostructured surfaces for integrated optics and surface-enhanced processes, or lens molding for focused collection of infrared signals. Many of these sensor designs can be adapted to collect and monitor the vibrational signal of live microorganisms to study their metabolism in controlled environmental conditions. Further materials engineering enable the design of opto-electrophoretic sensors that permit simultaneous capture and detection of hazardous bio-molecules such as bacteria, virus and proteins using a conducting glass that serves as both an electrode and an optical elements. Upon adequate spectral analysis such as Principal Component Analysis (PCA) or Partial Least Square (PLS) regression these devices enable highly selective identification of hazardous microorganism such as different strains of bacteria and food pathogens.

Optimization of PID Parameters Utilizing Variable Weight Grey-Taguchi Method and Particle Swarm Optimization

NASA Astrophysics Data System (ADS)

Azmi, Nur Iffah Mohamed; Arifin Mat Piah, Kamal; Yusoff, Wan Azhar Wan; Romlay, Fadhlur Rahman Mohd

2018-03-01

Controller that uses PID parameters requires a good tuning method in order to improve the control system performance. Tuning PID control method is divided into two namely the classical methods and the methods of artificial intelligence. Particle swarm optimization algorithm (PSO) is one of the artificial intelligence methods. Previously, researchers had integrated PSO algorithms in the PID parameter tuning process. This research aims to improve the PSO-PID tuning algorithms by integrating the tuning process with the Variable Weight Grey- Taguchi Design of Experiment (DOE) method. This is done by conducting the DOE on the two PSO optimizing parameters: the particle velocity limit and the weight distribution factor. Computer simulations and physical experiments were conducted by using the proposed PSO- PID with the Variable Weight Grey-Taguchi DOE and the classical Ziegler-Nichols methods. They are implemented on the hydraulic positioning system. Simulation results show that the proposed PSO-PID with the Variable Weight Grey-Taguchi DOE has reduced the rise time by 48.13% and settling time by 48.57% compared to the Ziegler-Nichols method. Furthermore, the physical experiment results also show that the proposed PSO-PID with the Variable Weight Grey-Taguchi DOE tuning method responds better than Ziegler-Nichols tuning. In conclusion, this research has improved the PSO-PID parameter by applying the PSO-PID algorithm together with the Variable Weight Grey-Taguchi DOE method as a tuning method in the hydraulic positioning system.

A high-speed, tunable silicon photonic ring modulator integrated with ultra-efficient active wavelength control.

PubMed

Zheng, Xuezhe; Chang, Eric; Amberg, Philip; Shubin, Ivan; Lexau, Jon; Liu, Frankie; Thacker, Hiren; Djordjevic, Stevan S; Lin, Shiyun; Luo, Ying; Yao, Jin; Lee, Jin-Hyoung; Raj, Kannan; Ho, Ron; Cunningham, John E; Krishnamoorthy, Ashok V

2014-05-19

We report the first complete 10G silicon photonic ring modulator with integrated ultra-efficient CMOS driver and closed-loop wavelength control. A selective substrate removal technique was used to improve the ring tuning efficiency. Limited by the thermal tuner driver output power, a maximum open-loop tuning range of about 4.5nm was measured with about 14mW of total tuning power including the heater driver circuit power consumption. Stable wavelength locking was achieved with a low-power mixed-signal closed-loop wavelength controller. An active wavelength tracking range of > 500GHz was demonstrated with controller energy cost of only 20fJ/bit.

A dual frequency microstrip antenna for Ka band

NASA Technical Reports Server (NTRS)

Lee, R. Q.; Baddour, M. F.

1985-01-01

For fixed satellite communication systems at Ka band with downlink at 17.7 to 20.2 GHz and uplink at 27.5 to 30.0 GHz, the focused optics and the unfocused optics configurations with monolithic phased array feeds have often been used to provide multiple fixed and multiple scanning spot beam coverages. It appears that a dual frequency microstrip antenna capable of transmitting and receiving simultaneously is highly desirable as an array feed element. This paper describes some early efforts on the development and experimental testing of a dual frequency annular microstrip antenna. The antenna has potential application for use in conjunction with a monolithic microwave integrated circuit device as an active radiating element in a phased array of phased array feeds. The antenna is designed to resonate at TM sub 12 and TM sub 13 modes and tuned with a circumferential microstrip ring to vary the frequency ratio. Radiation characteristics at both the high and low frequencies are examined. Experimental results including radiating patterns and swept frequency measurements are presented.

Geometrical tuning art for entirely subwavelength grating waveguide based integrated photonics circuits

DOE PAGES

Wang, Zheng; Xu, Xiaochuan; Fan, Donglei; ...

2016-05-05

Here, subwavelength grating (SWG) waveguide is an intriguing alternative to conventional optical waveguides due to the extra degree of freedom it offers in tuning a few important waveguide properties, such as dispersion and refractive index. Devices based on SWG waveguides have demonstrated impressive performances compared to conventional waveguides. However, the high loss of SWG waveguide bends jeopardizes their applications in integrated photonic circuits. In this work, we propose a geometrical tuning art, which realizes a pre-distorted refractive index profile in SWG waveguide bends. The pre-distorted refractive index profile can effectively reduce the mode mismatch and radiation loss simultaneously, thus significantlymore » reduce the bend loss. This geometry tuning art has been numerically optimized and experimentally demonstrated in present study. Through such tuning, the average insertion loss of a 5 μm SWG waveguide bend is reduced drastically from 5.43 dB to 1.10 dB per 90° bend for quasi-TE polarization. In the future, the proposed scheme will be utilized to enhance performance of a wide range of SWG waveguide based photonics devices.« less

Integrating Cache Performance Modeling and Tuning Support in Parallelization Tools

NASA Technical Reports Server (NTRS)

Waheed, Abdul; Yan, Jerry; Saini, Subhash (Technical Monitor)

1998-01-01

With the resurgence of distributed shared memory (DSM) systems based on cache-coherent Non Uniform Memory Access (ccNUMA) architectures and increasing disparity between memory and processors speeds, data locality overheads are becoming the greatest bottlenecks in the way of realizing potential high performance of these systems. While parallelization tools and compilers facilitate the users in porting their sequential applications to a DSM system, a lot of time and effort is needed to tune the memory performance of these applications to achieve reasonable speedup. In this paper, we show that integrating cache performance modeling and tuning support within a parallelization environment can alleviate this problem. The Cache Performance Modeling and Prediction Tool (CPMP), employs trace-driven simulation techniques without the overhead of generating and managing detailed address traces. CPMP predicts the cache performance impact of source code level "what-if" modifications in a program to assist a user in the tuning process. CPMP is built on top of a customized version of the Computer Aided Parallelization Tools (CAPTools) environment. Finally, we demonstrate how CPMP can be applied to tune a real Computational Fluid Dynamics (CFD) application.

Geometrical tuning art for entirely subwavelength grating waveguide based integrated photonics circuits

PubMed Central

Wang, Zheng; Xu, Xiaochuan; Fan, Donglei; Wang, Yaguo; Subbaraman, Harish; Chen, Ray T.

2016-01-01

Subwavelength grating (SWG) waveguide is an intriguing alternative to conventional optical waveguides due to the extra degree of freedom it offers in tuning a few important waveguide properties, such as dispersion and refractive index. Devices based on SWG waveguides have demonstrated impressive performances compared to conventional waveguides. However, the high loss of SWG waveguide bends jeopardizes their applications in integrated photonic circuits. In this work, we propose a geometrical tuning art, which realizes a pre-distorted refractive index profile in SWG waveguide bends. The pre-distorted refractive index profile can effectively reduce the mode mismatch and radiation loss simultaneously, thus significantly reduce the bend loss. This geometry tuning art has been numerically optimized and experimentally demonstrated in present study. Through such tuning, the average insertion loss of a 5 μm SWG waveguide bend is reduced drastically from 5.43 dB to 1.10 dB per 90° bend for quasi-TE polarization. In the future, the proposed scheme will be utilized to enhance performance of a wide range of SWG waveguide based photonics devices. PMID:27145872

Geometrical tuning art for entirely subwavelength grating waveguide based integrated photonics circuits.

PubMed

Wang, Zheng; Xu, Xiaochuan; Fan, Donglei; Wang, Yaguo; Subbaraman, Harish; Chen, Ray T

2016-05-05

Subwavelength grating (SWG) waveguide is an intriguing alternative to conventional optical waveguides due to the extra degree of freedom it offers in tuning a few important waveguide properties, such as dispersion and refractive index. Devices based on SWG waveguides have demonstrated impressive performances compared to conventional waveguides. However, the high loss of SWG waveguide bends jeopardizes their applications in integrated photonic circuits. In this work, we propose a geometrical tuning art, which realizes a pre-distorted refractive index profile in SWG waveguide bends. The pre-distorted refractive index profile can effectively reduce the mode mismatch and radiation loss simultaneously, thus significantly reduce the bend loss. This geometry tuning art has been numerically optimized and experimentally demonstrated in present study. Through such tuning, the average insertion loss of a 5 μm SWG waveguide bend is reduced drastically from 5.43 dB to 1.10 dB per 90° bend for quasi-TE polarization. In the future, the proposed scheme will be utilized to enhance performance of a wide range of SWG waveguide based photonics devices.

Tuning the DARHT Axis-II linear induction accelerator focusing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ekdahl, Carl A.

2012-04-24

Flash radiography of large hydrodynamic experiments driven by high explosives is a well-known diagnostic technique in use at many laboratories, and the Dual-Axis Radiography for Hydrodynamic Testing (DARHT) facility at Los Alamos produces flash radiographs of large hydrodynamic experiments. Two linear induction accelerators (LIAs) make the bremsstrahlung radiographic source spots for orthogonal views of each test. The 2-kA, 20-MeV Axis-I LIA creates a single 60-ns radiography pulse. The 1.7-kA, 16.5-MeV Axis-II LIA creates up to four radiography pulses by kicking them out of a longer pulse that has a 1.6-{mu}s flattop. The Axis-II injector, LIA, kicker, and downstream transport (DST)more » to the bremsstrahlung converter are described. Adjusting the magnetic focusing and steering elements to optimize the electron-beam transport through an LIA is often called 'tuning.' As in all high-current LIAs, the focusing field is designed to be as close to that of the ideal continuous solenoid as physically possible. In ideal continuous solenoidal transport a smoothly varying beam size can easily be found for which radial forces balance, and the beam is said to be 'matched' to the focusing field. A 'mismatched' beam exhibits unwanted oscillations in size, which are a source of free energy that contributes to emittance growth. This is undesirable, because in the absence of beam-target effects, the radiographic spot size is proportional to the emittance. Tuning the Axis-II LIA is done in two steps. First, the solenoidal focusing elements are set to values designed to provide a matched beam with little or no envelope oscillations, and little or no beam-breakup (BBU) instability growth. Then, steering elements are adjusted to minimize the motion of the centroid of a well-centered beam at the LIA exit. This article only describes the design of the tune for the focusing solenoids. The DARHT Axis-II LIA was required to be re-tuned after installing an accelerator cell to replace a failed solenoid in March of 2012. We took advantage of this opportunity to improve the design of the focusing tune with better models of the remaining partially failed solenoids, better estimates of beam initial conditions, and better values for pulsed-power voltages. As with all previous tunes for Axis-II, this one incorporates measures to mitigate beam-breakup (BBU) instability, image displacement instability (IDI), corkscrew (sweep), and emittance growth. Section II covers the general approach to of design of focusing solenoid tunes for the DARHT Axis-2 LIA. Section III explains the specific requirements and simulations needed to design the tune for the injector, which includes the thermionic electron source, diode, and six induction cells. Section IV explains the requirements and simulations for tuning the main accelerator, which consists of 68 induction cells. Finally, Section V explores sensitivity of the tune to deviations of parameters from nominal, random variations, and uncertainties in values. Four appendices list solenoid settings for this new tune, discuss comparisons of different simulation codes, show halo formation in mismatched beams, and present a brief discussion of the beam envelope equation, which is the heart of the method used to design LIA solenoid tunes.« less

Energy consumption optimization of the total-FETI solver by changing the CPU frequency

NASA Astrophysics Data System (ADS)

Horak, David; Riha, Lubomir; Sojka, Radim; Kruzik, Jakub; Beseda, Martin; Cermak, Martin; Schuchart, Joseph

2017-07-01

The energy consumption of supercomputers is one of the critical problems for the upcoming Exascale supercomputing era. The awareness of power and energy consumption is required on both software and hardware side. This paper deals with the energy consumption evaluation of the Finite Element Tearing and Interconnect (FETI) based solvers of linear systems, which is an established method for solving real-world engineering problems. We have evaluated the effect of the CPU frequency on the energy consumption of the FETI solver using a linear elasticity 3D cube synthetic benchmark. In this problem, we have evaluated the effect of frequency tuning on the energy consumption of the essential processing kernels of the FETI method. The paper provides results for two types of frequency tuning: (1) static tuning and (2) dynamic tuning. For static tuning experiments, the frequency is set before execution and kept constant during the runtime. For dynamic tuning, the frequency is changed during the program execution to adapt the system to the actual needs of the application. The paper shows that static tuning brings up 12% energy savings when compared to default CPU settings (the highest clock rate). The dynamic tuning improves this further by up to 3%.

Electrical tuning of the polarization state of light using graphene-integrated anisotropic metasurfaces

NASA Astrophysics Data System (ADS)

Dutta-Gupta, Shourya; Dabidian, Nima; Kholmanov, Iskandar; Belkin, Mikhail A.; Shvets, Gennady

2017-03-01

Plasmonic metasurfaces have been employed for moulding the flow of transmitted and reflected light, thereby enabling numerous applications that benefit from their ultra-thin sub-wavelength format. Their appeal is further enhanced by the incorporation of active electro-optic elements, paving the way for dynamic control of light's properties. In this paper, we realize a dynamic polarization state generator using a graphene-integrated anisotropic metasurface (GIAM) that converts the linear polarization of the incident light into an elliptical one. This is accomplished by using an anisotropic metasurface with two principal polarization axes, one of which possesses a Fano-type resonance. A gate-controlled single-layer graphene integrated with the metasurface was employed as an electro-optic element controlling the phase and intensity of light polarized along the resonant axis of the GIAM. When the incident light is polarized at an angle to the resonant axis of the metasurface, the ellipticity of the reflected light can be dynamically controlled by the application of a gate voltage. Thus accomplished dynamic polarization control is experimentally demonstrated and characterized by measuring the Stokes polarization parameters. Large changes of the ellipticity and the tilt angle of the polarization ellipse are observed. Our measurements show that the tilt angle can be changed from positive values through zero to negative values while keeping the ellipticity constant, potentially paving the way to rapid ellipsometry and other characterization techniques requiring fast polarization shifting. This article is part of the themed issue 'New horizons for nanophotonics'.

Tunable Superconducting Split Ring Resonators

DTIC Science & Technology

2012-09-19

microwave field-strength distortion and quality- factor dependence on tuning. Feedback for changes in design and fabrication, (4) design and fabrication...elements. For many applications tuning of the resonance frequency of the SRR is needed. Classically this is done by varactor diodes. Their capacitance ... capacitance of the gap to form a resonator circuit. The advantage of such a circuit is its quite low resonance frequency compared to other structures

Temporal tuning in the bat auditory cortex is sharper when studied with natural echolocation sequences.

PubMed

Beetz, M Jerome; Hechavarría, Julio C; Kössl, Manfred

2016-06-30

Precise temporal coding is necessary for proper acoustic analysis. However, at cortical level, forward suppression appears to limit the ability of neurons to extract temporal information from natural sound sequences. Here we studied how temporal processing can be maintained in the bats' cortex in the presence of suppression evoked by natural echolocation streams that are relevant to the bats' behavior. We show that cortical neurons tuned to target-distance actually profit from forward suppression induced by natural echolocation sequences. These neurons can more precisely extract target distance information when they are stimulated with natural echolocation sequences than during stimulation with isolated call-echo pairs. We conclude that forward suppression does for time domain tuning what lateral inhibition does for selectivity forms such as auditory frequency tuning and visual orientation tuning. When talking about cortical processing, suppression should be seen as a mechanistic tool rather than a limiting element.

Programmable motion of DNA origami mechanisms.

PubMed

Marras, Alexander E; Zhou, Lifeng; Su, Hai-Jun; Castro, Carlos E

2015-01-20

DNA origami enables the precise fabrication of nanoscale geometries. We demonstrate an approach to engineer complex and reversible motion of nanoscale DNA origami machine elements. We first design, fabricate, and characterize the mechanical behavior of flexible DNA origami rotational and linear joints that integrate stiff double-stranded DNA components and flexible single-stranded DNA components to constrain motion along a single degree of freedom and demonstrate the ability to tune the flexibility and range of motion. Multiple joints with simple 1D motion were then integrated into higher order mechanisms. One mechanism is a crank-slider that couples rotational and linear motion, and the other is a Bennett linkage that moves between a compacted bundle and an expanded frame configuration with a constrained 3D motion path. Finally, we demonstrate distributed actuation of the linkage using DNA input strands to achieve reversible conformational changes of the entire structure on ∼ minute timescales. Our results demonstrate programmable motion of 2D and 3D DNA origami mechanisms constructed following a macroscopic machine design approach.

Programmable motion of DNA origami mechanisms

PubMed Central

Marras, Alexander E.; Zhou, Lifeng; Su, Hai-Jun; Castro, Carlos E.

2015-01-01

DNA origami enables the precise fabrication of nanoscale geometries. We demonstrate an approach to engineer complex and reversible motion of nanoscale DNA origami machine elements. We first design, fabricate, and characterize the mechanical behavior of flexible DNA origami rotational and linear joints that integrate stiff double-stranded DNA components and flexible single-stranded DNA components to constrain motion along a single degree of freedom and demonstrate the ability to tune the flexibility and range of motion. Multiple joints with simple 1D motion were then integrated into higher order mechanisms. One mechanism is a crank–slider that couples rotational and linear motion, and the other is a Bennett linkage that moves between a compacted bundle and an expanded frame configuration with a constrained 3D motion path. Finally, we demonstrate distributed actuation of the linkage using DNA input strands to achieve reversible conformational changes of the entire structure on ∼minute timescales. Our results demonstrate programmable motion of 2D and 3D DNA origami mechanisms constructed following a macroscopic machine design approach. PMID:25561550

Electroabsorption-modulated widely tunable DBR laser transmitter for WDM-PONs.

PubMed

Han, Liangshun; Liang, Song; Wang, Huitao; Qiao, Lijun; Xu, Junjie; Zhao, Lingjuan; Zhu, Hongliang; Wang, Baojun; Wang, Wei

2014-12-01

We present an InP based distributed Bragg reflector (DBR) laser transmitter which has a wide wavelength tuning range and a high chip output power for wavelength division multiplexing passive optical network (WDM-PON) applications. By butt-jointing InGaAsP with 1.45 µm emission wavelength as the material of the grating section, the laser wavelength can be tuned for over 13 nm by the DBR current. Accompanied by varying the chip temperature, the tuning range can be further enlarged to 16 nm. With the help of the integrated semiconductor optical amplifier (SOA), the largest chip output power is over 30 mW. The electroabsorption modulator (EAM) is integrated into the device by the selective-area growth (SAG) technique. The 3 dB small signal modulation bandwidth of the EAM is over 13 GHz. The device has both a simple tuning scheme and a simple fabrication procedure, making it suitable for low cost massive production which is desirable for WDM-PON uses.

Improved model reduction and tuning of fractional-order PI(λ)D(μ) controllers for analytical rule extraction with genetic programming.

PubMed

Das, Saptarshi; Pan, Indranil; Das, Shantanu; Gupta, Amitava

2012-03-01

Genetic algorithm (GA) has been used in this study for a new approach of suboptimal model reduction in the Nyquist plane and optimal time domain tuning of proportional-integral-derivative (PID) and fractional-order (FO) PI(λ)D(μ) controllers. Simulation studies show that the new Nyquist-based model reduction technique outperforms the conventional H(2)-norm-based reduced parameter modeling technique. With the tuned controller parameters and reduced-order model parameter dataset, optimum tuning rules have been developed with a test-bench of higher-order processes via genetic programming (GP). The GP performs a symbolic regression on the reduced process parameters to evolve a tuning rule which provides the best analytical expression to map the data. The tuning rules are developed for a minimum time domain integral performance index described by a weighted sum of error index and controller effort. From the reported Pareto optimal front of the GP-based optimal rule extraction technique, a trade-off can be made between the complexity of the tuning formulae and the control performance. The efficacy of the single-gene and multi-gene GP-based tuning rules has been compared with the original GA-based control performance for the PID and PI(λ)D(μ) controllers, handling four different classes of representative higher-order processes. These rules are very useful for process control engineers, as they inherit the power of the GA-based tuning methodology, but can be easily calculated without the requirement for running the computationally intensive GA every time. Three-dimensional plots of the required variation in PID/fractional-order PID (FOPID) controller parameters with reduced process parameters have been shown as a guideline for the operator. Parametric robustness of the reported GP-based tuning rules has also been shown with credible simulation examples. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

Tunable, diode side-pumped Er: YAG laser

DOEpatents

Hamilton, Charles E.; Furu, Laurence H.

1997-01-01

A discrete-element Er:YAG laser, side pumped by a 220 Watt peak-power InGaAs diode array, generates >500 mWatts at 2.94 .mu.m, and is tunable over a 6 nm range near about 2.936 .mu.m. The oscillator is a plano-concave resonator consisting of a concave high reflector, a flat output coupler, a Er:YAG crystal and a YAG intracavity etalon, which serves as the tuning element. The cavity length is variable from 3 cm to 4 cm. The oscillator uses total internal reflection in the Er:YAG crystal to allow efficient coupling of the diode emission into the resonating modes of the oscillator. With the tuning element removed, the oscillator produces up to 1.3 Watts of average power at 2.94 .mu.m. The duty factor of the laser is 6.5% and the repetition rate is variable up to 1 kHz. This laser is useful for tuning to an atmospheric transmission window at 2.935 .mu.m (air wavelength). The laser is also useful as a spectroscopic tool because it can access several infrared water vapor transitions, as well as transitions in organic compounds. Other uses include medical applications (e.g., for tissue ablation and uses with fiber optic laser scalpels) and as part of industrial effluent monitoring systems.

Tunable, diode side-pumped Er:YAG laser

DOEpatents

Hamilton, C.E.; Furu, L.H.

1997-04-22

A discrete-element Er:YAG laser, side pumped by a 220 Watt peak-power InGaAs diode array, generates >500 mWatts at 2.94 {micro}m, and is tunable over a 6 nm range near about 2.936 {micro}m. The oscillator is a plano-concave resonator consisting of a concave high reflector, a flat output coupler, a Er:YAG crystal and a YAG intracavity etalon, which serves as the tuning element. The cavity length is variable from 3 cm to 4 cm. The oscillator uses total internal reflection in the Er:YAG crystal to allow efficient coupling of the diode emission into the resonating modes of the oscillator. With the tuning element removed, the oscillator produces up to 1.3 Watts of average power at 2.94 {micro}m. The duty factor of the laser is 6.5% and the repetition rate is variable up to 1 kHz. This laser is useful for tuning to an atmospheric transmission window at 2.935 {micro}m (air wavelength). The laser is also useful as a spectroscopic tool because it can access several infrared water vapor transitions, as well as transitions in organic compounds. Other uses include medical applications (e.g., for tissue ablation and uses with fiber optic laser scalpels) and as part of industrial effluent monitoring systems. 4 figs.

Frequency Control of Single Quantum Emitters in Integrated Photonic Circuits

NASA Astrophysics Data System (ADS)

Schmidgall, Emma R.; Chakravarthi, Srivatsa; Gould, Michael; Christen, Ian R.; Hestroffer, Karine; Hatami, Fariba; Fu, Kai-Mei C.

2018-02-01

Generating entangled graph states of qubits requires high entanglement rates, with efficient detection of multiple indistinguishable photons from separate qubits. Integrating defect-based qubits into photonic devices results in an enhanced photon collection efficiency, however, typically at the cost of a reduced defect emission energy homogeneity. Here, we demonstrate that the reduction in defect homogeneity in an integrated device can be partially offset by electric field tuning. Using photonic device-coupled implanted nitrogen vacancy (NV) centers in a GaP-on-diamond platform, we demonstrate large field-dependent tuning ranges and partial stabilization of defect emission energies. These results address some of the challenges of chip-scale entanglement generation.

Frequency Control of Single Quantum Emitters in Integrated Photonic Circuits.

PubMed

Schmidgall, Emma R; Chakravarthi, Srivatsa; Gould, Michael; Christen, Ian R; Hestroffer, Karine; Hatami, Fariba; Fu, Kai-Mei C

2018-02-14

Generating entangled graph states of qubits requires high entanglement rates with efficient detection of multiple indistinguishable photons from separate qubits. Integrating defect-based qubits into photonic devices results in an enhanced photon collection efficiency, however, typically at the cost of a reduced defect emission energy homogeneity. Here, we demonstrate that the reduction in defect homogeneity in an integrated device can be partially offset by electric field tuning. Using photonic device-coupled implanted nitrogen vacancy (NV) centers in a GaP-on-diamond platform, we demonstrate large field-dependent tuning ranges and partial stabilization of defect emission energies. These results address some of the challenges of chip-scale entanglement generation.

Frequency tuning characteristics of a Q-switched Co:MgF2 laser

NASA Technical Reports Server (NTRS)

Lovold, S.; Moulton, P. F.; Killinger, D. K.; Menyuk, N.

1985-01-01

A tunable Q-switched Co:MgF2 laser has been developed for atmospheric remote sensing applications. Frequency tuning is provided by a quartz etalon and a specially designed three-element birefringent filter covering the whole gain bandwidth of the Co:MgF2 laser. The laser has good temporal and spectral characteristics, with an emission linewidth of approximately 3 GHz (0.1 per cm).

Electrokinetic actuation of liquid metal for reconfigurable radio frequency devices

NASA Astrophysics Data System (ADS)

Gough, Ryan C.

Liquid metals are an attractive material choice for designers wishing to combine the advantages of metals, such as high electrical conductivity, thermal conductivity, and reflectivity, with the inherently dynamic nature of fluids. Liquid metals have been utilized for a wide variety of applications, but their high electrical conductivity, surface smoothness, and linear response makes them especially attractive as tuning elements within reconfigurable radio frequency (RF) devices. The recent introduction of non-toxic liquid metal alloys onto the commercial market has further fueled interest in this versatile material. Early experiments with liquid metal as an RF tuning element have yielded promising results, but have largely depended on externally applied pressure to actuate the liquid metal. For commercial implementation this would necessitate the use of clunky and inefficient micro-pumps, which can require both high voltages and high power consumption. This reliance on hydraulic pumping has been a significant barrier to the incorporation of liquid metal as an RF tuning element in applications outside of a laboratory setting. Here, several electrical actuation techniques are demonstrated that allow for the rapid and repeatable actuation of non-toxic gallium alloys as tuning elements within reconfigurable RF devices. These techniques leverage the naturally high surface tension of liquid metals, as well as the unique electrochemistry of gallium-based alloys, to exercise wide-ranging and high fidelity control over both the metal's shape and position. Furthermore, this control is exercised with voltage and power levels that are each better than an order of magnitude below that achievable with conventional micro-pumps. This control does not require the constant application of actuation signals in order to maintain an actuated state, and can even be 'self-actuated', with the liquid metal supplying its own kinetic energy via the electrochemical conversion of its native oxide layer. Several proof-of-concept devices are designed and tested to demonstrate the effectiveness of these electrical actuation techniques. A pair of tunable slot antennas are presented that achieve frequency reconfigurability through different implementations of liquid metal tuning elements - the first uses liquid metal as a dynamic short-circuit boundary condition for the magnetic current within the resonant aperture, and the second as a variable-length transmission stub that adds and removes reactance from the antenna. The two antennas are tunable across effective bandwidths of 19% and 15%, respectively. In addition, a tunable bandpass filter is demonstrated in which a central liquid-metal resonant element is 'stretched' to lower the passband of the filter by 10% without impacting the insertion loss. Finally, it is demonstrated how liquid metal can be formed into arbitrary shapes at high speeds (approximately 2.5 cm/s) without the need for an external power supply.

Polymer based resonant waveguide grating photonic filter with on-chip thermal tuning

NASA Astrophysics Data System (ADS)

Chaudhuri, Ritesh Ray; Enemuo, Amarachukwu N.; Song, Youngsik; Seo, Sang-Woo

2018-07-01

In this paper, we present the development of a multilayer polymer resonant waveguide grating (RWG)-based optical filter with an integrated microheater for on-chip thermal spectral tuning. RWG optical filter is fabricated using polymer-based materials. Therefore, its integration can be applied to different material platforms. Typical RWG structure is sensitive to back optical reflection from the structures below. To reduce the effect of back reflection from the metal heater and improve the quality of the integrated RWG filter output, an intermediate absorption layer was implemented utilizing an epoxy based carbon coating. This approach effectively suppresses the background noise in the RWG characteristics. The central wavelength of the reported filter was designed around 1550 nm. Experimentally, wavelength tuning of 21.96 nm was achieved for operating temperature range of 81 °C with approximately 150mW power consumption. Based on the layer-by-layer fabrication approach, the presented thermally tunable RWG filter on a chip has potential for use in low cost hybrid communication systems and spectral sensing applications.

PARALLEL MEASUREMENT AND MODELING OF TRANSPORT IN THE DARHT II BEAMLINE ON ETA II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chambers, F W; Raymond, B A; Falabella, S

To successfully tune the DARHT II transport beamline requires the close coupling of a model of the beam transport and the measurement of the beam observables as the beam conditions and magnet settings are varied. For the ETA II experiment using the DARHT II beamline components this was achieved using the SUICIDE (Simple User Interface Connecting to an Integrated Data Environment) data analysis environment and the FITS (Fully Integrated Transport Simulation) model. The SUICIDE environment has direct access to the experimental beam transport data at acquisition and the FITS predictions of the transport for immediate comparison. The FITS model ismore » coupled into the control system where it can read magnet current settings for real time modeling. We find this integrated coupling is essential for model verification and the successful development of a tuning aid for the efficient convergence on a useable tune. We show the real time comparisons of simulation and experiment and explore the successes and limitations of this close coupled approach.« less

Self-Tuning Fully-Connected PID Neural Network System for Distributed Temperature Sensing and Control of Instrument with Multi-Modules.

PubMed

Zhang, Zhen; Ma, Cheng; Zhu, Rong

2016-10-14

High integration of multi-functional instruments raises a critical issue in temperature control that is challenging due to its spatial-temporal complexity. This paper presents a multi-input multi-output (MIMO) self-tuning temperature sensing and control system for efficiently modulating the temperature environment within a multi-module instrument. The smart system ensures that the internal temperature of the instrument converges to a target without the need of a system model, thus making the control robust. The system consists of a fully-connected proportional-integral-derivative (PID) neural network (FCPIDNN) and an on-line self-tuning module. The experimental results show that the presented system can effectively control the internal temperature under various mission scenarios, in particular, it is able to self-reconfigure upon actuator failure. The system provides a new scheme for a complex and time-variant MIMO control system which can be widely applied for the distributed measurement and control of the environment in instruments, integration electronics, and house constructions.

Interactive Visualization Systems and Data Integration Methods for Supporting Discovery in Collections of Scientific Information

DTIC Science & Technology

2011-05-01

iTunes illustrate the difference between the centralized approach of digital library systems and the distributed approach of container file formats...metadata in a container file format. Apple’s iTunes uses a centralized metadata approach and allows users to maintain song metadata in a single...one iTunes library to another the metadata must be copied separately or reentered in the new library. This demonstrates the utility of storing metadata

A Framework for Evaluating Common Operating Environments: Piloting, Lessons Learned, and Opportunities

DTIC Science & Technology

2011-02-01

run a Microsoft OS. Apple iTunes Online sales and distribution of streaming and stored entertain- ment content www.itunes.com Apple provides the...Apple iTunes Online sales and distribu- tion of streaming and stored entertainment con- tent PodCast Creator Podcast Creator provides integrated...Commercial examples of software system COEs include Cisco WebEx, Microsoft NetMeet- CMU/SEI-2010-SR-025 | 16 ing, and Apple iTunes . Example Problem Space

Hardware platforms for MEMS gyroscope tuning based on evolutionary computation using open-loop and closed -loop frequency response

NASA Technical Reports Server (NTRS)

Keymeulen, Didier; Ferguson, Michael I.; Fink, Wolfgang; Oks, Boris; Peay, Chris; Terrile, Richard; Cheng, Yen; Kim, Dennis; MacDonald, Eric; Foor, David

2005-01-01

We propose a tuning method for MEMS gyroscopes based on evolutionary computation to efficiently increase the sensitivity of MEMS gyroscopes through tuning. The tuning method was tested for the second generation JPL/Boeing Post-resonator MEMS gyroscope using the measurement of the frequency response of the MEMS device in open-loop operation. We also report on the development of a hardware platform for integrated tuning and closed loop operation of MEMS gyroscopes. The control of this device is implemented through a digital design on a Field Programmable Gate Array (FPGA). The hardware platform easily transitions to an embedded solution that allows for the miniaturization of the system to a single chip.

Amplifier Module for 260-GHz Band Using Quartz Waveguide Transitions

NASA Technical Reports Server (NTRS)

Padmanabhan, Sharmila; Fung, King Man; Kangaslahti, Pekka P.; Peralta, Alejandro; Soria, Mary M.; Pukala, David M.; Sin, Seth; Samoska, Lorene A.; Sarkozy, Stephen; Lai, Richard

2012-01-01

Packaging of MMIC LNA (monolithic microwave integrated circuit low-noise amplifier) chips at frequencies over 200 GHz has always been problematic due to the high loss in the transition between the MMIC chip and the waveguide medium in which the chip will typically be used. In addition, above 200 GHz, wire-bond inductance between the LNA and the waveguide can severely limit the RF matching and bandwidth of the final waveguide amplifier module. This work resulted in the development of a low-loss quartz waveguide transition that includes a capacitive transmission line between the MMIC and the waveguide probe element. This capacitive transmission line tunes out the wirebond inductance (where the wire-bond is required to bond between the MMIC and the probe element). This inductance can severely limit the RF matching and bandwidth of the final waveguide amplifier module. The amplifier module consists of a quartz E-plane waveguide probe transition, a short capacitive tuning element, a short wire-bond to the MMIC, and the MMIC LNA. The output structure is similar, with a short wire-bond at the output of the MMIC, a quartz E-plane waveguide probe transition, and the output waveguide. The quartz probe element is made of 3-mil quartz, which is the thinnest commercially available material. The waveguide band used is WR4, from 170 to 260 GHz. This new transition and block design is an improvement over prior art because it provides for better RF matching, and will likely yield lower loss and better noise figure. The development of high-performance, low-noise amplifiers in the 180-to- 700-GHz range has applications for future earth science and planetary instruments with low power and volume, and astrophysics array instruments for molecular spectroscopy. This frequency band, while suitable for homeland security and commercial applications (such as millimeter-wave imaging, hidden weapons detection, crowd scanning, airport security, and communications), also has applications to future NASA missions. The Global Atmospheric Composition Mission (GACM) in the NRC Decadel Survey will need low-noise amplifiers with extremely low noise temperatures, either at room temperature or for cryogenic applications, for atmospheric remote sensing.

Miniature infrared hyperspectral imaging sensor for airborne applications

NASA Astrophysics Data System (ADS)

Hinnrichs, Michele; Hinnrichs, Bradford; McCutchen, Earl

2017-05-01

Pacific Advanced Technology (PAT) has developed an infrared hyperspectral camera, both MWIR and LWIR, small enough to serve as a payload on a miniature unmanned aerial vehicles. The optical system has been integrated into the cold-shield of the sensor enabling the small size and weight of the sensor. This new and innovative approach to infrared hyperspectral imaging spectrometer uses micro-optics and will be explained in this paper. The micro-optics are made up of an area array of diffractive optical elements where each element is tuned to image a different spectral region on a common focal plane array. The lenslet array is embedded in the cold-shield of the sensor and actuated with a miniature piezo-electric motor. This approach enables rapid infrared spectral imaging with multiple spectral images collected and processed simultaneously each frame of the camera. This paper will present our optical mechanical design approach which results in an infrared hyper-spectral imaging system that is small enough for a payload on a mini-UAV or commercial quadcopter. The diffractive optical elements used in the lenslet array are blazed gratings where each lenslet is tuned for a different spectral bandpass. The lenslets are configured in an area array placed a few millimeters above the focal plane and embedded in the cold-shield to reduce the background signal normally associated with the optics. We have developed various systems using a different number of lenslets in the area array. Depending on the size of the focal plane and the diameter of the lenslet array will determine the spatial resolution. A 2 x 2 lenslet array will image four different spectral images of the scene each frame and when coupled with a 512 x 512 focal plane array will give spatial resolution of 256 x 256 pixel each spectral image. Another system that we developed uses a 4 x 4 lenslet array on a 1024 x 1024 pixel element focal plane array which gives 16 spectral images of 256 x 256 pixel resolution each frame.

Infrared hyperspectral imaging miniaturized for UAV applications

NASA Astrophysics Data System (ADS)

Hinnrichs, Michele; Hinnrichs, Bradford; McCutchen, Earl

2017-02-01

Pacific Advanced Technology (PAT) has developed an infrared hyperspectral camera, both MWIR and LWIR, small enough to serve as a payload on a miniature unmanned aerial vehicles. The optical system has been integrated into the cold-shield of the sensor enabling the small size and weight of the sensor. This new and innovative approach to infrared hyperspectral imaging spectrometer uses micro-optics and will be explained in this paper. The micro-optics are made up of an area array of diffractive optical elements where each element is tuned to image a different spectral region on a common focal plane array. The lenslet array is embedded in the cold-shield of the sensor and actuated with a miniature piezo-electric motor. This approach enables rapid infrared spectral imaging with multiple spectral images collected and processed simultaneously each frame of the camera. This paper will present our optical mechanical design approach which results in an infrared hyper-spectral imaging system that is small enough for a payload on a mini-UAV or commercial quadcopter. Also, an example of how this technology can easily be used to quantify a hydrocarbon gas leak's volume and mass flowrates. The diffractive optical elements used in the lenslet array are blazed gratings where each lenslet is tuned for a different spectral bandpass. The lenslets are configured in an area array placed a few millimeters above the focal plane and embedded in the cold-shield to reduce the background signal normally associated with the optics. We have developed various systems using a different number of lenslets in the area array. Depending on the size of the focal plane and the diameter of the lenslet array will determine the spatial resolution. A 2 x 2 lenslet array will image four different spectral images of the scene each frame and when coupled with a 512 x 512 focal plane array will give spatial resolution of 256 x 256 pixel each spectral image. Another system that we developed uses a 4 x 4 lenslet array on a 1024 x 1024 pixel element focal plane array which gives 16 spectral images of 256 x 256 pixel resolution each frame.

McMillan Lens in a System with Space Charge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lobach, I.; Nagaitsev, S.; Stern, E.

Space charge (SC) in a circulating beam in a ring produces both betatron tune shift and betatron tune spread. These effects make some particles move on to a machine resonance and become unstable. Linear elements of beam optics cannot reduce the tune spread induced by SC because of its intrinsic nonlinear nature. We investigate the possibility to mitigate it by a thin McMillan lens providing a nonlinear axially symmetric kick, which is qualitatively opposite to the accumulated kick by SC. Experimentally, the proposed concept can be tested in Fermilab's IOTA ring. A thin McMillan lens can be implemented by amore » short (70 cm) insertion of an electron beam with specifically chosen density distribution in transverse directions. In this article, to see if McMillan lenses reduce the tune spread induced by SC, we make several simulations with particle tracking code Synergia. We choose such beam and lattice parameters that tune spread is roughly 0.5 and a beam instability due to the half-integer resonance 0.5 is observed. Then, we try to reduce emittance growth by shifting betatron tunes by adjusting quadrupoles and reducing the tune spread by McMillan lenses.« less

Nonlinear analysis of a family of LC tuned inverters. [dc to square wave circuits for power conditioning

NASA Technical Reports Server (NTRS)

Lee, F. C. Y.; Wilson, T. G.

1974-01-01

A family of four dc-to-square-wave LC tuned inverters are analyzed using singular point. Limit cycles and waveshape characteristics are given for three modes of oscillation: quasi-harmonic, relaxation, and discontinuous. An inverter in which the avalanche breakdown of the transistor emitter-to-base junction occurs is discussed and the starting characteristics of this family of inverters are presented. The LC tuned inverters are shown to belong to a family of inverters with a common equivalent circuit consisting of only three 'series' elements: a five-segment piecewise-linear current-controlled resistor, linear inductor, and linear capacitor.

Mechanisms of spectral and temporal integration in the mustached bat inferior colliculus

PubMed Central

Wenstrup, Jeffrey James; Nataraj, Kiran; Sanchez, Jason Tait

2012-01-01

This review describes mechanisms and circuitry underlying combination-sensitive response properties in the auditory brainstem and midbrain. Combination-sensitive neurons, performing a type of auditory spectro-temporal integration, respond to specific, properly timed combinations of spectral elements in vocal signals and other acoustic stimuli. While these neurons are known to occur in the auditory forebrain of many vertebrate species, the work described here establishes their origin in the auditory brainstem and midbrain. Focusing on the mustached bat, we review several major findings: (1) Combination-sensitive responses involve facilitatory interactions, inhibitory interactions, or both when activated by distinct spectral elements in complex sounds. (2) Combination-sensitive responses are created in distinct stages: inhibition arises mainly in lateral lemniscal nuclei of the auditory brainstem, while facilitation arises in the inferior colliculus (IC) of the midbrain. (3) Spectral integration underlying combination-sensitive responses requires a low-frequency input tuned well below a neuron's characteristic frequency (ChF). Low-ChF neurons in the auditory brainstem project to high-ChF regions in brainstem or IC to create combination sensitivity. (4) At their sites of origin, both facilitatory and inhibitory combination-sensitive interactions depend on glycinergic inputs and are eliminated by glycine receptor blockade. Surprisingly, facilitatory interactions in IC depend almost exclusively on glycinergic inputs and are largely independent of glutamatergic and GABAergic inputs. (5) The medial nucleus of the trapezoid body (MNTB), the lateral lemniscal nuclei, and the IC play critical roles in creating combination-sensitive responses. We propose that these mechanisms, based on work in the mustached bat, apply to a broad range of mammals and other vertebrates that depend on temporally sensitive integration of information across the audible spectrum. PMID:23109917

Strongly-Refractive One-Dimensional Photonic Crystal Prisms

NASA Technical Reports Server (NTRS)

Ting, David Z. (Inventor)

2004-01-01

One-dimensional (1D) photonic crystal prisms can separate a beam of polychromatic electromagnetic waves into constituent wavelength components and can utilize unconventional refraction properties for wavelength dispersion over significant portions of an entire photonic band rather than just near the band edges outside the photonic band gaps. Using a ID photonic crystal simplifies the design and fabrication process and allows the use of larger feature sizes. The prism geometry broadens the useful wavelength range, enables better optical transmission, and exhibits angular dependence on wavelength with reduced non-linearity. The properties of the 1 D photonic crystal prism can be tuned by varying design parameters such as incidence angle, exit surface angle, and layer widths. The ID photonic crystal prism can be fabricated in a planar process, and can be used as optical integrated circuit elements.

Micromachined Millimeter- and Submillimeter-Wave SIS Heterodyne Receivers for Remote Sensing

NASA Technical Reports Server (NTRS)

Hu, Qing

1998-01-01

A heterodyne mixer with a micromachined horn antenna and a superconductor -insulator-superconductor (SIS) tunnel junction as mixing element is tested in the W-band (75-115 GHz) frequency range. Micromachined integrated horn antennas consist of a dipole antenna suspended on a thin Si3N4 dielectric membrane inside a pyramidal cavity etched in silicon. The mixer performance is optimized by using a backing plane behind the dipole antenna to tune out the capacitance of the tunnel junction. The lowest receiver noise temperature of 30+/-3 K without any correction) is measured at 106 GHz with a 3-dB bandwidth of 8 GHz. This sensitivity is comparable to the state-of-the-art waveguide and quasi-optical SIS receivers, showing the potential use of micromachined horn antennas in imaging arrays.

Educational Tool for Optimal Controller Tuning Using Evolutionary Strategies

ERIC Educational Resources Information Center

Carmona Morales, D.; Jimenez-Hornero, J. E.; Vazquez, F.; Morilla, F.

2012-01-01

In this paper, an optimal tuning tool is presented for control structures based on multivariable proportional-integral-derivative (PID) control, using genetic algorithms as an alternative to traditional optimization algorithms. From an educational point of view, this tool provides students with the necessary means to consolidate their knowledge on…

SKYWARD: the next generation airborne infrared search and track

NASA Astrophysics Data System (ADS)

Fortunato, L.; Colombi, G.; Ondini, A.; Quaranta, C.; Giunti, C.; Sozzi, B.; Balzarotti, G.

2016-05-01

Infrared Search and Track systems are an essential element of the modern and future combat aircrafts. Passive automatic search, detection and tracking functions, are key points for silent operations or jammed tactical scenarios. SKYWARD represents the latest evolution of IRST technology in which high quality electro-optical components, advanced algorithms, efficient hardware and software solutions are harmonically integrated to provide high-end affordable performances. Additionally, the reduction of critical opto-mechanical elements optimises weight and volume and increases the overall reliability. Multiple operative modes dedicated to different situations are available; many options can be selected among multiple or single target tracking, for surveillance or engagement, and imaging, for landing or navigation aid, assuring the maximum system flexibility. The high quality 2D-IR sensor is exploited by multiple parallel processing chains, based on linear and non-linear techniques, to extract the possible targets from background, in different conditions, with false alarm rate control. A widely tested track processor manages a large amount of candidate targets simultaneously and allows discriminating real targets from noise whilst operating with low target to background contrasts. The capability of providing reliable passive range estimation is an additional qualifying element of the system. Particular care has been dedicated to the detector non-uniformities, a possible limiting factor for distant targets detection, as well as to the design of the electro-optics for a harsh airborne environment. The system can be configured for LWIR or MWIR waveband according to the customer operational requirements. An embedded data recorder saves all the necessary images and data for mission debriefing, particularly useful during inflight system integration and tuning.

The chaotic dynamical aperture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, S.Y.; Tepikian, S.

1985-10-01

Nonlinear magnetic forces become more important for particles in the modern large accelerators. These nonlinear elements are introduced either intentionally to control beam dynamics or by uncontrollable random errors. Equations of motion in the nonlinear Hamiltonian are usually non-integrable. Because of the nonlinear part of the Hamiltonian, the tune diagram of accelerators is a jungle. Nonlinear magnet multipoles are important in keeping the accelerator operation point in the safe quarter of the hostile jungle of resonant tunes. Indeed, all the modern accelerator design have taken advantages of nonlinear mechanics. On the other hand, the effect of the uncontrollable random multipolesmore » should be evaluated carefully. A powerful method of studying the effect of these nonlinear multipoles is using a particle tracking calculation, where a group of test particles are tracing through these magnetic multipoles in the accelerator hundreds to millions of turns in order to test the dynamical aperture of the machine. These methods are extremely useful in the design of a large accelerator such as SSC, LEP, HERA and RHIC. These calculations unfortunately take tremendous amount of computing time. In this paper, we try to apply the existing method in the nonlinear dynamics to study the possible alternative solution. When the Hamiltonian motion becomes chaotic, the tune of the machine becomes undefined. The aperture related to the chaotic orbit can be identified as chaotic dynamical aperture. We review the method of determining chaotic orbit and apply the method to nonlinear problems in accelerator physics. We then discuss the scaling properties and effect of random sextupoles.« less

Binocular disparity tuning and visual-vestibular congruency of multisensory neurons in macaque parietal cortex

PubMed Central

Yang, Yun; Liu, Sheng; Chowdhury, Syed A.; DeAngelis, Gregory C.; Angelaki, Dora E.

2012-01-01

Many neurons in the dorsal medial superior temporal (MSTd) and ventral intraparietal (VIP) areas of the macaque brain are multisensory, responding to both optic flow and vestibular cues to self-motion. The heading tuning of visual and vestibular responses can be either congruent or opposite, but only congruent cells have been implicated in cue integration for heading perception. Because of the geometric properties of motion parallax, however, both congruent and opposite cells could be involved in coding self-motion when observers fixate a world-fixed target during translation, if congruent cells prefer near disparities and opposite cells prefer far disparities. We characterized the binocular disparity selectivity and heading tuning of MSTd and VIP cells using random-dot stimuli. Most (70%) MSTd neurons were disparity-selective with monotonic tuning, and there was no consistent relationship between depth preference and congruency of visual and vestibular heading tuning. One-third of disparity-selective MSTd cells reversed their depth preference for opposite directions of motion (direction-dependent disparity tuning, DDD), but most of these cells were unisensory with no tuning for vestibular stimuli. Inconsistent with previous reports, the direction preferences of most DDD neurons do not reverse with disparity. By comparison to MSTd, VIP contains fewer disparity-selective neurons (41%) and very few DDD cells. On average, VIP neurons also preferred higher speeds and nearer disparities than MSTd cells. Our findings are inconsistent with the hypothesis that visual/vestibular congruency is linked to depth preference, and also suggest that DDD cells are not involved in multisensory integration for heading perception. PMID:22159105

Localized direction selective responses in the dendrites of visual interneurons of the fly

PubMed Central

2010-01-01

Background The various tasks of visual systems, including course control, collision avoidance and the detection of small objects, require at the neuronal level the dendritic integration and subsequent processing of many spatially distributed visual motion inputs. While much is known about the pooled output in these systems, as in the medial superior temporal cortex of monkeys or in the lobula plate of the insect visual system, the motion tuning of the elements that provide the input has yet received little attention. In order to visualize the motion tuning of these inputs we examined the dendritic activation patterns of neurons that are selective for the characteristic patterns of wide-field motion, the lobula-plate tangential cells (LPTCs) of the blowfly. These neurons are known to sample direction-selective motion information from large parts of the visual field and combine these signals into axonal and dendro-dendritic outputs. Results Fluorescence imaging of intracellular calcium concentration allowed us to take a direct look at the local dendritic activity and the resulting local preferred directions in LPTC dendrites during activation by wide-field motion in different directions. These 'calcium response fields' resembled a retinotopic dendritic map of local preferred directions in the receptive field, the layout of which is a distinguishing feature of different LPTCs. Conclusions Our study reveals how neurons acquire selectivity for distinct visual motion patterns by dendritic integration of the local inputs with different preferred directions. With their spatial layout of directional responses, the dendrites of the LPTCs we investigated thus served as matched filters for wide-field motion patterns. PMID:20384983

Base excitation testing system using spring elements to pivotally mount wind turbine blades

DOEpatents

Cotrell, Jason; Hughes, Scott; Butterfield, Sandy; Lambert, Scott

2013-12-10

A system (1100) for fatigue testing wind turbine blades (1102) through forced or resonant excitation of the base (1104) of a blade (1102). The system (1100) includes a test stand (1112) and a restoring spring assembly (1120) mounted on the test stand (1112). The restoring spring assembly (1120) includes a primary spring element (1124) that extends outward from the test stand (1112) to a blade mounting plate (1130) configured to receive a base (1104) of blade (1102). During fatigue testing, a supported base (1104) of a blad (1102) may be pivotally mounted to the test stand (1112) via the restoring spring assembly (1120). The system (1100) may include an excitation input assembly (1140) that is interconnected with the blade mouting plate (1130) to selectively apply flapwise, edgewise, and/or pitch excitation forces. The restoring spring assemply (1120) may include at least one tuning spring member (1127) positioned adjacent to the primary spring element (1124) used to tune the spring constant or stiffness of the primary spring element (1124) in one of the excitation directions.

Integrated optoelectronic oscillator.

PubMed

Tang, Jian; Hao, Tengfei; Li, Wei; Domenech, David; Baños, Rocio; Muñoz, Pascual; Zhu, Ninghua; Capmany, José; Li, Ming

2018-04-30

With the rapid development of the modern communication systems, radar and wireless services, microwave signal with high-frequency, high-spectral-purity and frequency tunability as well as microwave generator with light weight, compact size, power-efficient and low cost are increasingly demanded. Integrated microwave photonics (IMWP) is regarded as a prospective way to meet these demands by hybridizing the microwave circuits and the photonics circuits on chip. In this article, we propose and experimentally demonstrate an integrated optoelectronic oscillator (IOEO). All of the devices needed in the optoelectronic oscillation loop circuit are monolithically integrated on chip within size of 5×6cm 2 . By tuning the injection current to 44 mA, the output frequency of the proposed IOEO is located at 7.30 GHz with phase noise value of -91 dBc/Hz@1MHz. When the injection current is increased to 65 mA, the output frequency can be changed to 8.87 GHz with phase noise value of -92 dBc/Hz@1MHz. Both of the oscillation frequency can be slightly tuned within 20 MHz around the center oscillation frequency by tuning the injection current. The method about improving the performance of IOEO is carefully discussed at the end of in this article.

Generation of optical vortices in an integrated optical circuit

NASA Astrophysics Data System (ADS)

Tudor, Rebeca; Kusko, Mihai; Kusko, Cristian

2017-09-01

In this work, the generation of optical vortices in an optical integrated circuit is numerically demonstrated. The optical vortices with topological charge m = ±1 are obtained by the coherent superposition of the first order modes present in a waveguide with a rectangular cross section, where the phase delay between these two propagating modes is Δφ = ±π/2. The optical integrated circuit consists of an input waveguide continued with a y-splitter. The left and the right arms of the splitter form two coupling regions K1 and K2 with a multimode output waveguide. In each coupling region, the fundamental modes present in the arms of the splitter are selectively coupled into the output waveguide horizontal and vertical first order modes, respectively. We showed by employing the beam propagation method simulations that the fine tuning of the geometrical parameters of the optical circuit makes possible the generation of optical vortices in both transverse electric (TE) and transverse magnetic (TM) modes. Also, we demonstrated that by placing a thermo-optical element on one of the y-splitter arms, it is possible to switch the topological charge of the generated vortex from m = 1 to m = -1.

Experimental and analytical studies on multiple tuned mass dampers for seismic protection of porcelain electrical equipment

NASA Astrophysics Data System (ADS)

Bai, Wen; Dai, Junwu; Zhou, Huimeng; Yang, Yongqiang; Ning, Xiaoqing

2017-10-01

Porcelain electrical equipment (PEE), such as current transformers, is critical to power supply systems, but its seismic performance during past earthquakes has not been satisfactory. This paper studies the seismic performance of two typical types of PEE and proposes a damping method for PEE based on multiple tuned mass dampers (MTMD). An MTMD damping device involving three mass units, named a triple tuned mass damper (TTMD), is designed and manufactured. Through shake table tests and finite element analysis, the dynamic characteristics of the PEE are studied and the effectiveness of the MTMD damping method is verified. The adverse influence of MTMD redundant mass to damping efficiency is studied and relevant equations are derived. MTMD robustness is verified through adjusting TTMD control frequencies. The damping effectiveness of TTMD, when the peak ground acceleration far exceeds the design value, is studied. Both shake table tests and finite element analysis indicate that MTMD is effective and robust in attenuating PEE seismic responses. TTMD remains effective when the PGA far exceeds the design value and when control deviations are considered.

Dye laser traveling wave amplifier

NASA Technical Reports Server (NTRS)

Davidson, F.; Hohman, J.

1985-01-01

Injection locking was applied to a cavity-dumped coaxial flashlamp pumped dye laser in an effort to obtain nanosecond duration pulses which have both high energy and narrow-linewidth. In the absence of an injected laser pulse, the cavity-dumped dye laser was capable of generating high energy (approx. 60mJ) nanosecond duration output pulses. These pulses, however, had a fixed center wavelength and were extremely broadband (approx. 6nm FWHM). Experimental investigations were performed to determine if the spectral properties of these outputs could be improved through the use of injection-locking techniques. A parametric study to determine the specific conditions under which the laser could be injection-locked was also carried out. Significant linewidth reduction to 0.0015nm) of the outputs was obtained through injection-locking but only at wavelengths near the peak lasing wavelength of the dye. It was found, however; that by inserting weakly dispersive tuning elements in the laser cavity, these narrow-linewidth outputs could be obtained over a wide (24nm) tuning range. Since the tuning elements had low insertion losses, the tunability of the output was obtained without sacrificing output pulse energy.

Remote focusing in confocal microscopy by means of a modified Alvarez lens.

