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Sample records for pointer driven microheater

  1. Microheater Array Boiling Experiment

    NASA Technical Reports Server (NTRS)

    Kim, Jungho; McQuillen, John; Balombin, Joe

    2002-01-01

    By conducting pool boiling tests in microgravity, the effect of buoyancy on the overall boiling process and the relative magnitude of other phenomena can be assessed. Data from KC-135 and sounding rocket experiments indicate little effect of gravity on boiling heat transfer at wall superheats below 25 C, despite vast differences in bubble behavior between gravity levels. In microgravity, a large primary bubble, surrounded by smaller satellite bubbles, moved over the surface, occasionally causing nucleation. Once formed, the primary bubble size remained constant for a given superheat, indicating evaporation at the bubble base is balanced with condensation on the bubble cap. The primary bubble's size increased with wall superheat. Most heaters under the primary bubble had low heat transfer rates, suggesting liquid dryout. Strong Marangoni convection developed in microgravity, forming a 'jet' into the bulk liquid that forced the bubble onto the heater. An experiment is being designed for the. Microgravity Science Glovebox. This experiment uses two 96 element microheater arrays, 2.7 and 7.0 mm in size. These heaters are individually controlled to operate at a constant temperature, measuring local heat fluxes as a function of time and space. Most boiling experiments operate at constant wall heat flux with larger heaters, allowing only time and space-averaged measurements. Each heater is about the bubble departure size in normal gravity, but significantly smaller than the bubble departure size in reduced gravity.

  2. Tin Oxide Microheater for Chemical Sensors

    NASA Astrophysics Data System (ADS)

    Gharesi, Mohsen; Ansari, Mohammad

    2016-03-01

    Tin oxide is the main material utilized for the fabrication of chemical sensing pellets which operate at elevated temperatures. The heating is commonly carried out with ruthenium dioxide resistors. Here, a tin oxide-based microheater is developed for microsensor applications. These microheaters are fabricated on 0.5 mm thick alumina substrates using spray pyrolysis technique. The optimum SnO2 heaters have a sheet resistivity in the 40-70 Ω/a range. Ohmic Ag/SnO2 contacts are formed by silver paste printing followed by an appropriate thermal annealing, which provide connections to the external circuitry. Durability tests are carried out on several samples; the long-term performance of the fabricated devices is satisfactory. The method allows the elimination of the expensive ruthenium dioxide from the structure of generic gas sensors.

  3. Polydimethylsiloxane microfluidic chip with integrated microheater and thermal sensor

    PubMed Central

    Wu, Jinbo; Cao, Wenbin; Wen, Weijia; Chang, Donald Choy; Sheng, Ping

    2009-01-01

    A microheater and a thermal sensor were fabricated inside elastomeric polydimethylsiloxane microchannels by injecting silver paint (or other conductive materials) into the channels. With a high-precision control scheme, microheaters can be used for rapid heating, with precise temperature control and uniform thermal distribution. Using such a microheater and feedback system, a polymerase chain reaction experiment was carried out whereas the DNA was successfully amplified in 25 cycles, with 1 min per cycle. PMID:19693386

  4. X-ray beam pointer

    NASA Technical Reports Server (NTRS)

    Nelson, C. W.

    1980-01-01

    Inexpensive, readily assembled pointer aims X-ray machine for welded assembly radiographs. Plumb bob used for vertical alinement and yardstick used to visualize X-ray paths were inconvenient and inaccurate. Pointer cuts alinement time by one-half and eliminates necessity of retakes. For 3,000 weld radiographs, pointer will save 300 worker-hours and significant materials costs.

  5. GNU Fortran Cray Pointer Extension

    2005-07-27

    The gfortran compiler is a Fortran front end to the GNU Compiler Collection. The Cray Pointer extension adds to this existing compiler support for Cray-style integer pointers. This non-standard but widely used extension adds the functionality of C-like pointers to the Fortran language.

  6. Photothermal lesions in soft tissue induced by optical fiber microheaters.

    PubMed

    Pimentel-Domínguez, Reinher; Moreno-Álvarez, Paola; Hautefeuille, Mathieu; Chavarría, Anahí; Hernández-Cordero, Juan

    2016-04-01

    Photothermal therapy has shown to be a promising technique for local treatment of tumors. However, the main challenge for this technique is the availability of localized heat sources to minimize thermal damage in the surrounding healthy tissue. In this work, we demonstrate the use of optical fiber microheaters for inducing thermal lesions in soft tissue. The proposed devices incorporate carbon nanotubes or gold nanolayers on the tips of optical fibers for enhanced photothermal effects and heating of ex vivo biological tissues. We report preliminary results of small size photothermal lesions induced on mice liver tissues. The morphology of the resulting lesions shows that optical fiber microheaters may render useful for delivering highly localized heat for photothermal therapy.

  7. Photothermal lesions in soft tissue induced by optical fiber microheaters.

    PubMed

    Pimentel-Domínguez, Reinher; Moreno-Álvarez, Paola; Hautefeuille, Mathieu; Chavarría, Anahí; Hernández-Cordero, Juan

    2016-04-01

    Photothermal therapy has shown to be a promising technique for local treatment of tumors. However, the main challenge for this technique is the availability of localized heat sources to minimize thermal damage in the surrounding healthy tissue. In this work, we demonstrate the use of optical fiber microheaters for inducing thermal lesions in soft tissue. The proposed devices incorporate carbon nanotubes or gold nanolayers on the tips of optical fibers for enhanced photothermal effects and heating of ex vivo biological tissues. We report preliminary results of small size photothermal lesions induced on mice liver tissues. The morphology of the resulting lesions shows that optical fiber microheaters may render useful for delivering highly localized heat for photothermal therapy. PMID:27446642

  8. Photothermal lesions in soft tissue induced by optical fiber microheaters

    PubMed Central

    Pimentel-Domínguez, Reinher; Moreno-Álvarez, Paola; Hautefeuille, Mathieu; Chavarría, Anahí; Hernández-Cordero, Juan

    2016-01-01

    Photothermal therapy has shown to be a promising technique for local treatment of tumors. However, the main challenge for this technique is the availability of localized heat sources to minimize thermal damage in the surrounding healthy tissue. In this work, we demonstrate the use of optical fiber microheaters for inducing thermal lesions in soft tissue. The proposed devices incorporate carbon nanotubes or gold nanolayers on the tips of optical fibers for enhanced photothermal effects and heating of ex vivo biological tissues. We report preliminary results of small size photothermal lesions induced on mice liver tissues. The morphology of the resulting lesions shows that optical fiber microheaters may render useful for delivering highly localized heat for photothermal therapy. PMID:27446642

  9. Infrared Risley beam pointer

    NASA Astrophysics Data System (ADS)

    Harford, Steven T.; Gutierrez, Homero; Newman, Michael; Pierce, Robert; Quakenbush, Tim; Wallace, John; Bornstein, Michael

    2014-03-01

    Ball Aerospace & Technologies Corp. (BATC) has developed a Risley Beam Pointer (RBP) mechanism capable of agile slewing, accurate pointing and high bandwidth. The RBP is comprised of two wedged prisms that offer a wide Field of Regard (FOR) and may be manufactured and operated with diffraction limited optical quality. The tightly packaged mechanism is capable of steering a 4 inch beam over a 60° half angle cone with better than 60 μrad precision. Absolute accuracy of the beam steering is better than 1 mrad. The conformal nature of the RBP makes it an ideal mechanism for use on low altitude aircraft and unmanned aerial vehicles. Unique aspects of the opto-mechanical design include i) thermal compliance to maintain bearing preload and optical figure over a wide temperature range; and ii) packaging of a remote infrared sensor that periodically reports the temperature of both prisms for accurate determination of the index of refraction. The pointing control system operates each prism independently and employs an inner rate loop nested within an outer position loop. Mathematics for the transformation between line-of-sight coordinates and prism rotation are hosted on a 200 MHz microcontroller with just 516 KB of RAM.

  10. Development of Micro-Heaters with Optimized Temperature Compensation Design for Gas Sensors

    PubMed Central

    Hwang, Woo-Jin; Shin, Kyu-Sik; Roh, Ji-Hyoung; Lee, Dae-Sung; Choa, Sung-Hoon

    2011-01-01

    One of the key components of a chemical gas sensor is a MEMS micro-heater. Micro-heaters are used in both semiconductor gas sensors and NDIR gas sensors; however they each require different heat dissipation characteristics. For the semiconductor gas sensors, a uniform temperature is required over a wide area of the heater. On the other hand, for the NDIR gas sensor, the micro-heater needs high levels of infrared radiation in order to increase sensitivity. In this study, a novel design of a poly-Si micro-heater is proposed to improve the uniformity of heat dissipation on the heating plate. Temperature uniformity of the micro-heater is achieved by compensating for the variation in power consumption around the perimeter of the heater. With the power compensated design, the uniform heating area is increased by 2.5 times and the average temperature goes up by 40 °C. Therefore, this power compensated micro-heater design is suitable for a semiconductor gas sensor. Meanwhile, the poly-Si micro-heater without compensation shows a higher level of infrared radiation under equal power consumption conditions. This indicates that the micro-heater without compensation is more suitable for a NDIR gas sensor. Furthermore, the micro-heater shows a short response time of less than 20ms, indicating a very high efficiency of pulse driving. PMID:22163756

  11. Reduction of thermal emission background in high temperature microheaters

    NASA Astrophysics Data System (ADS)

    Armstrong, Philip R.; Mah, Merlin L.; Olson, Kyle D.; Taylor, Lucas N.; Talghader, Joseph J.

    2016-05-01

    High temperature microheaters have been designed and constructed to reduce the background thermal emission radiation produced by the heater. Such heaters allow one to probe luminescence with very low numbers of photons where the background emission would overwhelm the desired signal. Two methods to reduce background emission are described: one with low emission materials and the other with interference coating design. The first uses platforms composed of material that is transparent to mid-infrared light and therefore of low emissivity. Heating elements are embedded in the periphery of the heater. The transparent platform is composed of aluminum oxide, which is largely transparent for wavelengths less than about 8 μm. In the luminescent microscopy used to test the heater, an optical aperture blocks emission from the heating coils while passing light from the heated objects on the transparent center of the microheater. The amount of infrared light transmitted through the aperture was reduced by 90% as the aperture was moved from the highly emissive heater coils at 450 °C to the largely transparent center at the same temperature. The second method uses microheaters with integrated multilayer interference structures designed to limit background emission in the spectral range of the low-light luminescence object being measured. These heaters were composed of aluminum oxide, titanium dioxide, and platinum and were operated over a large range of temperatures, from 50 °C to 600 °C. At 600 °C, they showed a background photon emission only 1/800 that of a comparison heater without the multilayer interference structure. In this structure, the radiation background was sufficiently reduced to easily monitor weak thermoluminescent emission from CaSO4:Ce,Tb microparticles.

  12. Virus based Full Colour Pixels using a Microheater.

    PubMed

    Kim, Won-Geun; Kim, Kyujung; Ha, Sung-Hun; Song, Hyerin; Yu, Hyun-Woo; Kim, Chuntae; Kim, Jong-Man; Oh, Jin-Woo

    2015-01-01

    Mimicking natural structures has been received considerable attentions, and there have been a few practical advances. Tremendous efforts based on a self-assembly technique have been contributed to the development of the novel photonic structures which are mimicking nature's inventions. We emulate the photonic structures from an origin of colour generation of mammalian skins and avian skin/feathers using M13 phage. The structures can be generated a full range of RGB colours that can be sensitively switched by temperature and substrate materials. Consequently, we developed an M13 phage-based temperature-dependent actively controllable colour pixels platform on a microheater chip. Given the simplicity of the fabrication process, the low voltage requirements and cycling stability, the virus colour pixels enable us to substitute for conventional colour pixels for the development of various implantable, wearable and flexible devices in future. PMID:26334322

  13. Virus based Full Colour Pixels using a Microheater

    NASA Astrophysics Data System (ADS)

    Kim, Won-Geun; Kim, Kyujung; Ha, Sung-Hun; Song, Hyerin; Yu, Hyun-Woo; Kim, Chuntae; Kim, Jong-Man; Oh, Jin-Woo

    2015-09-01

    Mimicking natural structures has been received considerable attentions, and there have been a few practical advances. Tremendous efforts based on a self-assembly technique have been contributed to the development of the novel photonic structures which are mimicking nature’s inventions. We emulate the photonic structures from an origin of colour generation of mammalian skins and avian skin/feathers using M13 phage. The structures can be generated a full range of RGB colours that can be sensitively switched by temperature and substrate materials. Consequently, we developed an M13 phage-based temperature-dependent actively controllable colour pixels platform on a microheater chip. Given the simplicity of the fabrication process, the low voltage requirements and cycling stability, the virus colour pixels enable us to substitute for conventional colour pixels for the development of various implantable, wearable and flexible devices in future.

  14. Virus based Full Colour Pixels using a Microheater

    PubMed Central

    Kim, Won-Geun; Kim, Kyujung; Ha, Sung-Hun; Song, Hyerin; Yu, Hyun-Woo; Kim, Chuntae; Kim, Jong-Man; Oh, Jin-Woo

    2015-01-01

    Mimicking natural structures has been received considerable attentions, and there have been a few practical advances. Tremendous efforts based on a self-assembly technique have been contributed to the development of the novel photonic structures which are mimicking nature’s inventions. We emulate the photonic structures from an origin of colour generation of mammalian skins and avian skin/feathers using M13 phage. The structures can be generated a full range of RGB colours that can be sensitively switched by temperature and substrate materials. Consequently, we developed an M13 phage-based temperature-dependent actively controllable colour pixels platform on a microheater chip. Given the simplicity of the fabrication process, the low voltage requirements and cycling stability, the virus colour pixels enable us to substitute for conventional colour pixels for the development of various implantable, wearable and flexible devices in future. PMID:26334322

  15. Thread Migration in the Presence of Pointers

    NASA Technical Reports Server (NTRS)

    Cronk, David; Haines, Matthew; Mehrotra, Piyush

    1996-01-01

    Dynamic migration of lightweight threads supports both data locality and load balancing. However, migrating threads that contain pointers referencing data in both the stack and heap remains an open problem. In this paper we describe a technique by which threads with pointers referencing both stack and non-shared heap data can be migrated such that the pointers remain valid after migration. As a result, threads containing pointers can now be migrated between processors in a homogeneous distributed memory environment.

  16. Optimization of metallic microheaters for high-speed reconfigurable silicon photonics.

    PubMed

    Atabaki, A H; Shah Hosseini, E; Eftekhar, A A; Yegnanarayanan, S; Adibi, A

    2010-08-16

    The strong thermooptic effect in silicon enables low-power and low-loss reconfiguration of large-scale silicon photonics. Thermal reconfiguration through the integration of metallic microheaters has been one of the more widely used reconfiguration techniques in silicon photonics. In this paper, structural and material optimizations are carried out through heat transport modeling to improve the reconfiguration speed of such devices, and the results are experimentally verified. Around 4 micros reconfiguration time are shown for the optimized structures. Moreover, sub-microsecond reconfiguration time is experimentally demonstrated through the pulsed excitation of the microheaters. The limitation of this pulsed excitation scheme is also discussed through an accurate system-level model developed for the microheater response.

  17. A Light-Activated Microheater for the Remote Control of Enzymatic Catalysis.

    PubMed

    Cao, Yuanyuan; Wang, Zhen; Liao, Shenglong; Wang, Jian; Wang, Yapei

    2016-01-18

    The remote control of enzymatic catalysis is of significant importance in disease treatment and industrial applications. Herein, we designed a microheater composed of a porous polylactic acid (PLA) matrix and polydopamine (PDA) with notable photothermal conversion capability. Starch hydrolysis, catalyzed by using α-amylase, was accelerated in the presence of the microheater under illumination with near-infrared light or natural sunlight at room temperature. Additionally, the methodology was extended to the preparation of microwave-absorbing materials with the deposition of polyaniline on porous PLA matrix. The porous morphology improves the energy-conversion efficiency. PMID:26603499

  18. A Light-Activated Microheater for the Remote Control of Enzymatic Catalysis.

    PubMed

    Cao, Yuanyuan; Wang, Zhen; Liao, Shenglong; Wang, Jian; Wang, Yapei

    2016-01-18

    The remote control of enzymatic catalysis is of significant importance in disease treatment and industrial applications. Herein, we designed a microheater composed of a porous polylactic acid (PLA) matrix and polydopamine (PDA) with notable photothermal conversion capability. Starch hydrolysis, catalyzed by using α-amylase, was accelerated in the presence of the microheater under illumination with near-infrared light or natural sunlight at room temperature. Additionally, the methodology was extended to the preparation of microwave-absorbing materials with the deposition of polyaniline on porous PLA matrix. The porous morphology improves the energy-conversion efficiency.

  19. Development of microheaters for gas sensor with an AT-Mega 8535 temperature controller using a PWM (pulse width modulation) method

    NASA Astrophysics Data System (ADS)

    Megayanti, Meti; Panatarani, Camellia; Joni, I. Made

    2016-03-01

    Microheater is the main component in gas sensor characterized by their sensitivity, selectivity, and time response of gas sensor which is depend on the microheater temperature stability. A Cu microheater was developed and utilized AT-Mega 8535 controller using a PWM (pulse width modulation) method. This control system is interfaced to the PC to observe the real time temperature response of the microheater. Three initial resistance (R0) variations of microheater were developed in an open loop control system. The power characteristic of designed microheater depends on the specified microheater initial resistance. The smaller R0, the less power required to reach a temperature setting value. The developed microheater was designed to reach a temperature setting value of 250°C having resistance 0.531 Ω for 1.979 Watt and 0.265 Ω for 1.072 Watt respectively. The results of the investigation on the control performances shows microheater-control system achieved operating temperature up to 250°C. The response of the temperature control shows smallest R0 resulted in a high stability with short settling time, short delay time and small ripple for temperature setting values higher than 150°C. The obtained error of microheater temperature with R0 = 0.265 is 8.596 %. It is concluded that the developed microheater can be utilized as a component of a gas sensor.

  20. Development and characterization of a microheater array device for real-time DNA mutation detection

    NASA Astrophysics Data System (ADS)

    Williams, Layne; Okandan, Murat; Chagovetz, Alex; Blair, Steve

    2008-02-01

    DNA analysis, specifically single nucleotide polymorphism (SNP) detection, is becoming increasingly important in rapid diagnostics and disease detection. Temperature is often controlled to help speed reaction rates and perform melting of hybridized oligonucleotides. The difference in melting temperatures, Tm, between wild-type and SNP sequences, respectively, to a given probe oligonucleotide, is indicative of the specificity of the reaction. We have characterized Tm's in solution and on a solid substrate of three sequences from known mutations associated with Cystic Fibrosis. Taking advantage of Tm differences, a microheater array device was designed to enable individual temperature control of up to 18 specific hybridization events. The device was fabricated at Sandia National Laboratories using surface micromachining techniques. The microheaters have been characterized using an IR camera at Sandia and show individual temperature control with minimal thermal cross talk. Development of the device as a real-time DNA detection platform, including surface chemistry and associated microfluidics, is described.

  1. Development and characterization of a microheater array device for real-time DNA mutation detection

    NASA Astrophysics Data System (ADS)

    Williams, Layne; Okandan, Murat; Chagovetz, Alex; Blair, Steve

    2008-04-01

    DNA analysis, specifically single nucleotide polymorphism (SNP) detection, is becoming increasingly important in rapid diagnostics and disease detection. Temperature is often controlled to help speed reaction rates and perform melting of hybridized oligonucleotides. The difference in melting temperatures, Tm, between wild-type and SNP sequences, respectively, to a given probe oligonucleotide, is indicative of the specificity of the reaction. We have characterized Tm's in solution and on a solid substrate of three sequences from known mutations associated with Cystic Fibrosis. Taking advantage of Tm differences, a microheater array device was designed to enable individual temperature control of up to 18 specific hybridization events. The device was fabricated at Sandia National Laboratories using surface micromachining techniques. The microheaters have been characterized using an IR camera at Sandia and show individual temperature control with minimal thermal cross talk. Development of the device as a real-time DNA detection platform, including surface chemistry and associated microfluidics, is described.

  2. Adaptive Optics Imaging in Laser Pointer Maculopathy.

    PubMed

    Sheyman, Alan T; Nesper, Peter L; Fawzi, Amani A; Jampol, Lee M

    2016-08-01

    The authors report multimodal imaging including adaptive optics scanning laser ophthalmoscopy (AOSLO) (Apaeros retinal image system AOSLO prototype; Boston Micromachines Corporation, Boston, MA) in a case of previously diagnosed unilateral acute idiopathic maculopathy (UAIM) that demonstrated features of laser pointer maculopathy. The authors also show the adaptive optics images of a laser pointer maculopathy case previously reported. A 15-year-old girl was referred for the evaluation of a maculopathy suspected to be UAIM. The authors reviewed the patient's history and obtained fluorescein angiography, autofluorescence, optical coherence tomography, infrared reflectance, and AOSLO. The time course of disease and clinical examination did not fit with UAIM, but the linear pattern of lesions was suspicious for self-inflicted laser pointer injury. This was confirmed on subsequent questioning of the patient. The presence of linear lesions in the macula that are best highlighted with multimodal imaging techniques should alert the physician to the possibility of laser pointer injury. AOSLO further characterizes photoreceptor damage in this condition. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:782-785.]. PMID:27548458

  3. Adaptive Optics Imaging in Laser Pointer Maculopathy.

    PubMed

    Sheyman, Alan T; Nesper, Peter L; Fawzi, Amani A; Jampol, Lee M

    2016-08-01

    The authors report multimodal imaging including adaptive optics scanning laser ophthalmoscopy (AOSLO) (Apaeros retinal image system AOSLO prototype; Boston Micromachines Corporation, Boston, MA) in a case of previously diagnosed unilateral acute idiopathic maculopathy (UAIM) that demonstrated features of laser pointer maculopathy. The authors also show the adaptive optics images of a laser pointer maculopathy case previously reported. A 15-year-old girl was referred for the evaluation of a maculopathy suspected to be UAIM. The authors reviewed the patient's history and obtained fluorescein angiography, autofluorescence, optical coherence tomography, infrared reflectance, and AOSLO. The time course of disease and clinical examination did not fit with UAIM, but the linear pattern of lesions was suspicious for self-inflicted laser pointer injury. This was confirmed on subsequent questioning of the patient. The presence of linear lesions in the macula that are best highlighted with multimodal imaging techniques should alert the physician to the possibility of laser pointer injury. AOSLO further characterizes photoreceptor damage in this condition. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:782-785.].

  4. Improved Selectivity and Sensitivity of Gas Sensing Using a 3D Reduced Graphene Oxide Hydrogel with an Integrated Microheater.

    PubMed

    Wu, Jin; Tao, Kai; Miao, Jianmin; Norford, Leslie K

    2015-12-16

    Low-cost, one-step, and hydrothermal synthesized 3D reduced graphene oxide hydrogel (RGOH) is exploited to fabricate a high performance NO2 and NH3 sensor with an integrated microheater. The sensor can experimentally detect NO2 and NH3 at low concentrations of 200 ppb and 20 ppm, respectively, at room temperature. In addition to accelerating the signal recovery rate by elevating the local silicon substrate temperature, the microheater is exploited for the first time to improve the selectivity of NO2 sensing. Specifically, the sensor response from NH3 can be effectively suppressed by a locally increased temperature, while the sensitivity of detecting NO2 is not significantly affected. This leads to good discrimination between NO2 and NH3. This strategy paves a new avenue to improve the selectivity of gas sensing by using the microheater to raise substrate temperature. PMID:26630364

  5. Microheater as an alternative to lasers for in-vitro fertilization applications

    NASA Astrophysics Data System (ADS)

    Palanker, Daniel V.; Turovets, Igor; Glazer, Rima; Reubinoff, Benjamin E.; Hilman, Dalia; Lewis, Aaron

    1999-06-01

    During the last decade various lasers have been applied to drilling of the micrometer-sized holes in the zona pellucida of oocytes for in-vitro fertilization applications. In this paper we describe an alternative approach to laser instrumentation based on microfabricated device capable of precise drilling of uniform holes in the zona pellucida of oocytes. This device consists of a thin (1 micrometer) film microheater built on the tip of glass capillary with a diameter varying between a few to a few tens of micrometers. Duration of the pulse of heat produced by this microheater determines the spatial confinement of the heat wave in the surrounding liquid medium. We have demonstrated that gradual microdrilling of the zona pellucida can be accomplished using a series of pulses with duration of about 300 microseconds when the microheater was held in contact with the zona pellucida. Pulse energy applied to 20 micrometer tip was about 4 (mu) J. In vitro development and hatching of 127 micromanipulated embryos was compared to 103 non-drilled control embryos. The technique was found to be highly efficient in creating round, uniform, well defined holes with a smooth wall surface, matching the size of the heating source. The architecture of the surrounding zona pellucida was unaffected by the drilling, as demonstrated by scanning electron microscopy. Micromanipulated embryos presented no signs of thermal damage under light microscopy. The rate of blastocyst formation and hatching was similar in the micromanipulated and control groups. Following further testing in animal models, this methodology may be used as a cost- effective alternative to laser-based instrumentation in clinical applications such as assisted hatching and embryo biopsy.

  6. Assessment of the risk from laser pointers

    NASA Astrophysics Data System (ADS)

    Moseley, Harry; Tulley, F. M.

    2001-01-01

    We have examined a number of laser pointers that have been removed form the possession of accused persons by police in Scotland. An analysis of the first 30 consecutive items has shown that 28 were Class 3B, with radiated power up to 9.3 mW. These are potentially hazardous if viewed directly. Transient exposure is unlikely to cause long-term damage but prolonged exposure may cause permanent retinal injury.

  7. Laser Pointers Can Cause Serious Eye Damage in Kids

    MedlinePlus

    ... page: https://medlineplus.gov/news/fullstory_160743.html Laser Pointers Can Cause Serious Eye Damage in Kids ... 1, 2016 THURSDAY, Sept. 1, 2016 (HealthDay News) -- Laser pointers may look harmless enough, but when children ...

  8. Optofluidic microvalve-on-a-chip with a surface plasmon-enhanced fiber optic microheater

    PubMed Central

    Zhang, Zhijian; Kusimo, Abisola; Yu, Miao

    2014-01-01

    We present an optofluidic microvalve utilizing an embedded, surface plasmon-enhanced fiber optic microheater. The fiber optic microheater is formed by depositing a titanium thin film on the roughened end-face of a silica optical fiber that serves as a waveguide to deliver laser light to the titanium film. The nanoscale roughness at the titanium-silica interface enables strong light absorption enhancement in the titanium film through excitation of localized surface plasmons as well as facilitates bubble nucleation. Our experimental results show that due to the unique design of the fiber optic heater, the threshold laser power required to generate a bubble is greatly reduced and the bubble growth rate is significantly increased. By using the microvalve, stable vapor bubble generation in the microchannel is demonstrated, which does not require complex optical focusing and alignment. The generated vapor bubble is shown to successfully block a liquid flow channel with a size of 125 μm × 125 μm and a flow rate of ∼10 μl/min at ∼120 mW laser power. PMID:25538813

  9. POINTER: Portable Intelligent Trainer for External Robotics

    NASA Technical Reports Server (NTRS)

    Kuiper, Hilbert; Rikken, Patrick J.

    1994-01-01

    Intelligent tutoring systems (ITS's) play an increasing role in training and education of people with different levels of skill and knowledge. As compared to conventional computer based training (CBT) an ITS provides more tailored instruction by trying to mimic the teaching behavior of a human instructor as much as possible and is therefore much more flexible. This paper starts with an introduction to ITS's, followed by the description of an ITS for training of an (astronaut) operator in monitoring and controlling robotic arm procedures. The robotic arm will be used for exchange of equipment between a space station and a space plane involving critical and accurate movements of the robotic arm. The ITS for this application, called Pointer, is developed by TNO Physics and Electronics Laboratory and is based upon an existing ITS that includes procedural training. Pointer has been developed on a workstation whereas the target platform was a portable computer. Therefore, a lot of attention had to be paid to scaling effects and keeping up with user friendliness of the much smaller user interface. Although the learning domain was the control of a robotic arm, it is clear that use of intelligent training technologies on a portable computer has many other applications (payload operations, operation control rooms, etc.). Training can occur at any time and place in an attractive and cost effective way.

  10. Bacterial detection using a carbon nanotube gas sensor coupled with a microheater for ammonia synthesis by aerobic oxidisation of organic components.

    PubMed

    Suehiro, J; Ikeda, N; Ohtsubo, A; Imasaka, K

    2009-06-01

    In this study, the authors propose a new bacteria detection method using a carbon nanotube (CNT) gas sensor and a microheater, which were coupled into a Bio-MEMS (microelectromechanical systems)-type device. Bacteria were heated by the microheater in air so that ammonia (NH(3)) gas can be generated by the oxidation reaction of organic components of bacteria. Thus generated NH(3) gas was detected by using the CNT gas sensor, which was fabricated by dielectrophoresis (DEP) and combined with the microheater to form a small chamber. Cyclic pulsed heating operation was employed so that the CNT response to elevated temperature did not mask NH(3) response. It was demonstrated that the proposed device could detect and quantify 10(7) bacteria cells (Escherichia coli). Possible application of DEP to trap and enrich target bacteria on the microheater was also discussed.

  11. Advanced Reference Counting Pointers for Better Performance

    NASA Technical Reports Server (NTRS)

    Reinholtz, William

    2007-01-01

    A computer program implements reference counting pointers (RCPs) that are lock-free, thread-safe, async-safe, and operational on a multiprocessor computer. RCPs are powerful and convenient means of managing heap memory in C++ software. Most prior RCP programs use locks to ensure thread safety and manage concurrency. The present program was developed in a continuing effort to explore ways of using the C++ programming language to develop safety-critical and mission- critical software. This effort includes exploration of lock-free algorithms because they offer potential to avoid some costly and difficult verification problems. Unlike previously published RCP software, the present program does not use locks (meaning that no thread can block progress on another thread): Instead, this program implements algorithms that exploit capabilities of central-processing- unit hardware so as to avoid locks. Once locks are eliminated, it becomes possible to realize the other attributes mentioned in the first sentence. In addition to the abovementioned attributes, this program offers several advantages over other RCP programs that use locks: It is smaller (and, hence, is faster and uses less memory), it is immune to priority inversion, and there is no way for it to cause a C++ exception.

  12. X-Ray Diffraction Simulation Using Laser Pointers and Printers.

    ERIC Educational Resources Information Center

    Johnson, Neil E.

    2001-01-01

    Uses a laser pointer to demonstrate the analogy between optical and X-ray diffraction and a laser printer with 600 or 1200 dot resolution to create and modify arrays, print them on transparencies, and illuminate them with laser pointers. Includes 14 references. (Author/YDS)

  13. Advantages of nonclassical pointer states in postselected weak measurements

    NASA Astrophysics Data System (ADS)

    Turek, Yusuf; Maimaiti, W.; Shikano, Yutaka; Sun, Chang-Pu; Al-Amri, M.

    2015-08-01

    We investigate, within the weak measurement theory, the advantages of nonclassical pointer states over semiclassical ones for coherent, squeezed vacuum, and Schrödinger cat states. These states are utilized as pointer states for the system operator A ̂ with property Â2=I ̂ , where I ̂ represents the identity operator. We calculate the ratio between the signal-to-noise ratio of nonpostselected and postselected weak measurements. The latter is used to find the quantum Fisher information for the above pointer states. The average shifts for those pointer states with arbitrary interaction strength are investigated in detail. One key result is that we find the postselected weak measurement scheme for nonclassical pointer states to be superior to semiclassical ones. This can improve the precision of the measurement process.

  14. Proving Correctness for Pointer Programs in a Verifying Compiler

    NASA Technical Reports Server (NTRS)

    Kulczycki, Gregory; Singh, Amrinder

    2008-01-01

    This research describes a component-based approach to proving the correctness of programs involving pointer behavior. The approach supports modular reasoning and is designed to be used within the larger context of a verifying compiler. The approach consists of two parts. When a system component requires the direct manipulation of pointer operations in its implementation, we implement it using a built-in component specifically designed to capture the functional and performance behavior of pointers. When a system component requires pointer behavior via a linked data structure, we ensure that the complexities of the pointer operations are encapsulated within the data structure and are hidden to the client component. In this way, programs that rely on pointers can be verified modularly, without requiring special rules for pointers. The ultimate objective of a verifying compiler is to prove-with as little human intervention as possible-that proposed program code is correct with respect to a full behavioral specification. Full verification for software is especially important for an agency like NASA that is routinely involved in the development of mission critical systems.

  15. Thermopower measurements of atomic and molecular junctions using microheater-embedded mechanically-controllable break junctions

    NASA Astrophysics Data System (ADS)

    Tsutsui, Makusu; Morikawa, Takanori; Arima, Akihide; Taniguchi, Masateru

    2015-03-01

    There has been growing interest in developing high-performance thermoelectric materials for realizing thermoelectric power generation. Quantum confinement effects in low-dimensional structures are expected to provide high electronic density of states for enhanced thermopower, and thus considered as a promising approach for achieving a high figure of merit (M. S. Dresselhaus et al., Adv. Mat. 19 (2007) 1043-1053). From this respect, it is interesting to study thermoelectric properties of atomic and molecular junctions and evaluate their potential as a thermoelectric material. Recently, we have developed a heater-embedded micro-fabricated mechanically-controllable break junction (MCBJ) for investigating the thermoelectric transport in single-atom and -molecule junctions. Using the MCBJ devices, we could repeatedly form stable junctions at room temperatures via a self-breaking mechanism with one side being heated by the adjacent microheater. In my presentation, I will show the results of simultaneous measurements of the thermoelectric voltage and the electrical conductance of atom-sized Au junctions and Au-benzenedithiol-Au junctions and discuss on the geometrical dependence of thermoelectric transport.

  16. Two theories of consciousness: Semantic pointer competition vs. information integration.

    PubMed

    Thagard, Paul; Stewart, Terrence C

    2014-11-01

    Consciousness results from three mechanisms: representation by firing patterns in neural populations, binding of representations into more complex representations called semantic pointers, and competition among semantic pointers to capture the most important aspects of an organism's current state. We contrast the semantic pointer competition (SPC) theory of consciousness with the hypothesis that consciousness is the capacity of a system to integrate information (IIT). We describe computer simulations to show that SPC surpasses IIT in providing better explanations of key aspects of consciousness: qualitative features, onset and cessation, shifts in experiences, differences in kinds across different organisms, unity and diversity, and storage and retrieval.

  17. Weak measurements with orbital-angular-momentum pointer states.

    PubMed

    Puentes, G; Hermosa, N; Torres, J P

    2012-07-27

    Weak measurements are a unique tool for accessing information about weakly interacting quantum systems with minimal back action. Joint weak measurements of single-particle operators with pointer states characterized by a two-dimensional Gaussian distribution can provide, in turn, key information about quantum correlations that can be relevant for quantum information applications. Here we demonstrate that by employing two-dimensional pointer states endowed with orbital angular momentum (OAM), it is possible to extract weak values of the higher order moments of single-particle operators, an inaccessible quantity with Gaussian pointer states only. We provide a specific example that illustrates the advantages of our method both in terms of signal enhancement and information retrieval.

  18. Weak measurements with orbital-angular-momentum pointer states.

    PubMed

    Puentes, G; Hermosa, N; Torres, J P

    2012-07-27

    Weak measurements are a unique tool for accessing information about weakly interacting quantum systems with minimal back action. Joint weak measurements of single-particle operators with pointer states characterized by a two-dimensional Gaussian distribution can provide, in turn, key information about quantum correlations that can be relevant for quantum information applications. Here we demonstrate that by employing two-dimensional pointer states endowed with orbital angular momentum (OAM), it is possible to extract weak values of the higher order moments of single-particle operators, an inaccessible quantity with Gaussian pointer states only. We provide a specific example that illustrates the advantages of our method both in terms of signal enhancement and information retrieval. PMID:23006067

  19. Activities Using Headsticks and Optical Pointers: A Description of Methods.

    ERIC Educational Resources Information Center

    Eriksson, Britt-Marie; And Others

    A variety of head-mounted aids have been developed in the past decade to fill in the functional gaps of children and adults unable to use their hands at standard capacity. For those with speech difficulties, the optical pointer, headstick and mouthstick also provide communication alternatives. This handbook discusses the characteristics of several…

  20. [Laser pointers are not toys; eye injury with permanent loss of visual acuity].

    PubMed

    Keunen, Jan E E; Delbecq, Ann-Laure M H; Cruysberg, J R M Hans; van Meurs, Jan C; Gan, Ivan M; Berendschot, Tos T J M

    2014-01-01

    In the nineteen-nineties, there was much hype in the European media about presumed laser pointer maculopathy. However, the recent introduction of more powerful and therefore more dangerous laser pointers and their easy availability on the internet necessitates vigilance on the issue. This is an urgent matter, as here we report three cases of proven maculopathy due to an unsafe laser pointer. Three boys aged 13, 9 and 12 years used an unsafe laser pointer as a toy and looked repeatedly into the pointer, resulting in a permanent reduction in visual acuity due to macular damage. Laser pointers are not designed to be children's toys or instruments to annoy people in a crowd. Health authorities and the ophthalmic community should be aware of the potential danger of improper use of high-output laser pointers and warn the general public before the widespread availability of unsafe laser pointers and consequently laser pointer-induced macular damage becomes a true social problem.

  1. Evaluation of a green laser pointer for flow cytometry.

    PubMed

    Habbersett, Robert C; Naivar, Mark A; Woods, Travis A; Goddard, Gregory R; Graves, Steven W

    2007-10-01

    Flow cytometers typically incorporate expensive lasers with high-quality (TEM00) output beam structure and very stable output power, significantly increasing system cost and power requirements. Red diode lasers minimize power consumption and cost, but limit fluorophore selection. Low-cost DPSS laser pointer modules could possibly offer increased wavelength selection but presumed emission instability has limited their use. A $160 DPSS 532 nm laser pointer module was first evaluated for noise characteristics and then used as the excitation light source in a custom-built flow cytometer for the analysis of fluorescent calibration and alignment microspheres. Eight of ten modules tested were very quiet (RMS noise < or = 0.6% between 0 and 5 MHz). With a quiet laser pointer module as the light source in a slow-flow system, fluorescence measurements from alignment microspheres produced CVs of about 3.3%. Furthermore, the use of extended transit times and < or =1 mW of laser power produced both baseline resolution of all 8 peaks in a set of Rainbow microspheres, and a detection limit of <20 phycoerythrin molecules per particle. Data collected with the transit time reduced to 25 micros (in the same instrument but at 2.4 mW laser output) demonstrated a detection limit of approximately 75 phycoerythrin molecules and CVs of about 2.7%. The performance, cost, size, and power consumption of the tested laser pointer module suggests that it may be suitable for use in conventional flow cytometry, particularly if it were coupled with cytometers that support extended transit times. PMID:17712796

  2. Coupling-deformed pointer observables and weak values

    NASA Astrophysics Data System (ADS)

    Zhang, Yu-Xiang; Wu, Shengjun; Chen, Zeng-Bing

    2016-03-01

    While the novel applications of weak values have recently attracted wide attention, weak measurement, the usual way to extract weak values, suffers from risky approximations and severe quantum noises. In this paper, we show that the weak-value information can be obtained exactly in strong measurement with postselections, via measuring the coupling-deformed pointer observables, i.e., the observables selected according to the coupling strength. With this approach, we keep all the advantages claimed by weak-measurement schemes and at the same time solve some widely criticized problems thereof, such as the questionable universality, systematical bias, and drastic inefficiency.

  3. Predictability sieve, pointer states, and the classicality of quantum trajectories

    SciTech Connect

    Dalvit, D. A. R.; Zurek, W. H.; Dziarmaga, J.

    2005-12-15

    We study various measures of classicality of the states of open quantum systems subject to decoherence. Classical states are expected to be stable in spite of decoherence, and are thought to leave conspicuous imprints on the environment. Here these expected features of environment-induced superselection are quantified using four different criteria: predictability sieve (which selects states that produce least entropy), purification time (which looks for states that are the easiest to find out from the imprint they leave on the environment), efficiency threshold (which finds states that can be deduced from measurements on a smallest fraction of the environment), and purity loss time (that looks for states for which it takes the longest to lose a set fraction of their initial purity). We show that when pointer states--the most predictable states of an open quantum system selected by the predictability sieve--are well defined, all four criteria agree that they are indeed the most classical states. We illustrate this with two examples: an underdamped harmonic oscillator, for which coherent states are unanimously chosen by all criteria, and a free particle undergoing quantum Brownian motion, for which most criteria select almost identical Gaussian states (although, in this case, the predictability sieve does not select well defined pointer states)

  4. Microheater-integrated silicon coupled photonic crystal microcavities for low-power thermo-optic switching over a wide spectrum

    NASA Astrophysics Data System (ADS)

    Zhang, Xingyu; Chakravarty, Swapnajit; Chung, Chi-Jui; Pan, Zeyu; Yan, Hai; Chen, Ray T.

    2016-03-01

    We design, fabricate and experimentally demonstrate a compact thermo-optic gate switch comprising a 3.78μm-long coupled L0-type photonic crystal microcavities on a silicon-on-insulator substrate. A nanohole is inserted in the center of each individual L0 photonic crystal microcavity. Coupling between identical microcavities gives rise to bonding and antibonding states of the coupled photonic molecules. The coupled photonic crystal microcavities are numerically simulated and experimentally verified with a 6nm-wide flat-bottom resonance in its transmission spectrum, which enables wider operational spectrum range than microring resonators. An integrated micro-heater is in direct contact with the silicon core to efficiently drive the device. The thermo-optic switch is measured with an optical extinction ratio of 20dB, an on-off switching power of 18.2mW, a therm-optic tuning efficiency of 0.63nm/mW, a rise time of 14.8μsec and a fall time of 18.5μsec. The measured on-chip loss on the transmission band is as low as 1dB.

  5. Fast-Response, Sensitivitive and Low-Powered Chemosensors by Fusing Nanostructured Porous Thin Film and IDEs-Microheater Chip

    PubMed Central

    Dai, Zhengfei; Xu, Lei; Duan, Guotao; Li, Tie; Zhang, Hongwen; Li, Yue; Wang, Yi; Wang, Yuelin; Cai, Weiping

    2013-01-01

    The chemiresistive thin film gas sensors with fast response, high sensitivity, low power consumption and mass-produced potency, have been expected for practical application. It requires both sensitive materials, especially exquisite nanomaterials, and efficient substrate chip for heating and electrical addressing. However, it is challenging to achieve repeatable microstructures across the films and low power consumption of substrate chip. Here we presented a new sensor structure via the fusion of metal-oxide nanoporous films and micro-electro-mechanical systems (MEMS)-based sensing chip. An interdigital-electrodes (IDEs) and microheater integrated MEMS structure is designed and employed as substrate chip to in-situ fabricate colloidal monolayer template-induced metal-oxide (egg. SnO2) nanoporous sensing films. This fused sensor demonstrates mW-level low power, ultrafast response (~1 s), and parts-per-billion lever detection for ethanol gas. Due to the controllable template strategy and mass-production potential, such micro/nano fused high-performance gas sensors will be next-generation key miniaturized/integrated devices for advanced practical applications. PMID:23591580

  6. Designing Light Beam Transmittance Measuring Tool Using a Laser Pointer

    NASA Astrophysics Data System (ADS)

    Nuroso, H.; Kurniawan, W.; Marwoto, P.

    2016-08-01

    A simple instrument used for measuring light beam transmittance percentage made of window film has been developed. The instrument uses a laser pointer of 405 nm and 650 nm ±10% as a light source. Its accuracy approaches 80%. Transmittance data was found by comparing the light beam before and after passing the window film. The light intensity measuring unit was deleted by splitting the light source into two beams through a beam splitter. The light beam was changed into resistance by a NORP12 LDR sensor designed at a circuit of voltage divider rule of Khirchoff's laws. This conversion system will produce light beam intensity received by the sensor to become an equal voltage. This voltage will, then, be presented on the computer screen in the form of a real time graph via a 2.0 USB data transfer.

  7. Direct state reconstruction with coupling-deformed pointer observables

    NASA Astrophysics Data System (ADS)

    Zhu, Xuanmin; Zhang, Yu-Xiang; Wu, Shengjun

    2016-06-01

    Direct state tomography (DST) using weak measurements has received wide attention. Based on the concept of coupling-deformed pointer observables presented by Zhang et al. [Y.-X. Zhang, S. Wu, and Z.-B. Chen, Phys. Rev. A 93, 032128 (2016), 10.1103/PhysRevA.93.032128], a modified direct state tomography (MDST) is proposed, examined, and compared with other typical state tomography schemes. MDST has exact validity for measurements of any strength. We identify the strength needed to attain the highest efficiency level of MDST by using statistical theory. MDST is much more efficient than DST in the sense that far fewer samples are needed to reach DST's level of reconstruction accuracy. Moreover, MDST has no inherent bias when compared to DST.

  8. 'Einselection' of pointer observables: The new H-theorem?

    NASA Astrophysics Data System (ADS)

    Kastner, Ruth E.

    2014-11-01

    In attempting to derive irreversible macroscopic thermodynamics from reversible microscopic dynamics, Boltzmann inadvertently smuggled in a premise that assumed the very irreversibility he was trying to prove: 'molecular chaos'. The program of 'einselection' (environmentally induced superselection) within Everettian approaches faces a similar 'Loschmidt's Paradox': the universe, according to the Everettian picture, is a closed system obeying only unitary dynamics, and it therefore contains no distinguishable environmental subsystems with the necessary 'phase randomness' to effect einselection of a pointer observable. The theoretically unjustified assumption of distinguishable environmental subsystems is the hidden premise that makes the derivation of einselection circular. In effect, it presupposes the 'emergent' structures from the beginning. Thus the problem of basis ambiguity remains unsolved in Everettian interpretations.

  9. A Scalable Nonuniform Pointer Analysis for Embedded Program

    NASA Technical Reports Server (NTRS)

    Venet, Arnaud

    2004-01-01

    In this paper we present a scalable pointer analysis for embedded applications that is able to distinguish between instances of recursively defined data structures and elements of arrays. The main contribution consists of an efficient yet precise algorithm that can handle multithreaded programs. We first perform an inexpensive flow-sensitive analysis of each function in the program that generates semantic equations describing the effect of the function on the memory graph. These equations bear numerical constraints that describe nonuniform points-to relationships. We then iteratively solve these equations in order to obtain an abstract storage graph that describes the shape of data structures at every point of the program for all possible thread interleavings. We bring experimental evidence that this approach is tractable and precise for real-size embedded applications.

  10. Induced immobility in nervous and normal Pointer dogs.

    PubMed

    Reese, W G; Newton, J E; Angel, C

    1982-10-01

    Pointer dogs learn complex hunting tasks such as vigorous aim-directed activity in tracking specific birds and sudden rigid immobility "on point" at appropriate distance from the prey. In the presence of a human, dogs of the Arkansas Line of Nervous Pointers show markedly reduced activity. In close quarters, where they cannot flee, they usually react to humans by freezing. These responses do not extinguish. The breed demonstrates a strong capacity to inhibit motion. In our nervous dogs, this trait is greatly exaggerated. In the search for an objective and rapidly modifiable target motor sign to correlate with biochemical and pharmacological events, we discovered that 10 of 10 nervous dogs, in contrast to kennel mates of a normal line, developed tonic immobility (TI) which was induced by manual inversion into a sling and stroking. This is the first systematic demonstration of TI in mature dogs. The TI was accompanied by reduced telemetered heart rate (HR) compared to baseline. Release from the inverted position was accompanied by marked HR increase. In the absence of humans, both before and after the inversion, all nervous dogs showed little or no movement about the testing area. This was in contrast to the nine normal line dogs, which were comparable in age and sex. These normal dogs were very active before and after inversion into the sling. Five of the normals remained in the sling but did not show head and neck immobility and were generally relaxed. Their HRs increased slightly while in the inverted position, thereafter returning to baseline. The four normals which righted themselves soon after the inversion showed reduced HR with the resumed activity. We discuss possible mechanisms and review some of the implications for psychiatry and behavioral biology. PMID:7202039

  11. SSRPT (SSR Pointer Trackeer) for Cassini Mission Operations - A Ground Data Analysis Tool

    NASA Technical Reports Server (NTRS)

    Kan, E.

    1998-01-01

    Tracking the resources of the two redundant Solid State Recorders (SSR) is a necessary routine for Cassini spacecraft mission operations. Instead of relying on a full-fledged spacecraft hardware/software simulator to track and predict the SSR recording and playback pointer positions, a stand-alone SSR Pointer Tracker tool was developed as part of JPL's Multimission Spacecraft Analysis system.

  12. Retinal damage induced by mirror-reflected light from a laser pointer.

    PubMed

    Thanos, Solon; Böhm, Michael R R; Meyer zu Hörste, Melissa; Schmidt, Peter-Fritz

    2015-10-05

    The safety of laser pointers is a major public health issue since class I and II laser pointers are available worldwide and used as toys by children despite several reports cautioning such use. Here we present the first case of retinal injury caused by the laser beam of a toy laser pointer operated by a school boy and directed via the rear-view mirror of a bus into the eye of the driver. This case emphasises the great importance of cautious and appropriate use of low-energy laser pointers. Laser pointers of any class should not be made available to children because they are unlikely to understand the risks of such lasers when using them in play.

  13. An automatic recognition method of pointer instrument based on improved Hough transform

    NASA Astrophysics Data System (ADS)

    Xu, Li; Fang, Tian; Gao, Xiaoyu

    2015-10-01

    For the automatic recognition of pointer instrument, the method for the automatic recognition of pointer instrument based on improved Hough Transform was proposed in this paper. The automatic recognition of pointer instrument is applied to all kinds of lighting conditions, but the accuracy of it binaryzation will be influenced when the light is too strong or too dark. Therefore, the improved Ostu method was suggested to realize recognition for adaptive thresholding of pointer instrument under all kinds of lighting conditions. On the basis of dial image characteristics, Otsu method is used to get the value of maximum between-cluster variance and initial threshold than analyze its maximum between-cluster variance value to determine the light and shade of the image. When the images are too bright or too dark, the smaller pixels should be given up and then calculate the initial threshold by Otsu method again and again until the best binaryzation image was obtained. Hence, transform the pointer straight line of the binaryzation image to Hough parameter space through improved Hough Transform to determine the position of the pointer straight line by searching the maximum value of arrays of the same angle. Finally, according to angle method, the pointer reading was obtained by the linear relationship for the initial scale and angle of the pointer instrument. Results show that the improved Otsu method make pointer instrument possible to obtained the accuracy binaryzation image even though the light is too bright or too dark , which improves the adaptability of pointer instrument to automatic recognize the light under different conditions. For the pressure gauges with range of 60MPa, the relative error identification reached to 0.005 when use the improved Hough Transform Algorithm.

  14. Demonstration of a Balloon Borne Arc-Second Pointer Design

    NASA Technical Reports Server (NTRS)

    DeWeese, Keith D.; Ward, Philip R.

    2006-01-01

    Many designs for utilizing stratospheric balloons as low-cost platforms on which to conduct space science experiments have been proposed throughout the years. A major hurdle in extending the range of experiments for which these vehicles are useful has been the imposition of the gondola dynamics on the accuracy with which an instrument can be kept pointed at a celestial target. A significant number of scientists have sought the ability to point their instruments with jitter in the arc-second range. This paper presents the design and analysis of a stratospheric balloon borne pointing system that is able to meet this requirement. The test results of a demonstration prototype of the design with similar ability are also presented. Discussion of a high fidelity controller simulation for design analysis is presented. The flexibility of the flight train is represented through generalized modal analysis. A multiple controller scheme is utilized for coarse and fine pointing. Coarse azimuth pointing is accomplished by an established pointing system, with extensive flight history, residing above the gondola structure. A pitch-yaw gimbal mount is used for fine pointing, providing orthogonal axes when nominally on target. Fine pointing actuation is from direct drive dc motors, eliminating backlash problems. An analysis of friction nonlinearities and a demonstration of the necessity in eliminating static friction are provided. A unique bearing hub design is introduced that eliminates static friction from the system dynamics. A control scheme involving linear accelerometers for enhanced disturbance rejection is also presented. Results from a linear analysis of the total system and the high fidelity simulation are given. Results from a generalized demonstration prototype are presented. Commercial off-the-shelf (COTS) hardware was used to demonstrate the efficacy and performance of the pointer design for a mock instrument. Sub-arcsecond pointing ability from a ground hang test setup

  15. Coupling-induced bipartite pointer states in arrays of electron billiards: quantum Darwinism in action?

    PubMed

    Brunner, R; Akis, R; Ferry, D K; Kuchar, F; Meisels, R

    2008-07-11

    We discuss a quantum system coupled to the environment, composed of an open array of billiards (dots) in series. Beside pointer states occurring in individual dots, we observe sets of robust states which arise only in the array. We define these new states as bipartite pointer states, since they cannot be described in terms of simple linear combinations of robust single-dot states. The classical existence of bipartite pointer states is confirmed by comparing the quantum-mechanical and classical results. The ability of the robust states to create "offspring" indicates that quantum Darwinism is in action.

  16. Coupling-Induced Bipartite Pointer States in Arrays of Electron Billiards: Quantum Darwinism in Action?

    NASA Astrophysics Data System (ADS)

    Brunner, R.; Akis, R.; Ferry, D. K.; Kuchar, F.; Meisels, R.

    2008-07-01

    We discuss a quantum system coupled to the environment, composed of an open array of billiards (dots) in series. Beside pointer states occurring in individual dots, we observe sets of robust states which arise only in the array. We define these new states as bipartite pointer states, since they cannot be described in terms of simple linear combinations of robust single-dot states. The classical existence of bipartite pointer states is confirmed by comparing the quantum-mechanical and classical results. The ability of the robust states to create “offspring” indicates that quantum Darwinism is in action.

  17. Precise Interprocedural Analysis in the Presence of Pointers to the Stack

    NASA Astrophysics Data System (ADS)

    Sotin, Pascal; Jeannet, Bertrand

    In a language with procedures calls and pointers as parameters, an instruction can modify memory locations anywhere in the call-stack. The presence of such side effects breaks most generic interprocedural analysis methods, which assume that only the top of the stack may be modified. We present a method that addresses this issue, based on the definition of an equivalent local semantics in which writing through pointers has a local effect on the stack. Our second contribution in this context is an adequate representation of summary functions that models the effect of a procedure, not only on the values of its scalar and pointer variables, but also on the values contained in pointed memory locations. Our implementation in the interprocedural analyser PInterproc results in a verification tool that infers relational properties on the value of Boolean, numerical and pointer variables.

  18. The Measurement of the Speed of Light Using a Laser Pointer.

    ERIC Educational Resources Information Center

    Mak, Se-yuen; Yip, Din-yan

    2000-01-01

    Presents a method for measuring the speed of light using a laser pointer with adjustable focus as the signal carrier, a signal generator to modulate the light beam, and a student oscilloscope to detect the phase shift. (Author/CCM)

  19. Retinal Damage from Laser Pointer Misuse – Case Series from the Military Sector in Oman

    PubMed Central

    Shenoy, Radha; Bialasiewicz, Alexander A; Bandara, Asoka; Isaac, Roshini

    2015-01-01

    Laser pointers are practical and safe training tools when used properly. If used incorrectly they can cause ocular damage, potentially resulting in devastating vision loss. The ocular and visual morbidity can result in significant expenses for medical care and inability to work (temporarily or permanently) for civilians and military personnel. We present three cases of soldiers who experienced vision loss following exposure to laser pointers, while celebrating successfull football game. PMID:26180486

  20. Arc-Second Pointer for Balloon-Borne Astronomical Instrument

    NASA Technical Reports Server (NTRS)

    Ward, Philip R.; DeWeese, Keith

    2004-01-01

    A control system has been designed to keep a balloon-borne scientific instrument pointed toward a celestial object within an angular error of the order of an arc second. The design is intended to be adaptable to a large range of instrument payloads. The initial payload to which the design nominally applies is considered to be a telescope, modeled as a simple thin-walled cylinder 24 ft (approx.= 7.3 m) long, 3 ft (approx.= 0.91 m) in diameter, weighing 1,500 lb (having a mass of .680 kg). The instrument would be mounted on a set of motor-driven gimbals in pitch-yaw configuration. The motors on the gimbals would apply the control torques needed for fine adjustments of the instrument in pitch and yaw. The pitch-yaw mount would, in turn, be suspended from a motor mount at the lower end of a pair of cables hanging down from the balloon (see figure). The motor in this mount would be used to effect coarse azimuth control of the pitch-yaw mount. A notable innovation incorporated in the design is a provision for keeping the gimbal bearings in constant motion. This innovation would eliminate the deleterious effects of static friction . something that must be done in order to achieve the desired arc-second precision. Another notable innovation is the use of linear accelerometers to provide feedback that would facilitate the early detection and counteraction of disturbance torques before they could integrate into significant angular-velocity and angular-position errors. The control software processing the sensor data would be capable of distinguishing between translational and rotational accelerations. The output of the accelerometers is combined with that of angular position and angular-velocity sensors into a proportional + integral + derivative + acceleration control law for the pitch and yaw torque motors. Preliminary calculations have shown that with appropriate gains, the power demand of the control system would be low enough to be satisfiable by means of storage

  1. Photoblepharokeratoconjunctivitis caused by invisible infrared radiation emitted from a green laser pointer.

    PubMed

    Khedr, Yahya A H; Khedr, Abdulla H

    2014-01-01

    There are a wide variety of laser pointers sold to the general public. Among those are the high-powered diode-pumped solid-state lasers (>5 mW), which do not follow the laser safety regulations for packing, and are sold as regular lasers without the infrared (IR) filters. In this case report, we encountered a patient with photoblepharokeratoconjunctivitis caused by the invisible IR radiations emitted from a green laser pointer. Owing to the thermal effect of the invisible IR rays led to the disease. PMID:24618868

  2. Capillary-driven microfluidic chips with evaporation-induced flow control and dielectrophoretic microbead trapping

    NASA Astrophysics Data System (ADS)

    Temiz, Yuksel; Skorucak, Jelena; Delamarche, Emmanuel

    2014-03-01

    This work reports our efforts on developing simple-to-use microfluidic devices for point-of-care diagnostic applications with recent extensions that include the trapping of microbeads using dielectrophoresis (DEP) and the modulation of capillary-driven flow using integrated microheaters. DEP serves the purpose of trapping microbeads coated with receptors and analytes for detection of a fluorescent signal. The microheater is actuated once the chip is filled by capillarity, creating an evaporation-induced flow tuned according to assay conditions. The chips are composed of a glass substrate patterned with 50-nm-thick Pd electrodes and microfluidic structures made using a 20-μm-thick dry-film resist (DFR). Chips are covered/sealed by low-temperature (50 °C) lamination of a 50-μm-thick DFR layer having excellent optical and mechanical properties. To separate cleaned and sealed chips from the wafer, we used an effective chip singulation technique that we informally call the "chip-olate" process. In the experimental section, we first studied dielectrophoretic trapping of 10 μm beads for flow rates ranging from 80 pL s-1 to 2.5 nL s-1 and that are generated by an external syringe pump. Then, we characterized the embedded microheater in DFR-covered chips. Flow rates as high as 8 nL s-1 were generated by evaporation-induced flow when the heater was biased by 10 V, corresponding to 270 mW power. Finally, DEP-based trapping and fluorescent detection of functionalized beads were demonstrated as the flow was generated by the combination of capillary filling and evaporation-induced flow.

  3. The Trainee Teacher and His Practice Class. Fifty Pointers for the Student-Teacher.

    ERIC Educational Resources Information Center

    Rees, Alun L. W.

    1969-01-01

    This handbook, based on the author's experience of supervising the English practice-classes of trainee teachers, was originally compiled for the specific use of students at the National University of Trujillo, Peru, and consists of a list of pointers embracing the most prevalent of trainees' shortcomings observed over a period of years at all…

  4. Pointer Animation Implementation at Development of Multimedia Learning of Java Programming

    ERIC Educational Resources Information Center

    Rusli, Muhammad; Atmojo, Yohanes Priyo

    2015-01-01

    This research represents the development research using the references of previous research results related to the development of interactive multimedia learning (learner controlled), specially about the effectiveness and efficiency of multimedia learning of a content that developed by pointer animation implementation showing the content in…

  5. A Laser-Pointer-Based Spectrometer for Endpoint Detection of EDTA Titrations

    ERIC Educational Resources Information Center

    Dahm, Christopher E.; Hall, James W.; Mattioni, Brian E.

    2004-01-01

    A laser spectrometer for the ethylenediaminetetra-acetic acid (EDTA) titration of magnesium or calcium ions that is designed around a handheld laser pointer as the source and a photoresistor as the detector is developed. Findings show that the use of the spectrometer reduces the degree of uncertainty and error in one part of the EDTA titrations,…

  6. Monitoring of quantum mode correlation functions in the presence of pointer state phase relaxation

    NASA Astrophysics Data System (ADS)

    Trifanova, E.; Trifanov, A.

    2016-08-01

    In present work we investigate the process of interaction between two-level atom- pointer and cavity mode to obtain correlation functions of mode quantum state. In particular, we analyze the protocol of indirect photodetection which allow estimations for average values of photon number operator in any order using statistics of atom state detector clicks.

  7. Laser-Induced Fluorescence in Gaseous [I[subscript]2] Excited with a Green Laser Pointer

    ERIC Educational Resources Information Center

    Tellinghuisen, Joel

    2007-01-01

    A green laser pointer could be used in a flashy demonstration of laser-induced fluorescence in the gas phase by directing the beam of the laser through a cell containing [I[subscript]2] at its room temperature vapor pressure. The experiment could be used to provide valuable insight into the requirements for laser-induced fluorescence (LIF) and the…

  8. Laser Pointers: Low-Cost, Low-Tech Innovative, Interactive Instruction Tool

    ERIC Educational Resources Information Center

    Zdravkovska, Nevenka; Cech, Maureen; Beygo, Pinar; Kackley, Bob

    2010-01-01

    This paper discusses the use of laser pointers at the Engineering and Physical Sciences Library, University of Maryland, College Park, as a personal response system (PRS) tool to encourage student engagement in and interactivity with one-shot, lecture-based information literacy sessions. Unlike more sophisticated personal response systems like…

  9. Using Local Perturbations To Manipulate and Control Pointer States in Quantum Dot Systems

    NASA Astrophysics Data System (ADS)

    Akis, Richard; Speyer, Gil; Ferry, David; Brunner, Roland

    2012-02-01

    Recently, scanning gate microscopy (SGM) was used to image scarred wave functions in an open InAs quantum dot[1]. The SGM tip provides a local potential perturbation and imaging is performed by measuring changes in conductance. Scarred wave functions, long associated with quantum chaos, have been shown in open dots to correspond to pointer states[2], eigenstates that survive the decoherence process that occurs via coupling to the environment. Pointer states modulate the conductance, yielding periodic fluctuations and the scars, normally thought unstable, are stabilized by quantum Darwinism [3]. We shall show that, beyond probing, pointer states can be manipulated by local perturbations. Particularly interesting effects occur in coupled quantum dot arrays, where a pointer state localized in one dot can be shifted over into another with a perturbation in a completely different part of the system. These nonlocal effects may perhaps be exploited to give such systems an exotic functionality. [1] A. M. Burke, R. Akis, T. E. Day, Gil Speyer, D. K. Ferry, and B. R. Bennett, Phys. Rev. Lett. 104, 176801 (2010). [2] D. K. Ferry, R. Akis, and J. P. Bird, Phys. Rev. Lett. 104, 176801 (2004). [3] R. Brunner, R. Akis,D. K. Ferry, F. Kuchar,and R. Meisels, Phys. Rev. Lett. 101, 024102 (2008).

  10. Sport Instruction for Individuals with Disabilities. The Best of Practical Pointers.

    ERIC Educational Resources Information Center

    American Alliance for Health, Physical Education, Recreation and Dance, Reston, VA.

    This book, written for teachers by teachers, includes articles by 14 contributing authors and is divided into three sections. Section 1 is entitled "Practical Pointers for Team Sports" and contains the following chapters: "Mainstreaming the Physically Handicapped for Team Sports" (S. J. Grosse); "Program Guide to Team Soccer for the Mentally…

  11. VIEWCACHE: An incremental pointer-based access method for autonomous interoperable databases

    NASA Technical Reports Server (NTRS)

    Roussopoulos, N.; Sellis, Timos

    1992-01-01

    One of biggest problems facing NASA today is to provide scientists efficient access to a large number of distributed databases. Our pointer-based incremental database access method, VIEWCACHE, provides such an interface for accessing distributed data sets and directories. VIEWCACHE allows database browsing and search performing inter-database cross-referencing with no actual data movement between database sites. This organization and processing is especially suitable for managing Astrophysics databases which are physically distributed all over the world. Once the search is complete, the set of collected pointers pointing to the desired data are cached. VIEWCACHE includes spatial access methods for accessing image data sets, which provide much easier query formulation by referring directly to the image and very efficient search for objects contained within a two-dimensional window. We will develop and optimize a VIEWCACHE External Gateway Access to database management systems to facilitate distributed database search.

  12. VIEWCACHE: An incremental pointer-based access method for autonomous interoperable databases

    NASA Technical Reports Server (NTRS)

    Roussopoulos, N.; Sellis, Timos

    1993-01-01

    One of the biggest problems facing NASA today is to provide scientists efficient access to a large number of distributed databases. Our pointer-based incremental data base access method, VIEWCACHE, provides such an interface for accessing distributed datasets and directories. VIEWCACHE allows database browsing and search performing inter-database cross-referencing with no actual data movement between database sites. This organization and processing is especially suitable for managing Astrophysics databases which are physically distributed all over the world. Once the search is complete, the set of collected pointers pointing to the desired data are cached. VIEWCACHE includes spatial access methods for accessing image datasets, which provide much easier query formulation by referring directly to the image and very efficient search for objects contained within a two-dimensional window. We will develop and optimize a VIEWCACHE External Gateway Access to database management systems to facilitate database search.

  13. Design and achievement of an efficient low-order pointer multiplexing and mapping scheme

    NASA Astrophysics Data System (ADS)

    Chen, Yangyi; Su, Shaojing; Zuo, Zhen; Huang, Zhiping; Zhang, Yimeng

    2015-10-01

    With the improvement of people's living standard, the requirement of network is higher and higher. The rate and capacity of network communication are rising all the time, it 's outstanding on the backbone networks. The rate of backbone network had improved from 10G to 100G in recent years. This change also put forward new requirement for optical network equipment . The key technologies of lower order cross-connect equipment is discussing in this passage. This passage mainly discusses the following aspects: time division multiplexing of STM-1 lower-order pointer interpretation and lower -order pointer generation. By using the technologies discussed in this passage, the lower -order cross-connect devices has the higher cross-connect capacity under consuming the same logic resource, and the equipment will meet the requirement of the backbone network transmission capacity.

  14. Certified Absence of Dangling Pointers in a Language with Explicit Deallocation

    NASA Astrophysics Data System (ADS)

    de Dios, Javier; Montenegro, Manuel; Peña, Ricardo

    Safe is a first-order eager functional language with facilities for programmer controlled destruction of data structures. It provides also regions, i.e. disjoint parts of the heap, where the program allocates data structures, so that the runtime system does not need a garbage collector. A region is a collection of cells, each one big enough to allocate a data constructor. Deallocating cells or regions may create dangling pointers. The language is aimed at inferring and certifying memory safety properties in a Proof Carrying Code like environment. Some of its analyses have been presented elsewhere. The one relevant to this paper is a type system and a type inference algorithm guaranteeing that well-typed programs will be free of dangling pointers at runtime.