PubMed

Bawart, M; Jesacher, A; Bernet, S; Ritsch-Marte, M

2018-06-22

Alvarez lenses are actuated lens-pairs which allow one to tune the optical power by mechanical displacement of subelements. Here, we show that a recently realized modified Alvarez lens design which does not require mechanical actuation can be integrated into a confocal microscope. Instead of mechanically moving them, the sublenses are imaged onto each other in a 4f-configuration, where the lateral image shift leading to a change in optical power is created by a galvo-mirror. The avoidance of mechanical lens shifts leads to a large speed gain for axial (and hence also 3D) image scans compared to classical Alvarez lenses. We demonstrate that the suggested operation principle is compatible with confocal microscopy. In order to optimize the system, we have drawn advantage of the flexibility a liquid-crystal spatial light modulator offers for the implementation. For given specifications, dedicated diffractive optical elements or freeform elements can be used in combination with resonant galvo-scanners or acousto-optic beam deflectors, to achieve even faster z-scans than reported here, reaching video rate. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

Nanoboomerang-based inverse metasurfaces—A promising path towards ultrathin photonic devices for transmission operation

NASA Astrophysics Data System (ADS)

Zeisberger, Matthias; Schneidewind, Henrik; Huebner, Uwe; Popp, Juergen; Schmidt, Markus A.

2017-03-01

Metasurfaces have revolutionized photonics due to their ability to shape phase fronts as requested and to tune beam directionality using nanoscale metallic or dielectric scatterers. Here we reveal inverse metasurfaces showing superior properties compared to their positive counterparts if transmission mode operation is considered. The key advantage of such slot-type metasurfaces is the strong reduction of light in the parallel-polarization state, making the crossed-polarization, being essential for metasurface operation, dominant and highly visible. In the experiment, we show an up to four times improvement in polarization extinction for the individual metasurface element geometry consisting of deep subwavelength nanoboomerangs with feature sizes of the order of 100 nm. As confirmed by simulations, strong plasmonic hybridization yields two spectrally separated plasmonic resonances, ultimately allowing for the desired phase and scattering engineering in transmission. Due to the design flexibility of inverse metasurfaces, a large number of highly integrated ultra-flat photonic elements can be envisioned, examples of which include monolithic lenses for telecommunications and spectroscopy, beam shaper or generator for particle trapping or acceleration or sophisticated polarization control for microscopy.

Design and simulation of programmable relational optoelectronic time-pulse coded processors as base elements for sorting neural networks

NASA Astrophysics Data System (ADS)

Krasilenko, Vladimir G.; Nikolsky, Alexander I.; Lazarev, Alexander A.; Lazareva, Maria V.

2010-05-01

In the paper we show that the biologically motivated conception of time-pulse encoding usage gives a set of advantages (single methodological basis, universality, tuning simplicity, learning and programming et al) at creation and design of sensor systems with parallel input-output and processing for 2D structures hybrid and next generations neuro-fuzzy neurocomputers. We show design principles of programmable relational optoelectronic time-pulse encoded processors on the base of continuous logic, order logic and temporal waves processes. We consider a structure that execute analog signal extraction, analog and time-pulse coded variables sorting. We offer optoelectronic realization of such base relational order logic element, that consists of time-pulse coded photoconverters (pulse-width and pulse-phase modulators) with direct and complementary outputs, sorting network on logical elements and programmable commutation blocks. We make technical parameters estimations of devices and processors on such base elements by simulation and experimental research: optical input signals power 0.2 - 20 uW, processing time 1 - 10 us, supply voltage 1 - 3 V, consumption power 10 - 100 uW, extended functional possibilities, learning possibilities. We discuss some aspects of possible rules and principles of learning and programmable tuning on required function, relational operation and realization of hardware blocks for modifications of such processors. We show that it is possible to create sorting machines, neural networks and hybrid data-processing systems with untraditional numerical systems and pictures operands on the basis of such quasiuniversal hardware simple blocks with flexible programmable tuning.

Thermally controlled coupling of a rolled-up microtube integrated with a waveguide on a silicon electronic-photonic integrated circuit.

PubMed

Zhong, Qiuhang; Tian, Zhaobing; Veerasubramanian, Venkat; Dastjerdi, M Hadi Tavakoli; Mi, Zetian; Plant, David V

2014-05-01

We report on the first experimental demonstration of the thermal control of coupling strength between a rolled-up microtube and a waveguide on a silicon electronic-photonic integrated circuit. The microtubes are fabricated by selectively releasing a coherently strained GaAs/InGaAs heterostructure bilayer. The fabricated microtubes are then integrated with silicon waveguides using an abruptly tapered fiber probe. By tuning the gap between the microtube and the waveguide using localized heaters, the microtube-waveguide evanescent coupling is effectively controlled. With heating, the extinction ratio of a microtube whispering-gallery mode changes over an 18 dB range, while the resonant wavelength remains approximately unchanged. Utilizing this dynamic thermal tuning effect, we realize coupling modulation of the microtube integrated with the silicon waveguide at 2 kHz with a heater voltage swing of 0-6 V.

80-GHz MMIC HEMT Voltage-Controlled Oscillator

NASA Technical Reports Server (NTRS)

Samoska, Lorene; Radisic, Vesna; Micovic, Miro; Hu, Ming; Janke, Paul; Ngo, Catherine; Nguyen, Loi

2003-01-01

A voltage-controlled oscillator (VCO) that operates in the frequency range from 77.5 to 83.5 GHz has been constructed in the form of a monolithic microwave integrated circuit (MMIC) that includes high-electron-mobility transistors (HEMTs). This circuit is a prototype of electronically tunable signal sources in the 75-to-110-GHz range, needed for communication, imaging, and automotive radar applications, among others. This oscillator (see Figure 1) includes two AlInAs/GaInAs/InP HEMTs. One HEMT serves mainly as an oscillator gain element. The other HEMT serves mainly as a varactor for controlling the frequency: the frequency-control element is its gate-to-source capacitance, which is varied by changing its gate supply voltage. The gain HEMT is biased for class-A operation (meaning that current is conducted throughout the oscillation cycle). Grounded coplanar waveguides are used as impedance-matching transmission lines, the input and output matching being chosen to sustain oscillation and maximize output power. Air bridges are placed at discontinuities to suppress undesired slot electromagnetic modes. A high density of vias is necessary for suppressing a parallel-plate electromagnetic mode that is undesired because it can propagate energy into the MMIC substrate. Previous attempts at constructing HEMT-based oscillators yielded circuits with relatively low levels of output power and narrow tuning ranges. For example, one HEMT VCO reported in the literature had an output power of 7 dBm (.5 mW) and a tuning range 2-GHz wide centered approximately at a nominal frequency of 77 GHz. In contrast, as shown in Figure 2, the present MMIC HEMT VCO puts out a power of 12.5 dBm (.18 mW) or more over the 6-GHz-wide frequency range from 77.5 to 83.5 GHz

First-Row Transition Metal Doping in Calcium Phosphate Bioceramics: A Detailed Crystallographic Study

PubMed Central

Renaudin, Guillaume; Gomes, Sandrine; Nedelec, Jean-Marie

2017-01-01

Doped calcium phosphate bioceramics are promising materials for bone repair surgery because of their chemical resemblance to the mineral constituent of bone. Among these materials, BCP samples composed of hydroxyapatite (Ca10(PO4)6(OH)2) and β-TCP (Ca3(PO4)2) present a mineral analogy with the nano-multi-substituted hydroxyapatite bio-mineral part of bones. At the same time, doping can be used to tune the biological properties of these ceramics. This paper presents a general overview of the doping mechanisms of BCP samples using cations from the first-row transition metals (from manganese to zinc), with respect to the applied sintering temperature. The results enable the preparation of doped synthetic BCP that can be used to tailor biological properties, in particular by tuning the release amounts upon interaction with biological fluids. Intermediate sintering temperatures stabilize the doping elements in the more soluble β-TCP phase, which favors quick and easy release upon integration in the biological environment, whereas higher sintering temperatures locate the doping elements in the weakly soluble HAp phase, enabling a slow and continuous supply of the bio-inspired properties. An interstitial doping mechanism in the HAp hexagonal channel is observed for the six investigated cations (Mn2+, Fe3+, Co2+, Ni2+, Cu2+ and Zn2+) with specific characteristics involving a shift away from the center of the hexagonal channel (Fe3+, Co2+), cationic oxidation (Mn3+, Co3+), and also cationic reduction (Cu+). The complete crystallochemical study highlights a complex HAp doping mechanism, mainly realized by an interstitial process combined with calcium substitution for the larger cations of the series leading to potentially calcium deficient HAp. PMID:28772452

Evolutionarily Conserved, Growth Plate Zone-Specific Regulation of the Matrilin-1 Promoter: L-Sox5/Sox6 and Nfi Factors Bound near TATA Finely Tune Activation by Sox9 ▿

PubMed Central

Nagy, Andrea; Kénesi, Erzsébet; Rentsendorj, Otgonchimeg; Molnár, Annamária; Szénási, Tibor; Sinkó, Ildikó; Zvara, Ágnes; Thottathil Oommen, Sajit; Barta, Endre; Puskás, László G.; Lefebvre, Veronique; Kiss, Ibolya

2011-01-01

To help uncover the mechanisms underlying the staggered expression of cartilage-specific genes in the growth plate, we dissected the transcriptional mechanisms driving expression of the matrilin-1 gene (Matn1). We show that a unique assembly of evolutionarily conserved cis-acting elements in the Matn1 proximal promoter restricts expression to the proliferative and prehypertrophic zones of the growth plate. These elements functionally interact with distal elements and likewise are capable of restricting the domain of activity of a pancartilaginous Col2a1 enhancer. The proximal elements include a Pe1 element binding the chondrogenic L-Sox5, Sox6, and Sox9 proteins, a SI element binding Nfi proteins, and an initiator Ine element binding the Sox trio and other factors. Sox9 binding to Pe1 is indispensable for functional interaction with the distal promoter. Binding of L-Sox5/Sox6 to Ine and Nfib to SI modulates Sox9 transactivation in a protein dose-dependent manner, possibly to enhance Sox9 activity in early stages of chondrogenesis and repress it at later stages. Hence, our data suggest a novel model whereby Sox and Nfi proteins bind to conserved Matn1 proximal elements and functionally interact with each other to finely tune gene expression in specific zones of the cartilage growth plate. PMID:21173167

RF tuning element

NASA Technical Reports Server (NTRS)

McGrath, William R. (Inventor); Lubecke, Victor M. (Inventor)

1992-01-01

A device for tuning a circuit includes a substrate, a transmission line on the substrate that includes first and second conductors coupled to a circuit to be tuned, and a movable short-circuit for varying the impedance the transmission line presents to the circuit to be tuned. The movable short-circuit includes a dielectric layer disposed atop the transmission line and a distributed shorting element in the form of a conductive member that is configured to be slid along at least a portion of the transmission line atop the dielectric layer. The conductive member is configured to span the first and second conductors of the transmission line and to define at least a first opening that spans the two conductors so that the conductive member includes first and second sections separated by the first opening. The first and second sections of the conductive member combine with the first and second conductors of the transmission line to form first and second low impedance sections of transmission line, and the opening combines with the first and second conductors of the transmission line and the dielectric layer to form a first high impedance section of transmission line intermediate the first and second low impedance sections. Each of the first low impedance section and the first high impedance section have a length along the transmission line of approximately one-quarter wavelength, thus providing a periodic variation of transmission line impedance. That enhances reflection of rf power.

Chaotic dynamical aperture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, S.Y.; Tepikian, S.

1985-01-01

Nonlinear magnetic forces become more important for particles in the modern large accelerators. These nonlinear elements are introduced either intentionally to control beam dynamics or by uncontrollable random errors. Equations of motion in the nonlinear Hamiltonian are usually non-integrable. Because of the nonlinear part of the Hamiltonian, the tune diagram of accelerators is a jungle. Nonlinear magnet multipoles are important in keeping the accelerator operation point in the safe quarter of the hostile jungle of resonant tunes. Indeed, all the modern accelerator designs have taken advantages of nonlinear mechanics. On the other hand, the effect of the uncontrollable random multipolesmore » should be evaluated carefully. A powerful method of studying the effect of these nonlinear multipoles is using a particle tracking calculation, where a group of test particles are tracing through these magnetic multipoles in the accelerator hundreds to millions of turns in order to test the dynamical aperture of the machine. These methods are extremely useful in the design of a large accelerator such as SSC, LEP, HERA and RHIC. These calculations unfortunately take a tremendous amount of computing time. In this review the method of determining chaotic orbit and applying the method to nonlinear problems in accelerator physics is discussed. We then discuss the scaling properties and effect of random sextupoles.« less

Optical cross-talk and surface characterization of SERS nanoimaging bundle substrates

NASA Astrophysics Data System (ADS)

Kiser, John B.; Cullum, Brian M.

2010-04-01

Due to the narrow vibrational bandwidths and unique molecular fingerprints, Raman spectroscopy can be an information rich transduction technique for chemical imaging. Dynamic systems are often difficult to measure using spontaneous Raman due to the relatively weak scattering cross-sections. Using a Raman enhancement mechanism such as surface enhanced Raman scattering (SERS), exposure times can be reduced to a reasonable level for dynamic imaging, due to the increased Raman signal intensity. This paper will discuss the development of a novel SERS substrate, fabricated on the tips of fiber-optic imaging bundles, which can be integrated into a multispectral imaging system for non-scanning chemical imaging. These substrates are fabricated by mechanically tapering a polished fiber optic imaging bundle consisting of 30,000 individual elements; producing 100-nm or smaller diameter core elements on the distal tip. Chemical etching with hydrofluoric acid creates uniform cladding spikes onto which a SERS active metal is vacuum deposited, forming the SERS active surface. By varying the size of the silver islands deposited on the cladding peaks active, surface plasmons can be tuned to various excitation frequencies. The surface of these tapered fiber optic probes will be evaluated by analysis of the SERS signal, location and shape of the active surface plasmons. The cross talk between the fiber elements will also be evaluated.

Continuous Firefly Algorithm for Optimal Tuning of Pid Controller in Avr System

NASA Astrophysics Data System (ADS)

Bendjeghaba, Omar

2014-01-01

This paper presents a tuning approach based on Continuous firefly algorithm (CFA) to obtain the proportional-integral- derivative (PID) controller parameters in Automatic Voltage Regulator system (AVR). In the tuning processes the CFA is iterated to reach the optimal or the near optimal of PID controller parameters when the main goal is to improve the AVR step response characteristics. Conducted simulations show the effectiveness and the efficiency of the proposed approach. Furthermore the proposed approach can improve the dynamic of the AVR system. Compared with particle swarm optimization (PSO), the new CFA tuning method has better control system performance in terms of time domain specifications and set-point tracking.

What's New is What's Old: Use of Bode's Integral Theorem (circa 1945) to Provide Insight for 21st Century Spacecraft Attitude Control System Design Tuning

NASA Technical Reports Server (NTRS)

Ruth, Mike; Lebsock, Ken; Dennehy, Neil

2010-01-01

This paper revisits the Bode integral theorem, first described in 1945 for feedback amplifier design, in the context of modern satellite Attitude Control System (ACS) design tasks. Use of Bode's Integral clarifies in an elegant way the connection between open-loop stability margins and closed-loop bandwidth. More importantly it shows that there is a very strong tradeoff between disturbance rejection below the satellite controller design bandwidth, and disturbance amplification in the 'penalty region' just above the design bandwidth. This information has been successfully used to re-tune the control designs for several NASA science-mission satellites. The Appendix of this paper contains a complete summary of the relevant integral conservation theorems for stable, unstable, and non-minimum- phase plants.

Object-Oriented MDAO Tool with Aeroservoelastic Model Tuning Capability

NASA Technical Reports Server (NTRS)

Pak, Chan-gi; Li, Wesley; Lung, Shun-fat

2008-01-01

An object-oriented multi-disciplinary analysis and optimization (MDAO) tool has been developed at the NASA Dryden Flight Research Center to automate the design and analysis process and leverage existing commercial as well as in-house codes to enable true multidisciplinary optimization in the preliminary design stage of subsonic, transonic, supersonic and hypersonic aircraft. Once the structural analysis discipline is finalized and integrated completely into the MDAO process, other disciplines such as aerodynamics and flight controls will be integrated as well. Simple and efficient model tuning capabilities based on optimization problem are successfully integrated with the MDAO tool. More synchronized all phases of experimental testing (ground and flight), analytical model updating, high-fidelity simulations for model validation, and integrated design may result in reduction of uncertainties in the aeroservoelastic model and increase the flight safety.

Fine-tuning key parameters of an integrated reactor system for the simultaneous removal of COD, sulfate and ammonium and elemental sulfur reclamation.

PubMed

Yuan, Ye; Chen, Chuan; Liang, Bin; Huang, Cong; Zhao, Youkang; Xu, Xijun; Tan, Wenbo; Zhou, Xu; Gao, Shuang; Sun, Dezhi; Lee, Duujong; Zhou, Jizhong; Wang, Aijie

2014-03-30

In this paper, we proposed an integrated reactor system for simultaneous removal of COD, sulfate and ammonium (integrated C-S-N removal system) and investigated the key parameters of the system for a high level of elemental sulfur (S(0)) production. The system consisted of 4 main units: sulfate reduction and organic carbon removal (SR-CR), autotrophic and heterotrophic denitrifying sulfide removal (A&H-DSR), sulfur reclamation (SR), and aerated filter for aerobic nitrification (AN). In the system, the effects of key operational parameters on production of elemental sulfur were investigated, including hydraulic retention time (HRT) of each unit, sulfide/nitrate (S(2-)-S/NO3(-)-N) ratios, reflux ratios between the A&H-DSR and AN units, and loading rates of chemical oxygen demand (COD), sulfate and ammonium. Physico-chemical characteristics of biosulfur were studied for acquiring efficient S(0) recovery. The experiments successfully explored the optimum parameters for each unit and demonstrated 98% COD, 98% sulfate and 78% nitrogen removal efficiency. The optimum HRTs for SR-CR, A&H-DSR and AN were 12h, 3h and 3h, respectively. The reflux ratio of 3 could provide adequate S(2-)-S/NO3(-)-N ratio (approximately 1:1) to the A&H-DSR unit for obtaining maximum sulfur production. In this system, the maximum production of S(0) reached 90%, but only 60% S(0) was reclaimed from effluent. The S(0) that adhered to the outer layer of granules was deposited in the bottom of the A&H-DSR unit. Finally, the microbial community structure of the corresponding unit at different operational stage were analyzed by 16S rRNA gene based high throughput Illumina MiSeq sequencing and the potential function of dominant species were discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

Localized electrical fine tuning of passive microwave and radio frequency devices

DOEpatents

Findikoglu, Alp T.

2001-04-10

A method and apparatus for the localized electrical fine tuning of passive multiple element microwave or RF devices in which a nonlinear dielectric material is deposited onto predetermined areas of a substrate containing the device. An appropriate electrically conductive material is deposited over predetermined areas of the nonlinear dielectric and the signal line of the device for providing electrical contact with the nonlinear dielectric. Individual, adjustable bias voltages are applied to the electrically conductive material allowing localized electrical fine tuning of the devices. The method of the present invention can be applied to manufactured devices, or can be incorporated into the design of the devices so that it is applied at the time the devices are manufactured. The invention can be configured to provide localized fine tuning for devices including but not limited to coplanar waveguides, slotline devices, stripline devices, and microstrip devices.

Monolithic single mode interband cascade lasers with wide wavelength tunability

NASA Astrophysics Data System (ADS)

von Edlinger, M.; Weih, R.; Scheuermann, J.; Nähle, L.; Fischer, M.; Koeth, J.; Kamp, M.; Höfling, S.

2016-11-01

Monolithic two-section interband cascade lasers offering a wide wavelength tunability in the wavelength range around 3.7 μm are presented. Stable single mode emission in several wavelength channels was realized using the concept of binary superimposed gratings and two-segment Vernier-tuning. The wavelength selective elements in the two segments were based on specially designed lateral metal grating structures defined by electron beam lithography. A dual-step dry etch process provided electrical separation between the segments. Individual current control of the segments allowed wavelength channel selection as well as continuous wavelength tuning within channels. A discontinuous tuning range extending over 158 nm in up to six discrete wavelength channels was achieved. Mode hop free wavelength tuning up to 14 nm was observed within one channel. The devices can be operated in continuous wave mode up to 30 °C with the output powers of 3.5 mW around room temperature.

Earthquake Damping Device for Steel Frame

NASA Astrophysics Data System (ADS)

Zamri Ramli, Mohd; Delfy, Dezoura; Adnan, Azlan; Torman, Zaida

2018-04-01

Structures such as buildings, bridges and towers are prone to collapse when natural phenomena like earthquake occurred. Therefore, many design codes are reviewed and new technologies are introduced to resist earthquake energy especially on building to avoid collapse. The tuned mass damper is one of the earthquake reduction products introduced on structures to minimise the earthquake effect. This study aims to analyse the effectiveness of tuned mass damper by experimental works and finite element modelling. The comparisons are made between these two models under harmonic excitation. Based on the result, it is proven that installing tuned mass damper will reduce the dynamic response of the frame but only in several input frequencies. At the highest input frequency applied, the tuned mass damper failed to reduce the responses. In conclusion, in order to use a proper design of damper, detailed analysis must be carried out to have sufficient design based on the location of the structures with specific ground accelerations.

Electronic frequency tuning of the acousto-optic mode-locking device of a laser

NASA Astrophysics Data System (ADS)

Magdich, L. N.; Balakshy, V. I.; Mantsevich, S. N.

2017-11-01

The effect of the electronic tuning of the acoustic resonances in an acousto-optic mode-locking device of a laser is investigated theoretically and experimentally. The problem of the excitation of a Fabry-Perot acoustic resonator by a plate-like piezoelectric transducer (PET) is solved in the approximation of plane acoustic waves taking into consideration the actual parameters of an RF generator and the elements for matching the PET to the generator. Resonances are tuned by changing the matching inductance that was connected in parallel to the transducer of the acousto-optic cell. The cell used in the experiment was manufactured from fused silica and included a lithium niobate PET. Changes in the matching inductance in the range of 0.025 to 0.2 μH provided the acoustic-resonance frequency tuning by 0.19 MHz, which exceeds the acoustic- resonance half-width.

Online automatic tuning and control for fed-batch cultivation

PubMed Central

van Straten, Gerrit; van der Pol, Leo A.; van Boxtel, Anton J. B.

2007-01-01

Performance of controllers applied in biotechnological production is often below expectation. Online automatic tuning has the capability to improve control performance by adjusting control parameters. This work presents automatic tuning approaches for model reference specific growth rate control during fed-batch cultivation. The approaches are direct methods that use the error between observed specific growth rate and its set point; systematic perturbations of the cultivation are not necessary. Two automatic tuning methods proved to be efficient, in which the adaptation rate is based on a combination of the error, squared error and integral error. These methods are relatively simple and robust against disturbances, parameter uncertainties, and initialization errors. Application of the specific growth rate controller yields a stable system. The controller and automatic tuning methods are qualified by simulations and laboratory experiments with Bordetella pertussis. PMID:18157554

Spectrophone stabilized laser with line center offset frequency control

NASA Technical Reports Server (NTRS)

Kavaya, M. J.; Menzies, R. T. (Inventor)

1984-01-01

Continuous offset tuning of a frequency stabilized CW gas laser is achieved by using a spectrophone filled with the same gas as the laser for sensing a dither modulation, detecting a first or second derivative of the spectrophone output with a lock-in amplifier, the detected output of which is integrated, and applying the integrator output as a correction signal through a circuit which adds to the dither signal from an oscillator a dc offset that is adjusted with a potentiometer to a frequency offset from the absorption line center of the gas, but within the spectral linewidth of the gas. Tuning about that offset frequency is achieved by adding a dc value to the detected output of the dither modulation before integration using a potentiometer.

Simplified filtered Smith predictor for MIMO processes with multiple time delays.

PubMed

Santos, Tito L M; Torrico, Bismark C; Normey-Rico, Julio E

2016-11-01

This paper proposes a simplified tuning strategy for the multivariable filtered Smith predictor. It is shown that offset-free control can be achieved with step references and disturbances regardless of the poles of the primary controller, i.e., integral action is not explicitly required. This strategy reduces the number of design parameters and simplifies tuning procedure because the implicit integrative poles are not considered for design purposes. The simplified approach can be used to design continuous-time or discrete-time controllers. Three case studies are used to illustrate the advantages of the proposed strategy if compared with the standard approach, which is based on the explicit integrative action. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Tuning rules for robust FOPID controllers based on multi-objective optimization with FOPDT models.

PubMed

Sánchez, Helem Sabina; Padula, Fabrizio; Visioli, Antonio; Vilanova, Ramon

2017-01-01

In this paper a set of optimally balanced tuning rules for fractional-order proportional-integral-derivative controllers is proposed. The control problem of minimizing at once the integrated absolute error for both the set-point and the load disturbance responses is addressed. The control problem is stated as a multi-objective optimization problem where a first-order-plus-dead-time process model subject to a robustness, maximum sensitivity based, constraint has been considered. A set of Pareto optimal solutions is obtained for different normalized dead times and then the optimal balance between the competing objectives is obtained by choosing the Nash solution among the Pareto-optimal ones. A curve fitting procedure has then been applied in order to generate suitable tuning rules. Several simulation results show the effectiveness of the proposed approach. Copyright © 2016. Published by Elsevier Ltd.

Design of Octupole Channel for Integrable Optics Test Accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antipov, Sergey; Carlson, Kermit; Castellotti, Riccardo

We present the design of octupole channel for Integrable Optics Test Accelerator (IOTA). IOTA is a test accelerator at Fermilab, aimed to conduct research towards high-intensity machines. One of the goals of the project is to demonstrate high nonlinear betatron tune shifts while retaining large dynamic aperture in a realistic accelerator design. At the first stage the tune shift will be attained with a special channel of octupoles, which creates a variable octupole potential over a 1.8 m length. The channel consists of 18 identical air-cooled octupole magnets. The magnets feature a simple low-cost design, while meeting the requirements onmore » maximum gradient - up to 1.4 kG/cm³, and field quality - strength of harmonics below 1%. Numerical simulations show that the channel is capable of producing a nonlinear tune shift of 0.08 without restriction of dynamic aperture of the ring.« less

Infrared transparent graphene heater for silicon photonic integrated circuits.

PubMed

Schall, Daniel; Mohsin, Muhammad; Sagade, Abhay A; Otto, Martin; Chmielak, Bartos; Suckow, Stephan; Giesecke, Anna Lena; Neumaier, Daniel; Kurz, Heinrich

2016-04-18

Thermo-optical tuning of the refractive index is one of the pivotal operations performed in integrated silicon photonic circuits for thermal stabilization, compensation of fabrication tolerances, and implementation of photonic operations. Currently, heaters based on metal wires provide the temperature control in the silicon waveguide. The strong interaction of metal and light, however, necessitates a certain gap between the heater and the photonic structure to avoid significant transmission loss. Here we present a graphene heater that overcomes this constraint and enables an energy efficient tuning of the refractive index. We achieve a tuning power as low as 22 mW per free spectral range and fast response time of 3 µs, outperforming metal based waveguide heaters. Simulations support the experimental results and suggest that for graphene heaters the spacing to the silicon can be further reduced yielding the best possible energy efficiency and operation speed.

Integrated programmable photonic filter on the silicon-on-insulator platform.

PubMed

Liao, Shasha; Ding, Yunhong; Peucheret, Christophe; Yang, Ting; Dong, Jianji; Zhang, Xinliang

2014-12-29

We propose and demonstrate a silicon-on-insulator (SOI) on-chip programmable filter based on a four-tap finite impulse response structure. The photonic filter is programmable thanks to amplitude and phase modulation of each tap controlled by thermal heaters. We further demonstrate the tunability of the filter central wavelength, bandwidth and variable passband shape. The tuning range of the central wavelength is at least 42% of the free spectral range. The bandwidth tuning range is at least half of the free spectral range. Our scheme has distinct advantages of compactness, capability for integrating with electronics.

Bianisotropic metamaterial

DOEpatents

El-Kady, Ihab F.; Reinke, Charles M.

2017-07-18

The topology of the elements of a metamaterial can be engineered from its desired electromagnetic constitutive tensor using an inverse group theory method. Therefore, given a desired electromagnetic response and a generic metamaterial elemental design, group theory is applied to predict the various ways that the element can be arranged in three dimensions to produce the desired functionality. An optimizer can then be applied to an electromagnetic modeling tool to fine tune the values of the electromagnetic properties of the resulting metamaterial topology.

Functional conjugated pyridines via main-group element tuning.

PubMed

Stolar, Monika; Baumgartner, Thomas

2018-03-29

Pyridine-based materials have seen widespread attention for the development of n-type organic materials. In recent years, the incorporation of main-group elements has also explored significant advantages for the development and tunability of organic conjugated materials. The unique chemical and electronic structure of main-group elements has led to several enhancements in conventional organic materials. This Feature article highlights recent main-group based pyridine materials by discussing property enhancements and application in organic electronics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A.; Kotel'nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009

Using the space-resolved Brillouin light scattering spectroscopy we study the transformation of dynamic magnetization patterns in a bilayer multiferroic structure. We show that in the comparison with a single yttrium iron garnet (YIG) film magnetization distribution is transformed in the bilayer structure due to the coupling of waves propagating both in an YIG film (magnetic layer) and in a barium strontium titanate slab (ferroelectric layer). We present a simple electrodynamic model using the numerical finite element method to show the transformation of eigenmode spectrum of confined multiferroic. In particular, we demonstrate that the control over the dynamic magnetization and themore » transformation of spatial profiles of transverse modes in magnetic film of the bilayer structure can be performed by the tuning of the wavevectors of transverse modes. The studied confined multiferroic stripe can be utilized for fabrication of integrated dual tunable functional devices for magnonic applications.« less

A Low-noise Micromachined Millimeter-Wave Heterodyne Mixer using Nb Superconducting Tunnel Junctions

NASA Technical Reports Server (NTRS)

DeLange, Gert; Jacobson, Brian R.; Hu, Qing

1996-01-01

A heterodyne mixer with a micromachined horn antenna and a superconductor-insulator-superconductor (SIS) tunnel junction as mixing element is tested in the W-band (75-115 GHz) frequency range. Micromachined integrated horn antennas consist of a dipole antenna suspended on a thin Si3N4 dielectric membrane inside a pyramidal cavity etched in silicon. The mixer performance is optimized by using a backing plane behind the dipole antenna to tune out the capacitance of the tunnel junction. The lowest receiver noise temperature of 30 +/- 3 K (without any correction) is measured at 106 GHz with a 3-dB bandwidth of 8 GHz. This sensitivity is comparable to the state-of-the-art waveguide and quasi-optical SIS receivers, showing the potential use of micromachined horn antennas in imaging arrays.

Changes in the free-energy landscape of p38α MAP kinase through its canonical activation and binding events as studied by enhanced molecular dynamics simulations.

PubMed

Kuzmanic, Antonija; Sutto, Ludovico; Saladino, Giorgio; Nebreda, Angel R; Gervasio, Francesco L; Orozco, Modesto

2017-04-26

p38α is a Ser/Thr protein kinase involved in a variety of cellular processes and pathological conditions, which makes it a promising pharmacological target. Although the activity of the enzyme is highly regulated, its molecular mechanism of activation remains largely unexplained, even after decades of research. By using state-of-the-art molecular dynamics simulations, we decipher the key elements of the complex molecular mechanism refined by evolution to allow for a fine tuning of p38α kinase activity. Our study describes for the first time the molecular effects of different regulators of the enzymatic activity, and provides an integrative picture of the activation mechanism that explains the seemingly contradictory X-ray and NMR data.

Electro-optically tunable microwave source based on composite-cavity microchip laser.

PubMed

Qiao, Yunfei; Zheng, Shilie; Chi, Hao; Jin, Xiaofeng; Zhang, Xianmin

2012-12-17

A compact and electric tuning microwave source based on a diode-pumped composite Nd:YAG-LiNbO(3) cavity microchip laser is demonstrated. The electro-optical element introduces an electric tuning intra-cavity birefringence which causes a tunable frequency difference between two spilt orthogonal polarization states of a longitude mode. Thus a continuously tunable microwave signal with frequency up to 14.12 GHz can be easily generated by beating the two polarization modes on a high speed photodetector.

An infinitely-stiff elastic system via a tuned negative-stiffness component stabilized by rotation-produced gyroscopic forces

NASA Astrophysics Data System (ADS)

Kochmann, D. M.; Drugan, W. J.

2016-06-01

An elastic system containing a negative-stiffness element tuned to produce positive-infinite system stiffness, although statically unstable as is any such elastic system if unconstrained, is proved to be stabilized by rotation-produced gyroscopic forces at sufficiently high rotation rates. This is accomplished in possibly the simplest model of a composite structure (or solid) containing a negative-stiffness component that exhibits all these features, facilitating a conceptually and mathematically transparent, completely closed-form analysis.

Magneto-elastic Tuning of Ferroelectricity Within a Magnetoelectric Nanowire

DTIC Science & Technology

2011-01-01

collection of information if it does not display a currently valid OMB control number . 1. REPORT DATE OCT 2011 2. REPORT TYPE 3. DATES COVERED 00-00-2011...to 00-00-2011 4. TITLE AND SUBTITLE Magneto-elastic tuning of ferroelectricity within a magnetoelectric nanowire 5a. CONTRACT NUMBER 5b. GRANT... NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND

Laser-diode pumped dysprosium-doped lead thiogallate laser output wavelength temporal evolution and tuning possibilities at 4.3-4.7 um

NASA Astrophysics Data System (ADS)

Jelínková, Helena; Doroshenko, Maxim E.; Šulc, Jan; Němec, Michal; Jelínek, Michal; Osiko, Vjatcheslav V.; Badikov, Valerii V.; Badikov, Dmitri V.

2016-03-01

On the basis of our previous Dy3+:PbGa2S4 laser study, laser output wavelength temporal evolution as well as tuning possibilities in the range 4.3-4.7 μm were investigated. Active crystal was pumped by a fiber-coupled Brightlase Ultra- 50 diode laser (1.7 μm, max. power 7.5 W). Laser resonator was formed by flat dichroic pumping mirror (T = 70%@1.7 μm, R~100% @ 3.5 - 5 μm) and a concave (r = 200 mm) output coupler with R~99% @ 3.5 - 5 μm. The laser output wavelength dependence on the pump pulse duration and its evolution during the pulse was investigated first without any spectrally-selective element in the cavity. At pump pulse duration of 1 ms, generation just near Dy3+ fluorescence maximum of 4.35 μm has been observed. Prolongation of the pulse up to 5 ms led to similar lasing at 4.35 μm in the first millisecond, followed by simultaneous generation at 4.35 and 4.38 μm in the next millisecond, and further lasing at 4.6 μm till the end of the pump pulse. Increase of pump pulse duration up to 10 ms led to similar oscillation pulse development followed by generation at 4.6 μm only. Furthermore, output wavelength tuning using MgF2 birefringent filter as a cavity spectral selective element was investigated under 10 ms pumping. Almost continuous tuning without any significant dip has been observed within spectral range from 4.3 up to 4.7 μm. Due to practically closed cavity mean output power in the maximum of tuning curve was in the order of 400 μW.

A dynamic and ultrafast group delay tuning mechanism in two microcavities side-coupled with a waveguide system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Boyun; Wang, Tao, E-mail: wangtao@hust.edu.cn; Tang, Jian

2014-10-07

We theoretically propose a dynamic and ultrafast group delay tuning mechanism in two microcavities side-coupled to a waveguide system through external optical pump beams. The optical Kerr effect modulation method is applied to improve tuning rate with response time of subpicoseconds or even femtoseconds. The group delay of an all-optical analog to electromagnetically induced transparency effect can be controlled by tuning either the frequency of photonic crystal microcavities or the propagation phase of line waveguide. Group delay is controlled between 5.88 and 70.98 ps by dynamically tuning resonant frequencies of the microcavities. Alternatively, the group delay is controlled between 1.86more » and 12.08 ps by dynamically tuning the propagation phase of line waveguide. All observed schemes are analyzed rigorously through finite-difference time-domain simulations and coupled-mode formalism. Results show a new direction toward microstructure integration optical pulse trapping and all-optical dynamical storage of light devices in optical communication and quantum information processing.« less

Tuning the Curie temperature of L1{sub 0} ordered FePt thin films through site-specific substitution of Rh

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Dongbin, E-mail: dongbin.xu@seagate.com; Department of Materials Science and Engineering, National University of Singapore, Singapore 117576; Sun, Cheng-Jun, E-mail: cjsun@aps.anl.gov, E-mail: msecgm@nus.edu.sg

2014-10-14

In structurally ordered magnetic thin films, the Curie temperature (T{sub C}) of ferromagnetic films depends on the exchange integral of the short range ordered neighboring atoms. The exchange integral may be adjusted by controlling the elemental substitutional concentration at the lattice site of interest. We show how to control the T{sub C} in high anisotropy L1{sub 0} Fe{sub 50}Pt{sub 50} magnetic thin films by substituting Rh into the Pt site. Rh substitution in L1{sub 0} FePt modified the local atomic environment and the corresponding electronic properties, while retaining the ordered L1{sub 0} phase. The analysis of extended x-ray Absorption Finemore » Structure spectra shows that Rh uniformly substitutes for Pt in L1{sub 0} FePt. A model of antiferromagnetic defects caused by controlled Rh substitution of the Pt site, reducing the T{sub C,} is proposed to interpret this phenomenon and its validity is further examined by ab initio density functional calculations.« less

Updating the Finite Element Model of the Aerostructures Test Wing Using Ground Vibration Test Data

NASA Technical Reports Server (NTRS)

Lung, Shun-Fat; Pak, Chan-Gi

2009-01-01

Improved and/or accelerated decision making is a crucial step during flutter certification processes. Unfortunately, most finite element structural dynamics models have uncertainties associated with model validity. Tuning the finite element model using measured data to minimize the model uncertainties is a challenging task in the area of structural dynamics. The model tuning process requires not only satisfactory correlations between analytical and experimental results, but also the retention of the mass and stiffness properties of the structures. Minimizing the difference between analytical and experimental results is a type of optimization problem. By utilizing the multidisciplinary design, analysis, and optimization (MDAO) tool in order to optimize the objective function and constraints; the mass properties, the natural frequencies, and the mode shapes can be matched to the target data to retain the mass matrix orthogonality. This approach has been applied to minimize the model uncertainties for the structural dynamics model of the aerostructures test wing (ATW), which was designed and tested at the National Aeronautics and Space Administration Dryden Flight Research Center (Edwards, California). This study has shown that natural frequencies and corresponding mode shapes from the updated finite element model have excellent agreement with corresponding measured data.

Updating the Finite Element Model of the Aerostructures Test Wing using Ground Vibration Test Data

NASA Technical Reports Server (NTRS)

Lung, Shun-fat; Pak, Chan-gi

2009-01-01

Improved and/or accelerated decision making is a crucial step during flutter certification processes. Unfortunately, most finite element structural dynamics models have uncertainties associated with model validity. Tuning the finite element model using measured data to minimize the model uncertainties is a challenging task in the area of structural dynamics. The model tuning process requires not only satisfactory correlations between analytical and experimental results, but also the retention of the mass and stiffness properties of the structures. Minimizing the difference between analytical and experimental results is a type of optimization problem. By utilizing the multidisciplinary design, analysis, and optimization (MDAO) tool in order to optimize the objective function and constraints; the mass properties, the natural frequencies, and the mode shapes can be matched to the target data to retain the mass matrix orthogonality. This approach has been applied to minimize the model uncertainties for the structural dynamics model of the Aerostructures Test Wing (ATW), which was designed and tested at the National Aeronautics and Space Administration (NASA) Dryden Flight Research Center (DFRC) (Edwards, California). This study has shown that natural frequencies and corresponding mode shapes from the updated finite element model have excellent agreement with corresponding measured data.

Broadband tunable integrated CMOS pulser with 80-ps minimum pulse width for gain-switched semiconductor lasers.

PubMed

Chen, Shaoqiang; Diao, Shengxi; Li, Pengtao; Nakamura, Takahiro; Yoshita, Masahiro; Weng, Guoen; Hu, Xiaobo; Shi, Yanling; Liu, Yiqing; Akiyama, Hidefumi

2017-07-31

High power pulsed lasers with tunable pulse widths are highly favored in many applications. When combined with power amplification, gain-switched semiconductor lasers driven by broadband tunable electric pulsers can meet such requirements. For this reason, we designed and produced a low-cost integrated CMOS pulse generator with a minimum pulse width of 80 ps and a wide tuning range of up to 270 ns using a 40-nm microelectronic process technique. We used this pulser to drive a 1.3-µm semiconductor laser diode directly, and thereafter investigated the gain-switching properties of the laser system. The optical pulses consist of a spike followed by a steady state region. Tuning the width of the electrical pulse down to approximately 1.5 ns produces optical pulses consisting only of the spike, which has a minimum pulse-width of 100 ps. Moreover, the duration of the steady state can be tuned continuously by tuning the electrical pulse width, with a peak power of approximately 5 mW. The output voltage of the electric pulser has a tuning range of 0.8-1.5 V that can be used to directly drive semiconductor laser diodes with wavelengths in the near-infrared spectrum, which are suitable for power amplification with rare-earth doped fiber amplifiers.

Programmed optoelectronic time-pulse coded relational processor as base element for sorting neural networks

NASA Astrophysics Data System (ADS)

Krasilenko, Vladimir G.; Bardachenko, Vitaliy F.; Nikolsky, Alexander I.; Lazarev, Alexander A.

2007-04-01

In the paper we show that the biologically motivated conception of the use of time-pulse encoding gives the row of advantages (single methodological basis, universality, simplicity of tuning, training and programming et al) at creation and designing of sensor systems with parallel input-output and processing, 2D-structures of hybrid and neuro-fuzzy neurocomputers of next generations. We show principles of construction of programmable relational optoelectronic time-pulse coded processors, continuous logic, order logic and temporal waves processes, that lie in basis of the creation. We consider structure that executes extraction of analog signal of the set grade (order), sorting of analog and time-pulse coded variables. We offer optoelectronic realization of such base relational elements of order logic, which consists of time-pulse coded phototransformers (pulse-width and pulse-phase modulators) with direct and complementary outputs, sorting network on logical elements and programmable commutations blocks. We make estimations of basic technical parameters of such base devices and processors on their basis by simulation and experimental research: power of optical input signals - 0.200-20 μW, processing time - microseconds, supply voltage - 1.5-10 V, consumption power - hundreds of microwatts per element, extended functional possibilities, training possibilities. We discuss some aspects of possible rules and principles of training and programmable tuning on the required function, relational operation and realization of hardware blocks for modifications of such processors. We show as on the basis of such quasiuniversal hardware simple block and flexible programmable tuning it is possible to create sorting machines, neural networks and hybrid data-processing systems with the untraditional numerical systems and pictures operands.

Neural Representation of a Target Auditory Memory in a Cortico-Basal Ganglia Pathway

PubMed Central

Bottjer, Sarah W.

2013-01-01

Vocal learning in songbirds, like speech acquisition in humans, entails a period of sensorimotor integration during which vocalizations are evaluated via auditory feedback and progressively refined to achieve an imitation of memorized vocal sounds. This process requires the brain to compare feedback of current vocal behavior to a memory of target vocal sounds. We report the discovery of two distinct populations of neurons in a cortico-basal ganglia circuit of juvenile songbirds (zebra finches, Taeniopygia guttata) during vocal learning: (1) one in which neurons are selectively tuned to memorized sounds and (2) another in which neurons are selectively tuned to self-produced vocalizations. These results suggest that neurons tuned to learned vocal sounds encode a memory of those target sounds, whereas neurons tuned to self-produced vocalizations encode a representation of current vocal sounds. The presence of neurons tuned to memorized sounds is limited to early stages of sensorimotor integration: after learning, the incidence of neurons encoding memorized vocal sounds was greatly diminished. In contrast to this circuit, neurons known to drive vocal behavior through a parallel cortico-basal ganglia pathway show little selective tuning until late in learning. One interpretation of these data is that representations of current and target vocal sounds in the shell circuit are used to compare ongoing patterns of vocal feedback to memorized sounds, whereas the parallel core circuit has a motor-related role in learning. Such a functional subdivision is similar to mammalian cortico-basal ganglia pathways in which associative-limbic circuits mediate goal-directed responses, whereas sensorimotor circuits support motor aspects of learning. PMID:24005299

Quaternion error-based optimal control applied to pinpoint landing

NASA Astrophysics Data System (ADS)

Ghiglino, Pablo

Accurate control techniques for pinpoint planetary landing - i.e., the goal of achieving landing errors in the order of 100m for unmanned missions - is a complex problem that have been tackled in different ways in the available literature. Among other challenges, this kind of control is also affected by the well known trade-off in UAV control that for complex underlying models the control is sub-optimal, while optimal control is applied to simplifed models. The goal of this research has been the development new control algorithms that would be able to tackle these challenges and the result are two novel optimal control algorithms namely: OQTAL and HEX2OQTAL. These controllers share three key properties that are thoroughly proven and shown in this thesis; stability, accuracy and adaptability. Stability is rigorously demonstrated for both controllers. Accuracy is shown in results of comparing these novel controllers with other industry standard algorithms in several different scenarios: there is a gain in accuracy of at least 15% for each controller, and in many cases much more than that. A new tuning algorithm based on swarm heuristics optimisation was developed as well as part of this research in order to tune in an online manner the standard Proportional-Integral-Derivative (PID) controllers used for benchmarking. Finally, adaptability of these controllers can be seen as a combination of four elements: mathematical model extensibility, cost matrices tuning, reduced computation time required and finally no prior knowledge of the navigation or guidance strategies needed. Further simulations in real planetary landing trajectories has shown that these controllers have the capacity of achieving landing errors in the order of pinpoint landing requirements, making them not only very precise UAV controllers, but also potential candidates for pinpoint landing unmanned missions.

Acoustics of Korean percussion instruments: Pyeongyeong and pyeonjong

NASA Astrophysics Data System (ADS)

Yoo, Junehee

2005-11-01

The pyeongyeong and the pyeonjong have long been cherished as standard instruments in Korean court music. Pyeongyeong is a set of sixteen L-shaped chime stones and pyeonjong is a set of sixteen oval chime bells. To figure out the acoustical properties of the pyeongyeong and the pyeonjong, the vibrational modes are obtained by using FFT analyzers, accelerometer scanning, TV holography, and impact hammer testing. Especially to test the geometry effects on the tuning, the finite element method is introduced. The pyeongyeong covers one and one third octave from 528.6 Hz to 1262.8 Hz. The nominal frequency of the first stone, whangjong, is 528.6 Hz which is 17.6 cents higher than 523.25 Hz, the frequency of the C5 note in the A440 tempered scale. The second mode is tuned to about 1.5 times the nominal frequency, which means the second partial is tuned to be a perfect fifth above the nominal. The third mode is tuned to about 2.3 times the nominal frequency. Mode shapes of a gyeong from three different methods agree with each other. In most cases, the modes seem to be combinations of bending and torsional motion. The calculated results by using the finite element method show that the ratio frequencies of higher modes rise as the vertex angle of a gyeong changes from 90 degrees to 180 degrees. The curvatures of the baseline affect the tuning of the stone, but the effects are smaller than those of the vertex angle. The geometry of the gyeong affects the tuning of the stone. The pyeonjong covers one and one third octave from 267.95 Hz to 634.74 Hz. The nominal frequency of the first bell, whangiong , is 267.95 Hz. The second mode (i.e. (2,0)b) is tuned to about 1.09 times the nominal frequency (i.e. (2,0)a) mode. The third mode (i.e. (3,0)b) is tuned to about 2.62 times the nominal frequency. The fourth mode (3,0), is tuned 2.72 times the nominal frequency, a perfect fourth plus 39 cents above the octave. Mode shapes of the bells, determined by electronic TV holography, are described by m, the number of nodal meridians and n, the number of nodal circles. Like Chinese two-tone bells, the bells in pyeonjong have "a" and "b" modes with the same (m, n) designation. The mode shapes agree very well with the results from former studies.

PID controller tuning using metaheuristic optimization algorithms for benchmark problems

NASA Astrophysics Data System (ADS)

Gholap, Vishal; Naik Dessai, Chaitali; Bagyaveereswaran, V.

2017-11-01

This paper contributes to find the optimal PID controller parameters using particle swarm optimization (PSO), Genetic Algorithm (GA) and Simulated Annealing (SA) algorithm. The algorithms were developed through simulation of chemical process and electrical system and the PID controller is tuned. Here, two different fitness functions such as Integral Time Absolute Error and Time domain Specifications were chosen and applied on PSO, GA and SA while tuning the controller. The proposed Algorithms are implemented on two benchmark problems of coupled tank system and DC motor. Finally, comparative study has been done with different algorithms based on best cost, number of iterations and different objective functions. The closed loop process response for each set of tuned parameters is plotted for each system with each fitness function.

Nonlinear dynamics of a pulse-coupled neural oscillator model of orientation tuning in the visual cortex

NASA Astrophysics Data System (ADS)

Bressloff, P. C.; Bressloff, N. W.

2000-02-01

Orientation tuning in a ring of pulse-coupled integrate-and-fire (IF) neurons is analyzed in terms of spontaneous pattern formation. It is shown how the ring bifurcates from a synchronous state to a non-phase-locked state whose spike trains are characterized by quasiperiodic variations of the inter-spike intervals (ISIs) on closed invariant circles. The separation of these invariant circles in phase space results in a localized peak of activity as measured by the time-averaged firing rate of the neurons. This generates a sharp orientation tuning curve that can lock to a slowly rotating, weakly tuned external stimulus. For fast synapses, breakup of the quasiperiodic orbits occurs leading to high spike time variability suggestive of chaos.

Parameters-tuning of PID controller for automatic voltage regulators using the African buffalo optimization.

PubMed

Odili, Julius Beneoluchi; Mohmad Kahar, Mohd Nizam; Noraziah, A

2017-01-01

In this paper, an attempt is made to apply the African Buffalo Optimization (ABO) to tune the parameters of a PID controller for an effective Automatic Voltage Regulator (AVR). Existing metaheuristic tuning methods have been proven to be quite successful but there were observable areas that need improvements especially in terms of the system's gain overshoot and steady steady state errors. Using the ABO algorithm where each buffalo location in the herd is a candidate solution to the Proportional-Integral-Derivative parameters was very helpful in addressing these two areas of concern. The encouraging results obtained from the simulation of the PID Controller parameters-tuning using the ABO when compared with the performance of Genetic Algorithm PID (GA-PID), Particle-Swarm Optimization PID (PSO-PID), Ant Colony Optimization PID (ACO-PID), PID, Bacteria-Foraging Optimization PID (BFO-PID) etc makes ABO-PID a good addition to solving PID Controller tuning problems using metaheuristics.

Fine-Tuning Medium-of-Instruction Policy in Hong Kong: Acquisition of Language and Content-Based Subject Knowledge

ERIC Educational Resources Information Center

Poon, Anita Y. K.; Lau, Connie M. Y.

2016-01-01

Facing a dramatic decline in English standards over the past decade, the Hong Kong Government introduced the "Fine-tuning Medium of Instruction (MOI) policy" in 2010 to address the grievances arising from different sectors in the community. Integrating content and language has become popular in second/foreign language teaching in recent…

A Recurrent Network Model of Somatosensory Parametric Working Memory in the Prefrontal Cortex

PubMed Central

Miller, Paul; Brody, Carlos D; Romo, Ranulfo; Wang, Xiao-Jing

2015-01-01

A parametric working memory network stores the information of an analog stimulus in the form of persistent neural activity that is monotonically tuned to the stimulus. The family of persistent firing patterns with a continuous range of firing rates must all be realizable under exactly the same external conditions (during the delay when the transient stimulus is withdrawn). How this can be accomplished by neural mechanisms remains an unresolved question. Here we present a recurrent cortical network model of irregularly spiking neurons that was designed to simulate a somatosensory working memory experiment with behaving monkeys. Our model reproduces the observed positively and negatively monotonic persistent activity, and heterogeneous tuning curves of memory activity. We show that fine-tuning mathematically corresponds to a precise alignment of cusps in the bifurcation diagram of the network. Moreover, we show that the fine-tuned network can integrate stimulus inputs over several seconds. Assuming that such time integration occurs in neural populations downstream from a tonically persistent neural population, our model is able to account for the slow ramping-up and ramping-down behaviors of neurons observed in prefrontal cortex. PMID:14576212

Tunable, Electrically Small, Inductively Coupled Antenna for Transportable Ionospheric Heating

NASA Astrophysics Data System (ADS)

Esser, Benedikt; Mauch, Daniel; Dickens, James; Mankowski, John; Neuber, Andreas

2018-04-01

An electrically small antenna is evaluated for use as the principle radiating element in a mobile ionospheric heating array. Consisting of a small loop antenna inductively coupled to a capacitively loaded loop, the electrically small antenna provides high efficiency with the capability of being tuned within the range of ionospheric heating. At a factor 60 smaller in area than a High-Frequency Active Auroral Research Program element, this antenna provides a compact, efficient radiating element for mobile ionospheric heating. A prototype antenna at 10 MHz was built to study large-scale feasibility and possible use with photoconductive semiconductor switch-based drivers. Based on the experimental study, the design has been extrapolated to a small 6 × 4 array of antennas. At a total power input of 16.1 MW this array is predicted to provide 3.6-GW effective radiated power typically required for ionospheric heating. Array cross talk is addressed, including effects upon individual antenna port parameters. Tuning within the range of ionospheric heating, 3-10 MHz, is made possible without the use of lossy dielectrics through a large capacitive area suited to tune the antenna. Considerations for high power operation across the band are provided including a method of driving the antenna with a simple switcher requiring no radio frequency cabling. Source matching may be improved via adjustment of the coupling between small loop antenna and capacitively loaded loop improving |S11| from -1 to -21 dB at 3 MHz.

Commissioning and first tests of the MAGIC telescope

NASA Astrophysics Data System (ADS)

Baixeras, C.; Bastieri, D.; Bigongiari, C.; Blanch, O.; Blanchot, G.; Bock, R.; Bretz, T.; Chilingarian, A.; Coarasa, J. A.; Colombo, E.; Contreras, J. C.; Corti, D.; Cortina, J.; Domingo, C.; Domingo, E.; Ferenc, D.; Fernández, E.; Flix, J.; Fonseca, V.; Font, L.; Galante, N.; Gaug, M.; Garczarczyk, M.; Gebauer, J.; Giller, M.; Goebel, F.; Hengstebeck, T.; Jacone, P.; de Jager, O. C.; Kalekin, O.; Kestel, M.; Kneiske, T.; Laille, A.; López, M.; López, J.; Lorenz, E.; Mannheim, K.; Mariotti, M.; Martínez, M.; Mase, K.; Merck, M.; Meucci, M.; Miralles, L.; Mirzoyan, R.; Moralejo, A.; Wilhelmi, E. Oña; Orduña, R.; Paneque, D.; Paoletti, R.; Pascoli, D.; Pavel, N.; Pegna, R.; Peruzzo, L.; Piccioli, A.; Roberts, A.; Reyes, R.; Saggion, A.; Sánchez, A.; Sartori, P.; Scalzotto, V.; Schweizer, T.; Sillanpaa, A.; Sobczynska, D.; Stamerra, A.; Stepanian, A.; Stiehler, R.; Takalo, L.; Teshima, M.; Tonello, N.; Torres, A.; Turini, N.; Vitale, V.; Volkov, S.; Wagner, R. M.; Wibig, T.; Wittek, W.

2004-02-01

Major Atmospheric Gamma Imaging Cherenkov telescope is starting its operations with a set of engineering runs to tune the telescope subsystem elements to be ready for the first physics campaign. Many technical improvements have been developed and implemented in several elements of the telescope to reach the lowest energy threshold ever obtained by an Imaging Atmospheric Cherenkov Telescope. A general description of the telescope is presented. The commissioning of the telescope's elements is described and the expected performances are reviewed with the final detector set-up.

Study of the fractional order proportional integral controller for the permanent magnet synchronous motor based on the differential evolution algorithm.

PubMed

Zheng, Weijia; Pi, Youguo

2016-07-01

A tuning method of the fractional order proportional integral speed controller for a permanent magnet synchronous motor is proposed in this paper. Taking the combination of the integral of time and absolute error and the phase margin as the optimization index, the robustness specification as the constraint condition, the differential evolution algorithm is applied to search the optimal controller parameters. The dynamic response performance and robustness of the obtained optimal controller are verified by motor speed-tracking experiments on the motor speed control platform. Experimental results show that the proposed tuning method can enable the obtained control system to achieve both the optimal dynamic response performance and the robustness to gain variations. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Tilt-tuned etalon locking for tunable laser stabilization.