  15. Implementing MPI-IO atomic mode and shared file pointers using MPI one-sided communication.

    SciTech Connect

    Latham, R.; Ross, R.; Thakur, R.; Mathematics and Computer Science

    2007-07-01

    The ROMIO implementation of the MPI-IO standard provides a portable infrastructure for use on top of a variety of underlying storage targets. These targets vary widely in their capabilities, and in some cases additional effort is needed within ROMIO to support all MPI-IO semantics. Two aspects of the interface that can be problematic to implement are MPI-IO atomic mode and the shared file pointer access routines. Atomic mode requires enforcing strict consistency semantics, and shared file pointer routines require communication and coordination in order to atomically update a shared resource. For some file systems, native locks may be used to implement these features, but not all file systems have lock support. In this work, we describe algorithms for implementing efficient mutex locks using MPI-1 and the one-sided capabilities from MPI-2. We then show how these algorithms may be used to implement both MPI-IO atomic mode and shared file pointer methods for ROMIO without requiring any features from the underlying file system. We show that these algorithms can outperform traditional file system lock approaches. Because of the portable nature of these algorithms, they are likely useful in a variety of situations where distributed locking or coordination is needed in the MPI-2 environment.

  16. Student Perceptions of the Use of a Laser Pointer for Intra-Operative Guidance in Feline Castration.

    PubMed

    Badman, Märit; Höglund, Katja; Höglund, Odd V

    2016-01-01

    In veterinary clinical education, students perform surgery under guided supervision. This study aimed to determine if students' perception of how well they understood verbal guidance could be improved by using a laser pointer during feline castration. It was assumed that a teacher's use of a laser pointer could help students identify structures of importance during surgery. The hypothesis was that use of a laser pointer would improve student understanding of verbal guidance during surgery. Eighteen privately owned male cats were electively neutered by fourth- and fifth-year veterinary students at the Swedish University of Agricultural Sciences, Uppsala, Sweden. Each student performed orchiectomy on one cat. One testis was removed while the student received verbal guidance combined with a laser pointer, and the other testis was removed while the student received only verbal guidance. The use of a laser pointer alternated between first and second testis. After surgery, students rated how well they understood verbal guidance on a visual-analog scale (100 mm) for each instructional method. The two ratings were compared in a student's two-sided t-test. The median score with or without guidance with a laser pointer was 81 (59-96) and 54 (25-86), respectively (p<.001). This study showed that laser pointers enhanced verbal guidance given to students during surgery. The suggested mechanism of explanation is that the technology enabled a more precise guidance of location and identification of anatomic structures.

  17. Student Perceptions of the Use of a Laser Pointer for Intra-Operative Guidance in Feline Castration.

    PubMed

    Badman, Märit; Höglund, Katja; Höglund, Odd V

    2016-01-01

    In veterinary clinical education, students perform surgery under guided supervision. This study aimed to determine if students' perception of how well they understood verbal guidance could be improved by using a laser pointer during feline castration. It was assumed that a teacher's use of a laser pointer could help students identify structures of importance during surgery. The hypothesis was that use of a laser pointer would improve student understanding of verbal guidance during surgery. Eighteen privately owned male cats were electively neutered by fourth- and fifth-year veterinary students at the Swedish University of Agricultural Sciences, Uppsala, Sweden. Each student performed orchiectomy on one cat. One testis was removed while the student received verbal guidance combined with a laser pointer, and the other testis was removed while the student received only verbal guidance. The use of a laser pointer alternated between first and second testis. After surgery, students rated how well they understood verbal guidance on a visual-analog scale (100 mm) for each instructional method. The two ratings were compared in a student's two-sided t-test. The median score with or without guidance with a laser pointer was 81 (59-96) and 54 (25-86), respectively (p<.001). This study showed that laser pointers enhanced verbal guidance given to students during surgery. The suggested mechanism of explanation is that the technology enabled a more precise guidance of location and identification of anatomic structures. PMID:27128854

  18. Gyroscope-driven mouse pointer with an EMOTIV® EEG headset and data analysis based on Empirical Mode Decomposition.

    PubMed

    Rosas-Cholula, Gerardo; Ramirez-Cortes, Juan Manuel; Alarcon-Aquino, Vicente; Gomez-Gil, Pilar; Rangel-Magdaleno, Jose de Jesus; Reyes-Garcia, Carlos

    2013-08-14

    This paper presents a project on the development of a cursor control emulating the typical operations of a computer-mouse, using gyroscope and eye-blinking electromyographic signals which are obtained through a commercial 16-electrode wireless headset, recently released by Emotiv. The cursor position is controlled using information from a gyroscope included in the headset. The clicks are generated through the user's blinking with an adequate detection procedure based on the spectral-like technique called Empirical Mode Decomposition (EMD). EMD is proposed as a simple and quick computational tool, yet effective, aimed to artifact reduction from head movements as well as a method to detect blinking signals for mouse control. Kalman filter is used as state estimator for mouse position control and jitter removal. The detection rate obtained in average was 94.9%. Experimental setup and some obtained results are presented.

  19. Gyroscope-driven mouse pointer with an EMOTIV® EEG headset and data analysis based on Empirical Mode Decomposition.

    PubMed

    Rosas-Cholula, Gerardo; Ramirez-Cortes, Juan Manuel; Alarcon-Aquino, Vicente; Gomez-Gil, Pilar; Rangel-Magdaleno, Jose de Jesus; Reyes-Garcia, Carlos

    2013-01-01

    This paper presents a project on the development of a cursor control emulating the typical operations of a computer-mouse, using gyroscope and eye-blinking electromyographic signals which are obtained through a commercial 16-electrode wireless headset, recently released by Emotiv. The cursor position is controlled using information from a gyroscope included in the headset. The clicks are generated through the user's blinking with an adequate detection procedure based on the spectral-like technique called Empirical Mode Decomposition (EMD). EMD is proposed as a simple and quick computational tool, yet effective, aimed to artifact reduction from head movements as well as a method to detect blinking signals for mouse control. Kalman filter is used as state estimator for mouse position control and jitter removal. The detection rate obtained in average was 94.9%. Experimental setup and some obtained results are presented. PMID:23948873

  20. SEQ-POINTER: Next generation, planetary spacecraft remote sensing science observation design tool

    NASA Astrophysics Data System (ADS)

    Boyer, Jeffrey S.

    1994-11-01

    Since Mariner, NASA-JPL planetary missions have been supported by ground software to plan and design remote sensing science observations. The software used by the science and sequence designers to plan and design observations has evolved with mission and technological advances. The original program, PEGASIS (Mariners 4, 6, and 7), was re-engineered as POGASIS (Mariner 9, Viking, and Mariner 10), and again later as POINTER (Voyager and Galileo). Each of these programs were developed under technological, political, and fiscal constraints which limited their adaptability to other missions and spacecraft designs. Implementation of a multi-mission tool, SEQ POINTER, under the auspices of the JPL Multimission Operations Systems Office (MOSO) is in progress. This version has been designed to address the limitations experienced on previous versions as they were being adapted to a new mission and spacecraft. The tool has been modularly designed with subroutine interface structures to support interchangeable celestial body and spacecraft definition models. The computational and graphics modules have also been designed to interface with data collected from previous spacecraft, or on-going observations, which describe the surface of each target body. These enhancements make SEQ POINTER a candidate for low-cost mission usage, when a remote sensing science observation design capability is required. The current and planned capabilities of the tool will be discussed. The presentation will also include a 5-10 minute video presentation demonstrating the capabilities of a proto-Cassini Project version that was adapted to test the tool. The work described in this abstract was performed by the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.

  1. SEQ-POINTER: Next generation, planetary spacecraft remote sensing science observation design tool

    NASA Technical Reports Server (NTRS)

    Boyer, Jeffrey S.

    1994-01-01

    Since Mariner, NASA-JPL planetary missions have been supported by ground software to plan and design remote sensing science observations. The software used by the science and sequence designers to plan and design observations has evolved with mission and technological advances. The original program, PEGASIS (Mariners 4, 6, and 7), was re-engineered as POGASIS (Mariner 9, Viking, and Mariner 10), and again later as POINTER (Voyager and Galileo). Each of these programs were developed under technological, political, and fiscal constraints which limited their adaptability to other missions and spacecraft designs. Implementation of a multi-mission tool, SEQ POINTER, under the auspices of the JPL Multimission Operations Systems Office (MOSO) is in progress. This version has been designed to address the limitations experienced on previous versions as they were being adapted to a new mission and spacecraft. The tool has been modularly designed with subroutine interface structures to support interchangeable celestial body and spacecraft definition models. The computational and graphics modules have also been designed to interface with data collected from previous spacecraft, or on-going observations, which describe the surface of each target body. These enhancements make SEQ POINTER a candidate for low-cost mission usage, when a remote sensing science observation design capability is required. The current and planned capabilities of the tool will be discussed. The presentation will also include a 5-10 minute video presentation demonstrating the capabilities of a proto-Cassini Project version that was adapted to test the tool. The work described in this abstract was performed by the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.

  2. Structural features of a potential gas hydrate area in the Pointer Ridge off southwest Taiwan

    NASA Astrophysics Data System (ADS)

    Wang, Hsueh-Fen; Hsu, Shu-Kun; Tsai, Ching-Hui; Chen, Song-Chuen; Liu, Char-Shine; Lin, Hsiao-Shan

    2015-04-01

    The offshore area of the southwest Taiwan is located in the oblique convergence zone between the northern continental margin of South China Sea and the Manila accretionary wedge. To the west of the deformation front offshore southwestern Taiwan, the Pointer Ridge is located in the passive South China Sea continental margin. The continental margin is compose of extensional horst-and-graben structures. There are numerous submarine channels and linear ridge, formed due to the submarine erosion across the continental slope region. According to geophysical research off SW Taiwan, abundant gas hydrate may exist. In this study, our purpose is to understand the relationship between the near-seafloor structures of the Pointer Ridge and the gas hydrate formation off SW Taiwan. The data we used include multi-beam echo sounder (MBES), side-scan sonar (SSS), sub-bottom profiler (SBP) and the multi-channel reflection seismic (MCS) data. Our results show the pockmark and gas seepage structures mainly appear in the place where the gradient of the BSR thickness is maximum. Those sites contain authigenic carbonate signature shown in the sub-bottom profiler. We also observe several folds and faults structures in this extensional background; however, these compressional features need further studies.

  3. Optimizing Semantic Pointer Representations for Symbol-Like Processing in Spiking Neural Networks.

    PubMed

    Gosmann, Jan; Eliasmith, Chris

    2016-01-01

    The Semantic Pointer Architecture (SPA) is a proposal of specifying the computations and architectural elements needed to account for cognitive functions. By means of the Neural Engineering Framework (NEF) this proposal can be realized in a spiking neural network. However, in any such network each SPA transformation will accumulate noise. By increasing the accuracy of common SPA operations, the overall network performance can be increased considerably. As well, the representations in such networks present a trade-off between being able to represent all possible values and being only able to represent the most likely values, but with high accuracy. We derive a heuristic to find the near-optimal point in this trade-off. This allows us to improve the accuracy of common SPA operations by up to 25 times. Ultimately, it allows for a reduction of neuron number and a more efficient use of both traditional and neuromorphic hardware, which we demonstrate here. PMID:26900931

  4. Optimizing Semantic Pointer Representations for Symbol-Like Processing in Spiking Neural Networks

    PubMed Central

    Gosmann, Jan; Eliasmith, Chris

    2016-01-01

    The Semantic Pointer Architecture (SPA) is a proposal of specifying the computations and architectural elements needed to account for cognitive functions. By means of the Neural Engineering Framework (NEF) this proposal can be realized in a spiking neural network. However, in any such network each SPA transformation will accumulate noise. By increasing the accuracy of common SPA operations, the overall network performance can be increased considerably. As well, the representations in such networks present a trade-off between being able to represent all possible values and being only able to represent the most likely values, but with high accuracy. We derive a heuristic to find the near-optimal point in this trade-off. This allows us to improve the accuracy of common SPA operations by up to 25 times. Ultimately, it allows for a reduction of neuron number and a more efficient use of both traditional and neuromorphic hardware, which we demonstrate here. PMID:26900931

  5. Pretty Lights and Glowing Rocks: Using Lasers Pointers to Demonstrate Optical Phenomena

    NASA Astrophysics Data System (ADS)

    Huang, A.; Bodner, G.; Zheng, C.

    2011-12-01

    Green and violet lasers have recently become both inexpensive and portable, more than 70 years after the first laser was built. Despite the technology's age, the general public is still fascinated by the exotic nature of laser light. This activity uses green and violet laser pointers to produce a veritable rainbow of colors from household items and common minerals. Our objective is to create an educational experience which uses vivid colors and appealing effects to engage the audience, while teaching basic optical concepts such as scattering, fluorescence, Snell's law, and the quantum nature of light. The activity can be adapted to a lecture demonstration or to a laboratory exercise in which students handle the lasers and test samples. Learning outcomes have not been formally measured, but this demonstration will still captivate audiences in museum settings, community outreach programs, and introductory science courses.

  6. Analogue mouse pointer control via an online steady state visual evoked potential (SSVEP) brain-computer interface

    NASA Astrophysics Data System (ADS)

    Wilson, John J.; Palaniappan, Ramaswamy

    2011-04-01

    The steady state visual evoked protocol has recently become a popular paradigm in brain-computer interface (BCI) applications. Typically (regardless of function) these applications offer the user a binary selection of targets that perform correspondingly discrete actions. Such discrete control systems are appropriate for applications that are inherently isolated in nature, such as selecting numbers from a keypad to be dialled or letters from an alphabet to be spelled. However motivation exists for users to employ proportional control methods in intrinsically analogue tasks such as the movement of a mouse pointer. This paper introduces an online BCI in which control of a mouse pointer is directly proportional to a user's intent. Performance is measured over a series of pointer movement tasks and compared to the traditional discrete output approach. Analogue control allowed subjects to move the pointer faster to the cued target location compared to discrete output but suffers more undesired movements overall. Best performance is achieved when combining the threshold to movement of traditional discrete techniques with the range of movement offered by proportional control.

  7. Peace and Conflict Research in the Age of the Cholera: Ten Pointers to the Future of Peace Studies.

    ERIC Educational Resources Information Center

    Galtung, Johan

    1996-01-01

    Presents 10 pointers that can lead to constructive peace making. Covers issues such as a definition of peace; the training of peace workers; the role of the state system in creating conflict; legitimizing peace actions; and suggestions for future peace creation. Discusses the links between direct, structural, and cultural violence. (DSK)

  8. Fluid Flow Processes Study: from a 3D seismic data set in the Pointer Ridge offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Han, Wei-Chung; Liu, Char-Shine; Chen, Liwen; Chi, Wu-Cheng; Lin, Che-Chuan

    2016-04-01

    This study analyzes a 3D seismic cube in the Pointer Ridge for understanding the fluid flow processes in subsurface. Pointer Ridge is a ridge situated on the passive China continental margin and is suggested as a potential prospect for future gas hydrate development. High methane flux rate, active gas venting and seismic chimneys have been observed in this area, which are direct evidences for active ongoing fluid migration processes. To find the possible fluid conduits and to understand how the fluids have migrated along those conduits, we firstly identify the structural and sedimentary features from this 3D seismic cube in our study area. Secondly, seismic attribute analyses are carried out for detecting fluid conduits and evaluating the contribution of recognized faults/fractures for fluid flow, respectively. Finally, we propose conceptual models to illustrate how fluids have migrated along those conduits to the seafloor and how those conduits have developed. The results show: 1) a major NE-SW striking normal fault (PR Fault) separates a depositional field on the hanging wall and a erosional field on the footwall; 2) the PR Fault zone itself and the chimneys in its footwall act as main conduits for focused fluid flow migrating to the seafloor; 3) the development of the chimneys in the Pointer Ridge area are highly controlled by the erosion and deposition processes. Since the ongoing fluid flow processes will increase the seafloor instabilities and the Pointer Ridge is a gas hydrate leaking site, our results could provide useful information for further risk evaluation.

  9. A Mobile Robot Operation with Instruction of Neck Movement using Laser Pointer

    NASA Astrophysics Data System (ADS)

    Shibata, Satoru; Yamamoto, Tomonori; Jindai, Mitsuru

    A human-robot system in which a mobile robot follows the movement of the laser spot projected on the floor by the laser pointer attached at the human head is considered. Human gives instruction of desired movement to the omni-directional mobile robot by rotating his or her head. The mobile robot can realize intended movement by following the movement of the laser spot on the floor. By projecting an instructive point to be followed by the mobile robot, the user can clearly recognize the relation between the direction being faced and the desired position of the mobile robot. In addition, the user can convey a motion trajectory to the mobile robot continuously. Kansei transfer function is introduced between the instruction movement of the laser spot and following motion of the robot to realize psychologically acceptable motion of the robot. In addition, three modes, stopping mode, following mode, and autonomous motion mode to the target, are considered. The effectiveness of the proposed system was discussed experimentally, and confirmed by the smooth trajectory of the following motion of the mobile robot and good psychological evaluations.

  10. Exact time-dependent pointer state in a Jaynes-Cummings model with intensity-dependent level shift

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Xu, Chang; Ren, Zhongzhou

    2015-06-01

    We show that in the Jaynes-Cummings model with an intensity-dependent level shift whose magnitude is tuned to give rise to periodic collapse and revival, there exists a kind of time evolution where the two-level system and a coherent boson field stay absolutely disentangled throughout the evolution, in spite of the nonzero interaction between them. This constitutes an explicit example for an exact time-dependent pointer state of the two-level system, which perhaps distinguishes this evolution from all known disentangled evolutions in JC-related models. The construction of such an evolution is made possible by a vast level degeneracy in the energy level structure. Two possible ways to observe this phenomenon are also discussed. We believe that the present work could contribute to the understanding of pointer states.

  11. Cost-effective handoff scheme based on mobility-aware dual pointer forwarding in proxy mobile IPv6 networks.

    PubMed

    Son, Seungsik; Jeong, Jongpil

    2014-01-01

    In this paper, a mobility-aware Dual Pointer Forwarding scheme (mDPF) is applied in Proxy Mobile IPv6 (PMIPv6) networks. The movement of a Mobile Node (MN) is classified as intra-domain and inter-domain handoff. When the MN moves, this scheme can reduce the high signaling overhead for intra-handoff/inter-handoff, because the Local Mobility Anchor (LMA) and Mobile Access Gateway (MAG) are connected by pointer chains. In other words, a handoff is aware of low mobility between the previously attached MAG (pMAG) and newly attached MAG (nMAG), and another handoff between the previously attached LMA (pLMA) and newly attached LMA (nLMA) is aware of high mobility. Based on these mobility-aware binding updates, the overhead of the packet delivery can be reduced. Also, we analyse the binding update cost and packet delivery cost for route optimization, based on the mathematical analytic model. Analytical results show that our mDPF outperforms the PMIPv6 and the other pointer forwarding schemes, in terms of reducing the total cost of signaling.

  12. Cost-effective handoff scheme based on mobility-aware dual pointer forwarding in proxy mobile IPv6 networks.

    PubMed

    Son, Seungsik; Jeong, Jongpil

    2014-01-01

    In this paper, a mobility-aware Dual Pointer Forwarding scheme (mDPF) is applied in Proxy Mobile IPv6 (PMIPv6) networks. The movement of a Mobile Node (MN) is classified as intra-domain and inter-domain handoff. When the MN moves, this scheme can reduce the high signaling overhead for intra-handoff/inter-handoff, because the Local Mobility Anchor (LMA) and Mobile Access Gateway (MAG) are connected by pointer chains. In other words, a handoff is aware of low mobility between the previously attached MAG (pMAG) and newly attached MAG (nMAG), and another handoff between the previously attached LMA (pLMA) and newly attached LMA (nLMA) is aware of high mobility. Based on these mobility-aware binding updates, the overhead of the packet delivery can be reduced. Also, we analyse the binding update cost and packet delivery cost for route optimization, based on the mathematical analytic model. Analytical results show that our mDPF outperforms the PMIPv6 and the other pointer forwarding schemes, in terms of reducing the total cost of signaling. PMID:24555172

  13. Improving interaction in navigated surgery by combining a pan-tilt mounted laser and a pointer with triggering

    NASA Astrophysics Data System (ADS)

    Ojdanic, D.; Chen, L.; Peitgen, H.-O.

    2012-02-01

    User interaction during navigated surgery is often a critical issue in the overall procedure, as several complex aspects must be considered, such as sterility, workflow, field of view, and cognitive load. This work introduces a new approach for intraoperative interaction that seamlessly fits the high surgical requirements. A navigation system, typically consisting of a tracking system and a monitor for 3D virtual models, is augmented with a tracked pointer with triggering functionality and a pan-tilt mounted laser. The pointer, which is sterile and can be applied for landmark-based organ registration, is used for wireless interaction with the monitor scene. The laser system enables the calibration of the monitor, which is out of the tracking system's range. Moreover, the laser beam can focus on any organ point defined on the virtual model, which improves targeting or visual feedback during intervention. The calibration of the laser system, monitor, and triggered pointer is achieved by an effective procedure, which can be easily repeated in operating room. The mathematical background of the calibration is based on the Levenberg-Marquardt and Umeyama's algorithms.

  14. Effects of trajectory exercise using a laser pointer on electromyographic activities of the gluteus maximus and erector spinae during bridging exercises.

    PubMed

    Kim, Yu-Ri; Yoo, Won-Gyu

    2016-01-01

    [Purpose] The purpose of this study was to investigate activities of the hip extensors and erector spinae during bridging exercise by using instruments with a laser pointer on the pelvic belt. [Subjects] Twelve subjects (age, 23 to 33 years) with non-specific low back pain volunteered for this study. [Methods] Subjects performed bridging exercises with and without trajectory exercises by using a laser pointer fixed to a pelvic strap. The erector spinae, gluteus maximus and hamstring activities with and without trajectory exercises using a laser pointer were recorded on using electromyography. [Results] Compared to the without laser pointer group, the group that underwent bridging with trajectory exercises using a laser pointer had significantly higher gluteus maximus activity and significantly lower erector spinae activity. Significantly higher gluteus maximus/erector spinae activity ratios were observed when performing trajectory exercises using a laser pointer during bridging exercises. [Conclusion] This result suggests that trajectory exercises using a laser pointer during a bridging exercise would be effective for improving gluteus maximus activity. PMID:27065555

  15. Effects of trajectory exercise using a laser pointer on electromyographic activities of the gluteus maximus and erector spinae during bridging exercises

    PubMed Central

    Kim, Yu-Ri; Yoo, Won-Gyu

    2016-01-01

    [Purpose] The purpose of this study was to investigate activities of the hip extensors and erector spinae during bridging exercise by using instruments with a laser pointer on the pelvic belt. [Subjects] Twelve subjects (age, 23 to 33 years) with non-specific low back pain volunteered for this study. [Methods] Subjects performed bridging exercises with and without trajectory exercises by using a laser pointer fixed to a pelvic strap. The erector spinae, gluteus maximus and hamstring activities with and without trajectory exercises using a laser pointer were recorded on using electromyography. [Results] Compared to the without laser pointer group, the group that underwent bridging with trajectory exercises using a laser pointer had significantly higher gluteus maximus activity and significantly lower erector spinae activity. Significantly higher gluteus maximus/erector spinae activity ratios were observed when performing trajectory exercises using a laser pointer during bridging exercises. [Conclusion] This result suggests that trajectory exercises using a laser pointer during a bridging exercise would be effective for improving gluteus maximus activity. PMID:27065555

  16. Effects of trajectory exercise using a laser pointer on electromyographic activities of the gluteus maximus and erector spinae during bridging exercises.

    PubMed

    Kim, Yu-Ri; Yoo, Won-Gyu

    2016-01-01

    [Purpose] The purpose of this study was to investigate activities of the hip extensors and erector spinae during bridging exercise by using instruments with a laser pointer on the pelvic belt. [Subjects] Twelve subjects (age, 23 to 33 years) with non-specific low back pain volunteered for this study. [Methods] Subjects performed bridging exercises with and without trajectory exercises by using a laser pointer fixed to a pelvic strap. The erector spinae, gluteus maximus and hamstring activities with and without trajectory exercises using a laser pointer were recorded on using electromyography. [Results] Compared to the without laser pointer group, the group that underwent bridging with trajectory exercises using a laser pointer had significantly higher gluteus maximus activity and significantly lower erector spinae activity. Significantly higher gluteus maximus/erector spinae activity ratios were observed when performing trajectory exercises using a laser pointer during bridging exercises. [Conclusion] This result suggests that trajectory exercises using a laser pointer during a bridging exercise would be effective for improving gluteus maximus activity.

  17. Laser-pointer-induced self-focusing effect in hybrid-aligned dye-doped liquid crystals

    PubMed Central

    Wang, Jing; Aihara, Yosuke; Kinoshita, Motoi; Mamiya, Jun-ichi; Priimagi, Arri; Shishido, Atsushi

    2015-01-01

    Nonlinear optics deals with phenomena where “light controls light”; e.g., there is mediation by an intensity-dependent medium through which light propagates. This field has attracted much attention for its immense potential in applications dependent on nonlinear processes, such as frequency conversion, multiple-photon absorption, self-phase modulation, and so on. However, such nonlinearities are typically only observed at very high light intensities and thus they require costly lasers. Here, we report on a self-focusing effect induced with a 1 mW handheld laser pointer. We prepared polymer-stabilized dye-doped liquid crystals, in which the molecular director orientation gradually changes from homeotropic at one surface to homogeneous at the other. This is referred to as hybrid alignment. In such films, the threshold intensity needed to form diffraction rings was reduced by a factor of 8.5 compared to that in conventional homeotropic cells, which enabled the induction of the self-focusing effect with a laser pointer. PMID:25944052

  18. Laser-pointer-induced self-focusing effect in hybrid-aligned dye-doped liquid crystals

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Aihara, Yosuke; Kinoshita, Motoi; Mamiya, Jun-Ichi; Priimagi, Arri; Shishido, Atsushi

    2015-05-01

    Nonlinear optics deals with phenomena where “light controls light” e.g., there is mediation by an intensity-dependent medium through which light propagates. This field has attracted much attention for its immense potential in applications dependent on nonlinear processes, such as frequency conversion, multiple-photon absorption, self-phase modulation, and so on. However, such nonlinearities are typically only observed at very high light intensities and thus they require costly lasers. Here, we report on a self-focusing effect induced with a 1 mW handheld laser pointer. We prepared polymer-stabilized dye-doped liquid crystals, in which the molecular director orientation gradually changes from homeotropic at one surface to homogeneous at the other. This is referred to as hybrid alignment. In such films, the threshold intensity needed to form diffraction rings was reduced by a factor of 8.5 compared to that in conventional homeotropic cells, which enabled the induction of the self-focusing effect with a laser pointer.

  19. Laser-pointer-induced self-focusing effect in hybrid-aligned dye-doped liquid crystals.

    PubMed

    Wang, Jing; Aihara, Yosuke; Kinoshita, Motoi; Mamiya, Jun-Ichi; Priimagi, Arri; Shishido, Atsushi

    2015-01-01

    Nonlinear optics deals with phenomena where "light controls light"; e.g., there is mediation by an intensity-dependent medium through which light propagates. This field has attracted much attention for its immense potential in applications dependent on nonlinear processes, such as frequency conversion, multiple-photon absorption, self-phase modulation, and so on. However, such nonlinearities are typically only observed at very high light intensities and thus they require costly lasers. Here, we report on a self-focusing effect induced with a 1 mW handheld laser pointer. We prepared polymer-stabilized dye-doped liquid crystals, in which the molecular director orientation gradually changes from homeotropic at one surface to homogeneous at the other. This is referred to as hybrid alignment. In such films, the threshold intensity needed to form diffraction rings was reduced by a factor of 8.5 compared to that in conventional homeotropic cells, which enabled the induction of the self-focusing effect with a laser pointer. PMID:25944052

  20. Extreme pointer years in tree-ring records of Central Spain as evidence of climatic events and the eruption of the Huaynaputina Volcano (Peru, 1600 AD)

    NASA Astrophysics Data System (ADS)

    Génova, M.

    2012-04-01

    The study of pointer years of numerous tree-ring chronologies of the central Iberian Peninsula (Sierra de Guadarrama) could provide complementary information about climate variability over the last 405 yr. In total, 64 pointer years have been identified: 30 negative (representing minimum growths) and 34 positive (representing maximum growths), the most significant of these being 1601, 1963 and 1996 for the negative ones, and 1734 and 1737 for the positive ones. Given that summer precipitation was found to be the most limiting factor for the growth of Pinus in the Sierra de Guadarrama in the second half of the 20th century, it is also an explanatory factor in almost 50% of the extreme growths. Furthermore, these pointer years and intervals are not evenly distributed throughout time. Both in the first half of the 17th and in the second half of 20th, they were more frequent and more extreme and these periods are the most notable for the frequency of negative pointer years in Central Spain. The interval 1600-1602 is of special significance, being one of the most unfavourable for tree growth in the centre of Spain, with 1601 representing the minimum index in the regional chronology. We infer that this special minimum annual increase was the effect of the eruption of Huaynaputina, which occurred in Peru at the beginning of 1600 AD. This is the first time that the effects of this eruption in the tree-ring records of Southern Europe have been demonstrated.

  1. Investigative Studies of Refractive Indices of Liquids and a Demonstration of Refraction by the Use of a Laser Pointer and a Lazy Susan

    ERIC Educational Resources Information Center

    Wong, Siu Ling; Mak, Se-yuen

    2008-01-01

    We describe the design of a simple homemade apparatus for the measurement of the refractive indices of liquids and demonstration of refraction. A circular transparent plastic tank and a lazy Susan are held concentrically. A laser pointer is mounted on the lazy Susan with its laser beam pointing radially through the centre of the plastic tank.…

  2. The presence of diatom algae in a tracheal wash from a German Wirehaired Pointer with aspiration pneumonia.

    PubMed

    Benson, Catherine J; Edlund, Mark B; Gray, Sarah; Powell, Lisa; Paulin-Curlee, Geisa; Armien, Anibal; Overmann, Jed A

    2013-06-01

    A 7-year-old spayed female German Wirehaired Pointer was presented with difficulty breathing after being found seizing in a water-filled drainage ditch while out hunting. Aspirates from a tracheal wash contained numerous degenerate neutrophils, fewer macrophages, some of which contained basophilic debris, low numbers of extracellular diatoms, and a single intracellular short bacterial rod. As the dog continued to clinically decline and could not be weaned from oxygen support, the owners chose euthanasia. The major necropsy finding was a severe granulomatous bronchopneumonia that was likely due to aspiration of foreign material based on the microscopic presence of plant-like material, bi-refringent crystalline material, non-cellular debris, and occasional fungal structures. Diatoms are a class of algae that live primarily in water. Diatom analysis has been used, with some controversy, in human forensics to assist in documenting drowning as the cause of death. In this case, given the clinical history, the presence of diatoms and inflammation in the tracheal wash were interpreted as a likely result of the aspiration of surface water. To our knowledge, this is the first reported case of diatoms observed in a cytologic specimen in a nonhuman mammal with aspiration pneumonia.

  3. Pointers for Parents, 1974.

    ERIC Educational Resources Information Center

    Florida State Dept. of Education, Tallahassee.

    This booklet was written for parents of children in the Follow Through Program. It provides useful tips on money management, home-school relationship, and health and nutrition. The section on money management discusses food stamps, social security, insurance, buying on credit and installment, budgeting hints, and shopping hints. The section on…

  4. Pointers from the Americas.

    PubMed

    Aragon-choudhury, P

    1992-01-01

    During a sharing session which took place at a conference sponsored by the Philippine Institute for Social Studies and Action in 1991, Peruvian Victoria Villanueva and US citizen Margaret Ann Schuller discussed their work. Schuller reported on her upcoming book entitled "Freedom from Violence: Women's Strategies Around the World." In addition to proposing a definition of violence against women, the book will include 12 case studies from Malaysia, Bolivia, Mexico, India, Pakistan, Thailand, Sri Lanka, Brazil, Zimbabwe, Chile, Africa, and Alaska describing how national organizations of women are dealing with the problem. An important advance is the development of a framework to look at the connection which exists between violence and health issues. Villanueva described the work of the Movimiento Manuela Ramos, which was organized informally to deal with reproductive rights and abortion and has since expanded to parent groups of women who defend legal and medical cases as paid paralegals. Manuela Ramos uses popular media, traditional drama, and even state television to publicize its issues. Manuela Ramos has accomplished important work on rape, unsafe abortion, and maternal mortality, but most importantly, the women involved with the organization have had the opportunity to develop their self-esteem. PMID:12288567

  5. Pointers from the Americas.

    PubMed

    Aragon-choudhury, P

    1992-01-01

    During a sharing session which took place at a conference sponsored by the Philippine Institute for Social Studies and Action in 1991, Peruvian Victoria Villanueva and US citizen Margaret Ann Schuller discussed their work. Schuller reported on her upcoming book entitled "Freedom from Violence: Women's Strategies Around the World." In addition to proposing a definition of violence against women, the book will include 12 case studies from Malaysia, Bolivia, Mexico, India, Pakistan, Thailand, Sri Lanka, Brazil, Zimbabwe, Chile, Africa, and Alaska describing how national organizations of women are dealing with the problem. An important advance is the development of a framework to look at the connection which exists between violence and health issues. Villanueva described the work of the Movimiento Manuela Ramos, which was organized informally to deal with reproductive rights and abortion and has since expanded to parent groups of women who defend legal and medical cases as paid paralegals. Manuela Ramos uses popular media, traditional drama, and even state television to publicize its issues. Manuela Ramos has accomplished important work on rape, unsafe abortion, and maternal mortality, but most importantly, the women involved with the organization have had the opportunity to develop their self-esteem.

  6. Pointers for Parenting.

    ERIC Educational Resources Information Center

    Bessant, Helen P., Ed.

    Presented are 11 brief articles designed to help parents enhance their children's school performance and generally improve the home environment. Included is information on the following topics: the role of the social worker in parent education, home activities to improve a child's reading skills, developing listening skill through instructional…

  7. Extreme pointer years in tree-ring records of Central Spain as evidence of volcanic eruptions (Huaynaputina, Peru, 1600 AC) and other climatic events

    NASA Astrophysics Data System (ADS)

    Génova, M.