PubMed

Gibson, Bradley M; McCall, Benjamin J

2015-06-15

Locking to a fringe of a tilt-tuned etalon provides a simple, inexpensive method for stabilizing tunable lasers. Here, we describe the use of such a system to stabilize an external-cavity quantum cascade laser; the locked laser has an Allan deviation of approximately 1 MHz over a one-second integration period, and has a single-scan tuning range of approximately 0.4  cm(-1). The system is robust, with minimal alignment requirements and automated lock acquisition, and can be easily adapted to different wavelength regions or more stringent stability requirements with minor alterations.

A Self-Tuning Kalman Filter for Autonomous Navigation Using the Global Positioning System (GPS)

NASA Technical Reports Server (NTRS)

Truong, Son H.

1999-01-01

Most navigation systems currently operated by NASA are ground-based, and require extensive support to produce accurate results. Recently developed systems that use Kalman filter and GPS (Global Positioning Systems) data for orbit determination greatly reduce dependency on ground support, and have potential to provide significant economies for NASA spacecraft navigation. These systems, however, still rely on manual tuning from analysts. A sophisticated neuro-fuzzy component fully integrated with the flight navigation system can perform the self-tuning capability for the Kalman filter and help the navigation system recover from estimation errors in real time.

A Self-Tuning Kalman Filter for Autonomous Navigation using the Global Positioning System (GPS)

NASA Technical Reports Server (NTRS)

Truong, S. H.

1999-01-01

Most navigation systems currently operated by NASA are ground-based, and require extensive support to produce accurate results. Recently developed systems that use Kalman filter and GPS data for orbit determination greatly reduce dependency on ground support, and have potential to provide significant economies for NASA spacecraft navigation. These systems, however, still rely on manual tuning from analysts. A sophisticated neuro-fuzzy component fully integrated with the flight navigation system can perform the self-tuning capability for the Kalman filter and help the navigation system recover from estimation errors in real time.

A Hardware Platform for Tuning of MEMS Devices Using Closed-Loop Frequency Response

NASA Technical Reports Server (NTRS)

Ferguson, Michael I.; MacDonald, Eric; Foor, David

2005-01-01

We report on the development of a hardware platform for integrated tuning and closed-loop operation of MEMS gyroscopes. The platform was developed and tested for the second generation JPL/Boeing Post-Resonator MEMS gyroscope. The control of this device is implemented through a digital design on a Field Programmable Gate Array (FPGA). A software interface allows the user to configure, calibrate, and tune the bias voltages on the micro-gyro. The interface easily transitions to an embedded solution that allows for the miniaturization of the system to a single chip.

Micromagnetic simulation of static magnetic properties and tuning of anisotropy strength in two dimensional square antidot elements

NASA Astrophysics Data System (ADS)

Dash, S.; Satish, S.; Parida, B.; Satapathy, S.; Ipsita, N. S.; Joshi, R. S.

2018-04-01

We demonstrate the tailoring of anisotropy in magnetic nano-wire element using finite element method based micromagnetic simulation. We calculate the magentostatic properties for the structure by simulating hysteresis for these nano wire elements. The angular variation of remanence for the structures of different dimensions is used as the depiction to establish fourfold magnetic anisotropy. The change of anisotropy strength, which is the ratio of squareness of hysteresis loop in hard axis to easy axis, is demonstrated in this study which is one of the most important parameters to utilize these nanowire elements in multi state magnetic memory application.

Model-based analysis of pattern motion processing in mouse primary visual cortex

PubMed Central

Muir, Dylan R.; Roth, Morgane M.; Helmchen, Fritjof; Kampa, Björn M.

2015-01-01

Neurons in sensory areas of neocortex exhibit responses tuned to specific features of the environment. In visual cortex, information about features such as edges or textures with particular orientations must be integrated to recognize a visual scene or object. Connectivity studies in rodent cortex have revealed that neurons make specific connections within sub-networks sharing common input tuning. In principle, this sub-network architecture enables local cortical circuits to integrate sensory information. However, whether feature integration indeed occurs locally in rodent primary sensory areas has not been examined directly. We studied local integration of sensory features in primary visual cortex (V1) of the mouse by presenting drifting grating and plaid stimuli, while recording the activity of neuronal populations with two-photon calcium imaging. Using a Bayesian model-based analysis framework, we classified single-cell responses as being selective for either individual grating components or for moving plaid patterns. Rather than relying on trial-averaged responses, our model-based framework takes into account single-trial responses and can easily be extended to consider any number of arbitrary predictive models. Our analysis method was able to successfully classify significantly more responses than traditional partial correlation (PC) analysis, and provides a rigorous statistical framework to rank any number of models and reject poorly performing models. We also found a large proportion of cells that respond strongly to only one stimulus class. In addition, a quarter of selectively responding neurons had more complex responses that could not be explained by any simple integration model. Our results show that a broad range of pattern integration processes already take place at the level of V1. This diversity of integration is consistent with processing of visual inputs by local sub-networks within V1 that are tuned to combinations of sensory features. PMID:26300738

Mixing in microfluidic devices and enhancement methods

PubMed Central

Ward, Kevin; Fan, Z Hugh

2015-01-01

Mixing in microfluidic devices presents a challenge due to laminar flows in microchannels, which result from low Reynolds numbers determined by the channel’s hydraulic diameter, flow velocity, and solution’s kinetic viscosity. To address this challenge, novel methods of mixing enhancement within microfluidic devices have been explored for a variety of applications. Passive mixing methods have been created, including those using ridges or slanted wells within the microchannels, as well as their variations with improved performance by varying geometry and patterns, by changing the properties of channel surfaces, and by optimization via simulations. In addition, active mixing methods including microstirrers, acoustic mixers, and flow pulsation have been investigated and integrated into microfluidic devices to enhance mixing in a more controllable manner. In general, passive mixers are easy to integrate, but difficult to control externally by users after fabrication. Active mixers usually take efforts to integrate within a device and they require external components (e.g. power sources) to operate. However, they can be controlled by users to a certain degree for tuned mixing. In this article, we provide a general overview of a number of passive and active mixers, discuss their advantages and disadvantages, and make suggestions on choosing a mixing method for a specific need as well as advocate possible integration of key elements of passive and active mixers to harness the advantages of both types. PMID:26549938

Mixing in microfluidic devices and enhancement methods.

PubMed

Ward, Kevin; Fan, Z Hugh

2015-09-01

Mixing in microfluidic devices presents a challenge due to laminar flows in microchannels, which result from low Reynolds numbers determined by the channel's hydraulic diameter, flow velocity, and solution's kinetic viscosity. To address this challenge, novel methods of mixing enhancement within microfluidic devices have been explored for a variety of applications. Passive mixing methods have been created, including those using ridges or slanted wells within the microchannels, as well as their variations with improved performance by varying geometry and patterns, by changing the properties of channel surfaces, and by optimization via simulations. In addition, active mixing methods including microstirrers, acoustic mixers, and flow pulsation have been investigated and integrated into microfluidic devices to enhance mixing in a more controllable manner. In general, passive mixers are easy to integrate, but difficult to control externally by users after fabrication. Active mixers usually take efforts to integrate within a device and they require external components (e.g. power sources) to operate. However, they can be controlled by users to a certain degree for tuned mixing. In this article, we provide a general overview of a number of passive and active mixers, discuss their advantages and disadvantages, and make suggestions on choosing a mixing method for a specific need as well as advocate possible integration of key elements of passive and active mixers to harness the advantages of both types.

Polythiophene-fullerene based photodetectors: tuning of spectral response and application in photoluminescence based (bio)chemical sensors.

PubMed

Nalwa, Kanwar S; Cai, Yuankun; Thoeming, Aaron L; Shinar, Joseph; Shinar, Ruth; Chaudhary, Sumit

2010-10-01

A photoluminescence (PL)-based oxygen and glucose sensor utilizing inorganic or organic light emitting diode as the light source, and polythiophene: fullerene type bulk-heterojunction devices as photodetectors, for both intensity and decay-time based monitoring of the sensing element's PL. The sensing element is based on the oxygen-sensitive dye Pt-octaethylporphyrin embedded in a polystyrene matrix.

Experimental realization of an on-chip all-optical analogue to electromagnetically induced transparency.

PubMed

Xu, Qianfan; Sandhu, Sunil; Povinelli, Michelle L; Shakya, Jagat; Fan, Shanhui; Lipson, Michal

2006-03-31

We provide the first experimental observation of structure tuning of the electromagnetically induced transparency-like spectrum in integrated on-chip optical resonator systems. The system consists of coupled silicon ring resonators with 10 microm diameter on silicon, where the coherent interference between the two coupled resonators is tuned. We measured a transparency-resonance mode with a quality factor of 11,800.

Follow on Research for Multi-Utility Technology Test Bed Aircraft at NASA Dryden Flight Research Center (FY13 Progress Report)

NASA Technical Reports Server (NTRS)

Pak, Chan-Gi

2013-01-01

Modern aircraft employ a significant fraction of their weight in composite materials to reduce weight and improve performance. Aircraft aeroservoelastic models are typically characterized by significant levels of model parameter uncertainty due to the composite manufacturing process. Small modeling errors in the finite element model will eventually induce errors in the structural flexibility and mass, thus propagating into unpredictable errors in the unsteady aerodynamics and the control law design. One of the primary objectives of Multi Utility Technology Test-bed (MUTT) aircraft is the flight demonstration of active flutter suppression, and therefore in this study, the identification of the primary and secondary modes for the structural model tuning based on the flutter analysis of MUTT aircraft. The ground vibration test-validated structural dynamic finite element model of the MUTT aircraft is created in this study. The structural dynamic finite element model of MUTT aircraft is improved using the in-house Multi-disciplinary Design, Analysis, and Optimization tool. In this study, two different weight configurations of MUTT aircraft have been improved simultaneously in a single model tuning procedure.

Tuning and performance evaluation of PID controller for superheater steam temperature control of 200 MW boiler using gain phase assignment algorithm

NASA Astrophysics Data System (ADS)

Begum, A. Yasmine; Gireesh, N.

2018-04-01

In superheater, steam temperature is controlled in a cascade control loop. The cascade control loop consists of PI and PID controllers. To improve the superheater steam temperature control the controller's gains in a cascade control loop has to be tuned efficiently. The mathematical model of the superheater is derived by sets of nonlinear partial differential equations. The tuning methods taken for study here are designed for delay plus first order transfer function model. Hence from the dynamical model of the superheater, a FOPTD model is derived using frequency response method. Then by using Chien-Hrones-Reswick Tuning Algorithm and Gain-Phase Assignment Algorithm optimum controller gains has been found out based on the least value of integral time weighted absolute error.

A 5GHz Band Low Noise and Wide Tuning Range Si-CMOS VCO with a Novel Varactors Pair Circuit

NASA Astrophysics Data System (ADS)

Ta, Tuan Thanh; Kameda, Suguru; Takagi, Tadashi; Tsubouchi, Kazuo

In this paper, a fully integrated 5GHz voltage controlled oscillator (VCO) is presented. The VCO is designed with 0.18µm silicon complementary metal oxide semiconductor (Si-CMOS) process. To achieve low phase noise, a novel varactors pair circuit is proposed to cancel effects of capacitance fluctuation that makes harmonic currents which increase phase noise of VCO. The VCO with the proposed varactor circuit has tuning range from 5.1GHz to 6.1GHz (relative value of 17.9%) and phase noise of lower than -110.8dBc/Hz at 1MHz offset over the full tuning range. Figure-of-merit-with-tuning-range (FOMT) of the proposed VCO is -182dBc/Hz.

Airborne 2-Micron Double-Pulsed Integrated Path Differential Absorption Lidar for Column CO2 Measurement

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer F.; Remus, Ruben G.; Fay, James J.; Reithmaier, Karl

2014-01-01

Double-pulse 2-micron lasers have been demonstrated with energy as high as 600 millijouls and up to 10 Hz repetition rate. The two laser pulses are separated by 200 microseconds and can be tuned and locked separately. Applying double-pulse laser in DIAL system enhances the CO2 measurement capability by increasing the overlap of the sampled volume between the on-line and off-line. To avoid detection complicity, integrated path differential absorption (IPDA) lidar provides higher signal-to-noise ratio measurement compared to conventional range-resolved DIAL. Rather than weak atmospheric scattering returns, IPDA rely on the much stronger hard target returns that is best suited for airborne platforms. In addition, the IPDA technique measures the total integrated column content from the instrument to the hard target but with weighting that can be tuned by the transmitter. Therefore, the transmitter could be tuned to weight the column measurement to the surface for optimum CO2 interaction studies or up to the free troposphere for optimum transport studies. Currently, NASA LaRC is developing and integrating a double-Pulsed 2-micron direct detection IPDA lidar for CO2 column measurement from an airborne platform. The presentation will describe the development of the 2-micron IPDA lidar system and present the airborne measurement of column CO2 and will compare to in-situ measurement for various ground target of different reflectivity.

An automatically tuning intrusion detection system.

PubMed

Yu, Zhenwei; Tsai, Jeffrey J P; Weigert, Thomas

2007-04-01

An intrusion detection system (IDS) is a security layer used to detect ongoing intrusive activities in information systems. Traditionally, intrusion detection relies on extensive knowledge of security experts, in particular, on their familiarity with the computer system to be protected. To reduce this dependence, various data-mining and machine learning techniques have been deployed for intrusion detection. An IDS is usually working in a dynamically changing environment, which forces continuous tuning of the intrusion detection model, in order to maintain sufficient performance. The manual tuning process required by current systems depends on the system operators in working out the tuning solution and in integrating it into the detection model. In this paper, an automatically tuning IDS (ATIDS) is presented. The proposed system will automatically tune the detection model on-the-fly according to the feedback provided by the system operator when false predictions are encountered. The system is evaluated using the KDDCup'99 intrusion detection dataset. Experimental results show that the system achieves up to 35% improvement in terms of misclassification cost when compared with a system lacking the tuning feature. If only 10% false predictions are used to tune the model, the system still achieves about 30% improvement. Moreover, when tuning is not delayed too long, the system can achieve about 20% improvement, with only 1.3% of the false predictions used to tune the model. The results of the experiments show that a practical system can be built based on ATIDS: system operators can focus on verification of predictions with low confidence, as only those predictions determined to be false will be used to tune the detection model.

A lithium niobate electro-optic tunable Bragg filter fabricated by electron beam lithography

NASA Astrophysics Data System (ADS)

Pierno, L.; Dispenza, M.; Secchi, A.; Fiorello, A.; Foglietti, V.

2008-06-01

We have designed and fabricated a lithium niobate tunable Bragg filter patterned by electron beam lithography and etched by reactive ion etching. Devices with 1 mm, 2 mm and 4 mm length and 360 and 1080 nm Bragg period, with 5 pm V-1 tuning efficiency, have been characterized. Some applications were identified. Optical simulation based on finite element model (FEM) software showing the optical filtering curve and the coupling factor dependence on the manufacturing parameter is reported. The tuning of the filter window position is electro-optically controlled.

Dancing to a Different Tune: Adaptive Evolution Fine-Tunes Protein Dynamics

DTIC Science & Technology

2015-09-01

homotropic regulator of E. coli PK1. The kcat of the PEP titrations are similar both with (266 ± 3 s-1) and without (243 ± 4 s-1) FBP in solution...affinity; 3 ) P70Q, P70T and A301S (five populations), which have similar PEP affinity to the wild-type, but now have PEP cooperativity in the presence...PROGRAM ELEMENT NUMBER 5b. GRANT NUMBER 5a. CONTRACT NUMBER Form Approved OMB NO. 0704-0188 3 . DATES COVERED (From - To) - UU UU UU UU 19-12-2015

Creating a Test Validated Structural Dynamic Finite Element Model of the X-56A Aircraft

NASA Technical Reports Server (NTRS)

Pak, Chan-Gi; Truong, Samson

2014-01-01

Small modeling errors in the finite element model will eventually induce errors in the structural flexibility and mass, thus propagating into unpredictable errors in the unsteady aerodynamics and the control law design. One of the primary objectives of the Multi Utility Technology Test-bed, X-56A aircraft, is the flight demonstration of active flutter suppression, and therefore in this study, the identification of the primary and secondary modes for the structural model tuning based on the flutter analysis of the X-56A aircraft. The ground vibration test-validated structural dynamic finite element model of the X-56A aircraft is created in this study. The structural dynamic finite element model of the X-56A aircraft is improved using a model tuning tool. In this study, two different weight configurations of the X-56A aircraft have been improved in a single optimization run. Frequency and the cross-orthogonality (mode shape) matrix were the primary focus for improvement, while other properties such as center of gravity location, total weight, and offdiagonal terms of the mass orthogonality matrix were used as constraints. The end result was a more improved and desirable structural dynamic finite element model configuration for the X-56A aircraft. Improved frequencies and mode shapes in this study increased average flutter speeds of the X-56A aircraft by 7.6% compared to the baseline model.

Creating a Test-Validated Finite-Element Model of the X-56A Aircraft Structure

NASA Technical Reports Server (NTRS)

Pak, Chan-Gi; Truong, Samson

2014-01-01

Small modeling errors in a finite-element model will eventually induce errors in the structural flexibility and mass, thus propagating into unpredictable errors in the unsteady aerodynamics and the control law design. One of the primary objectives of the X-56A Multi-Utility Technology Testbed aircraft is the flight demonstration of active flutter suppression and, therefore, in this study, the identification of the primary and secondary modes for the structural model tuning based on the flutter analysis of the X-56A aircraft. The ground-vibration test-validated structural dynamic finite-element model of the X-56A aircraft is created in this study. The structural dynamic finite-element model of the X-56A aircraft is improved using a model-tuning tool. In this study, two different weight configurations of the X-56A aircraft have been improved in a single optimization run. Frequency and the cross-orthogonality (mode shape) matrix were the primary focus for improvement, whereas other properties such as c.g. location, total weight, and off-diagonal terms of the mass orthogonality matrix were used as constraints. The end result was an improved structural dynamic finite-element model configuration for the X-56A aircraft. Improved frequencies and mode shapes in this study increased average flutter speeds of the X-56A aircraft by 7.6% compared to the baseline model.

Single-particle dynamics in a nonlinear accelerator lattice: attaining a large tune spread with octupoles in IOTA

NASA Astrophysics Data System (ADS)

Antipov, S. A.; Nagaitsev, S.; Valishev, A.

2017-04-01

Fermilab is constructing the Integrable Optics Test Accelerator (IOTA) as the centerpiece of the Accelerator R&D Program towards high-intensity circular machines. One of the factors limiting the beam intensity in present circular accelerators is collective instabilities, which can be suppressed by a spread of betatron frequencies (tunes) through the Landau damping mechanism or by an external damper, if the instability is slow enough. The spread is usually created by octupole magnets, which introduce the tune dependence on the amplitude and, in some cases, by a chromatic spread (tune dependence on particle's momentum). The introduction of octupoles usually has both beneficial (improved Landau damping) and harmful properties, such as a resonant behavior and a reduction of the dynamic aperture. One of the research goals at the IOTA ring is to achieve a large betatron tune spread, while retaining a large dynamic aperture, using conventional octupole magnets in a special but realistic accelerator configuration. The configuration, although not integrable by design, approximates an autonomous 2D Hamiltonian system. In this paper, we present results of computer simulations of an electron beam in the IOTA by particle tracking and the Frequency Map Analysis. The results show that the ring's octupole magnets can be configured to provide a betatron tune shift of 0.08 (for particles at large amplitudes) with the dynamical aperture of over 20 beam sigma for a 150-MeV electron beam. The influence of the synchrotron motion, lattice errors, and magnet imperfections is insignificant for the parameters and levels of tolerances set by the design of the ring. The described octupole insert could be beneficial for enhancing Landau damping in high intensity machines.

A reconfigurable liquid metal antenna driven by electrochemically controlled capillarity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, M.; Adams, J. J., E-mail: jjadams2@ncsu.edu; Trlica, C.

2015-05-21

We describe a new electrochemical method for reversible, pump-free control of liquid eutectic gallium and indium (EGaIn) in a capillary. Electrochemical deposition (or removal) of a surface oxide on the EGaIn significantly lowers (or increases) its interfacial tension as a means to induce the liquid metal in (or out) of the capillary. A fabricated prototype demonstrates this method in a reconfigurable antenna application in which EGaIn forms the radiating element. By inducing a change in the physical length of the EGaIn, the operating frequency of the antenna tunes over a large bandwidth. This purely electrochemical mechanism uses low, DC voltagesmore » to tune the antenna continuously and reversibly between 0.66 GHz and 3.4 GHz resulting in a 5:1 tuning range. Gain and radiation pattern measurements agree with electromagnetic simulations of the device, and its measured radiation efficiency varies from 41% to 70% over its tuning range.« less

The dynamics and tuning of orchestral crotales

NASA Astrophysics Data System (ADS)

Deutsch, Bradley M.; Ramirez, Cherie L.; Moore, Thomas R.

2004-10-01

An experimental and theoretical investigation of the acoustic and vibrational properties of orchestral crotales within the range C6 to C8 is reported. Interferograms of the acoustically important modes of vibration are presented and the frequencies are reported. It is shown that the acoustic spectra of crotales are not predicted by assuming that they are either thin circular plates or annular plates clamped at the center, despite the physical resemblance to these objects. Results from finite element analysis are presented that demonstrate how changing the size of the central mass affects the tuning of the instruments, and it is concluded that crotales are not currently designed to ensure optimal tuning. The possibility of using annular plates as crotales is also investigated and the physical parameters for such a set of instruments are presented. .

SEMICONDUCTOR INTEGRATED CIRCUITS: An asymmetric MOSFET-C band-pass filter with on-chip charge pump auto-tuning

NASA Astrophysics Data System (ADS)

Fangxiong, Chen; Min, Lin; Heping, Ma; Hailong, Jia; Yin, Shi; Forster, Dai

2009-08-01

An asymmetric MOSFET-C band-pass filter (BPF) with on chip charge pump auto-tuning is presented. It is implemented in UMC (United Manufacturing Corporation) 0.18 μm CMOS process technology. The filter system with auto-tuning uses a master-slave technique for continuous tuning in which the charge pump outputs 2.663 V, much higher than the power supply voltage, to improve the linearity of the filter. The main filter with third order low-pass and second order high-pass properties is an asymmetric band-pass filter with bandwidth of 2.730-5.340 MHz. The in-band third order harmonic input intercept point (IIP3) is 16.621 dBm, with 50 Ω as the source impedance. The input referred noise is about 47.455 μVrms. The main filter dissipates 3.528 mW while the auto-tuning system dissipates 2.412 mW from a 1.8 V power supply. The filter with the auto-tuning system occupies 0.592 mm2 and it can be utilized in GPS (global positioning system) and Bluetooth systems.

DNA nanotechnology for nanophotonic applications.

PubMed

Samanta, Anirban; Banerjee, Saswata; Liu, Yan

2015-02-14

DNA nanotechnology has touched the epitome of miniaturization by integrating various nanometer size particles with nanometer precision. This enticing bottom-up approach has employed small DNA tiles, large multi-dimensional polymeric structures or more recently DNA origami to organize nanoparticles of different inorganic materials, small organic molecules or macro-biomolecules like proteins, and RNAs into fascinating patterns that are difficult to achieve by other conventional methods. Here, we are especially interested in the self-assembly of nanomaterials that are potentially attractive elements in the burgeoning field of nanophotonics. These materials include plasmonic nanoparticles, quantum dots, fluorescent organic dyes, etc. DNA based self-assembly allows excellent control over distance, orientation and stoichiometry of these nano-elements that helps to engineer intelligent systems that can potentially pave the path for future technology. Many outstanding structures have been fabricated that are capable of fine tuning optical properties, such as fluorescence intensity and lifetime modulation, enhancement of Raman scattering and emergence of circular dichroism responses. Within the limited scope of this review we have tried to give a glimpse of the development of this still nascent but highly promising field to its current status as well as the existing challenges before us.

THE ROLES OF METAL IONS IN REGULATION BY RIBOSWITCHES

PubMed Central

2012-01-01

Metal ions are required by all organisms in order to execute an array of essential molecular functions. They play a critical role in many catalytic mechanisms and structural properties. Proper homeostasis of ions is critical; levels that are aberrantly low or high are deleterious to cellular physiology. To maintain stable intracellular pools, metal ion-sensing regulatory (metalloregulatory) proteins couple metal ion concentration fluctuations with expression of genes encoding for cation transport or sequestration. However, these transcriptional-based regulatory strategies are not the only mechanisms by which organisms coordinate metal ions with gene expression. Intriguingly, a few classes of signal-responsive RNA elements have also been discovered to function as metalloregulatory agents. This suggests that RNA-based regulatory strategies can be precisely tuned to intracellular metal ion pools, functionally akin to metalloregulatory proteins. In addition to these metal-sensing regulatory RNAs, there is a yet broader role for metal ions in directly assisting the structural integrity of other signal-responsive regulatory RNA elements. In this chapter, we discuss how the intimate physicochemical relationship between metal ions and nucleic acids is important for the structure and function of metal ion- and metabolite-sensing regulatory RNAs. PMID:22010271

SEMICONDUCTOR INTEGRATED CIRCUITS 8.64-11.62 GHz CMOS VCO and divider in a zero-IF 802.11a/b/g WLAN and Bluetooth application

NASA Astrophysics Data System (ADS)

Yu, Sun; Niansong, Mei; Bo, Lu; Yumei, Huang; Zhiliang, Hong

2010-10-01

A fully integrated VCO and divider implemented in SMIC 0.13-μm RFCMOS 1P8M technology with a 1.2 V supply voltage is presented. The frequency of the VCO is tuning from 8.64 to 11.62 GHz while the quadrature LO signals for 802.11a WLAN in 5.8 GHz band or for 802.11b/g WLAN and Bluetooth in 2.4 GHz band can be obtained by a frequency division by 2 or 4, respectively. A 6 bit switched capacitor array is applied for precise tuning of all necessary frequency bands. The testing results show that the VCO has a phase noise of—113 dBc @ 1 MHz offset from the carrier of 5.5 GHz by dividing VCO output by two and the VCO core consumes 3.72 mW. The figure-of-merit for the tuning-range (FOMT) of the VCO is -192.6 dBc/Hz.

Neuronal integration in visual cortex elevates face category tuning to conscious face perception

PubMed Central

Fahrenfort, Johannes J.; Snijders, Tineke M.; Heinen, Klaartje; van Gaal, Simon; Scholte, H. Steven; Lamme, Victor A. F.

2012-01-01

The human brain has the extraordinary capability to transform cluttered sensory input into distinct object representations. For example, it is able to rapidly and seemingly without effort detect object categories in complex natural scenes. Surprisingly, category tuning is not sufficient to achieve conscious recognition of objects. What neural process beyond category extraction might elevate neural representations to the level where objects are consciously perceived? Here we show that visible and invisible faces produce similar category-selective responses in the ventral visual cortex. The pattern of neural activity evoked by visible faces could be used to decode the presence of invisible faces and vice versa. However, only visible faces caused extensive response enhancements and changes in neural oscillatory synchronization, as well as increased functional connectivity between higher and lower visual areas. We conclude that conscious face perception is more tightly linked to neural processes of sustained information integration and binding than to processes accommodating face category tuning. PMID:23236162

Small slot waveguide rings for on-chip quantum optical circuits.

PubMed

Rotenberg, Nir; Türschmann, Pierre; Haakh, Harald R; Martin-Cano, Diego; Götzinger, Stephan; Sandoghdar, Vahid

2017-03-06

Nanophotonic interfaces between single emitters and light promise to enable new quantum optical technologies. Here, we use a combination of finite element simulations and analytic quantum theory to investigate the interaction of various quantum emitters with slot-waveguide rings. We predict that for rings with radii as small as 1.44 μm, with a Q-factor of 27,900, near-unity emitter-waveguide coupling efficiencies and emission enhancements on the order of 1300 can be achieved. By tuning the ring geometry or introducing losses, we show that realistic emitter-ring systems can be made to be either weakly or strongly coupled, so that we can observe Rabi oscillations in the decay dynamics even for micron-sized rings. Moreover, we demonstrate that slot waveguide rings can be used to directionally couple emission, again with near-unity efficiency. Our results pave the way for integrated solid-state quantum circuits involving various emitters.

Recent advances in superconducting-mixer simulations

NASA Technical Reports Server (NTRS)

Withington, S.; Kennedy, P. R.

1992-01-01

Over the last few years, considerable progress have been made in the development of techniques for fabricating high-quality superconducting circuits, and this success, together with major advances in the theoretical understanding of quantum detection and mixing at millimeter and submillimeter wavelengths, has made the development of CAD techniques for superconducting nonlinear circuits an important new enterprise. For example, arrays of quasioptical mixers are now being manufactured, where the antennas, matching networks, filters and superconducting tunnel junctions are all fabricated by depositing niobium and a variety of oxides on a single quartz substrate. There are no adjustable tuning elements on these integrated circuits, and therefore, one must be able to predict their electrical behavior precisely. This requirement, together with a general interest in the generic behavior of devices such as direct detectors and harmonic mixers, has lead us to develop a range of CAD tools for simulating the large-signal, small-signal, and noise behavior of superconducting tunnel junction circuits.

Synchrotron X-ray micro-beam studies of ancient Egyptian make-up

NASA Astrophysics Data System (ADS)

Martinetto, P.; Anne, M.; Dooryhée, E.; Drakopoulos, M.; Dubus, M.; Salomon, J.; Simionovici, A.; Walter, Ph.

2001-07-01

Vases full of make-up are most often present in the burial furniture of Egyptian tombs dated from the pharaonic period. The powdered cosmetics made of isolated grains are analysed to identify their trace element signature. From this signature we identify the provenance of the mineral ingredients in the make-up and we observe different impurities in products, which have been demonstrated as synthetic substances by previous works. Focused X-ray micro-beam ( 2×5 μm2) is successively tuned at 11 keV, below the L III absorption edge of Pb, and 31.8 keV for global characterisation of the metal impurities. The fluorescence signal integrated over each single grain is detected against the X-ray micro-diffraction pattern collected in transmission with a bi-dimensional detector. Furthermore, for galena grains rich in Zn, the XANES signal at the K-absorption edge of Zn shows its immediate nearest-neighbour environment.

Wave bandgap formation and its evolution in two-dimensional phononic crystals composed of rubber matrix with periodic steel quarter-cylinders

NASA Astrophysics Data System (ADS)

Li, Peng; Wang, Guan; Luo, Dong; Cao, Xiaoshan

2018-02-01

The band structure of a two-dimensional phononic crystal, which is composed of four homogenous steel quarter-cylinders immersed in rubber matrix, is investigated and compared with the traditional steel/rubber crystal by the finite element method (FEM). It is revealed that the frequency can then be tuned by changing the distance between adjacent quarter-cylinders. When the distance is relatively small, the integrality of scatterers makes the inner region inside them almost motionless, so that they can be viewed as a whole at high-frequencies. In the case of relatively larger distance, the interaction between each quarter-cylinder and rubber will introduce some new bandgaps at relatively low-frequencies. Lastly, the point defect states induced by the four quarter-cylinders are revealed. These results will be helpful in fabricating devices, such as vibration insulators and acoustic/elastic filters, whose band frequencies can be manipulated artificially.

Changes in the free-energy landscape of p38α MAP kinase through its canonical activation and binding events as studied by enhanced molecular dynamics simulations

PubMed Central

Kuzmanic, Antonija; Sutto, Ludovico; Saladino, Giorgio; Nebreda, Angel R; Gervasio, Francesco L; Orozco, Modesto

2017-01-01

p38α is a Ser/Thr protein kinase involved in a variety of cellular processes and pathological conditions, which makes it a promising pharmacological target. Although the activity of the enzyme is highly regulated, its molecular mechanism of activation remains largely unexplained, even after decades of research. By using state-of-the-art molecular dynamics simulations, we decipher the key elements of the complex molecular mechanism refined by evolution to allow for a fine tuning of p38α kinase activity. Our study describes for the first time the molecular effects of different regulators of the enzymatic activity, and provides an integrative picture of the activation mechanism that explains the seemingly contradictory X-ray and NMR data. DOI: http://dx.doi.org/10.7554/eLife.22175.001 PMID:28445123

Double synchronized switch harvesting (DSSH): a new energy harvesting scheme for efficient energy extraction.

PubMed

Lallart, Mickaël; Garbuio, Lauric; Petit, Lionel; Richard, Claude; Guyomar, Daniel

2008-10-01

This paper presents a new technique for optimized energy harvesting using piezoelectric microgenerators called double synchronized switch harvesting (DSSH). This technique consists of a nonlinear treatment of the output voltage of the piezoelectric element. It also integrates an intermediate switching stage that ensures an optimal harvested power whatever the load connected to the microgenerator. Theoretical developments are presented considering either constant vibration magnitude, constant driving force, or independent extraction. Then experimental measurements are carried out to validate the theoretical predictions. This technique exhibits a constant output power for a wide range of load connected to the microgenerator. In addition, the extracted power obtained using such a technique allows a gain up to 500% in terms of maximal power output compared with the standard energy harvesting method. It is also shown that such a technique allows a fine-tuning of the trade-off between vibration damping and energy harvesting.

Recurrent connectivity can account for the dynamics of disparity processing in V1

PubMed Central

Samonds, Jason M.; Potetz, Brian R.; Tyler, Christopher W.; Lee, Tai Sing

2013-01-01

Disparity tuning measured in the primary visual cortex (V1) is described well by the disparity energy model, but not all aspects of disparity tuning are fully explained by the model. Such deviations from the disparity energy model provide us with insight into how network interactions may play a role in disparity processing and help to solve the stereo correspondence problem. Here, we propose a neuronal circuit model with recurrent connections that provides a simple account of the observed deviations. The model is based on recurrent connections inferred from neurophysiological observations on spike timing correlations, and is in good accord with existing data on disparity tuning dynamics. We further performed two additional experiments to test predictions of the model. First, we increased the size of stimuli to drive more neurons and provide a stronger recurrent input. Our model predicted sharper disparity tuning for larger stimuli. Second, we displayed anti-correlated stereograms, where dots of opposite luminance polarity are matched between the left- and right-eye images and result in inverted disparity tuning in the disparity energy model. In this case, our model predicted reduced sharpening and strength of inverted disparity tuning. For both experiments, the dynamics of disparity tuning observed from the neurophysiological recordings in macaque V1 matched model simulation predictions. Overall, the results of this study support the notion that, while the disparity energy model provides a primary account of disparity tuning in V1 neurons, neural disparity processing in V1 neurons is refined by recurrent interactions among elements in the neural circuit. PMID:23407952

Tiny radio is based on diamond effects

NASA Astrophysics Data System (ADS)

2017-02-01

You could soon be tuning into “Diamond FM”, thanks to a new radio receiver based on atomic-scale defects in diamond, unveiled by physicists at Harvard University in the US and Element Six in the UK.

Critical elements on fitting the Bayesian multivariate Poisson Lognormal model

NASA Astrophysics Data System (ADS)

Zamzuri, Zamira Hasanah binti

2015-10-01

Motivated by a problem on fitting multivariate models to traffic accident data, a detailed discussion of the Multivariate Poisson Lognormal (MPL) model is presented. This paper reveals three critical elements on fitting the MPL model: the setting of initial estimates, hyperparameters and tuning parameters. These issues have not been highlighted in the literature. Based on simulation studies conducted, we have shown that to use the Univariate Poisson Model (UPM) estimates as starting values, at least 20,000 iterations are needed to obtain reliable final estimates. We also illustrated the sensitivity of the specific hyperparameter, which if it is not given extra attention, may affect the final estimates. The last issue is regarding the tuning parameters where they depend on the acceptance rate. Finally, a heuristic algorithm to fit the MPL model is presented. This acts as a guide to ensure that the model works satisfactorily given any data set.

Stable and wavelength-tunable silicon-micro-ring-resonator based erbium-doped fiber laser.

PubMed

Yang, L G; Yeh, C H; Wong, C Y; Chow, C W; Tseng, F G; Tsang, H K

2013-02-11

In this work, we propose and demonstrate a stable and wavelength-tunable erbium-doped fiber (EDF) ring laser. Here, a silicon-on-insulator (SOI)-based silicon-micro-ring-resonator (SMRR) is used as the wavelength selective element inside the fiber ring cavity. A uniform period grating coupler (GC) is used to couple between the SMRR and single mode fiber (SMF) and serves also as a polarization dependent element in the cavity. The output lasing wavelength of the proposed fiber laser can be tuned at a tuning step of 2 nm (defined by the free spectral range (FSR) of the SMRR) in a bandwidth of 35.2 nm (1532.00 to 1567.20 nm), which is defined by the gain of the EDF. The optical-signal-to-noise-ratio (OSNR) of each lasing wavelength is larger than 42.0 dB. In addition, the output stabilities of power and wavelength are also discussed.

Optofluidic-Tunable Color Filters And Spectroscopy Based On Liquid-Crystal Microflows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuennet, J. G.; Vasdekis, Andreas E.; Psaltis, D.

The integration of color filters with microfluidics has attracted substantial attention in recent years, for on-chip absorption, fluorescence, or Raman analysis. We describe such tunable filters based on the micro-flow of liquid crystals. The filter operation is based on the wavelength dependent liquid crystal birefringence that can be tuned by modifying the flow velocity field in the microchannel. The latter is possible both temporally and spatially by varying the inlet pressure and the channel geometry respectively. We explored the use of these optofluidic filters for on-chip absorption spectroscopy; by integrating the distance dependent color filter with a dye-filled micro-channel, themore » absorption spectrum of a dye could be measured. Liquid crystal microflows simplify substantially the optofluidic integration, actuation and tuning of color filters for lab-on-a-chip spectroscopic applications.« less

New approach to radar rainfall measurement

NASA Technical Reports Server (NTRS)

Atlas, David; Rosenfeld, Daniel; Wolff, David B.

1991-01-01

This paper integrates individual studies of the Area-Time Integrals method and climatic tuning methods. The latter is extended to a new approach which generalizes the technique so that it is no longer restricted to power law relations between effective reflectivity and rain rate.

An Agile Beam Transmit Array Using Coupled Oscillator Phase Control

NASA Technical Reports Server (NTRS)

Pogorzelski, Ronald S.; Scaramastra, Rocco P.; Huang, John; Beckon, Robert J.; Petree, Steve M.; Chavez, Cosme

1993-01-01

A few years ago York and colleagues suggested that injection locking of voltage controlled oscillators could be used to implement beam steering in a phased array [I]. The scheme makes use of the fact that when an oscillator is injection locked to an external signal, the phase difference between the output of the oscillator and the injection signal is governed by the difference between the injection frequency and the free running frequency of the oscillator (the frequency to which the oscillator is tuned). Thus, if voltage controlled oscillators (VCOs) are used, this phase difference is controlled by an applied voltage. Now, if a set of such oscillators are coupled to nearest neighbors, they can be made to mutually injection lock and oscillate as an ensemble. If they are all tuned to the same frequency, they will all oscillate in phase. Thus, if the outputs are connected to radiating elements forming a linear array, the antenna will radiate normal to the line of elements. Scanning is accomplished by antisymmetrically detuning the end oscillators in the array by application of a pair of appropriate voltages to their tuning ports. This results in a linear phase progression across the array which is just the phasing required to scan the beam. The scan angle is determined by the degree of detuning. We have constructed a seven element one dimensional agile beam array at S-band based on the above principle. Although, a few such arrays have been built in the past, this array possesses two unique features. First, the VCO MMICs have buffer amplifiers which isolate the output from the tuning circuit, and second, the oscillators are weakly coupled to each other at their resonant circuits rather than their outputs. This results in a convenient isolation between the oscillator array design and the radiating aperture design. An important parameter in the design is the so called coupling phase which determines the phase shift of the signals passing from one oscillator to its neighbors. Using this array, we have been able to verify the theoretical predictions concerning the effect of this phase on both the locking range and ensemble frequency of the array. However, the scan range achieved fell somewhat short of the theoretical value because of the amplitude variation of the oscillator outputs with tuning.

Compact wideband filter element-based on complementary split-ring resonators

NASA Astrophysics Data System (ADS)

Horestani, Ali K.; Shaterian, Zahra; Withayachumnankul, Withawat; Fumeaux, Christophe; Al-Sarawi, Said; Abbott, Derek

2011-12-01

A double resonance defected ground structure is proposed as a filter element. The structure involves a transmission line loaded with complementary split ring resonators embedded in a dumbbell shape defected ground structure. By using a parametric study, it is demonstrated that the two resonance frequencies can be independently tuned. Therefore the structure can be used for different applications such as dual bandstop filters and wide bandstop filters.

Quadrature transmit coil for breast imaging at 7 tesla using forced current excitation for improved homogeneity.

PubMed

McDougall, Mary Preston; Cheshkov, Sergey; Rispoli, Joseph; Malloy, Craig; Dimitrov, Ivan; Wright, Steven M

2014-11-01

To demonstrate the use of forced current excitation (FCE) to create homogeneous excitation of the breast at 7 tesla, insensitive to the effects of asymmetries in the electrical environment. FCE was implemented on two breast coils: one for quadrature (1) H imaging and one for proton-decoupled (13) C spectroscopy. Both were a Helmholtz-saddle combination, with the saddle tuned to 298 MHz for imaging and 75 MHz for spectroscopy. Bench measurements were acquired to demonstrate the ability to force equal currents on elements in the presence of asymmetric loading to improve homogeneity. Modeling and temperature measurements were conducted per safety protocol. B1 mapping, imaging, and proton-decoupled (13) C spectroscopy were demonstrated in vivo. Using FCE to ensure balanced currents on elements enabled straightforward tuning and maintaining of isolation between quadrature elements of the coil. Modeling and bench measurements confirmed homogeneity of the field, which resulted in images with excellent fat suppression and in broadband proton-decoupled carbon-13 spectra. FCE is a straightforward approach to ensure equal currents on multiple coil elements and a homogeneous excitation field, insensitive to the effects of asymmetries in the electrical environment. This enabled effective breast imaging and proton-decoupled carbon-13 spectroscopy at 7T. © 2014 Wiley Periodicals, Inc.

M sub-shell X-ray fluorescence cross-section measurements for six elements in the range Z = 78-92 at tuned synchrotron photon energies 5, 7 and 9 keV.

NASA Astrophysics Data System (ADS)

Bansal, Himani; Tiwari, M. K.; Mittal, Raj

2018-01-01

M sub-shell X-ray fluorescence cross-sections of elements Pt, Au, Hg, Pb, Th and U have been measured with linearly polarized photon beams from Indus-II synchrotron source at Raja Ramanna Centre for Advanced Technology (RRCAT), India at tuned 5, 7 and 9 keV energies less than the L3 edge energy of elements. Measurements at present energies and elements are not available in literature. Therefore, measured cross-sections for Mξ, Mδ, Mα, Mβ, Mγ, Mm1 and Mm2 group of X-rays were compared with calculated theoretical values based upon Non Relativistic Hartree-Slater (NRHS) and relativistic Dirac-Fork (DF) and Dirac-Hartree-Slater (DHS) models. The measured cross-sections along with our earlier quoted measurements at 8 and 10 keV by Kaur et al. [Nucl. Instrum. Meth. B, 2014; 320: 37] are found in good agreement with DF and DHS values around 20% deviations and are highly deviated from NRHS values. Most of the spots of observed high deviations in measured and theoretical cross-sections are found to coincide with the presence of crisscrosses/sharp variations in contributing physical parameters photo-ionization cross-sections σMi's and Coster-Kronig yields fij's with Zs.

Numerical performance analysis of quartz tuning fork-based force sensors

NASA Astrophysics Data System (ADS)

Dagdeviren, Omur E.; Schwarz, Udo D.

2017-01-01

Quartz tuning fork-based force sensors where one prong is immobilized onto a holder while the other one is allowed to oscillate freely (‘qPlus’ configuration) are in widespread use for high-resolution scanning probe microscopy applications. Due to the small size of the tuning forks (≈3 mm) and the complexity of the sensor assemblies, the reliable and repeatable manufacturing of the sensors has been challenging. In this paper, we investigate the contribution of the amount and location of the epoxy glue used to attach the tuning fork to its holder on the sensor’s performance. Towards this end, we use finite element analysis to model the entire sensor assembly and to perform static and dynamic numerical simulations. Our analysis reveals that increasing the thickness of the epoxy layer between prong and holder results in a decrease of the sensor’s spring constant, eigenfrequency, and quality factor while showing an increasing deviation from oscillation in its primary modal shape. Adding epoxy at the sides of the tuning fork also leads to a degradation of the quality factor even though in this case, spring constant and eigenfrequency rise in tandem with a lessening of the deviation from its ideal modal shape.

Electrical birefringence tuning of VCSELs

NASA Astrophysics Data System (ADS)

Pusch, Tobias; Lindemann, Markus; Gerhardt, Nils C.; Hofmann, Martin R.; Michalzik, Rainer

2018-02-01

The birefringence splitting B, which is the frequency difference between the two fundamental linear polarization modes in vertical-cavity surface-emitting lasers (VCSELs), is the key parameter determining the polarization dynamics of spin-VCSELs that can be much faster than the intensity dynamics. For easy handling and control, electrical tuning of B is favored. This was realized in an integrated chip by thermally induced strain via asymmetric heating with a birefringence tuning range of 45 GHz. In this paper we present our work on VCSEL structures mounted on piezoelectric transducers for strain generation. Furthermore we show a combination of both techniques, namely VCSELs with piezo-thermal birefringence tunability.

Real-Time Ozone Detection Based on a Microfabricated Quartz Crystal Tuning Fork Sensor

PubMed Central

Wang, Rui; Tsow, Francis; Zhang, Xuezhi; Peng, Jhih-Hong; Forzani, Erica S.; Chen, Yongsheng; Crittenden, John C.; Destaillats, Hugo; Tao, Nongjian

2009-01-01

A chemical sensor for ozone based on an array of microfabricated tuning forks is described. The tuning forks are highly sensitive and stable, with low power consumption and cost. The selective detection is based on the specific reaction of the polymer with ozone. With a mass detection limit of ∼2 pg/mm2 and response time of 1 second, the sensor coated with a polymer sensing material can detect ppb-level ozone in air. The sensor is integrated into a miniaturized wearable device containing a detection circuit, filtration, battery and wireless communication chip, which is ideal for personal and microenvironmental chemical exposure monitoring. PMID:22346720

Si photonics technology for future optical interconnection

NASA Astrophysics Data System (ADS)

Zheng, Xuezhe; Krishnamoorthy, Ashok V.

2011-12-01

Scaling of computing systems require ultra-efficient interconnects with large bandwidth density. Silicon photonics offers a disruptive solution with advantages in reach, energy efficiency and bandwidth density. We review our progress in developing building blocks for ultra-efficient WDM silicon photonic links. Employing microsolder based hybrid integration with low parasitics and high density, we optimize photonic devices on SOI platforms and VLSI circuits on more advanced bulk CMOS technology nodes independently. Progressively, we successfully demonstrated single channel hybrid silicon photonic transceivers at 5 Gbps and 10 Gbps, and 80 Gbps arrayed WDM silicon photonic transceiver using reverse biased depletion ring modulators and Ge waveguide photo detectors. Record-high energy efficiency of less than 100fJ/bit and 385 fJ/bit were achieved for the hybrid integrated transmitter and receiver, respectively. Waveguide grating based optical proximity couplers were developed with low loss and large optical bandwidth to enable multi-layer intra/inter-chip optical interconnects. Thermal engineering of WDM devices by selective substrate removal, together with WDM link using synthetic wavelength comb, we significantly improved the device tuning efficiency and reduced the tuning range. Using these innovative techniques, two orders of magnitude tuning power reduction was achieved. And tuning cost of only a few 10s of fJ/bit is expected for high data rate WDM silicon photonic links.

An express method for optimally tuning an analog controller with respect to integral quality criteria

NASA Astrophysics Data System (ADS)

Golinko, I. M.; Kovrigo, Yu. M.; Kubrak, A. I.

2014-03-01

An express method for optimally tuning analog PI and PID controllers is considered. An integral quality criterion with minimizing the control output is proposed for optimizing control systems. The suggested criterion differs from existing ones in that the control output applied to the technological process is taken into account in a correct manner, due to which it becomes possible to maximally reduce the expenditure of material and/or energy resources in performing control of industrial equipment sets. With control organized in such manner, smaller wear and longer service life of control devices are achieved. A unimodal nature of the proposed criterion for optimally tuning a controller is numerically demonstrated using the methods of optimization theory. A functional interrelation between the optimal controller parameters and dynamic properties of a controlled plant is numerically determined for a single-loop control system. The results obtained from simulation of transients in a control system carried out using the proposed and existing functional dependences are compared with each other. The proposed calculation formulas differ from the existing ones by a simple structure and highly accurate search for the optimal controller tuning parameters. The obtained calculation formulas are recommended for being used by specialists in automation for design and optimization of control systems.

Tribotronic Tuning Diode for Active Analog Signal Modulation.

PubMed

Zhou, Tao; Yang, Zhi Wei; Pang, Yaokun; Xu, Liang; Zhang, Chi; Wang, Zhong Lin

2017-01-24

Realizing active interaction with external environment/stimuli is a great challenge for current electronics. In this paper, a tribotronic tuning diode (TTD) is proposed by coupling a variable capacitance diode and a triboelectric nanogenerator in free-standing sliding mode. When the friction layer is sliding on the device surface for electrification, a reverse bias voltage is created and applied to the diode for tuning the junction capacitance. When the sliding distance increases from 0 to 25 mm, the capacitance of the TTD decreases from about 39 to 8 pF. The proposed TTD has been integrated into analog circuits and exhibited excellent performances in frequency modulation, phase shift, and filtering by sliding a finger. This work has demonstrated tunable diode and active analog signal modulation by tribotronics, which has great potential to replace ordinary variable capacitance diodes in various practical applications such as signal processing, electronic tuning circuits, precise tuning circuits, active sensor networks, electronic communications, remote controls, flexible electronics, etc.

Simulation of process identification and controller tuning for flow control system

NASA Astrophysics Data System (ADS)

Chew, I. M.; Wong, F.; Bono, A.; Wong, K. I.

2017-06-01

PID controller is undeniably the most popular method used in controlling various industrial processes. The feature to tune the three elements in PID has allowed the controller to deal with specific needs of the industrial processes. This paper discusses the three elements of control actions and improving robustness of controllers through combination of these control actions in various forms. A plant model is simulated using the Process Control Simulator in order to evaluate the controller performance. At first, the open loop response of the plant is studied by applying a step input to the plant and collecting the output data from the plant. Then, FOPDT of physical model is formed by using both Matlab-Simulink and PRC method. Then, calculation of controller’s setting is performed to find the values of Kc and τi that will give satisfactory control in closed loop system. Then, the performance analysis of closed loop system is obtained by set point tracking analysis and disturbance rejection performance. To optimize the overall physical system performance, a refined tuning of PID or detuning is further conducted to ensure a consistent resultant output of closed loop system reaction to the set point changes and disturbances to the physical model. As a result, the PB = 100 (%) and τi = 2.0 (s) is preferably chosen for setpoint tracking while PB = 100 (%) and τi = 2.5 (s) is selected for rejecting the imposed disturbance to the model. In a nutshell, selecting correlation tuning values is likewise depended on the required control’s objective for the stability performance of overall physical model.

Experimental and analytical study on vibration control effects of eddy-current tuned mass dampers under seismic excitations

NASA Astrophysics Data System (ADS)

Lu, Zheng; Huang, Biao; Zhang, Qi; Lu, Xilin

2018-05-01

Eddy-current tuned mass dampers (EC-TMDs) are non-contacting passive control devices and are developed on the basis of conventional tuned mass dampers. They comprise a solid mass, a stiffness element, and a damping element, wherein the damping mechanism originates from eddy currents. By relative motion between a non-magnetic conductive metal and a permanent magnet in a dynamic system, a time-varying magnetic field is induced in the conductor, thereby generating eddy currents. The eddy currents induce a magnetic field with opposite polarity, causing repulsive forces, i.e., damping forces. This technology can overcome the drawbacks of conventional tuned mass dampers, such as limited service life, deterioration of mechanical properties, and undesired additional stiffness. The experimental and analytical study of this system installed on a multi-degree-of-freedom structure is presented in this paper. A series of shaking table tests were conducted on a five-story steel-frame model with/without an EC-TMD to evaluate the effectiveness and performance of the EC-TMD in suppressing the vibration of the model under seismic excitations. The experimental results show that the EC-TMD can effectively reduce the displacement response, acceleration response, interstory drift ratio, and maximum strain of the columns under different earthquake excitations. Moreover, an analytical method was proposed on the basis of electromagnetic and structural dynamic theories. A comparison between the test and simulation results shows that the simulation method can be used to estimate the response of structures with an EC-TMD under earthquake excitations with acceptable accuracy.

Ultra-wideband tunable resonator based on varactor-loaded complementary split-ring resonators on a substrate-integrated waveguide for microwave sensor applications.

PubMed

Sam, Somarith; Lim, Sungjoon

2013-04-01

This paper presents the modeling, design, fabrication, and measurement of an ultra-wideband tunable twoport resonator in which the substrate-integrated waveguide, complementary split-ring resonators (CSRRs), and varactors are embedded on the same planar platform. The tuning of the passband frequency is generated by a simple single dc voltage of 0 to 36 V, which is applied to each varactor on the CSRRs. Different capacitance values and resonant frequencies are produced while a nearly constant absolute bandwidth is maintained. The resonant frequency is varied between 0.83 and 1.58 GHz and has a wide tuning ratio of 90%.

1THz synchronous tuning of two optical synthesizers

NASA Astrophysics Data System (ADS)

Neuhaus, Rudolf; Rohde, Felix; Benkler, Erik; Puppe, Thomas; Raab, Christoph; Unterreitmayer, Reinhard; Zach, Armin; Telle, Harald R.; Stuhler, Jürgen

2016-04-01

Single-frequency optical synthesizers (SFOS) provide an optical field with arbitrarily adjustable frequency and phase which is phase-coherently linked to a reference signal. Ideally, they combine the spectral resolution of narrow linewidth frequency stabilized lasers with the broad spectral coverage of frequency combs in a tunable fashion. In state-of-the-art SFOSs tuning across comb lines requires comb line order switching,1, 2 which imposes technical overhead with problems like forbidden frequency gaps or strong phase glitches. Conventional tunable lasers often tune over only tens of GHz before mode-hops occur. Here, we present a novel type of SFOSs, which relies on a serrodyne technique with conditional flyback,3 shifting the carrier frequency of the employed frequency comb without an intrusion into the comb generator. It utilizes a new continuously tunable diode laser that tunes mode-hop-free across the full gain spectrum of the integrated laser diode. We investigate the tuning behavior of two identical SFOSs that share a common reference, by comparing the phases of their output signals. Previously, we achieved phase-stable and cycle-slip free frequency tuning over 28.1 GHz with a maximum zero-to-peak phase deviation of 62 mrad4 when sharing a common comb generator. With the new continuously tunable lasers, the SFOSs tune synchronously across nearly 17800 comb lines (1 THz). The tuning range in this approach can be extended to the full bandwidth of the frequency comb and the 110 nm mode-hop-free tuning range of the diode laser.

Fully integrated aerodynamic/dynamic optimization of helicopter rotor blades

NASA Technical Reports Server (NTRS)

Walsh, Joanne L.; Lamarsh, William J., II; Adelman, Howard M.

1992-01-01

This paper describes a fully integrated aerodynamic/dynamic optimization procedure for helicopter rotor blades. The procedure combines performance and dynamics analyses with a general purpose optimizer. The procedure minimizes a linear combination of power required (in hover, forward flight, and maneuver) and vibratory hub shear. The design variables include pretwist, taper initiation, taper ratio, root chord, blade stiffnesses, tuning masses, and tuning mass locations. Aerodynamic constraints consist of limits on power required in hover, forward flight and maneuver; airfoil section stall; drag divergence Mach number; minimum tip chord; and trim. Dynamic constraints are on frequencies, minimum autorotational inertia, and maximum blade weight. The procedure is demonstrated for two cases. In the first case the objective function involves power required (in hover, forward flight, and maneuver) and dynamics. The second case involves only hover power and dynamics. The designs from the integrated procedure are compared with designs from a sequential optimization approach in which the blade is first optimized for performance and then for dynamics. In both cases, the integrated approach is superior.

Fully integrated aerodynamic/dynamic optimization of helicopter rotor blades

NASA Technical Reports Server (NTRS)

Walsh, Joanne L.; Lamarsh, William J., II; Adelman, Howard M.