    2011-12-01

    The study of pointer years based on the numerous tree-ring chronologies of the central Iberian Peninsula (Sierra de Guadarrama) could provide complementary information about climate variability over the last 405 years. In total, 64 pointer years have been identified: 30 negative (representing minimum growths) and 34 positive (representing maximum growths), the most significant of these being 1601, 1963 and 1996 for the negative ones, and 1734 and 1737 for the positive ones. Given that summer precipitation has been the most incident factor in the general variability of growth of Pinus in the Sierra de Guadarrama in the second half of the 20th century, it is also an explanatory factor in almost 50% of the extreme growths. Furthermore, the data show that there has been variability over the centuries in the distribution of the frequencies of pointer years and intervals. The first half of the 17th century, together with the second half of the 20th century, constitute the two most notable periods for the frequency of negative pointer years in Central Spain. This variability was sufficiently notable to affirm that, both in the 17th and 20th centuries, the macroclimatic anomalies that affected growth were more frequent and more extreme than in the other two centuries analysed. The period 1600-1602 is of special significance, being one of the most unfavourable for tree growth in the centre of Spain, with 1601 representing the minimum index in the regional chronology. It is possible to infer that these phenomena are the effect of the eruption of Huaynaputina, which occurred in Peru at the beginning of 1600 AD. This is the first time that the effects of this eruption in the tree-ring records of central and southern Europe have been demonstrated.

  8. Teuchos::RefCountPtr beginner's guide : an introduction to the Trilinos smart reference-counted pointer class for (almost) automatic dynamic memory management in C++.

    SciTech Connect

    Bartlett, Roscoe A

    2004-06-01

    Dynamic memory management in C++ is one of the most common areas of difficulty and errors for amateur and expert C++ developers alike. The improper use of operator new and operator delete is arguably the most common cause of incorrect program behavior and segmentation faults in C++ programs. Here we introduce a templated concrete C++ class Teuchos::RefCountPtr<>, which is part of the Trilinos tools package Teuchos, that combines the concepts of smart pointers and reference counting to build a low-overhead but effective tool for simplifying dynamic memory management in C++. We discuss why the use of raw pointers for memory management, managed through explicit calls to operator new and operator delete, is so difficult to accomplish without making mistakes and how programs that use raw pointers for memory management can easily be modified to use RefCountPtr<>. In addition, explicit calls to operator delete is fragile and results in memory leaks in the presents of C++ exceptions. In its most basic usage, RefCountPtr<> automatically determines when operator delete should be called to free an object allocated with operator new and is not fragile in the presents of exceptions. The class also supports more sophisticated use cases as well. This document describes just the most basic usage of RefCountPtr<> to allow developers to get started using it right away. However, more detailed information on the design and advanced features of RefCountPtr<> is provided by the companion document 'Teuchos::RefCountPtr : The Trilinos Smart Reference-Counted Pointer Class for (Almost) Automatic Dynamic Memory Management in C++'.

  9. Comparative efficacy of new interfaces for intra-procedural imaging review: the Microsoft Kinect, Hillcrest Labs Loop Pointer, and the Apple iPad.

    PubMed

    Chao, Cherng; Tan, Justin; Castillo, Edward M; Zawaideh, Mazen; Roberts, Anne C; Kinney, Thomas B

    2014-08-01

    We adapted and evaluated the Microsoft Kinect (touchless interface), Hillcrest Labs Loop Pointer (gyroscopic mouse), and the Apple iPad (multi-touch tablet) for intra-procedural imaging review efficacy in a simulation using MIM Software DICOM viewers. Using each device, 29 radiologists executed five basic interactions to complete the overall task of measuring an 8.1-cm hepatic lesion: scroll, window, zoom, pan, and measure. For each interaction, participants assessed the devices on a 3-point subjective scale (3 = highest usability score). The five individual scores were summed to calculate a subjective composite usability score (max 15 points). Overall task time to completion was recorded. Each user also assessed each device for its potential to jeopardize a sterile field. The composite usability scores were as follows: Kinect 9.9 (out of 15.0; SD = 2.8), Loop Pointer 12.9 (SD = 13.5), and iPad 13.5 (SD = 1.8). Mean task completion times were as follows: Kinect 156.7 s (SD = 86.5), Loop Pointer 51.5 s (SD = 30.6), and iPad 41.1 s (SD = 25.3). The mean hepatic lesion measurements were as follows: Kinect was 7.3 cm (SD = 0.9), Loop Pointer 7.8 cm (SD = 1.1), and iPad 8.2 cm (SD = 1.2). The mean deviations from true hepatic lesion measurement were as follows: Kinect 1.0 cm and for both the Loop Pointer and iPad, 0.9 cm (SD = 0.7). The Kinect had the least and iPad had the most subjective concern for compromising the sterile field. A new intra-operative imaging review interface may be near. Most surveyed foresee these devices as useful in procedures, and most do not anticipate problems with a sterile field. An ideal device would combine iPad's usability and accuracy with the Kinect's touchless aspect.

  10. Trace-distance correlations for X states and the emergence of the pointer basis in Markovian and non-Markovian regimes

    NASA Astrophysics Data System (ADS)

    Obando, Paola C.; Paula, Fagner M.; Sarandy, Marcelo S.

    2015-09-01

    We provide analytical expressions for classical and total trace-norm (Schatten 1-norm) geometric correlations in the case of two-qubit X states. As an application, we consider the open-system dynamical behavior of such correlations under phase and generalized amplitude damping evolutions. Then, we show that geometric classical correlations can characterize the emergence of the pointer basis of an apparatus subject to decoherence in either Markovian or non-Markovian regimes. In particular, as a non-Markovian effect, we obtain a time delay for the information to be retrieved from the apparatus by a classical observer. Moreover, we show that the set of initial X states exhibiting sudden transitions in the geometric classical correlation has nonzero measure.

  11. US Coast Guard/US Maritime Administration Cooperative Research on marine engine exhaust emissions. Marine exhaust emissions measurement of the M/V Kings Pointer. Final report

    SciTech Connect

    Allen, S.J.; Bentz, A.P.

    1996-07-01

    This report presents the results of emissions testing conducted on board the M/V KINGS POINTER in May 1995. The objective of this testing was to conduct baseline instrumentation, monitoring, and evaluation of the engine exhaust emissions as part of joint U.S. Coast Guard/Maritime Administration cooperative research on controlling air pollution from ships. The U.S. Coast Guard`s interest in emissions testing arises from both its desire to meet all federal and state air quality regulations and the fact that in the future it may be called upon to enforce regulations in the marine environment. The U.S. Maritime Administration`s interest in this and related research is based on its efforts to assure that its vessels and those of the privately-owned U.S. Flag Merchant Marine can comply with future air pollution control requirements. Underway tests were conducted of the 224-foot M/V KINGS POINTER in which two of its four diesel-electric generators were sampled for NO, NO2, CO, and SO2 in the exhaust. Additional data on fuel flow and power output were collected at five speeds over the full range of vessel operating ranges. NOx values were calculated and compared with standards proposed by the Environmental Protection Agency (EPA) and the International Maritime Organization (IMO). Results showed that average NOx values were 9.4 g/kWh which is slightly below the 10.9 g/kWh upper limit or cap that is being proposed by the IMO for a diesel engine with a rated speed of 1200 RPM. Additional conclusions and recommendations on the technique of portable emissions monitoring instrumentation are made.

  12. Computer Workstation: Pointer/Mouse

    MedlinePlus

    ... and long term use. Potential Hazards: When the sensitivity for the input device is not appropriately set, ... provide adequate control. A mouse that has insufficient sensitivity may require large deviation of the wrist to ...

  13. The driven spinning top

    NASA Astrophysics Data System (ADS)

    Grosu, Ioan; Featonby, David

    2016-05-01

    This driven top is quite a novelty and can, with some trials, be made using the principles outlined here. This new top has many applications in developing both understanding and skills and these are detailed in the article. Depending on reader’s available time and motivation they may feel an urge to make one themselves, or simply invest a few pounds in the one that has been designed, tested and manufactured to a high standard. Either way the unique design of the driven top can provide several hours of interesting experimentation. Our aim here is simply to inform and inspire readers to further investigation and experimentation.

  14. Plasma sheath driven targets

    NASA Astrophysics Data System (ADS)

    Brownell, J. H.; Freeman, B. L.

    1980-02-01

    Plasma focus driven target implosions are simulated using hydrodynamic-burn codes. Support is given to the idea that the use of a target in a plasma focus should allow 'impedance matching' between the fuel and gun, permitting larger fusion yields from a focus-target geometry than the scaling laws for a conventional plasma focus would predict.

  15. Data Driven Teachers

    ERIC Educational Resources Information Center

    Tech & Learning, 2009

    2009-01-01

    Data-driven decision-making (DDDM) is a system of teaching and management practices that gets better information about students into the hands of classroom teachers. This article discusses the five major elements: (1) good baseline data; (2) measurable instructional goals; (3) frequent formative assessment; (4) professional learning communities;…

  16. The Driven Spinning Top

    ERIC Educational Resources Information Center

    Grosu, Ioan; Featonby, David

    2016-01-01

    This driven top is quite a novelty and can, with some trials, be made using the principles outlined here. This new top has many applications in developing both understanding and skills and these are detailed in the article. Depending on reader's available time and motivation they may feel an urge to make one themselves, or simply invest a few…

  17. Argument-Driven Inquiry

    ERIC Educational Resources Information Center

    Sampson, Victor; Grooms, Jonathon; Walker, Joi

    2009-01-01

    Argument-Driven Inquiry (ADI) is an instructional model that enables science teachers to transform a traditional laboratory activity into a short integrated instructional unit. To illustrate how the ADI instructional model works, this article describes an ADI lesson developed for a 10th-grade chemistry class. This example lesson was designed to…

  18. Data-Driven Districts.

    ERIC Educational Resources Information Center

    LaFee, Scott

    2002-01-01

    Describes the use of data-driven decision-making in four school districts: Plainfield Public Schools, Plainfield, New Jersey; Palo Alto Unified School District, Palo Alto, California; Francis Howell School District in eastern Missouri, northwest of St. Louis; and Rio Rancho Public Schools, near Albuquerque, New Mexico. Includes interviews with the…

  19. Laser driven radiography

    SciTech Connect

    Perry, M.D.; Sefcik, J.; Cowan, T.

    1997-12-20

    Intense laser (> 1021 W/cm{sup 3}) driven hard x-ray sources offer a new alternative to conventional electron accelerator Bremsstrahlung sources. These laser driven sources offer considerable simplicity in design and potential cost advantage for multiple axis views. High spatial and temporal resolution is achievable as a result of the very small source size (<100 um) and short-duration of the laser pulse. We have begun a series of experiments with the Petawatt laser at LLNL to determine the photon flux achievable with these sources and assess their potential for Stewardship applications. Additionally, we are developing a conceptual design and cost estimate of a multi-pulse, multi-axis (up to five) radiographic facility utilizing the Contained Firing Facility at site 300 and existing laser hardware.

  20. Test-driven programming

    NASA Astrophysics Data System (ADS)

    Georgiev, Bozhidar; Georgieva, Adriana

    2013-12-01

    In this paper, are presented some possibilities concerning the implementation of a test-driven development as a programming method. Here is offered a different point of view for creation of advanced programming techniques (build tests before programming source with all necessary software tools and modules respectively). Therefore, this nontraditional approach for easier programmer's work through building tests at first is preferable way of software development. This approach allows comparatively simple programming (applied with different object-oriented programming languages as for example JAVA, XML, PYTHON etc.). It is predictable way to develop software tools and to provide help about creating better software that is also easier to maintain. Test-driven programming is able to replace more complicated casual paradigms, used by many programmers.

  1. Stochastically driven genetic circuits

    NASA Astrophysics Data System (ADS)

    Tsimring, L. S.; Volfson, D.; Hasty, J.

    2006-06-01

    Transcriptional regulation in small genetic circuits exhibits large stochastic fluctuations. Recent experiments have shown that a significant fraction of these fluctuations is caused by extrinsic factors. In this paper we review several theoretical and computational approaches to modeling of small genetic circuits driven by extrinsic stochastic processes. We propose a simplified approach to this problem, which can be used in the case when extrinsic fluctuations dominate the stochastic dynamics of the circuit (as appears to be the case in eukaryots). This approach is applied to a model of a single nonregulated gene that is driven by a certain gating process that affects the rate of transcription, and to a simplified version of the galactose utilization circuit in yeast.

  2. Sparsity driven ultrasound imaginga)

    PubMed Central

    Tuysuzoglu, Ahmet; Kracht, Jonathan M.; Cleveland, Robin O.; C¸etin, Müjdat; Karl, W. Clem

    2012-01-01

    An image formation framework for ultrasound imaging from synthetic transducer arrays based on sparsity-driven regularization functionals using single-frequency Fourier domain data is proposed. The framework involves the use of a physics-based forward model of the ultrasound observation process, the formulation of image formation as the solution of an associated optimization problem, and the solution of that problem through efficient numerical algorithms. The sparsity-driven, model-based approach estimates a complex-valued reflectivity field and preserves physical features in the scene while suppressing spurious artifacts. It also provides robust reconstructions in the case of sparse and reduced observation apertures. The effectiveness of the proposed imaging strategy is demonstrated using experimental data. PMID:22352501

  3. Gas-driven microturbine

    SciTech Connect

    Sniegowski, J.J.; Rodgers, M.S.; McWhorter, P.J.; Aeschliman, D.P.; Miller, W.M.

    1996-06-27

    This paper describes an invention which relates to microtechnology and the fabrication process for developing microelectrical systems. It describes a means for fabricating a gas-driven microturbine capable of providing autonomous propulsion in which the rapidly moving gases are directed through a micromachined turbine to power devices by direct linkage or turbo-electric generators components in a domain ranging from tenths of micrometers to thousands of micrometers.

  4. Affinity driven social networks

    NASA Astrophysics Data System (ADS)

    Ruyú, B.; Kuperman, M. N.

    2007-04-01

    In this work we present a model for evolving networks, where the driven force is related to the social affinity between individuals of a population. In the model, a set of individuals initially arranged on a regular ordered network and thus linked with their closest neighbors are allowed to rearrange their connections according to a dynamics closely related to that of the stable marriage problem. We show that the behavior of some topological properties of the resulting networks follows a non trivial pattern.

  5. Data-Driven Objectness.

    PubMed

    Hongwen Kang; Hebert, Martial; Efros, Alexei A; Kanade, Takeo

    2015-01-01

    We propose a data-driven approach to estimate the likelihood that an image segment corresponds to a scene object (its "objectness") by comparing it to a large collection of example object regions. We demonstrate that when the application domain is known, for example, in our case activity of daily living (ADL), we can capture the regularity of the domain specific objects using millions of exemplar object regions. Our approach to estimating the objectness of an image region proceeds in two steps: 1) finding the exemplar regions that are the most similar to the input image segment; 2) calculating the objectness of the image segment by combining segment properties, mutual consistency across the nearest exemplar regions, and the prior probability of each exemplar region. In previous work, parametric objectness models were built from a small number of manually annotated objects regions, instead, our data-driven approach uses 5 million object regions along with their metadata information. Results on multiple data sets demonstrates our data-driven approach compared to the existing model based techniques. We also show the application of our approach in improving the performance of object discovery algorithms. PMID:26353218

  6. Driven superconducting quantum circuits

    NASA Astrophysics Data System (ADS)

    Nakamura, Yasunobu

    2014-03-01

    Driven nonlinear quantum systems show rich phenomena in various fields of physics. Among them, superconducting quantum circuits have very attractive features such as well-controlled quantum states with design flexibility, strong nonlinearity of Josephson junctions, strong coupling to electromagnetic driving fields, little internal dissipation, and tailored coupling to the electromagnetic environment. We have investigated properties and functionalities of driven superconducting quantum circuits. A transmon qubit coupled to a transmission line shows nearly perfect spatial mode matching between the incident and scattered microwave field in the 1D mode. Dressed states under a driving field are studied there and also in a semi-infinite 1D mode terminated by a resonator containing a flux qubit. An effective Λ-type three-level system is realized under an appropriate driving condition. It allows ``impedance-matched'' perfect absorption of incident probe photons and down conversion into another frequency mode. Finally, the weak signal from the qubit is read out using a Josephson parametric amplifier/oscillator which is another nonlinear circuit driven by a strong pump field. This work was partly supported by the Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST), Project for Developing Innovation Systems of MEXT, MEXT KAKENHI ``Quantum Cybernetics,'' and the NICT Commissioned Research.

  7. Chemically Driven Hydrodynamic Instabilities

    NASA Astrophysics Data System (ADS)

    Almarcha, C.; Trevelyan, P. M. J.; Grosfils, P.; de Wit, A.

    2010-01-01

    In the gravity field, density changes triggered by a kinetic scheme as simple as A+B→C can induce or affect buoyancy-driven instabilities at a horizontal interface between two solutions containing initially the scalars A and B. On the basis of a general reaction-diffusion-convection model, we analyze to what extent the reaction can destabilize otherwise buoyantly stable density stratifications. We furthermore show that, even if the underlying nonreactive system is buoyantly unstable, the reaction breaks the symmetry of the developing patterns. This is demonstrated both numerically and experimentally on the specific example of a simple acid-base neutralization reaction.

  8. System Driven Workarounds

    NASA Technical Reports Server (NTRS)

    Connell, Linda; Wichner, David; Jakey, Abegael Marie

    2013-01-01

    The Aviation Safety Reporting System (ASRS) in a partnership between the National Aeronautics and Space Administration (NASA), the Federal Aviation Administration (FAA), participating carriers, and labor organizations. It is designed to improve the National Airspace System by collecting and studying reports detailing unsafe conditions and events in the aviation industry. Employees are able to report safety issues or concerns with confidentiality and without fear of discipline. Safety reports highlighting system driven workarounds for the aviation community highlight the human workaround for the complex aviation system.

  9. Market Driven Space Exploration

    NASA Astrophysics Data System (ADS)

    Gavert, Raymond B.

    2004-02-01

    Market driven space exploration will have the opportunity to develop to new levels with the coming of space nuclear power and propulsion. NASA's recently established Prometheus program is expected to receive several billion dollars over the next five years for developing nuclear power and propulsion systems for future spacecraft. Not only is nuclear power and propulsion essential for long distance Jupiter type missions, but it also important for providing greater access to planets and bodies nearer to the Earth. NASA has been working with industrial partners since 1987 through its Research Partnerships Centers (RPCs) to utilize the attributes of space in Low Earth Orbit (LEO). Plans are now being made to utilize the RPCs and industrial partners in extending the duration and boundaries of human space flight to create new opportunities for exploration and discovery. Private investors are considering setting up shops in LEO for commercial purposes. The trend is for more industrial involvement in space. Nuclear power and propulsion will hasten the progress. The objective of this paper is to show the progression of space market driven research and its potential for supporting space exploration given nuclear power and propulsion capabilities.

  10. Heat driven pulse pump

    NASA Technical Reports Server (NTRS)

    Benner, Steve M (Inventor); Martins, Mario S. (Inventor)

    2000-01-01

    A heat driven pulse pump includes a chamber having an inlet port, an outlet port, two check valves, a wick, and a heater. The chamber may include a plurality of grooves inside wall of the chamber. When heated within the chamber, a liquid to be pumped vaporizes and creates pressure head that expels the liquid through the outlet port. As liquid separating means, the wick, disposed within the chamber, is to allow, when saturated with the liquid, the passage of only liquid being forced by the pressure head in the chamber, preventing the vapor from exiting from the chamber through the outlet port. A plurality of grooves along the inside surface wall of the chamber can sustain the liquid, which is amount enough to produce vapor for the pressure head in the chamber. With only two simple moving parts, two check valves, the heat driven pulse pump can effectively function over the long lifetimes without maintenance or replacement. For continuous flow of the liquid to be pumped a plurality of pumps may be connected in parallel.

  11. THERMALLY DRIVEN ATMOSPHERIC ESCAPE

    SciTech Connect

    Johnson, Robert E.

    2010-06-20

    Accurately determining the escape rate from a planet's atmosphere is critical for determining its evolution. A large amount of Cassini data is now available for Titan's upper atmosphere and a wealth of data is expected within the next decade on escape from Pluto, Mars, and extra-solar planets. Escape can be driven by upward thermal conduction of energy deposited well below the exobase, as well as by nonthermal processes produced by energy deposited in the exobase region. Recent applications of a model for escape driven by upward thermal conduction, called the slow hydrodynamic escape model, have resulted in surprisingly large loss rates for the atmosphere of Titan, Saturn's largest moon. Based on a molecular kinetic simulation of the exobase region, these rates appear to be orders of magnitude too large. Therefore, the slow hydrodynamic model is evaluated here. It is shown that such a model cannot give a reliable description of the atmospheric temperature profile unless it is coupled to a molecular kinetic description of the exobase region. Therefore, the present escape rates for Titan and Pluto must be re-evaluated using the atmospheric model described here.

  12. Steady Capillary Driven Flow

    NASA Technical Reports Server (NTRS)

    Weislogel, Mark M.

    1996-01-01

    A steady capillary driven flow is developed for a liquid index in a circular tube which is partially coated with a surface modifier to produce a discontinuous wetting condition from one side of the tube to the other. The bulk flow is novel in that it is truly steady, and controlled solely by the physics associated with dynamic wetting. The influence of gravity on the flow is minimized through the use of small diameter tubes approximately O(1 mm) tested horizontally in a laboratory and larger tubes approximately O(10 mm) tested in the low gravity environment of a drop tower. Average steady velocities are predicted and compared against a large experimental data set which includes the effects of tube dimensions and fluid properties. The sensitivity of the velocity to surface cleanliness is dramatic and the advantages of experimentation in a microgravity environment are discussed.

  13. Qplus AFM driven nanostencil.

    PubMed

    Grévin, B; Fakir, M; Hayton, J; Brun, M; Demadrille, R; Faure-Vincent, J

    2011-06-01

    We describe the development of a novel setup, in which large stencils with suspended silicon nitride membranes are combined with atomic force microscopy (AFM) regulation by using tuning forks. This system offers the possibility to perform separate AFM and nanostencil operations, as well as combined modes when using stencil chips with integrated tips. The flexibility and performances are demonstrated through a series of examples, including wide AFM scans in closed loop mode, probe positioning repeatability of a few tens of nanometer, simultaneous evaporation of large (several hundred of micron square) and nanoscopic metals and fullerene patterns in static, multistep, and dynamic modes. This approach paves the way for further developments, as it fully combines the advantages of conventional stenciling with the ones of an AFM driven shadow mask. PMID:21721701

  14. Muscle-driven nanogenerators

    DOEpatents

    Wang, Zhong L.; Yang, Rusen

    2011-03-01

    In a method of generating electricity, a plurality of living cells are grown on an array of piezoelectric nanowires so that the cells engage the piezoelectric nanowires. Induced static potentials are extracted from at least one of the piezoelectric nanowires when at least one of the cells deforms the at least one of the piezoelectric nanowires. A cell-driven electrical generator that includes a substrate and a plurality of spaced-apart piezoelectric nanowires disposed on the substrate. A plurality of spaced-apart conductive electrodes interact with the plurality of piezoelectric nanowires. A biological buffer layer that is configured to promote growth of cells is disposed on the substrate so that cells placed on the substrate will grow and engage the piezoelectric nanowires.

  15. Soliton driven angiogenesis

    PubMed Central

    Bonilla, L. L.; Carretero, M.; Terragni, F.; Birnir, B.

    2016-01-01

    Angiogenesis is a multiscale process by which blood vessels grow from existing ones and carry oxygen to distant organs. Angiogenesis is essential for normal organ growth and wounded tissue repair but it may also be induced by tumours to amplify their own growth. Mathematical and computational models contribute to understanding angiogenesis and developing anti-angiogenic drugs, but most work only involves numerical simulations and analysis has lagged. A recent stochastic model of tumour-induced angiogenesis including blood vessel branching, elongation, and anastomosis captures some of its intrinsic multiscale structures, yet allows one to extract a deterministic integropartial differential description of the vessel tip density. Here we find that the latter advances chemotactically towards the tumour driven by a soliton (similar to the famous Korteweg-de Vries soliton) whose shape and velocity change slowly. Analysing these collective coordinates paves the way for controlling angiogenesis through the soliton, the engine that drives this process. PMID:27503562

  16. Soliton driven angiogenesis

    NASA Astrophysics Data System (ADS)

    Bonilla, L. L.; Carretero, M.; Terragni, F.; Birnir, B.

    2016-08-01

    Angiogenesis is a multiscale process by which blood vessels grow from existing ones and carry oxygen to distant organs. Angiogenesis is essential for normal organ growth and wounded tissue repair but it may also be induced by tumours to amplify their own growth. Mathematical and computational models contribute to understanding angiogenesis and developing anti-angiogenic drugs, but most work only involves numerical simulations and analysis has lagged. A recent stochastic model of tumour-induced angiogenesis including blood vessel branching, elongation, and anastomosis captures some of its intrinsic multiscale structures, yet allows one to extract a deterministic integropartial differential description of the vessel tip density. Here we find that the latter advances chemotactically towards the tumour driven by a soliton (similar to the famous Korteweg-de Vries soliton) whose shape and velocity change slowly. Analysing these collective coordinates paves the way for controlling angiogenesis through the soliton, the engine that drives this process.

  17. Consistent model driven architecture

    NASA Astrophysics Data System (ADS)

    Niepostyn, Stanisław J.

    2015-09-01

    The goal of the MDA is to produce software systems from abstract models in a way where human interaction is restricted to a minimum. These abstract models are based on the UML language. However, the semantics of UML models is defined in a natural language. Subsequently the verification of consistency of these diagrams is needed in order to identify errors in requirements at the early stage of the development process. The verification of consistency is difficult due to a semi-formal nature of UML diagrams. We propose automatic verification of consistency of the series of UML diagrams originating from abstract models implemented with our consistency rules. This Consistent Model Driven Architecture approach enables us to generate automatically complete workflow applications from consistent and complete models developed from abstract models (e.g. Business Context Diagram). Therefore, our method can be used to check practicability (feasibility) of software architecture models.

  18. Soliton driven angiogenesis.

    PubMed

    Bonilla, L L; Carretero, M; Terragni, F; Birnir, B

    2016-01-01

    Angiogenesis is a multiscale process by which blood vessels grow from existing ones and carry oxygen to distant organs. Angiogenesis is essential for normal organ growth and wounded tissue repair but it may also be induced by tumours to amplify their own growth. Mathematical and computational models contribute to understanding angiogenesis and developing anti-angiogenic drugs, but most work only involves numerical simulations and analysis has lagged. A recent stochastic model of tumour-induced angiogenesis including blood vessel branching, elongation, and anastomosis captures some of its intrinsic multiscale structures, yet allows one to extract a deterministic integropartial differential description of the vessel tip density. Here we find that the latter advances chemotactically towards the tumour driven by a soliton (similar to the famous Korteweg-de Vries soliton) whose shape and velocity change slowly. Analysing these collective coordinates paves the way for controlling angiogenesis through the soliton, the engine that drives this process. PMID:27503562

  19. Fluid driven reciprocating apparatus

    DOEpatents

    Whitehead, J.C.

    1997-04-01

    An apparatus is described comprising a pair of fluid driven pump assemblies in a back-to-back configuration to yield a bi-directional pump. Each of the pump assemblies includes a piston or diaphragm which divides a chamber therein to define a power section and a pumping section. An intake-exhaust valve is connected to each of the power sections of the pump chambers, and function to direct fluid, such as compressed air, into the power section and exhaust fluid therefrom. At least one of the pistons or diaphragms is connected by a rod assembly which is constructed to define a signal valve, whereby the intake-exhaust valve of one pump assembly is controlled by the position or location of the piston or diaphragm in the other pump assembly through the operation of the rod assembly signal valve. Each of the pumping sections of the pump assemblies are provided with intake and exhaust valves to enable filling of the pumping section with fluid and discharging fluid therefrom when a desired pressure has been reached. 13 figs.

  20. Compositionally Driven Dynamos

    NASA Astrophysics Data System (ADS)

    Soderlund, K. M.; Schubert, G.

    2014-12-01

    It is generally believed that compositional convection driven by inner core solidification is the main driver of the geodynamo. Thermal evolution considerations make it likely that compositional convection is also behind the present dynamos of Mercury and Ganymede as well as the early dynamos in the Moon, Mars and smaller solar system bodies. Compositional buoyancy can arise in several different ways, for example, through inner core solidification and FeS flotation with upward mixing and through freezing out and sinking of iron snow near the core-mantle boundary or deeper within the core. The mode of core cooling and freezing depends on conditions of temperature and pressure in the core and the concentration of light elements such as sulfur. Different distributions of compositional buoyancy will give rise to different patterns of core convection and dynamo magnetic fields. We report here the first results of a systematic study of the distribution of compositional buoyancy on the dynamo-generated magnetic fields, with an emphasis on Mars' core evolution due to iron rain.

  1. Fluid driven recipricating apparatus

    DOEpatents

    Whitehead, John C.

    1997-01-01

    An apparatus comprising a pair of fluid driven pump assemblies in a back-to-back configuration to yield a bi-directional pump. Each of the pump assemblies includes a piston or diaphragm which divides a chamber therein to define a power section and a pumping section. An intake-exhaust valve is connected to each of the power sections of the pump chambers, and function to direct fluid, such as compressed air, into the power section and exhaust fluid therefrom. At least one of the pistons or diaphragms is connected by a rod assembly which is constructed to define a signal valve, whereby the intake-exhaust valve of one pump assembly is controlled by the position or location of the piston or diaphragm in the other pump assembly through the operation of the rod assembly signal valve. Each of the pumping sections of the pump assemblies are provided with intake and exhaust valves to enable filling of the pumping section with fluid and discharging fluid therefrom when a desired pressure has been reached.

  2. Invention-driven marketing

    NASA Technical Reports Server (NTRS)

    Carlson, William E.

    1994-01-01

    Suppose you have just created a revolutionary bicycle suspension which allows a bike to be ridden over rough terrain at 60 miles per hour. In addition, suppose that you are deeply concerned about the plight of hungry children. Which should you do: be sure all hungry children have bicycles; transfer the technology for your new suspension to bicycle manufacturers worldwide; or start a company to supply premium sports bicycle based on your patented technology, and donate the profits to a charity which feeds hungry children? Woven through this somewhat trivial example is the paradox of technology transfer - the supplier (owner) may want to transfer technology; but to succeed, he or she must reformulate the problem as a user need for which there is a new and better solution. Successful technology transfer is little more than good marketing applied to an existing invention, process, or capability. You must identify who needs the technology, why they need it, why the new technology is better than alternatives, how much the customers are willing and able to pay for these benefits, and how to distribute products based on the technology tc the target customers. In market-driven development, the term 'technology transfer' is rarely used. The developers focus on studying user needs and designing solution They may have technology needs, but they don't have technology in search of a use.

  3. Wind driven air pump

    SciTech Connect

    Beisel, V.A.

    1983-05-31

    An improved pump for lifting water from an underground source utilizes a wind motor for driving an oil-less air compressor eliminating oil contamination of ground water which is forced to the surface. The wind motor is movable to face the wind by means of a novel swivel assembly which also eliminates the formation and freezing of condensate within the airline from the compressor. The propeller blades of the wind motor and the tail section are formed from a pair of opposed convex air foil shaped surfaces which provide the propeller blades and the tail section with fast sensitivity to slight changes in wind direction and speed. A novel well tower for supporting the wind motor and compressor and for lifting the water from the underground source is an optional modification which requires no welding and eliminates the problem of condensate freezing in the airline going to the well. The wind driven air pump disclosed is lightweight, can be easily installed, is relatively inexpensive to produce and is virtually maintenance-free and capable of operating in winds exceeding 100 miles per hour.

  4. Salinity driven oceanographic upwelling

    DOEpatents

    Johnson, David H.

    1986-01-01

    The salinity driven oceanographic upwelling is maintained in a mariculture device that includes a long main duct in the general shape of a cylinder having perforated cover plates at each end. The mariculture device is suspended vertically in the ocean such that one end of the main duct is in surface water and the other end in relatively deep water that is cold, nutrient rich and relatively fresh in comparison to the surface water which is relatively warm, relatively nutrient deficient and relatively saline. A plurality of elongated flow segregating tubes are disposed in the main duct and extend from the upper cover plate beyond the lower cover plate into a lower manifold plate. The lower manifold plate is spaced from the lower cover plate to define a deep water fluid flow path to the interior space of the main duct. Spacer tubes extend from the upper cover plate and communicate with the interior space of the main duct. The spacer tubes are received in an upper manifold plate spaced from the upper cover plate to define a surface water fluid flow path into the flow segregating tubes. A surface water-deep water counterflow is thus established with deep water flowing upwardly through the main duct interior for discharge beyond the upper manifold plate while surface water flows downwardly through the flow segregating tubes for discharge below the lower manifold plate. During such counterflow heat is transferred from the downflowing warm water to the upflowing cold water. The flow is maintained by the difference in density between the deep water and the surface water due to their differences in salinity. The upwelling of nutrient rich deep water is used for marifarming by fertilizing the nutrient deficient surface water.

  5. Salinity driven oceanographic upwelling

    DOEpatents

    Johnson, D.H.

    1984-08-30

    The salinity driven oceanographic upwelling is maintained in a mariculture device that includes a long main duct in the general shape of a cylinder having perforated cover plates at each end. The mariculture device is suspended vertically in the ocean such that one end of the main duct is in surface water and the other end in relatively deep water that is cold, nutrient rich and relatively fresh in comparison to the surface water which is relatively warm, relatively nutrient deficient and relatively saline. A plurality of elongated flow segregating tubes are disposed in the main duct and extend from the upper cover plate beyond the lower cover plate into a lower manifold plate. The lower manifold plate is spaced from the lower cover plate to define a deep water fluid flow path to the interior space of the main duct. Spacer tubes extend from the upper cover plate and communicate with the interior space of the main duct. The spacer tubes are received in an upper manifold plate spaced from the upper cover plate to define a surface water fluid flow path into the flow segregating tubes. A surface water-deep water counterflow is thus established with deep water flowing upwardly through the main duct interior for discharge beyond the upper manifold plate while surface water flows downwardly through the flow segregating tubes for discharge below the lower manifold plate. During such counterflow heat is transferred from the downflowing warm water to the upflowing cold water. The flow is maintained by the difference in density between the deep water and the surface water due to their differences in salinity. The upwelling of nutrient rich deep water is used for marifarming by fertilizing the nutrient deficient surface water. 1 fig.

  6. Comments on event driven animation

    NASA Technical Reports Server (NTRS)

    Gomez, Julian E.

    1987-01-01

    Event driven animation provides a general method of describing controlling values for various computer animation techniques. A definition and comments are provided on genralizing motion description with events. Additional comments are also provided about the implementation of twixt.

  7. Data-driven batch schuduling

    SciTech Connect

    Bent, John; Denehy, Tim; Arpaci - Dusseau, Remzi; Livny, Miron; Arpaci - Dusseau, Andrea C

    2009-01-01

    In this paper, we develop data-driven strategies for batch computing schedulers. Current CPU-centric batch schedulers ignore the data needs within workloads and execute them by linking them transparently and directly to their needed data. When scheduled on remote computational resources, this elegant solution of direct data access can incur an order of magnitude performance penalty for data-intensive workloads. Adding data-awareness to batch schedulers allows a careful coordination of data and CPU allocation thereby reducing the cost of remote execution. We offer here new techniques by which batch schedulers can become data-driven. Such systems can use our analytical predictive models to select one of the four data-driven scheduling policies that we have created. Through simulation, we demonstrate the accuracy of our predictive models and show how they can reduce time to completion for some workloads by as much as 80%.

  8. Magnetically driven quantum heat engine.

    PubMed

    Muñoz, Enrique; Peña, Francisco J

    2014-05-01

    We studied the efficiency of two different schemes for a magnetically driven quantum heat engine, by considering as the "working substance" a single nonrelativistic particle trapped in a cylindrical potential well, in the presence of an external magnetic field. The first scheme is a cycle, composed of two adiabatic and two isoenergetic reversible trajectories in configuration space. The trajectories are driven by a quasistatic modulation of the external magnetic-field intensity. The second scheme is a variant of the former, where the isoenergetic trajectories are replaced by isothermal ones, along which the system is in contact with macroscopic thermostats. This second scheme constitutes a quantum analog of the classical Carnot cycle.

  9. Capillary-driven microfluidic chips with evaporation-induced flow control and dielectrophoretic microbead trapping

    NASA Astrophysics Data System (ADS)

    Temiz, Yuksel; Skorucak, Jelena; Delamarche, Emmanuel

    2014-07-01

    This work reports our efforts on developing simple-to-use microfluidic devices for point-of-care diagnostic applications with recent extensions that include the trapping of microbeads using dielectrophoresis (DEP) and the modulation of the liquid flow using integrated microheaters. DEP serves the purpose of trapping microbeads coated with receptors and analytes for detection of a fluorescent signal. The microheater is actuated once the chip is filled by capillarity, creating an evaporation-induced flow tuned according to assay conditions. The chips are composed of a glass substrate patterned with 50-nm-thick Pd electrodes and microfluidic structures made using a 20-μm-thick dry-film resist (DFR). Chips are covered/sealed by low temperature (50°C) lamination of a 50-μm-thick DFR layer having excellent optical and mechanical properties. To separate cleaned and sealed chips from the wafer, we used an effective chip singulation technique which we informally call the "chip-olate" process. In the experimental section, we first studied dielectrophoretic trapping of 10-μm beads for flow rates ranging from 80 pL s-1 to 2.5 nL s-1 that are generated by an external syringe pump. Then, we characterized the embedded microheater in DFR-covered chips. Flow rates as high as 8 nL s-1 were generated by evaporation-induced flow when the heater was biased by 10 V, corresponding to 270-mW power. Finally, DEP-based trapping and fluorescent detection of functionalized beads were demonstrated as the flow was generated by evaporation-induced flow after the microfluidic structures were filled by capillarity.

  10. Pattern Formation in Driven Systems

    NASA Astrophysics Data System (ADS)

    Klymko, Katherine

    Model colloidal particles of two types, driven in opposite directions, will in two dimensions segregate into lanes, a phenomenon studied extensively by Lowen and co-workers [Dzubiella et al. Phys. Rev. E 65, 021402 (2002)]. We have simulated mixtures of oppositely-driven particles using three numerical protocols. We find that laning results from enhanced diffusion, in the direction perpendicular to the drive, of particles surrounded by particles of the opposite type, consistent with the observation of Vissers et al. [Soft Matter 7, 6, 2352 (2011)]. By comparing protocols we find that enhanced diffusion follows from a simple geometrical constraint: oppositely-driven particles must, in the time taken to encounter each other in the direction of the drive, diffuse in the perpendicular direction by about one particle diameter. This constraint implies that the effective lateral diffusion constant grows linearly with drive speed and as the square root of the packing fraction, a prediction supported by our numerics. By invoking an analogy between hard particles with environment-dependent mobilities and mutually attractive particles we argue that there exists an equilibrium system whose pattern-forming properties are similar to those of the driven system. Katherine Klymko acknowledges support from the NSF Graduate Research Fellowship.

  11. Driven shielding capacitive proximity sensor

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor); McConnell, Robert L. (Inventor)

    2000-01-01

    A capacitive proximity sensing element, backed by a reflector driven at the same voltage as and in phase with the sensor, is used to reflect the field lines away from a grounded robot arm towards an intruding object, thus dramatically increasing the sensor's range and sensitivity.

  12. Data-Driven Proficiency Profiling

    ERIC Educational Resources Information Center

    Mostafavi, Behrooz; Liu, Zhongxiu; Barnes, Tiffany

    2015-01-01

    Deep Thought is a logic tutor where students practice constructing deductive logic proofs. Within Deep Thought is a data-driven mastery learning system (DDML), which calculates student proficiency based on rule scores weighted by expert-decided weights in order to assign problem sets of appropriate difficulty. In this study, we designed and tested…

  13. Parasitic driven heliostat mirror declinator

    SciTech Connect

    Rhodes, W.A.

    1983-09-06

    An automatic parasitically driven declinator is disclosed for changing the tilt angle of the mirror of a heliostat to provide solar declination tracking by the heliostat. The declinator includes an axial gear drive train coupled to the polar axial shaft of the heliostat, which shaft is rotated. A pendulum arrangement coupled via an input shaft to the axial gear drive train is substantially held in plumb position by gravity wherein the gear drive train is driven as it is rotated about the polar axis by the polar axial shaft. An output shaft coupled to the gear train is rotated to drive a skew bar linkage assembly that is connected to the mirror mounting assembly of the heliostat. The gear ratio of the gear drive train assembly is made 365:1 so that the mirror angle is annually nutated a predetermined number of degrees corresponding to the cyclic variations of solar declination.

  14. Electrically driven environmental control system

    SciTech Connect

    Mcnamara, J.E.

    1984-05-01

    An environmental control system (ECS) being developed under the title of energy efficient environmental control system is described. The ECS is a closed-loop, electrically driven, vapor cycle system. The vapor cycle will have a compressor driven by a variable speed, high-voltage dc motor. The reasons for selecting this type of system are discussed here. Breadboard testing of a variable speed compressor to demonstrate the feasibility of such an approach has been completed. The testing results were used to develop a preliminary design of a prototype compressor. In future phases of the program, the prototype compressor will be developed a prototype system will be constructed and laboratory tested and finally the prototype system will be flight demonstrated.

  15. Pulsed Power Driven Fusion Energy

    SciTech Connect

    SLUTZ,STEPHEN A.

    1999-11-22

    Pulsed power is a robust and inexpensive technology for obtaining high powers. Considerable progress has been made on developing light ion beams as a means of transporting this power to inertial fusion capsules. However, further progress is hampered by the lack of an adequate ion source. Alternatively, z-pinches can efficiently convert pulsed power into thermal radiation, which can be used to drive an inertial fusion capsule. However, a z-pinch driven fusion explosion will destroy a portion of the transmission line that delivers the electrical power to the z-pinch. They investigate several options for providing standoff for z-pinch driven fusion. Recyclable Transmission Lines (RTLs) appear to be the most promising approach.

  16. Kaehler-driven tribrid inflation

    SciTech Connect

    Antusch, Stefan; Nolde, David E-mail: david.nolde@unibas.ch

    2012-11-01

    We discuss a new class of tribrid inflation models in supergravity, where the shape of the inflaton potential is dominated by effects from the Kaehler potential. Tribrid inflation is a variant of hybrid inflation which is particularly suited for connecting inflation with particle physics, since the inflaton can be a D-flat combination of charged fields from the matter sector. In models of tribrid inflation studied so far, the inflaton potential was dominated by either loop corrections or by mixing effects with the waterfall field (as in 'pseudosmooth' tribrid inflation). Here we investigate the third possibility, namely that tribrid inflation is dominantly driven by effects from higher-dimensional operators of the Kaehler potential. We specify for which superpotential parameters the new regime is realized and show how it can be experimentally distinguished from the other two (loop-driven and {sup p}seudosmooth{sup )} regimes.

  17. Heterogeneity in motor driven transport

    NASA Astrophysics Data System (ADS)

    Tabei, Ali

    2015-03-01

    I will discuss quantitative analysis of particle tracking data for motor driven vesicles inside an insulin secreting cell. We use this method to study the dynamical and structural heterogeneity inside the cell. I will discuss our effort to explain the origin of observed heterogeneity in intracellular transport. Finally, I will explain how analyzing directional correlations in transport trajectories reveals self-similarity in the diffusion media.

  18. Mission Driven Science at Argonne

    SciTech Connect

    Thackery, Michael; Wang, Michael; Young, Linda

    2012-01-01

    Mission driven science at Argonne means applying science and scientific knowledge to a physical and "real world" environment. Examples include testing a theoretical model through the use of formal science or solving a practical problem through the use of natural science. At the laboratory, our materials scientists are leading the way in producing energy solutions today that could help reduce and remove the energy crisis of tomorrow.

  19. Kinetics of accelerator driven devices

    SciTech Connect

    Perry, R.T.; Buksa, J.; Houts, M.

    1994-09-01

    Kinetic calculations were made to show that subcritical accelerator driven devices are robust and stable. The calculations show that large changes in reactivity that would lead to an uncontrollable excursion in a reactor would lead only to a new power level in subcritical device. Calculations were also made to show the rate of power changes resulting from startup and shutdown, and that methods also exist for continuously monitoring the reactivity of a subcritical system.

  20. Active and driven hydrodynamic crystals.

    PubMed

    Desreumaux, N; Florent, N; Lauga, E; Bartolo, D

    2012-08-01

    Motivated by the experimental ability to produce monodisperse particles in microfluidic devices, we study theoretically the hydrodynamic stability of driven and active crystals. We first recall the theoretical tools allowing to quantify the dynamics of elongated particles in a confined fluid. In this regime hydrodynamic interactions between particles arise from a superposition of potential dipolar singularities. We exploit this feature to derive the equations of motion for the particle positions and orientations. After showing that all five planar Bravais lattices are stationary solutions of the equations of motion, we consider separately the case where the particles are passively driven by an external force, and the situation where they are self-propelling. We first demonstrate that phonon modes propagate in driven crystals, which are always marginally stable. The spatial structures of the eigenmodes depend solely on the symmetries of the lattices, and on the orientation of the driving force. For active crystals, the stability of the particle positions and orientations depends not only on the symmetry of the crystals but also on the perturbation wavelengths and on the crystal density. Unlike unconfined fluids, the stability of active crystals is independent of the nature of the propulsion mechanism at the single-particle level. The square and rectangular lattices are found to be linearly unstable at short wavelengths provided the volume fraction of the crystals is high enough. Differently, hexagonal, oblique, and face-centered crystals are always unstable. Our work provides a theoretical basis for future experimental work on flowing microfluidic crystals. PMID:22864543

  1. Edge-driven microplate kinematics

    USGS Publications Warehouse

    Schouten, Hans; Klitgord, Kim D.; Gallo, David G.

    1993-01-01

    It is known from plate tectonic reconstructions that oceanic microplates undergo rapid rotation about a vertical axis and that the instantaneous rotation axes describing the microplate's motion relative to the bounding major plates are frequently located close to its margins with those plates, close to the tips of propagating rifts. We propose a class of edge-driven block models to illustrate how slip across the microplate margins, block rotation, and propagation of rifting may be related to the relative motion of the plates on either side. An important feature of these edge-driven models is that the instantaneous rotation axes are always located on the margins between block and two bounding plates. According to those models the pseudofaults or traces of disrupted seafloor resulting from the propagation of rifting between microplate and major plates may be used independently to approximately trace the continuous kinematic evolution of the microplate back in time. Pseudofault geometries and matching rotations of the Easter microplate show that for most of its 5 m.y. history, block rotation could be driven by the drag of the Nazca and Pacific plates on the microplate's edges rather than by a shear flow of mantle underneath.

  2. Wind driven power generating apparatus

    SciTech Connect

    Andruszkiw, W.; Andrushkiw, R.

    1986-10-14

    A vertically adjustable wind driven power generating apparatus comprised of, in combination, a well in which is vertically movably mounted a wind driven power generating apparatus comprised of: (i) a wind driven power generating means comprised of a tubular housing having rotatably mounted therein a horizontally extending shaft. The shaft has a centrally disposed bevel gear fixedly attached thereto and helical vanes disposed longitudinally on both sides of the bevel gear; (ii) means for vertical movement of the tubular housing within the well comprised of (a) a hollow vertical support column having a circular cross section and having one end thereof attached to the bottom of the tubular housing and (b) a vertically extending hollow tubular member having a hollow interior fixedly mounted at its bottom end in the floor of the well and being open at its other end, the tubular member adapted to telescopically receive the vertical support column in its open end; (iii) vertical movement control means comprised of (a) downward movement control means comprising an inverted wing system generating inverse-lift mounted on the tubular housing, and (b) upward movement control means comprising a cylinder having an axially movable piston therein; (iv) power transmission means comprising a vertically extending power transmitting shaft that drives a power generator.

  3. The Myths of Data-Driven Schools

    ERIC Educational Resources Information Center

    Jones, Alan

    2005-01-01

    The most recent attempt by educators to emulate the "sound principles" and methods of business and science is to become data-driven. The leaders in a data-driven school are able to demonstrate how some number, preferably scores on standardized tests, has moved upward as a result of some program they have initiated. Data-driven schools also possess…

  4. Is "Market-Driven" Good Enough?

    ERIC Educational Resources Information Center

    Kaufman, Roger

    1995-01-01

    Discusses marketing and management strategies and evaluates the path most traveled; going beyond market-driven; proactive and reactive organizational positioning; ways to manage human and physical resources to make both market-driven and market-making contributions; and values necessary for an organization to move from market-driven to…

  5. Preferential enhancement of laser-driven carbon ion acceleration from optimized nanostructured surfaces

    PubMed Central

    Dalui, Malay; Wang, W.-M.; Trivikram, T. Madhu; Sarkar, Subhrangshu; Tata, Sheroy; Jha, J.; Ayyub, P.; Sheng, Z. M.; Krishnamurthy, M.

    2015-01-01

    High-intensity ultrashort laser pulses focused on metal targets readily generate hot dense plasmas which accelerate ions efficiently and can pave way to compact table-top accelerators. Laser-driven ion acceleration studies predominantly focus on protons, which experience the maximum acceleration owing to their highest charge-to-mass ratio. The possibility of tailoring such schemes for the preferential acceleration of a particular ion species is very much desired but has hardly been explored. Here, we present an experimental demonstration of how the nanostructuring of a copper target can be optimized for enhanced carbon ion acceleration over protons or Cu-ions. Specifically, a thin (≈0.25 μm) layer of 25–30 nm diameter Cu nanoparticles, sputter-deposited on a polished Cu-substrate, enhances the carbon ion energy by about 10-fold at a laser intensity of 1.2×1018  W/cm2. However, particles smaller than 20 nm have an adverse effect on the ion acceleration. Particle-in-cell simulations provide definite pointers regarding the size of nanoparticles necessary for maximizing the ion acceleration. The inherent contrast of the laser pulse is found to play an important role in the species selective ion acceleration. PMID:26153048

  6. Preferential enhancement of laser-driven carbon ion acceleration from optimized nanostructured surfaces.

    PubMed

    Dalui, Malay; Wang, W-M; Trivikram, T Madhu; Sarkar, Subhrangsu; Sarkar, Subhrangshu; Tata, Sheroy; Jha, J; Ayyub, P; Sheng, Z M; Krishnamurthy, M

    2015-01-01

    High-intensity ultrashort laser pulses focused on metal targets readily generate hot dense plasmas which accelerate ions efficiently and can pave way to compact table-top accelerators. Laser-driven ion acceleration studies predominantly focus on protons, which experience the maximum acceleration owing to their highest charge-to-mass ratio. The possibility of tailoring such schemes for the preferential acceleration of a particular ion species is very much desired but has hardly been explored. Here, we present an experimental demonstration of how the nanostructuring of a copper target can be optimized for enhanced carbon ion acceleration over protons or Cu-ions. Specifically, a thin (≈ 0.25 μm) layer of 25-30 nm diameter Cu nanoparticles, sputter-deposited on a polished Cu-substrate, enhances the carbon ion energy by about 10-fold at a laser intensity of 1.2 × 10(18)  W/cm(2). However, particles smaller than 20 nm have an adverse effect on the ion acceleration. Particle-in-cell simulations provide definite pointers regarding the size of nanoparticles necessary for maximizing the ion acceleration. The inherent contrast of the laser pulse is found to play an important role in the species selective ion acceleration. PMID:26153048

  7. Patellofemoral syndrome: diagnostic pointers and individualized treatment.

    PubMed

    Labotz, Michele

    2004-07-01

    Most patients who have patellofemoral syndrome can be successfully treated once contributing factors are identified during history taking and physical examination. After pain and inflammation are treated, patients are encouraged to start activities that do not provoke pain. Exercise programs should be implemented that address underlying strength and flexibility deficits. Return to play primarily relies on advancement of pain-free activity, with some allowance for patients' competitive goals. Patients remaining symptomatic after compliance with a structured rehabilitation program or those with indicators of other intra-articular pathology should be referred to an orthopedist. PMID:20086418

  8. Catastrophe-driven vs what?

    SciTech Connect

    Stever, H.G.

    1995-12-31

    The author notes that much has been accomplished by catastrophe-driven scientific effort. Examples include World War II and the social wars against crime, poverty and hunger and famine. A positive approach is suggested to be more appropriate as the drivers of science. Three tables are presented and outline a positive base for justifying scientific endeavor: (1) Examples of Major Societal Goals to Which Science and Technology Contribute. (2) Policy Areas That Would Benefit from the Articulation of Long-Term S&T Goals; and (3) Major Components of the Science and Technology Base.

  9. Actively driven thermal radiation shield

    DOEpatents

    Madden, Norman W.; Cork, Christopher P.; Becker, John A.; Knapp, David A.

    2002-01-01

    A thermal radiation shield for cooled portable gamma-ray spectrometers. The thermal radiation shield is located intermediate the vacuum enclosure and detector enclosure, is actively driven, and is useful in reducing the heat load to mechanical cooler and additionally extends the lifetime of the mechanical cooler. The thermal shield is electrically-powered and is particularly useful for portable solid-state gamma-ray detectors or spectrometers that dramatically reduces the cooling power requirements. For example, the operating shield at 260K (40K below room temperature) will decrease the thermal radiation load to the detector by 50%, which makes possible portable battery operation for a mechanically cooled Ge spectrometer.

  10. Ontology-Driven Information Integration

    NASA Technical Reports Server (NTRS)

    Tissot, Florence; Menzel, Chris

    2005-01-01

    Ontology-driven information integration (ODII) is a method of computerized, automated sharing of information among specialists who have expertise in different domains and who are members of subdivisions of a large, complex enterprise (e.g., an engineering project, a government agency, or a business). In ODII, one uses rigorous mathematical techniques to develop computational models of engineering and/or business information and processes. These models are then used to develop software tools that support the reliable processing and exchange of information among the subdivisions of this enterprise or between this enterprise and other enterprises.

  11. Assessing respondent-driven sampling.

    PubMed

    Goel, Sharad; Salganik, Matthew J

    2010-04-13

    Respondent-driven sampling (RDS) is a network-based technique for estimating traits in hard-to-reach populations, for example, the prevalence of HIV among drug injectors. In recent years RDS has been used in more than 120 studies in more than 20 countries and by leading public health organizations, including the Centers for Disease Control and Prevention in the United States. Despite the widespread use and growing popularity of RDS, there has been little empirical validation of the methodology. Here we investigate the performance of RDS by simulating sampling from 85 known, network populations. Across a variety of traits we find that RDS is substantially less accurate than generally acknowledged and that reported RDS confidence intervals are misleadingly narrow. Moreover, because we model a best-case scenario in which the theoretical RDS sampling assumptions hold exactly, it is unlikely that RDS performs any better in practice than in our simulations. Notably, the poor performance of RDS is driven not by the bias but by the high variance of estimates, a possibility that had been largely overlooked in the RDS literature. Given the consistency of our results across networks and our generous sampling conditions, we conclude that RDS as currently practiced may not be suitable for key aspects of public health surveillance where it is now extensively applied. PMID:20351258

  12. Piezoelectrically-driven Thermoacoustic Refrigerator

    NASA Astrophysics Data System (ADS)

    Chinn, Daniel George

    Thermoacoustic refrigeration is an emerging refrigeration technology which does not require any moving parts or harmful refrigerants in its operation. This technology uses acoustic waves to pump heat across a temperature gradient. The vast majority of thermoacoustic refrigerators to date have used electromagnetic loudspeakers to generate the acoustic input. In this thesis, the design, construction, operation, and modeling of a piezoelectrically-driven thermoacoustic refrigerator are detailed. This refrigerator demonstrates the effectiveness of piezoelectric actuation in moving 0.3 W of heat across an 18 degree C temperature difference with an input power of 7.6 W. The performance characteristics of this class of thermoacoustic-piezoelectric refrigerators are modeled by using DeltaEC software and the predictions are experimentally validated. The obtained results confirm the validity of the developed model. Furthermore, the potential of piezoelectric actuation as effective means for driving thermoacoustic refrigerators is demonstrated as compared to the conventional electromagnetic loudspeakers which are heavy and require high actuation energy. The developed theoretical and experimental tools can serve as invaluable means for the design and testing of other piezoelectrically-driven thermoacoustic refrigerator configurations.

  13. Magnetically driven quantum heat engine

    NASA Astrophysics Data System (ADS)

    Munoz, Enrique; Pena, Francisco

    2015-03-01

    In analogy with classical thermodynamics, a quantum heat engine generates useful mechanical work from heat, by means of a reversible sequence of transformations (trajectories), where the ``working substance'' is of quantum mechanical nature. Several theoretical implementations for a quantum heat engine have been discussed in the literature, such as entangled states in a qubit, quantum mechanical versions of the Otto cycle, and photocells. In this work, we propose yet a different alternative by introducing the concept of a magnetically driven quantum heat engine. We studied the efficiency of such system, by considering as the ``working substance'' a single nonrelativistic particle trapped in a cylindrical potential well, as a model for a semiconductor quantum dot, in the presence of an external magnetic field. The trajectories are driven by a quasistatic modulation of the external magnetic-field intensity, while the system is in contact with macroscopic thermostats. The external magnetic field modulation allows to modify the effective geometric confinement, in analogy with a piston in a classical gas. E. Munoz acknowledges financial support from Fondecyt under Contract 1141146.

  14. Investigating Reaction-Driven Cracking

    NASA Astrophysics Data System (ADS)

    Kelemen, P. B.; Hirth, G.; Savage, H. M.

    2013-12-01

    Many metamorphic reactions lead to large volume changes, and potentially to reaction-driven cracking [1,2]. Large-scale hydration of mantle peridotite to produce serpentine or talc is invoked to explain the rheology of plate boundaries, the nature of earthquakes, and the seismic properties of slow-spread ocean crust and the 'mantle wedge' above subduction zones. Carbonation of peridotite may be an important sink in the global carbon cycle. Zones of 100% magnesite + quartz replacing peridotite, up to 200 m thick, formed where oceanic mantle was thrust over carbonate-bearing metasediments in Oman. Talc + carbonate is an important component of the matrix in subduction mélanges at Santa Catalina Island , California, and the Sanbagawa metamorphic belt, Japan. Engineered systems to emulate natural mineral carbonation could provide relatively inexpensive CO2 capture and storage [3]. More generally, engineered reaction-driven cracking could supplement or replace hydraulic fracture in geothermal systems, solution mining, and extraction of tight oil and gas. The controls on reaction-driven cracking are poorly understood. Hydration and carbonation reactions can be self-limiting, since they potentially reduce permeability and armor reactive surfaces [4]. Also, in some cases, hydration or carbonation may take place at constant volume. Small changes in volume due to precipitation of solid products increases stress, destabilizing solid reactants, until precipitation and dissolution rates become equal at a steady state stress [5]. In a third case, volume change due to precipitation of solid products causes brittle failure. This has been invoked on qualitative grounds to explain, e.g., complete serpentinization of mantle peridotite [6]. Below ~ 300°C, the available potential energy for hydration and carbonation of olivine could produce stresses of 100's of MPa [2], sufficient to fracture rocks to 10 km depth or more, causing brittle failure below the steady state stress required

  15. Asynchronous Event-Driven Particle Algorithms

    SciTech Connect

    Donev, A

    2007-02-28

    We present in a unifying way the main components of three examples of asynchronous event-driven algorithms for simulating physical systems of interacting particles. The first example, hard-particle molecular dynamics (MD), is well-known. We also present a recently-developed diffusion kinetic Monte Carlo (DKMC) algorithm, as well as a novel event-driven algorithm for Direct Simulation Monte Carlo (DSMC). Finally, we describe how to combine MD with DSMC in an event-driven framework, and discuss some promises and challenges for event-driven simulation of realistic physical systems.

  16. Asynchronous Event-Driven Particle Algorithms

    SciTech Connect

    Donev, A

    2007-08-30

    We present, in a unifying way, the main components of three asynchronous event-driven algorithms for simulating physical systems of interacting particles. The first example, hard-particle molecular dynamics (MD), is well-known. We also present a recently-developed diffusion kinetic Monte Carlo (DKMC) algorithm, as well as a novel stochastic molecular-dynamics algorithm that builds on the Direct Simulation Monte Carlo (DSMC). We explain how to effectively combine event-driven and classical time-driven handling, and discuss some promises and challenges for event-driven simulation of realistic physical systems.

  17. Photogated humidity-driven motility

    NASA Astrophysics Data System (ADS)

    Zhang, Lidong; Liang, Haoran; Jacob, Jolly; Naumov, Panče

    2015-06-01

    Hygroinduced motion is a fundamental process of energy conversion that is essential for applications that require contactless actuation in response to the day-night rhythm of atmospheric humidity. Here we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapour by a flexible dynamic element that harnesses the chemical potential across very small humidity gradients for perpetual motion can be effectively modulated with light. A mechanically robust material capable of rapid exchange of water with the surroundings is prepared that undergoes swift locomotion in effect to periodic shape reconfiguration with turnover frequency of <150 min-1. The element can lift objects ~85 times heavier and can transport cargos ~20 times heavier than itself. Having an azobenzene-containing conjugate as a photoactive dopant, this entirely humidity-driven self-actuation can be controlled remotely with ultraviolet light, thus setting a platform for next-generation smart biomimetic hybrids.

  18. Light-driven phase shifter

    DOEpatents

    Early, James W.

    1990-01-01

    A light-driven phase shifter is provided for modulating a transmission light beam. A gaseous medium such as argon is provided with electron energy states excited to populate a metastable state. A tunable dye laser is selected with a wavelength effective to deplete the metastable electron state and may be intensity modulated. The dye laser is directed through the gaseous medium to define a first optical path having an index of refraction determined by the gaseous medium having a depleted metastable electron state. A transmission laser beam is also directed through the gaseous medium to define a second optical path at least partially coincident with the first optical path. The intensity of the dye laser beam may then be varied to phase modulate the transmission laser beam.

  19. Acoustically driven arrayed waveguide grating.

    PubMed

    Crespo-Poveda, A; Hernández-Mínguez, A; Gargallo, B; Biermann, K; Tahraoui, A; Santos, P V; Muñoz, P; Cantarero, A; de Lima, M M

    2015-08-10

    We demonstrate compact tunable phased-array wavelength-division multiplexers driven by surface acoustic waves (SAWs) in the low GHz range. The devices comprise two couplers, which respectively split and combine the optical signal, linked by an array of single-mode waveguides (WGs). Two different layouts are presented, in which multi-mode interference couplers or free propagating regions were separately employed as couplers. The multiplexers operate on five equally distributed wavelength channels, with a spectral separation of 2 nm. A standing SAW modulates the refractive index of the arrayed WGs. Each wavelength component periodically switches paths between the output channel previously asigned by the design and the adjacent channels, at a fixed applied acoustic power. The devices were monolithically fabricated on (Al,Ga)As. A good agreement between theory and experiment is achieved.

  20. Laser-driven fusion reactor

    DOEpatents

    Hedstrom, J.C.

    1973-10-01

    A laser-driven fusion reactor consisting of concentric spherical vessels in which the thermonuclear energy is derived from a deuterium-tritium (D + T) burn within a pellet'', located at the center of the vessels and initiated by a laser pulse. The resulting alpha -particle energy and a small fraction of the neutron energy are deposited within the pellet; this pellet energy is eventually transformed into sensible heat of lithium in a condenser outside the vessels. The remaining neutron energy is dissipated in a lithium blanket, located within the concentric vessels, where the fuel ingredient, tritium, is also produced. The heat content of the blanket and of the condenser lithium is eventually transferred to a conventional thermodynamic plant where the thermal energy is converted to electrical energy in a steam Rankine cycle. (Official Gazette)

  1. Multifunctionalities driven by ferroic domains

    SciTech Connect

    Yang, J. C.; Huang, Y. L.; Chu, Y. H.; He, Q.

    2014-08-14

    Considerable attention has been paid to ferroic systems in pursuit of advanced applications in past decades. Most recently, the emergence and development of multiferroics, which exhibit the coexistence of different ferroic natures, has offered a new route to create functionalities in the system. In this manuscript, we step from domain engineering to explore a roadmap for discovering intriguing phenomena and multifunctionalities driven by periodic domain patters. As-grown periodic domains, offering exotic order parameters, periodic local perturbations and the capability of tailoring local spin, charge, orbital and lattice degrees of freedom, are introduced as modeling templates for fundamental studies and novel applications. We discuss related significant findings on ferroic domain, nanoscopic domain walls, and conjunct heterostructures based on the well-organized domain patterns, and end with future prospects and challenges in the field.

  2. Current-driven atomic waterwheels.

    PubMed

    Dundas, Daniel; McEniry, Eunan J; Todorov, Tchavdar N

    2009-02-01

    A current induces forces on atoms inside the conductor that carries it. It is now possible to compute these forces from scratch, and to perform dynamical simulations of the atomic motion under current. One reason for this interest is that current can be a destructive force--it can cause atoms to migrate, resulting in damage and in the eventual failure of the conductor. But one can also ask, can current be made to do useful work on atoms? In particular, can an atomic-scale motor be driven by electrical current, as it can be by other mechanisms? For this to be possible, the current-induced forces on a suitable rotor must be non-conservative, so that net work can be done per revolution. Here we show that current-induced forces in atomic wires are not conservative and that they can be used, in principle, to drive an atomic-scale waterwheel. PMID:19197311

  3. Impulse-driven Micromechanism Capsule

    NASA Astrophysics Data System (ADS)

    Ito, Takahiro; Ishimori, Shohei; Hayashi, Teru

    We have developed a traveling small capsule, which has a smooth outer surface and is driven by inertia force and friction force. Measuring only 7 mm in diameter and 12 mm in length, it is sufficiently small to be placed in the human gullet or intestines. The capsule contains a small magnet and a coil, and an electric pulse drives the magnet to move the capsule. We performed an experimental investigation on making our capsule travel on a plastic material, which has similar elasticity characteristics to the living body. We also showed that it can travel on the surface of a pig's intestine. Our capsule may be useful for medical treatments such as inspection, drug delivery and operation.

  4. Photogated humidity-driven motility

    PubMed Central

    Zhang, Lidong; Liang, Haoran; Jacob, Jolly; Naumov, Panče

    2015-01-01

    Hygroinduced motion is a fundamental process of energy conversion that is essential for applications that require contactless actuation in response to the day–night rhythm of atmospheric humidity. Here we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapour by a flexible dynamic element that harnesses the chemical potential across very small humidity gradients for perpetual motion can be effectively modulated with light. A mechanically robust material capable of rapid exchange of water with the surroundings is prepared that undergoes swift locomotion in effect to periodic shape reconfiguration with turnover frequency of <150 min−1. The element can lift objects ∼85 times heavier and can transport cargos ∼20 times heavier than itself. Having an azobenzene-containing conjugate as a photoactive dopant, this entirely humidity-driven self-actuation can be controlled remotely with ultraviolet light, thus setting a platform for next-generation smart biomimetic hybrids. PMID:26067649

  5. Photogated humidity-driven motility.

    PubMed

    Zhang, Lidong; Liang, Haoran; Jacob, Jolly; Naumov, Panče

    2015-06-11

    Hygroinduced motion is a fundamental process of energy conversion that is essential for applications that require contactless actuation in response to the day-night rhythm of atmospheric humidity. Here we demonstrate that mechanical bistability caused by rapid and anisotropic adsorption and desorption of water vapour by a flexible dynamic element that harnesses the chemical potential across very small humidity gradients for perpetual motion can be effectively modulated with light. A mechanically robust material capable of rapid exchange of water with the surroundings is prepared that undergoes swift locomotion in effect to periodic shape reconfiguration with turnover frequency of <150 min(-1). The element can lift objects ∼85 times heavier and can transport cargos ∼20 times heavier than itself. Having an azobenzene-containing conjugate as a photoactive dopant, this entirely humidity-driven self-actuation can be controlled remotely with ultraviolet light, thus setting a platform for next-generation smart biomimetic hybrids.

  6. Remarks on Tachyon Driven Cosmology

    NASA Astrophysics Data System (ADS)

    Sen, Ashoke

    2005-08-01

    We begin by reviewing the results on the decay of unstable D-branes in type II string theory, and the open-closed string duality proposal that arises from these studies. We then apply this proposal to the study of tachyon driven cosmology, namely cosmological solutions describing the decay of unstable space filling D-branes. This naturally gives rise to a time reversal invariant bounce solution with positive spatial curvature. In the absence of a bulk cosmological constant the universe always begins with a big bang and ends in a big crunch. In the presence of a bulk cosmological constant one may get non-singular cosmological solutions for some special range of initial conditions on the tachyon.