1992-01-01

A fully integrated aerodynamic/dynamic optimization procedure is described for helicopter rotor blades. The procedure combines performance and dynamic analyses with a general purpose optimizer. The procedure minimizes a linear combination of power required (in hover, forward flight, and maneuver) and vibratory hub shear. The design variables include pretwist, taper initiation, taper ratio, root chord, blade stiffnesses, tuning masses, and tuning mass locations. Aerodynamic constraints consist of limits on power required in hover, forward flight and maneuvers; airfoil section stall; drag divergence Mach number; minimum tip chord; and trim. Dynamic constraints are on frequencies, minimum autorotational inertia, and maximum blade weight. The procedure is demonstrated for two cases. In the first case, the objective function involves power required (in hover, forward flight and maneuver) and dynamics. The second case involves only hover power and dynamics. The designs from the integrated procedure are compared with designs from a sequential optimization approach in which the blade is first optimized for performance and then for dynamics. In both cases, the integrated approach is superior.

Tunable Micro- and Nanomechanical Resonators

PubMed Central

Zhang, Wen-Ming; Hu, Kai-Ming; Peng, Zhi-Ke; Meng, Guang

2015-01-01

Advances in micro- and nanofabrication technologies have enabled the development of novel micro- and nanomechanical resonators which have attracted significant attention due to their fascinating physical properties and growing potential applications. In this review, we have presented a brief overview of the resonance behavior and frequency tuning principles by varying either the mass or the stiffness of resonators. The progress in micro- and nanomechanical resonators using the tuning electrode, tuning fork, and suspended channel structures and made of graphene have been reviewed. We have also highlighted some major influencing factors such as large-amplitude effect, surface effect and fluid effect on the performances of resonators. More specifically, we have addressed the effects of axial stress/strain, residual surface stress and adsorption-induced surface stress on the sensing and detection applications and discussed the current challenges. We have significantly focused on the active and passive frequency tuning methods and techniques for micro- and nanomechanical resonator applications. On one hand, we have comprehensively evaluated the advantages and disadvantages of each strategy, including active methods such as electrothermal, electrostatic, piezoelectrical, dielectric, magnetomotive, photothermal, mode-coupling as well as tension-based tuning mechanisms, and passive techniques such as post-fabrication and post-packaging tuning processes. On the other hand, the tuning capability and challenges to integrate reliable and customizable frequency tuning methods have been addressed. We have additionally concluded with a discussion of important future directions for further tunable micro- and nanomechanical resonators. PMID:26501294

PI controller design of a wind turbine: evaluation of the pole-placement method and tuning using constrained optimization

NASA Astrophysics Data System (ADS)

Mirzaei, Mahmood; Tibaldi, Carlo; Hansen, Morten H.

2016-09-01

PI/PID controllers are the most common wind turbine controllers. Normally a first tuning is obtained using methods such as pole-placement or Ziegler-Nichols and then extensive aeroelastic simulations are used to obtain the best tuning in terms of regulation of the outputs and reduction of the loads. In the traditional tuning approaches, the properties of different open loop and closed loop transfer functions of the system are not normally considered. In this paper, an assessment of the pole-placement tuning method is presented based on robustness measures. Then a constrained optimization setup is suggested to automatically tune the wind turbine controller subject to robustness constraints. The properties of the system such as the maximum sensitivity and complementary sensitivity functions (Ms and Mt ), along with some of the responses of the system, are used to investigate the controller performance and formulate the optimization problem. The cost function is the integral absolute error (IAE) of the rotational speed from a disturbance modeled as a step in wind speed. Linearized model of the DTU 10-MW reference wind turbine is obtained using HAWCStab2. Thereafter, the model is reduced with model order reduction. The trade-off curves are given to assess the tunings of the poles- placement method and a constrained optimization problem is solved to find the best tuning.

Displacement sensor based on intra-cavity tuning of dual-frequency gas laser

NASA Astrophysics Data System (ADS)

Niu, Haisha; Niu, Yanxiong; Liu, Ning; Li, Jiyang

2018-01-01

A nanometer-resolution displacement measurement instrument based on tunable cavity frequency-splitting method is presented. One beam is split into two orthogonally polarized beams when anisotropic element inserted in the cavity. The two beams with fixed frequency difference are modulated by the movement of the reflection mirror. The changing law of the power tuning curves between the total output and the two orthogonally polarized beams is researched, and a method splitting one tuning cycle to four equal parts is proposed based on the changing law, each part corresponds to one-eighth wavelength of displacement. A laser feedback interferometer (LFI) and piezoelectric ceramic are series connected to the sensor head to calibrate the displacement that less than one-eighth wavelength. The displacement sensor achieves to afford measurement range of 20mm with resolution of 6.93nm.

Adaptation to implied tilt: extensive spatial extrapolation of orientation gradients

PubMed Central

Roach, Neil W.; Webb, Ben S.

2013-01-01

To extract the global structure of an image, the visual system must integrate local orientation estimates across space. Progress is being made toward understanding this integration process, but very little is known about whether the presence of structure exerts a reciprocal influence on local orientation coding. We have previously shown that adaptation to patterns containing circular or radial structure induces tilt-aftereffects (TAEs), even in locations where the adapting pattern was occluded. These spatially “remote” TAEs have novel tuning properties and behave in a manner consistent with adaptation to the local orientation implied by the circular structure (but not physically present) at a given test location. Here, by manipulating the spatial distribution of local elements in noisy circular textures, we demonstrate that remote TAEs are driven by the extrapolation of orientation structure over remarkably large regions of visual space (more than 20°). We further show that these effects are not specific to adapting stimuli with polar orientation structure, but require a gradient of orientation change across space. Our results suggest that mechanisms of visual adaptation exploit orientation gradients to predict the local pattern content of unfilled regions of space. PMID:23882243

Retuning the DARHT Axis-II Linear Induction Accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ekdahl, Carl August Jr.; Schulze, Martin E.; Carlson, Carl A.

2015-03-31

The Dual-Axis Radiographic Hydrodynamic Test (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. The Axis-II 1.7-kA, 1600-ns beam pulse is transported through the LIA by the magnetic field from 91 solenoids as it is accelerated to ~16.5 MeV. The magnetic field produced by the solenoids and 80 steering dipole pairs for a given set of magnet currents is known as the “tune” of the accelerator [1]. From June, 2013 through September, 2014 a single tune was used. This tune wasmore » based on measurements of LIA element positions made over several years [2], and models of solenoidal fields derived from actual field measurements [3] [4]. Based on the focus scan technique, changing the tune of the accelerator and downstream transport had no effect on the beam emittance, to within the uncertainties of the measurement. Beam sizes appear to have been overestimated in all prior measurements because of the low magnification of the imaging system. This has resulted in overestimates of emittance by ~50%. The high magnification imaging should be repeated with the old tune for direct comparison with the new tune. High magnification imaging with the new accelerator tune should be repeated after retuning the downstream to produce a much more symmetric beam to reduce the uncertainty of this measurement. Thus, these results should be considered preliminary until we can effect a new tune to produce symmetric spots at our imaging station, for high magnification images.« less

Deep learning and model predictive control for self-tuning mode-locked lasers

NASA Astrophysics Data System (ADS)

Baumeister, Thomas; Brunton, Steven L.; Nathan Kutz, J.

2018-03-01

Self-tuning optical systems are of growing importance in technological applications such as mode-locked fiber lasers. Such self-tuning paradigms require {\\em intelligent} algorithms capable of inferring approximate models of the underlying physics and discovering appropriate control laws in order to maintain robust performance for a given objective. In this work, we demonstrate the first integration of a {\\em deep learning} (DL) architecture with {\\em model predictive control} (MPC) in order to self-tune a mode-locked fiber laser. Not only can our DL-MPC algorithmic architecture approximate the unknown fiber birefringence, it also builds a dynamical model of the laser and appropriate control law for maintaining robust, high-energy pulses despite a stochastically drifting birefringence. We demonstrate the effectiveness of this method on a fiber laser which is mode-locked by nonlinear polarization rotation. The method advocated can be broadly applied to a variety of optical systems that require robust controllers.

A dual RF resonator system for high-field functional magnetic resonance imaging of small animals.

PubMed

Ludwig, R; Bodgdanov, G; King, J; Allard, A; Ferris, C F

2004-01-30

A new apparatus has been developed that integrates an animal restrainer arrangement for small animals with an actively tunable/detunable dual radio-frequency (RF) coil system for in vivo anatomical and functional magnetic resonance imaging of small animals at 4.7 T. The radio-frequency coil features an eight-element microstrip line configuration that, in conjunction with a segmented outer copper shield, forms a transversal electromagnetic (TEM) resonator structure. Matching and active tuning/detuning is achieved through fixed/variable capacitors and a PIN diode for each resonator element. These components along with radio-frequency chokes (RFCs) and blocking capacitors are placed on two printed circuit boards (PCBs) whose copper coated ground planes form the front and back of the volume coil and are therefore an integral part of the resonator structure. The magnetic resonance signal response is received with a dome-shaped single-loop surface coil that can be height-adjustable with respect to the animal's head. The conscious animal is immobilized through a mechanical arrangement that consists of a Plexiglas body tube and a head restrainer. This restrainer has a cylindrical holder with a mouthpiece and position screws to receive and restrain the head of the animal. The apparatus is intended to perform anatomical and functional magnetic resonance imaging in conscious animals such as mice, rats, hamsters, and marmosets. Cranial images acquired from fully conscious rats in a 4.7 T Bruker 40 cm bore animal scanner underscore the feasibility of this approach and bode well to extend this system to the imaging of other animals.

Frequency adjustable MEMS vibration energy harvester

NASA Astrophysics Data System (ADS)

Podder, P.; Constantinou, P.; Amann, A.; Roy, S.

2016-10-01

Ambient mechanical vibrations offer an attractive solution for powering the wireless sensor nodes of the emerging “Internet-of-Things”. However, the wide-ranging variability of the ambient vibration frequencies pose a significant challenge to the efficient transduction of vibration into usable electrical energy. This work reports the development of a MEMS electromagnetic vibration energy harvester where the resonance frequency of the oscillator can be adjusted or tuned to adapt to the ambient vibrational frequency. Micro-fabricated silicon spring and double layer planar micro-coils along with sintered NdFeB micro-magnets are used to construct the electromagnetic transduction mechanism. Furthermore, another NdFeB magnet is adjustably assembled to induce variable magnetic interaction with the transducing magnet, leading to significant change in the spring stiffness and resonance frequency. Finite element analysis and numerical simulations exhibit substantial frequency tuning range (25% of natural resonance frequency) by appropriate adjustment of the repulsive magnetic interaction between the tuning and transducing magnet pair. This demonstrated method of frequency adjustment or tuning have potential applications in other MEMS vibration energy harvesters and micromechanical oscillators.

Imaging and tuning polarity at SrTiO3 domain walls

NASA Astrophysics Data System (ADS)

Frenkel, Yiftach; Haham, Noam; Shperber, Yishai; Bell, Christopher; Xie, Yanwu; Chen, Zhuoyu; Hikita, Yasuyuki; Hwang, Harold Y.; Salje, Ekhard K. H.; Kalisky, Beena

2017-12-01

Electrostatic fields tune the ground state of interfaces between complex oxide materials. Electronic properties, such as conductivity and superconductivity, can be tuned and then used to create and control circuit elements and gate-defined devices. Here we show that naturally occurring twin boundaries, with properties that are different from their surrounding bulk, can tune the LaAlO3/SrTiO3 interface 2DEG at the nanoscale. In particular, SrTiO3 domain boundaries have the unusual distinction of remaining highly mobile down to low temperatures, and were recently suggested to be polar. Here we apply localized pressure to an individual SrTiO3 twin boundary and detect a change in LaAlO3/SrTiO3 interface current distribution. Our data directly confirm the existence of polarity at the twin boundaries, and demonstrate that they can serve as effective tunable gates. As the location of SrTiO3 domain walls can be controlled using external field stimuli, our findings suggest a novel approach to manipulate SrTiO3-based devices on the nanoscale.

Novel Electrically Tunable Microwave Solenoid Inductor and Compact Phase Shifter Utilizing Permaloy and PZT Thin Films

DOE PAGES

Wang, Tengxing; Jiang, Wei; Divan, Ralu; ...

2017-08-03

A Permalloy (Py) thin film enabled tunable 3-D solenoid inductor is designed and fabricated. The special configuration of magnetic core is discussed and by selectively patterning Py thin film, the proposed tunable inductor can work at frequency up to several GHz range. The inductance of the solenoid inductor can be electrically tuned by dc current and the tunability is above 10%. Utilizing the implemented Py enabled tunable solenoid inductor and Lead Zirconate Titanate (PZT) thin film enabled metal-insulator-metal (MIM) capacitor, a compact fully electrically tunable lumped elements phase shifter is achieved. The tunable phase shifter has both inductive and capacitivemore » tunability and the dual tunability significantly improves the tuning range and design flexibility. Moreover, the dual tunability is able to retain the equivalent characteristic impedance of the device in the process of the phase being tuned. Here, the phase of the device can be tuned by fully electrical methods and when dc current and dc voltage are provided, the length normalized phase tunability is up to 210°/cm« less

Transverse-longitudinal integrated resonator

DOEpatents

Hutchinson, Donald P [Knoxville, TN; Simpson, Marcus L [Knoxville, TN; Simpson, John T [Knoxville, TN

2003-03-11

A transverse-longitudinal integrated optical resonator (TLIR) is disclosed which includes a waveguide, a first and a second subwavelength resonant grating in the waveguide, and at least one photonic band gap resonant structure (PBG) in the waveguide. The PBG is positioned between the first and second subwavelength resonant gratings. An electro-optic waveguide material may be used to permit tuning the TLIR and to permit the TLIR to perform signal modulation and switching. The TLIR may be positioned on a bulk substrate die with one or more electronic and optical devices and may be communicably connected to the same. A method for fabricating a TLIR including fabricating a broadband reflective grating is disclosed. A method for tuning the TLIR's transmission resonance wavelength is also disclosed.

Intelligent Systems for Stabilizing Mode-Locked Lasers and Frequency Combs: Machine Learning and Equation-Free Control Paradigms for Self-Tuning Optics

NASA Astrophysics Data System (ADS)

Kutz, J. Nathan; Brunton, Steven L.

2015-12-01

We demonstrate that a software architecture using innovations in machine learning and adaptive control provides an ideal integration platform for self-tuning optics. For mode-locked lasers, commercially available optical telecom components can be integrated with servocontrollers to enact a training and execution software module capable of self-tuning the laser cavity even in the presence of mechanical and/or environmental perturbations, thus potentially stabilizing a frequency comb. The algorithm training stage uses an exhaustive search of parameter space to discover best regions of performance for one or more objective functions of interest. The execution stage first uses a sparse sensing procedure to recognize the parameter space before quickly moving to the near optimal solution and maintaining it using the extremum seeking control protocol. The method is robust and equationfree, thus requiring no detailed or quantitatively accurate model of the physics. It can also be executed on a broad range of problems provided only that suitable objective functions can be found and experimentally measured.

Continuous and reversible tuning of the disorder-driven superconductor–insulator transition in bilayer graphene

PubMed Central

Lee, Gil-Ho; Jeong, Dongchan; Park, Kee-Su; Meir, Yigal; Cha, Min-Chul; Lee, Hu-Jong

2015-01-01

The influence of static disorder on a quantum phase transition (QPT) is a fundamental issue in condensed matter physics. As a prototypical example of a disorder-tuned QPT, the superconductor–insulator transition (SIT) has been investigated intensively over the past three decades, but as yet without a general consensus on its nature. A key element is good control of disorder. Here, we present an experimental study of the SIT based on precise in-situ tuning of disorder in dual-gated bilayer graphene proximity-coupled to two superconducting electrodes through electrical and reversible control of the band gap and the charge carrier density. In the presence of a static disorder potential, Andreev-paired carriers formed close to the Fermi level in bilayer graphene constitute a randomly distributed network of proximity-induced superconducting puddles. The landscape of the network was easily tuned by electrical gating to induce percolative clusters at the onset of superconductivity. This is evidenced by scaling behavior consistent with the classical percolation in transport measurements. At lower temperatures, the solely electrical tuning of the disorder-induced landscape enables us to observe, for the first time, a crossover from classical to quantum percolation in a single device, which elucidates how thermal dephasing engages in separating the two regimes. PMID:26310774

Continuous and reversible tuning of the disorder-driven superconductor-insulator transition in bilayer graphene.

PubMed

Lee, Gil-Ho; Jeong, Dongchan; Park, Kee-Su; Meir, Yigal; Cha, Min-Chul; Lee, Hu-Jong

2015-08-27

The influence of static disorder on a quantum phase transition (QPT) is a fundamental issue in condensed matter physics. As a prototypical example of a disorder-tuned QPT, the superconductor-insulator transition (SIT) has been investigated intensively over the past three decades, but as yet without a general consensus on its nature. A key element is good control of disorder. Here, we present an experimental study of the SIT based on precise in-situ tuning of disorder in dual-gated bilayer graphene proximity-coupled to two superconducting electrodes through electrical and reversible control of the band gap and the charge carrier density. In the presence of a static disorder potential, Andreev-paired carriers formed close to the Fermi level in bilayer graphene constitute a randomly distributed network of proximity-induced superconducting puddles. The landscape of the network was easily tuned by electrical gating to induce percolative clusters at the onset of superconductivity. This is evidenced by scaling behavior consistent with the classical percolation in transport measurements. At lower temperatures, the solely electrical tuning of the disorder-induced landscape enables us to observe, for the first time, a crossover from classical to quantum percolation in a single device, which elucidates how thermal dephasing engages in separating the two regimes.

Development of testing and training simulator for CEDMCS in KSNP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nam, C. H.; Park, C. Y.; Nam, J. I.

2006-07-01

This paper presents a newly developed testing and training simulator (TTS) for automatically diagnosing and tuning the Control Element Drive Mechanism Control System (CEDMCS). TTS includes a new automatic, diagnostic, method for logic control cards and a new tuning method for phase synchronous pulse cards. In Korea Standard Nuclear Power Plants (KSNP). reactor trips occasionally occur due to a damaged logic control card in CEDMCS. However, there is no pre-diagnostic tester available to detect a damaged card in CEDMCS before it causes a reactor trip. Even after the reactor trip occurs, it is difficult to find the damaged card. Tomore » find the damaged card. ICT is usually used. ICT is an automated, computer-controlled testing system with measurement capabilities for testing active and passive components, or clusters of components, on printed circuit boards (PCB) and/or assemblies. However, ICT cannot detect a time dependent fault correctly and requires removal of the waterproof mating to perform the test. Therefore, the additional procedure of re-coating the PCB card is required after the test. TTS for CEDMCS is designed based on real plant conditions, both electrically and mechanically. Therefore, the operator can operate the Control Element Drive Mechanism (CEDM), which is mounted on the closure head of the reactor vessel (RV) using the soft control panel in ITS, which duplicates the Main Control Board (MCB) in the Main Control Room (MCR). However, during the generation of electric power in a nuclear power plant, it is difficult to operate the CEDM so a CEDM and Control Element Assembly (CEA) mock-up facility was developed to simulate a real plant CEDM. ITS was used for diagnosing and tuning control logic cards in CEDMCS in the Ulchin Nuclear Power Plant No. 4 during the plant overhaul period. It exhibited good performance in detecting the damaged cards and tuning the phase synchronous pulse cards. In addition, TTS was useful in training the CEDMCS operator by supplying detail signal information from the logic cards. (authors)« less

Tuning the Mechanical Properties of a DNA Hydrogel in Three Phases Based on ATP Aptamer.

PubMed

Liu, Hengyuan; Cao, Tianyang; Xu, Yun; Dong, Yuanchen; Liu, Dongsheng

2018-05-31

By integrating ATP aptamer into the linker DNA, a novel DNA hydrogel was designed, with mechanical properties that could be tuned into three phases. Based on the unique interaction between ATP and its aptamer, the mechanical strength of the hydrogel increased from 204 Pa to 380 Pa after adding ATP. Furthermore, with the addition of the complementary sequence to the ATP aptamer, the mechanical strength could be increased to 570 Pa.

Fine-tuning the onset of myogenesis by homeobox proteins that interact with the Myf5 limb enhancer

PubMed Central

Daubas, Philippe; Duval, Nathalie; Bajard, Lola; Langa Vives, Francina; Robert, Benoît; Mankoo, Baljinder S.; Buckingham, Margaret

2015-01-01

ABSTRACT Skeletal myogenesis in vertebrates is initiated at different sites of skeletal muscle formation during development, by activation of specific control elements of the myogenic regulatory genes. In the mouse embryo, Myf5 is the first myogenic determination gene to be expressed and its spatiotemporal regulation requires multiple enhancer sequences, extending over 120 kb upstream of the Mrf4-Myf5 locus. An enhancer, located at −57/−58 kb from Myf5, is responsible for its activation in myogenic cells derived from the hypaxial domain of the somite, that will form limb muscles. Pax3 and Six1/4 transcription factors are essential activators of this enhancer, acting on a 145-bp core element. Myogenic progenitor cells that will form the future muscle masses of the limbs express the factors necessary for Myf5 activation when they delaminate from the hypaxial dermomyotome and migrate into the forelimb bud, however they do not activate Myf5 and the myogenic programme until they have populated the prospective muscle masses. We show that Msx1 and Meox2 homeodomain-containing transcription factors bind in vitro and in vivo to specific sites in the 145-bp element, and are implicated in fine-tuning activation of Myf5 in the forelimb. Msx1, when bound between Pax and Six sites, prevents the binding of these key activators, thus inhibiting transcription of Myf5 and consequent premature myogenic differentiation. Meox2 is required for Myf5 activation at the onset of myogenesis via direct binding to other homeodomain sites in this sequence. Thus, these homeodomain factors, acting in addition to Pax3 and Six1/4, fine-tune the entry of progenitor cells into myogenesis at early stages of forelimb development. PMID:26538636

Method and apparatus for generating high power laser pulses in the two to six micron wavelength range

DOEpatents

MacPherson, David C.; Nelson, Loren D.; O'Brien, Martin J.

1996-01-01

Apparatus performs a method of generating one or more output laser pulses in a range of 2 to 6 microns. When a plurality of the output laser pulses are generated, a first output pulse has any selected wavelength within the range and a second output pulse is temporally closely spaced relative to the first output pulse and has a chosen wavelength differing from the selected wavelength. An oscillator laser cavity is provided with a tunable oscillator rod capable of generating initial laser pulses within a range of from 750 to 1000 nm, and a tuning element is coupled to the rod. A flashlamp is operable to pump the rod. For two pulse operation, the flashlamp has a given duration. A Q-switch provides the initial laser pulses upon operation of the tuning element and the flashlamp. A Raman device coupled to the rod shifts the wavelength of such initial laser pulse into the range of from 2 to 6 microns to form the output laser pulse having a wavelength within the range. For multiple pulses, a controller causes the Q-switch to provide first and second ones of the initial laser pulses, spaced by a time interval less than the given duration. Also, a selector coupled to the tuning element is operable within such duration to successively select the wavelength of the first output pulse and the chosen wavelength of the second initial pulse. The Raman device is responsive to each of the initial light pulses to generate radiation at first and second Stokes wavelengths, each of said the output laser pulses being radiation at the second Stokes wavelength.

Method and apparatus for generating high power laser pulses in the two to six micron wavelength range

DOEpatents

MacPherson, D.C.; Nelson, L.D.; O`Brien, M.J.

1996-12-10

Apparatus performs a method of generating one or more output laser pulses in a range of 2 to 6 microns. When a plurality of the output laser pulses are generated, a first output pulse has any selected wavelength within the range and a second output pulse is temporally closely spaced relative to the first output pulse and has a chosen wavelength differing from the selected wavelength. An oscillator laser cavity is provided with a tunable oscillator rod capable of generating initial laser pulses within a range of from 750 to 1000 nm, and a tuning element is coupled to the rod. A flashlamp is operable to pump the rod. For two pulse operation, the flashlamp has a given duration. A Q-switch provides the initial laser pulses upon operation of the tuning element and the flashlamp. A Raman device coupled to the rod shifts the wavelength of such initial laser pulse into the range of from 2 to 6 microns to form the output laser pulse having a wavelength within the range. For multiple pulses, a controller causes the Q-switch to provide first and second ones of the initial laser pulses, spaced by a time interval less than the given duration. Also, a selector coupled to the tuning element is operable within such duration to successively select the wavelength of the first output pulse and the chosen wavelength of the second initial pulse. The Raman device is responsive to each of the initial light pulses to generate radiation at first and second Stokes wavelengths, each of said the output laser pulses being radiation at the second Stokes wavelength. 30 figs.

Elemental Anisotropic Growth and Atomic-Scale Structure of Shape-Controlled Octahedral Pt-Ni-Co Alloy Nanocatalysts.

PubMed

Arán-Ais, Rosa M; Dionigi, Fabio; Merzdorf, Thomas; Gocyla, Martin; Heggen, Marc; Dunin-Borkowski, Rafal E; Gliech, Manuel; Solla-Gullón, José; Herrero, Enrique; Feliu, Juan M; Strasser, Peter

2015-11-11

Multimetallic shape-controlled nanoparticles offer great opportunities to tune the activity, selectivity, and stability of electrocatalytic surface reactions. However, in many cases, our synthetic control over particle size, composition, and shape is limited requiring trial and error. Deeper atomic-scale insight in the particle formation process would enable more rational syntheses. Here we exemplify this using a family of trimetallic PtNiCo nanooctahedra obtained via a low-temperature, surfactant-free solvothermal synthesis. We analyze the competition between Ni and Co precursors under coreduction "one-step" conditions when the Ni reduction rates prevailed. To tune the Co reduction rate and final content, we develop a "two-step" route and track the evolution of the composition and morphology of the particles at the atomic scale. To achieve this, scanning transmission electron microscopy and energy dispersive X-ray elemental mapping techniques are used. We provide evidence of a heterogeneous element distribution caused by element-specific anisotropic growth and create octahedral nanoparticles with tailored atomic composition like Pt1.5M, PtM, and PtM1.5 (M = Ni + Co). These trimetallic electrocatalysts have been tested toward the oxygen reduction reaction (ORR), showing a greatly enhanced mass activity related to commercial Pt/C and less activity loss than binary PtNi and PtCo after 4000 potential cycles.

Effect of Weight on the Resonant Tuning of Energy Harvesting Devices Using Giant Magnetostrictive Materials.

PubMed

Mori, Kotaro; Horibe, Tadashi; Ishikawa, Shigekazu

2018-04-10

This study deals with the numerical and experimental study of the effect of weight on the resonant tuning and energy harvesting characteristics of energy harvesting devices using giant magnetostrictive materials. The energy harvesting device is made in a cantilever shape using a thin Terfenol-D layer, stainless steel (SUS) layer and a movable proof mass, among other things. In this study, two types of movable proof mass were prepared, and the device was designed to adjust its own resonant frequency automatically to match external vibration frequency in real time. Three-dimensional finite element analysis (FEA) was performed, and the resonant frequency, tip displacement, and output voltage in the devices were predicted and measured, and the simulation and experiment results were compared. The effects of the weight of the proof mass on self-tuning ability and time-varying behavior were then considered in particular.

Viscoelastic property tuning for reducing noise radiated by switched-reluctance machines

NASA Astrophysics Data System (ADS)

Millithaler, Pierre; Dupont, Jean-Baptiste; Ouisse, Morvan; Sadoulet-Reboul, Émeline; Bouhaddi, Noureddine

2017-10-01

Switched-reluctance motors (SRM) present major acoustic drawbacks that hinder their use for electric vehicles in spite of widely-acknowledged robustness and low manufacturing costs. Unlike other types of electric machines, a SRM stator is completely encapsulated/potted with a viscoelastic resin. By taking advantage of the high damping capacity that a viscoelastic material has in certain temperature and frequency ranges, this article proposes a tuning methodology for reducing the noise emitted by a SRM in operation. After introducing the aspects the tuning process will focus on, the article details a concrete application consisting in computing representative electromagnetic excitations and then the structural response of the stator including equivalent radiated power levels. An optimised viscoelastic material is determined, with which the peak radiated levels are reduced up to 10 dB in comparison to the initial state. This methodology is implementable for concrete industrial applications as it only relies on common commercial finite-element solvers.

In situ and nonvolatile photoluminescence tuning and nanodomain writing demonstrated by all-solid-state devices based on graphene oxide.

PubMed

Tsuchiya, Takashi; Tsuruoka, Tohru; Terabe, Kazuya; Aono, Masakazu

2015-02-24

In situ and nonvolatile tuning of photoluminescence (PL) has been achieved based on graphene oxide (GO), the PL of which is receiving much attention because of various potential applications of the oxide (e.g., display, lighting, and nano-biosensor). The technique is based on in situ and nonvolatile tuning of the sp(2) domain fraction to the sp(3) domain fraction (sp(2)/sp(3) fraction) in GO through an electrochemical redox reaction achieved by solid electrolyte thin films. The all-solid-state variable PL device was fabricated by GO and proton-conducting mesoporous SiO2 thin films, which showed an extremely low PL background. The device successfully tuned the PL peak wavelength in a very wide range from 393 to 712 nm, covering that for chemically tuned GO, by adjusting the applied DC voltage within several hundred seconds. We also demonstrate the sp(2)/sp(3) fraction tuning using a conductive atomic force microscope. The device achieved not only writing, but also erasing of the sp(2)/sp(3)-fraction-tuned nanodomain (both directions operation). The combination of these techniques is applicable to a wide range of nano-optoelectronic devices including nonvolatile PL memory devices and on-demand rewritable biosensors that can be integrated into nano- and microtips which are transparent, ultrathin, flexible, and inexpensive.

Development of an Efficient CFD Model for Nuclear Thermal Thrust Chamber Assembly Design

NASA Technical Reports Server (NTRS)

Cheng, Gary; Ito, Yasushi; Ross, Doug; Chen, Yen-Sen; Wang, Ten-See

2007-01-01

The objective of this effort is to develop an efficient and accurate computational methodology to predict both detailed thermo-fluid environments and global characteristics of the internal ballistics for a hypothetical solid-core nuclear thermal thrust chamber assembly (NTTCA). Several numerical and multi-physics thermo-fluid models, such as real fluid, chemically reacting, turbulence, conjugate heat transfer, porosity, and power generation, were incorporated into an unstructured-grid, pressure-based computational fluid dynamics solver as the underlying computational methodology. The numerical simulations of detailed thermo-fluid environment of a single flow element provide a mechanism to estimate the thermal stress and possible occurrence of the mid-section corrosion of the solid core. In addition, the numerical results of the detailed simulation were employed to fine tune the porosity model mimic the pressure drop and thermal load of the coolant flow through a single flow element. The use of the tuned porosity model enables an efficient simulation of the entire NTTCA system, and evaluating its performance during the design cycle.

Selective Tuning of Gilbert Damping in Spin-Valve Trilayer by Insertion of Rare-Earth Nanolayers.

PubMed

Zhang, Wen; Zhang, Dong; Wong, Ping Kwan Johnny; Yuan, Honglei; Jiang, Sheng; van der Laan, Gerrit; Zhai, Ya; Lu, Zuhong

2015-08-12

Selective tuning of the Gilbert damping constant, α, in a NiFe/Cu/FeCo spin-valve trilayer has been achieved by inserting different rare-earth nanolayers adjacent to the ferromagnetic layers. Frequency dependent analysis of the ferromagnetic resonances shows that the initially small magnitude of α in the NiFe and FeCo layers is improved by Tb and Gd insertions to various amounts. Using the element-specific technique of X-ray magnetic circular dichroism, we find that the observed increase in α can be attributed primarily to the orbital moment enhancement of Ni and Co, rather than that of Fe. The amplitude of the enhancement depends on the specific rare-earth element, as well as on the lattice and electronic band structure of the transition metals. Our results demonstrate an effective way for individual control of the magnetization dynamics in the different layers of the spin-valve sandwich structures, which will be important for practical applications in high-frequency spintronic devices.

Laser resonance ionization spectroscopy of antimony

NASA Astrophysics Data System (ADS)

Li, R.; Lassen, J.; Ruczkowski, J.; Teigelhöfer, A.; Bricault, P.

2017-02-01

The resonant ionization laser ion source is an element selective, efficient and versatile ion source to generate radioactive ion beams at on-line mass separator facilities. For some elements with complex atomic structures and incomplete spectroscopic data, laser spectroscopic investigations are required for ionization scheme development. Laser resonance ionization spectroscopy using Ti:Sa lasers has been performed on antimony (Sb) at TRIUMF's off-line laser ion source test stand. Laser light of 230.217 nm (vacuum wavelength) as the first excitation step and light from a frequency-doubled Nd:YVO4 laser (532 nm) as the nonresonant ionization step allowed to search for suitable second excitation steps by continuous wavelength scans from 720 nm to 920 nm across the wavelength tuning range of a grating-tuned Ti:Sa laser. Upon the identification of efficient SES, the third excitation steps for resonance ionization were investigated by laser scans across Rydberg states, the ionization potential and autoionizing states. One Rydberg state and six AI states were found to be well suitable for efficient resonance ionization.

Tracking Simulation of Third-Integer Resonant Extraction for Fermilab's Mu2e Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Chong Shik; Amundson, James; Michelotti, Leo

2015-02-13

The Mu2e experiment at Fermilab requires acceleration and transport of intense proton beams in order to deliver stable, uniform particle spills to the production target. To meet the experimental requirement, particles will be extracted slowly from the Delivery Ring to the external beamline. Using Synergia2, we have performed multi-particle tracking simulations of third-integer resonant extraction in the Delivery Ring, including space charge effects, physical beamline elements, and apertures. A piecewise linear ramp profile of tune quadrupoles was used to maintain a constant averaged spill rate throughout extraction. To study and minimize beam losses, we implemented and introduced a number ofmore » features, beamline element apertures, and septum plane alignments. Additionally, the RF Knockout (RFKO) technique, which excites particles transversely, is employed for spill regulation. Combined with a feedback system, it assists in fine-tuning spill uniformity. Simulation studies were carried out to optimize the RFKO feedback scheme, which will be helpful in designing the final spill regulation system.« less

Spectrotemporal Processing in Spectral Tuning Modules of Cat Primary Auditory Cortex

PubMed Central

Atencio, Craig A.; Schreiner, Christoph E.

2012-01-01

Spectral integration properties show topographical order in cat primary auditory cortex (AI). Along the iso-frequency domain, regions with predominantly narrowly tuned (NT) neurons are segregated from regions with more broadly tuned (BT) neurons, forming distinct processing modules. Despite their prominent spatial segregation, spectrotemporal processing has not been compared for these regions. We identified these NT and BT regions with broad-band ripple stimuli and characterized processing differences between them using both spectrotemporal receptive fields (STRFs) and nonlinear stimulus/firing rate transformations. The durations of STRF excitatory and inhibitory subfields were shorter and the best temporal modulation frequencies were higher for BT neurons than for NT neurons. For NT neurons, the bandwidth of excitatory and inhibitory subfields was matched, whereas for BT neurons it was not. Phase locking and feature selectivity were higher for NT neurons. Properties of the nonlinearities showed only slight differences across the bandwidth modules. These results indicate fundamental differences in spectrotemporal preferences - and thus distinct physiological functions - for neurons in BT and NT spectral integration modules. However, some global processing aspects, such as spectrotemporal interactions and nonlinear input/output behavior, appear to be similar for both neuronal subgroups. The findings suggest that spectral integration modules in AI differ in what specific stimulus aspects are processed, but they are similar in the manner in which stimulus information is processed. PMID:22384036

Imaging spectroscopy using embedded diffractive optical arrays

NASA Astrophysics Data System (ADS)

Hinnrichs, Michele; Hinnrichs, Bradford

2017-09-01

Pacific Advanced Technology (PAT) has developed an infrared hyperspectral camera based on diffractive optic arrays. This approach to hyperspectral imaging has been demonstrated in all three infrared bands SWIR, MWIR and LWIR. The hyperspectral optical system has been integrated into the cold-shield of the sensor enabling the small size and weight of this infrared hyperspectral sensor. This new and innovative approach to an infrared hyperspectral imaging spectrometer uses micro-optics that are made up of an area array of diffractive optical elements where each element is tuned to image a different spectral region on a common focal plane array. The lenslet array is embedded in the cold-shield of the sensor and actuated with a miniature piezo-electric motor. This approach enables rapid infrared spectral imaging with multiple spectral images collected and processed simultaneously each frame of the camera. This paper will present our optical mechanical design approach which results in an infrared hyper-spectral imaging system that is small enough for a payload on a small satellite, mini-UAV, commercial quadcopter or man portable. Also, an application of how this spectral imaging technology can easily be used to quantify the mass and volume flow rates of hydrocarbon gases. The diffractive optical elements used in the lenslet array are blazed gratings where each lenslet is tuned for a different spectral bandpass. The lenslets are configured in an area array placed a few millimeters above the focal plane and embedded in the cold-shield to reduce the background signal normally associated with the optics. The detector array is divided into sub-images covered by each lenslet. We have developed various systems using a different number of lenslets in the area array. Depending on the size of the focal plane and the diameter of the lenslet array will determine the number of simultaneous different spectral images collected each frame of the camera. A 2 x 2 lenslet array will image four different spectral images of the scene each frame and when coupled with a 512 x 512 focal plane array will give spatial resolution of 256 x 256 pixel each spectral image. Another system that we developed uses a 4 x 4 lenslet array on a 1024 x 1024 pixel element focal plane array which gives 16 spectral images of 256 x 256 pixel resolution each frame. This system spans the SWIR and MWIR bands with a single optical array and focal plane array.

Tuned mass damper for integrally bladed turbine rotor

NASA Technical Reports Server (NTRS)

Marra, John J. (Inventor)

1994-01-01

The invention is directed to a damper ring for damping the natural vibration of the rotor blades of an integrally bladed rocket turbine rotor. The invention consists of an integral damper ring which is fixed to the underside of the rotor blade platform of a turbine rotor. The damper ring includes integral supports which extend radially outwardly therefrom. The supports are located adjacent to the base portion and directly under each blade of the rotor. Vibration damping is accomplished by action of tuned mass damper beams attached at each end to the supports. These beams vibrate at a predetermined frequency during operation. The vibration of the beams enforce a local node of zero vibratory amplitude at the interface between the supports and the beam. The vibration of the beams create forces upon the supports which forces are transmitted through the rotor blade mounting platform to the base of each rotor blade. When these forces attain a predetermined design frequency and magnitude and are directed to the base of the rotor blades, vibration of the rotor blades is effectively counteracted.

Sub-wavelength antenna enhanced bilayer graphene tunable photodetector

DOEpatents

Beechem, III, Thomas Edwin; Howell, Stephen W.; Peters, David W.; Davids, Paul; Ohta, Taisuke

2016-03-22

The integration of bilayer graphene with an absorption enhancing sub-wavelength antenna provides an infrared photodetector capable of real-time spectral tuning without filters at nanosecond timescales.

ATLAS I/O performance optimization in as-deployed environments

NASA Astrophysics Data System (ADS)

Maier, T.; Benjamin, D.; Bhimji, W.; Elmsheuser, J.; van Gemmeren, P.; Malon, D.; Krumnack, N.

2015-12-01

This paper provides an overview of an integrated program of work underway within the ATLAS experiment to optimise I/O performance for large-scale physics data analysis in a range of deployment environments. It proceeds to examine in greater detail one component of that work, the tuning of job-level I/O parameters in response to changes to the ATLAS event data model, and considers the implications of such tuning for a number of measures of I/O performance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ranjbar, V. H.; Méot, F.; Bai, M.

Depolarization response for a system of two orthogonal snakes at irrational tunes is studied in depth using lattice independent spin integration. Particularly, we consider the effect of overlapping spin resonances in this system, to understand the impact of phase, tune, relative location and threshold strengths of the spin resonances. Furthermore, these results are benchmarked and compared to two dimensional direct tracking results for the RHIC e-lens lattice and the standard lattice. We then consider the effect of longitudinal motion via chromatic scans using direct six dimensional lattice tracking.

Tuning maps for setpoint changes and load disturbance upsets in a three capacity process under multivariable control

NASA Technical Reports Server (NTRS)

Litt, Jonathan S.; Smith, Ira C.

1991-01-01

Tuning maps are an aid in the controller tuning process because they provide a convenient way for the plant operator to determine the consequences of adjusting different controller parameters. In this application the maps provide a graphical representation of the effect of varying the gains in the state feedback matrix on startup and load disturbance transients for a three capacity process. Nominally, the three tank system, represented in diagonal form, has a Proportional-Integral control on each loop. Cross coupling is then introduced between the loops by using non-zero off-diagonal proportional parameters. Changes in transient behavior due to setpoint and load changes are examined by varying the gains of the cross coupling terms.

A practical iterative PID tuning method for mechanical systems using parameter chart

NASA Astrophysics Data System (ADS)

Kang, M.; Cheong, J.; Do, H. M.; Son, Y.; Niculescu, S.-I.

2017-10-01

In this paper, we propose a method of iterative proportional-integral-derivative parameter tuning for mechanical systems that possibly possess hidden mechanical resonances, using a parameter chart which visualises the closed-loop characteristics in a 2D parameter space. We employ a hypothetical assumption that the considered mechanical systems have their upper limit of the derivative feedback gain, from which the feasible region in the parameter chart becomes fairly reduced and thus the gain selection can be extremely simplified. Then, a two-directional parameter search is carried out within the feasible region in order to find the best set of parameters. Experimental results show the validity of the assumption used and the proposed parameter tuning method.

Atomic-Scale Tuning of Layered Binary Metal Oxides for High Temperature Moving Assemblies

DTIC Science & Technology

2015-06-01

AFRL-OSR-VA-TR-2015-0166 Atomic-Scale Tuning of Layered Binary Metal OxideS ASHLIE MARTINI UNIVERSITY OF CALIFORNIA MERCED Final Report 06/01/2015...Assemblies 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-12-1-0221 5c.  PROGRAM ELEMENT NUMBER 6.  AUTHOR(S) ASHLIE MARTINI 5d.  PROJECT NUMBER 5e...ABSTRACT UU 18.  NUMBER        OF        PAGES 19a.  NAME OF RESPONSIBLE PERSON ASHLIE MARTINI Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18

Widely tunable chaotic fiber laser for WDM-PON detection

NASA Astrophysics Data System (ADS)

Zhang, Juan; Yang, Ling-zhen; Xu, Nai-jun; Wang, Juan-fen; Zhang, Zhao-xia; Liu, Xiang-lian

2014-05-01

A widely tunable high precision chaotic fiber laser is proposed and experimentally demonstrated. A tunable fiber Bragg grating (TFBG) filter is used as a tuning element to determine the turning range from 1533 nm to 1558 nm with a linewidth of 0.5 nm at any wavelength. The wide tuning range is capable of supporting 32 wavelength-division multiplexing (WDM) channels with 100 GHz channel spacing. All single wavelengths are found to be chaotic with 10 GHz bandwidth. The full width at half maximum (FWHM) of the chaotic correlation curve of the different wavelengths is on a picosecond time scale, thereby offering millimeter spatial resolution in WDM detection.

Tuning electronic properties in graphene quantum dots by chemical functionalization: Density functional theory calculations

NASA Astrophysics Data System (ADS)

Abdelsalam, Hazem; Elhaes, Hanan; Ibrahim, Medhat A.

2018-03-01

The energy gap and dipole moment of chemically functionalized graphene quantum dots are investigated by density functional theory. The energy gap can be tuned through edge passivation by different elements or groups. Edge passivation by oxygen considerably decreases the energy gap in hexagonal nanodots. Edge states in triangular quantum dots can also be manipulated by passivation with fluorine. The dipole moment depends on: (a) shape and edge termination of the quantum dot, (b) attached group, and (c) position to which the groups are attached. Depending on the position of attached groups, the total dipole can be increased, decreased, or eliminated.

A generalized leaky FxLMS algorithm for tuning the waterbed effect of feedback active noise control systems

NASA Astrophysics Data System (ADS)

Wu, Lifu; Qiu, Xiaojun; Guo, Yecai

2018-06-01

To tune the noise amplification in the feedback system caused by the waterbed effect effectively, an adaptive algorithm is proposed in this paper by replacing the scalar leaky factor of the leaky FxLMS algorithm with a real symmetric Toeplitz matrix. The elements in the matrix are calculated explicitly according to the noise amplification constraints, which are defined based on a simple but efficient method. Simulations in an ANC headphone application demonstrate that the proposed algorithm can adjust the frequency band of noise amplification more effectively than the FxLMS algorithm and the leaky FxLMS algorithm.

Quantum junction solar cells.

PubMed

Tang, Jiang; Liu, Huan; Zhitomirsky, David; Hoogland, Sjoerd; Wang, Xihua; Furukawa, Melissa; Levina, Larissa; Sargent, Edward H

2012-09-12

Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO(2)); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics.

Photolithography and Selective Etching of an Array of Quartz Tuning Fork Resonators with Improved Impact Resistance Characteristics

NASA Astrophysics Data System (ADS)

Lee, Sungkyu

2001-08-01

Quartz tuning fork blanks with improved impact-resistant characteristics for use in Qualcomm mobile station modem (MSM)-3000 central processing unit (CPU) chips for code division multiple access (CDMA), personal communication system (PCS), and global system for mobile communication (GSM) systems were designed using finite element method (FEM) analysis and suitable processing conditions were determined for the reproducible precision etching of a Z-cut quartz wafer into an array of tuning forks. Negative photoresist photolithography for the additive process was used in preference to positive photoresist photolithography for the subtractive process to etch the array of quartz tuning forks. The tuning fork pattern was transferred via a conventional photolithographical chromium/quartz glass template using a standard single-sided aligner and subsequent negative photoresist development. A tightly adhering and pinhole-free 600/2000 Å chromium/gold mask was coated over the developed photoresist pattern which was subsequently stripped in acetone. This procedure was repeated on the back surface of the wafer. With the protective metallization area of the tuning fork geometry thus formed, etching through the quartz wafer was performed at 80°C in a ± 1.5°C controlled bath containing a concentrated solution of ammonium bifluoride to remove the unwanted areas of the quartz wafer. The quality of the quartz wafer surface finish after quartz etching depended primarily on the surface finish of the quartz wafer prior to etching and the quality of quartz crystals used. Selective etching of a 100 μm quartz wafer could be achieved within 90 min at 80°C. A selective etching procedure with reproducible precision has thus been established and enables the photolithographic mass production of miniature tuning fork resonators.

Application of IFT and SPSA to servo system control.

PubMed

Rădac, Mircea-Bogdan; Precup, Radu-Emil; Petriu, Emil M; Preitl, Stefan

2011-12-01

This paper treats the application of two data-based model-free gradient-based stochastic optimization techniques, i.e., iterative feedback tuning (IFT) and simultaneous perturbation stochastic approximation (SPSA), to servo system control. The representative case of controlled processes modeled by second-order systems with an integral component is discussed. New IFT and SPSA algorithms are suggested to tune the parameters of the state feedback controllers with an integrator in the linear-quadratic-Gaussian (LQG) problem formulation. An implementation case study concerning the LQG-based design of an angular position controller for a direct current servo system laboratory equipment is included to highlight the pros and cons of IFT and SPSA from an application's point of view. The comparison of IFT and SPSA algorithms is focused on an insight into their implementation.

Velocity control of servo systems using an integral retarded algorithm.

PubMed

Ramírez, Adrián; Garrido, Rubén; Mondié, Sabine

2015-09-01

This paper presents a design technique for the delay-based controller called Integral Retarded (IR), and its applications to velocity control of servo systems. Using spectral analysis, the technique yields a tuning strategy for the IR by assigning a triple real dominant root for the closed-loop system. This result ultimately guarantees a desired exponential decay rate σ(d) while achieving the IR tuning as explicit function of σ(d) and system parameters. The intentional introduction of delay allows using noisy velocity measurements without additional filtering. The structure of the controller is also able to avoid velocity measurements by using instead position information. The IR is compared to a classical PI, both tested in a laboratory prototype. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Tunable optical analog to electromagnetically induced transparency in graphene-ring resonators system.

PubMed

Wang, Yonghua; Xue, Chenyang; Zhang, Zengxing; Zheng, Hua; Zhang, Wendong; Yan, Shubin

2016-12-12

The analogue of electromagnetically induced transparency in optical ways has shown great potential in optical delay and quantum-information technology due to its flexible design and easy implementation. The chief drawback for these devices is the bad tunability. Here we demonstrate a tunable optical transparency system formed by graphene-silicon microrings which could control the transparent window by electro-optical means. The device consists of cascaded coupled ring resonators and a graphene/graphene capacitor which integrated on one of the rings. By tuning the Fermi level of the graphene sheets, we can modulate the round-trip ring loss so that the transparency window can be dynamically tuned. The results provide a new method for the manipulation and transmission of light in highly integrated optical circuits and quantum information storage devices.

Tailoring entanglement through domain engineering in a lithium niobate waveguide

PubMed Central

Ming, Yang; Tan, Ai-Hong; Wu, Zi-Jian; Chen, Zhao-Xian; Xu, Fei; Lu, Yan-Qing

2014-01-01

We propose to integrate the electro-optic (EO) tuning function into on-chip domain engineered lithium niobate (LN) waveguide. Due to the versatility of LN, both the spontaneously parametric down conversion (SPDC) and EO interaction could be realized simultaneously. Photon pairs are generated through SPDC, and the formation of entangled state is modulated by EO processes. An EO tunable polarization-entangled photon state is proposed. Orthogonally-polarized and parallel-polarized entanglements of photon pairs are instantly switchable by tuning the applied field. The characteristics of the source are theoretically investigated showing adjustable bandwidths and high entanglement degrees. Moreover, other kinds of reconfigurable entanglement are also achievable based on suitable domain-design. We believe tailoring entanglement based on domain engineering is a very promising solution for next generation function-integrated quantum circuits. PMID:24770555

[Particle pollution effects on the risk of cardiovascular diseases].

PubMed

Massamba, V K; Coppieters, Y; Mercier, G; Collart, P; Levêque, A

2014-02-01

The effects of air pollution on health are quite well-documented and the influence of particulate pollution on morbidity and mortality from myocardial infarction and stroke is increasingly evident. The objective of this literature review is to identify and synthesize articles on the impact of air pollution by PM10 and PM2.5 of myocardial infarction and stroke. A total of 14 studies were reported on the effects of PM10 and five on the effects of PM2.5. Nine out of 14 studies for PM10 and two studies of five for PM2.5 have found a significant association with myocardial infarction and/or stroke. Particle composition according to location, study period and population must be considered in interpreting the results on the health effects of air pollution. The integration of these elements is important for decision making in tune with social and economic conditions specific to each environment. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Tunable Fano resonance in MDM stub waveguide coupled with a U-shaped cavity

NASA Astrophysics Data System (ADS)

Yi, Xingchun; Tian, Jinping; Yang, Rongcao

2018-04-01

A new compact metal-dielectric-metal waveguide system consisting of a stub coupled with a U-cavity is proposed to produce sharp and asymmetric Fano resonance. The transmission properties of the proposed structure are numerically studied by the finite element method and verified by the coupled mode theory. Simulation results reveal that the spectral profile can be easily tuned by adjusting the geometric parameters of the structure. One of the potential application of the proposed structure as a highly efficient plasmonic refractive index nanosensor was investigated with its sensitivity of more than 1000 nm/RIU and a figure of merit of up to 5500. Another application is integrated slow-light device whose group index can be greater than 6. In addition, multiple Fano resonances will occur in the broadband transmission spectrum by adding another U-cavity or (and) stub. The characteristics of the proposed structure are very promising for the highly performance filters, on-chip nanosensors, and slow-light devices.

A kirigami approach to engineering elasticity in nanocomposites through patterned defects.

PubMed

Shyu, Terry C; Damasceno, Pablo F; Dodd, Paul M; Lamoureux, Aaron; Xu, Lizhi; Shlian, Matthew; Shtein, Max; Glotzer, Sharon C; Kotov, Nicholas A

2015-08-01

Efforts to impart elasticity and multifunctionality in nanocomposites focus mainly on integrating polymeric and nanoscale components. Yet owing to the stochastic emergence and distribution of strain-concentrating defects and to the stiffening of nanoscale components at high strains, such composites often possess unpredictable strain-property relationships. Here, by taking inspiration from kirigami—the Japanese art of paper cutting—we show that a network of notches made in rigid nanocomposite and other composite sheets by top-down patterning techniques prevents unpredictable local failure and increases the ultimate strain of the sheets from 4 to 370%. We also show that the sheets' tensile behaviour can be accurately predicted through finite-element modelling. Moreover, in marked contrast to other stretchable conductors, the electrical conductance of the stretchable kirigami sheets is maintained over the entire strain regime, and we demonstrate their use to tune plasma-discharge phenomena. The unique properties of kirigami nanocomposites as plasma electrodes open up a wide range of novel technological solutions for stretchable electronics and optoelectronic devices, among other application possibilities.

Discriminator Stabilized Superconductor/Ferroelectric Thin Film Local Oscillator

NASA Technical Reports Server (NTRS)

Romanofsky, Robert R. (Inventor); Miranda, Felix A. (Inventor)

2000-01-01

A tunable local oscillator with a tunable circuit that includes a resonator and a transistor as an active element for oscillation. Tuning of the circuit is achieved with an externally applied dc bias across coupled lines on the resonator. Preferably the resonator is a high temperature superconductor microstrip ring resonator with integral coupled lines formed over a thin film ferroelectric material. A directional coupler samples the output of the oscillator which is fed into a diplexer for determining whether the oscillator is performing at a desired frequency. The high-pass and lowpass outputs of the diplexer are connected to diodes respectively for inputting the sampled signals into a differential operational amplifier. The amplifier compares the sampled signals and emits an output signal if there is a difference between the resonant and crossover frequencies. Based on the sampled signal, a bias supplied to the ring resonator is either increased or decreased for raising or lowering the resonant frequency by decreasing or increasing, respectively, the dielectric constant of the ferroelectric.

Open loop, auto reversing liquid nitrogen circulation thermal system for thermo vacuum chamber

NASA Astrophysics Data System (ADS)

Naidu, M. C. A.; Nolakha, Dinesh; Saharkar, B. S.; Kavani, K. M.; Patel, D. R.

2012-11-01

In a thermo vacuum chamber, attaining and controlling low and high temperatures (-100 Deg. C to +120 Deg. C) is a very important task. This paper describes the development of "Open loop, auto reversing liquid nitrogen based thermal system". System specifications, features, open loop auto reversing system, liquid nitrogen flow paths etc. are discussed in this paper. This thermal system consists of solenoid operated cryogenic valves, double embossed thermal plate (shroud), heating elements, temperature sensors and PLC. Bulky items like blowers, heating chambers, liquid nitrogen injection chambers, huge pipe lines and valves were not used. This entire thermal system is very simple to operate and PLC based, fully auto system with auto tuned to given set temperatures. This system requires a very nominal amount of liquid nitrogen (approx. 80 liters / hour) while conducting thermo vacuum tests. This system was integrated to 1.2m dia thermo vacuum chamber, as a part of its augmentation, to conduct extreme temperature cycling tests on passive antenna reflectors of satellites.

Simulations of anti-parallel reconnection using a nonlocal heat flux closure

DOE PAGES

Ng, Jonathan; Hakim, Ammar; Bhattacharjee, A.; ...