  7. Indirectly driven targets for ignition

    SciTech Connect

    Wilson, D.C.; Krauser, W.J.

    1994-12-31

    Both Los Alamos and Lawrence Livermore Laboratories have studied capsule and laser driven target designs for the National Ignition Facility. The current hohlraum design is a 2.76mm radius, 9.5mm long gold cylinder with 1.39mm radius laser entrance holes covered by 1{mu}m thick plastic foils. Laser beams strike the inside cylinder wall from two separate cones with a peak power less than 400 TW. The problem with a pressure pulse caused by wall plasma stagnating on axis has been overcome by filling the hohlraum with gas. Currently this is equi-molar hydrogen-helium gas at 0.83 mg/cc density. One capsule uses a 160 {mu}m plastic ablator doped with oxygen and bromine surrounding an 80 {mu}m thick DT ice layer with an inner radius of 0.87 mm. Los Alamos integrated calculations of the hohlraum and this capsule using 1.4 MJ of laser energy achieve yields of 4.9 MJ using LTE atomic physics, and 3.5 MJ with non-LTE. This confirms Livermore calculations of ignition. For radiation driven implosions, a beryllium ablator offers a viable alternative to plastic. It is strong enough to contain high DT pressures. Copper, soluble at required levels, is an excellent dopant to add opacity. A beryllium capsule with a 155 {mu}m thick ablator doped with 0.9 atom % copper, and the same inner dimensions as the plastic capsule, placed in a similar hohlraum , yields 6.9 MJ with LTE. Although these calculations show the designs are sensitive, they add to the confidence that NIF can achieve ignition. Using their best integrated calculations which are not yet fully optimized, they confirm Livermore calculations of ignition with a plastic capsule, and have added an alternate capsule design with a beryllium ablator.

  8. Gravity-Driven Hydraulic Fractures

    NASA Astrophysics Data System (ADS)

    Germanovich, L. N.; Garagash, D.; Murdoch, L. C.; Robinowitz, M.

    2014-12-01

    This study is motived by a new method for disposing of nuclear waste by injecting it as a dense slurry into a hydraulic fracture that grows downward to great enough depth to permanently isolate the waste. Disposing of nuclear waste using gravity-driven hydraulic fractures is mechanically similar to the upward growth of dikes filled with low density magma. A fundamental question in both applications is how the injected fluid controls the propagation dynamics and fracture geometry (depth and breadth) in three dimensions. Analog experiments in gelatin [e.g., Heimpel and Olson, 1994; Taisne and Tait, 2009] show that fracture breadth (the short horizontal dimension) remains nearly stationary when the process in the fracture "head" (where breadth is controlled) is dominated by solid toughness, whereas viscous fluid dissipation is dominant in the fracture tail. We model propagation of the resulting gravity-driven (buoyant or sinking), finger-like fracture of stationary breadth with slowly varying opening along the crack length. The elastic response to fluid loading in a horizontal cross-section is local and can be treated similar to the classical Perkins-Kern-Nordgren (PKN) model of hydraulic fracturing. The propagation condition for a finger-like crack is based on balancing the global energy release rate due to a unit crack extension with the rock fracture toughness. It allows us to relate the net fluid pressure at the tip to the fracture breadth and rock toughness. Unlike the PKN fracture, where breadth is known a priori, the final breadth of a finger-like fracture is a result of processes in the fracture head. Because the head is much more open than the tail, viscous pressure drop in the head can be neglected leading to a 3D analog of Weertman's hydrostatic pulse. This requires relaxing the local elasticity assumption of the PKN model in the fracture head. As a result, we resolve the breadth, and then match the viscosity-dominated tail with the 3-D, toughness

  9. Evaluation of Respondent-Driven Sampling

    PubMed Central

    McCreesh, Nicky; Frost, Simon; Seeley, Janet; Katongole, Joseph; Tarsh, Matilda Ndagire; Ndunguse, Richard; Jichi, Fatima; Lunel, Natasha L; Maher, Dermot; Johnston, Lisa G; Sonnenberg, Pam; Copas, Andrew J; Hayes, Richard J; White, Richard G

    2012-01-01

    Background Respondent-driven sampling is a novel variant of link-tracing sampling for estimating the characteristics of hard-to-reach groups, such as HIV prevalence in sex-workers. Despite its use by leading health organizations, the performance of this method in realistic situations is still largely unknown. We evaluated respondent-driven sampling by comparing estimates from a respondent-driven sampling survey with total-population data. Methods Total-population data on age, tribe, religion, socioeconomic status, sexual activity and HIV status were available on a population of 2402 male household-heads from an open cohort in rural Uganda. A respondent-driven sampling (RDS) survey was carried out in this population, employing current methods of sampling (RDS sample) and statistical inference (RDS estimates). Analyses were carried out for the full RDS sample and then repeated for the first 250 recruits (small sample). Results We recruited 927 household-heads. Full and small RDS samples were largely representative of the total population, but both samples under-represented men who were younger, of higher socioeconomic status, and with unknown sexual activity and HIV status. Respondent-driven-sampling statistical-inference methods failed to reduce these biases. Only 31%-37% (depending on method and sample size) of RDS estimates were closer to the true population proportions than the RDS sample proportions. Only 50%-74% of respondent-driven-sampling bootstrap 95% confidence intervals included the population proportion. Conclusions Respondent-driven sampling produced a generally representative sample of this well-connected non-hidden population. However, current respondent-driven-sampling inference methods failed to reduce bias when it occurred. Whether the data required to remove bias and measure precision can be collected in a respondent-driven sampling survey is unresolved. Respondent-driven sampling should be regarded as a (potentially superior) form of convenience

  10. Bubble-driven inertial micropump

    NASA Astrophysics Data System (ADS)

    Torniainen, Erik D.; Govyadinov, Alexander N.; Markel, David P.; Kornilovitch, Pavel E.

    2012-12-01

    The fundamental action of the bubble-driven inertial micropump is investigated. The pump has no moving parts and consists of a thermal resistor placed asymmetrically within a straight channel connecting two reservoirs. Using numerical simulations, the net flow is studied as a function of channel geometry, resistor location, vapor bubble strength, fluid viscosity, and surface tension. Two major regimes of behavior are identified: axial and non-axial. In the axial regime, the drive bubble either remains inside the channel, or continues to grow axially when it reaches the reservoir. In the non-axial regime, the bubble grows out of the channel and in all three dimensions while inside the reservoir. The net flow in the axial regime is parabolic with respect to the hydraulic diameter of the channel cross-section, but in the non-axial regime it is not. From numerical modeling, it is determined that the net flow is maximal when the axial regime crosses over to the non-axial regime. To elucidate the basic physical principles of the pump, a phenomenological one-dimensional model is developed and solved. A linear array of micropumps has been built using silicon-SU8 fabrication technology that is used to manufacture thermal inkjet printheads. Semi-continuous pumping across a 2 mm-wide channel has been demonstrated experimentally. Measured net flow with respect to viscosity variation is in excellent agreement with simulation results.

  11. Cosmic ray driven Galactic winds

    NASA Astrophysics Data System (ADS)

    Recchia, S.; Blasi, P.; Morlino, G.

    2016-11-01

    The escape of cosmic rays from the Galaxy leads to a gradient in the cosmic ray pressure that acts as a force on the background plasma, in the direction opposite to the gravitational pull. If this force is large enough to win against gravity, a wind can be launched that removes gas from the Galaxy, thereby regulating several physical processes, including star formation. The dynamics of these cosmic ray driven winds is intrinsically non-linear in that the spectrum of cosmic rays determines the characteristics of the wind (velocity, pressure, magnetic field) and in turn the wind dynamics affects the cosmic ray spectrum. Moreover, the gradient of the cosmic ray distribution function causes excitation of Alfvén waves, that in turn determines the scattering properties of cosmic rays, namely their diffusive transport. These effects all feed into each other so that what we see at the Earth is the result of these non-linear effects. Here, we investigate the launch and evolution of such winds, and we determine the implications for the spectrum of cosmic rays by solving together the hydrodynamical equations for the wind and the transport equation for cosmic rays under the action of self-generated diffusion and advection with the wind and the self-excited Alfvén waves.

  12. Cosmic ray driven Galactic winds

    NASA Astrophysics Data System (ADS)

    Recchia, S.; Blasi, P.; Morlino, G.

    2016-08-01

    The escape of cosmic rays from the Galaxy leads to a gradient in the cosmic ray pressure that acts as a force on the background plasma, in the direction opposite to the gravitational pull. If this force is large enough to win against gravity, a wind can be launched that removes gas from the Galaxy, thereby regulating several physical processes, including star formation. The dynamics of these cosmic ray driven winds is intrinsically non-linear in that the spectrum of cosmic rays determines the characteristics of the wind (velocity, pressure, magnetic field) and in turn the wind dynamics affects the cosmic ray spectrum. Moreover, the gradient of the cosmic ray distribution function causes excitation of Alfvén waves, that in turn determine the scattering properties of cosmic rays, namely their diffusive transport. These effects all feed into each other so that what we see at the Earth is the result of these non-linear effects. Here we investigate the launch and evolution of such winds, and we determine the implications for the spectrum of cosmic rays by solving together the hydrodynamical equations for the wind and the transport equation for cosmic rays under the action of self-generated diffusion and advection with the wind and the self-excited Alfvén waves.

  13. Capillary-driven automatic packaging.

    PubMed

    Ding, Yuzhe; Hong, Lingfei; Nie, Baoqing; Lam, Kit S; Pan, Tingrui

    2011-04-21

    Packaging continues to be one of the most challenging steps in micro-nanofabrication, as many emerging techniques (e.g., soft lithography) are incompatible with the standard high-precision alignment and bonding equipment. In this paper, we present a simple-to-operate, easy-to-adapt packaging strategy, referred to as Capillary-driven Automatic Packaging (CAP), to achieve automatic packaging process, including the desired features of spontaneous alignment and bonding, wide applicability to various materials, potential scalability, and direct incorporation in the layout. Specifically, self-alignment and self-engagement of the CAP process induced by the interfacial capillary interactions between a liquid capillary bridge and the top and bottom substrates have been experimentally characterized and theoretically analyzed with scalable implications. High-precision alignment (of less than 10 µm) and outstanding bonding performance (up to 300 kPa) has been reliably obtained. In addition, a 3D microfluidic network, aligned and bonded by the CAP technique, has been devised to demonstrate the applicability of this facile yet robust packaging technique for emerging microfluidic and bioengineering applications.

  14. Adaptation Driven by Spatial Heterogeneities

    NASA Astrophysics Data System (ADS)

    Hermsen, Rutger

    2011-03-01

    Biological evolution and ecology are intimately linked, because the reproductive success or ``fitness'' of an organism depends crucially on its ecosystem. Yet, most models of evolution (or population genetics) consider homogeneous, fixed-size populations subjected to a constant selection pressure. To move one step beyond such ``mean field'' descriptions, we discuss stochastic models of evolution driven by spatial heterogeneity. We imagine a population whose range is limited by a spatially varying environmental parameter, such as a temperature or the concentration of an antibiotic drug. Individuals in the population replicate, die and migrate stochastically. Also, by mutation, they can adapt to the environmental stress and expand their range. This way, adaptation and niche expansion go hand in hand. This mode of evolution is qualitatively different from the usual notion of a population climbing a fitness gradient. We analytically calculate the rate of adaptation by solving a first passage time problem. Interestingly, the joint effects of reproduction, death, mutation and migration result in two distinct parameter regimes depending on the relative time scales of mutation and migration. We argue that the proposed scenario may be relevant for the rapid evolution of antibiotic resistance. This work was supported by the Center for Theoretical Biological Physics sponsored by the National Science Foundation (NSF) (Grant PHY-0822283).

  15. Laboratory blast wave driven instabilities

    NASA Astrophysics Data System (ADS)

    Kuranz, Carolyn

    2008-11-01

    This presentation discusses experiments involving the evolution of hydrodynamic instabilities in the laboratory under high-energy-density (HED) conditions. These instabilities are driven by blast waves, which occur following a sudden, finite release of energy, and consist of a shock front followed by a rarefaction wave. When a blast wave crosses an interface with a decrease in density, hydrodynamic instabilities will develop. Instabilities evolving under HED conditions are relevant to astrophysics. These experiments include target materials scaled in density to the He/H layer in SN1987A. About 5 kJ of laser energy from the Omega Laser facility irradiates a 150 μm plastic layer that is followed by a low-density foam layer. A blast wave structure similar to those in supernovae is created in the plastic layer. The blast wave crosses an interface having a 2D or 3D sinusoidal structure that serves as a seed perturbation for hydrodynamic instabilities. This produces unstable growth dominated by the Rayleigh-Taylor (RT) instability in the nonlinear regime. We have detected the interface structure under these conditions using x-ray backlighting. Recent advances in our diagnostic techniques have greatly improved the resolution of our x-ray radiographic images. Under certain conditions, the improved images show some mass extending beyond the RT spike and penetrating further than previously observed or predicted by current simulations. The observed effect is potentially of great importance as a source of mass transport to places not anticipated by current theory and simulation. I will discuss the amount of mass in these spike extensions, the associated uncertainties, and hypotheses regarding their origin We also plan to show comparisons of experiments using single mode and multimode as well as 2D and 3D initial conditions. This work is sponsored by DOE/NNSA Research Grants DE-FG52-07NA28058 (Stewardship Sciences Academic Alliances) and DE-FG52-04NA00064 (National Laser User

  16. Wind-driven propellers (or "windmills")

    NASA Technical Reports Server (NTRS)

    Munk, Max M

    1923-01-01

    Wind-driven propellers are much used as sources of power for equipment such as radios. This report establishes the principles involved and acquaints the reader with rules for design of such windmills.

  17. Gas-driven filter pressing in magmas

    USGS Publications Warehouse

    Sisson, T.W.; Bacon, C.R.

    1999-01-01

    Most silicic and some mafic magmas expand via second boiling if they crystallize at depths of about 10 km or less. The buildup of gas pressure due to second boiling can be relieved by expulsion of melt out of the region of crystallization, and this process of gas-driven filter pressing assists the crystallization differentiation of magmas. For gas-driven filter pressing to be effective, the region of crystallization must inflate slowly relative to buildup of pressure and expulsion of melt These conditions are satisfied in undercooled magmatic inclusions and in thin sheets of primitive magma underplating cooler magma reservoirs. Gas-driven filter pressing thereby adds fractionated melt to magma bodies. Gas-driven filter pressing is probably the dominant process by which highly evolved melts segregate from crystal mush to form aplitic dikes in granitic plutons; this process could also account for the production of voluminous, crystal-poor rhyolites.

  18. Sensitivity to Increased Task Demands: Contributions from Data-Driven and Conceptually Driven Information Processing Deficits.

    ERIC Educational Resources Information Center

    Gillam, Ronald B.; Hoffman, LaVae M.; Marler, Jeffrey A.; Wynn-Dancy, M. Lorraine

    2002-01-01

    This article explores evidence related to the idea that children with language impairments present co-occurring limitations in data-driven and conceptually driven processing. It concludes that together, these limitations contribute to a heightened sensitivity to increasing task demands in children with language impairments. Assessment and…

  19. Multiple displacement motor driven power drive unit

    SciTech Connect

    Burandt, W. A.

    1985-12-03

    A multiple displacement motor driven power drive unit having two separate hydraulic systems each with a variable displacement hydraulic motor having its output connected to a torque summing gear train. A control provides for operation of one or the other of the motors at full displacement while the other motor is at zero displacement and free-wheels. There is a manual mechanical control operation with both motors simultaneously set at one-half of full displacement and driving the torque summing gear train. The change in motor displacements to one-half full displacement accomplishes velocity summing within the hydraulics. The multiple displacement motor driven power drive unit accomplishes the power efficiency of a multiple motor driven power drive unit utilizing a speed summing gear train with fixed displacement motors, but without the complexities associated with the use of a speed summing gear train and brakes.

  20. Microphysics of Cosmic Ray Driven Plasma Instabilities

    NASA Astrophysics Data System (ADS)

    Bykov, A. M.; Brandenburg, A.; Malkov, M. A.; Osipov, S. M.

    2013-10-01

    Energetic nonthermal particles (cosmic rays, CRs) are accelerated in supernova remnants, relativistic jets and other astrophysical objects. The CR energy density is typically comparable with that of the thermal components and magnetic fields. In this review we discuss mechanisms of magnetic field amplification due to instabilities induced by CRs. We derive CR kinetic and magnetohydrodynamic equations that govern cosmic plasma systems comprising the thermal background plasma, comic rays and fluctuating magnetic fields to study CR-driven instabilities. Both resonant and non-resonant instabilities are reviewed, including the Bell short-wavelength instability, and the firehose instability. Special attention is paid to the longwavelength instabilities driven by the CR current and pressure gradient. The helicity production by the CR current-driven instabilities is discussed in connection with the dynamo mechanisms of cosmic magnetic field amplification.

  1. Microphysics of Cosmic Ray Driven Plasma Instabilities

    NASA Astrophysics Data System (ADS)

    Bykov, A. M.; Brandenburg, A.; Malkov, M. A.; Osipov, S. M.

    Energetic nonthermal particles (cosmic rays, CRs) are accelerated in supernova remnants, relativistic jets and other astrophysical objects. The CR energy density is typically comparable with that of the thermal components and magnetic fields. In this review we discuss mechanisms of magnetic field amplification due to instabilities induced by CRs. We derive CR kinetic and magnetohydrodynamic equations that govern cosmic plasma systems comprising the thermal background plasma, comic rays and fluctuating magnetic fields to study CR-driven instabilities. Both resonant and non-resonant instabilities are reviewed, including the Bell short-wavelength instability, and the firehose instability. Special attention is paid to the longwavelength instabilities driven by the CR current and pressure gradient. The helicity production by the CR current-driven instabilities is discussed in connection with the dynamo mechanisms of cosmic magnetic field amplification.

  2. Metamodel-Driven Evolution with Grammar Inference

    NASA Astrophysics Data System (ADS)

    Bryant, Barrett R.; Liu, Qichao; Mernik, Marjan

    2010-10-01

    Domain-specific modeling (DSM) has become one of the most popular techniques for incorporating model-driven engineering (MDE) into software engineering. In DSM, domain experts define metamodels to describe the essential problems in a domain. A model conforms to a schema definition represented by a metamodel in a similar manner to a programming language conforms to a grammar. Metamodel-driven evolution is when a metamodel undergoes evolutions to incorporate new concerns in the domain. However, this results in losing the ability to use existing model instances. Grammar inference is the problem of inferring a grammar from sample strings which the grammar should generate. This paper describes our work in solving the problem of metamodel-driven evolution with grammar inference, by inferring the metamodel from model instances.

  3. Light-Driven Polymeric Bimorph Actuators

    NASA Technical Reports Server (NTRS)

    Adamovsky, Gregory; Sarkisov, Sergey S.; Curley, Michael J.

    2009-01-01

    Light-driven polymeric bimorph actuators are being developed as alternatives to prior electrically and optically driven actuators in advanced, highly miniaturized devices and systems exemplified by microelectromechanical systems (MEMS), micro-electro-optical-mechanical systems (MEOMS), and sensor and actuator arrays in smart structures. These light-driven polymeric bimorph actuators are intended to satisfy a need for actuators that (1) in comparison with the prior actuators, are simpler and less power-hungry; (2) can be driven by low-power visible or mid-infrared light delivered through conventional optic fibers; and (3) are suitable for integration with optical sensors and multiple actuators of the same or different type. The immediate predecessors of the present light-driven polymeric bimorph actuators are bimorph actuators that exploit a photorestrictive effect in lead lanthanum zirconate titanate (PLZT) ceramics. The disadvantages of the PLZT-based actuators are that (1) it is difficult to shape the PLZT ceramics, which are hard and brittle; (2) for actuation, it is necessary to use ultraviolet light (wavelengths < 380 nm), which must be generated by use of high-power, high-pressure arc lamps or lasers; (3) it is difficult to deliver sufficient ultraviolet light through conventional optical fibers because of significant losses in the fibers; (4) the response times of the PLZT actuators are of the order of several seconds unacceptably long for typical applications; and (5) the maximum mechanical displacements of the PLZT-based actuators are limited to those characterized by low strains beyond which PLZT ceramics disintegrate because of their brittleness. The basic element of a light-driven bimorph actuator of the present developmental type is a cantilever beam comprising two layers, at least one of which is a polymer that exhibits a photomechanical effect (see figure). The dominant mechanism of the photomechanical effect is a photothermal one: absorption of

  4. New Instabilities in Line Driven Winds

    NASA Technical Reports Server (NTRS)

    Martens, P. C. H.

    1985-01-01

    The physical mechanisms which potentially lead to instabilities in line driven winds, the drift instability and the line shape instability, are discussed. A general three dimensional treatment of the stability problem of line driven winds which leads to the general dispersion equation is proposed. From this dispersion equation automatically a third physical mechanism driving instability in stellar winds is deduced; the thermal drift instability which is related to changes in absorption of radiation caused by temperature perturbations. This mechanism results in growing inwardly propagating sound waves.

  5. Polynomial driven time base and PN generator

    NASA Technical Reports Server (NTRS)

    Brokl, S. S.

    1983-01-01

    In support of the planetary radar upgrade new hardware was designed to increase resolution and take advantage of new technology. Included is a description of the Polynomial Driven Time Base and PN Generator which is used for range gate coding in the planetary radar system.

  6. High-explosive driven crowbar switch

    DOEpatents

    Dike, Robert S.; Kewish, Jr., Ralph W.

    1976-01-13

    The disclosure relates to a compact explosive driven switch for use as a low resistance, low inductance crowbar switch. A high-explosive charge extrudes a deformable conductive metallic plate through a polyethylene insulating layer to achieve a hard current contact with a supportive annular conductor.

  7. Microwave-driven ultraviolet light sources

    DOEpatents

    Manos, Dennis M.; Diggs, Jessie; Ametepe, Joseph D.

    2002-01-29

    A microwave-driven ultraviolet (UV) light source is provided. The light source comprises an over-moded microwave cavity having at least one discharge bulb disposed within the microwave cavity. At least one magnetron probe is coupled directly to the microwave cavity.

  8. Mission Driven and Data Informed Leadership

    ERIC Educational Resources Information Center

    Holter, Anthony C.; Frabutt, James M.

    2012-01-01

    The contemporary challenges facing Catholic schools and Catholic school leaders are widely known. Effective and systemic solutions to these mounting challenges are less widely known or discussed. This article highlights the skills, knowledge, and dispositions associated with mission driven and data informed leadership--an orientation to school…

  9. Terahertz-driven linear electron acceleration

    SciTech Connect

    Nanni, Emilio A.; Huang, Wenqian R.; Hong, Kyung-Han; Ravi, Koustuban; Fallahi, Arya; Moriena, Gustavo; Dwayne Miller, R. J.; Kärtner, Franz X.

    2015-10-06

    The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30–50 MeVm-1 gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/proton accelerators with simple accelerating structures, high repetition rates and significant charge per bunch. As a result, these ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams.

  10. Mouse Driven Window Graphics for Network Teaching.

    ERIC Educational Resources Information Center

    Makinson, G. J.; And Others

    Computer enhanced teaching of computational mathematics on a network system driving graphics terminals is being redeveloped for a mouse-driven, high resolution, windowed environment of a UNIX work station. Preservation of the features of networked access by heterogeneous terminals is provided by the use of the X Window environment. A dmonstrator…

  11. Work in the Knowledge-Driven Economy.

    ERIC Educational Resources Information Center

    Bayliss, Valerie

    2001-01-01

    The knowledge-driven economy has become a "given," yet there is disagreement over what it entails and who is helped or harmed. The aging of the work force, disappearance of unskilled jobs, and changes in business and social organization suggest that the social, economic, and infrastructural problems of the knowledge economy will not solve…

  12. Osmosis is not driven by water dilution.

    PubMed

    Kramer, Eric M; Myers, David R

    2013-04-01

    There is a misconception among plant scientists that osmosis is driven by the tendency of solutes to dilute water. In this opinion article, we discuss the quantitative and qualitative failures of this view, and go on to review the correct kinetic picture of osmosis as it appears in physics textbooks.

  13. Terahertz-driven linear electron acceleration

    PubMed Central

    Nanni, Emilio A.; Huang, Wenqian R.; Hong, Kyung-Han; Ravi, Koustuban; Fallahi, Arya; Moriena, Gustavo; Dwayne Miller, R. J.; Kärtner, Franz X.

    2015-01-01

    The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30–50 MeV m−1 gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/proton accelerators with simple accelerating structures, high repetition rates and significant charge per bunch. These ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams. PMID:26439410

  14. Terahertz-driven linear electron acceleration

    DOE PAGES

    Nanni, Emilio A.; Huang, Wenqian R.; Hong, Kyung-Han; Ravi, Koustuban; Fallahi, Arya; Moriena, Gustavo; Dwayne Miller, R. J.; Kärtner, Franz X.

    2015-10-06

    The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30–50 MeVm-1 gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/proton acceleratorsmore » with simple accelerating structures, high repetition rates and significant charge per bunch. As a result, these ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams.« less

  15. ISKME Special Series Part I: Data Driven

    ERIC Educational Resources Information Center

    Panettieri, Joseph C.

    2006-01-01

    In early December 2005, the School District of Philadelphia announced that, for the fourth consecutive year, students showed measurable improvement on standardized, nationally normed TerraNova tests. The school's good performance was induced by a well managed instructional program that includes data-driven instruction and decision-making…

  16. Making Data-Driven Decisions: Silent Reading

    ERIC Educational Resources Information Center

    Trudel, Heidi

    2007-01-01

    Due in part to conflicting opinions and research results, the practice of sustained silent reading (SSR) in schools has been questioned. After a frustrating experience with SSR, the author of this article began a data-driven decision-making process to gain new insights on how to structure silent reading in a classroom, including a comparison…

  17. Light modulated electron beam driven radiofrequency emitter

    DOEpatents

    Wilson, M.T.; Tallerico, P.J.

    1979-10-10

    The disclosure relates to a light modulated electron beam-driven radiofrequency emitter. Pulses of light impinge on a photoemissive device which generates an electron beam having the pulse characteristics of the light. The electron beam is accelerated through a radiofrequency resonator which produces radiofrequency emission in accordance with the electron, hence, the light pulses.

  18. What Data for Data-Driven Learning?

    ERIC Educational Resources Information Center

    Boulton, Alex

    2012-01-01

    Corpora have multiple affordances, not least for use by teachers and learners of a foreign language (L2) in what has come to be known as "data-driven learning" or DDL. The corpus and concordance interface were originally conceived by and for linguists, so other users need to adopt the role of "language researcher" to make the most of them. Despite…

  19. Persistence of Value-Driven Attentional Capture

    ERIC Educational Resources Information Center

    Anderson, Brian A.; Yantis, Steven

    2013-01-01

    Stimuli that have previously been associated with the delivery of reward involuntarily capture attention when presented as unrewarded and task-irrelevant distractors in a subsequent visual search task. It is unknown how long such effects of reward learning on attention persist. One possibility is that value-driven attentional biases are plastic…

  20. Poleward migration of eddy driven jets

    NASA Astrophysics Data System (ADS)

    Chemke, Rei; Kaspi, Yohai

    2014-05-01

    There are observational evidence for a poleward migration of temporal anomalies of zonal winds in the upper troposphere. We show that such poleward migration can be due to poleward migration of eddy-driven jets; In fact, any eddy driven baroclinic jet should propagate poleward over time due to the variation of baroclinicity across the jet due to the sphericity of the planet. We demonstrate this using a high resolution idealized GCM where we examine the eddy driven jets over a wide range of rotation rates (up to 24 times the rotation rate of Earth). Unlike Earth-like rotation rates, where the eddy driven jet and the subtropical jet usually merge, at higher rotation rates the eddy driven jets are clearly separated from the subtropical jet and migrate poleward, while the subtropical jets remain in a constant latitude over time. The poleward drift is caused because measures of baroclinicity, such as Eady growth rate and supercriticality have a poleward bias due to the variation of the Coriolis parameter across the jet. This results in a poleward biased eddy momentum flux convergence relative to the mean jet, which overtime deflects the jet poleward. This is demonstrated systematically over the series of numerical simulations we present. As the rotation rate increases, and more (narrower) jets emerge the migration rate becomes smaller due to less eddy momentum flux convergence over the narrower baroclinic zones. This mechanism is consistent with eddy life cycle studies, which show the effects of sphericity on eddy propagation. In addition, we suggest scaling for the meridional scale of the jets and their spacing as function of the planetary rotation rate and latitude.

  1. Coherent states of the driven Rydberg atom: Quantum-classical correspondence of periodically driven systems

    SciTech Connect

    Vela-Arevalo, Luz V.; Fox, Ronald F.

    2005-06-15

    A methodology to calculate generalized coherent states for a periodically driven system is presented. We study wave packets constructed as a linear combination of suitable Floquet states of the three-dimensional Rydberg atom in a microwave field. The driven coherent states show classical space localization, spreading, and revivals and remain localized along the classical trajectory. The microwave strength and frequency have a great effect in the localization of Floquet states, since quasienergy avoided crossings produce delocalization of the Floquet states, showing that tuning of the parameters is very important. Using wavelet-based time-frequency analysis, the classical phase-space structure is determined, which allows us to show that the driven coherent state is located in a large regular region in which the z coordinate is in resonance with the external field. The expectation values of the wave packet show that the driven coherent state evolves along the classical trajectory.

  2. Using Two Different Approaches to Assess Dietary Patterns: Hypothesis-Driven and Data-Driven Analysis.

    PubMed

    Previdelli, Ágatha Nogueira; de Andrade, Samantha Caesar; Fisberg, Regina Mara; Marchioni, Dirce Maria

    2016-01-01

    The use of dietary patterns to assess dietary intake has become increasingly common in nutritional epidemiology studies due to the complexity and multidimensionality of the diet. Currently, two main approaches have been widely used to assess dietary patterns: data-driven and hypothesis-driven analysis. Since the methods explore different angles of dietary intake, using both approaches simultaneously might yield complementary and useful information; thus, we aimed to use both approaches to gain knowledge of adolescents' dietary patterns. Food intake from a cross-sectional survey with 295 adolescents was assessed by 24 h dietary recall (24HR). In hypothesis-driven analysis, based on the American National Cancer Institute method, the usual intake of Brazilian Healthy Eating Index Revised components were estimated. In the data-driven approach, the usual intake of foods/food groups was estimated by the Multiple Source Method. In the results, hypothesis-driven analysis showed low scores for Whole grains, Total vegetables, Total fruit and Whole fruits), while, in data-driven analysis, fruits and whole grains were not presented in any pattern. High intakes of sodium, fats and sugars were observed in hypothesis-driven analysis with low total scores for Sodium, Saturated fat and SoFAA (calories from solid fat, alcohol and added sugar) components in agreement, while the data-driven approach showed the intake of several foods/food groups rich in these nutrients, such as butter/margarine, cookies, chocolate powder, whole milk, cheese, processed meat/cold cuts and candies. In this study, using both approaches at the same time provided consistent and complementary information with regard to assessing the overall dietary habits that will be important in order to drive public health programs, and improve their efficiency to monitor and evaluate the dietary patterns of populations. PMID:27669289

  3. Gas-Driven Eruptions, and Speculation for Methane-Driven Ocean Eruptions

    NASA Astrophysics Data System (ADS)

    Zhang, Y.

    2001-12-01

    Brad Sturtevant was a central player in experimental simulations of various types of eruptions, including those driven by the exsolution of gas initially dissolved in a liquid (referred to as gas-driven eruptions, including explosive volcanic eruptions, lake eruptions and eruption of Champagne), and those driven by the evaporation of a liquid (such as geyser eruption, or evaporation waves). The experimental simulations helped to bring together the general understanding of different eruptions. Among gas-driven eruptions, explosive volcanic eruptions are the most familiar and spectacular type. Lake eruptions were recognized only in the 1980's. The underlying principles of the two types of eruptions are similar although there are some difference in the role of the conduit and buoyancy. The main purpose of this report is to speculate on a possible but yet unrecognized type of gas-driven eruptions, methane-driven water eruptions in oceans. In marine sediment, huge amount of CH4 is stored either as gas or as methane hydrate. (The gas pockets might burst, resulting in mud "volcanos".) Under some unusual circumstances such as marine landslides or earthquakes, a large amount of CH4 may be released from sediment to seawater. Depending on the local pressure-temperature conditions, and depending on the kinetics of the various chemical reactions, the released methane gas might lead to gas-driven explosive eruptions. This type of eruptions would be similar to CO2-driven lake eruptions, except that the gas is CH4 instead of CO2. Although no such eruptions have been reported and they are expected to be rare, theoretically they are possible. Because CH4 gas is less dense than air, erupted CH4 gas cloud is expected to rise high into the atmosphere instead of forming ground-hugging flows for CO2 gas flows. Hence the danger to life on the ground is smaller. Satellite imaging might be able to detect such eruptions.

  4. Using Two Different Approaches to Assess Dietary Patterns: Hypothesis-Driven and Data-Driven Analysis

    PubMed Central

    Previdelli, Ágatha Nogueira; de Andrade, Samantha Caesar; Fisberg, Regina Mara; Marchioni, Dirce Maria

    2016-01-01

    The use of dietary patterns to assess dietary intake has become increasingly common in nutritional epidemiology studies due to the complexity and multidimensionality of the diet. Currently, two main approaches have been widely used to assess dietary patterns: data-driven and hypothesis-driven analysis. Since the methods explore different angles of dietary intake, using both approaches simultaneously might yield complementary and useful information; thus, we aimed to use both approaches to gain knowledge of adolescents’ dietary patterns. Food intake from a cross-sectional survey with 295 adolescents was assessed by 24 h dietary recall (24HR). In hypothesis-driven analysis, based on the American National Cancer Institute method, the usual intake of Brazilian Healthy Eating Index Revised components were estimated. In the data-driven approach, the usual intake of foods/food groups was estimated by the Multiple Source Method. In the results, hypothesis-driven analysis showed low scores for Whole grains, Total vegetables, Total fruit and Whole fruits), while, in data-driven analysis, fruits and whole grains were not presented in any pattern. High intakes of sodium, fats and sugars were observed in hypothesis-driven analysis with low total scores for Sodium, Saturated fat and SoFAA (calories from solid fat, alcohol and added sugar) components in agreement, while the data-driven approach showed the intake of several foods/food groups rich in these nutrients, such as butter/margarine, cookies, chocolate powder, whole milk, cheese, processed meat/cold cuts and candies. In this study, using both approaches at the same time provided consistent and complementary information with regard to assessing the overall dietary habits that will be important in order to drive public health programs, and improve their efficiency to monitor and evaluate the dietary patterns of populations. PMID:27669289

  5. Using Two Different Approaches to Assess Dietary Patterns: Hypothesis-Driven and Data-Driven Analysis.

    PubMed

    Previdelli, Ágatha Nogueira; de Andrade, Samantha Caesar; Fisberg, Regina Mara; Marchioni, Dirce Maria

    2016-09-23

    The use of dietary patterns to assess dietary intake has become increasingly common in nutritional epidemiology studies due to the complexity and multidimensionality of the diet. Currently, two main approaches have been widely used to assess dietary patterns: data-driven and hypothesis-driven analysis. Since the methods explore different angles of dietary intake, using both approaches simultaneously might yield complementary and useful information; thus, we aimed to use both approaches to gain knowledge of adolescents' dietary patterns. Food intake from a cross-sectional survey with 295 adolescents was assessed by 24 h dietary recall (24HR). In hypothesis-driven analysis, based on the American National Cancer Institute method, the usual intake of Brazilian Healthy Eating Index Revised components were estimated. In the data-driven approach, the usual intake of foods/food groups was estimated by the Multiple Source Method. In the results, hypothesis-driven analysis showed low scores for Whole grains, Total vegetables, Total fruit and Whole fruits), while, in data-driven analysis, fruits and whole grains were not presented in any pattern. High intakes of sodium, fats and sugars were observed in hypothesis-driven analysis with low total scores for Sodium, Saturated fat and SoFAA (calories from solid fat, alcohol and added sugar) components in agreement, while the data-driven approach showed the intake of several foods/food groups rich in these nutrients, such as butter/margarine, cookies, chocolate powder, whole milk, cheese, processed meat/cold cuts and candies. In this study, using both approaches at the same time provided consistent and complementary information with regard to assessing the overall dietary habits that will be important in order to drive public health programs, and improve their efficiency to monitor and evaluate the dietary patterns of populations.

  6. 3D weighting in cone beam image reconstruction algorithms: ray-driven vs. pixel-driven.

    PubMed

    Tang, Xiangyang; Nilsen, Roy A; Smolin, Alex; Lifland, Ilya; Samsonov, Dmitry; Taha, Basel

    2008-01-01

    A 3D weighting scheme have been proposed previously to reconstruct images at both helical and axial scans in stat-of-the-art volumetric CT scanners for diagnostic imaging. Such a 3D weighting can be implemented in the manner of either ray-driven or pixel-drive, depending on the available computation resources. An experimental study is conducted in this paper to evaluate the difference between the ray-driven and pixel-driven implementations of the 3D weighting from the perspective of image quality, while their computational complexity is analyzed theoretically. Computer simulated data and several phantoms, such as the helical body phantom and humanoid chest phantom, are employed in the experimental study, showing that both the ray-driven and pixel-driven 3D weighting provides superior image quality for diagnostic imaging in clinical applications. With the availability of image reconstruction engine at increasing computational power, it is believed that the pixel-driven 3D weighting will be dominantly employed in state-of-the-art volumetric CT scanners over clinical applications.

  7. Physical Science Informatics: Providing Open Science Access to Microheater Array Boiling Experiment Data

    NASA Technical Reports Server (NTRS)

    McQuillen, John; Green, Robert D.; Henrie, Ben; Miller, Teresa; Chiaramonte, Fran

    2014-01-01

    The Physical Science Informatics (PSI) system is the next step in this an effort to make NASA sponsored flight data available to the scientific and engineering community, along with the general public. The experimental data, from six overall disciplines, Combustion Science, Fluid Physics, Complex Fluids, Fundamental Physics, and Materials Science, will present some unique challenges. Besides data in textual or numerical format, large portions of both the raw and analyzed data for many of these experiments are digital images and video, requiring large data storage requirements. In addition, the accessible data will include experiment design and engineering data (including applicable drawings), any analytical or numerical models, publications, reports, and patents, and any commercial products developed as a result of the research. This objective of paper includes the following: Present the preliminary layout (Figure 2) of MABE data within the PSI database. Obtain feedback on the layout. Present the procedure to obtain access to this database.

  8. Triggering of high-speed neurite outgrowth using an optical microheater

    PubMed Central

    Oyama, Kotaro; Zeeb, Vadim; Kawamura, Yuki; Arai, Tomomi; Gotoh, Mizuho; Itoh, Hideki; Itabashi, Takeshi; Suzuki, Madoka; Ishiwata, Shin’ichi

    2015-01-01

    Optical microheating is a powerful non-invasive method for manipulating biological functions such as gene expression, muscle contraction, and cell excitation. Here, we demonstrate its potential usage for regulating neurite outgrowth. We found that optical microheating with a water-absorbable 1,455-nm laser beam triggers directional and explosive neurite outgrowth and branching in rat hippocampal neurons. The focused laser beam under a microscope rapidly increases the local temperature from 36 °C to 41 °C (stabilized within 2 s), resulting in the elongation of neurites by more than 10 μm within 1 min. This high-speed, persistent elongation of neurites was suppressed by inhibitors of both microtubule and actin polymerization, indicating that the thermosensitive dynamics of these cytoskeletons play crucial roles in this heat-induced neurite outgrowth. Furthermore, we showed that microheating induced the regrowth of injured neurites and the interconnection of neurites. These results demonstrate the efficacy of optical microheating methods for the construction of arbitrary neural networks. PMID:26568288

  9. Light-driven artificial molecular machines

    NASA Astrophysics Data System (ADS)

    Zheng, Yue Bing; Hao, Qingzhen; Yang, Ying-Wei; Kiraly, Brian; Chiang, I.-Kao; Huang, Tony Jun

    2010-08-01

    Artificial molecular machines represent a growing field of nanoscience and nanotechnology. Stimulated by chemical reagents, electricity, or light, artificial molecular machines exhibit precisely controlled motion at the molecular level; with this ability molecular machines have the potential to make significant impacts in numerous engineering applications. Compared with molecular machines powered by chemical or electrical energy, light-driven molecular machines have several advantages: light can be switched much faster, work without producing chemical waste, and be used for dual purposes-inducing (writing) as well as detecting (reading) molecular motions. The following issues are significant for light-driven artificial molecular machines in the following aspects: their chemical structures, motion mechanisms, assembly and characterization on solid-state surfaces. Applications in different fields of nanotechnology such as molecular electronics, nano-electro-mechanical systems (NEMS), nanophotonics, and nanomedicine are envisaged.

  10. Laser-driven fusion etching process

    DOEpatents

    Ashby, C.I.H.; Brannon, P.J.; Gerardo, J.B.

    1987-08-25

    The surfaces of solids are etched by a radiation-driven chemical reaction. The process involves exposing a substrate coated with a layer of a reactant material on its surface to radiation, e.g., a laser, to induce localized melting of the substrate which results in the occurrence of a fusion reaction between the substrate and coating material. The resultant reaction product and excess reactant salt are then removed from the surface of the substrate with a solvent which is relatively inert towards the substrate. The laser-driven chemical etching process is especially suitable for etching ionic substrates, e.g., LiNbO/sub 3/, such as used in electro-optical/acousto-optic devices. It is also suitable for applications wherein the etching process is required to produce an etched ionic substrate having a smooth surface morphology or when a very rapid etching rate is desired.

  11. Laser-driven fusion etching process

    DOEpatents

    Ashby, Carol I. H.; Brannon, Paul J.; Gerardo, James B.

    1989-01-01

    The surfaces of solid ionic substrates are etched by a radiation-driven chemical reaction. The process involves exposing an ionic substrate coated with a layer of a reactant material on its surface to radiation, e.g. a laser, to induce localized melting of the substrate which results in the occurrance of a fusion reaction between the substrate and coating material. The resultant reaction product and excess reactant salt are then removed from the surface of the substrate with a solvent which is relatively inert towards the substrate. The laser-driven chemical etching process is especially suitable for etching ionic salt substrates, e.g., a solid inorganic salt such as LiNbO.sub.3, such as used in electro-optical/acousto-optic devices. It is also suitable for applications wherein the etching process is required to produce an etched ionic substrate having a smooth surface morphology or when a very rapid etching rate is desired.

  12. A signature for turbulence driven magnetic islands

    SciTech Connect

    Agullo, O.; Muraglia, M.; Benkadda, S.; Poyé, A.; Yagi, M.; Garbet, X.; Sen, A.

    2014-09-15

    We investigate the properties of magnetic islands arising from tearing instabilities that are driven by an interchange turbulence. We find that such islands possess a specific signature that permits an identification of their origin. We demonstrate that the persistence of a small scale turbulence maintains a mean pressure profile, whose characteristics makes it possible to discriminate between turbulence driven islands from those arising due to an unfavourable plasma current density gradient. We also find that the island poloidal turnover time, in the steady state, is independent of the levels of the interchange and tearing energy sources. Finally, we show that a mixing length approach is adequate to make theoretical predictions concerning island flattening in the island rotation frame.

  13. Stellar winds driven by Alfven waves

    NASA Technical Reports Server (NTRS)

    Belcher, J. W.; Olbert, S.

    1973-01-01

    Models of stellar winds were considered in which the dynamic expansion of a corona is driven by Alfven waves propagating outward along radial magnetic field lines. In the presence of Alfven waves, a coronal expansion can exist for a broad range of reference conditions which would, in the absence of waves, lead to static configurations. Wind models in which the acceleration mechanism is due to Alfven waves alone and exhibit lower mass fluxes and higher energies per particle are compared to wind models in which the acceleration is due to thermal processes. For example, winds driven by Alfven waves exhibit streaming velocities at infinity which may vary between the escape velocity at the coronal base and the geometrical mean of the escape velocity and the speed of light. Upper and lower limits were derived for the allowed energy fluxes and mass fluxes associated with these winds.

  14. Nova-driven winds in globular clusters

    NASA Technical Reports Server (NTRS)

    Scott, E. H.; Durisen, R. H.

    1978-01-01

    Recent sensitive searches for H-alpha emission from ionized intracluster gas in globular clusters have set upper limits that conflict with theoretical predictions. It is suggested that nova outbursts heat the gas, producing winds that resolve this discrepancy. The incidence of novae in globular clusters, the conversion of kinetic energy of the nova shell to thermal energy of the intracluster gas, and the characteristics of the resultant winds are discussed. Calculated emission from the nova-driven models does not conflict with any observations to date. Some suggestions are made concerning the most promising approaches for future detection of intracluster gas on the basis of these models. The possible relationship of nova-driven winds to globular cluster X-ray sources is also considered.

  15. A charge-driven molecular water pump.

    PubMed

    Gong, Xiaojing; Li, Jingyuan; Lu, Hangjun; Wan, Rongzheng; Li, Jichen; Hu, Jun; Fang, Haiping

    2007-11-01

    Understanding and controlling the transport of water across nanochannels is of great importance for designing novel molecular devices, machines and sensors and has wide applications, including the desalination of seawater. Nanopumps driven by electric or magnetic fields can transport ions and magnetic quanta, but water is charge-neutral and has no magnetic moment. On the basis of molecular dynamics simulations, we propose a design for a molecular water pump. The design uses a combination of charges positioned adjacent to a nanopore and is inspired by the structure of channels in the cellular membrane that conduct water in and out of the cell (aquaporins). The remarkable pumping ability is attributed to the charge dipole-induced ordering of water confined in the nanochannels, where water can be easily driven by external fields in a concerted fashion. These findings may provide possibilities for developing water transport devices that function without osmotic pressure or a hydrostatic pressure gradient.

  16. Control apparatus for hydraulically driven generator

    SciTech Connect

    Beckwith, S.

    1985-08-06

    Apparatus for controlling a hydraulically driven generator for supplying electrical power to power mains. The generator is coupled to a turbine driven by a fluid flow through a duct. The duct has a one-fourth turn butterfly valve controlled by a fluid-actuated operator and the operator receives fluid from the duct by way of a normally closed valve which, when energized, creates water pressure on the operator for opening the butterfly valve. A second, normally open solenoid provides an emergency exit for the water from the operator to relieve the water pressure thereon and thereby close the butterfly valve when certain conditions exist, such as sudden loss of line voltage, overvoltage or deviation in frequency of the line voltage. A differential pressure switch across the turbine rotor also controls the starting of the system to assure proper flow of fluid through the duct before commencing operation of the generator itself.

  17. Solvable model of a strongly driven micromaser

    SciTech Connect

    Lougovski, P.; Walther, H.; Casagrande, F.; Lulli, A.; Englert, B.-G.; Solano, E.

    2004-02-01

    We study the dynamics of a micromaser where the pumping atoms are strongly driven by a resonant classical field during their transit through the cavity mode. We derive a master equation for this strongly driven micromaser, involving the contributions of the unitary atom-field interactions and the dissipative effects of a thermal bath. We find analytical solutions for the temporal evolution and the steady state of this system by means of phase-space techniques, providing an unusual solvable model of an open quantum system, including pumping and decoherence. We derive closed expressions for all relevant expectation values, describing the statistics of the cavity field and the detected atomic levels. The transient regime shows the buildup of mixtures of mesoscopic fields evolving towards a super-Poissonian steady-state field that, nevertheless, yields atomic correlations that exhibit stronger nonclassical features than the conventional micromaser.

  18. A charge-driven molecular water pump.

    PubMed

    Gong, Xiaojing; Li, Jingyuan; Lu, Hangjun; Wan, Rongzheng; Li, Jichen; Hu, Jun; Fang, Haiping

    2007-11-01

    Understanding and controlling the transport of water across nanochannels is of great importance for designing novel molecular devices, machines and sensors and has wide applications, including the desalination of seawater. Nanopumps driven by electric or magnetic fields can transport ions and magnetic quanta, but water is charge-neutral and has no magnetic moment. On the basis of molecular dynamics simulations, we propose a design for a molecular water pump. The design uses a combination of charges positioned adjacent to a nanopore and is inspired by the structure of channels in the cellular membrane that conduct water in and out of the cell (aquaporins). The remarkable pumping ability is attributed to the charge dipole-induced ordering of water confined in the nanochannels, where water can be easily driven by external fields in a concerted fashion. These findings may provide possibilities for developing water transport devices that function without osmotic pressure or a hydrostatic pressure gradient. PMID:18654410

  19. Position Control of Tendon-Driven Fingers

    NASA Technical Reports Server (NTRS)

    Abdallah, Muhammad E.; Platt, Robert, Jr.; Hargrave, B.; Pementer, Frank

    2011-01-01

    Conventionally, tendon-driven manipulators implement some force control scheme based on tension feedback. This feedback allows the system to ensure that the tendons are maintained taut with proper levels of tensioning at all times. Occasionally, whether it is due to the lack of tension feedback or the inability to implement sufficiently high stiffnesses, a position control scheme is needed. This work compares three position controllers for tendon-driven manipulators. A new controller is introduced that achieves the best overall performance with regards to speed, accuracy, and transient behavior. To compensate for the lack of tension feedback, the controller nominally maintains the internal tension on the tendons by implementing a two-tier architecture with a range-space constraint. These control laws are validated experimentally on the Robonaut-2 humanoid hand. I

  20. Wave-driven Countercurrent Plasma Centrifuge

    SciTech Connect

    A.J. Fetterman and N.J. Fisch

    2009-03-20

    A method for driving rotation and a countercurrent flow in a fully ionized plasma centrifuge is described. The rotation is produced by radiofrequency waves near the cyclotron resonance. The wave energy is transferred into potential energy in a manner similar to the α channeling effect. The countercurrent flow may also be driven by radiofrequency waves. By driving both the rotation and the flow pattern using waves instead of electrodes, physical and engineering issues may be avoided.

  1. Scaling the electromagnetically driven explosive shock simulator

    NASA Technical Reports Server (NTRS)

    Persh, Robert I.

    1987-01-01

    A heavy payload electromagnetically driven explosive shock simulator, referred to as EDESS-3, has been assembled and characterized at the Navel research Weapons Center. EDESS-3 is the logical outgrowth of the earlier EDESS 1 and 2 simulator work which explored the use of electrical pulse power technology for the generation of explosive like shocks. The features of the EDESS-3 are presented, and designs for the next generation of EDESS machines are introduced.

  2. Chaos control of parametric driven Duffing oscillators

    SciTech Connect

    Jin, Leisheng; Mei, Jie; Li, Lijie

    2014-03-31

    Duffing resonators are typical dynamic systems, which can exhibit chaotic oscillations, subject to certain driving conditions. Chaotic oscillations of resonating systems with negative and positive spring constants are identified to investigate in this paper. Parametric driver imposed on these two systems affects nonlinear behaviours, which has been theoretically analyzed with regard to variation of driving parameters (frequency, amplitude). Systematic calculations have been performed for these two systems driven by parametric pumps to unveil the controllability of chaos.

  3. Electrically Driven Technologies for Radioactive Aerosol Abatement

    SciTech Connect

    David W. DePaoli; Ofodike A. Ezekoye; Costas Tsouris; Valmor F. de Almeida

    2003-01-28

    The purpose of this research project was to develop an improved understanding of how electriexecy driven processes, including electrocoalescence, acoustic agglomeration, and electric filtration, may be employed to efficiently treat problems caused by the formation of aerosols during DOE waste treatment operations. The production of aerosols during treatment and retrieval operations in radioactive waste tanks and during thermal treatment operations such as calcination presents a significant problem of cost, worker exposure, potential for release, and increased waste volume.

  4. A User Driven Dynamic Circuit Network Implementation

    SciTech Connect

    Guok, Chin; Robertson, David; Chaniotakis, Evangelos; Thompson, Mary; Johnston, William; Tierney, Brian

    2008-10-01

    The requirements for network predictability are becoming increasingly critical to the DoE science community where resources are widely distributed and collaborations are world-wide. To accommodate these emerging requirements, the Energy Sciences Network has established a Science Data Network to provide user driven guaranteed bandwidth allocations. In this paper we outline the design, implementation, and secure coordinated use of such a network, as well as some lessons learned.

  5. Tuned, driven, and active soft matter

    NASA Astrophysics Data System (ADS)

    Menzel, Andreas M.

    2015-02-01

    One characteristic feature of soft matter systems is their strong response to external stimuli. As a consequence they are comparatively easily driven out of their ground state and out of equilibrium, which leads to many of their fascinating properties. Here, we review illustrative examples. This review is structured by an increasing distance from the equilibrium ground state. On each level, examples of increasing degree of complexity are considered. In detail, we first consider systems that are quasi-statically tuned or switched to a new state by applying external fields. These are common liquid crystals, liquid crystalline elastomers, or ferrogels and magnetic elastomers. Next, we concentrate on systems steadily driven from outside e.g. by an imposed flow field. In our case, we review the reaction of nematic liquid crystals, of bulk-filling periodically modulated structures such as block copolymers, and of localized vesicular objects to an imposed shear flow. Finally, we focus on systems that are "active" and "self-driven". Here our range spans from idealized self-propelled point particles, via sterically interacting particles like granular hoppers, via microswimmers such as self-phoretically driven artificial Janus particles or biological microorganisms, via deformable self-propelled particles like droplets, up to the collective behavior of insects, fish, and birds. As we emphasize, similarities emerge in the features and behavior of systems that at first glance may not necessarily appear related. We thus hope that our overview will further stimulate the search for basic unifying principles underlying the physics of these soft materials out of their equilibrium ground state.

  6. Renormalization in Periodically Driven Quantum Dots.

    PubMed

    Eissing, A K; Meden, V; Kennes, D M

    2016-01-15

    We report on strong renormalization encountered in periodically driven interacting quantum dots in the nonadiabatic regime. Correlations between lead and dot electrons enhance or suppress the amplitude of driving depending on the sign of the interaction. Employing a newly developed flexible renormalization-group-based approach for periodic driving to an interacting resonant level we show analytically that the magnitude of this effect follows a power law. Our setup can act as a non-Markovian, single-parameter quantum pump. PMID:26824557

  7. Ontology-driven health information systems architectures.

    PubMed

    Blobel, Bernd; Oemig, Frank

    2009-01-01

    Following an architecture vision such as the Generic Component Model (GCM) architecture framework, health information systems for supporting personalized care have to be based on a component-oriented architecture. Representing concepts and their interrelations, the GCM perspectives system architecture, domains, and development process can be described by the domains' ontologies. The paper introduces ontology principles, ontology references to the GCM as well as some practical aspects of ontology-driven approaches to semantically interoperable and sustainable health information systems.

  8. A Precession-Driven Lunar Dynamo

    NASA Astrophysics Data System (ADS)

    Tian, B. Y.; Stanley, S.; Tikoo, S. M.; Weiss, B. P.

    2014-12-01

    Paleomagnetic studies of Apollo samples suggest that the Moon generated a magnetic field with surface field intensities of several tens of microteslas until at least 3.56 billion years ago (Ga). The field then declined by an order of magnitude from 3.56 - 3.19 Ga. Because of difficulties in reproducing such a long-lived and intense field with convection-driven dynamos, a dynamo driven by precession of the mantle relative to the core was proposed as an alternative. However, there have not been any detailed numerical models demonstrating the feasibility, lifetime, and intensity of such a lunar dynamo. Using fully 3D magnetohydrodynamic simulations, we determined the strength and duration of a mechanically-driven dynamo powered by mantle precession. We found that this mechanism was capable of not only generating the 10-100μT paleomagnetic intensities observed in Apollo samples aged between 4.25 and 3.56 Ga, but also reproducing the precipitous decline in paleointensity beyond 3.56 Ga as the obliquity of the Moon decreased below 15°.

  9. Epidemic cycles driven by host behaviour.

    PubMed

    Althouse, Benjamin M; Hébert-Dufresne, Laurent

    2014-10-01

    Host immunity and demographics (the recruitment of susceptibles via birthrate) have been demonstrated to be a key determinant of the periodicity of measles, pertussis and dengue epidemics. However, not all epidemic cycles are from pathogens inducing sterilizing immunity or are driven by demographics. Many sexually transmitted infections are driven by sexual behaviour. We present a mathematical model of disease transmission where individuals can disconnect and reconnect depending on the infectious status of their contacts. We fit the model to historic syphilis (Treponema pallidum) and gonorrhea (Neisseria gonorrhoeae) incidence in the USA and explore potential intervention strategies against syphilis. We find that cycles in syphilis incidence can be driven solely by changing sexual behaviour in structured populations. Our model also explains the lack of similar cycles in gonorrhea incidence even if the two infections share the same propagation pathways. Our model similarly illustrates how sudden epidemic outbreaks can occur on time scales smaller than the characteristic demographic time scale of the population and that weaker infections can lead to more violent outbreaks. Behaviour also appears to be critical for control strategies as we found a bigger sensitivity to behavioural interventions than antibiotic treatment. Thus, behavioural interventions may play a larger role than previously thought, especially in the face of antibiotic resistance and low intervention efficacies. PMID:25100316

  10. Electrically Driven Liquid Film Boiling Experiment

    NASA Technical Reports Server (NTRS)

    Didion, Jeffrey R.

    2016-01-01

    This presentation presents the science background and ground based results that form the basis of the Electrically Driven Liquid Film Boiling Experiment. This is an ISS experiment that is manifested for 2021. Objective: Characterize the effects of gravity on the interaction of electric and flow fields in the presence of phase change specifically pertaining to: a) The effects of microgravity on the electrically generated two-phase flow. b) The effects of microgravity on electrically driven liquid film boiling (includes extreme heat fluxes). Electro-wetting of the boiling section will repel the bubbles away from the heated surface in microgravity environment. Relevance/Impact: Provides phenomenological foundation for the development of electric field based two-phase thermal management systems leveraging EHD, permitting optimization of heat transfer surface area to volume ratios as well as achievement of high heat transfer coefficients thus resulting in system mass and volume savings. EHD replaces buoyancy or flow driven bubble removal from heated surface. Development Approach: Conduct preliminary experiments in low gravity and ground-based facilities to refine technique and obtain preliminary data for model development. ISS environment required to characterize electro-wetting effect on nucleate boiling and CHF in the absence of gravity. Will operate in the FIR - designed for autonomous operation.

  11. Dissipative adaptation in driven self-assembly

    NASA Astrophysics Data System (ADS)

    England, Jeremy L.

    2015-11-01

    In a collection of assembling particles that is allowed to reach thermal equilibrium, the energy of a given microscopic arrangement and the probability of observing the system in that arrangement obey a simple exponential relationship known as the Boltzmann distribution. Once the same thermally fluctuating particles are driven away from equilibrium by forces that do work on the system over time, however, it becomes significantly more challenging to relate the likelihood of a given outcome to familiar thermodynamic quantities. Nonetheless, it has long been appreciated that developing a sound and general understanding of the thermodynamics of such non-equilibrium scenarios could ultimately enable us to control and imitate the marvellous successes that living things achieve in driven self-assembly. Here, I suggest that such a theoretical understanding may at last be emerging, and trace its development from historic first steps to more recent discoveries. Focusing on these newer results, I propose that they imply a general thermodynamic mechanism for self-organization via dissipation of absorbed work that may be applicable in a broad class of driven many-body systems.

  12. A gasdynamic gun driven by gaseous detonation.

    PubMed

    Li, Jinping; Chen, Hong; Zhang, Shizhong; Zhang, Xiaoyuan; Yu, Hongru

    2016-01-01

    A gasdynamic gun driven by gaseous detonation was developed to address the disadvantages of the insufficient driving capability of high-pressure gas and the constraints of gunpowder. The performance of this gasdynamic gun was investigated through experiments and numerical simulations. Much more powerful launching capability was achieved by this gun relative to a conventional high-pressure gas gun, owing to the use of the chemical energy of the driver gas. To achieve the same launching condition, the initial pressure required for this gun was an order of magnitude lower than that for a gun driven by high-pressure H2. Because of the presence of the detonation, however, a more complex internal ballistic process of this gun was observed. Acceleration of projectiles for this gun was accompanied by a series of impulse loads, in contrast with the smooth acceleration for a conventional one, which indicates that this gun should be used conditionally. The practical feasibility of this gun was verified by experiments. The experiments demonstrated the convenience of taking advantage of the techniques developed for detonation-driven shock tubes and tunnels. PMID:26827358

  13. A Climate Driven Speleothem Stable Isotope Model

    NASA Astrophysics Data System (ADS)

    Shorey, C. V.; Gonzalez, L. A.

    2004-12-01

    We have constructed a climate driven stalagmite growth model that faithfully reproduces the major annual growth trends of temperate climate stalagmites. Model results indicate that speleothem growth rate in temperate regions, although depending primarily on precipitation amount, is a complex function of the timing of precipitation relative to seasonal temperature changes as well as other non-climatic parameters. We have incorporated into this climate driven growth model the capability to simulate climate driven carbon and oxygen stable isotope changes and their incorporation in speleothem calcite. The model allows us to investigate the relationship between isotopic changes in soil CO2 and seepage fluids, and the isotopic composition of the growing stalagmite. We also explore the impact of sampling resolution on the extracted speleothem isotope record. We calibrated the model to replicate the growth and isotopic record of a stalagmite collected in 1982 from Mystery Cave State Park, in Southeastern Minnesota and using temperature and precipitation records spanning 1935-1982 from a nearby weather station. The model generally replicates the \\delta13C and \\delta18O record for this case. Model ouput indicates that that large deviations of temperature or precipitation from average conditions in a single year can be recorded in speleothems. Increases in temperature have a clear postive correlation with \\delta13C values, and a less direct negative correlation with \\delta18O values. Increases in precipitation have an inconsistent positive correlation with \\delta13C values and a clear positive correlation with \\delta18O values.

  14. A gasdynamic gun driven by gaseous detonation.

    PubMed

    Li, Jinping; Chen, Hong; Zhang, Shizhong; Zhang, Xiaoyuan; Yu, Hongru

    2016-01-01

    A gasdynamic gun driven by gaseous detonation was developed to address the disadvantages of the insufficient driving capability of high-pressure gas and the constraints of gunpowder. The performance of this gasdynamic gun was investigated through experiments and numerical simulations. Much more powerful launching capability was achieved by this gun relative to a conventional high-pressure gas gun, owing to the use of the chemical energy of the driver gas. To achieve the same launching condition, the initial pressure required for this gun was an order of magnitude lower than that for a gun driven by high-pressure H2. Because of the presence of the detonation, however, a more complex internal ballistic process of this gun was observed. Acceleration of projectiles for this gun was accompanied by a series of impulse loads, in contrast with the smooth acceleration for a conventional one, which indicates that this gun should be used conditionally. The practical feasibility of this gun was verified by experiments. The experiments demonstrated the convenience of taking advantage of the techniques developed for detonation-driven shock tubes and tunnels.

  15. A gasdynamic gun driven by gaseous detonation

    NASA Astrophysics Data System (ADS)

    Li, Jinping; Chen, Hong; Zhang, Shizhong; Zhang, Xiaoyuan; Yu, Hongru

    2016-01-01

    A gasdynamic gun driven by gaseous detonation was developed to address the disadvantages of the insufficient driving capability of high-pressure gas and the constraints of gunpowder. The performance of this gasdynamic gun was investigated through experiments and numerical simulations. Much more powerful launching capability was achieved by this gun relative to a conventional high-pressure gas gun, owing to the use of the chemical energy of the driver gas. To achieve the same launching condition, the initial pressure required for this gun was an order of magnitude lower than that for a gun driven by high-pressure H2. Because of the presence of the detonation, however, a more complex internal ballistic process of this gun was observed. Acceleration of projectiles for this gun was accompanied by a series of impulse loads, in contrast with the smooth acceleration for a conventional one, which indicates that this gun should be used conditionally. The practical feasibility of this gun was verified by experiments. The experiments demonstrated the convenience of taking advantage of the techniques developed for detonation-driven shock tubes and tunnels.

  16. Magnetic Control of Solutal Buoyancy Driven Convection

    NASA Technical Reports Server (NTRS)

    Ramachandran, N.; Leslie, F. W.

    2003-01-01

    Volumetric forces resulting from local density variations and gravitational acceleration cause buoyancy induced convective motion in melts and solutions. Solutal buoyancy is a result of concentration differences in an otherwise isothermal fluid. If the fluid also exhibits variations in magnetic susceptibility with concentration then convection control by external magnetic fields can be hypothesized. Magnetic control of thermal buoyancy induced convection in ferrofluids (dispersions of ferromagnetic particles in a carrier fluid) and paramagnetic fluids have been demonstrated. Here we show the nature of magnetic control of solutal buoyancy driven convection of a paramagnetic fluid, an aqueous solution of Manganese Chloride hydrate. We predict the critical magnetic field required for balancing gravitational solutal buoyancy driven convection and validate it through a simple experiment. We demonstrate that gravity driven flow can be completely reversed by a magnetic field but the exact cancellation of the flow is not possible. This is because the phenomenon is unstable. The technique can be applied to crystal growth processes in order to reduce convection and to heat exchanger devices for enhancing convection. The method can also be applied to impose a desired g-level in reduced gravity applications.

  17. Epidemic cycles driven by host behaviour

    PubMed Central

    Althouse, Benjamin M.; Hébert-Dufresne, Laurent

    2014-01-01

    Host immunity and demographics (the recruitment of susceptibles via birthrate) have been demonstrated to be a key determinant of the periodicity of measles, pertussis and dengue epidemics. However, not all epidemic cycles are from pathogens inducing sterilizing immunity or are driven by demographics. Many sexually transmitted infections are driven by sexual behaviour. We present a mathematical model of disease transmission where individuals can disconnect and reconnect depending on the infectious status of their contacts. We fit the model to historic syphilis (Treponema pallidum) and gonorrhea (Neisseria gonorrhoeae) incidence in the USA and explore potential intervention strategies against syphilis. We find that cycles in syphilis incidence can be driven solely by changing sexual behaviour in structured populations. Our model also explains the lack of similar cycles in gonorrhea incidence even if the two infections share the same propagation pathways. Our model similarly illustrates how sudden epidemic outbreaks can occur on time scales smaller than the characteristic demographic time scale of the population and that weaker infections can lead to more violent outbreaks. Behaviour also appears to be critical for control strategies as we found a bigger sensitivity to behavioural interventions than antibiotic treatment. Thus, behavioural interventions may play a larger role than previously thought, especially in the face of antibiotic resistance and low intervention efficacies. PMID:25100316

  18. 46 CFR 169.623 - Power-driven steering systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Power-driven steering systems. 169.623 Section 169.623... Machinery and Electrical Steering Systems § 169.623 Power-driven steering systems. (a) Power-driven steering... system must automatically resume operation after an electric power outage. (b) Control of...

  19. Current-Driven Filament Instabilities in Relativistic Plasmas. Final report

    SciTech Connect

    Ren, Chuang

    2013-02-13

    This grant has supported a study of some fundamental problems in current- and flow-driven instabilities in plasmas and their applications in inertial confinement fusion (ICF) and astrophysics. It addressed current-driven instabilities and their roles in fast ignition, and flow-driven instabilities and their applications in astrophysics.

  20. 30 CFR 77.407 - Power-driven pulleys.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Power-driven pulleys. 77.407 Section 77.407... for Mechanical Equipment § 77.407 Power-driven pulleys. (a) Belts, chains, and ropes shall not be guided onto power-driven moving pulleys, sprockets, or drums with the hands except on slow...

  1. 30 CFR 75.1728 - Power-driven pulleys.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Power-driven pulleys. 75.1728 Section 75.1728... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1728 Power-driven pulleys. (a) Belts, chains, and ropes shall not be guided onto power-driven moving pulleys, sprockets, or drums with...

  2. 30 CFR 75.1728 - Power-driven pulleys.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Power-driven pulleys. 75.1728 Section 75.1728... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1728 Power-driven pulleys. (a) Belts, chains, and ropes shall not be guided onto power-driven moving pulleys, sprockets, or drums with...