2017-08-08

The integration of kinetic effects in fluid models is important for global simulations of the Earth's magnetosphere. In particular, it has been shown that ion kinetics play a crucial role in the dynamics of large reconnecting systems, and that higher-order fluid moment models can account for some of these effects. Here, we use a ten-moment model for electrons and ions, which includes the off diagonal elements of the pressure tensor that are important for magnetic reconnection. Kinetic effects are recovered by using a nonlocal heat flux closure, which approximates linear Landau damping in the fluid framework. Moreover, the closure ismore » tested using the island coalescence problem, which is sensitive to ion dynamics. We also demonstrate that the nonlocal closure is able to self-consistently reproduce the structure of the ion diffusion region, pressure tensor, and ion velocity without the need for fine-tuning of relaxation coefficients present in earlier models.« less

Combinatorial Screening for Transgenic Yeasts with High Cellulase Activities in Combination with a Tunable Expression System

PubMed Central

Ito, Yoichiro; Yamanishi, Mamoru; Ikeuchi, Akinori; Imamura, Chie; Matsuyama, Takashi

2015-01-01

Combinatorial screening used together with a broad library of gene expression cassettes is expected to produce a powerful tool for the optimization of the simultaneous expression of multiple enzymes. Recently, we proposed a highly tunable protein expression system that utilized multiple genome-integrated target genes to fine-tune enzyme expression in yeast cells. This tunable system included a library of expression cassettes each composed of three gene-expression control elements that in different combinations produced a wide range of protein expression levels. In this study, four gene expression cassettes with graded protein expression levels were applied to the expression of three cellulases: cellobiohydrolase 1, cellobiohydrolase 2, and endoglucanase 2. After combinatorial screening for transgenic yeasts simultaneously secreting these three cellulases, we obtained strains with higher cellulase expressions than a strain harboring three cellulase-expression constructs within one high-performance gene expression cassette. These results show that our method will be of broad use throughout the field of metabolic engineering. PMID:26692026

Neural integrators for decision making: a favorable tradeoff between robustness and sensitivity

PubMed Central

Cain, Nicholas; Barreiro, Andrea K.; Shadlen, Michael

2013-01-01

A key step in many perceptual decision tasks is the integration of sensory inputs over time, but a fundamental questions remain about how this is accomplished in neural circuits. One possibility is to balance decay modes of membranes and synapses with recurrent excitation. To allow integration over long timescales, however, this balance must be exceedingly precise. The need for fine tuning can be overcome via a “robust integrator” mechanism in which momentary inputs must be above a preset limit to be registered by the circuit. The degree of this limiting embodies a tradeoff between sensitivity to the input stream and robustness against parameter mistuning. Here, we analyze the consequences of this tradeoff for decision-making performance. For concreteness, we focus on the well-studied random dot motion discrimination task and constrain stimulus parameters by experimental data. We show that mistuning feedback in an integrator circuit decreases decision performance but that the robust integrator mechanism can limit this loss. Intriguingly, even for perfectly tuned circuits with no immediate need for a robustness mechanism, including one often does not impose a substantial penalty for decision-making performance. The implication is that robust integrators may be well suited to subserve the basic function of evidence integration in many cognitive tasks. We develop these ideas using simulations of coupled neural units and the mathematics of sequential analysis. PMID:23446688

Integrated transient thermal-structural finite element analysis

NASA Technical Reports Server (NTRS)

Thornton, E. A.; Dechaumphai, P.; Wieting, A. R.; Tamma, K. K.

1981-01-01

An integrated thermal structural finite element approach for efficient coupling of transient thermal and structural analysis is presented. Integrated thermal structural rod and one dimensional axisymmetric elements considering conduction and convection are developed and used in transient thermal structural applications. The improved accuracy of the integrated approach is illustrated by comparisons with exact transient heat conduction elasticity solutions and conventional finite element thermal finite element structural analyses.

Carotid chemoreceptors tune breathing via multipath routing: reticular chain and loop operations supported by parallel spike train correlations.

PubMed

Morris, Kendall F; Nuding, Sarah C; Segers, Lauren S; Iceman, Kimberly E; O'Connor, Russell; Dean, Jay B; Ott, Mackenzie M; Alencar, Pierina A; Shuman, Dale; Horton, Kofi-Kermit; Taylor-Clark, Thomas E; Bolser, Donald C; Lindsey, Bruce G

2018-02-01

We tested the hypothesis that carotid chemoreceptors tune breathing through parallel circuit paths that target distinct elements of an inspiratory neuron chain in the ventral respiratory column (VRC). Microelectrode arrays were used to monitor neuronal spike trains simultaneously in the VRC, peri-nucleus tractus solitarius (p-NTS)-medial medulla, the dorsal parafacial region of the lateral tegmental field (FTL-pF), and medullary raphe nuclei together with phrenic nerve activity during selective stimulation of carotid chemoreceptors or transient hypoxia in 19 decerebrate, neuromuscularly blocked, and artificially ventilated cats. Of 994 neurons tested, 56% had a significant change in firing rate. A total of 33,422 cell pairs were evaluated for signs of functional interaction; 63% of chemoresponsive neurons were elements of at least one pair with correlational signatures indicative of paucisynaptic relationships. We detected evidence for postinspiratory neuron inhibition of rostral VRC I-Driver (pre-Bötzinger) neurons, an interaction predicted to modulate breathing frequency, and for reciprocal excitation between chemoresponsive p-NTS neurons and more downstream VRC inspiratory neurons for control of breathing depth. Chemoresponsive pericolumnar tonic expiratory neurons, proposed to amplify inspiratory drive by disinhibition, were correlationally linked to afferent and efferent "chains" of chemoresponsive neurons extending to all monitored regions. The chains included coordinated clusters of chemoresponsive FTL-pF neurons with functional links to widespread medullary sites involved in the control of breathing. The results support long-standing concepts on brain stem network architecture and a circuit model for peripheral chemoreceptor modulation of breathing with multiple circuit loops and chains tuned by tegmental field neurons with quasi-periodic discharge patterns. NEW & NOTEWORTHY We tested the long-standing hypothesis that carotid chemoreceptors tune the frequency and depth of breathing through parallel circuit operations targeting the ventral respiratory column. Responses to stimulation of the chemoreceptors and identified functional connectivity support differential tuning of inspiratory neuron burst duration and firing rate and a model of brain stem network architecture incorporating tonic expiratory "hub" neurons regulated by convergent neuronal chains and loops through rostral lateral tegmental field neurons with quasi-periodic discharge patterns.

Astronomical tunings of the Oligocene-Miocene transition from Pacific Ocean Site U1334 and implications for the carbon cycle

NASA Astrophysics Data System (ADS)

Beddow, Helen M.; Liebrand, Diederik; Wilson, Douglas S.; Hilgen, Frits J.; Sluijs, Appy; Wade, Bridget S.; Lourens, Lucas J.

2018-03-01

Astronomical tuning of sediment sequences requires both unambiguous cycle pattern recognition in climate proxy records and astronomical solutions, as well as independent information about the phase relationship between these two. Here we present two different astronomically tuned age models for the Oligocene-Miocene transition (OMT) from Integrated Ocean Drilling Program Site U1334 (equatorial Pacific Ocean) to assess the effect tuning has on astronomically calibrated ages and the geologic timescale. These alternative age models (roughly from ˜ 22 to ˜ 24 Ma) are based on different tunings between proxy records and eccentricity: the first age model is based on an aligning CaCO3 weight (wt%) to Earth's orbital eccentricity, and the second age model is based on a direct age calibration of benthic foraminiferal stable carbon isotope ratios (δ13C) to eccentricity. To independently test which tuned age model and associated tuning assumptions are in best agreement with independent ages based on tectonic plate-pair spreading rates, we assign the tuned ages to magnetostratigraphic reversals identified in deep-marine magnetic anomaly profiles. Subsequently, we compute tectonic plate-pair spreading rates based on the tuned ages. The resultant alternative spreading-rate histories indicate that the CaCO3 tuned age model is most consistent with a conservative assumption of constant, or linearly changing, spreading rates. The CaCO3 tuned age model thus provides robust ages and durations for polarity chrons C6Bn.1n-C7n.1r, which are not based on astronomical tuning in the latest iteration of the geologic timescale. Furthermore, it provides independent evidence that the relatively large (several 10 000 years) time lags documented in the benthic foraminiferal isotope records relative to orbital eccentricity constitute a real feature of the Oligocene-Miocene climate system and carbon cycle. The age constraints from Site U1334 thus indicate that the delayed responses of the Oligocene-Miocene climate-cryosphere system and (marine) carbon cycle resulted from highly non-linear feedbacks to astronomical forcing.

In Situ Electrochemical Oxidation Tuning of Transition Metal Disulfides to Oxides for Enhanced Water Oxidation

DOE PAGES

Chen, Wei; Wang, Haotian; Li, Yuzhang; ...

2015-07-15

The development of catalysts with earth-abundant elements for efficient oxygen evolution reactions is of paramount significance for clean and sustainable energy storage and conversion devices. Our group demonstrated recently that the electrochemical tuning of catalysts via lithium insertion and extraction has emerged as a powerful approach to improve catalytic activity. Here we report a novel in situ electrochemical oxidation tuning approach to develop a series of binary, ternary, and quaternary transition metal (e.g., Co, Ni, Fe) oxides from their corresponding sulfides as highly active catalysts for much enhanced water oxidation. The electrochemically tuned cobalt–nickel–iron oxides grown directly on the three-dimensionalmore » carbon fiber electrodes exhibit a low overpotential of 232 mV at current density of 10 mA cm –2, small Tafel slope of 37.6 mV dec –1, and exceptional long-term stability of electrolysis for over 100 h in 1 M KOH alkaline medium, superior to most non-noble oxygen evolution catalysts reported so far. The materials evolution associated with the electrochemical oxidation tuning is systematically investigated by various characterizations, manifesting that the improved activities are attributed to the significant grain size reduction and increase of surface area and electroactive sites. This work provides a promising strategy to develop electrocatalysts for large-scale water-splitting systems and many other applications.« less

Integrated Prevention of Social Dependencies in Adolescents through the Scenario Method

ERIC Educational Resources Information Center

Maznichenko, Marina A.; Neskoromnykh, Nataliya I.

2015-01-01

This article provides a rationale for the need to take an integrated approach to prevention of social dependencies in adolescents. Through this approach, the authors fine-tune the determination of the phenomenon of prevention of social dependencies. The authors bring to light the potential of the scenario method in resolving the above objective.…

The Weight of Time: Affordances for an Integrated Magnitude System

ERIC Educational Resources Information Center

Lu, Aitao; Mo, Lei; Hodges, Bert H.

2011-01-01

In five experiments we explored the effects of weight on time in different action contexts to test the hypothesis that an integrated magnitude system is tuned to affordances. Larger magnitudes generally seem longer; however, Lu and colleagues (2009) found that if numbers were presented as weights in a range heavy enough to affect lifting, the…

Compact GaSb/silicon-on-insulator 2.0x μm widely tunable external cavity lasers.

PubMed

Wang, Ruijun; Malik, Aditya; Šimonytė, Ieva; Vizbaras, Augustinas; Vizbaras, Kristijonas; Roelkens, Gunther

2016-12-12

2.0x µm widely tunable external cavity lasers realized by combining a GaSb gain chip with a silicon photonics waveguide circuit for wavelength selection are demonstrated. Wavelength tuning over 58 nm from 2.01 to 2.07 µm is demonstrated. In the silicon photonic integrated circuit, laser feedback is realized by using a silicon Bragg grating and continuous tuning is realized by using two thermally tuned silicon microring resonators (MRRs) and a phase section. The uncooled laser has maximum output power of 7.5 mW and threshold current density of 0.8 kA/cm². The effect of the coupling gap of the MRRs on tunable laser performance is experimentally assessed. A side mode suppression ratio better than 52 dB over the full tuning range and in the optimum operation point of more than 60 dB is achieved for the laser with weakly coupled MRRs.

A multiple degree of freedom electromechanical Helmholtz resonator.

PubMed

Liu, Fei; Horowitz, Stephen; Nishida, Toshikazu; Cattafesta, Louis; Sheplak, Mark

2007-07-01

The development of a tunable, multiple degree of freedom (MDOF) electromechanical Helmholtz resonator (EMHR) is presented. An EMHR consists of an orifice, backing cavity, and a compliant piezoelectric composite diaphragm. Electromechanical tuning of the acoustic impedance is achieved via passive electrical networks shunted across the piezoceramic. For resistive and capacitive loads, the EMHR is a 2DOF system possessing one acoustic and one mechanical DOF. When inductive ladder networks are employed, multiple electrical DOF are added. The dynamics of the multi-energy domain system are modeled using lumped elements and are represented in an equivalent electrical circuit, which is used to analyze the tunable acoustic input impedance of the EMHR. The two-microphone method is used to measure the acoustic impedance of two EMHR designs with a variety of resistive, capacitive, and inductive shunts. For the first design, the data demonstrate that the tuning range of the second resonant frequency for an EMHR with non-inductive shunts is limited by short- and open-circuit conditions, while an inductive shunt results in a 3DOF system possessing an enhanced tuning range. The second design achieves stronger coupling between the Helmholtz resonator and the piezoelectric backplate, and both resonant frequencies can be tuned with different non-inductive loads.

Imaging and tuning polarity at SrTiO 3 domain walls

DOE PAGES

Frenkel, Yiftach; Haham, Noam; Shperber, Yishai; ...

2017-09-18

Electrostatic fields tune the ground state of interfaces between complex oxide materials. Electronic properties, such as conductivity and superconductivity, can be tuned and then used to create and control circuit elements and gate-defined devices. Here in this paper, we show that naturally occurring twin boundaries, with properties that are different from their surrounding bulk, can tune the LaAlO 3/SrTiO 3 interface 2DEG at the nanoscale. In particular, SrTiO 3 domain boundaries have the unusual distinction of remaining highly mobile down to low temperatures, and were recently suggested to be polar. Here we apply localized pressure to an individual SrTiO 3more » twin boundary and detect a change in LaAlO 3/SrTiO 3 interface current distribution. Our data directly confirm the existence of polarity at the twin boundaries, and demonstrate that they can serve as effective tunable gates. As the location of SrTiO 3 domain walls can be controlled using external field stimuli, our findings suggest a novel approach to manipulate SrTiO 3-based devices on the nanoscale.« less

Cyto-molecular Tuning of Quantum Dots

NASA Astrophysics Data System (ADS)

Lee, Bong; Suresh, Sindhuja; Ekpenyong, Andrew

Quantum dots (QDs) are semiconductor nanoparticles composed of groups II-VI or III-V elements, with physical dimensions smaller than the exciton Bohr radius, and between 1-10 nm. Their applications and promising myriad applications in photovoltaic cells, biomedical imaging, targeted drug delivery, quantum computing, etc, have led to much research on their interactions with other systems. For biological systems, research has focused on biocompatibility and cytotoxicity of QDs in the context of imaging/therapy. However, there is a paucity of work on how biological systems might be used to tune QDs. Here, we hypothesize that the photo-electronic properties of QDs can be tuned by biological macromolecules following controlled changes in cellular activities. Using CdSe/ZnS core-shell QDs, we perform spectroscopic analysis of optically excited colloidal QDs with and without promyelocytic HL60 cells. Preliminary results show shifts in the emission spectra of the colloidal dispersions with and without cells. We will present results for activated HL60-derived cells where specific macromolecules produced by these cells perturb the electric dipole moments of the excited QDs and the associated electric fields, in ways that constitute what we describe as cyto-molecular tuning. Startup funds from the College of Arts and Sciences, Creighton University (to AEE).

Simulation and Implementation of a Morphology-Tuned Gold Nano-Islands Integrated Plasmonic Sensor

PubMed Central

Ozhikandathil, Jayan; Packirisamy, Muthukumaran

2014-01-01

This work presents simulation, analysis and implementation of morphology tuning of gold nano-island structures deposited by a novel convective assembly technique. The gold nano-islands were simulated using 3D Finite-Difference Time-Domain (FDTD) techniques to investigate the effect of morphological changes and adsorption of protein layers on the localized surface plasmon resonance (LSPR) properties. Gold nano-island structures were deposited on glass substrates by a novel and low-cost convective assembly process. The structure formed by an uncontrolled deposition method resulted in a nano-cluster morphology, which was annealed at various temperatures to tune the optical absorbance properties by transforming the nano-clusters to a nano-island morphology by modifying the structural shape and interparticle separation distances. The dependence of the size and the interparticle separation distance of the nano-islands on the LSPR properties were analyzed in the simulation. The effect of adsorption of protein layer on the nano-island structures was simulated and a relation between the thickness and the refractive index of the protein layer on the LSPR peak was presented. Further, the sensitivity of the gold nano-island integrated sensor against refractive index was computed and compared with the experimental results. PMID:24932868

The Temporal Tuning of the Drosophila Motion Detectors Is Determined by the Dynamics of Their Input Elements.

PubMed

Arenz, Alexander; Drews, Michael S; Richter, Florian G; Ammer, Georg; Borst, Alexander

2017-04-03

Detecting the direction of motion contained in the visual scene is crucial for many behaviors. However, because single photoreceptors only signal local luminance changes, motion detection requires a comparison of signals from neighboring photoreceptors across time in downstream neuronal circuits. For signals to coincide on readout neurons that thus become motion and direction selective, different input lines need to be delayed with respect to each other. Classical models of motion detection rely on non-linear interactions between two inputs after different temporal filtering. However, recent studies have suggested the requirement for at least three, not only two, input signals. Here, we comprehensively characterize the spatiotemporal response properties of all columnar input elements to the elementary motion detectors in the fruit fly, T4 and T5 cells, via two-photon calcium imaging. Between these input neurons, we find large differences in temporal dynamics. Based on this, computer simulations show that only a small subset of possible arrangements of these input elements maps onto a recently proposed algorithmic three-input model in a way that generates a highly direction-selective motion detector, suggesting plausible network architectures. Moreover, modulating the motion detection system by octopamine-receptor activation, we find the temporal tuning of T4 and T5 cells to be shifted toward higher frequencies, and this shift can be fully explained by the concomitant speeding of the input elements. Copyright © 2017 Elsevier Ltd. All rights reserved.

A novel auto-tuning PID control mechanism for nonlinear systems.

PubMed

Cetin, Meric; Iplikci, Serdar

2015-09-01

In this paper, a novel Runge-Kutta (RK) discretization-based model-predictive auto-tuning proportional-integral-derivative controller (RK-PID) is introduced for the control of continuous-time nonlinear systems. The parameters of the PID controller are tuned using RK model of the system through prediction error-square minimization where the predicted information of tracking error provides an enhanced tuning of the parameters. Based on the model-predictive control (MPC) approach, the proposed mechanism provides necessary PID parameter adaptations while generating additive correction terms to assist the initially inadequate PID controller. Efficiency of the proposed mechanism has been tested on two experimental real-time systems: an unstable single-input single-output (SISO) nonlinear magnetic-levitation system and a nonlinear multi-input multi-output (MIMO) liquid-level system. RK-PID has been compared to standard PID, standard nonlinear MPC (NMPC), RK-MPC and conventional sliding-mode control (SMC) methods in terms of control performance, robustness, computational complexity and design issue. The proposed mechanism exhibits acceptable tuning and control performance with very small steady-state tracking errors, and provides very short settling time for parameter convergence. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

A simple attitude control of quadrotor helicopter based on Ziegler-Nichols rules for tuning PD parameters.

PubMed

He, ZeFang; Zhao, Long

2014-01-01

An attitude control strategy based on Ziegler-Nichols rules for tuning PD (proportional-derivative) parameters of quadrotor helicopters is presented to solve the problem that quadrotor tends to be instable. This problem is caused by the narrow definition domain of attitude angles of quadrotor helicopters. The proposed controller is nonlinear and consists of a linear part and a nonlinear part. The linear part is a PD controller with PD parameters tuned by Ziegler-Nichols rules and acts on the quadrotor decoupled linear system after feedback linearization; the nonlinear part is a feedback linearization item which converts a nonlinear system into a linear system. It can be seen from the simulation results that the attitude controller proposed in this paper is highly robust, and its control effect is better than the other two nonlinear controllers. The nonlinear parts of the other two nonlinear controllers are the same as the attitude controller proposed in this paper. The linear part involves a PID (proportional-integral-derivative) controller with the PID controller parameters tuned by Ziegler-Nichols rules and a PD controller with the PD controller parameters tuned by GA (genetic algorithms). Moreover, this attitude controller is simple and easy to implement.

25Gb/s 1V-driving CMOS ring modulator with integrated thermal tuning.

PubMed

Li, Guoliang; Zheng, Xuezhe; Yao, Jin; Thacker, Hiren; Shubin, Ivan; Luo, Ying; Raj, Kannan; Cunningham, John E; Krishnamoorthy, Ashok V

2011-10-10

We report a high-speed ring modulator that fits many of the ideal qualities for optical interconnect in future exascale supercomputers. The device was fabricated in a 130 nm SOI CMOS process, with 7.5 μm ring radius. Its high-speed section, employing PN junction that works at carrier-depletion mode, enables 25 Gb/s modulation and an extinction ratio >5 dB with only 1V peak-to-peak driving. Its thermal tuning section allows the device to work in broad wavelength range, with a tuning efficiency of 0.19 nm/mW. Based on microwave characterization and circuit modeling, the modulation energy is estimated ~7 fJ/bit. The whole device fits in a compact 400 μm2 footprint.

Customised spatiotemporal temperature gradients created by a liquid metal enabled vortex generator.

PubMed

Zhu, Jiu Yang; Thurgood, Peter; Nguyen, Ngan; Ghorbani, Kamran; Khoshmanesh, Khashayar

2017-11-07

Generating customised temperature gradients in miniaturised flow-free liquid chambers is challenging due to the dominance of diffusion. Inducing internal flows in the form of vortices is an effective strategy for overcoming the limitations of diffusion in such environments. Vortices can be produced by applying pressure, temperature and electric potential gradients via miniaturised actuators. However, the difficulties associated with the fabrication, integration, maintenance and operation of such actuators hinder their utility. Here, we utilise liquid metal enabled pumps to induce vortices inside a miniaturised liquid chamber. The configuration and rotational velocity of these vortices can be controlled by tuning the polarity and frequency of the energising electrical signal. This allows creation of customised spatial temperature gradients inside the chamber. The absence of conventional moving elements in the pumps facilitates the rapid reconfiguration of vortices. This enables quick transition from one temperature profile to another, and creates customised spatiotemporal temperature gradients. This allows temperature oscillation from 35 to 62 °C at the hot spot, and from 25 to 27 °C at the centre of the vortex within 15 seconds. Our liquid metal enabled vortex generator can be fabricated, integrated and operated easily, and offers opportunities for studying thermo-responsive materials and biological samples.

Tuning the Curie temperature of L 1 0 ordered FePt thin films through site-specific substitution of Rh

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Dongbin; Sun, Cheng-Jun; Chen, Jing-Sheng

2014-10-14

In structurally ordered magnetic thin films, the Curie temperature (TC) of ferromagnetic films depends on the exchange integral of the short range ordered neighboring atoms. The exchange integral may be adjusted by controlling elemental substitutional concentration at the lattice site of interest. We show how to control the TC in high anisotropy L10 Fe50Pt50 magnetic thin films by substituting Rh into the Pt site. Rh substitution in L10 FePt modified the local atomic environment and corresponding electronic properties while retaining the ordered L10 phase. The analysis of extended x-ray Absorption Fine Structure (EXAFS) spectra shows that Rh uniformly substitutes formore » Pt in L10 FePt. With 15 at. % of Rh substitution, temperature-dependent magnetic measurements show that the saturation magnetization (Ms) decreases from 1152 emu/cc to 670 emu/cc, the magnetocrystalline anisotropy (Ku) drops from 5×107 erg/cc to 2×107 erg/cc, and TC decreased from 750 to 500 K. A model of antiferromagnetic (AFM) defects caused by controlled Rh substitution of the Pt site, reducing the TC, is proposed to interpret this phenomenon and the validity is further examined by ab initio density functional calculations.« less

Passive thermo-optic feedback for robust athermal photonic systems

DOEpatents

Rakich, Peter T.; Watts, Michael R.; Nielson, Gregory N.

2015-06-23

Thermal control devices, photonic systems and methods of stabilizing a temperature of a photonic system are provided. A thermal control device thermally coupled to a substrate includes a waveguide for receiving light, an absorption element optically coupled to the waveguide for converting the received light to heat and an optical filter. The optical filter is optically coupled to the waveguide and thermally coupled to the absorption element. An operating point of the optical filter is tuned responsive to the heat from the absorption element. When the operating point is less than a predetermined temperature, the received light is passed to the absorption element via the optical filter. When the operating point is greater than or equal to the predetermined temperature, the received light is transmitted out of the thermal control device via the optical filter, without being passed to the absorption element.

Tunable optical analog to electromagnetically induced transparency in graphene-ring resonators system

PubMed Central

Wang, Yonghua; Xue, Chenyang; Zhang, Zengxing; Zheng, Hua; Zhang, Wendong; Yan, Shubin

2016-01-01

The analogue of electromagnetically induced transparency in optical ways has shown great potential in optical delay and quantum-information technology due to its flexible design and easy implementation. The chief drawback for these devices is the bad tunability. Here we demonstrate a tunable optical transparency system formed by graphene-silicon microrings which could control the transparent window by electro-optical means. The device consists of cascaded coupled ring resonators and a graphene/graphene capacitor which integrated on one of the rings. By tuning the Fermi level of the graphene sheets, we can modulate the round-trip ring loss so that the transparency window can be dynamically tuned. The results provide a new method for the manipulation and transmission of light in highly integrated optical circuits and quantum information storage devices. PMID:27941895

An automatic data system for vibration modal tuning and evaluation

NASA Technical Reports Server (NTRS)

Salyer, R. A.; Jung, E. J., Jr.; Huggins, S. L.; Stephens, B. L.

1975-01-01

A digitally based automatic modal tuning and analysis system developed to provide an operational capability beginning at 0.1 hertz is described. The elements of the system, which provides unique control features, maximum operator visibility, and rapid data reduction and documentation, are briefly described; and the operational flow is discussed to illustrate the full range of capabilities and the flexibility of application. The successful application of the system to a modal survey of the Skylab payload is described. Information about the Skylab test article, coincident-quadrature analysis of modal response data, orthogonality, and damping calculations is included in the appendixes. Recommendations for future application of the system are also made.

Quantitative measurements of nanoscale permittivity and conductivity using tuning-fork-based microwave impedance microscopy

NASA Astrophysics Data System (ADS)

Wu, Xiaoyu; Hao, Zhenqi; Wu, Di; Zheng, Lu; Jiang, Zhanzhi; Ganesan, Vishal; Wang, Yayu; Lai, Keji

2018-04-01

We report quantitative measurements of nanoscale permittivity and conductivity using tuning-fork (TF) based microwave impedance microscopy (MIM). The system is operated under the driving amplitude modulation mode, which ensures satisfactory feedback stability on samples with rough surfaces. The demodulated MIM signals on a series of bulk dielectrics are in good agreement with results simulated by finite-element analysis. Using the TF-MIM, we have visualized the evolution of nanoscale conductance on back-gated MoS2 field effect transistors, and the results are consistent with the transport data. Our work suggests that quantitative analysis of mesoscopic electrical properties can be achieved by near-field microwave imaging with small distance modulation.

Neuromechanical tuning of nonlinear postural control dynamics

NASA Astrophysics Data System (ADS)

Ting, Lena H.; van Antwerp, Keith W.; Scrivens, Jevin E.; McKay, J. Lucas; Welch, Torrence D. J.; Bingham, Jeffrey T.; DeWeerth, Stephen P.

2009-06-01

Postural control may be an ideal physiological motor task for elucidating general questions about the organization, diversity, flexibility, and variability of biological motor behaviors using nonlinear dynamical analysis techniques. Rather than presenting "problems" to the nervous system, the redundancy of biological systems and variability in their behaviors may actually be exploited to allow for the flexible achievement of multiple and concurrent task-level goals associated with movement. Such variability may reflect the constant "tuning" of neuromechanical elements and their interactions for movement control. The problem faced by researchers is that there is no one-to-one mapping between the task goal and the coordination of the underlying elements. We review recent and ongoing research in postural control with the goal of identifying common mechanisms underlying variability in postural control, coordination of multiple postural strategies, and transitions between them. We present a delayed-feedback model used to characterize the variability observed in muscle coordination patterns during postural responses to perturbation. We emphasize the significance of delays in physiological postural systems, requiring the modulation and coordination of both the instantaneous, "passive" response to perturbations as well as the delayed, "active" responses to perturbations. The challenge for future research lies in understanding the mechanisms and principles underlying neuromechanical tuning of and transitions between the diversity of postural behaviors. Here we describe some of our recent and ongoing studies aimed at understanding variability in postural control using physical robotic systems, human experiments, dimensional analysis, and computational models that could be enhanced from a nonlinear dynamics approach.

Polarization response of RHIC electron lens lattices

DOE PAGES

Ranjbar, V. H.; Méot, F.; Bai, M.; ...

2016-10-10

Depolarization response for a system of two orthogonal snakes at irrational tunes is studied in depth using lattice independent spin integration. Particularly, we consider the effect of overlapping spin resonances in this system, to understand the impact of phase, tune, relative location and threshold strengths of the spin resonances. Furthermore, these results are benchmarked and compared to two dimensional direct tracking results for the RHIC e-lens lattice and the standard lattice. We then consider the effect of longitudinal motion via chromatic scans using direct six dimensional lattice tracking.

Internally resonating lattices for bandgap generation and low-frequency vibration control

NASA Astrophysics Data System (ADS)

Baravelli, Emanuele; Ruzzene, Massimo

2013-12-01

The paper reports on a structural concept for high stiffness and high damping performance. A stiff external frame and an internal resonating lattice are combined in a beam-like assembly which is characterized by high frequency bandgaps and tuned vibration attenuation at low frequencies. The resonating lattice consists of an elastomeric material arranged according to a chiral topology which is designed to resonate at selected frequencies. The concept achieves high damping performance by combining the frequency-selective properties of internally resonating structures, with the energy dissipation characteristics of their constituent material. The flexible ligaments, the circular nodes and the non-central interactions of the chiral topology lead to dynamic deformation patterns which are beneficial to energy dissipation. Furthermore, tuning and grading of the elements of the lattice allows for tailoring of the resonating properties so that vibration attenuation is obtained over desired frequency ranges. Numerical and experimental results demonstrate the tuning flexibility of this concept and suggest its potential application for load-carrying structural members parts of vibration and shock prone systems.

Robust control for a biaxial servo with time delay system based on adaptive tuning technique.

PubMed

Chen, Tien-Chi; Yu, Chih-Hsien

2009-07-01

A robust control method for synchronizing a biaxial servo system motion is proposed in this paper. A new network based cross-coupled control and adaptive tuning techniques are used together to cancel out the skew error. The conventional fixed gain PID cross-coupled controller (CCC) is replaced with the adaptive cross-coupled controller (ACCC) in the proposed control scheme to maintain biaxial servo system synchronization motion. Adaptive-tuning PID (APID) position and velocity controllers provide the necessary control actions to maintain synchronization while following a variable command trajectory. A delay-time compensator (DTC) with an adaptive controller was augmented to set the time delay element, effectively moving it outside the closed loop, enhancing the stability of the robust controlled system. This scheme provides strong robustness with respect to uncertain dynamics and disturbances. The simulation and experimental results reveal that the proposed control structure adapts to a wide range of operating conditions and provides promising results under parameter variations and load changes.

Loss-induced super scattering and gain-induced absorption.

PubMed

Feng, Simin

2016-01-25

Giant transmission and reflection of a finite bandwidth are demonstrated at the same wavelength when the electromagnetic wave is incident on a subwavelength array of parity-time (PT) symmetric dimers embedded in a metallic film. Remarkably, this phenomenon vanishes if the metallic substrate is lossless while keeping other parameters unchanged. Moreover super scattering can also occur when increasing the loss of the dimers while keeping the gain unchanged. When the metafilm is adjusted to the vicinity of an exceptional point, tuning either the substrate dissipation or the loss of the dimers can lead to supper scattering in stark contrast to what would be expected in conventional systems. In addition, increasing the gain of the dimers can increase the absorption near the exceptional point. These phenomena indicate that the PT-synthetic plasmonic metafilm can function as a thinfilm PT-plasmonic laser or absorber depending on the tuning parameter. One implication is that super radiation is possible from a cavity by tuning cavity dissipation or lossy element inside the cavity.

Tunable Thin-Film Resonator Coupled to Two Qubits in a 3D Cavity

NASA Astrophysics Data System (ADS)

Ballard, Cody; Dutta, S. K.; Budoyo, R. P.; Voigt, K. D.; Lobb, C. J.; Wellstood, F. C.

We present preliminary results on using a tunable, thin-film lumped element LC resonator to couple two transmon qubits in a 3D microwave cavity. The cavity, which is used for readout, is made of aluminum and has a TE101 mode at 6.3 GHz. The LC resonator has a base frequency of about 5 GHz and the inductor contains two loops, each having a single Josephson junction. Applying magnetic flux to the loops modulates the overall inductance of the resonator allowing tuning over a 500 MHz range. Two Al/AlOx/Al transmon qubits are fabricated on the same sapphire substrate as the resonator, and are designed to have a charging energy of 200 MHz and a frequency that falls within the tuning range of the resonator. Observing the perturbations of the resonant frequencies of the qubits and the cavity as the LC resonator is tuned allows us to determine the coupling strengths between each qubit and the LC resonator and between the LC resonator and the cavity.

Active noise control using noise source having adaptive resonant frequency tuning through variable ring loading

NASA Technical Reports Server (NTRS)

Rajiyah, Harindra (Inventor); Pla, Frederic G. (Inventor); Hedeen, Robert A. (Inventor); Renshaw, Anthony A. (Inventor)

1995-01-01

A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of noise radiating structure is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating structure is tuned by a plurality of drivers arranged to contact the noise radiating structure. Excitation of the drivers causes expansion or contraction of the drivers, thereby varying the edge loading applied to the noise radiating structure. The drivers are actuated by a controller which receives input of a feedback signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the drivers, causing them to expand or contract. The noise radiating structure may be either the outer shroud of the engine or a ring mounted flush with an inner wall of the shroud or disposed in the interior of the shroud.

Tunable High Q Superconducting Microwave Resonator for Hybrid System with ^87Rb atoms

NASA Astrophysics Data System (ADS)

Kim, Zaeill; Voigt, K. D.; Lee, Jongmin; Hoffman, J. E.; Grover, J. A.; Ravets, S.; Zaretskey, V.; Palmer, B. S.; Hafezi, M.; Taylor, J. M.; Anderson, J. R.; Dragt, A. J.; Lobb, C. J.; Orozco, L. A.; Rolston, S. L.; Wellstood, F. C.

2012-02-01

We have developed a frequency tuning system for a ``lumped-element'' thin-film superconducting Al microwave resonator [1] on sapphire intended for coupling to hyperfine ground states of cold trapped ^87Rb atoms, which are separated by about fRb=6.83 GHz. At T=12 mK and on resonance at 6.81 GHz, the loaded quality factor was 120,000. By moving a carefully machined Al pin towards the inductor of the resonator using a piezo stage, we were able to tune the resonance frequency over a range of 35 MHz and within a few kHz of fRb. While measuring the power dependent response of the resonator at each tuned frequency, we observed anomalous decreases in the quality factor at several frequencies. These drops were more pronounced at lower power. We discuss our results, which suggest these resonances are attributable to discrete two-level systems.[4pt] [1] Z. Kim et al., AIP ADVANCES 1, 042107 (2011).

Dynamical tuning between nearly perfect reflection, absorption, and transmission of light via graphene/dielectric structures

PubMed Central

Linder, Jacob; Halterman, Klaus

2016-01-01

Exerting well-defined control over the reflection (R), absorption (A), and transmission (T) of electromagnetic waves is a key objective in quantum optics. To this end, one often utilizes hybrid structures comprised of elements with different optical properties in order to achieve features such as high R or high A for incident light. A desirable goal would be the possibility to tune between all three regimes of nearly perfect reflection, absorption, and transmission within the same device, thus swapping between the cases R → 1, A → 1, and T → 1 dynamically. We here show that a dielectric interfaced with a graphene layer on each side allows for precisely this: by tuning only the Fermi level of graphene, all three regimes can be reached in the THz regime and below. Moreover, we show that the inclusion of cylindrical defects in the system offers a different type of control of the scattering of electromagnetic waves by means of the graphene layers. PMID:27917886

Creating a Successful Training Program for Frontline Staff: The University of Minnesota's Integrated Student Services Model

ERIC Educational Resources Information Center

Peterson, Heather L.; Otto, Carrie L.

2011-01-01

Successfully preparing frontline counseling staff in an integrated student services model is a challenge--one that management staff in One Stop Student Services at the University of Minnesota, Twin Cities (UMTC) have been fine-tuning for almost ten years. The effort has required collaboration across units in a series of trial and error attempts…

Recurrent network dynamics reconciles visual motion segmentation and integration.

PubMed

Medathati, N V Kartheek; Rankin, James; Meso, Andrew I; Kornprobst, Pierre; Masson, Guillaume S

2017-09-12

In sensory systems, a range of computational rules are presumed to be implemented by neuronal subpopulations with different tuning functions. For instance, in primate cortical area MT, different classes of direction-selective cells have been identified and related either to motion integration, segmentation or transparency. Still, how such different tuning properties are constructed is unclear. The dominant theoretical viewpoint based on a linear-nonlinear feed-forward cascade does not account for their complex temporal dynamics and their versatility when facing different input statistics. Here, we demonstrate that a recurrent network model of visual motion processing can reconcile these different properties. Using a ring network, we show how excitatory and inhibitory interactions can implement different computational rules such as vector averaging, winner-take-all or superposition. The model also captures ordered temporal transitions between these behaviors. In particular, depending on the inhibition regime the network can switch from motion integration to segmentation, thus being able to compute either a single pattern motion or to superpose multiple inputs as in motion transparency. We thus demonstrate that recurrent architectures can adaptively give rise to different cortical computational regimes depending upon the input statistics, from sensory flow integration to segmentation.

Biotemplated Morpho Butterfly Wings for Tunable Structurally Colored Photocatalysts.

PubMed

Rodríguez, Robin E; Agarwal, Sneha P; An, Shun; Kazyak, Eric; Das, Debashree; Shang, Wen; Skye, Rachael; Deng, Tao; Dasgupta, Neil P

2018-02-07

Morpho sulkowskyi butterfly wings contain naturally occurring hierarchical nanostructures that produce structural coloration. The high aspect ratio and surface area of these wings make them attractive nanostructured templates for applications in solar energy and photocatalysis. However, biomimetic approaches to replicate their complex structural features and integrate functional materials into their three-dimensional framework are highly limited in precision and scalability. Herein, a biotemplating approach is presented that precisely replicates Morpho nanostructures by depositing nanocrystalline ZnO coatings onto wings via low-temperature atomic layer deposition (ALD). This study demonstrates the ability to precisely tune the natural structural coloration while also integrating multifunctionality by imparting photocatalytic activity onto fully intact Morpho wings. Optical spectroscopy and finite-difference time-domain numerical modeling demonstrate that ALD ZnO coatings can rationally tune the structural coloration across the visible spectrum. These structurally colored photocatalysts exhibit an optimal coating thickness to maximize photocatalytic activity, which is attributed to trade-offs between light absorption and catalytic quantum yield with increasing coating thickness. These multifunctional photocatalysts present a new approach to integrating solar energy harvesting into visually attractive surfaces that can be integrated into building facades or other macroscopic structures to impart aesthetic appeal.

Optimizing integrated luminosity of future hadron colliders

NASA Astrophysics Data System (ADS)

Benedikt, Michael; Schulte, Daniel; Zimmermann, Frank

2015-10-01

The integrated luminosity, a key figure of merit for any particle-physics collider, is closely linked to the peak luminosity and to the beam lifetime. The instantaneous peak luminosity of a collider is constrained by a number of boundary conditions, such as the available beam current, the maximum beam-beam tune shift with acceptable beam stability and reasonable luminosity lifetime (i.e., the empirical "beam-beam limit"), or the event pileup in the physics detectors. The beam lifetime at high-luminosity hadron colliders is largely determined by particle burn off in the collisions. In future highest-energy circular colliders synchrotron radiation provides a natural damping mechanism, which can be exploited for maximizing the integrated luminosity. In this article, we derive analytical expressions describing the optimized integrated luminosity, the corresponding optimum store length, and the time evolution of relevant beam parameters, without or with radiation damping, while respecting a fixed maximum value for the total beam-beam tune shift or for the event pileup in the detector. Our results are illustrated by examples for the proton-proton luminosity of the existing Large Hadron Collider (LHC) at its design parameters, of the High-Luminosity Large Hadron Collider (HL-LHC), and of the Future Circular Collider (FCC-hh).

Microfabricated electrospray emitter arrays with integrated extractor and accelerator electrodes for the propulsion of small spacecraft

NASA Astrophysics Data System (ADS)

Dandavino, S.; Ataman, C.; Ryan, C. N.; Chakraborty, S.; Courtney, D.; Stark, J. P. W.; Shea, H.

2014-07-01

Microfabricated electrospray thrusters could revolutionize the spacecraft industry by providing efficient propulsion capabilities to micro and nano satellites (1-100 kg). We present the modeling, design, fabrication and characterization of a new generation of devices, for the first time integrating in the fabrication process individual accelerator electrodes capable of focusing and accelerating the emitted sprays. Integrating these electrodes is a key milestone in the development of this technology; in addition to increasing the critical performance metrics of thrust, specific impulse and propulsive efficiency, the accelerators enable a number of new system features such as power tuning and thrust vectoring and balancing. Through microfabrication, we produced high density arrays (213 emitters cm-2) of capillary emitters, assembling them at wafer-level with an extractor/accelerator electrode pair separated by micro-sandblasted glass. Through IV measurements, we could confirm that acceleration could be decoupled from the extraction of the spray—an important element towards the flexibility of this technology. We present the largest reported internally fed microfabricated arrays operation, with 127 emitters spraying in parallel, for a total beam of 10-30 µA composed by 95% of ions. Effective beam focusing was also demonstrated, with plume half-angles being reduced from approximately 30° to 15° with 2000 V acceleration. Based on these results, we predict, with 3000 V acceleration, thrust per emitter of 38.4 nN, specific impulse of 1103 s and a propulsive efficiency of 22% with <1 mW/emitter power consumption.

Optical fiber-fault surveillance for passive optical networks in S-band operation window

NASA Astrophysics Data System (ADS)

Yeh, Chien-Hung; Chi, Sien

2005-07-01

An S-band (1470 to 1520 nm) fiber laser scheme, which uses multiple fiber Bragg grating (FBG) elements as feedback elements on each passive branch, is proposed and described for in-service fault identification in passive optical networks (PONs). By tuning a wavelength selective filter located within the laser cavity over a gain bandwidth, the fiber-fault of each branch can be monitored without affecting the in-service channels. In our experiment, an S-band four-branch monitoring tree-structured PON system is demonstrated and investigated experimentally.

Rotation flexure with temperature controlled modal frequency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salas, Theodore E.; Barney, Patrick S.; Ison, Aaron M.

A flexure bearing includes an inner race, an outer race, and a plurality of substantially planar radially extending blades coupled between the inner and outer race. The blades have a thickness that is thinner than a thickness of the inner and outer races. The inner race, outer race, and blades have substantially the same height. At least one heating element is coupled to the inner race and/or the outer race. The heating element is configured to apply heat to the race that it is coupled to in order to tune the flexure bearing.

The marriage of metallacycle transfer chemistry with Suzuki-Miyaura cross-coupling to give main group element-containing conjugated polymers.

PubMed

He, Gang; Kang, Le; Torres Delgado, William; Shynkaruk, Olena; Ferguson, Michael J; McDonald, Robert; Rivard, Eric

2013-04-10

A versatile and general synthetic route for the synthesis of conjugated main group element-based polymers, previously inaccessible by conventional means, is reported. These polymers contain five-membered chalcogenophene rings based on S, Se, and Te, and we demonstrate that optoelectronic properties can be readily tuned via controlled atom substitution chemistry. In addition, regioregular hybrid thiophene-selenophene-tellurophene and selenophene-fluorene copolymers were synthesized to provide a further illustration of the scope of the presented metallacycle transfer/cross-coupling polymerization method.

A least-squares finite element method for incompressible Navier-Stokes problems

NASA Technical Reports Server (NTRS)

Jiang, Bo-Nan

1992-01-01

A least-squares finite element method, based on the velocity-pressure-vorticity formulation, is developed for solving steady incompressible Navier-Stokes problems. This method leads to a minimization problem rather than to a saddle-point problem by the classic mixed method and can thus accommodate equal-order interpolations. This method has no parameter to tune. The associated algebraic system is symmetric, and positive definite. Numerical results for the cavity flow at Reynolds number up to 10,000 and the backward-facing step flow at Reynolds number up to 900 are presented.

Optical fiber-fault surveillance for passive optical networks in S-band operation window.

PubMed

Yeh, Chien-Hung; Chi, Sien

2005-07-11

An S-band (1470 to 1520 nm) fiber laser scheme, which uses multiple fiber Bragg grating (FBG) elements as feedback elements on each passive branch, is proposed and described for in-service fault identification in passive optical networks (PONs). By tuning a wavelength selective filter located within the laser cavity over a gain bandwidth, the fiber-fault of each branch can be monitored without affecting the in-service channels. In our experiment, an S-band four-branch monitoring tree-structured PON system is demonstrated and investigated experimentally.

Imaging Implicit Morphological Processing: Evidence from Hebrew

ERIC Educational Resources Information Center

Bick, Atira S.; Frost, Ram; Goelman, Gadi

2010-01-01

Is morphology a discrete and independent element of lexical structure or does it simply reflect a fine-tuning of the system to the statistical correlation that exists among orthographic and semantic properties of words? Hebrew provides a unique opportunity to examine morphological processing in the brain because of its rich morphological system.…

Red/near-infrared luminescence tuning of group-14 element complexes of dipyrrins based on a central atom.

PubMed

Yamamura, Masaki; Albrecht, Marcel; Albrecht, Markus; Nishimura, Yoshinobu; Arai, Tatsuo; Nabeshima, Tatsuya

2014-02-03

A dipyrrin complex has been one of the most utilized fluorescent dyes, and a variety of dipyrrin complexes show intriguing functions based on the various coordination structures of the central element. We now report the synthesis, structure, and photophysical properties of germanium and stannane complexes of the N2O2-type tetradentate dipyrrin, L·Ge and L·Sn, which are heavier analogues of the previously reported dipyrrin silicon complex, L·Si. The central group-14 atoms of the monomeric complexes have geometries close to trigonal bipyramidal (TBP), in which the contribution of the square-pyramidal (SP) character becomes higher as the central atom is heavier. Interestingly, L·Sn formed a dimeric structure in the crystal. All complexes L·Si, L·Ge, and L·Sn showed a fluorescence in the red/NIR region. Fluorescence quantum yields of L·Ge and L·Sn are higher than that of L·Si. These results indicated that the central atom on the dipyrrin complexes contributes not only to the geometry difference but also to tuning the fluorescence properties.

Finite-element-based matching of pre- and intraoperative data for image-guided endovascular aneurysm repair

PubMed Central

Dumenil, Aurélien; Kaladji, Adrien; Castro, Miguel; Esneault, Simon; Lucas, Antoine; Rochette, Michel; Goksu, Cemil; Haigron, Pascal

2013-01-01

Endovascular repair of abdominal aortic aneurysms is a well-established technique throughout the medical and surgical communities. Although increasingly indicated, this technique does have some limitations. Because intervention is commonly performed under fluoroscopic control, two-dimensional (2D) visualization of the aneurysm requires the injection of a contrast agent. The projective nature of this imaging modality inevitably leads to topographic errors, and does not give information on arterial wall quality at the time of deployment. A specially-adapted intraoperative navigation interface could increase deployment accuracy and reveal such information, which preoperative three-dimensional (3D) imaging might otherwise provide. One difficulty is the precise matching of preoperative data (images and models) and intraoperative observations affected by anatomical deformations due to tool-tissue interactions. Our proposed solution involves a finite element-based preoperative simulation of tool/tissue interactions, its adaptive tuning regarding patient specific data, and the matching with intra-operative data. The biomechanical model was first tuned on a group of 10 patients and assessed on a second group of 8 patients. PMID:23269745

Interfaces in Heterogeneous Catalysts: Advancing Mechanistic Understanding through Atomic-Scale Measurements.

PubMed

Gao, Wenpei; Hood, Zachary D; Chi, Miaofang

2017-04-18

Developing novel catalysts with high efficiency and selectivity is critical for enabling future clean energy conversion technologies. Interfaces in catalyst systems have long been considered the most critical factor in controlling catalytic reaction mechanisms. Interfaces include not only the catalyst surface but also interfaces within catalyst particles and those formed by constructing heterogeneous catalysts. The atomic and electronic structures of catalytic surfaces govern the kinetics of binding and release of reactant molecules from surface atoms. Interfaces within catalysts are introduced to enhance the intrinsic activity and stability of the catalyst by tuning the surface atomic and chemical structures. Examples include interfaces between the core and shell, twin or domain boundaries, or phase boundaries within single catalyst particles. In supported catalyst nanoparticles (NPs), the interface between the metallic NP and support serves as a critical tuning factor for enhancing catalytic activity. Surface electronic structure can be indirectly tuned and catalytically active sites can be increased through the use of supporting oxides. Tuning interfaces in catalyst systems has been identified as an important strategy in the design of novel catalysts. However, the governing principle of how interfaces contribute to catalyst behavior, especially in terms of interactions with intermediates and their stability during electrochemical operation, are largely unknown. This is mainly due to the evolving nature of such interfaces. Small changes in the structural and chemical configuration of these interfaces may result in altering the catalytic performance. These interfacial arrangements evolve continuously during synthesis, processing, use, and even static operation. A technique that can probe the local atomic and electronic interfacial structures with high precision while monitoring the dynamic interfacial behavior in situ is essential for elucidating the role of interfaces and providing deeper insight for fine-tuning and optimizing catalyst properties. Scanning transmission electron microscopy (STEM) has long been a primary characterization technique used for studying nanomaterials because of its exceptional imaging resolution and simultaneous chemical analysis. Over the past decade, advances in STEM, that is, the commercialization of both aberration correctors and monochromators, have significantly improved the spatial and energy resolution. Imaging atomic structures with subangstrom resolution and identifying chemical species with single-atom sensitivity are now routine for STEM. These advancements have greatly benefitted catalytic research. For example, the roles of lattice strain and surface elemental distribution and their effect on catalytic stability and reactivity have been well documented in bimetallic catalysts. In addition, three-dimensional atomic structures revealed by STEM tomography have been integrated in theoretical modeling for predictive catalyst NP design. Recent developments in stable electronic and mechanical devices have opened opportunities to monitor the evolution of catalysts in operando under synthesis and reaction conditions; high-speed direct electron detectors have achieved sub-millisecond time resolutions and allow for rapid structural and chemical changes to be captured. Investigations of catalysts using these latest microscopy techniques have provided new insights into atomic-level catalytic mechanisms. Further integration of new microscopy methods is expected to provide multidimensional descriptions of interfaces under relevant synthesis and reaction conditions. In this Account, we discuss recent insights on understanding catalyst activity, selectivity, and stability using advanced STEM techniques, with an emphasis on how critical interfaces dictate the performance of precious metal-based heterogeneous catalysts. The role of extended interfacial structures, including those between core and shell, between separate phases and twinned grains, between the catalyst surface and gas, and between metal and support are discussed. We also provide an outlook on how emerging electron microscopy techniques, such as vibrational spectroscopy and electron ptychography, will impact future catalysis research.

Integrable RCS as a Proposed Replacement for Fermilab Booster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eldred, Jeffrey; Valishev, Alexander

2017-03-07

Integrable optics is an innovation in particle accelerator design that potentially enables a greater betatron tune spread and damps collective instabilities. An integrable rapid-cycling synchrotron (RCS) would be an effective replacement for the Fermilab Booster, as part of a plan to reach multi-MW beam power at 120 GeV for the Fermilab high-energy neutrino program. We provide an example integrable lattice with features of a modern RCS - dispersion-free drifts, low momentum compaction factor, superperiodicity, chromaticity correction, bounded beta functions, and separate-function magnets.

Wide-band polarization controller for Si photonic integrated circuits.

PubMed

Velha, P; Sorianello, V; Preite, M V; De Angelis, G; Cassese, T; Bianchi, A; Testa, F; Romagnoli, M

2016-12-15

A circuit for the management of any arbitrary polarization state of light is demonstrated on an integrated silicon (Si) photonics platform. This circuit allows us to adapt any polarization into the standard fundamental TE mode of a Si waveguide and, conversely, to control the polarization and set it to any arbitrary polarization state. In addition, the integrated thermal tuning allows kilohertz speed which can be used to perform a polarization scrambler. The circuit was used in a WDM link and successfully used to adapt four channels into a standard Si photonic integrated circuit.

Design and performance of coded aperture optical elements for the CESR-TA x-ray beam size monitor

NASA Astrophysics Data System (ADS)

Alexander, J. P.; Chatterjee, A.; Conolly, C.; Edwards, E.; Ehrlichman, M. P.; Flanagan, J. W.; Fontes, E.; Heltsley, B. K.; Lyndaker, A.; Peterson, D. P.; Rider, N. T.; Rubin, D. L.; Seeley, R.; Shanks, J.

2014-12-01

We describe the design and performance of optical elements for an x-ray beam size monitor (xBSM), a device measuring e+ and e- beam sizes in the CESR-TA storage ring. The device can measure vertical beam sizes of 10 - 100 μm on a turn-by-turn, bunch-by-bunch basis at e± beam energies of 2 - 5 GeV. x-rays produced by a hard-bend magnet pass through a single- or multiple-slit (coded aperture) optical element onto a detector. The coded aperture slit pattern and thickness of masking material forming that pattern can both be tuned for optimal resolving power. We describe several such optical elements and show how well predictions of simple models track measured performances.

Large format imaging arrays for the Atacama Cosmology Telescope

NASA Technical Reports Server (NTRS)

Chervenak, J. A.; Wollack, E. J.; Marraige, T.; Staggs, S.; Niemack, M.; Doriese, B.

2006-01-01

We describe progress in the fabrication, characterization, and production of detector arrays for the Atacama Cosmology Telescope (ACT). The completed ACT instrument is specified to image simultaneously at 145, 225, and 265 GHz using three 32x32 filled arrays of superconducting transition edge sensors (TES) read out with time-division-multiplexed SQUID amplifiers. We present details of the pixel design and testing including the optimization of the electrical parameters for multiplexed readout. Using geometric noise suppression and careful tuning of operation temperature and device bias resistance, the excess noise in the TES devices is balanced with detector speed for interfacing with the ACT optics. The design also accounts for practical tolerances such as transition temperature gradients and scatter that occur in the production of multiple wafers to populate fully the kilopixel cameras. We have developed an implanted absorber layer compatible with our silicon-on-insulator process that allows for tunable optical resistance with requisite on-wafer uniformity and wafer-to-wafer reproducibility. Arrays of 32 elements have been tested in the laboratory environment including electrical, optical, and multiplexed performance. Given this pixel design, optical tests and modeling are used to predict the performance of the filled array under anticipated viewing conditions. Integration of the filled array of pixels with a tuned backshort and dielectric plate in front of the array maximize absorption and the focal plane and suppress reflections. A mechanical design for the build of the full structure is completed and we report on progress toward the construction of a prototype array for first light on the ACT.

Astrochronology of a Late Oligocene to Early Miocene Magnetostratigraphy from the Northwest Atlantic

NASA Astrophysics Data System (ADS)

van Peer, T. E.; Xuan, C.; Liebrand, D.; Lippert, P. C.; Wilson, P. A.

2016-12-01

The Oligocene-Miocene Boundary is defined by the geomagnetic polarity reversal C6Cn.2n/C6Cn.2r with an astronomically tuned age of 23 Ma. For late Oligocene to early Miocene reversals, only a few records (mainly from the equatorial Pacific and South Atlantic) integrate magneto- and cyclo-stratigraphy with astronomical tuning. Reversal ages acquired from these records show differences up to 100 kyr. We report new astronomically tuned ages for reversals between 21-26.5 Ma, based on integrated palaeomagnetic and X-Ray Fluorescence (XRF) data from rapidly accumulated drift sediments (mean sedimentation rate of 2.5 cm/kyr) at Integrated Ocean Drilling Program (IODP) Site U1406 (northwest Atlantic). The natural remanence preserved in the sediments is relatively weak (especially at high demagnetisation steps) and prone to influence from measurement noise. We introduce an optimisation protocol to improve the estimation of component directions used to define the reversals. For each 1-cm interval measurement, the protocol searches for the combination of a fixed number of steps of demagnetisation data that minimises the maximum angular deviation, statistically excluding the noisy measurement steps. For the tuning, we use the logarithm of the calcium over potassium ratio ln(Ca/K) from XRF core scanning data, a proxy of carbonate content in the sediment. Spectral and wavelet analyses of the 140-m long ln(Ca/K) record highlight dominant obliquity (including the 178 and 1200 kyr modulation) and additional eccentricity forcing. Supported by preliminary stable isotope analysis on benthic foraminifera, we tuned ln(Ca/K) minima to obliquity minima and eccentricity maxima. The resulting age model yield new independent ages for all reversals between C6Ar/C6AAn to C8r/C9n. Our results are generally consistent (within an obliquity cycle) with the Ocean Drilling Program (ODP) Site 1090 age model [Billups et al., 2004], but deviate up to 80 kyr relative to ODP Site 1218 [Pälike et al., 2006] and ATNTS2004 [Lourens et al., 2004] age models. The concurrent high-fidelity reversal ages from ODP Site 1090 and IODP Site U1406 reconcile discrepancies in the early Miocene GPTS, and provide improved temporal constraints, which are critical to the study of palaeomagnetic and environmental changes of this time interval.

On the effect of response transformations in sequential parameter optimization.

PubMed

Wagner, Tobias; Wessing, Simon

2012-01-01

Parameter tuning of evolutionary algorithms (EAs) is attracting more and more interest. In particular, the sequential parameter optimization (SPO) framework for the model-assisted tuning of stochastic optimizers has resulted in established parameter tuning algorithms. In this paper, we enhance the SPO framework by introducing transformation steps before the response aggregation and before the actual modeling. Based on design-of-experiments techniques, we empirically analyze the effect of integrating different transformations. We show that in particular, a rank transformation of the responses provides significant improvements. A deeper analysis of the resulting models and additional experiments with adaptive procedures indicates that the rank and the Box-Cox transformation are able to improve the properties of the resultant distributions with respect to symmetry and normality of the residuals. Moreover, model-based effect plots document a higher discriminatory power obtained by the rank transformation.

Improving the lateral resolution of quartz tuning fork-based sensors in liquid by integrating commercial AFM tips into the fiber end.

PubMed

Gonzalez, Laura; Martínez-Martín, David; Otero, Jorge; de Pablo, Pedro José; Puig-Vidal, Manel; Gómez-Herrero, Julio

2015-01-14

The use of quartz tuning fork sensors as probes for scanning probe microscopy is growing in popularity. Working in shear mode, some methods achieve a lateral resolution comparable with that obtained with standard cantilevered probes, but only in experiments conducted in air or vacuum. Here, we report a method to produce and use commercial AFM tips in electrically driven quartz tuning fork sensors operating in shear mode in a liquid environment. The process is based on attaching a standard AFM tip to the end of a fiber probe which has previously been sharpened. Only the end of the probe is immersed in the buffer solution during imaging. The lateral resolution achieved is about 6 times higher than that of the etched microfiber on its own.

Wavelength-selective ultraviolet (Mg,Zn)O photodiodes: Tuning of parallel composition gradients with oxygen pressure

NASA Astrophysics Data System (ADS)

Zhang, Zhipeng; von Wenckstern, Holger; Lenzner, Jörg; Grundmann, Marius

2016-06-01

We report on ultraviolet photodiodes with integrated optical filter based on the wurtzite (Mg,Zn)O thin films. Tuning of the bandgap of filter and active layers was realized by employing a continuous composition spread approach relying on the ablation of a single segmented target in pulsed-laser deposition. Filter and active layers of the device were deposited on opposite sides of a sapphire substrate with nearly parallel compositional gradients. Ensure that for each sample position the bandgap of the filter layer blocking the high energy radiation is higher than that of the active layer. Different oxygen pressures during the two depositions runs. The absorption edge is tuned over 360 meV and the spectral bandwidth of photodiodes is typically 100 meV and as low as 50 meV.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bachman, Daniel; Chen, Zhijiang; Wang, Christopher

Phase errors caused by fabrication variations in silicon photonic integrated circuits are an important problem, which negatively impacts device yield and performance. This study reports our recent progress in the development of a method for permanent, postfabrication phase error correction of silicon photonic circuits based on femtosecond laser irradiation. Using beam shaping technique, we achieve a 14-fold enhancement in the phase tuning resolution of the method with a Gaussian-shaped beam compared to a top-hat beam. The large improvement in the tuning resolution makes the femtosecond laser method potentially useful for very fine phase trimming of silicon photonic circuits. Finally, wemore » also show that femtosecond laser pulses can directly modify silicon photonic devices through a SiO 2 cladding layer, making it the only permanent post-fabrication method that can tune silicon photonic circuits protected by an oxide cladding.« less

The Fate of Visible Features of Invisible Elements

PubMed Central

Herzog, Michael H.; Otto, Thomas U.; Ögmen, Haluk

2012-01-01

To investigate the integration of features, we have developed a paradigm in which an element is rendered invisible by visual masking. Still, the features of the element are visible as part of other display elements presented at different locations and times (sequential metacontrast). In this sense, we can “transport” features non-retinotopically across space and time. The features of the invisible element integrate with features of other elements if and only if the elements belong to the same spatio-temporal group. The mechanisms of this kind of feature integration seem to be quite different from classical mechanisms proposed for feature binding. We propose that feature processing, binding, and integration occur concurrently during processes that group elements into wholes. PMID:22557985

Telecom meets terahertz

NASA Astrophysics Data System (ADS)

Nikitin, Alexey Y.

2018-01-01

Excitation and gate tuning of terahertz plasmons in dual-layer graphene integrated into on-chip telecom photonic waveguides using infrared lasers has now been demonstrated. This may open the door to atomically thick optoelectronic devices for security, tomography or data processing.

Sliding mode control of dissolved oxygen in an integrated nitrogen removal process in a sequencing batch reactor (SBR).

PubMed

Muñoz, C; Young, H; Antileo, C; Bornhardt, C

2009-01-01

This paper presents a sliding mode controller (SMC) for dissolved oxygen (DO) in an integrated nitrogen removal process carried out in a suspended biomass sequencing batch reactor (SBR). The SMC performance was compared against an auto-tuning PI controller with parameters adjusted at the beginning of the batch cycle. A method for cancelling the slow DO sensor dynamics was implemented by using a first order model of the sensor. Tests in a lab-scale reactor showed that the SMC offers a better disturbance rejection capability than the auto-tuning PI controller, furthermore providing reasonable performance in a wide range of operation. Thus, SMC becomes an effective robust nonlinear tool to the DO control in this process, being also simple from a computational point of view, allowing its implementation in devices such as industrial programmable logic controllers (PLCs).

A Simple Attitude Control of Quadrotor Helicopter Based on Ziegler-Nichols Rules for Tuning PD Parameters

PubMed Central

He, ZeFang

2014-01-01

An attitude control strategy based on Ziegler-Nichols rules for tuning PD (proportional-derivative) parameters of quadrotor helicopters is presented to solve the problem that quadrotor tends to be instable. This problem is caused by the narrow definition domain of attitude angles of quadrotor helicopters. The proposed controller is nonlinear and consists of a linear part and a nonlinear part. The linear part is a PD controller with PD parameters tuned by Ziegler-Nichols rules and acts on the quadrotor decoupled linear system after feedback linearization; the nonlinear part is a feedback linearization item which converts a nonlinear system into a linear system. It can be seen from the simulation results that the attitude controller proposed in this paper is highly robust, and its control effect is better than the other two nonlinear controllers. The nonlinear parts of the other two nonlinear controllers are the same as the attitude controller proposed in this paper. The linear part involves a PID (proportional-integral-derivative) controller with the PID controller parameters tuned by Ziegler-Nichols rules and a PD controller with the PD controller parameters tuned by GA (genetic algorithms). Moreover, this attitude controller is simple and easy to implement. PMID:25614879

Miniature electrically tunable rotary dual-focus lenses

NASA Astrophysics Data System (ADS)

Zou, Yongchao; Zhang, Wei; Lin, Tong; Chau, Fook Siong; Zhou, Guangya

2016-03-01

The emerging dual-focus lenses are drawing increasing attention recently due to their wide applications in both academia and industries, including laser cutting systems, microscopy systems, and interferometer-based surface profilers. In this paper, a miniature electrically tunable rotary dual-focus lens is developed. Such a lens consists of two optical elements, each having an optical flat surface and one freeform surface. The two freeform surfaces are initialized with the governing equation Ar2θ (A is the constant to be determined, r and θ denote the radii and angles in the polar coordinate system) and then optimized by ray tracing technique with additional Zernike polynomial terms for aberration correction. The freeform surfaces are achieved by a single-point diamond turning technique and then a PDMS-based replication process is utilized to materialize the final lens elements. To drive the two coaxial elements to rotate independently, two MEMS thermal rotary actuators are developed and fabricated by a standard MUMPs process. The experimental results show that the MEMS thermal actuator provides a maximum rotation angle of about 8.2 degrees with an input DC voltage of 6.5 V, leading to a wide tuning range for both the two focal lengths of the lens. Specifically, one focal length can be tuned from about 30 mm to 20 mm while the other one can be adjusted from about 30 mm to 60 mm.

Intelligent tuning method of PID parameters based on iterative learning control for atomic force microscopy.

PubMed

Liu, Hui; Li, Yingzi; Zhang, Yingxu; Chen, Yifu; Song, Zihang; Wang, Zhenyu; Zhang, Suoxin; Qian, Jianqiang

2018-01-01

Proportional-integral-derivative (PID) parameters play a vital role in the imaging process of an atomic force microscope (AFM). Traditional parameter tuning methods require a lot of manpower and it is difficult to set PID parameters in unattended working environments. In this manuscript, an intelligent tuning method of PID parameters based on iterative learning control is proposed to self-adjust PID parameters of the AFM according to the sample topography. This method gets enough information about the output signals of PID controller and tracking error, which will be used to calculate the proper PID parameters, by repeated line scanning until convergence before normal scanning to learn the topography. Subsequently, the appropriate PID parameters are obtained by fitting method and then applied to the normal scanning process. The feasibility of the method is demonstrated by the convergence analysis. Simulations and experimental results indicate that the proposed method can intelligently tune PID parameters of the AFM for imaging different topographies and thus achieve good tracking performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tuned Chamber Core Panel Acoustic Test Results

NASA Technical Reports Server (NTRS)

Schiller, Noah H.; Allen, Albert R.

2016-01-01

This report documents acoustic testing of tuned chamber core panels, which can be used to supplement the low-frequency performance of conventional acoustic treatment. The tuned chamber core concept incorporates low-frequency noise control directly within the primary structure and is applicable to sandwich constructions with a directional core, including corrugated-, truss-, and fluted-core designs. These types of sandwich structures have long, hollow channels (or chambers) in the core. By adding small holes through one of the facesheets, the hollow chambers can be utilized as an array of low-frequency acoustic resonators. These resonators can then be used to attenuate low-frequency noise (below 400 Hz) inside a vehicle compartment without increasing the weight or size of the structure. The results of this test program demonstrate that the tuned chamber core concept is effective when used in isolation or combined with acoustic foam treatments. Specifically, an array of acoustic resonators integrated within the core of the panels was shown to improve both the low-frequency absorption and transmission loss of the structure in targeted one-third octave bands.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zheng; Xu, Xiaochuan; Fan, Donglei

Here, subwavelength grating (SWG) waveguide is an intriguing alternative to conventional optical waveguides due to the extra degree of freedom it offers in tuning a few important waveguide properties, such as dispersion and refractive index. Devices based on SWG waveguides have demonstrated impressive performances compared to conventional waveguides. However, the high loss of SWG waveguide bends jeopardizes their applications in integrated photonic circuits. In this work, we propose a geometrical tuning art, which realizes a pre-distorted refractive index profile in SWG waveguide bends. The pre-distorted refractive index profile can effectively reduce the mode mismatch and radiation loss simultaneously, thus significantlymore » reduce the bend loss. This geometry tuning art has been numerically optimized and experimentally demonstrated in present study. Through such tuning, the average insertion loss of a 5 μm SWG waveguide bend is reduced drastically from 5.43 dB to 1.10 dB per 90° bend for quasi-TE polarization. In the future, the proposed scheme will be utilized to enhance performance of a wide range of SWG waveguide based photonics devices.« less

Bright infrared quantum-dot light-emitting diodes through inter-dot spacing control.

PubMed

Sun, Liangfeng; Choi, Joshua J; Stachnik, David; Bartnik, Adam C; Hyun, Byung-Ryool; Malliaras, George G; Hanrath, Tobias; Wise, Frank W

2012-05-06

Infrared light-emitting diodes are currently fabricated from direct-gap semiconductors using epitaxy, which makes them expensive and difficult to integrate with other materials. Light-emitting diodes based on colloidal semiconductor quantum dots, on the other hand, can be solution-processed at low cost, and can be directly integrated with silicon. However, so far, exciton dissociation and recombination have not been well controlled in these devices, and this has limited their performance. Here, by tuning the distance between adjacent PbS quantum dots, we fabricate thin-film quantum-dot light-emitting diodes that operate at infrared wavelengths with radiances (6.4 W sr(-1) m(-2)) eight times higher and external quantum efficiencies (2.0%) two times higher than the highest values previously reported. The distance between adjacent dots is tuned over a range of 1.3 nm by varying the lengths of the linker molecules from three to eight CH(2) groups, which allows us to achieve the optimum balance between charge injection and radiative exciton recombination. The electroluminescent powers of the best devices are comparable to those produced by commercial InGaAsP light-emitting diodes. By varying the size of the quantum dots, we can tune the emission wavelengths between 800 and 1,850 nm.

An Integrated Approach for Aircraft Engine Performance Estimation and Fault Diagnostics

NASA Technical Reports Server (NTRS)

imon, Donald L.; Armstrong, Jeffrey B.

2012-01-01

A Kalman filter-based approach for integrated on-line aircraft engine performance estimation and gas path fault diagnostics is presented. This technique is specifically designed for underdetermined estimation problems where there are more unknown system parameters representing deterioration and faults than available sensor measurements. A previously developed methodology is applied to optimally design a Kalman filter to estimate a vector of tuning parameters, appropriately sized to enable estimation. The estimated tuning parameters can then be transformed into a larger vector of health parameters representing system performance deterioration and fault effects. The results of this study show that basing fault isolation decisions solely on the estimated health parameter vector does not provide ideal results. Furthermore, expanding the number of the health parameters to address additional gas path faults causes a decrease in the estimation accuracy of those health parameters representative of turbomachinery performance deterioration. However, improved fault isolation performance is demonstrated through direct analysis of the estimated tuning parameters produced by the Kalman filter. This was found to provide equivalent or superior accuracy compared to the conventional fault isolation approach based on the analysis of sensed engine outputs, while simplifying online implementation requirements. Results from the application of these techniques to an aircraft engine simulation are presented and discussed.

Isotropic matrix elements of the collision integral for the Boltzmann equation

NASA Astrophysics Data System (ADS)

Ender, I. A.; Bakaleinikov, L. A.; Flegontova, E. Yu.; Gerasimenko, A. B.

2017-09-01

We have proposed an algorithm for constructing matrix elements of the collision integral for the nonlinear Boltzmann equation isotropic in velocities. These matrix elements have been used to start the recurrent procedure for calculating matrix elements of the velocity-nonisotropic collision integral described in our previous publication. In addition, isotropic matrix elements are of independent interest for calculating isotropic relaxation in a number of physical kinetics problems. It has been shown that the coefficients of expansion of isotropic matrix elements in Ω integrals are connected by the recurrent relations that make it possible to construct the procedure of their sequential determination.

Shared reality in intergroup communication: Increasing the epistemic authority of an out-group audience.

PubMed

Echterhoff, Gerald; Kopietz, René; Higgins, E Tory

2017-06-01

Communicators typically tune messages to their audience's attitude. Such audience tuning biases communicators' memory for the topic toward the audience's attitude to the extent that they create a shared reality with the audience. To investigate shared reality in intergroup communication, we first established that a reduced memory bias after tuning messages to an out-group (vs. in-group) audience is a subtle index of communicators' denial of shared reality to that out-group audience (Experiments 1a and 1b). We then examined whether the audience-tuning memory bias might emerge when the out-group audience's epistemic authority is enhanced, either by increasing epistemic expertise concerning the communication topic or by creating epistemic consensus among members of a multiperson out-group audience. In Experiment 2, when Germans communicated to a Turkish audience with an attitude about a Turkish (vs. German) target, the audience-tuning memory bias appeared. In Experiment 3, when the audience of German communicators consisted of 3 Turks who all held the same attitude toward the target, the memory bias again appeared. The association between message valence and memory valence was consistently higher when the audience's epistemic authority was high (vs. low). An integrative analysis across all studies also suggested that the memory bias increases with increasing strength of epistemic inputs (epistemic expertise, epistemic consensus, and audience-tuned message production). The findings suggest novel ways of overcoming intergroup biases in intergroup relations. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Quantitative measurements of nanoscale permittivity and conductivity using tuning-fork-based microwave impedance microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Xiaoyu; Hao, Zhenqi; Wu, Di

Here, we report quantitative measurements of nanoscale permittivity and conductivity using tuning-fork (TF) based microwave impedance microscopy (MIM). The system is operated under the driving amplitude modulation mode, which ensures satisfactory feedback stability on samples with rough surfaces. The demodulated MIM signals on a series of bulk dielectrics are in good agreement with results simulated by finite-element analysis. Using the TF-MIM, we have visualized the evolution of nanoscale conductance on back-gated MoS 2 field effect transistors, and the results are consistent with the transport data. Our work suggests that quantitative analysis of mesoscopic electrical properties can be achieved by near-fieldmore » microwave imaging with small distance modulation.« less

Quantitative measurements of nanoscale permittivity and conductivity using tuning-fork-based microwave impedance microscopy

DOE PAGES

Wu, Xiaoyu; Hao, Zhenqi; Wu, Di; ...

2018-04-01

Here, we report quantitative measurements of nanoscale permittivity and conductivity using tuning-fork (TF) based microwave impedance microscopy (MIM). The system is operated under the driving amplitude modulation mode, which ensures satisfactory feedback stability on samples with rough surfaces. The demodulated MIM signals on a series of bulk dielectrics are in good agreement with results simulated by finite-element analysis. Using the TF-MIM, we have visualized the evolution of nanoscale conductance on back-gated MoS 2 field effect transistors, and the results are consistent with the transport data. Our work suggests that quantitative analysis of mesoscopic electrical properties can be achieved by near-fieldmore » microwave imaging with small distance modulation.« less

A study of methods to predict and measure the transmission of sound through the walls of light aircraft. Integration of certain singular boundary element integrals for applications in linear acoustics

NASA Technical Reports Server (NTRS)

Zimmerle, D.; Bernhard, R. J.

1985-01-01

An alternative method for performing singular boundary element integrals for applications in linear acoustics is discussed. The method separates the integral of the characteristic solution into a singular and nonsingular part. The singular portion is integrated with a combination of analytic and numerical techniques while the nonsingular portion is integrated with standard Gaussian quadrature. The method may be generalized to many types of subparametric elements. The integrals over elements containing the root node are considered, and the characteristic solution for linear acoustic problems are examined. The method may be generalized to most characteristic solutions.

Tuning in to Youths' Media Culture.

ERIC Educational Resources Information Center

Trampiets, Frances

1998-01-01

Presents a four-stage model for dioceses wishing to integrate media literacy into elementary and secondary religious studies and parish youth programs. Describes the Vatican's 1992 Aetatis Novae: Pastoral Instruction on Social Communications, and its effect on Catholic curricula. (VWC)

Conserved structures formed by heterogeneous RNA sequences drive silencing of an inflammation responsive post-transcriptional operon

PubMed Central

Basu, Abhijit; Jain, Niyati; Tolbert, Blanton S.; Komar, Anton A.

2017-01-01

Abstract RNA–protein interactions with physiological outcomes usually rely on conserved sequences within the RNA element. By contrast, activity of the diverse gamma-interferon-activated inhibitor of translation (GAIT)-elements relies on the conserved RNA folding motifs rather than the conserved sequence motifs. These elements drive the translational silencing of a group of chemokine (CC/CXC) and chemokine receptor (CCR) mRNAs, thereby helping to resolve physiological inflammation. Despite sequence dissimilarity, these RNA elements adopt common secondary structures (as revealed by 2D-1H NMR spectroscopy), providing a basis for their interaction with the RNA-binding GAIT complex. However, many of these elements (e.g. those derived from CCL22, CXCL13, CCR4 and ceruloplasmin (Cp) mRNAs) have substantially different affinities for GAIT complex binding. Toeprinting analysis shows that different positions within the overall conserved GAIT element structure contribute to differential affinities of the GAIT protein complex towards the elements. Thus, heterogeneity of GAIT elements may provide hierarchical fine-tuning of the resolution of inflammation. PMID:29069516

Integration Testing of Space Flight Systems

NASA Technical Reports Server (NTRS)

Sowards, Stephanie; Honeycutt, Timothy

2008-01-01

This paper discusses the benefits of conducting multi-system integration testing of space flight elements in lieu of merely shipping and shooting to the launch site and launching. "Ship and shoot" is a philosophy that proposes to transport flight elements directly from the factory to the launch site and begin the mission without further testing. Integration testing, relevant to validation testing in this context, is a risk mitigation effort that builds upon the individual element and system levels of qualification and acceptance tests, greatly improving the confidence of operations in space. The International Space Station Program (ISSP) experience is the focus of most discussions from a historical perspective, while proposed integration testing of the Constellation Program is also discussed. The latter will include Multi-Element Integration Testing (MElT) and Flight Element Integration Testing (FElT).

Transparent multi-zone crystal growth furnace and method for controlling the same

NASA Technical Reports Server (NTRS)

Batur, Celal (Inventor); Bennett, Robert J. (Inventor); Duval, Walter (Inventor)

2000-01-01

A crystal growth system, comprising: a furnace; a plurality of heating elements coupled to said furnace, each said plurality of heating elements defining a heat zone, each said heating element set to a desired temperature value; a plurality of thermocouples associated with respective heat zones to detect a temperature value; a translation system for passing an ampoule containing crystal growth material through said furnace into said heat zones and providing a positional location of said ampoule and; a multi-variable self-tuning temperature controller connected to said plurality of heating elements, said plurality of thermocouples and said translation system, said controller monitoring each said zone temperature value and upon considering the thermal interaction of heating zones and the moving thermal inertia of the ampoule, adjusting voltage input to said heat zones to obtain optimal crystal growth within said ampoule.

Transparent multi-zone crystal growth furnace and method for controlling the same

NASA Technical Reports Server (NTRS)

Batur, Celal (Inventor); Duval, Walter (Inventor); Bennett, Robert J. (Inventor)

2001-01-01

A crystal growth system, comprising: a furnace; a plurality of heating elements coupled to said furnace, each said plurality of heating elements defining a heat zone, each said heating element set to a desired temperature value; a plurality of thermocouples associated with respective heat zones to detect a temperature value; a translation system for passing an ampoule containing crystal growth material through said furnace into said heat zones and providing a positional location of said ampoule and; a multi-variable self-tuning temperature controller connected to said plurality of heating elements, said plurality of thermocouples and said translation system, said controller monitoring each said zone temperature value and upon considering the thermal interaction of heating zones and the moving thermal inertia of the ampoule, adjusting voltage input to said heat zones to obtain optimal crystal growth within said ampoule.

Inverse optimal self-tuning PID control design for an autonomous underwater vehicle

NASA Astrophysics Data System (ADS)

Rout, Raja; Subudhi, Bidyadhar

2017-01-01

This paper presents a new approach to path following control design for an autonomous underwater vehicle (AUV). A NARMAX model of the AUV is derived first and then its parameters are adapted online using the recursive extended least square algorithm. An adaptive Propotional-Integral-Derivative (PID) controller is developed using the derived parameters to accomplish the path following task of an AUV. The gain parameters of the PID controller are tuned using an inverse optimal control technique, which alleviates the problem of solving Hamilton-Jacobian equation and also satisfies an error cost function. Simulation studies were pursued to verify the efficacy of the proposed control algorithm. From the obtained results, it is envisaged that the proposed NARMAX model-based self-tuning adaptive PID control provides good path following performance even in the presence of uncertainty arising due to ocean current or hydrodynamic parameter.

Investigation of application of two-degree-of-freedom dry tuned-gimbal gyroscopes to strapdown navigation systems. [for use in VTOL aircraft

NASA Technical Reports Server (NTRS)

1974-01-01

The work is described which was accomplished during the investigation of the application of dry-tuned gimbal gyroscopes to strapdown navigation systems. A conventional strapdown configuration, employing analog electronics in conjunction with digital attitude and navigation computation, was examined using various levels of redundancy and both orthogonal and nonorthogonal sensor orientations. It is concluded that the cost and reliability performance constraints which had been established could not be met simultaneously with such a system. This conclusion led to the examination of an alternative system configuration which utilizes an essentially new strapdown system concept. This system employs all-digital signal processing in conjunction with the newly-developed large scale integration (LSI) electronic packaging techniques and a new two-degree-of-freedom dry tuned-gimbal instrument which is capable of providing both angular rate and acceleration information. Such a system is capable of exceeding the established performance goals.

The hierarchical expert tuning of PID controllers using tools of soft computing.

PubMed

Karray, F; Gueaieb, W; Al-Sharhan, S

2002-01-01

We present soft computing-based results pertaining to the hierarchical tuning process of PID controllers located within the control loop of a class of nonlinear systems. The results are compared with PID controllers implemented either in a stand alone scheme or as a part of conventional gain scheduling structure. This work is motivated by the increasing need in the industry to design highly reliable and efficient controllers for dealing with regulation and tracking capabilities of complex processes characterized by nonlinearities and possibly time varying parameters. The soft computing-based controllers proposed are hybrid in nature in that they integrate within a well-defined hierarchical structure the benefits of hard algorithmic controllers with those having supervisory capabilities. The controllers proposed also have the distinct features of learning and auto-tuning without the need for tedious and computationally extensive online systems identification schemes.

Programmable logic controller implementation of an auto-tuned predictive control based on minimal plant information.

PubMed

Valencia-Palomo, G; Rossiter, J A

2011-01-01

This paper makes two key contributions. First, it tackles the issue of the availability of constrained predictive control for low-level control loops. Hence, it describes how the constrained control algorithm is embedded in an industrial programmable logic controller (PLC) using the IEC 61131-3 programming standard. Second, there is a definition and implementation of a novel auto-tuned predictive controller; the key novelty is that the modelling is based on relatively crude but pragmatic plant information. Laboratory experiment tests were carried out in two bench-scale laboratory systems to prove the effectiveness of the combined algorithm and hardware solution. For completeness, the results are compared with a commercial proportional-integral-derivative (PID) controller (also embedded in the PLC) using the most up to date auto-tuning rules. Copyright © 2010 ISA. Published by Elsevier Ltd. All rights reserved.

Actively addressed single pixel full-colour plasmonic display

NASA Astrophysics Data System (ADS)

Franklin, Daniel; Frank, Russell; Wu, Shin-Tson; Chanda, Debashis

2017-05-01

Dynamic, colour-changing surfaces have many applications including displays, wearables and active camouflage. Plasmonic nanostructures can fill this role by having the advantages of ultra-small pixels, high reflectivity and post-fabrication tuning through control of the surrounding media. However, previous reports of post-fabrication tuning have yet to cover a full red-green-blue (RGB) colour basis set with a single nanostructure of singular dimensions. Here, we report a method which greatly advances this tuning and demonstrates a liquid crystal-plasmonic system that covers the full RGB colour basis set, only as a function of voltage. This is accomplished through a surface morphology-induced, polarization-dependent plasmonic resonance and a combination of bulk and surface liquid crystal effects that manifest at different voltages. We further demonstrate the system's compatibility with existing LCD technology by integrating it with a commercially available thin-film-transistor array. The imprinted surface interfaces readily with computers to display images as well as video.

Postfabrication Phase Error Correction of Silicon Photonic Circuits by Single Femtosecond Laser Pulses

DOE PAGES

Bachman, Daniel; Chen, Zhijiang; Wang, Christopher; ...

2016-11-29

Phase errors caused by fabrication variations in silicon photonic integrated circuits are an important problem, which negatively impacts device yield and performance. This study reports our recent progress in the development of a method for permanent, postfabrication phase error correction of silicon photonic circuits based on femtosecond laser irradiation. Using beam shaping technique, we achieve a 14-fold enhancement in the phase tuning resolution of the method with a Gaussian-shaped beam compared to a top-hat beam. The large improvement in the tuning resolution makes the femtosecond laser method potentially useful for very fine phase trimming of silicon photonic circuits. Finally, wemore » also show that femtosecond laser pulses can directly modify silicon photonic devices through a SiO 2 cladding layer, making it the only permanent post-fabrication method that can tune silicon photonic circuits protected by an oxide cladding.« less

Modelling and tuning for a time-delayed vibration absorber with friction

NASA Astrophysics Data System (ADS)

Zhang, Xiaoxu; Xu, Jian; Ji, Jinchen

2018-06-01

This paper presents an integrated analytical and experimental study to the modelling and tuning of a time-delayed vibration absorber (TDVA) with friction. In system modelling, this paper firstly applies the method of averaging to obtain the frequency response function (FRF), and then uses the derived FRF to evaluate the fitness of different friction models. After the determination of the system model, this paper employs the obtained FRF to evaluate the vibration absorption performance with respect to tunable parameters. A significant feature of the TDVA with friction is that its stability is dependent on the excitation parameters. To ensure the stability of the time-delayed control, this paper defines a sufficient condition for stability estimation. Experimental measurements show that the dynamic response of the TDVA with friction can be accurately predicted and the time-delayed control can be precisely achieved by using the modelling and tuning technique provided in this paper.

Nonlinear Adaptive PID Control for Greenhouse Environment Based on RBF Network

PubMed Central

Zeng, Songwei; Hu, Haigen; Xu, Lihong; Li, Guanghui

2012-01-01

This paper presents a hybrid control strategy, combining Radial Basis Function (RBF) network with conventional proportional, integral, and derivative (PID) controllers, for the greenhouse climate control. A model of nonlinear conservation laws of enthalpy and matter between numerous system variables affecting the greenhouse climate is formulated. RBF network is used to tune and identify all PID gain parameters online and adaptively. The presented Neuro-PID control scheme is validated through simulations of set-point tracking and disturbance rejection. We compare the proposed adaptive online tuning method with the offline tuning scheme that employs Genetic Algorithm (GA) to search the optimal gain parameters. The results show that the proposed strategy has good adaptability, strong robustness and real-time performance while achieving satisfactory control performance for the complex and nonlinear greenhouse climate control system, and it may provide a valuable reference to formulate environmental control strategies for actual application in greenhouse production. PMID:22778587

Learning and tuning fuzzy logic controllers through reinforcements.

PubMed

Berenji, H R; Khedkar, P

1992-01-01

A method for learning and tuning a fuzzy logic controller based on reinforcements from a dynamic system is presented. It is shown that: the generalized approximate-reasoning-based intelligent control (GARIC) architecture learns and tunes a fuzzy logic controller even when only weak reinforcement, such as a binary failure signal, is available; introduces a new conjunction operator in computing the rule strengths of fuzzy control rules; introduces a new localized mean of maximum (LMOM) method in combining the conclusions of several firing control rules; and learns to produce real-valued control actions. Learning is achieved by integrating fuzzy inference into a feedforward network, which can then adaptively improve performance by using gradient descent methods. The GARIC architecture is applied to a cart-pole balancing system and demonstrates significant improvements in terms of the speed of learning and robustness to changes in the dynamic system's parameters over previous schemes for cart-pole balancing.

Transposable elements re-wire and fine-tune the transcriptome.

PubMed

Cowley, Michael; Oakey, Rebecca J

2013-01-01

What good are transposable elements (TEs)? Although their activity can be harmful to host genomes and can cause disease, they nevertheless represent an important source of genetic variation that has helped shape genomes. In this review, we examine the impact of TEs, collectively referred to as the mobilome, on the transcriptome. We explore how TEs-particularly retrotransposons-contribute to transcript diversity and consider their potential significance as a source of small RNAs that regulate host gene transcription. We also discuss a critical role for the mobilome in engineering transcriptional networks, permitting coordinated gene expression, and facilitating the evolution of novel physiological processes.

Integrated Photonic Neural Probes for Patterned Brain Stimulation

DTIC Science & Technology

2017-08-14

two -photon imaging Task 3.2: In vivo demonstration of remote optical stimulation using photonic probes and multi -site electrical recording...have patterned nine e-pixels. We can individually address each e-pixel by tuning the color of the input light to the AWG. Figure (8) shows two ...Report: Integrated Photonic Neural Probes for Patterned Brain Stimulation The views , opinions and/or findings contained in this report are those of the

Enhanced robust fractional order proportional-plus-integral controller based on neural network for velocity control of permanent magnet synchronous motor.

PubMed

Zhang, Bitao; Pi, YouGuo

2013-07-01

The traditional integer order proportional-integral-differential (IO-PID) controller is sensitive to the parameter variation or/and external load disturbance of permanent magnet synchronous motor (PMSM). And the fractional order proportional-integral-differential (FO-PID) control scheme based on robustness tuning method is proposed to enhance the robustness. But the robustness focuses on the open-loop gain variation of controlled plant. In this paper, an enhanced robust fractional order proportional-plus-integral (ERFOPI) controller based on neural network is proposed. The control law of the ERFOPI controller is acted on a fractional order implement function (FOIF) of tracking error but not tracking error directly, which, according to theory analysis, can enhance the robust performance of system. Tuning rules and approaches, based on phase margin, crossover frequency specification and robustness rejecting gain variation, are introduced to obtain the parameters of ERFOPI controller. And the neural network algorithm is used to adjust the parameter of FOIF. Simulation and experimental results show that the method proposed in this paper not only achieve favorable tracking performance, but also is robust with regard to external load disturbance and parameter variation. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Tuning the Ignition Performance of a Microchip Initiator by Integrating Various Al/MoO3 Reactive Multilayer Films on a Semiconductor Bridge.

PubMed

Xu, Jianbing; Tai, Yu; Ru, Chengbo; Dai, Ji; Ye, Yinghua; Shen, Ruiqi; Zhu, Peng

2017-02-15

Reactive multilayer films (RMFs) can be integrated into semiconducting electronic structures with the use of microelectromechanical systems (MEMS) technology and represent potential applications in the advancement of microscale energy-demanding systems. In this study, aluminum/molybdenum trioxide (Al/MoO 3 )-based RMFs with different modulation periods were integrated on a semiconductor bridge (SCB) using a combination of an image reversal lift-off process and magnetron sputtering technology. This produced an energetic semiconductor bridge (ESCB)-chip initiator with controlled ignition performance. The effects of the Al/MoO 3 RMFs with different modulation periods on ignition properties of the ESCB initiator were then systematically investigated in terms of flame duration, maximum flame area, and the reaction ratio of the RMFs. These microchip initiators achieved flame durations of 60-600 μs, maximum flame areas of 2.85-17.61 mm 2 , and reaction ratios of ∼14-100% (discharged with 47 μF/30 V) by simply changing the modulation periods of the Al/MoO 3 RMFs. This behavior was also consistent with a one-dimensional diffusion reaction model. The microchip initiator exhibited a high level of integration and proved to have tuned ignition performance, which can potentially be used in civilian and military applications.

A computerized symbolic integration technique for development of triangular and quadrilateral composite shallow-shell finite elements

NASA Technical Reports Server (NTRS)

Anderson, C. M.; Noor, A. K.

1975-01-01

Computerized symbolic integration was used in conjunction with group-theoretic techniques to obtain analytic expressions for the stiffness, geometric stiffness, consistent mass, and consistent load matrices of composite shallow shell structural elements. The elements are shear flexible and have variable curvature. A stiffness (displacement) formulation was used with the fundamental unknowns consisting of both the displacement and rotation components of the reference surface of the shell. The triangular elements have six and ten nodes; the quadrilateral elements have four and eight nodes and can have internal degrees of freedom associated with displacement modes which vanish along the edges of the element (bubble modes). The stiffness, geometric stiffness, consistent mass, and consistent load coefficients are expressed as linear combinations of integrals (over the element domain) whose integrands are products of shape functions and their derivatives. The evaluation of the elemental matrices is divided into two separate problems - determination of the coefficients in the linear combination and evaluation of the integrals. The integrals are performed symbolically by using the symbolic-and-algebraic-manipulation language MACSYMA. The efficiency of using symbolic integration in the element development is demonstrated by comparing the number of floating-point arithmetic operations required in this approach with those required by a commonly used numerical quadrature technique.

The Obscure World of Integrative and Mobilizable Elements, Highly Widespread Elements that Pirate Bacterial Conjugative Systems

PubMed Central

Guédon, Gérard; Libante, Virginie; Coluzzi, Charles; Payot, Sophie

2017-01-01

Conjugation is a key mechanism of bacterial evolution that involves mobile genetic elements. Recent findings indicated that the main actors of conjugative transfer are not the well-known conjugative or mobilizable plasmids but are the integrated elements. This paper reviews current knowledge on “integrative and mobilizable elements” (IMEs) that have recently been shown to be highly diverse and highly widespread but are still rarely described. IMEs encode their own excision and integration and use the conjugation machinery of unrelated co-resident conjugative element for their own transfer. Recent studies revealed a much more complex and much more diverse lifecycle than initially thought. Besides their main transmission as integrated elements, IMEs probably use plasmid-like strategies to ensure their maintenance after excision. Their interaction with conjugative elements reveals not only harmless hitchhikers but also hunters that use conjugative elements as target for their integration or harmful parasites that subvert the conjugative apparatus of incoming elements to invade cells that harbor them. IMEs carry genes conferring various functions, such as resistance to antibiotics, that can enhance the fitness of their hosts and that contribute to their maintenance in bacterial populations. Taken as a whole, IMEs are probably major contributors to bacterial evolution. PMID:29165361

Magnesia tuned multi-walled carbon nanotubes–reinforced alumina nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, Iftikhar, E-mail: ifahmad@ksu.edu.sa; Islam, Mohammad; Dar, Mushtaq Ahmad

2015-01-15

Magnesia tuned alumina ceramic nanocomposites, reinforced with multi-walled carbon nanotubes, were condensed using pressureless and hot-press sintering processes. Densification, microstructure and mechanical properties of the produced nanocomposites were meticulously investigated. Electron microscopy studies revealed the homogenous carbon nanotube dispersion within the alumina matrix and confirmed the retention of carbon nanotubes' distinctive tubular morphology and nanoscale features during the extreme mixing/sintering processes. Pressureless sintered nanocomposites showed meagre mechanical responses due to the poorly-integrated microstructures with a slight improvement upon magnesia addition. Conversely, both the magnesia addition and application of hot-press sintering technique resulted in the nanocomposite formation with near-theoretical densities (~more » 99%), well-integrated microstructures and superior mechanical properties. Hot-press sintered nanocomposites incorporating 300 and 600 ppm magnesia exhibited an increase in hardness (10 and 11%), flexural strength (5 and 10%) and fracture toughness (15 and 20%) with respect to similar magnesia-free samples. Compared to monolithic alumina, a decent rise in fracture toughness (37%), flexural strength (22%) and hardness (20%) was observed in the hot-press sintered nanocomposites tuned with merely 600 ppm magnesia. Mechanically superior hot-press sintered magnesia tailored nanocomposites are attractive for several load-bearing structural applications. - Highlights: • MgO tailored Al{sub 2}O{sub 3}–2 wt.% CNT nanocomposites are presented. • The role of MgO and sintering on nanocomposite structures and properties was studied. • Well-dispersed CNTs maintained their morphology/structure after harsh sintering. • Hot-pressing and MgO led nanocomposites to higher properties/unified structures. • MgO tuned composites showed higher toughness (37%) and strength (22%) than Al{sub 2}O{sub 3}.« less

Improved functionality of graphene and carbon nanotube hybrid foam architecture by UV-ozone treatment

NASA Astrophysics Data System (ADS)

Wang, Wei; Ruiz, Isaac; Lee, Ilkeun; Zaera, Francisco; Ozkan, Mihrimah; Ozkan, Cengiz S.

2015-04-01

Optimization of the electrode/electrolyte double-layer interface is a key factor for improving electrode performance of aqueous electrolyte based supercapacitors (SCs). Here, we report the improved functionality of carbon materials via a non-invasive, high-throughput, and inexpensive UV generated ozone (UV-ozone) treatment. This process allows precise tuning of the graphene and carbon nanotube hybrid foam (GM) transitionally from ultrahydrophobic to hydrophilic within 60 s. The continuous tuning of surface energy can be controlled by simply varying the UV-ozone exposure time, while the ozone-oxidized carbon nanostructure maintains its integrity. Symmetric SCs based on the UV-ozone treated GM foam demonstrated enhanced rate performance. This technique can be readily applied to other CVD-grown carbonaceous materials by taking advantage of its ease of processing, low cost, scalability, and controllability.Optimization of the electrode/electrolyte double-layer interface is a key factor for improving electrode performance of aqueous electrolyte based supercapacitors (SCs). Here, we report the improved functionality of carbon materials via a non-invasive, high-throughput, and inexpensive UV generated ozone (UV-ozone) treatment. This process allows precise tuning of the graphene and carbon nanotube hybrid foam (GM) transitionally from ultrahydrophobic to hydrophilic within 60 s. The continuous tuning of surface energy can be controlled by simply varying the UV-ozone exposure time, while the ozone-oxidized carbon nanostructure maintains its integrity. Symmetric SCs based on the UV-ozone treated GM foam demonstrated enhanced rate performance. This technique can be readily applied to other CVD-grown carbonaceous materials by taking advantage of its ease of processing, low cost, scalability, and controllability. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06795a

BRIEF COMMUNICATION: Electrothermal bistability tuning in a large displacement micro actuator

NASA Astrophysics Data System (ADS)

Gerson, Y.; Krylov, S.; Ilic, B.

2010-11-01

We report on an approach allowing simple yet efficient tuning of the bistability properties in large displacement micro actuators. The devices fabricated from silicon on insulator (SOI) wafers using a deep reactive ion etching (DRIE)-based process incorporate elastic suspension realized as a pair of beams initially curved in-plane and are operated electrostatically by a comb-drive transducer. The curvature of beam and therefore the stability characteristics of the suspension are controlled by passing a current through the suspension and resistive heating the beam material. Experimental results, which are in good agreement with the finite elements model predictions, demonstrate the feasibility of the suggested approach and show that the application of a small tuning current increases the device deflection from 42 to 56 µm, allows adjustment of the critical snap-through and snap-back voltages and makes it possible the control of latching without an additional electrode. The approach can be efficiently implemented in electrical and optical switches and threshold inertial and mass sensors where the use of long displacement actuators with an adjustable bistability range is beneficial.

Filtering and polychromatic vision in mantis shrimps: themes in visible and ultraviolet vision.

PubMed

Cronin, Thomas W; Bok, Michael J; Marshall, N Justin; Caldwell, Roy L

2014-01-01

Stomatopod crustaceans have the most complex and diverse assortment of retinal photoreceptors of any animals, with 16 functional classes. The receptor classes are subdivided into sets responsible for ultraviolet vision, spatial vision, colour vision and polarization vision. Many of these receptor classes are spectrally tuned by filtering pigments located in photoreceptors or overlying optical elements. At visible wavelengths, carotenoproteins or similar substances are packed into vesicles used either as serial, intrarhabdomal filters or lateral filters. A single retina may contain a diversity of these filtering pigments paired with specific photoreceptors, and the pigments used vary between and within species both taxonomically and ecologically. Ultraviolet-filtering pigments in the crystalline cones serve to tune ultraviolet vision in these animals as well, and some ultraviolet receptors themselves act as birefringent filters to enable circular polarization vision. Stomatopods have reached an evolutionary extreme in their use of filter mechanisms to tune photoreception to habitat and behaviour, allowing them to extend the spectral range of their vision both deeper into the ultraviolet and further into the red.

Efficient hydrogen evolution catalysis using ternary pyrite-type cobalt phosphosulphide

NASA Astrophysics Data System (ADS)

Cabán-Acevedo, Miguel; Stone, Michael L.; Schmidt, J. R.; Thomas, Joseph G.; Ding, Qi; Chang, Hung-Chih; Tsai, Meng-Lin; He-Hau, Jr.; Jin, Song

2015-12-01

The scalable and sustainable production of hydrogen fuel through water splitting demands efficient and robust Earth-abundant catalysts for the hydrogen evolution reaction (HER). Building on promising metal compounds with high HER catalytic activity, such as pyrite structure cobalt disulphide (CoS2), and substituting non-metal elements to tune the hydrogen adsorption free energy could lead to further improvements in catalytic activity. Here we present a combined theoretical and experimental study to establish ternary pyrite-type cobalt phosphosulphide (CoPS) as a high-performance Earth-abundant catalyst for electrochemical and photoelectrochemical hydrogen production. Nanostructured CoPS electrodes achieved a geometrical catalytic current density of 10 mA cm-2 at overpotentials as low as 48 mV, with outstanding long-term operational stability. Integrated photocathodes of CoPS on n+-p-p+ silicon micropyramids achieved photocurrents up to 35 mA cm-2 at 0 V versus the reversible hydrogen electrode (RHE), onset photovoltages as high as 450 mV versus RHE, and the most efficient solar-driven hydrogen generation from Earth-abundant systems.

MEMS resonant load cells for micro-mechanical test frames: feasibility study and optimal design

NASA Astrophysics Data System (ADS)

Torrents, A.; Azgin, K.; Godfrey, S. W.; Topalli, E. S.; Akin, T.; Valdevit, L.

2010-12-01

This paper presents the design, optimization and manufacturing of a novel micro-fabricated load cell based on a double-ended tuning fork. The device geometry and operating voltages are optimized for maximum force resolution and range, subject to a number of manufacturing and electromechanical constraints. All optimizations are enabled by analytical modeling (verified by selected finite elements analyses) coupled with an efficient C++ code based on the particle swarm optimization algorithm. This assessment indicates that force resolutions of ~0.5-10 nN are feasible in vacuum (~1-50 mTorr), with force ranges as large as 1 N. Importantly, the optimal design for vacuum operation is independent of the desired range, ensuring versatility. Experimental verifications on a sub-optimal device fabricated using silicon-on-glass technology demonstrate a resolution of ~23 nN at a vacuum level of ~50 mTorr. The device demonstrated in this article will be integrated in a hybrid micro-mechanical test frame for unprecedented combinations of force resolution and range, displacement resolution and range, optical (or SEM) access to the sample, versatility and cost.

A measurement of global event shape distributions in the hadronic decays of the Z 0

NASA Astrophysics Data System (ADS)

Akrawy, M. Z.; Alexander, G.; Allison, J.; Allport, P. P.; Anderson, K. J.; Armitage, J. C.; Arnison, G. T. J.; Ashton, P.; Azuelos, G.; Baines, J. T. M.; Ball, A. H.; Banks, J.; Barker, G. J.; Barlow, R. J.; Batley, J. R.; Becker, J.; Behnke, T.; Bell, K. W.; Bella, G.; Bethke, S.; Biebel, O.; Binder, U.; Bloodworth, L. J.; Bock, P.; Breuker, H.; Brown, R. M.; Brun, R.; Buijs, A.; Burckhart, H. J.; Capiluppi, P.; Carnegie, R. K.; Carter, A. A.; Carter, J. R.; Chang, C. Y.; Charlton, D. G.; Chrin, J. T. M.; Cohen, I.; Collins, W. J.; Conboy, J. E.; Couch, M.; Coupland, M.; Cuffiani, M.; Dado, S.; Dallavalle, G. M.; Debu, P.; Deninno, M. M.; Dieckmann, A.; Dittmar, M.; Dixit, M. S.; Duchovni, E.; Duerdoth, I. P.; Dumas, D.; El Mamouni, H.; Elcombe, P. A.; Estabrooks, P. G.; Etzion, E.; Fabbri, F.; Farthouat, P.; Fischer, H. M.; Fong, D. G.; French, M. T.; Fukunaga, C.; Gaidot, A.; Ganel, O.; Gary, J. W.; Gascon, J.; Geddes, N. I.; Gee, C. N. P.; Geich-Gimbel, C.; Gensler, S. W.; Gentit, F. X.; Giacomelli, G.; Gibson, V.; Gibson, W. R.; Gillies, J. D.; Goldberg, J.; Goodrick, M. J.; Gorn, W.; Granite, D.; Gross, E.; Grosse-Wiesmann, P.; Grunhaus, J.; Hagedorn, H.; Hagemann, J.; Hansroul, M.; Hargrove, C. K.; Hart, J.; Hattersley, P. M.; Hauschild, M.; Hawkes, C. M.; Heflin, E.; Hemingway, R. J.; Heuer, R. D.; Hill, J. C.; Hillier, S. J.; Ho, C.; Hobbs, J. D.; Hobson, P. R.; Hochman, D.; Holl, B.; Homer, R. J.; Hou, S. R.; Howarth, C. P.; Hughes-Jones, R. E.; Igo-Kemenes, P.; Ihssen, H.; Imrie, D. C.; Jawahery, A.; Jeffreys, P. W.; Jeremie, H.; Jimack, M.; Jobes, M.; Jones, R. W. L.; Jovanovic, P.; Karlen, D.; Kawagoe, K.; Kawamoto, T.; Kellogg, R. G.; Kennedy, B. W.; Kleinwort, C.; Klem, D. E.; Knop, G.; Kobayashi, T.; Kokott, T. P.; Köpke, L.; Kowalewski, R.; Kreutzmann, H.; von Krogh, J.; Kroll, J.; Kuwano, M.; Kyberd, P.; Lafferty, G. D.; Lamarche, F.; Larson, W. J.; Lasota, M. M. B.; Layter, J. G.; Le Du, P.; Leblanc, P.; Lee, A. M.; Lellouch, D.; Lennert, P.; Lessard, L.; Levinson, L.; Lloyd, S. L.; Loebinger, F. K.; Lorah, J. M.; Lorazo, B.; Losty, M. J.; Ludwig, J.; Lupu, N.; Ma, J.; MacBeth, A. A.; Mannelli, M.; Marcellini, S.; Maringer, G.; Martin, A. J.; Martin, J. P.; Mashimo, T.; Mättig, P.; Maur, U.; McMahon, T. J.; McPherson, A. C.; Meijers, F.; Menszner, D.; Merritt, F. S.; Mes, H.; Michelini, A.; Middleton, R. P.; Mikenberg, G.; Miller, D. J.; Milstene, C.; Minowa, M.; Mohr, W.; Montanari, A.; Mori, T.; Moss, M. W.; Murphy, P. G.; Murray, W. J.; Nellen, B.; Nguyen, H. H.; Nozaki, M.; O'Dowd, A. J. P.; O'Neale, S. W.; O'Neill, B. P.; Oakham, F. G.; Odorici, F.; Ogg, M.; Oh, H.; Oreglia, M. J.; Orito, S.; Pansart, J. P.; Patrick, G. N.; Pawley, S. J.; Pfister, P.; Pilcher, J. E.; Pinfold, J. L.; Plane, D. E.; Poli, B.; Pouladdej, A.; Pritchard, P. W.; Quast, G.; Raab, J.; Redmond, M. W.; Rees, D. L.; Regimbald, M.; Riles, K.; Roach, C. M.; Robins, S. A.; Rollnik, A.; Roney, J. M.; Rossberg, S.; Rossi, A. M.; Routenburg, P.; Runge, K.; Runolfsson, O.; Sanghera, S.; Sansum, R. A.; Sasaki, M.; Saunders, B. J.; Schaile, A. D.; Schaile, O.; Schappert, W.; Scharff-Hansen, P.; von der Schmitt, H.; Schreiber, S.; Schwarz, J.; Shapira, A.; Shen, B. C.; Sherwood, P.; Simon, A.; Siroli, G. P.; Skuja, A.; Smith, A. M.; Smith, T. J.; Snow, G. A.; Spreadbury, E. J.; Springer, R. W.; Sproston, M.; Stephens, K.; Stier, H. E.; Ströhmer, R.; Strom, D.; Takeda, H.; Takeshita, T.; Tsukamoto, T.; Turner, M. F.; Tysarczyk-Niemeyer, G.; van den Plas, D.; Vandalen, G. J.; Vasseur, G.; Virtue, C. J.; Wagner, A.; Wahl, C.; Ward, C. P.; Ward, D. R.; Waterhouse, J.; Watkins, P. M.; Watson, A. T.; Watson, N. K.; Weber, M.; Weisz, S.; Wermes, N.; Weymann, M.; Wilson, G. W.; Wilson, J. A.; Wingerter, I.; Winterer, V.-H.; Wood, N. C.; Wotton, S.; Wuensch, B.; Wyatt, T. R.; Yaari, R.; Yang, Y.; Yekutieli, G.; Yoshida, T.; Zeuner, W.; Zorn, G. T.

1990-12-01

We present measurements of global event shape distributions in the hadronic decays of the Z 0. The data sample, corresponding to an integrated luminosity of about 1.3 pb-1, was collected with the OPAL detector at LEP. Most of the experimental distributions we present are unfolded for the finite acceptance and resolution of the OPAL detector. Through comparison with our unfolded data, we tune the parameter values of several Monte Carlo computer programs which simulate perturbative QCD and the hadronization of partons. Jetset version 7.2, Herwig version 3.4 and Ariadne version 3.1 all provide good descriptions of the experimental distributions. They in addition describe lower energy data with the parameter values adjusted at the Z 0 energy. A complete second order matrix element Monte Carlo program with a modified perturbation scale is also compared to our 91 GeV data and its parameter values are adjusted. We obtained an unfolded value for the mean charged multiplicity of 21.28±0.04±0.84, where the first error is statistical and the second is systematic.

Performance of an on-chip superconducting circulator for quantum microwave systems

NASA Astrophysics Data System (ADS)

Chapman, Benjamin; Rosenthal, Eric; Moores, Bradley; Kerckhoff, Joseph; Mates, J. A. B.; Hilton, G. C.; Vale, L. R.; Ullom, J. N.; LalumíEre, Kevin; Blais, Alexandre; Lehnert, K. W.

Microwave circulators enforce a single propagation direction for signals in an electrical network. Unfortunately, commercial circulators are bulky, lossy, and cannot be integrated close to superconducting circuits because they require strong ( kOe) magnetic fields produced by permanent magnets. Here we report on the performance of an on-chip, active circulator for superconducting microwave circuits, which uses no permanent magnets. Non-reciprocity is achieved by actively modulating reactive elements around 100 MHz, giving roughly a factor of 50 in the separation between signal and control frequencies, which facilitates filtering. The circulator's active components are dynamically tunable inductors constructed with arrays of dc-SQUIDs in series. Array inductance is tuned by varying the magnetic flux through the SQUIDs with fields weaker than 1 Oe. Although the instantaneous bandwidth of the device is narrow, the operation frequency is tunable between 4 and 8 GHz. This presentation will describe the device's theory of operation and compare its measured performance to design goals. This work is supported by the ARO under contract W911NF-14-1-0079 and the National Science Foundation under Grant Number 1125844.

High frequency inductive lamp and power oscillator

DOEpatents

MacLennan, Donald A.; Turner, Brian P.; Dolan, James T.; Kirkpatrick, Douglas A.; Leng, Yongzhang

2000-01-01

A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and/or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency. Various control circuits may be employed to match the driving frequency of the oscillator to a plurality of tuning states of the lamp.

From SED HI concept to Pleiades FM detection unit measurements

NASA Astrophysics Data System (ADS)

Renard, Christophe; Dantes, Didier; Neveu, Claude; Lamard, Jean-Luc; Oudinot, Matthieu; Materne, Alex

2017-11-01

The first flight model PLEIADES high resolution instrument under Thales Alenia Space development, on behalf of CNES, is currently in integration and test phases. Based on the SED HI detection unit concept, PLEIADES detection unit has been fully qualified before the integration at telescope level. The main radiometric performances have been measured on engineering and first flight models. This paper presents the results of performances obtained on the both models. After a recall of the SED HI concept, the design and performances of the main elements (charge coupled detectors, focal plane and video processing unit), detection unit radiometric performances are presented and compared to the instrument specifications for the panchromatic and multispectral bands. The performances treated are the following: - video signal characteristics, - dark signal level and dark signal non uniformity, - photo-response non uniformity, - non linearity and differential non linearity, - temporal and spatial noises regarding system definitions PLEIADES detection unit allows tuning of different functions: reference and sampling time positioning, anti-blooming level, gain value, TDI line number. These parameters are presented with their associated criteria of optimisation to achieve system radiometric performances and their sensitivities on radiometric performances. All the results of the measurements performed by Thales Alenia Space on the PLEIADES detection units demonstrate the high potential of the SED HI concept for Earth high resolution observation system allowing optimised performances at instrument and satellite levels.

Optical design considerations for high-concentration photovoltaics

NASA Astrophysics Data System (ADS)

Garboushian, Vahan; Gordon, Robert

2006-08-01

Over the past 15 years, major advances in Concentrating Photovoltaics (CPV) have been achieved. Ultra-efficient Si solar cells have produced commercial concentration systems which are being fielded today and are competitively priced. Advanced research has primarily focused on significantly more efficient multi-junction solar cells for tomorrow's systems. This effort has produced sophisticated solar cells that significantly improve power production. Additional performance and cost improvements, especially in the optical system area and system integration, must be made before CPV can realize its ultimate commercial potential. Structural integrity and reliability are vital for commercial success. As incremental technical improvements are made in solar cell technologies, evaluation and 'fine-tuning' of optical systems properly matched to the solar cell are becoming increasingly necessary. As we move forward, it is increasingly important to optimize all of the interrelated elements of a CPV system for high performance without sacrificing the marketable cost and structural requirements of the system. Areas such as wavelength absorption of refractive optics need to be carefully matched to the solar cell technology employed. Reflective optics require advanced engineering models to insure uniform flux distribution without excessive losses. In Situ measurement of the 'fine-grain' improvements are difficult as multiple variables such as solar insolation, temperature, wind, altitude, etc. infringe on analytical data. This paper discusses design considerations based on 10 years of field trials of high concentration systems and their relevance for tomorrow's advanced CPV systems.

Technical Operations (TOPS) IV Task Order 0003: Responsive Interface for Transport Tuning (RITT)

DTIC Science & Technology

2016-05-29

on the further development of artificial hair sensors (AHS) featuring a responsive carbon nanotube (CNT) array to serve as a piezoresistive element...under separate cover, as AFRL Interim Report AFRL-RX-WP-TR-2016-0071 dated 30 October 2015. 15. SUBJECT TERMS artificial hair sensor, carbon... Hair Sensors: Fabrication and Model Parameterization .......................... 4 3.1.1 Introduction

Semi-active compressor valve

DOEpatents

Brun, Klaus; Gernentz, Ryan S.

2010-07-27

A method and system for fine-tuning the motion of suction or discharge valves associated with cylinders of a reciprocating gas compressor, such as the large compressors used for natural gas transmission. The valve's primary driving force is conventional, but the valve also uses an electromagnetic coil to sense position of the plate (or other plugging element) and to provide an opposing force prior to impact.

High-performance silicon photonic tri-state switch based on balanced nested Mach-Zehnder interferometer.

PubMed

Lu, Zeqin; Celo, Dritan; Mehrvar, Hamid; Bernier, Eric; Chrostowski, Lukas

2017-09-25

This work proposes a novel silicon photonic tri-state (cross/bar/blocking) switch, featuring high-speed switching, broadband operation, and crosstalk-free performance. The switch is designed based on a 2 × 2 balanced nested Mach-Zehnder interferometer structure with carrier injection phase tuning. As compared to silicon photonic dual-state (cross/bar) switches based on Mach-Zehnder interferometers with carrier injection phase tuning, the proposed switch not only has better performance in cross/bar switching but also provides an extra blocking state. The unique blocking state has a great advantage in applications of N × N switch fabrics, where idle switching elements in the fabrics can be configured to the blocking state for crosstalk suppression. According to our numerical experiments on a fully loaded 8 × 8 dilated Banyan switch fabric, the worst output crosstalk of the 8 × 8 switch can be dramatically suppressed by more than 50 dB, by assigning the blocking state to idle switching elements in the fabric. The results of this work can extend the functionality of silicon photonic switches and significantly improve the performance of on-chip N × N photonic switching technologies.

The development and testing of the thermal break divertor monoblock target design delivering 20 MW m-2 heat load capability

NASA Astrophysics Data System (ADS)

Fursdon, M.; Barrett, T.; Domptail, F.; Evans, Ll M.; Luzginova, N.; Greuner, N. H.; You, J.-H.; Li, M.; Richou, M.; Gallay, F.; Visca, E.

2017-12-01

The design and development of a novel plasma facing component (for fusion power plants) is described. The component uses the existing ‘monoblock’ construction which consists of a tungsten ‘block’ joined via a copper interlayer to a through CuCrZr cooling pipe. In the new concept the interlayer stiffness and conductivity properties are tuned so that stress in the principal structural element of the component (the cooling pipe) is reduced. Following initial trials with off-the-shelf materials, the concept was realized by machined features in an otherwise solid copper interlayer. The shape and distribution of the features were tuned by finite element analyses subject to ITER structural design criterion in-vessel components (SDC-IC) design rules. Proof of concept mock-ups were manufactured using a two stage brazing process verified by tomography and micrographic inspection. Full assemblies were inspected using ultrasound and thermographic (SATIR) test methods at ENEA and CEA respectively. High heat flux tests using IPP’s GLADIS facility showed that 200 cycles at 20 MW m-2 and five cycles at 25 MW m-2 could be sustained without apparent component damage. Further testing and component development is planned.

Optimizing qPlus sensor assemblies for simultaneous scanning tunneling and noncontact atomic force microscopy operation based on finite element method analysis

DOE PAGES

Dagdeviren, Omur E.; Schwarz, Udo D.

2017-03-20

Quartz tuning forks that have a probe tip attached to the end of one of its prongs while the other prong is arrested to a holder (“qPlus” configuration) have gained considerable popularity in recent years for high-resolution atomic force microscopy imaging. The small size of the tuning forks and the complexity of the sensor architecture, however, often impede predictions on how variations in the execution of the individual assembly steps affect the performance of the completed sensor. Extending an earlier study that provided numerical analysis of qPlus-style setups without tips, this work quantifies the influence of tip attachment on themore » operational characteristics of the sensor. The results using finite element modeling show in particular that for setups that include a metallic tip that is connected via a separate wire to enable the simultaneous collection of local forces and tunneling currents, the exact realization of this wire connection has a major effect on sensor properties such as spring constant, quality factor, resonance frequency, and its deviation from an ideal vertical oscillation.« less

Optimizing qPlus sensor assemblies for simultaneous scanning tunneling and noncontact atomic force microscopy operation based on finite element method analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dagdeviren, Omur E.; Schwarz, Udo D.

Quartz tuning forks that have a probe tip attached to the end of one of its prongs while the other prong is arrested to a holder (“qPlus” configuration) have gained considerable popularity in recent years for high-resolution atomic force microscopy imaging. The small size of the tuning forks and the complexity of the sensor architecture, however, often impede predictions on how variations in the execution of the individual assembly steps affect the performance of the completed sensor. Extending an earlier study that provided numerical analysis of qPlus-style setups without tips, this work quantifies the influence of tip attachment on themore » operational characteristics of the sensor. The results using finite element modeling show in particular that for setups that include a metallic tip that is connected via a separate wire to enable the simultaneous collection of local forces and tunneling currents, the exact realization of this wire connection has a major effect on sensor properties such as spring constant, quality factor, resonance frequency, and its deviation from an ideal vertical oscillation.« less

Multi-frequency modes in superconducting resonators: Bridging frequency gaps in off-resonant couplings

NASA Astrophysics Data System (ADS)

Andersen, Christian Kraglund; Mølmer, Klaus

2015-03-01

A SQUID inserted in a superconducting waveguide resonator imposes current and voltage boundary conditions that makes it suitable as a tuning element for the resonator modes. If such a SQUID element is subject to a periodically varying magnetic flux, the resonator modes acquire frequency side bands. We calculate the multi-frequency eigenmodes and these can couple resonantly to physical systems with different transition frequencies and this makes the resonator an efficient quantum bus for state transfer and coherent quantum operations in hybrid quantum systems. As an example of the application, we determine their coupling to transmon qubits with different frequencies and we present a bi-chromatic scheme for entanglement and gate operations. In this calculation, we obtain a maximally entangled state with a fidelity F = 95 % . Our proposal is competitive with the achievements of other entanglement-gates with superconducting devices and it may offer some advantages: (i) There is no need for additional control lines and dephasing associated with the conventional frequency tuning of qubits. (ii) When our qubits are idle, they are far detuned with respect to each other and to the resonator, and hence they are immune to cross talk and Purcell-enhanced decay.

Goldilocks and the three inorganic equilibria: how Earth's chemistry and life coevolve to be nearly in tune.

PubMed

Rickaby, R E M

2015-03-13

Life and the chemical environment are united in an inescapable feedback cycle. The periodic table of the elements essential for life has transformed over Earth's history, but, as today, evolved in tune with the elements available in abundance in the environment. The most revolutionary time in life's history was the advent and proliferation of oxygenic photosynthesis which forced the environment towards a greater degree of oxidation. Consideration of three inorganic chemical equilibria throughout this gradual oxygenation prescribes a phased release of trace metals to the environment, which appear to have coevolved with employment of these new chemicals by life. Evolution towards complexity was chemically constrained, and changes in availability of notably Fe, Zn and Cu paced the systematic development of complex organisms. Evolving life repeatedly catalysed its own chemical challenges via the unwitting release of new and initially toxic chemicals. Ultimately, the harnessing of these allowed life to advance to greater complexity, though the mechanism responsible for translating novel chemistry to heritable use remains elusive. Whether a chemical acts as a poison or a nutrient lies both in the dose and in its environmental history. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Electronic Switch Arrays for Managing Microbattery Arrays

NASA Technical Reports Server (NTRS)

Mojarradi, Mohammad; Alahmad, Mahmoud; Sukumar, Vinesh; Zghoul, Fadi; Buck, Kevin; Hess, Herbert; Li, Harry; Cox, David

2008-01-01

Integrated circuits have been invented for managing the charging and discharging of such advanced miniature energy-storage devices as planar arrays of microscopic energy-storage elements [typically, microscopic electrochemical cells (microbatteries) or microcapacitors]. The architecture of these circuits enables implementation of the following energy-management options: dynamic configuration of the elements of an array into a series or parallel combination of banks (subarrarys), each array comprising a series of parallel combination of elements; direct addressing of individual banks for charging/or discharging; and, disconnection of defective elements and corresponding reconfiguration of the rest of the array to utilize the remaining functional elements to obtain the desited voltage and current performance. An integrated circuit according to the invention consists partly of a planar array of field-effect transistors that function as switches for routing electric power among the energy-storage elements, the power source, and the load. To connect the energy-storage elements to the power source for charging, a specific subset of switches is closed; to connect the energy-storage elements to the load for discharging, a different specific set of switches is closed. Also included in the integrated circuit is circuitry for monitoring and controlling charging and discharging. The control and monitoring circuitry, the switching transistors, and interconnecting metal lines are laid out on the integrated-circuit chip in a pattern that registers with the array of energy-storage elements. There is a design option to either (1) fabricate the energy-storage elements in the corresponding locations on, and as an integral part of, this integrated circuit; or (2) following a flip-chip approach, fabricate the array of energy-storage elements on a separate integrated-circuit chip and then align and bond the two chips together.

Probing low noise at the MOS interface with a spin-orbit qubit.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jock, Ryan Michael; Jacobson, Noah Tobias; Harvey-Collard, Patrick

The silicon metal-oxide-semiconductor (MOS) material system is technologically important for the implementation of electron spin-based quantum information technologies. Researchers predict the need for an integrated platform in order to implement useful computation, and decades of advancements in silicon microelectronics fabrication lends itself to this challenge. However, fundamental concerns have been raised about the MOS interface (e.g. trap noise, variations in electron g-factor and practical implementation of multi-QDs). Furthermore, two-axis control of silicon qubits has, to date, required the integration of non-ideal components (e.g. microwave strip-lines, micro-magnets, triple quantum dots, or introduction of donor atoms). In this paper, we introduce amore » spin-orbit (SO) driven singlet- triplet (ST) qubit in silicon, demonstrating all-electrical two-axis control that requires no additional integrated elements and exhibits charge noise properties equivalent to other more model, but less commercially mature, semiconductor systems. We demonstrate the ability to tune an intrinsic spin-orbit interface effect, which is consistent with Rashba and Dresselhaus contributions that are remarkably strong for a low spin-orbit material such as silicon. The qubit maintains the advantages of using isotopically enriched silicon for producing a quiet magnetic environment, measuring spin dephasing times of 1.6 μs using 99.95% 28Si epitaxy for the qubit, comparable to results from other isotopically enhanced silicon ST qubit systems. This work, therefore, demonstrates that the interface inherently provides properties for two-axis control, and the technologically important MOS interface does not add additional detrimental qubit noise. isotopically enhanced silicon ST qubit systems« less

A conformal mapping based fractional order approach for sub-optimal tuning of PID controllers with guaranteed dominant pole placement

NASA Astrophysics Data System (ADS)

Saha, Suman; Das, Saptarshi; Das, Shantanu; Gupta, Amitava

2012-09-01

A novel conformal mapping based fractional order (FO) methodology is developed in this paper for tuning existing classical (Integer Order) Proportional Integral Derivative (PID) controllers especially for sluggish and oscillatory second order systems. The conventional pole placement tuning via Linear Quadratic Regulator (LQR) method is extended for open loop oscillatory systems as well. The locations of the open loop zeros of a fractional order PID (FOPID or PIλDμ) controller have been approximated in this paper vis-à-vis a LQR tuned conventional integer order PID controller, to achieve equivalent integer order PID control system. This approach eases the implementation of analog/digital realization of a FOPID controller with its integer order counterpart along with the advantages of fractional order controller preserved. It is shown here in the paper that decrease in the integro-differential operators of the FOPID/PIλDμ controller pushes the open loop zeros of the equivalent PID controller towards greater damping regions which gives a trajectory of the controller zeros and dominant closed loop poles. This trajectory is termed as "M-curve". This phenomena is used to design a two-stage tuning algorithm which reduces the existing PID controller's effort in a significant manner compared to that with a single stage LQR based pole placement method at a desired closed loop damping and frequency.

Efficient receiver tuning using differential evolution strategies

NASA Astrophysics Data System (ADS)

Wheeler, Caleb H.; Toland, Trevor G.

2016-08-01

Differential evolution (DE) is a powerful and computationally inexpensive optimization strategy that can be used to search an entire parameter space or to converge quickly on a solution. The Kilopixel Array Pathfinder Project (KAPPa) is a heterodyne receiver system delivering 5 GHz of instantaneous bandwidth in the tuning range of 645-695 GHz. The fully automated KAPPa receiver test system finds optimal receiver tuning using performance feedback and DE. We present an adaptation of DE for use in rapid receiver characterization. The KAPPa DE algorithm is written in Python 2.7 and is fully integrated with the KAPPa instrument control, data processing, and visualization code. KAPPa develops the technologies needed to realize heterodyne focal plane arrays containing 1000 pixels. Finding optimal receiver tuning by investigating large parameter spaces is one of many challenges facing the characterization phase of KAPPa. This is a difficult task via by-hand techniques. Characterizing or tuning in an automated fashion without need for human intervention is desirable for future large scale arrays. While many optimization strategies exist, DE is ideal for time and performance constraints because it can be set to converge to a solution rapidly with minimal computational overhead. We discuss how DE is utilized in the KAPPa system and discuss its performance and look toward the future of 1000 pixel array receivers and consider how the KAPPa DE system might be applied.

Single-particle dynamics in a nonlinear accelerator lattice: attaining a large tune spread with octupoles in IOTA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antipov, S. A.; Nagaitsev, S.; Valishev, A.

2017-04-01

Fermilab is constructing the Integrable Optics Test Accelerator (IOTA) as the centerpiece of the Accelerator R&D Program towards high-intensity circular machines. One of the factors limiting the beam intensity in present circular accelerators is collective instabilities, which can be suppressed by a spread of betatron frequencies (tunes) through the Landau damping mechanism or by an external damper, if the instability is slow enough. The spread is usually created by octupole magnets, which introduce the tune dependence on the amplitude and, in some cases, by a chromatic spread (tune dependence on particle's momentum). The introduction of octupoles usually lead to amore » resonant behavior and a reduction of the dynamic aperture. One of the goals of the IOTA research program is to achieve a high betatron tune spread, while retaining a large dynamic aperture using conventional octupole magnets in a special but realistic accelerator configuration. In this report, we present results of computer simulations of an electron beam in the IOTA by particle tracking and the Frequency Map Analysis. The results show that the ring's octupole magnets can be configured to provide a betatron tune shift of 0.08 (for particles at large amplitudes) with the dynamical aperture of over 20 beam sigma for a 150-MeV electron beam. The influence of the synchrotron motion, lattice errors, and magnet imperfections is insignificant for the parameters and levels of tolerances set by the design of the ring. The described octupole insert could be beneficial for suppression of space-charge induced instabilities in high intensity machines.« less

Tamm plasmon sub-wavelength structuration for loss reduction and resonance tuning

NASA Astrophysics Data System (ADS)

Gubaydullin, A. R.; Symonds, C.; Benoit, J.-M.; Ferrier, L.; Benyattou, T.; Jamois, C.; Lemaître, A.; Senellart, P.; Kaliteevski, M. A.; Bellessa, J.

2017-12-01

We have demonstrated experimentally and theoretically that losses in Tamm plasmon structures can be reduced by using a subwavelength structuration of the metal layer. The structures consist of a GaAs/Al0.95Ga0.05As Bragg reflector covered with a sub-wavelength silver grating. An active quantum dot layer is inserted to perform photoluminescence experiments. Experimental results show that the quality factor of the Tamm plasmon mode with grating increases substantially, with respect to the same structure without a grating. Moreover, a fine-tuning of the Tamm spectral position is obtained by changing the grating parameters. Finite element method simulations are in good agreement with the experimental values. Our results will promote the realization of lasing with the TP based devices at room temperature.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mammen, Nisha; Spanu, Leonardo; Tyo, Eric C.

Having the ability to tune the oxidation state of Cu nanoparticles is essential for their utility as catalysts. The degree of oxidation that maximizes product yield and selectivity is known to vary, depending on the particular reaction. Using first principles calculations and XANES measurements, we show that for subnanometer sizes in the gas phase, smaller Cu clusters are more resistant to oxidation. However, this trend is reversed upon deposition on an alumina support. We are able to explain this result in terms of strong cluster-support interactions, which differ significantly for the oxidized and elemental clusters. The stable cluster phases alsomore » feature novel oxygen stoichiometries. Our results suggest that one can tune the degree of oxidation of Cu catalysts by optimizing not just their size, but also the support they are deposited on.« less

Tuning the Catalytic Activity of Subcellular Nanoreactors.

PubMed

Jakobson, Christopher M; Chen, Yiqun; Slininger, Marilyn F; Valdivia, Elias; Kim, Edward Y; Tullman-Ercek, Danielle

2016-07-31

Bacterial microcompartments are naturally occurring subcellular organelles of bacteria and serve as a promising scaffold for the organization of heterologous biosynthetic pathways. A critical element in the design of custom biosynthetic organelles is quantitative control over the loading of heterologous enzymes to the interior of the organelles. We demonstrate that the loading of heterologous proteins to the 1,2-propanediol utilization microcompartment of Salmonella enterica can be controlled using two strategies: by modulating the transcriptional activation of the microcompartment container and by coordinating the expression of the microcompartment container and the heterologous cargo. These strategies allow general control over the loading of heterologous proteins localized by two different N-terminal targeting peptides and represent an important step toward tuning the catalytic activity of bacterial microcompartments for increased biosynthetic productivity. Copyright © 2016. Published by Elsevier Ltd.

Calcium doped MAPbI3 with better energy state alignment in perovskite solar cells

NASA Astrophysics Data System (ADS)

Lu, Chaojie; Zhang, Jing; Hou, Dagang; Gan, Xinlei; Sun, Hongrui; Zeng, Zhaobing; Chen, Renjie; Tian, Hui; Xiong, Qi; Zhang, Ying; Li, Yuanyuan; Zhu, Yuejin

2018-05-01

The organic-inorganic perovskite material with better energy alignment in the solar cell device will have a profound impact on the solar cell performance. It is valuable to tune the energy states by element substitution and doping in perovskites. Here, we present that Ca2+ is incorporated into CH3NH3PbI3, which up-shifts the valence band maximum and the conduction band minimum, leading to a difference between the bandgap and the Fermi level in the device. Consequently, Ca2+ incorporation results in an enhancement of the photovoltage and photocurrent, achieving a summit efficiency of 18.3% under standard 1 sun (AM 1.5). This work reveals the doped perovskite to improve the solar cell performance by tuning the energy state.

Space station architectural elements model study

NASA Technical Reports Server (NTRS)

Kalil, Michael

1987-01-01

The space station must unite the properties and behavior of individual and place, using proportions from both to make whole the understanding of ourselves at this moment in evolution. Harmonious proportions in any environment are similar to the acceptance and enjoyment of the harmony of many well-tuned musical instruments. A well-tuned or well-ordered environment tends to have invisible proportions. They produce order but do not intrude on the perception and cognitive mapping of the environment. Systems of proportion are not ends in themselves but are a means to select a series of spaces which relate one to another in dimensionally specific terms. These internal relationships create a whole when the forms are harmonious. This harmonic relationship is of intrinsic value for individuals to be physically and psychologically in balance with their universe.

Supramolecular effects as driving force of dipyrrin based functional materials engineering

NASA Astrophysics Data System (ADS)

Banakova, E.; Bobrov, A.; Kazak, A.; Marfin, Yu; Merkushev, D.; Molchanov, E.; Rumyantsev, E.; Shipalova, M.; Usoltsev, S.; Vodyanova, O.

2018-01-01

Dipyrrin based luminophores are of major interest in different areas of chemistry, material science and molecular biology. Vast variety of the structures with dipyrrin motif were synthesized and investigated up to date. Modern trend in the dipyrrin chemistry is the aimed functionalization of the ligand or complex structure allowing to gain the mechanism based on supramolecular interactions for controlling spectral and photophysical characteristics of compounds for tuning practically valuable properties for specific tasks. Presented paper summarize the results of our research group, working in the field of dipyrrin complexes with p-elements: synthesis, spectral characteristics evaluation and possibilities of practical application investigation. Discussion is focused on the opportunities of molecules preorganization for achieving the supramolecular interactions causing the tuning of fluorescence of the compounds in solutions, polymeric matrices and thin films.

Promoter library-based module combination (PLMC) technology for optimization of threonine biosynthesis in Corynebacterium glutamicum.

PubMed

Wei, Liang; Xu, Ning; Wang, Yiran; Zhou, Wei; Han, Guoqiang; Ma, Yanhe; Liu, Jun

2018-05-01

Due to the lack of efficient control elements and tools, the fine-tuning of gene expression in the multi-gene metabolic pathways is still a great challenge for engineering microbial cell factories, especially for the important industrial microorganism Corynebacterium glutamicum. In this study, the promoter library-based module combination (PLMC) technology was developed to efficiently optimize the expression of genes in C. glutamicum. A random promoter library was designed to contain the putative - 10 (NNTANANT) and - 35 (NNGNCN) consensus motifs, and refined through a three-step screening procedure to achieve numerous genetic control elements with different strength levels, including fluorescence-activated cell sorting (FACS) screening, agar plate screening, and 96-well plate screening. Multiple conventional strategies were employed for further precise characterizations of the promoter library, such as real-time quantitative PCR, sodium dodecyl sulfate polyacrylamide gel electrophoresis, FACS analysis, and the lacZ reporter system. These results suggested that the established promoter elements effectively regulated gene expression and showed varying strengths over a wide range. Subsequently, a multi-module combination technology was created based on the efficient promoter elements for combination and optimization of modules in the multi-gene pathways. Using this technology, the threonine biosynthesis pathway was reconstructed and optimized by predictable tuning expression of five modules in C. glutamicum. The threonine titer of the optimized strain was significantly improved to 12.8 g/L, an approximate 6.1-fold higher than that of the control strain. Overall, the PLMC technology presented in this study provides a rapid and effective method for combination and optimization of multi-gene pathways in C. glutamicum.

GeauxDock: Accelerating Structure-Based Virtual Screening with Heterogeneous Computing

PubMed Central

Fang, Ye; Ding, Yun; Feinstein, Wei P.; Koppelman, David M.; Moreno, Juana; Jarrell, Mark; Ramanujam, J.; Brylinski, Michal

2016-01-01

Computational modeling of drug binding to proteins is an integral component of direct drug design. Particularly, structure-based virtual screening is often used to perform large-scale modeling of putative associations between small organic molecules and their pharmacologically relevant protein targets. Because of a large number of drug candidates to be evaluated, an accurate and fast docking engine is a critical element of virtual screening. Consequently, highly optimized docking codes are of paramount importance for the effectiveness of virtual screening methods. In this communication, we describe the implementation, tuning and performance characteristics of GeauxDock, a recently developed molecular docking program. GeauxDock is built upon the Monte Carlo algorithm and features a novel scoring function combining physics-based energy terms with statistical and knowledge-based potentials. Developed specifically for heterogeneous computing platforms, the current version of GeauxDock can be deployed on modern, multi-core Central Processing Units (CPUs) as well as massively parallel accelerators, Intel Xeon Phi and NVIDIA Graphics Processing Unit (GPU). First, we carried out a thorough performance tuning of the high-level framework and the docking kernel to produce a fast serial code, which was then ported to shared-memory multi-core CPUs yielding a near-ideal scaling. Further, using Xeon Phi gives 1.9× performance improvement over a dual 10-core Xeon CPU, whereas the best GPU accelerator, GeForce GTX 980, achieves a speedup as high as 3.5×. On that account, GeauxDock can take advantage of modern heterogeneous architectures to considerably accelerate structure-based virtual screening applications. GeauxDock is open-sourced and publicly available at www.brylinski.org/geauxdock and https://figshare.com/articles/geauxdock_tar_gz/3205249. PMID:27420300

Smart Novel Semi-Active Tuned Mass Damper for Fixed-Bottom and Floating Offshore Wind (Paper)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez Tsouroukdissian, Arturo; Lackner, Mathew; Cross-Whiter, John

The intention of this paper is to present the results of a novel smart semi-active tuned mass damper (SA-TMD), which mitigates unwanted loads for both fixed-bottom and floating offshore wind systems. The paper will focus on the most challenging water depths for both fixed-bottom and floating systems. A close to 38m Monopile and 55m Tension Leg Platform (TLP) will be considered. A technical development and trade-off analysis will be presented comparing the new system with existing passive non-linear TMD (N-TMD) technology and semi-active. TheSATMD works passively and activates itself with low power source under unwanted dynamic loading in less thanmore » 60msec. It is composed of both variable stiffness and damping elements coupled to a central pendulum mass. The analysis has been done numerically in both FAST(NREL) and Orcaflex (Orcina), and integrated in the Wind Turbine system employing CAD/CAE. The results of this work will pave the way for experimental testing to complete the technology qualification process. The load reductions under extreme and fatigue cases reach up significant levels at tower base, consequently reducing LCOE for fixed-bottom to floating wind solutions. The nacelle acceleration is reduced substantially under severe random wind and sea states, reducing the risks of failure of electromechanical components and blades at the rotor nacelle assembly. The SA-TMD system isa new technology that has not been applied previously in wind solutions. Structural damping devices aim to increase offshore wind turbine system robustness and reliability, which eases multiple substructures installations and global stability.« less

GeauxDock: Accelerating Structure-Based Virtual Screening with Heterogeneous Computing.

PubMed

Fang, Ye; Ding, Yun; Feinstein, Wei P; Koppelman, David M; Moreno, Juana; Jarrell, Mark; Ramanujam, J; Brylinski, Michal

2016-01-01

Computational modeling of drug binding to proteins is an integral component of direct drug design. Particularly, structure-based virtual screening is often used to perform large-scale modeling of putative associations between small organic molecules and their pharmacologically relevant protein targets. Because of a large number of drug candidates to be evaluated, an accurate and fast docking engine is a critical element of virtual screening. Consequently, highly optimized docking codes are of paramount importance for the effectiveness of virtual screening methods. In this communication, we describe the implementation, tuning and performance characteristics of GeauxDock, a recently developed molecular docking program. GeauxDock is built upon the Monte Carlo algorithm and features a novel scoring function combining physics-based energy terms with statistical and knowledge-based potentials. Developed specifically for heterogeneous computing platforms, the current version of GeauxDock can be deployed on modern, multi-core Central Processing Units (CPUs) as well as massively parallel accelerators, Intel Xeon Phi and NVIDIA Graphics Processing Unit (GPU). First, we carried out a thorough performance tuning of the high-level framework and the docking kernel to produce a fast serial code, which was then ported to shared-memory multi-core CPUs yielding a near-ideal scaling. Further, using Xeon Phi gives 1.9× performance improvement over a dual 10-core Xeon CPU, whereas the best GPU accelerator, GeForce GTX 980, achieves a speedup as high as 3.5×. On that account, GeauxDock can take advantage of modern heterogeneous architectures to considerably accelerate structure-based virtual screening applications. GeauxDock is open-sourced and publicly available at www.brylinski.org/geauxdock and https://figshare.com/articles/geauxdock_tar_gz/3205249.

Electronic Tuning In The Hidden Order Compound URu2Si 2 Through Si → P substitution

NASA Astrophysics Data System (ADS)

Gallagher, Andrew

Crystalline materials that include 4f- and 5 f-electron elements frequently exhibit a variety of intriguing phenomena including spin and charge orderings, spin and valence fluctuations, heavy fermion behavior, breakdown of Fermi liquid behavior, and unconventional superconductivity. [5, 6, 7, 8, 9, 10, 11, 12, 13] Amongst such materials, the Kondo lattice system URu2Si2 stands out as being particularly unusual. [14, 15, 16] While at high temperature it exhibits behavior that is typical for an f-electron lattice immersed in a sea of conduction electrons, at T0 = 17:5 K there is a second order phase transition that is followed by unconventional superconductivity near Tc ≈ 1:5 K. [15] Despite three decades of work, the order parameter for the transition at T0 remains unknown and hence, it has been named "hidden order". There have been a multitude of experimental attempts to unravel hidden order, mainly through tuning of the electronic state via pressure, applied magnetic field, and chemical substitution. [17, 18] While these strategies reveal interesting phase diagrams, a longstanding challenge is that any such approach explores the phase space along an unknown vector: i.e., many different factors are affected. To address this issue, we developed a new organizational map for the U-based ThCr2Si2-type compounds that are related to URu2Si2 and thus guided, we explored a new chemical tuning axis: Si -> P. Our studies were enabled by the development of a new molten metal crystal growth method for URu2Si2 which produces high quality single crystals and allows us to introduce high vapor pressure elements, such as phosphorous. [19, 20] Si → P tuning reveals that while the high temperature Kondo lattice behavior is robust, the low temperature phenomena are remarkably sensitive to electronic tuning. [21, 22] In the URu2Si2-xPx phase diagram we find that while hidden order is monotonically suppressed and destroyed for x < 0.035, the superconducting strength evolves non-monotonically with a maximum near x = 0.01 and that superconductivity is destroyed near x ≈ 0.028. For 0.03 < x < 0.26 there is a region with Kondo coherence but no ordered state. Antiferromagnetism abruptly appears for x = 0.26. This phase diagram differs significantly from those produced by most other tuning strategies in URu2Si2, including applied pressure, and isoelectronic chemical substitution (i.e. Ru→Fe and Os), where hidden order and magnetism share a common phase boundary. [2, 23, 24] We discuss implications for understanding hidden order, its relationship to magnetism, and prospects for uncovering novel sibling electronic states.

Differential encoding of spatial information among retinal on cone bipolar cells

PubMed Central

Purgert, Robert J.

2015-01-01

The retina is the first stage of visual processing. It encodes elemental features of visual scenes. Distinct cone bipolar cells provide the substrate for this to occur. They encode visual information, such as color and luminance, a principle known as parallel processing. Few studies have directly examined whether different forms of spatial information are processed in parallel among cone bipolar cells. To address this issue, we examined the spatial information encoded by mouse ON cone bipolar cells, the subpopulation excited by increments in illumination. Two types of spatial processing were identified. We found that ON cone bipolar cells with axons ramifying in the central inner plexiform layer were tuned to preferentially encode small stimuli. By contrast, ON cone bipolar cells with axons ramifying in the proximal inner plexiform layer, nearest the ganglion cell layer, were tuned to encode both small and large stimuli. This dichotomy in spatial tuning is attributable to amacrine cells providing stronger inhibition to central ON cone bipolar cells compared with proximal ON cone bipolar cells. Furthermore, background illumination altered this difference in spatial tuning. It became less pronounced in bright light, as amacrine cell-driven inhibition became pervasive among all ON cone bipolar cells. These results suggest that differential amacrine cell input determined the distinct spatial encoding properties among ON cone bipolar cells. These findings enhance the known parallel processing capacity of the retina. PMID:26203104

Electro-mechanical control of an on-chip optical beam splitter containing an embedded quantum emitter.

PubMed

Bishop, Z K; Foster, A P; Royall, B; Bentham, C; Clarke, E; Skolnick, M S; Wilson, L R

2018-05-01

We demonstrate electro-mechanical control of an on-chip GaAs optical beam splitter containing a quantum dot single-photon source. The beam splitter consists of two nanobeam waveguides, which form a directional coupler (DC). The splitting ratio of the DC is controlled by varying the out-of-plane separation of the two waveguides using electromechanical actuation. We reversibly tune the beam splitter between an initial state, with emission into both output arms, and a final state with photons emitted into a single output arm. The device represents a compact and scalable tuning approach for use in III-V semiconductor integrated quantum optical circuits.

General self-tuning solutions and no-go theorem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Förste, Stefan; Kim, Jihn E.; Lee, Hyun Min, E-mail: forste@th.physik.uni-bonn.de, E-mail: jihnekim@gmail.com, E-mail: hyun.min.lee@kias.re.kr

2013-03-01

We consider brane world models with one extra dimension. In the bulk there is in addition to gravity a three form gauge potential or equivalently a scalar (by generalisation of electric magnetic duality). We find classical solutions for which the 4d effective cosmological constant is adjusted by choice of integration constants. No go theorems for such self-tuning mechanism are circumvented by unorthodox Lagrangians for the three form respectively the scalar. It is argued that the corresponding effective 4d theory always includes tachyonic Kaluza-Klein excitations or ghosts. Known no go theorems are extended to a general class of models with unorthodoxmore » Lagrangians.« less

Dual frequency, dual polarized, multi-layered microstrip slot and dipole array antenna

NASA Technical Reports Server (NTRS)

Tulintseff, Ann N. (Inventor)

1995-01-01

An antenna array system is disclosed which uses subarrays of slots and subarrays of dipoles on separate planes. The slots and dipoles respectively are interleaved, which is to say there is minimal overlap between them. Each subarray includes a microstrip transmission line and a plurality of elements extending perpendicular thereto. The dipoles form the transmission elements and the slots form the receive elements. The plane in which the slots are formed also forms a ground plane for the dipoles--hence the feed to the dipole is on the opposite side of this ground plane as the feed to the slots. HPAs are located adjacent the dipoles on one side of the substrate and LNAs are located adjacent the slots on the other side of the substrate. The dipoles and slots are tuned by setting different offsets between each element and the microstrip transmission line.

Predicting the properties of the lead alloys from DFT calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buimaga-Iarinca, L., E-mail: luiza.iarinca@itim-cj.ro; Calborean, A.

2015-12-23

We provide qualitative results for the physical properties of the lead alloys at atomic scale by using DFT calculations. Our approach is based on the two assumptions: (i) the geometric structure of lead atoms provides a matrix where the alloying elements can take their positions in the structure as substitutions and (ii) there is a small probability of a direct interaction between the alloying elements, thus the interactions of each alloying element may be approximated by the interactions to the lead matrix. DFT calculations are used to investigate the interaction between several types of impurities and the lead matrix formore » low concentrations of the alloying element. We report results such as the enthalpy of formation, charge transfer and mechanical stress induced by the impurities in the lead matrix; these results can be used as qualitative guide in tuning the physico-chemical properties of the lead alloys.« less

Ribo-attenuators: novel elements for reliable and modular riboswitch engineering.

PubMed

Folliard, Thomas; Mertins, Barbara; Steel, Harrison; Prescott, Thomas P; Newport, Thomas; Jones, Christopher W; Wadhams, George; Bayer, Travis; Armitage, Judith P; Papachristodoulou, Antonis; Rothschild, Lynn J

2017-07-04

Riboswitches are structural genetic regulatory elements that directly couple the sensing of small molecules to gene expression. They have considerable potential for applications throughout synthetic biology and bio-manufacturing as they are able to sense a wide range of small molecules and regulate gene expression in response. Despite over a decade of research they have yet to reach this considerable potential as they cannot yet be treated as modular components. This is due to several limitations including sensitivity to changes in genetic context, low tunability, and variability in performance. To overcome the associated difficulties with riboswitches, we have designed and introduced a novel genetic element called a ribo-attenuator in Bacteria. This genetic element allows for predictable tuning, insulation from contextual changes, and a reduction in expression variation. Ribo-attenuators allow riboswitches to be treated as truly modular and tunable components, thus increasing their reliability for a wide range of applications.

All-semiconductor high-speed akinetic swept-source for OCT

NASA Astrophysics Data System (ADS)

Minneman, Michael P.; Ensher, Jason; Crawford, Michael; Derickson, Dennis

2011-12-01

A novel swept-wavelength laser for optical coherence tomography (OCT) using a monolithic semiconductor device with no moving parts is presented. The laser is a Vernier-Tuned Distributed Bragg Reflector (VT-DBR) structure exhibiting a single longitudinal mode. All-electronic wavelength tuning is achieved at a 200 kHz sweep repetition rate, 20 mW output power, over 100 nm sweep width and coherence length longer than 40 mm. OCT point-spread functions with 45- 55 dB dynamic range are demonstrated; lasers at 1550 nm, and now 1310 nm, have been developed. Because the laser's long-term tuning stability allows for electronic sample trigger generation at equal k-space intervals (electronic k-clock), the laser does not need an external optical k-clock for measurement interferometer sampling. The non-resonant, allelectronic tuning allows for continuously adjustable sweep repetition rates from mHz to 100s of kHz. Repetition rate duty cycles are continuously adjustable from single-trigger sweeps to over 99% duty cycle. The source includes a monolithically integrated power leveling feature allowing flat or Gaussian power vs. wavelength profiles. Laser fabrication is based on reliable semiconductor wafer-scale processes, leading to low and rapidly decreasing cost of manufacture.

Opponent Coding of Sound Location (Azimuth) in Planum Temporale is Robust to Sound-Level Variations

PubMed Central

Derey, Kiki; Valente, Giancarlo; de Gelder, Beatrice; Formisano, Elia

2016-01-01

Coding of sound location in auditory cortex (AC) is only partially understood. Recent electrophysiological research suggests that neurons in mammalian auditory cortex are characterized by broad spatial tuning and a preference for the contralateral hemifield, that is, a nonuniform sampling of sound azimuth. Additionally, spatial selectivity decreases with increasing sound intensity. To accommodate these findings, it has been proposed that sound location is encoded by the integrated activity of neuronal populations with opposite hemifield tuning (“opponent channel model”). In this study, we investigated the validity of such a model in human AC with functional magnetic resonance imaging (fMRI) and a phase-encoding paradigm employing binaural stimuli recorded individually for each participant. In all subjects, we observed preferential fMRI responses to contralateral azimuth positions. Additionally, in most AC locations, spatial tuning was broad and not level invariant. We derived an opponent channel model of the fMRI responses by subtracting the activity of contralaterally tuned regions in bilateral planum temporale. This resulted in accurate decoding of sound azimuth location, which was unaffected by changes in sound level. Our data thus support opponent channel coding as a neural mechanism for representing acoustic azimuth in human AC. PMID:26545618

All-optical 1st- and 2nd-order differential equation solvers with large tuning ranges using Fabry-Pérot semiconductor optical amplifiers.

PubMed

Chen, Kaisheng; Hou, Jie; Huang, Zhuyang; Cao, Tong; Zhang, Jihua; Yu, Yuan; Zhang, Xinliang

2015-02-09

We experimentally demonstrate an all-optical temporal computation scheme for solving 1st- and 2nd-order linear ordinary differential equations (ODEs) with tunable constant coefficients by using Fabry-Pérot semiconductor optical amplifiers (FP-SOAs). By changing the injection currents of FP-SOAs, the constant coefficients of the differential equations are practically tuned. A quite large constant coefficient tunable range from 0.0026/ps to 0.085/ps is achieved for the 1st-order differential equation. Moreover, the constant coefficient p of the 2nd-order ODE solver can be continuously tuned from 0.0216/ps to 0.158/ps, correspondingly with the constant coefficient q varying from 0.0000494/ps(2) to 0.006205/ps(2). Additionally, a theoretical model that combining the carrier density rate equation of the semiconductor optical amplifier (SOA) with the transfer function of the Fabry-Pérot (FP) cavity is exploited to analyze the solving processes. For both 1st- and 2nd-order solvers, excellent agreements between the numerical simulations and the experimental results are obtained. The FP-SOAs based all-optical differential-equation solvers can be easily integrated with other optical components based on InP/InGaAsP materials, such as laser, modulator, photodetector and waveguide, which can motivate the realization of the complicated optical computing on a single integrated chip.

Multiple methods integration for structural mechanics analysis and design

NASA Technical Reports Server (NTRS)

Housner, J. M.; Aminpour, M. A.

1991-01-01

A new research area of multiple methods integration is proposed for joining diverse methods of structural mechanics analysis which interact with one another. Three categories of multiple methods are defined: those in which a physical interface are well defined; those in which a physical interface is not well-defined, but selected; and those in which the interface is a mathematical transformation. Two fundamental integration procedures are presented that can be extended to integrate various methods (e.g., finite elements, Rayleigh Ritz, Galerkin, and integral methods) with one another. Since the finite element method will likely be the major method to be integrated, its enhanced robustness under element distortion is also examined and a new robust shell element is demonstrated.

Nanoscale-driven crystal growth of hexaferrite heterostructures for magnetoelectric tuning of microwave semiconductor integrated devices.

PubMed

Hu, Bolin; Chen, Zhaohui; Su, Zhijuan; Wang, Xian; Daigle, Andrew; Andalib, Parisa; Wolf, Jason; McHenry, Michael E; Chen, Yajie; Harris, Vincent G

2014-11-25

A nanoscale-driven crystal growth of magnetic hexaferrites was successfully demonstrated at low growth temperatures (25-40% lower than the temperatures required often for crystal growth). This outcome exhibits thermodynamic processes of crystal growth, allowing ease in fabrication of advanced multifunctional materials. Most importantly, the crystal growth technique is considered theoretically and experimentally to be universal and suitable for the growth of a wide range of diverse crystals. In the present experiment, the conical spin structure of Co2Y ferrite crystals was found to give rise to an intrinsic magnetoelectric effect. Our experiment reveals a remarkable increase in the conical phase transition temperature by ∼150 K for Co2Y ferrite, compared to 5-10 K of Zn2Y ferrites recently reported. The high quality Co2Y ferrite crystals, having low microwave loss and magnetoelectricity, were successfully grown on a wide bandgap semiconductor GaN. The demonstration of the nanostructure materials-based "system on a wafer" architecture is a critical milestone to next generation microwave integrated systems. It is also practical that future microwave integrated systems and their magnetic performances could be tuned by an electric field because of the magnetoelectricity of hexaferrites.

Finite element area and line integral transforms for generalization of aperture function and geometry in Kirchhoff scalar diffraction theory

NASA Astrophysics Data System (ADS)

Kraus, Hal G.

1993-02-01

Two finite element-based methods for calculating Fresnel region and near-field region intensities resulting from diffraction of light by two-dimensional apertures are presented. The first is derived using the Kirchhoff area diffraction integral and the second is derived using a displaced vector potential to achieve a line integral transformation. The specific form of each of these formulations is presented for incident spherical waves and for Gaussian laser beams. The geometry of the two-dimensional diffracting aperture(s) is based on biquadratic isoparametric elements, which are used to define apertures of complex geometry. These elements are also used to build complex amplitude and phase functions across the aperture(s), which may be of continuous or discontinuous form. The finite element transform integrals are accurately and efficiently integrated numerically using Gaussian quadrature. The power of these methods is illustrated in several examples which include secondary obstructions, secondary spider supports, multiple mirror arrays, synthetic aperture arrays, apertures covered by screens, apodization, phase plates, and off-axis apertures. Typically, the finite element line integral transform results in significant gains in computational efficiency over the finite element Kirchhoff transform method, but is also subject to some loss in generality.

Six elements of integrated primary healthcare.

PubMed

Brown, Lynsey J; Oliver-Baxter, Jodie

2016-03-01

Integrated care has the potential to deliver efficiencies and improvements in patient experiences and health outcomes. Efforts towards integrated care, especially at the primary and community health levels, have increasingly been under focus, both nationally and internationally. In Australia, regional integration is a priority, and integration of care is a task for meso-level organisations such as Primary Health Networks (PHNs). This paper seeks to provide a list of elements and questions for consideration by organisations working across primary healthcare settings, looking to enact and improve the delivery of integrated care. Six elements that consistently emerged during the development of a series of rapid reviews on integrated primary healthcare in Australia are presented in this paper. The elements identified are context, governance and leadership, infrastructure, financing, engagement, and communication. They offer a starting point for reflection in the planning and practices of organisations in their drive for continuous improvements in integrated care.

Adaptive beam shaping by controlled thermal lensing in optical elements

NASA Astrophysics Data System (ADS)

Arain, Muzammil A.; Quetschke, Volker; Gleason, Joseph; Williams, Luke F.; Rakhmanov, Malik; Lee, Jinho; Cruz, Rachel J.; Mueller, Guido; Tanner, D. B.; Reitze, David. H.

2007-04-01

We describe an adaptive optical system for use as a tunable focusing element. The system provides adaptive beam shaping via controlled thermal lensing in the optical elements. The system is agile, remotely controllable, touch free, and vacuum compatible; it offers a wide dynamic range, aberration-free focal length tuning, and can provide both positive and negative lensing effects. Focusing is obtained through dynamic heating of an optical element by an external pump beam. The system is especially suitable for use in interferometric gravitational wave interferometers employing high laser power, allowing for in situ control of the laser modal properties and compensation for thermal lensing of the primary laser. Using CO2 laser heating of fused-silica substrates, we demonstrate a focal length variable from infinity to 4.0 m, with a slope of 0.082 diopter/W of absorbed heat. For on-axis operation, no higher-order modes are introduced by the adaptive optical element. Theoretical modeling of the induced optical path change and predicted thermal lens agrees well with measurement.

Adaptive beam shaping by controlled thermal lensing in optical elements.

PubMed

Arain, Muzammil A; Quetschke, Volker; Gleason, Joseph; Williams, Luke F; Rakhmanov, Malik; Lee, Jinho; Cruz, Rachel J; Mueller, Guido; Tanner, D B; Reitze, David H

2007-04-20

We describe an adaptive optical system for use as a tunable focusing element. The system provides adaptive beam shaping via controlled thermal lensing in the optical elements. The system is agile, remotely controllable, touch free, and vacuum compatible; it offers a wide dynamic range, aberration-free focal length tuning, and can provide both positive and negative lensing effects. Focusing is obtained through dynamic heating of an optical element by an external pump beam. The system is especially suitable for use in interferometric gravitational wave interferometers employing high laser power, allowing for in situ control of the laser modal properties and compensation for thermal lensing of the primary laser. Using CO(2) laser heating of fused-silica substrates, we demonstrate a focal length variable from infinity to 4.0 m, with a slope of 0.082 diopter/W of absorbed heat. For on-axis operation, no higher-order modes are introduced by the adaptive optical element. Theoretical modeling of the induced optical path change and predicted thermal lens agrees well with measurement.

Digital lock-in detection of site-specific magnetism in magnetic materials

DOEpatents

Haskel, Daniel [Naperville, IL; Lang, Jonathan C [Naperville, IL; Srajer, George [Oak Park, IL

2008-07-22

The polarization and diffraction characteristics of x-rays incident upon a magnetic material are manipulated to provide a desired magnetic sensitivity in the material. The contrast in diffracted intensity of opposite helicities of circularly polarized x-rays is measured to permit separation of magnetic signals by element type and by atomic environment. This allows for the direct probing of magnetic signals from elements of the same species in nonequivalent atomic environments to better understand the behavior and characteristics of permanent magnetic materials. By using known crystallographic information together with manipulation of the polarization of x-rays having energies tuned near element-specific electronic excitations and by detecting and comparing the incident and diffracted photons at the same frequency, more accurate magnetic measurements can be made over shorter observation periods.

Tuning the properties of conjugated polyelectrolytes and application in a biosensor platform

DOEpatents

Chen, Liaohai

2004-05-18

The present invention provides a method of detecting a biological agent including contacting a sample with a sensor including a polymer system capable of having an alterable measurable property from the group of luminescence, anisotropy, redox potential and uv/vis absorption, the polymer system including an ionic conjugated polymer and an electronically inert polyelectrolyte having a biological agent recognition element bound thereto, the electronically inert polyelectrolyte adapted for undergoing a conformational structural change upon exposure to a biological agent having affinity for binding to the recognition element bound to the electronically inert polyelectrolyte, and, detecting the detectable change in the alterable measurable property. A chemical moiety being the reaction product of (i) a polyelectrolyte monomer and (ii) a biological agent recognition element-substituted polyelectrolyte monomer is also provided.

Weak Galerkin finite element methods for Darcy flow: Anisotropy and heterogeneity

NASA Astrophysics Data System (ADS)

Lin, Guang; Liu, Jiangguo; Mu, Lin; Ye, Xiu

2014-11-01

This paper presents a family of weak Galerkin finite element methods (WGFEMs) for Darcy flow computation. The WGFEMs are new numerical methods that rely on the novel concept of discrete weak gradients. The WGFEMs solve for pressure unknowns both in element interiors and on the mesh skeleton. The numerical velocity is then obtained from the discrete weak gradient of the numerical pressure. The new methods are quite different than many existing numerical methods in that they are locally conservative by design, the resulting discrete linear systems are symmetric and positive-definite, and there is no need for tuning problem-dependent penalty factors. We test the WGFEMs on benchmark problems to demonstrate the strong potential of these new methods in handling strong anisotropy and heterogeneity in Darcy flow.

A Novel Polygonal Finite Element Method: Virtual Node Method

NASA Astrophysics Data System (ADS)

Tang, X. H.; Zheng, C.; Zhang, J. H.

2010-05-01

Polygonal finite element method (PFEM), which can construct shape functions on polygonal elements, provides greater flexibility in mesh generation. However, the non-polynomial form of traditional PFEM, such as Wachspress method and Mean Value method, leads to inexact numerical integration. Since the integration technique for non-polynomial functions is immature. To overcome this shortcoming, a great number of integration points have to be used to obtain sufficiently exact results, which increases computational cost. In this paper, a novel polygonal finite element method is proposed and called as virtual node method (VNM). The features of present method can be list as: (1) It is a PFEM with polynomial form. Thereby, Hammer integral and Gauss integral can be naturally used to obtain exact numerical integration; (2) Shape functions of VNM satisfy all the requirements of finite element method. To test the performance of VNM, intensive numerical tests are carried out. It found that, in standard patch test, VNM can achieve significantly better results than Wachspress method and Mean Value method. Moreover, it is observed that VNM can achieve better results than triangular 3-node elements in the accuracy test.

Performance tuning of N-body codes on modern microprocessors: I. Direct integration with a hermite scheme on x86_64 architecture

NASA Astrophysics Data System (ADS)

Nitadori, Keigo; Makino, Junichiro; Hut, Piet

2006-12-01

The main performance bottleneck of gravitational N-body codes is the force calculation between two particles. We have succeeded in speeding up this pair-wise force calculation by factors between 2 and 10, depending on the code and the processor on which the code is run. These speed-ups were obtained by writing highly fine-tuned code for x86_64 microprocessors. Any existing N-body code, running on these chips, can easily incorporate our assembly code programs. In the current paper, we present an outline of our overall approach, which we illustrate with one specific example: the use of a Hermite scheme for a direct N2 type integration on a single 2.0 GHz Athlon 64 processor, for which we obtain an effective performance of 4.05 Gflops, for double-precision accuracy. In subsequent papers, we will discuss other variations, including the combinations of N log N codes, single-precision implementations, and performance on other microprocessors.

Wave propagation in elastic and damped structures with stabilized negative-stiffness components

NASA Astrophysics Data System (ADS)

Drugan, W. J.

2017-09-01

Effects on wave propagation achievable by introduction of a negative-stiffness component are investigated via perhaps the simplest discrete repeating element that can remain stable in the component's presence. When the system is elastic, appropriate tuning of the stabilized component's negative stiffness introduces a no-pass zone theoretically extending from zero to an arbitrarily high frequency, tunable by a mass ratio adjustment. When the negative-stiffness component is tuned to the system's stability limit and a mass ratio is sufficiently small, the system restricts propagation to waves of approximately a single arbitrary frequency, adjustable by tuning the stiffness ratio of the positive-stiffness components. The elastic system's general solutions are closed-form and transparent. When damping is added, the general solutions are still closed-form, but so complex that they do not clearly display how the negative stiffness component affects the system's response and how it should best be tuned to achieve desired effects. Approximate solutions having these features are obtained via four perturbation analyses: one for long wavelengths; one for small damping; and two for small mass ratios. The long-wavelengths solution shows that appropriate tuning of the negative-stiffness component can prevent propagation of long-wavelength waves. The small damping solution shows that the zero-damping low-frequency no-pass zone remains, while waves that do propagate are highly damped when a mass ratio is made small. Finally, very interesting effects are achievable at the full system's stability limit. For small mass ratios, the wavelength range of waves prohibited from propagation can be adjusted, from all to none, by tuning the system's damping: When one mass ratio is small, all waves with wavelengths larger than an arbitrary damping-adjusted value can be prohibited from propagation, while when the inverse of this mass ratio is small, all waves with wavelengths outside an arbitrary single adjustable value or range of values can be prohibited from propagation. All of the approximate solutions' analytically-transparent predictions are confirmed by the exact solution. The conclusions are that a stabilized tuned negative-stiffness component greatly enhances control of wave propagation in a purely elastic system, and when adjustable damping is added, even further control is facilitated.

AUTOMATIC FREQUENCY CONTROL SYSTEM

DOEpatents

Hansen, C.F.; Salisbury, J.D.

1961-01-10

A control is described for automatically matching the frequency of a resonant cavity to that of a driving oscillator. The driving oscillator is disconnected from the cavity and a secondary oscillator is actuated in which the cavity is the frequency determining element. A low frequency is mixed with the output of the driving oscillator and the resultant lower and upper sidebands are separately derived. The frequencies of the sidebands are compared with the secondary oscillator frequency. deriving a servo control signal to adjust a tuning element in the cavity and matching the cavity frequency to that of the driving oscillator. The driving oscillator may then be connected to the cavity.

Transposable Elements Re-Wire and Fine-Tune the Transcriptome

PubMed Central

Cowley, Michael; Oakey, Rebecca J.

2013-01-01

What good are transposable elements (TEs)? Although their activity can be harmful to host genomes and can cause disease, they nevertheless represent an important source of genetic variation that has helped shape genomes. In this review, we examine the impact of TEs, collectively referred to as the mobilome, on the transcriptome. We explore how TEs—particularly retrotransposons—contribute to transcript diversity and consider their potential significance as a source of small RNAs that regulate host gene transcription. We also discuss a critical role for the mobilome in engineering transcriptional networks, permitting coordinated gene expression, and facilitating the evolution of novel physiological processes. PMID:23358118

Split-Waveguide Mounts For Submillimeter-Wave Multipliers And Harmonic Mixers

NASA Technical Reports Server (NTRS)

Raisanen, Antti; Choudhury, Debabani; Dengler, Robert J.; Oswald, John E.; Siegel, Peter H.

1996-01-01

Novel variation of split-waveguide mount for millimeter-and submillimeter-wavelength frequency multipliers and harmonic mixers developed. Designed to offer wide range of available matching impedances, while maintaining relatively simple fabrication sequence. Wide tuning range achieved with separate series and parallel elements, consisting of two pairs of noncontacting sliding backshorts, at fundamental and harmonic frequencies. Advantages include ease of fabrication, reliability, and tunability.

The NuMI neutrino beam

NASA Astrophysics Data System (ADS)

Adamson, P.; Anderson, K.; Andrews, M.; Andrews, R.; Anghel, I.; Augustine, D.; Aurisano, A.; Avvakumov, S.; Ayres, D. S.; Baller, B.; Barish, B.; Barr, G.; Barrett, W. L.; Bernstein, R. H.; Biggs, J.; Bishai, M.; Blake, A.; Bocean, V.; Bock, G. J.; Boehnlein, D. J.; Bogert, D.; Bourkland, K.; Cao, S. V.; Castromonte, C. M.; Childress, S.; Choudhary, B. C.; Coelho, J. A. B.; Cobb, J. H.; Corwin, L.; Crane, D.; Cravens, J. P.; Cronin-Hennessy, D.; Ducar, R. J.; De Jong, J. K.; Devan, A. V.; Devenish, N. E.; Diwan, M. V.; Erwin, A. R.; Escobar, C. O.; Evans, J. J.; Falk, E.; Feldman, G. J.; Fields, T. H.; Ford, R.; Frohne, M. V.; Gallagher, H. R.; Garkusha, V.; Gomes, R. A.; Goodman, M. C.; Gouffon, P.; Graf, N.; Gran, R.; Grossman, N.; Grzelak, K.; Habig, A.; Hahn, S. R.; Harding, D.; Harris, D.; Harris, P. G.; Hartnell, J.; Hatcher, R.; Hays, S.; Heller, K.; Holin, A.; Huang, J.; Hylen, J.; Ibrahim, A.; Indurthy, D.; Irwin, G. M.; Isvan, Z.; Jaffe, D. E.; James, C.; Jensen, D.; Johnstone, J.; Kafka, T.; Kasahara, S. M. S.; Koizumi, G.; Kopp, S.; Kordosky, M.; Kreymer, A.; Lang, K.; Laughton, C.; Lefeuvre, G.; Ling, J.; Litchfield, P. J.; Loiacono, L.; Lucas, P.; Mann, W. A.; Marchionni, A.; Marshak, M. L.; Mayer, N.; McGivern, C.; Medeiros, M. M.; Mehdiyev, R.; Meier, J. R.; Messier, M. D.; Michael, D. G.; Milburn, R. H.; Miller, J. L.; Miller, W. H.; Mishra, S. R.; Moed Sher, S.; Moore, C. D.; Morfín, J.; Mualem, L.; Mufson, S.; Murgia, S.; Murtagh, M.; Musser, J.; Naples, D.; Nelson, J. K.; Newman, H. B.; Nichol, R. J.; Nowak, J. A.; O`Connor, J.; Oliver, W. P.; Olsen, M.; Orchanian, M.; Osprey, S.; Pahlka, R. B.; Paley, J.; Para, A.; Patterson, R. B.; Patzak, T.; Pavlović, Ž.; Pawloski, G.; Perch, A.; Peterson, E. A.; Petyt, D. A.; Pfützner, M. M.; Phan-Budd, S.; Plunkett, R. K.; Poonthottathil, N.; Prieto, P.; Pushka, D.; Qiu, X.; Radovic, A.; Rameika, R. A.; Ratchford, J.; Rebel, B.; Reilly, R.; Rosenfeld, C.; Rubin, H. A.; Ruddick, K.; Sanchez, M. C.; Saoulidou, N.; Sauer, L.; Schneps, J.; Schoo, D.; Schreckenberger, A.; Schreiner, P.; Shanahan, P.; Sharma, R.; Smart, W.; Smith, C.; Sousa, A.; Stefanik, A.; Tagg, N.; Talaga, R. L.; Tassotto, G.; Thomas, J.; Thompson, J.; Thomson, M. A.; Tian, X.; Timmons, A.; Tinsley, D.; Tognini, S. C.; Toner, R.; Torretta, D.; Trostin, I.; Tzanakos, G.; Urheim, J.; Vahle, P.; Vaziri, K.; Villegas, E.; Viren, B.; Vogel, G.; Webber, R. C.; Weber, A.; Webb, R. C.; Wehmann, A.; White, C.; Whitehead, L.; Whitehead, L. H.; Wojcicki, S. G.; Wong-Squires, M. L.; Yang, T.; Yumiceva, F. X.; Zarucheisky, V.; Zwaska, R.

2016-01-01

This paper describes the hardware and operations of the Neutrinos at the Main Injector (NuMI) beam at Fermilab. It elaborates on the design considerations for the beam as a whole and for individual elements. The most important design details of individual components are described. Beam monitoring systems and procedures, including the tuning and alignment of the beam and NuMI long-term performance, are also discussed.

The Great Tunes of the Hough: Music and Song in Alan Garner's "The Stone Book Quartet "

ERIC Educational Resources Information Center

Godek, Sarah

2004-01-01

Although song and music are often elements in children's books, little critical attention has gone into examining their literary uses. Alan Garner's "The Stone Book Quartet" is an example of four texts for children in which music plays a vital role. The several snatches of traditional songs found throughout the quartet bring to life the culture of…

Design and Analysis of Broad-Band Fixed-Tuned Submillimeter-Waveguide Multipliers using MMIC Style Circuit Topology

NASA Technical Reports Server (NTRS)

Bruston, J.; Kim, M.; Martin, S. C.; Mehdi, I.; Smith, R. P.; Siegel, P. H.

1996-01-01

The design and analysis of varactor diode doubler, quadrupler and cascaded doubler circuits for 320 and 640 GHz have been completed. A new approach has been employed to produce a tunerless waveguide mount with a very flexible, frequency scaleable, MMIC style multiplier circuit. The concept, design, predicted performance and measurements on some of the constituent mount elements are presented.

S/He Who Pays the Piper Calls the Tune? Professionalism, Developmentalism, and the Paucity of In-Service Education within the Research Profession

ERIC Educational Resources Information Center

Evans, Linda

2009-01-01

This paper focuses on the research-related, in-service professional development of social science academic researchers. It identifies as a gap in provision the paucity of provision of career-long training in the "creative" elements of research practice--specifically the methodological skills that have the potential to enhance individuals' research…

Forced vibration analysis of rotating cyclic structures in NASTRAN

NASA Technical Reports Server (NTRS)

Elchuri, V.; Gallo, A. M.; Skalski, S. C.

1981-01-01

A new capability was added to the general purpose finite element program NASTRAN Level 17.7 to conduct forced vibration analysis of tuned cyclic structures rotating about their axis of symmetry. The effects of Coriolis and centripetal accelerations together with those due to linear acceleration of the axis of rotation were included. The theoretical, user's, programmer's and demonstration manuals for this new capability are presented.

Extended depth of field integral imaging using multi-focus fusion

NASA Astrophysics Data System (ADS)

Piao, Yongri; Zhang, Miao; Wang, Xiaohui; Li, Peihua

2018-03-01

In this paper, we propose a new method for depth of field extension in integral imaging by realizing the image fusion method on the multi-focus elemental images. In the proposed method, a camera is translated on a 2D grid to take multi-focus elemental images by sweeping the focus plane across the scene. Simply applying an image fusion method on the elemental images holding rich parallax information does not work effectively because registration accuracy of images is the prerequisite for image fusion. To solve this problem an elemental image generalization method is proposed. The aim of this generalization process is to geometrically align the objects in all elemental images so that the correct regions of multi-focus elemental images can be exacted. The all-in focus elemental images are then generated by fusing the generalized elemental images using the block based fusion method. The experimental results demonstrate that the depth of field of synthetic aperture integral imaging system has been extended by realizing the generation method combined with the image fusion on multi-focus elemental images in synthetic aperture integral imaging system.

Improved finite element methodology for integrated thermal structural analysis

NASA Technical Reports Server (NTRS)

Dechaumphai, P.; Thornton, E. A.

1982-01-01

An integrated thermal-structural finite element approach for efficient coupling of thermal and structural analysis is presented. New thermal finite elements which yield exact nodal and element temperatures for one dimensional linear steady state heat transfer problems are developed. A nodeless variable formulation is used to establish improved thermal finite elements for one dimensional nonlinear transient and two dimensional linear transient heat transfer problems. The thermal finite elements provide detailed temperature distributions without using additional element nodes and permit a common discretization with lower order congruent structural finite elements. The accuracy of the integrated approach is evaluated by comparisons with analytical solutions and conventional finite element thermal structural analyses for a number of academic and more realistic problems. Results indicate that the approach provides a significant improvement in the accuracy and efficiency of thermal stress analysis for structures with complex temperature distributions.

Improved accuracy for finite element structural analysis via an integrated force method

NASA Technical Reports Server (NTRS)

Patnaik, S. N.; Hopkins, D. A.; Aiello, R. A.; Berke, L.

1992-01-01

A comparative study was carried out to determine the accuracy of finite element analyses based on the stiffness method, a mixed method, and the new integrated force and dual integrated force methods. The numerical results were obtained with the following software: MSC/NASTRAN and ASKA for the stiffness method; an MHOST implementation method for the mixed method; and GIFT for the integrated force methods. The results indicate that on an overall basis, the stiffness and mixed methods present some limitations. The stiffness method generally requires a large number of elements in the model to achieve acceptable accuracy. The MHOST method tends to achieve a higher degree of accuracy for course models than does the stiffness method implemented by MSC/NASTRAN and ASKA. The two integrated force methods, which bestow simultaneous emphasis on stress equilibrium and strain compatibility, yield accurate solutions with fewer elements in a model. The full potential of these new integrated force methods remains largely unexploited, and they hold the promise of spawning new finite element structural analysis tools.

Art for the Brain's Sake.

ERIC Educational Resources Information Center

Sylwester, Robert

1998-01-01

From fine-tuning muscular systems to integrating emotion and logic, the arts have important biological value. Motion and emotion are central to the arts and life itself. It is counterproductive to promote high performance standards while displacing skill development with computer technologies and reducing arts programs that move students from…

A computer program for anisotropic shallow-shell finite elements using symbolic integration

NASA Technical Reports Server (NTRS)

Andersen, C. M.; Bowen, J. T.

1976-01-01

A FORTRAN computer program for anisotropic shallow-shell finite elements with variable curvature is described. A listing of the program is presented together with printed output for a sample case. Computation times and central memory requirements are given for several different elements. The program is based on a stiffness (displacement) finite-element model in which the fundamental unknowns consist of both the displacement and the rotation components of the reference surface of the shell. Two triangular and four quadrilateral elements are implemented in the program. The triangular elements have 6 or 10 nodes, and the quadrilateral elements have 4 or 8 nodes. Two of the quadrilateral elements have internal degrees of freedom associated with displacement modes which vanish along the edges of the elements (bubble modes). The triangular elements and the remaining two quadrilateral elements do not have bubble modes. The output from the program consists of arrays corresponding to the stiffness, the geometric stiffness, the consistent mass, and the consistent load matrices for individual elements. The integrals required for the generation of these arrays are evaluated by using symbolic (or analytic) integration in conjunction with certain group-theoretic techniques. The analytic expressions for the integrals are exact and were developed using the symbolic and algebraic manipulation language.

Heading Tuning in Macaque Area V6.

PubMed

Fan, Reuben H; Liu, Sheng; DeAngelis, Gregory C; Angelaki, Dora E

2015-12-16

Cortical areas, such as the dorsal subdivision of the medial superior temporal area (MSTd) and the ventral intraparietal area (VIP), have been shown to integrate visual and vestibular self-motion signals. Area V6 is interconnected with areas MSTd and VIP, allowing for the possibility that V6 also integrates visual and vestibular self-motion cues. An alternative hypothesis in the literature is that V6 does not use these sensory signals to compute heading but instead discounts self-motion signals to represent object motion. However, the responses of V6 neurons to visual and vestibular self-motion cues have never been studied, thus leaving the functional roles of V6 unclear. We used a virtual reality system to examine the 3D heading tuning of macaque V6 neurons in response to optic flow and inertial motion stimuli. We found that the majority of V6 neurons are selective for heading defined by optic flow. However, unlike areas MSTd and VIP, V6 neurons are almost universally unresponsive to inertial motion in the absence of optic flow. We also explored the spatial reference frames of heading signals in V6 by measuring heading tuning for different eye positions, and we found that the visual heading tuning of most V6 cells was eye-centered. Similar to areas MSTd and VIP, the population of V6 neurons was best able to discriminate small variations in heading around forward and backward headings. Our findings support the idea that V6 is involved primarily in processing visual motion signals and does not appear to play a role in visual-vestibular integration for self-motion perception. To understand how we successfully navigate our world, it is important to understand which parts of the brain process cues used to perceive our direction of self-motion (i.e., heading). Cortical area V6 has been implicated in heading computations based on human neuroimaging data, but direct measurements of heading selectivity in individual V6 neurons have been lacking. We provide the first demonstration that V6 neurons carry 3D visual heading signals, which are represented in an eye-centered reference frame. In contrast, we found almost no evidence for vestibular heading signals in V6, indicating that V6 is unlikely to contribute to multisensory integration of heading signals, unlike other cortical areas. These findings provide important constraints on the roles of V6 in self-motion perception. Copyright © 2015 the authors 0270-6474/15/3516303-12$15.00/0.

PMF5.0 vs. CMB8.2: An inter-comparison study based on the new European SPECIEUROPE database

NASA Astrophysics Data System (ADS)

Bove, Maria Chiara; Massabò, Dario; Prati, Paolo

2018-03-01

Receptor Models are tools widely adopted in source apportionment studies. We describe here an experiment in which we integrated two different approaches, i.e. Positive Matrix Factorization (PMF) and Chemical Mass Balance (CMB) to apportion a set of PM10 (i.e. Particulate Matter with aerodynamic diameter lower than 10 μm) concentration values. The study was performed in the city of Genoa (Italy): a sampling campaign was carried out collecting daily PM10 samples for about two months in an urban background site. PM10 was collected on Quartz fiber filters by a low-volume sampler. A quite complete speciation of PM samples was obtained via Energy Dispersive-X Ray Fluorescence (ED-XRF, for elements), Ionic Chromatography (IC, for major ions and levoglucosan), thermo-optical Analysis (TOT, for organic and elemental carbon). The chemical analyses provided the input database for source apportionment by both PMF and CMB. Source profiles were directly calculated from the input data by PMF while in the CMB runs they were first calculated by averaging the profiles of similar sources collected in the European database SPECIEUROPE. Differences between the two receptor models emerged in particular with PM10 sources linked to very local processes. For this reason, PMF source profiles were adopted in refined CMB runs thus testing a new hybrid approach. Finally, PMF and the "tuned" CMB showed a better agreement even if some discrepancies could not completely been resolved. In this work, we compared the results coming from the last available PMF and CMB versions applied on a set of PM10 samples. Input profiles used in CMB analysis were obtained by averaging the profiles of the new European SPECIEUROPE database. The main differences between PMF and CMB results were linked to very local processes: we obtained the best solution by integrating the two different approaches with the implementation of some output PMF profiles to CMB runs.

Neural Network-Based Self-Tuning PID Control for Underwater Vehicles

PubMed Central

Hernández-Alvarado, Rodrigo; García-Valdovinos, Luis Govinda; Salgado-Jiménez, Tomás; Gómez-Espinosa, Alfonso; Fonseca-Navarro, Fernando

2016-01-01

For decades, PID (Proportional + Integral + Derivative)-like controllers have been successfully used in academia and industry for many kinds of plants. This is thanks to its simplicity and suitable performance in linear or linearized plants, and under certain conditions, in nonlinear ones. A number of PID controller gains tuning approaches have been proposed in the literature in the last decades; most of them off-line techniques. However, in those cases wherein plants are subject to continuous parametric changes or external disturbances, online gains tuning is a desirable choice. This is the case of modular underwater ROVs (Remotely Operated Vehicles) where parameters (weight, buoyancy, added mass, among others) change according to the tool it is fitted with. In practice, some amount of time is dedicated to tune the PID gains of a ROV. Once the best set of gains has been achieved the ROV is ready to work. However, when the vehicle changes its tool or it is subject to ocean currents, its performance deteriorates since the fixed set of gains is no longer valid for the new conditions. Thus, an online PID gains tuning algorithm should be implemented to overcome this problem. In this paper, an auto-tune PID-like controller based on Neural Networks (NN) is proposed. The NN plays the role of automatically estimating the suitable set of PID gains that achieves stability of the system. The NN adjusts online the controller gains that attain the smaller position tracking error. Simulation results are given considering an underactuated 6 DOF (degrees of freedom) underwater ROV. Real time experiments on an underactuated mini ROV are conducted to show the effectiveness of the proposed scheme. PMID:27608018

Neural Network-Based Self-Tuning PID Control for Underwater Vehicles.

PubMed

Hernández-Alvarado, Rodrigo; García-Valdovinos, Luis Govinda; Salgado-Jiménez, Tomás; Gómez-Espinosa, Alfonso; Fonseca-Navarro, Fernando

2016-09-05

For decades, PID (Proportional + Integral + Derivative)-like controllers have been successfully used in academia and industry for many kinds of plants. This is thanks to its simplicity and suitable performance in linear or linearized plants, and under certain conditions, in nonlinear ones. A number of PID controller gains tuning approaches have been proposed in the literature in the last decades; most of them off-line techniques. However, in those cases wherein plants are subject to continuous parametric changes or external disturbances, online gains tuning is a desirable choice. This is the case of modular underwater ROVs (Remotely Operated Vehicles) where parameters (weight, buoyancy, added mass, among others) change according to the tool it is fitted with. In practice, some amount of time is dedicated to tune the PID gains of a ROV. Once the best set of gains has been achieved the ROV is ready to work. However, when the vehicle changes its tool or it is subject to ocean currents, its performance deteriorates since the fixed set of gains is no longer valid for the new conditions. Thus, an online PID gains tuning algorithm should be implemented to overcome this problem. In this paper, an auto-tune PID-like controller based on Neural Networks (NN) is proposed. The NN plays the role of automatically estimating the suitable set of PID gains that achieves stability of the system. The NN adjusts online the controller gains that attain the smaller position tracking error. Simulation results are given considering an underactuated 6 DOF (degrees of freedom) underwater ROV. Real time experiments on an underactuated mini ROV are conducted to show the effectiveness of the proposed scheme.

Widely bandwidth-tunable silicon filter with an unlimited free-spectral range.

PubMed

St-Yves, Jonathan; Bahrami, Hadi; Jean, Philippe; LaRochelle, Sophie; Shi, Wei

2015-12-01

Next-generation high-capacity optical networks require flexible allocation of spectrum resources, for which low-cost optical filters with an ultra-wide bandwidth tunability beyond 100 GHz are desired. We demonstrate an integrated band-pass filter with the bandwidth continuously tuned across 670 GHz (117-788 GHz) which, to the best of our knowledge, is the widest tuning span ever demonstrated on a silicon chip. The filter also features simultaneous wavelength tuning and an unlimited free spectral range. We measured an out-of-band contrast of up to 55 dB, low in-band ripples of less than 0.3 dB, and in-band group delay variation of less than 8 ps. This result was achieved using cascaded Bragg-grating-assisted contra-directional couplers and micro-heaters on the 220 nm silicon-on-insulator platform with a very compact footprint of less than 7000  μm2. Another design with the bandwidth continuously tunable from 50 GHz to 1 THz is also presented.

Actively addressed single pixel full-colour plasmonic display

PubMed Central

Franklin, Daniel; Frank, Russell; Wu, Shin-Tson; Chanda, Debashis

2017-01-01

Dynamic, colour-changing surfaces have many applications including displays, wearables and active camouflage. Plasmonic nanostructures can fill this role by having the advantages of ultra-small pixels, high reflectivity and post-fabrication tuning through control of the surrounding media. However, previous reports of post-fabrication tuning have yet to cover a full red-green-blue (RGB) colour basis set with a single nanostructure of singular dimensions. Here, we report a method which greatly advances this tuning and demonstrates a liquid crystal-plasmonic system that covers the full RGB colour basis set, only as a function of voltage. This is accomplished through a surface morphology-induced, polarization-dependent plasmonic resonance and a combination of bulk and surface liquid crystal effects that manifest at different voltages. We further demonstrate the system's compatibility with existing LCD technology by integrating it with a commercially available thin-film-transistor array. The imprinted surface interfaces readily with computers to display images as well as video. PMID:28488671

Orientation Tuning in the Visual Cortex of 3-Month-old Human Infants

PubMed Central

Baker, Thomas J.; Norcia, Anthony M.; Candy, T. Rowan

2016-01-01

Sensitivity to orientation is critical for making a whole and complete picture of the world. We measured the orientation tuning of mechanisms inthe visual cortex of typically developing 3-month-olds and adults using a nonlinear analysis of the two-input steady-state visually evoked potential (VEP). Two gratings, one a fixed test and the other a variable orientation masker were tagged with distinct temporal frequencies and the corresponding evoked responses were measured at the harmonics of the test and masker frequencies and at a frequency equal to the sum of the two stimulus frequencies. The magnitude of the sum frequency component depended strongly on the relative orientation of the test and masker in both infants and adults. The VEP tuning bandwidths of the 3-month-olds measured at the sum frequency were similar to those of adults, suggesting that behavioral immaturities in functions such as orientation discrimination and contour integration may result from other immaturities in long-range lateral projections or feedback mechanisms. PMID:21236289

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Xuenan; Zhang Yundong; Tian He

We propose to employ the storage of light in a dynamically tuned add-drop resonator to realize an optical gyroscope of ultrahigh sensitivity and compact size. Taking the impact of the linewidth of incident light on the sensitivity into account, we investigate the effect of rotation on the propagation of a partially coherent light field in this dynamically tuned slow-light structure. It is demonstrated that the fundamental trade-off between the rotation-detection sensitivity and the linewidth will be overcome and the sensitivity-linewidth product will be enhanced by two orders of magnitude in comparison to that of the corresponding static slow-light structure. Furthermore,more » the optical gyroscope employing the storage of light in the dynamically tuned add-drop resonator can acquire ultrahigh sensitivity by extremely short fiber length without a high-performance laser source of narrow linewidth and a complex laser frequency stabilization system. Thus the proposal in this paper provides a promising and feasible scheme to realize highly sensitive and compact integrated optical gyroscopes by slow-light structures.« less

Learning and tuning fuzzy logic controllers through reinforcements

NASA Technical Reports Server (NTRS)

Berenji, Hamid R.; Khedkar, Pratap

1992-01-01

A new method for learning and tuning a fuzzy logic controller based on reinforcements from a dynamic system is presented. In particular, our Generalized Approximate Reasoning-based Intelligent Control (GARIC) architecture: (1) learns and tunes a fuzzy logic controller even when only weak reinforcements, such as a binary failure signal, is available; (2) introduces a new conjunction operator in computing the rule strengths of fuzzy control rules; (3) introduces a new localized mean of maximum (LMOM) method in combining the conclusions of several firing control rules; and (4) learns to produce real-valued control actions. Learning is achieved by integrating fuzzy inference into a feedforward network, which can then adaptively improve performance by using gradient descent methods. We extend the AHC algorithm of Barto, Sutton, and Anderson to include the prior control knowledge of human operators. The GARIC architecture is applied to a cart-pole balancing system and has demonstrated significant improvements in terms of the speed of learning and robustness to changes in the dynamic system's parameters over previous schemes for cart-pole balancing.

Adaptive Helmholtz resonators and passive vibration absorbers for cylinder interior noise control

NASA Astrophysics Data System (ADS)

Estève, Simon J.; Johnson, Marty E.

2005-12-01

This paper presents an adaptive-passive solution to control the broadband sound transmission into rocket payload fairings. The treatment is composed of passive distributed vibration absorbers (DVAs) and adaptive Helmholtz resonators (HR). Both the frequency domain and time-domain model of a simply supported cylinder excited by an external plane wave are developed. To tune vibration absorbers to tonal excitation, a tuning strategy, based on the phase information between the velocity of the absorber mass and the velocity of the host structure is used here in a new fashion to tune resonators to peaks in the broadband acoustic spectrum of a cavity. This tuning law, called the dot-product method, only uses two microphone signals local to each HR, which allows the adaptive Helmholtz resonator (AHR) to be manufactured as an autonomous device with power supply, sensor, actuator and controller integrated. Numerical simulations corresponding to a 2.8 m long 2.5 m diameter composite cylinder prototype demonstrate that, as long as the structure modes, which strongly couple to the acoustic cavity, are damped with a DVA treatment, the dot-product method tune multiple HRs to a near-optimal solution over a broad frequency range (40-160 Hz). An adaptive HR prototype with variable opening is built and characterized. Experiments conducted on the cylinder prototype with eight AHRs demonstrate the ability of resonators adapted with the dot-product method to converge to near-optimal noise attenuation in a frequency band including multiple resonances.

Electro-mechanical control of an on-chip optical beam splitter containing an embedded quantum emitter

NASA Astrophysics Data System (ADS)

Bishop, Z. K.; Foster, A. P.; Royall, B.; Bentham, C.; Clarke, E.; Skolnick, M. S.; Wilson, L. R.

2018-05-01

We demonstrate electro-mechanical control of an on-chip GaAs optical beam splitter containing a quantum dot single-photon source. The beam splitter consists of two nanobeam waveguides, which form a directional coupler (DC). The splitting ratio of the DC is controlled by varying the out-of-plane separation of the two waveguides using electro-mechanical actuation. We reversibly tune the beam splitter between an initial state, with emission into both output arms, and a final state with photons emitted into a single output arm. The device represents a compact and scalable tuning approach for use in III-V semiconductor integrated quantum optical circuits.

Elastic metamaterials for tuning circular polarization of electromagnetic waves

PubMed Central

Zárate, Yair; Babaee, Sahab; Kang, Sung H.; Neshev, Dragomir N.; Shadrivov, Ilya V.; Bertoldi, Katia; Powell, David A.

2016-01-01

Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed. PMID:27320212

Single-mode, narrow-linewidth external cavity quantum cascade laser through optical feedback from a partial-reflector.

PubMed

Cendejas, Richard A; Phillips, Mark C; Myers, Tanya L; Taubman, Matthew S

2010-12-06

An external-cavity (EC) quantum cascade (QC) laser using optical feedback from a partial-reflector is reported. With this configuration, the otherwise multi-mode emission of a Fabry-Perot QC laser was made single-mode with optical output powers exceeding 40 mW. A mode-hop free tuning range of 2.46 cm(-1) was achieved by synchronously tuning the EC length and QC laser current. The linewidth of the partial-reflector EC-QC laser was measured for integration times from 100 μs to 4 seconds, and compared to a distributed feedback QC laser. Linewidths as small as 480 kHz were recorded for the EC-QC laser.

Backstepping sliding mode control with functional tuning based on an instantaneous power approach applied to an underwater vehicle

NASA Astrophysics Data System (ADS)

Santos, Carlos Henrique Farias dos; Cildoz, Mariana Uzeda; Terra, Marco Henrique; De Pieri, Edson Roberto

2018-03-01

In this paper, we present a modified backstepping sliding mode control to deal with Euler-Lagrange systems. The controller is applied in an underwater vehicle in order to show the effectiveness of the approach proposed. Instantaneous power data provided by the propulsion system are used to tune the controller in order to guarantee robust performance and energy saving. Thanks to the combination of an internal Proportional Integral and Derivative (PID) controller, it is possible implement high gains to deal with the influence of disturbances and uncertainties. A comparative study among this backstepping sliding mode controller and standard sliding mode controls is presented.

Elastic metamaterials for tuning circular polarization of electromagnetic waves.

PubMed

Zárate, Yair; Babaee, Sahab; Kang, Sung H; Neshev, Dragomir N; Shadrivov, Ilya V; Bertoldi, Katia; Powell, David A

2016-06-20

Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed.

Three-dimensional cavity nanoantennas with resonant-enhanced surface plasmons as dynamic color-tuning reflectors.

PubMed

Fan, J R; Wu, W G; Chen, Z J; Zhu, J; Li, J

2017-03-09

As plasmonic antennas for surface-plasmon-assisted control of optical fields at specific frequencies, metallic nanostructures have recently emerged as crucial optical components for fascinating plasmonic color engineering. Particularly, plasmonic resonant nanocavities can concentrate lightwave energy to strongly enhance light-matter interactions, making them ideal candidates as optical elements for fine-tuning color displays. Inspired by the color mixing effect found on butterfly wings, a new type of plasmonic, multiresonant, narrow-band (the minimum is about 45 nm), high-reflectance (the maximum is about 95%), and dynamic color-tuning reflector is developed. This is achieved from periodic patterns of plasmonic resonant nanocavities in free-standing capped-pillar nanostructure arrays. Such cavity-coupling structures exhibit multiple narrow-band selective and continuously tunable reflections via plasmon standing-wave resonances. Consequently, they can produce a variety of dark-field vibrant reflective colors with good quality, strong color signal and fine tonal variation at the optical diffraction limit. This proposed multicolor scheme provides an elegant strategy for realizing personalized and customized applications in ultracompact photonic data storage and steganography, colorimetric sensing, 3D holograms and other plasmon-assisted photonic devices.

Data fitting and image fine-tuning approach to solve the inverse problem in fluorescence molecular imaging

NASA Astrophysics Data System (ADS)

Gorpas, Dimitris; Politopoulos, Kostas; Yova, Dido; Andersson-Engels, Stefan

2008-02-01

One of the most challenging problems in medical imaging is to "see" a tumour embedded into tissue, which is a turbid medium, by using fluorescent probes for tumour labeling. This problem, despite the efforts made during the last years, has not been fully encountered yet, due to the non-linear nature of the inverse problem and the convergence failures of many optimization techniques. This paper describes a robust solution of the inverse problem, based on data fitting and image fine-tuning techniques. As a forward solver the coupled radiative transfer equation and diffusion approximation model is proposed and compromised via a finite element method, enhanced with adaptive multi-grids for faster and more accurate convergence. A database is constructed by application of the forward model on virtual tumours with known geometry, and thus fluorophore distribution, embedded into simulated tissues. The fitting procedure produces the best matching between the real and virtual data, and thus provides the initial estimation of the fluorophore distribution. Using this information, the coupled radiative transfer equation and diffusion approximation model has the required initial values for a computational reasonable and successful convergence during the image fine-tuning application.

Enhancing long-term memory with stimulation tunes visual attention in one trial.

PubMed

Reinhart, Robert M G; Woodman, Geoffrey F

2015-01-13

Scientists have long proposed that memory representations control the mechanisms of attention that focus processing on the task-relevant objects in our visual field. Modern theories specifically propose that we rely on working memory to store the object representations that provide top-down control over attentional selection. Here, we show that the tuning of perceptual attention can be sharply accelerated after 20 min of noninvasive brain stimulation over medial-frontal cortex. Contrary to prevailing theories of attention, these improvements did not appear to be caused by changes in the nature of the working memory representations of the search targets. Instead, improvements in attentional tuning were accompanied by changes in an electrophysiological signal hypothesized to index long-term memory. We found that this pattern of effects was reliably observed when we stimulated medial-frontal cortex, but when we stimulated posterior parietal cortex, we found that stimulation directly affected the perceptual processing of the search array elements, not the memory representations providing top-down control. Our findings appear to challenge dominant theories of attention by demonstrating that changes in the storage of target representations in long-term memory may underlie rapid changes in the efficiency with which humans can find targets in arrays of objects.

Design of a PID Controller for a PCR Micro Reactor

ERIC Educational Resources Information Center

Dinca, M. P.; Gheorghe, M.; Galvin, P.

2009-01-01

Proportional-integral-derivative (PID) controllers are widely used in process control, and consequently they are described in most of the textbooks on automatic control. However, rather than presenting the overall design process, the examples given in such textbooks are intended to illuminate specific focused aspects of selection, tuning and…

Implicit Affective Cues and Attentional Tuning: An Integrative Review

ERIC Educational Resources Information Center

Friedman, Ronald S.; Forster, Jens

2010-01-01

A large and growing number of studies support the notion that arousing positive emotional states expand, and that arousing negative states constrict, the scope of attention on both the perceptual and conceptual levels. However, these studies have predominantly involved the manipulation or measurement of conscious emotional experiences (e.g.,…

Sensory integration: neuronal filters for polarized light patterns.

PubMed

Krapp, Holger G

2014-09-22

Animal and human behaviour relies on local sensory signals that are often ambiguous. A new study shows how tuning neuronal responses to celestial cues helps locust navigation, demonstrating a common principle of sensory information processing: the use of matched filters. Copyright © 2014 Elsevier Ltd. All rights reserved.

Chalcogenide glass microlenses by inkjet printing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez, Eric A.; Waldmann, Maike; Arnold, Craig B.

We demonstrate micrometer scale mid-IR lenses for integrated optics, using solution-based inkjet printing techniques and subsequent processing. Arsenic sulfide spherical microlenses with diameters of 10-350 {mu}m and focal lengths of 10-700 {mu}m have been fabricated. The baking conditions can be used to tune the precise focal length.

Dynamic and thermal response finite element models of multi-body space structural configurations

NASA Technical Reports Server (NTRS)

Edighoffer, Harold H.

1987-01-01

Presented is structural dynamics modeling of two multibody space structural configurations. The first configuration is a generic space station model of a cylindrical habitation module, two solar array panels, radiator panel, and central connecting tube. The second is a 15-m hoop-column antenna. Discussed is the special joint elimination sequence used for these large finite element models, so that eigenvalues could be extracted. The generic space station model aided test configuration design and analysis/test data correlation. The model consisted of six finite element models, one of each substructure and one of all substructures as a system. Static analysis and tests at the substructure level fine-tuned the finite element models. The 15-m hoop-column antenna is a truss column and structural ring interconnected with tension stabilizing cables. To the cables, pretensioned mesh membrane elements were attached to form four parabolic shaped antennae, one per quadrant. Imposing thermal preloads in the cables and mesh elements produced pretension in the finite element model. Thermal preload variation in the 96 control cables was adjusted to maintain antenna shape within the required tolerance and to give pointing accuracy.

Translating the Elements of Health Governance for Integrated Care from Theory to Practice: A Case Study Approach.

PubMed

Nicholson, Caroline; Hepworth, Julie; Burridge, Letitia; Marley, John; Jackson, Claire

2018-01-31

Against a paucity of evidence, a model describing elements of health governance best suited to achieving integrated care internationally was developed. The aim of this study was to explore how health meso-level organisations used, or planned to use, the governance elements. A case study design was used to offer two contrasting contexts of health governance. Semi-structured interviews were conducted with participants who held senior governance roles. Data were thematically analysed to identify if the elements of health governance were being used, or intended to be in the future. While all participants agreed that the ten elements were essential to developing future integrated care, most were not used. Three major themes were identified: (1) organisational versus system focus, (2) leadership and culture, and, (3) community (dis)engagement. Several barriers and enablers to the use of the elements were identified and would require addressing in order to make evidence-based changes. Despite a clear international policy direction in support of integrated care this study identified a number of significant barriers to its implementation. The study reconfirmed that a focus on all ten elements of health governance is essential to achieve integrated care.

Performance of a Single Liquid Column Damper for the Control of Dynamic Responses of a Tension Leg Platform

NASA Astrophysics Data System (ADS)

Jaksic, V.; Wright, C.; Chanayil, Afeef; Faruque Ali, Shaikh; Murphy, Jimmy; Pakrashi, Vikram

2015-07-01

Tuned liquid column dampers have been proved to be successful in mitigating the dynamic responses of civil infrastructure. There have been some recent applications of this concept on wind turbines and this passive control system can help to mitigate responses of offshore floating platforms and wave devices. The control of dynamic responses of these devices is important for reducing loads on structural elements and facilitating operations and maintenance (O&M) activities. This paper outlines the use of a tuned single liquid column damper for the control of a tension leg platform supported wind turbine. Theoretical studies were carried out and a scaled model was tested in a wave basin to assess the performance of the damper. The tests on the model presented in this paper correspond to a platform with a very low natural frequency for surge, sway and yaw motions. For practical purposes, it was not possible to tune the liquid damper exactly to this frequency. The consequent approach taken and the efficiency of such approach are presented in this paper. Responses to waves of a single frequency are investigated along with responses obtained from wave spectra characterising typical sea states. The extent of control is quantified using peak and root mean squared dynamic responses respectively. The tests present some guidelines and challenges for testing scaled devices in relation to including response control mechanisms. Additionally, the results provide a basis for dictating future research on tuned liquid column damper based control on floating platforms.

Performance Enhancement of Tunable Bandpass Filters Using Selective Etched Ferroelectric Thin Films

NASA Technical Reports Server (NTRS)

Miranda, Felix A.; Mueller, Carl H.; VanKeuls, Fred W.; Subramanyam, Guru; Vignesparamoorthy, Sivaruban

2003-01-01

The inclusion of voltage-tunable barium strontium titanate (BSTO) thin films into planar band pass filters offers tremendous potential to increase their versatility. The ability to tune the passband so as to correct for minor deviations in manufacturing tolerances, or to completely reconfigure the operating frequencies of a microwave communication system, are highly sought-after goals. However, use of ferroelectric films in these devices results in higher dielectric losses, which in turn increase the insertion loss and decrease the quality factors of the filters. This study explores the use of patterned ferroelectric layers to minimize dielectric losses without degrading tunability. Patterning the ferroelectric layers enables us to constrict the width of the ferroelectric layers between the coupled microstrip lines, and minimize losses due to ferroelectric layers. Coupled one-pole microstrip bandpass filters with fundamental resonances at approx. 7.2 GHz and well defined harmonic resonances at approx. 14.4 and approx. 21.6 GHz, were designed, simulated and tested. For one of the filters, experimental results verified that its center frequency was tunable by 528 MHz at a center frequency of 21.957 GHz, with insertion losses varying from 4.3 to 2.5 dB, at 0 and 3.5 V/micron, respectively. These data demonstrate that the tuning-to-loss figure of merit of tunable microstrip filters can be greatly improved using patterned ferroelectric thin films as the tuning element, and tuning can be controlled by engineering the ferroelectric constriction in the coupled sections.

Heterogeneously-integrated VCSEL using high-contrast grating on silicon

NASA Astrophysics Data System (ADS)

Ferrara, James; Zhu, Li; Yang, Weijian; Qiao, Pengfei; Chang-Hasnain, Connie J.

2015-02-01

We present a unique heterogeneous integration approach for VCSELs on silicon using eutectic bonding. An electrically pumped III-V - silicon heterogeneous VCSEL is demonstrated using a high-contrast grating (HCG) reflector on silicon. CW output power >1.5 mW, thermal resistance of 1.46 K/mW, and 5 Gb/s direct modulation is demonstrated. We also explore the possibility of an all-HCG VCSEL structure that would benefit from stronger thermal performance, larger tuning efficiency, and higher direct modulation speeds.

Mobile robot exploration and navigation of indoor spaces using sonar and vision

NASA Technical Reports Server (NTRS)

Kortenkamp, David; Huber, Marcus; Koss, Frank; Belding, William; Lee, Jaeho; Wu, Annie; Bidlack, Clint; Rodgers, Seth

1994-01-01

Integration of skills into an autonomous robot that performs a complex task is described. Time constraints prevented complete integration of all the described skills. The biggest problem was tuning the sensor-based region-finding algorithm to the environment involved. Since localization depended on matching regions found with the a priori map, the robot became lost very quickly. If the low level sensing of the world is not working, then high level reasoning or map making will be unsuccessful.

Smart Phase Tuning in Microwave Photonic Integrated Circuits Toward Automated Frequency Multiplication by Design

NASA Astrophysics Data System (ADS)

Nabavi, N.

2018-07-01

The author investigates the monitoring methods for fine adjustment of the previously proposed on-chip architecture for frequency multiplication and translation of harmonics by design. Digital signal processing (DSP) algorithms are utilized to create an optimized microwave photonic integrated circuit functionality toward automated frequency multiplication. The implemented DSP algorithms are formed on discrete Fourier transform and optimization-based algorithms (Greedy and gradient-based algorithms), which are analytically derived and numerically compared based on the accuracy and speed of convergence criteria.

Weak Galerkin finite element methods for Darcy flow: Anisotropy and heterogeneity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Guang; Liu, Jiangguo; Mu, Lin

2014-11-01

This paper presents a family of weak Galerkin finite element methods (WGFEMs) for Darcy flow computation. The WGFEMs are new numerical methods that rely on the novel concept of discrete weak gradients. The WGFEMs solve for pressure unknowns both in element interiors and on the mesh skeleton. The numerical velocity is then obtained from the discrete weak gradient of the numerical pressure. The new methods are quite different than many existing numerical methods in that they are locally conservative by design, the resulting discrete linear systems are symmetric and positive-definite, and there is no need for tuning problem-dependent penalty factors.more » We test the WGFEMs on benchmark problems to demonstrate the strong potential of these new methods in handling strong anisotropy and heterogeneity in Darcy flow.« less

Optical phased arrays with evanescently-coupled antennas

DOEpatents

Sun, Jie; Watts, Michael R; Yaacobi, Ami; Timurdogan, Erman

2015-03-24

An optical phased array formed of a large number of nanophotonic antenna elements can be used to project complex images into the far field. These nanophotonic phased arrays, including the nanophotonic antenna elements and waveguides, can be formed on a single chip of silicon using complementary metal-oxide-semiconductor (CMOS) processes. Directional couplers evanescently couple light from the waveguides to the nanophotonic antenna elements, which emit the light as beams with phases and amplitudes selected so that the emitted beams interfere in the far field to produce the desired pattern. In some cases, each antenna in the phased array may be optically coupled to a corresponding variable delay line, such as a thermo-optically tuned waveguide or a liquid-filled cell, which can be used to vary the phase of the antenna's output (and the resulting far-field interference pattern).

Disposable Plasmonics: Plastic Templated Plasmonic Metamaterials with Tunable Chirality.

PubMed

Karimullah, Affar S; Jack, Calum; Tullius, Ryan; Rotello, Vincent M; Cooke, Graeme; Gadegaard, Nikolaj; Barron, Laurence D; Kadodwala, Malcolm

2015-10-07

Development of low-cost disposable plasmonic substrates is vital for the applicability of plasmonic sensing. Such devices can be made using injection-molded templates to create plasmonic films. The elements of these plasmonic films are hybrid nanostructures composed of inverse and solid structures. Tuning the modal coupling between the two allows optimization of the optical properties for nanophotonic applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The NuMI neutrino beam

DOE PAGES

Adamson, P.; Anderson, K.; Andrews, M.; ...

2015-10-20

Our paper describes the hardware and operations of the Neutrinos at the Main Injector (NuMI) beam at Fermilab. It elaborates on the design considerations for the beam as a whole and for individual elements. The most important part of our design details pertaining to individual components is described. Beam monitoring systems and procedures, including the tuning and alignment of the beam and NuMI long-term performance, are also discussed.

Embedded Meta-Material Antennas

DTIC Science & Technology

2009-01-31

influence of the overall capacitance . Based on the tunable SRRs, we designed a tunable loop antenna with SRRs and HPTs as tuning elements. In this case, we...are those of the authors) and should not be construed as an official Department of the Army position, policy or decision, unless so designated by...single aperture, which can provide significant miniaturization and flexibility to the entire system. To design such miniaturized antennas, new materials

Two dimensional thermo-optic beam steering using a silicon photonic optical phased array

NASA Astrophysics Data System (ADS)

Mahon, Rita; Preussner, Marcel W.; Rabinovich, William S.; Goetz, Peter G.; Kozak, Dmitry A.; Ferraro, Mike S.; Murphy, James L.

2016-03-01

Components for free space optical communication terminals such as lasers, amplifiers, and receivers have all seen substantial reduction in both size and power consumption over the past several decades. However, pointing systems, such as fast steering mirrors and gimbals, have remained large, slow and power-hungry. Optical phased arrays provide a possible solution for non-mechanical beam steering devices that can be compact and lower in power. Silicon photonics is a promising technology for phased arrays because it has the potential to scale to many elements and may be compatible with CMOS technology thereby enabling batch fabrication. For most free space optical communication applications, two-dimensional beam steering is needed. To date, silicon photonic phased arrays have achieved two-dimensional steering by combining thermo-optic steering, in-plane, with wavelength tuning by means of an output grating to give angular tuning, out-of-plane. While this architecture might work for certain static communication links, it would be difficult to implement for moving platforms. Other approaches have required N2 controls for an NxN element phased array, which leads to complexity. Hence, in this work we demonstrate steering using the thermo-optic effect for both dimensions with a simplified steering mechanism requiring only two control signals, one for each steering dimension.

Development of a finite element model of the middle ear.

PubMed

Williams, K R; Blayney, A W; Rice, H J

1996-01-01

A representative finite element model of the healthy ear is developed commencing with a description of the decoupled isotropic tympanic membrane. This model was shown to vibrate in a manner similar to that found both numerically (1, 2) and experimentally (8). The introduction of a fibre system into the membrane matrix significantly altered the modes of vibration. The first mode "remains as a piston like movement as for the isotropic membrane. However, higher modes show a simpler vibration pattern similar to the second mode but with a varying axis of movement and lower amplitudes. The introduction of a malleus and incus does not change the natural frequencies or mode shapes of the membrane for certain support conditions. When constraints are imposed along the ossicular chain by simulation of a cochlear impedance term then significantly altered modes can occur. More recently a revised model of the ear has been developed by the inclusion of the outer ear canal. This discretisation uses geometries extracted from a Nuclear Magnetic resonance scan of a healthy subject and a crude inner ear model using stiffness parameters ultimately fixed through a parameter tuning process. The subsequently tuned model showed behaviour consistent with previous findings and should provide a good basis for subsequent modelling of diseased ears and assessment of the performance of middle ear prostheses.

Measured and calculated acoustic attenuation rates of tuned resonator arrays for two surface impedance distribution models with flow

NASA Technical Reports Server (NTRS)

Parrott, Tony L.; Abrahamson, A. Louis; Jones, Michael G.

1988-01-01

An experiment was performed to validate two analytical models for predicting low frequency attenuation of duct liner configurations built from an array of seven resonators that could be individually tuned via adjustable cavity depths. These analytical models had previously been developed for high frequency aero-engine inlet duct liner design. In the low frequency application, the liner surface impedance distribution is unavoidably spatially varying by virtue of available fabrication techniques. The characteristic length of this spatial variation may be a significant fraction of the acoustic wavelength. Comparison of measured and predicted attenuation rates and transmission losses for both modal decomposition and finite element propagation models were in good to excellent agreement for a test frequency range that included the first and second cavity resonance frequencies. This was true for either of two surface impedance distribution modeling procedures used to simplify the impedance boundary conditions. In the presence of mean flow, measurements revealed a fine scale structure of acoustic hot spots in the attenuation and phase profiles. These details were accurately predicted by the finite element model. Since no impedance changes due to mean flow were assumed, it is concluded that this fine scale structure was due to convective effects of the mean flow interacting with the surface impedance nonuniformities.

On the tuning of electrical and thermal transport in thermoelectrics: an integrated theory–experiment perspective

DOE PAGES

Yang, Jiong; Xi, Lili; Qiu, Wujie; ...

2016-02-26

During the last two decades, we have witnessed great progress in research on thermoelectrics. There are two primary focuses. One is the fundamental understanding of electrical and thermal transport, enabled by the interplay of theory and experiment; the other is the substantial enhancement of the performance of various thermoelectric materials, through synergistic optimisation of those intercorrelated transport parameters. In this article, we review some of the successful strategies for tuning electrical and thermal transport. For electrical transport, we start from the classical but still very active strategy of tuning band degeneracy (or band convergence), then discuss the engineering of carriermore » scattering, and finally address the concept of conduction channels and conductive networks that emerge in complex thermoelectric materials. For thermal transport, we summarise the approaches for studying thermal transport based on phonon–phonon interactions valid for conventional solids, as well as some quantitative efforts for nanostructures. We also discuss the thermal transport in complex materials with chemical-bond hierarchy, in which a portion of the atoms (or subunits) are weakly bonded to the rest of the structure, leading to an intrinsic manifestation of part-crystalline part-liquid state at elevated temperatures. In this review, we provide a summary of achievements made in recent studies of thermoelectric transport properties, and demonstrate how they have led to improvements in thermoelectric performance by the integration of modern theory and experiment, and point out some challenges and possible directions.« less

Algorithm sensitivity analysis and parameter tuning for tissue image segmentation pipelines

PubMed Central

Kurç, Tahsin M.; Taveira, Luís F. R.; Melo, Alba C. M. A.; Gao, Yi; Kong, Jun; Saltz, Joel H.

2017-01-01

Abstract Motivation: Sensitivity analysis and parameter tuning are important processes in large-scale image analysis. They are very costly because the image analysis workflows are required to be executed several times to systematically correlate output variations with parameter changes or to tune parameters. An integrated solution with minimum user interaction that uses effective methodologies and high performance computing is required to scale these studies to large imaging datasets and expensive analysis workflows. Results: The experiments with two segmentation workflows show that the proposed approach can (i) quickly identify and prune parameters that are non-influential; (ii) search a small fraction (about 100 points) of the parameter search space with billions to trillions of points and improve the quality of segmentation results (Dice and Jaccard metrics) by as much as 1.42× compared to the results from the default parameters; (iii) attain good scalability on a high performance cluster with several effective optimizations. Conclusions: Our work demonstrates the feasibility of performing sensitivity analyses, parameter studies and auto-tuning with large datasets. The proposed framework can enable the quantification of error estimations and output variations in image segmentation pipelines. Availability and Implementation: Source code: https://github.com/SBU-BMI/region-templates/. Contact: teodoro@unb.br Supplementary information: Supplementary data are available at Bioinformatics online. PMID:28062445

Algorithm sensitivity analysis and parameter tuning for tissue image segmentation pipelines.

PubMed

Teodoro, George; Kurç, Tahsin M; Taveira, Luís F R; Melo, Alba C M A; Gao, Yi; Kong, Jun; Saltz, Joel H

2017-04-01

Sensitivity analysis and parameter tuning are important processes in large-scale image analysis. They are very costly because the image analysis workflows are required to be executed several times to systematically correlate output variations with parameter changes or to tune parameters. An integrated solution with minimum user interaction that uses effective methodologies and high performance computing is required to scale these studies to large imaging datasets and expensive analysis workflows. The experiments with two segmentation workflows show that the proposed approach can (i) quickly identify and prune parameters that are non-influential; (ii) search a small fraction (about 100 points) of the parameter search space with billions to trillions of points and improve the quality of segmentation results (Dice and Jaccard metrics) by as much as 1.42× compared to the results from the default parameters; (iii) attain good scalability on a high performance cluster with several effective optimizations. Our work demonstrates the feasibility of performing sensitivity analyses, parameter studies and auto-tuning with large datasets. The proposed framework can enable the quantification of error estimations and output variations in image segmentation pipelines. Source code: https://github.com/SBU-BMI/region-templates/ . teodoro@unb.br. Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press.

Antenna Linear-Quadratic-Gaussian (LQG) Controllers: Properties, Limits of Performance, and Tuning Procedure

NASA Technical Reports Server (NTRS)

Gawronski, W.

2004-01-01

Wind gusts are the main disturbances that depreciate tracking precision of microwave antennas and radiotelescopes. The linear-quadratic-Gaussian (LQG) controllers - as compared with the proportional-and-integral (PI) controllers significantly improve the tracking precision in wind disturbances. However, their properties have not been satisfactorily understood; consequently, their tuning is a trial-and-error process. A control engineer has two tools to tune an LQG controller: the choice of coordinate system of the controller model and the selection of weights of the LQG performance index. This article analyzes properties of an open- and closed-loop antenna. It shows that the proper choice of coordinates of the open-loop model simplifies the shaping of the closed-loop performance. The closed-loop properties are influenced by the LQG weights. The article shows the impact of the weights on the antenna closed-loop bandwidth, disturbance rejection properties, and antenna acceleration. The bandwidth and the disturbance rejection characterize the antenna performance, while the acceleration represents the performance limit set by the antenna hardware (motors). The article presents the controller tuning procedure, based on the coordinate selection and the weight properties. The procedure rationally shapes the closed-loop performance, as an alternative to the trial-and-error approach.

Optimal Self-Tuning PID Controller Based on Low Power Consumption for a Server Fan Cooling System.

PubMed

Lee, Chengming; Chen, Rongshun

2015-05-20

Recently, saving the cooling power in servers by controlling the fan speed has attracted considerable attention because of the increasing demand for high-density servers. This paper presents an optimal self-tuning proportional-integral-derivative (PID) controller, combining a PID neural network (PIDNN) with fan-power-based optimization in the transient-state temperature response in the time domain, for a server fan cooling system. Because the thermal model of the cooling system is nonlinear and complex, a server mockup system simulating a 1U rack server was constructed and a fan power model was created using a third-order nonlinear curve fit to determine the cooling power consumption by the fan speed control. PIDNN with a time domain criterion is used to tune all online and optimized PID gains. The proposed controller was validated through experiments of step response when the server operated from the low to high power state. The results show that up to 14% of a server's fan cooling power can be saved if the fan control permits a slight temperature response overshoot in the electronic components, which may provide a time-saving strategy for tuning the PID controller to control the server fan speed during low fan power consumption.

Opponent Coding of Sound Location (Azimuth) in Planum Temporale is Robust to Sound-Level Variations.

PubMed

Derey, Kiki; Valente, Giancarlo; de Gelder, Beatrice; Formisano, Elia

2016-01-01

Coding of sound location in auditory cortex (AC) is only partially understood. Recent electrophysiological research suggests that neurons in mammalian auditory cortex are characterized by broad spatial tuning and a preference for the contralateral hemifield, that is, a nonuniform sampling of sound azimuth. Additionally, spatial selectivity decreases with increasing sound intensity. To accommodate these findings, it has been proposed that sound location is encoded by the integrated activity of neuronal populations with opposite hemifield tuning ("opponent channel model"). In this study, we investigated the validity of such a model in human AC with functional magnetic resonance imaging (fMRI) and a phase-encoding paradigm employing binaural stimuli recorded individually for each participant. In all subjects, we observed preferential fMRI responses to contralateral azimuth positions. Additionally, in most AC locations, spatial tuning was broad and not level invariant. We derived an opponent channel model of the fMRI responses by subtracting the activity of contralaterally tuned regions in bilateral planum temporale. This resulted in accurate decoding of sound azimuth location, which was unaffected by changes in sound level. Our data thus support opponent channel coding as a neural mechanism for representing acoustic azimuth in human AC. © The Author 2015. Published by Oxford University Press.

The implementation of integrated care: the empirical validation of the Development Model for Integrated Care

PubMed Central

2011-01-01

Background Integrated care is considered as a strategy to improve the delivery, efficiency, client outcomes and satisfaction rates of health care. To integrate the care from multiple providers into a coherent client-focused service, a large number of activities and agreements have to be implemented like streamlining information flows and patient transfers. The Development Model for Integrated care (DMIC) describes nine clusters containing in total 89 elements that contribute to the integration of care. We have empirically validated this model in practice by assessing the relevance, implementation and plans of the elements in three integrated care service settings in The Netherlands: stroke, acute myocardial infarct (AMI), and dementia. Methods Based on the DMIC, a survey was developed for integrated care coordinators. We invited all Dutch stroke and AMI-services, as well as the dementia care networks to participate, of which 84 did (response rate 83%). Data were collected on relevance, presence, and year of implementation of the 89 elements. The data analysis was done by means of descriptive statistics, Chi Square, ANOVA and Kruskal-Wallis H tests. Results The results indicate that the integrated care practice organizations in all three care settings rated the nine clusters and 89 elements of the DMIC as highly relevant. The average number of elements implemented was 50 ± 18, 42 ± 13, and 45 ± 22 for stroke, acute myocardial infarction, and dementia care services, respectively. Although the dementia networks were significantly younger, their numbers of implemented elements were comparable to those of the other services. The analyses of the implementation timelines showed that the older integrated care services had fewer plans for further implementation than the younger ones. Integrated care coordinators stated that the DMIC helped them to assess their integrated care development in practice and supported them in obtaining ideas for expanding their integrated care activities. Conclusions Although the patient composites and the characteristics of the 84 participating integrated care services differed considerably, the results confirm that the clusters and the vast majority of DMIC elements are relevant to all three groups. Therefore, the DMIC can serve as a general quality management tool for integrated care. Applying the model in practice can help in steering further implementations as well as the development of new integrated care practices. PMID:21801428

The implementation of integrated care: the empirical validation of the Development Model for Integrated care.

PubMed

Minkman, Mirella M N; Vermeulen, Robbert P; Ahaus, Kees T B; Huijsman, Robbert

2011-07-30

Integrated care is considered as a strategy to improve the delivery, efficiency, client outcomes and satisfaction rates of health care. To integrate the care from multiple providers into a coherent client-focused service, a large number of activities and agreements have to be implemented like streamlining information flows and patient transfers. The Development Model for Integrated care (DMIC) describes nine clusters containing in total 89 elements that contribute to the integration of care. We have empirically validated this model in practice by assessing the relevance, implementation and plans of the elements in three integrated care service settings in The Netherlands: stroke, acute myocardial infarct (AMI), and dementia. Based on the DMIC, a survey was developed for integrated care coordinators. We invited all Dutch stroke and AMI-services, as well as the dementia care networks to participate, of which 84 did (response rate 83%). Data were collected on relevance, presence, and year of implementation of the 89 elements. The data analysis was done by means of descriptive statistics, Chi Square, ANOVA and Kruskal-Wallis H tests. The results indicate that the integrated care practice organizations in all three care settings rated the nine clusters and 89 elements of the DMIC as highly relevant. The average number of elements implemented was 50 ± 18, 42 ± 13, and 45 ± 22 for stroke, acute myocardial infarction, and dementia care services, respectively. Although the dementia networks were significantly younger, their numbers of implemented elements were comparable to those of the other services. The analyses of the implementation timelines showed that the older integrated care services had fewer plans for further implementation than the younger ones. Integrated care coordinators stated that the DMIC helped them to assess their integrated care development in practice and supported them in obtaining ideas for expanding their integrated care activities. Although the patient composites and the characteristics of the 84 participating integrated care services differed considerably, the results confirm that the clusters and the vast majority of DMIC elements are relevant to all three groups. Therefore, the DMIC can serve as a general quality management tool for integrated care. Applying the model in practice can help in steering further implementations as well as the development of new integrated care practices.

Workshop on the Integration of Finite Element Modeling with Geometric Modeling

NASA Technical Reports Server (NTRS)

Wozny, Michael J.

1987-01-01

The workshop on the Integration of Finite Element Modeling with Geometric Modeling was held on 12 May 1987. It was held to discuss the geometric modeling requirements of the finite element modeling process and to better understand the technical aspects of the integration of these two areas. The 11 papers are presented except for one for which only the abstract is given.