  3. 14 CFR 25.1127 - Exhaust driven turbo-superchargers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Exhaust driven turbo-superchargers. 25.1127 Section 25.1127 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... driven turbo-superchargers. (a) Each exhaust driven turbo-supercharger must be approved or shown to...

  4. 14 CFR 25.1127 - Exhaust driven turbo-superchargers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Exhaust driven turbo-superchargers. 25.1127 Section 25.1127 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... driven turbo-superchargers. (a) Each exhaust driven turbo-supercharger must be approved or shown to...

  5. 30 CFR 75.1728 - Power-driven pulleys.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Power-driven pulleys. 75.1728 Section 75.1728... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1728 Power-driven pulleys. (a) Belts, chains, and ropes shall not be guided onto power-driven moving pulleys, sprockets, or drums with...

  6. 46 CFR 169.623 - Power-driven steering systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Power-driven steering systems. 169.623 Section 169.623... Machinery and Electrical Steering Systems § 169.623 Power-driven steering systems. (a) Power-driven steering... system must automatically resume operation after an electric power outage. (b) Control of...

  7. 14 CFR 25.1127 - Exhaust driven turbo-superchargers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Exhaust driven turbo-superchargers. 25.1127 Section 25.1127 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... driven turbo-superchargers. (a) Each exhaust driven turbo-supercharger must be approved or shown to...

  8. 30 CFR 77.407 - Power-driven pulleys.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Power-driven pulleys. 77.407 Section 77.407... for Mechanical Equipment § 77.407 Power-driven pulleys. (a) Belts, chains, and ropes shall not be guided onto power-driven moving pulleys, sprockets, or drums with the hands except on slow...

  9. 30 CFR 75.1728 - Power-driven pulleys.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Power-driven pulleys. 75.1728 Section 75.1728... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1728 Power-driven pulleys. (a) Belts, chains, and ropes shall not be guided onto power-driven moving pulleys, sprockets, or drums with...

  10. 30 CFR 77.407 - Power-driven pulleys.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Power-driven pulleys. 77.407 Section 77.407... for Mechanical Equipment § 77.407 Power-driven pulleys. (a) Belts, chains, and ropes shall not be guided onto power-driven moving pulleys, sprockets, or drums with the hands except on slow...

  11. 30 CFR 77.407 - Power-driven pulleys.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Power-driven pulleys. 77.407 Section 77.407... for Mechanical Equipment § 77.407 Power-driven pulleys. (a) Belts, chains, and ropes shall not be guided onto power-driven moving pulleys, sprockets, or drums with the hands except on slow...

  12. 46 CFR 169.623 - Power-driven steering systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Power-driven steering systems. 169.623 Section 169.623... Machinery and Electrical Steering Systems § 169.623 Power-driven steering systems. (a) Power-driven steering... system must automatically resume operation after an electric power outage. (b) Control of...

  13. 30 CFR 75.1728 - Power-driven pulleys.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Power-driven pulleys. 75.1728 Section 75.1728... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1728 Power-driven pulleys. (a) Belts, chains, and ropes shall not be guided onto power-driven moving pulleys, sprockets, or drums with...

  14. 46 CFR 169.623 - Power-driven steering systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Power-driven steering systems. 169.623 Section 169.623... Machinery and Electrical Steering Systems § 169.623 Power-driven steering systems. (a) Power-driven steering... system must automatically resume operation after an electric power outage. (b) Control of...

  15. 14 CFR 25.1127 - Exhaust driven turbo-superchargers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Exhaust driven turbo-superchargers. 25.1127 Section 25.1127 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... driven turbo-superchargers. (a) Each exhaust driven turbo-supercharger must be approved or shown to...

  16. 30 CFR 77.407 - Power-driven pulleys.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Power-driven pulleys. 77.407 Section 77.407... for Mechanical Equipment § 77.407 Power-driven pulleys. (a) Belts, chains, and ropes shall not be guided onto power-driven moving pulleys, sprockets, or drums with the hands except on slow...

  17. 14 CFR 25.1127 - Exhaust driven turbo-superchargers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Exhaust driven turbo-superchargers. 25.1127 Section 25.1127 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... driven turbo-superchargers. (a) Each exhaust driven turbo-supercharger must be approved or shown to...

  18. 46 CFR 169.623 - Power-driven steering systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Power-driven steering systems. 169.623 Section 169.623... Machinery and Electrical Steering Systems § 169.623 Power-driven steering systems. (a) Power-driven steering... system must automatically resume operation after an electric power outage. (b) Control of...

  19. What we learn from surveillance testing of standby turbine driven and motor driven pumps

    SciTech Connect

    Christie, B.

    1996-12-01

    This paper describes a comparison of the performance information collected by the author and the respective system engineers from five standby turbine driven pumps at four commercial nuclear electric generating units in the United States and from two standby motor driven pumps at two of these generating units. Information was collected from surveillance testing and from Non-Test actuations. Most of the performance information (97%) came from surveillance testing. {open_quotes}Conditional Probabilities{close_quotes} of the pumps ability to respond to a random demand were calculated for each of the seven standby pumps and compared to the historical record of the Non-Test actuations. It appears that the Conditional Probabilities are comparable to the rate of success for Non-Test actuations. The Conditional Probabilities of the standby motor driven pumps (approximately 99%) are better than the Conditional Probabilities of the standby turbine driven pumps (82%-96% range). Recommendations were made to improve the Conditional Probabilities of the standby turbine driven pumps.

  20. 14 CFR 36.9 - Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes. 36.9 Section 36.9 Aeronautics and Space FEDERAL... AIRWORTHINESS CERTIFICATION General § 36.9 Acoustical change: Propeller-driven small airplanes and...

  1. 14 CFR 36.9 - Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes. 36.9 Section 36.9 Aeronautics and Space FEDERAL... AIRWORTHINESS CERTIFICATION General § 36.9 Acoustical change: Propeller-driven small airplanes and...

  2. 14 CFR 36.9 - Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes. 36.9 Section 36.9 Aeronautics and Space FEDERAL... AIRWORTHINESS CERTIFICATION General § 36.9 Acoustical change: Propeller-driven small airplanes and...

  3. 14 CFR 36.9 - Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes. 36.9 Section 36.9 Aeronautics and Space FEDERAL... AIRWORTHINESS CERTIFICATION General § 36.9 Acoustical change: Propeller-driven small airplanes and...

  4. 14 CFR 36.9 - Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes. 36.9 Section 36.9 Aeronautics and Space FEDERAL... AIRWORTHINESS CERTIFICATION General § 36.9 Acoustical change: Propeller-driven small airplanes and...

  5. Gear-driven draw works have high reliability

    SciTech Connect

    Heinrichs, P. )

    1995-02-20

    Gear-driven draw works have several advantages over conventional chain-driven draw works. Gear-driven draw works have a longer life and working availability (reliability) than chain-driven units, and these factors lead to lower operating costs because of fewer rig shut downs for repairs. The gear shift allows higher speeds and a better adaptation to the performance curve for greater operational efficiency. Additionally, more variable speed selection is possible with direct shifting from 1st to 4th speed. On failure of a gear shift, operation can be continued, with reduced performance, with the autodriller which is integrated directly into the gear shift. Additionally, the gear-driven unit makes less noise and vibration and has a compact construction for reduced weight. The oldest gear-driven draw works have been in use without any gear failure for 27 years, and other gear-driven draw works have worked for many years with no failure.

  6. Transmission with two parallel driving shafts bearing two driving gears each meshed with same driven gear on parallel driven shaft

    SciTech Connect

    Akashi, T.; Ito, H.; Yamada, S.

    1986-06-17

    A transmission mechanism for a vehicle is described for receiving input of rotational power from a power supply member which rotates in a particular rotational direction and for outputting rotational power to a power receiving member which includes: an input member connected to the power supply member and which is rotatably mounted and receives supplying of the rotational power from the power supply member; a first driving gear wheel shaft; a second driving gear wheel shaft mounted generally parallel to the first driving gear wheel shaft; a driven gear wheel shaft mounted generally parallel to the first and second driving gear wheel shafts, the driven gear wheel shaft being rotationally connected to the power receiving member; a first driven gear wheel fixedly mounted on the driven gear wheel shaft; a first driving gear wheel which is rotatably mounted on the first driving gear wheel shaft and is constant mesh with the driven gear wheel, the first driving and driven gear wheels providing a first reduction gear ratio from the first driving gear wheel shaft to the driven gear wheel shaft; a second driven gear wheel fixedly mounted on the driven gear wheel shaft; a second driving gear wheel which is rotatably mounted on the second driving gear wheel shaft and is in constant mesh with the first driven gear wheel, the second driving and the first driven gear wheels providing a second reduction gear ratio smaller than the first reduction gear ratio from the second driving gear wheel shaft to the driven gear wheel shaft; a third driving gear wheel which is rotatably mounted on the first driving gear wheel shaft and is in constant mesh with the second driven gear wheel, the third driving and the second driven gear wheels providing a third reduction gear ratio smaller than the second reduction gear ratio from the first driving gear wheel shaft to the driven gear wheel shaft.

  7. Screw dislocation driven growth of nanomaterials.

    PubMed

    Meng, Fei; Morin, Stephen A; Forticaux, Audrey; Jin, Song

    2013-07-16

    Nanoscience and nanotechnology impact our lives in many ways, from electronic and photonic devices to biosensors. They also hold the promise of tackling the renewable energy challenges facing us. However, one limiting scientific challenge is the effective and efficient bottom-up synthesis of nanomaterials. We can approach this core challenge in nanoscience and nanotechnology from two perspectives: (a) how to controllably grow high-quality nanomaterials with desired dimensions, morphologies, and material compositions and (b) how to produce them in a large quantity at reasonable cost. Because many chemical and physical properties of nanomaterials are size- and shape-dependent, rational syntheses of nanomaterials to achieve desirable dimensionalities and morphologies are essential to exploit their utilities. In this Account, we show that the dislocation-driven growth mechanism, where screw dislocation defects provide self-perpetuating growth steps to enable the anisotropic growth of various nanomaterials at low supersaturation, can be a powerful and versatile synthetic method for a wide variety of nanomaterials. Despite significant progress in the last two decades, nanomaterial synthesis has often remained an "art", and except for a few well-studied model systems, the growth mechanisms of many anisotropic nanostructures remain poorly understood. We strive to go beyond the empirical science ("cook-and-look") and adopt a fundamental and mechanistic perspective to the anisotropic growth of nanomaterials by first understanding the kinetics of the crystal growth process. Since most functional nanomaterials are in single-crystal form, insights from the classical crystal growth theories are crucial. We pay attention to how screw dislocations impact the growth kinetics along different crystallographic directions and how the strain energy of defected crystals influences their equilibrium shapes. Furthermore, such inquiries are supported by detailed structural investigation to

  8. Hysteresis in Pressure-Driven DNA Denaturation

    PubMed Central

    Hernández-Lemus, Enrique; Nicasio-Collazo, Luz Adriana; Castañeda-Priego, Ramón

    2012-01-01

    In the past, a great deal of attention has been drawn to thermal driven denaturation processes. In recent years, however, the discovery of stress-induced denaturation, observed at the one-molecule level, has revealed new insights into the complex phenomena involved in the thermo-mechanics of DNA function. Understanding the effect of local pressure variations in DNA stability is thus an appealing topic. Such processes as cellular stress, dehydration, and changes in the ionic strength of the medium could explain local pressure changes that will affect the molecular mechanics of DNA and hence its stability. In this work, a theory that accounts for hysteresis in pressure-driven DNA denaturation is proposed. We here combine an irreversible thermodynamic approach with an equation of state based on the Poisson-Boltzmann cell model. The latter one provides a good description of the osmotic pressure over a wide range of DNA concentrations. The resulting theoretical framework predicts, in general, the process of denaturation and, in particular, hysteresis curves for a DNA sequence in terms of system parameters such as salt concentration, density of DNA molecules and temperature in addition to structural and configurational states of DNA. Furthermore, this formalism can be naturally extended to more complex situations, for example, in cases where the host medium is made up of asymmetric salts or in the description of the (helical-like) charge distribution along the DNA molecule. Moreover, since this study incorporates the effect of pressure through a thermodynamic analysis, much of what is known from temperature-driven experiments will shed light on the pressure-induced melting issue. PMID:22496765

  9. Metabolic Dependencies in RAS-Driven Cancers.

    PubMed

    Kimmelman, Alec C

    2015-04-15

    The ability to inhibit the RAS oncogene has been the holy grail of oncology because of the critical role of this gene in a multitude of tumor types. In addition, RAS-mutant tumors are among the most aggressive and refractory to treatment. Although directly targeting the RAS oncogene has proven challenging, an alternative approach for treating RAS-driven cancers is to inhibit critical downstream events that are required for tumor maintenance. Indeed, much focus has been put on inhibiting signaling cascades downstream of RAS. Recent studies have shown that oncogenic RAS promotes a metabolic reprogramming of tumor cells, shifting them toward an anabolic metabolism necessary to produce biomass to support unconstrained proliferation. These cancers also use a diverse set of fuel sources to meet their metabolic needs and have even developed a variety of mechanisms to act as metabolic scavengers to obtain necessary metabolic substrates from both extracellular and intracellular sources. Collectively, these adaptations can create "metabolic bottlenecks" whereby tumor cells rely on particular pathways or rate-limiting metabolites. In this regard, inhibiting individual or combinations of these metabolic pathways can attenuate growth in preclinical models. Because these dependencies are tumor selective and downstream of oncogenic RAS, there is the opportunity for therapeutic intervention. Although targeting tumor metabolism is still in the early days of translation to patients, our continued advances in understanding critical metabolic adaptations in RAS-driven cancers, as well as the ability to study this altered metabolism in relevant tumor models, will accelerate the development of new therapeutic approaches. Clin Cancer Res; 21(8); 1828-34. ©2015 AACR. See all articles in this CCR Focus section, "Targeting RAS-Driven Cancers." PMID:25878364

  10. A Model-Driven Sensor Web Simulator

    NASA Astrophysics Data System (ADS)

    Burns, R. W.

    2008-12-01

    Although numerous strides in weather forecasting were achieved in the past forty years, many of the operational concepts for today's observing systems remain essentially unchanged. Improvements have been suggested to address this, particularly the use of a model-driven sensor web architecture. Such a sensor web would potentially consist of ground systems, weather models, sensors and other components. The sensor web would enable cooperative, real-time measurements and targeted observations that can be used to improve operational efficiency and the forecast model's predictive skill. Implementing such a sensor web system, however, would impose significant costs and risks. Therefore, NASA Goddard is developing a tool called the Sensor Web Simulator. This tool is designed to simulate the behavior of a real-world, model-driven sensor web. The simulator leverages technology from Observing System Simulation Experiments (OSSEs) to create simulated observations for the desired observing platforms. Through the use of a workflow tool and data services, the Sensor Web Simulator integrates multiple models and software components and allows users to configure options and then execute a sensor web scenario. Although the work is in its early stages, the potential for its benefits have already been demonstrated. An initial experiment using sensor web concepts shows how a model-driven operations concept with the GWOS lidar could minimize the required number of lidar shots without compromising the information of the model's atmospheric state. Future work on the Sensor Web Simulator was proposed to expand the system beyond a "breadboard" system of components into an integrated mission design tool for scientists and engineers.

  11. Precessionally driven dynamos in ellipsoidal geometry

    NASA Astrophysics Data System (ADS)

    Ernst-Hullermann, J.; Harder, H.; Hansen, U.

    2013-12-01

    Precession was suggested as an alternative driving mechanism for Earth's and planetary magnetic fields by Bullard in 1949. Recent estimates of the thermal and electrical conductivity of Earth's core even show that the energy budget for buoyancy driven dynamos might be very tight. Therefore it seems worth to consider precession at least as an additional if not the only source of energy for the geodynamo. We are going to investigate precessionally driven dynamos by the use of a Finite Volume code. As precession drives a flow only due to the movement of the boundaries the shape of the container is essential for the character of the flow. In planets, it is much more effective to drive a precessional flow by the pressure differences induced by the topography of the precessing body rather than by viscous coupling to the walls. Numerical simulations are the only method offering the possibility to investigate the influence of the topography since laboratory experiments normally are constrained by the predetermined geometry of the vessel. We discuss how ellipticity of the planets can be included in our simulations by the use of a non-orthogonal grid. We will show that even laminar precession-driven flows are capable to generate a magnetic field. Most of the magnetic energy of this dynamos resides in the outer viscous boundary layer. While at lower Ekman number the kinematic dynamos also have magnetic fields located in the bulk, these diminish in the full magneto-hydrodynamic case. The laminar dynamos may not scale to Earth-like parameters. Nevertheless, with our new method we have the possibility to explore the parameter space much more systematically.

  12. Pressure-Driven Flow of Solid Helium

    SciTech Connect

    Day, James; Beamish, John

    2006-03-17

    The recent torsional oscillator results of Kim and Chan show an anomalous mass decoupling, interpreted by the authors as a supersolid phase transition, in solid {sup 4}He. We have used a piezoelectrically driven diaphragm to study the flow of solid helium through an array of capillaries. Our measurements showed no indication of low temperature flow, placing stringent restrictions on supersolid flow in response to a pressure difference. The average flow speed at low temperatures was less than 1.2x10{sup -14} m/s, corresponding to a supersolid velocity at least 7 orders of magnitude smaller than the critical velocities inferred from the torsional oscillator measurements.

  13. Energy-beam-driven rapid fabrication system

    DOEpatents

    Keicher, David M.; Atwood, Clinton L.; Greene, Donald L.; Griffith, Michelle L.; Harwell, Lane D.; Jeantette, Francisco P.; Romero, Joseph A.; Schanwald, Lee P.; Schmale, David T.

    2002-01-01

    An energy beam driven rapid fabrication system, in which an energy beam strikes a growth surface to form a molten puddle thereon. Feed powder is then injected into the molten puddle from a converging flow of feed powder. A portion of the feed powder becomes incorporated into the molten puddle, forcing some of the puddle contents to freeze on the growth surface, thereby adding an additional layer of material. By scanning the energy beam and the converging flow of feed powder across the growth surface, complex three-dimensional shapes can be formed, ready or nearly ready for use. Nearly any class of material can be fabricated using this system.

  14. Convection-driven tectonics on Venus

    NASA Astrophysics Data System (ADS)

    Phillips, R. J.

    1990-02-01

    An analysis is presented of convective stress coupling to an elastic lithosphere as applied to Venus. Theoretical solutions are introduced for the response of a mathematically thick elastic plate overlying a Newtonian viscous medium with an exponential depth dependence of viscosity, and a Green's function solution is obtained for the viscous flow driven by a harmonic density distribution at a specified depth. An elastic-plastic analysis is carried out for the deformation of a model Venus lithosphere. The results predict that dynamic uplift of Venusian topography must be accompanied by extensive brittle failure and viscous flow in the lithosphere.

  15. Diagnostics for Respondent-driven Sampling

    PubMed Central

    2016-01-01

    Summary Respondent-driven sampling (RDS) is a widely used method for sampling from hard-to-reach human populations, especially populations at higher risk for HIV. Data are collected through peer-referral over social networks. RDS has proven practical for data collection in many difficult settings and is widely used. Inference from RDS data requires many strong assumptions because the sampling design is partially beyond the control of the researcher and partially unobserved. We introduce diagnostic tools for most of these assumptions and apply them in 12 high risk populations. These diagnostics empower researchers to better understand their data and encourage future statistical research on RDS. PMID:27226702

  16. Granular transport in driven granular gas.

    PubMed

    Noirhomme, M; Opsomer, E; Vandewalle, N; Ludewig, F

    2015-02-01

    We numerically and theoretically investigate the behavior of a granular gas driven by asymmetric plates. The injection of energy in the dissipative system differs from one side to the opposite one. We prove that the dynamical clustering which is expected for such a system is affected by the asymmetry. As a consequence, the cluster position can be fully controlled. This property could lead to various applications in the handling of granular materials in low-gravity environment. Moreover, the dynamical cluster is characterized by natural oscillations which are also captured by a model. These oscillations are mainly related to the cluster size, thus providing an original way to probe the clustering behavior.

  17. Four-level refrigerator driven by photons

    NASA Astrophysics Data System (ADS)

    Wang, Jianhui; Lai, Yiming; Ye, Zhuolin; He, Jizhou; Ma, Yongli; Liao, Qinghong

    2015-05-01

    We propose a quantum absorption refrigerator driven by photons. The model uses a four-level system as its working substance and couples simultaneously to hot, cold, and solar heat reservoirs. Explicit expressions for the cooling power Q˙c and coefficient of performance (COP) ηCOP are derived, with the purpose of revealing and optimizing the performance of the device. Our model runs most efficiently under the tight coupling condition, and it is consistent with the third law of thermodynamics in the limit T →0 .

  18. Magnon-driven quantum dot refrigerators

    NASA Astrophysics Data System (ADS)

    Wang, Yuan; Huang, Chuankun; Liao, Tianjun; Chen, Jincan

    2015-12-01

    A new model of refrigerator consisting of a spin-splitting quantum dot coupled with two ferromagnetic reservoirs and a ferromagnetic insulator is proposed. The rate equation is used to calculate the occupation probabilities of the quantum dot. The expressions of the electron and magnon currents are obtained. The region that the system can work in as a refrigerator is determined. The cooling power and coefficient of performance (COP) of the refrigerator are derived. The influences of the magnetic field, applied voltage, and polarization of two leads on the performance are discussed. The performances of two different magnon-driven quantum dot refrigerators are compared.

  19. Hopf bifurcation in the driven cavity

    NASA Technical Reports Server (NTRS)

    Goodrich, John W.; Gustafson, Karl; Halasi, Kadosa

    1990-01-01

    The algorithm employed in the present incompressible two-dimensional calculations of an impulsively-started lid-driven cavity has its basis in the time-dependent stream-function equation. While a Crank-Nicholson differencing scheme is used for the diffusion terms, the Adams-Bashforth scheme is used for the convection terms. The periodic asymptotic solutions obtained for Reynolds numbers of 5000 and 10,000 are found to be precisely periodic; it is demonstrated that they have reached asymptotic states. The indicators of that achievement are discussed.

  20. Accelerator driven sub-critical core

    SciTech Connect

    McIntyre, Peter M; Sattarov, Akhdiyor

    2015-03-17

    Systems and methods for operating an accelerator driven sub-critical core. In one embodiment, a fission power generator includes a sub-critical core and a plurality of proton beam generators. Each of the proton beam generators is configured to concurrently provide a proton beam into a different area of the sub-critical core. Each proton beam scatters neutrons within the sub-critical core. The plurality of proton beam generators provides aggregate power to the sub-critical core, via the proton beams, to scatter neutrons sufficient to initiate fission in the sub-critical core.

  1. Surface Tension Driven Convection Experiment Completed

    NASA Technical Reports Server (NTRS)

    Jacobson, Thomas P.; Sedlak, Deborah A.

    1997-01-01

    The Surface Tension Driven Convection Experiment (STDCE) was designed to study basic fluid mechanics and heat transfer on thermocapillary flows generated by temperature variations along the free surfaces of liquids in microgravity. STDCE first flew on the USML-1 mission in July 1992 and was rebuilt for the USML-2 mission that was launched in October 1995. This was a collaborative project with principal investigators from Case Western Reserve University (CWRU), Professors Simon Ostrach and Yasuhiro Kamotani, along with a team from the NASA Lewis Research Center composed of civil servants and contractors from Aerospace Design & Fabrication, Inc. (ADF), Analex, and NYMA, Inc.

  2. Four-level refrigerator driven by photons.

    PubMed

    Wang, Jianhui; Lai, Yiming; Ye, Zhuolin; He, Jizhou; Ma, Yongli; Liao, Qinghong

    2015-05-01

    We propose a quantum absorption refrigerator driven by photons. The model uses a four-level system as its working substance and couples simultaneously to hot, cold, and solar heat reservoirs. Explicit expressions for the cooling power Q̇(c) and coefficient of performance (COP) η(COP) are derived, with the purpose of revealing and optimizing the performance of the device. Our model runs most efficiently under the tight coupling condition, and it is consistent with the third law of thermodynamics in the limit T→0. PMID:26066099

  3. Neutrino physics with accelerator driven subcritical reactors

    NASA Astrophysics Data System (ADS)

    Ciuffoli, Emilio; Evslin, Jarah; Zhao, Fengyi

    2016-01-01

    Accelerator driven system (ADS) subcritical nuclear reactors are under development around the world. They will be intense sources of free, 30-55 MeV μ + decay at rest {overline{ν}}_{μ } . These ADS reactor neutrinos can provide a robust test of the LSND anomaly and a precise measurement of the leptonic CP-violating phase δ, including sign(cos(δ)). The first phase of many ADS programs includes the construction of a low energy, high intensity proton or deuteron accelerator, which can yield competitive bounds on sterile neutrinos.

  4. Parametrically driven surface waves on viscous ferrofluids

    NASA Astrophysics Data System (ADS)

    Müller, Hanns Walter

    1998-11-01

    Standing waves on the surface of a ferrofluid in a normal magnetic field can be excited by a vertical vibration of the container. A stability theory for the onset of these parametrically driven waves is developed, taking viscous dissipation and finite depth effects into account. It will be shown that a careful choice of the filling level permits the normal and anomalous dispersion branches to be measured. Furthermore it will be demonstrated that the parametric driving mechanism may lead to a delay of the Rosensweig instability. A bicritical situation can be achieved when Rosensweig and Faraday waves interact.

  5. RF Driven Multicusp H- Ion Source

    SciTech Connect

    Leung, K.N.; DeVries, G.J.; DiVergilio, W.F.; Hamm, R.W.; Hauck, C.A.; Kunkel, W.B.; McDonald, D.S.; Williams, M.D.

    1990-06-01

    An rf driven multicusp source capable of generating 1-ms H{sup -} beam pulses with a repetition rate as high as 150 Hz has been developed. This source can be operated with a filament or other types of starter. There is almost no lifetime limitation and a clean plasma can be maintained for a long period of operation. It is demonstrated that rf power as high as 25 kW could be coupled inductively to the plasma via a glass-coated copper-coil antenna. The extracted H{sup -} current density achieved is about 200 mA/cm{sup 2}.

  6. Diffusion Driven Combustion Waves in Porous Media

    NASA Technical Reports Server (NTRS)

    Aldushin, A. P.; Matkowsky, B. J.

    2000-01-01

    Filtration of gas containing oxidizer, to the reaction zone in a porous medium, due, e.g., to a buoyancy force or to an external pressure gradient, leads to the propagation of Filtration combustion (FC) waves. The exothermic reaction occurs between the fuel component of the solid matrix and the oxidizer. In this paper, we analyze the ability of a reaction wave to propagate in a porous medium without the aid of filtration. We find that one possible mechanism of propagation is that the wave is driven by diffusion of oxidizer from the environment. The solution of the combustion problem describing diffusion driven waves is similar to the solution of the Stefan problem describing the propagation of phase transition waves, in that the temperature on the interface between the burned and unburned regions is constant, the combustion wave is described by a similarity solution which is a function of the similarity variable x/square root of(t) and the wave velocity decays as 1/square root of(t). The difference between the two problems is that in the combustion problem the temperature is not prescribed, but rather, is determined as part of the solution. We will show that the length of samples in which such self-sustained combustion waves can occur, must exceed a critical value which strongly depends on the combustion temperature T(sub b). Smaller values of T(sub b) require longer sample lengths for diffusion driven combustion waves to exist. Because of their relatively small velocity, diffusion driven waves are considered to be relevant for the case of low heat losses, which occur for large diameter samples or in microgravity conditions, Another possible mechanism of porous medium combustion describes waves which propagate by consuming the oxidizer initially stored in the pores of the sample. This occurs for abnormally high pressure and gas density. In this case, uniformly propagating planar waves, which are kinetically controlled, can propagate, Diffusion of oxidizer decreases

  7. Optimality of Contraction-Driven Crawling

    NASA Astrophysics Data System (ADS)

    Recho, P.; Joanny, J.-F.; Truskinovsky, L.

    2014-05-01

    We study a particular mechanism of cell motility allowing a precise formulation of the condition of optimal trade-off between performance and metabolic cost. In the model, a steadily crawling fragment is represented by a layer of active gel placed on a frictional surface and driven by contraction only. We find analytically the distribution of contractile elements (pullers) ensuring that the efficiency of self-propulsion is maximal. We then show that natural assumptions about advection and diffusion of pullers produce a distribution that is remarkably close to the optimal one and is qualitatively similar to the one observed in experiments on fish keratocytes.

  8. Advanced motor driven clamped borehole seismic receiver

    DOEpatents

    Engler, Bruce P.; Sleefe, Gerard E.; Striker, Richard P.

    1993-01-01

    A borehole seismic tool including a borehole clamp which only moves perpendicular to the borehole. The clamp is driven by an electric motor, via a right angle drive. When used as a seismic receiver, the tool has a three part housing, two of which are hermetically sealed. Accelerometers or geophones are mounted in one hermetically sealed part, the electric meter in the other hermetically sealed part, and the clamp and right angle drive in the third part. Preferably the tool includes cable connectors at both ends. Optionally a shear plate can be added to the clamp to extend the range of the tool.

  9. Advanced motor driven clamped borehole seismic receiver

    DOEpatents

    Engler, B.P.; Sleefe, G.E.; Striker, R.P.

    1993-02-23

    A borehole seismic tool is described including a borehole clamp which only moves perpendicular to the borehole. The clamp is driven by an electric motor, via a right angle drive. When used as a seismic receiver, the tool has a three part housing, two of which are hermetically sealed. Accelerometers or geophones are mounted in one hermetically sealed part, the electric motor in the other hermetically sealed part, and the clamp and right angle drive in the third part. Preferably the tool includes cable connectors at both ends. Optionally a shear plate can be added to the clamp to extend the range of the tool.

  10. Odd-frequency superconductivity in driven systems

    NASA Astrophysics Data System (ADS)

    Triola, Christopher; Balatsky, Alexander V.

    2016-09-01

    We show that Berezinskii's classification of the symmetries of Cooper pair amplitudes holds for driven systems even in the absence of translation invariance. We then consider a model Hamiltonian for a superconductor coupled to an external driving potential and, treating the drive as a perturbation, we investigate the corrections to the anomalous Green's function, density of states, and spectral function. We find that in the presence of an external drive the anomalous Green's function develops terms that are odd in frequency and that the same mechanism responsible for these odd-frequency terms generates additional features in the density of states and spectral function.

  11. Arc-driven rail accelerator research

    NASA Technical Reports Server (NTRS)

    Ray, Pradosh K.

    1987-01-01

    Arc-driven rail accelerator research is analyzed by considering wall ablation and viscous drag in the plasma. Plasma characteristics are evaluated through a simple fluid-mechanical analysis considering only wall ablation. By equating the energy dissipated in the plasma with the radiation heat loss, the average properties of the plasma are determined as a function of time and rate of ablation. Locations of two simultaneously accelerating arcs were determined by optical and magnetic probes and fron streak camera photographs. All three measurements provide consistent results.

  12. Molecular propellers and tunneling-driven motors

    NASA Astrophysics Data System (ADS)

    Vukovic, Lela; Wang, Boyang; Kral, Petr

    2008-03-01

    We design molecular propellers with carbon nanotube rotors and aromatic blades that allow selective pumping of hydrophobic and hydrophilic liquids [1]. Our molecular dynamics studies show that the pumping efficiency strongly depends on the chemistry of the liquid-blade interface. We also discuss several prototypes of highly efficient molecular motors driven by electron tunneling that could drive such rotary molecular machines [2]. These systems might pump liquids and provide motility at the nanoscale. [1] B. Wang and P. Kr'al, Phys. Rev. Lett. 98, 266102 (2007). [2] L. Vukovic, B. Wang and P. Kr'al, submitted.

  13. An artificial heart driven by liquid gas.

    PubMed

    Abe, Y; Chinzei, T; Imachi, K; Mabuchi, K; Atsumi, K; Fujimasa, I

    1990-01-01

    An artificial heart (AH) driving system, in which a sac or diaphragm type blood pump is liquid gas driven, is designed. The working mechanism of this system is as follows: 1) liquid gas is used for the driving source; 2) a liquid gas is stored in its liquid state in the circuit; 3) a liquid gas is vaporized, and the vaporizing pressure squeezes the blood pump, causing ejection of blood; 4) vaporized gas is aspirated and compressed by a small compressor to liquefaction through the heat exchanger, then negative pressure is applied to the blood pump and blood is aspirated; and 5) the blood pump is driven in this closed cycle. To demonstrate the mechanism of this system, a prototype was developed using Freon 114 as the liquid gas. In this system, the maximum flow of the AH at a 100 pulse per minute rate, was about 6.9 L/min, using a 90 ml sac type blood pump. The advantages of this AH driving mechanism are as follows: 1) a small system is available because pressure chambers are not necessary; 2) a biventricular system is available, with a single compressor; 3) no compliance chamber is necessary if the system is small enough to be implanted.

  14. Skyrmion motion driven by oscillating magnetic field

    PubMed Central

    Moon, Kyoung-Woong; Kim, Duck-Ho; Je, Soong-Geun; Chun, Byong Sun; Kim, Wondong; Qiu, Z.Q.; Choe, Sug-Bong; Hwang, Chanyong

    2016-01-01

    The one-dimensional magnetic skyrmion motion induced by an electric current has attracted much interest because of its application potential in next-generation magnetic memory devices. Recently, the unidirectional motion of large (20 μm in diameter) magnetic bubbles with two-dimensional skyrmion topology, driven by an oscillating magnetic field, has also been demonstrated. For application in high-density memory devices, it is preferable to reduce the size of skyrmion. Here we show by numerical simulation that a skyrmion of a few tens of nanometres can also be driven by high-frequency field oscillations, but with a different direction of motion from the in-plane component of the tilted oscillating field. We found that a high-frequency field for small skyrmions can excite skyrmion resonant modes and that a combination of different modes results in a final skyrmion motion with a helical trajectory. Because this helical motion depends on the frequency of the field, we can control both the speed and the direction of the skyrmion motion, which is a distinguishable characteristic compared with other methods. PMID:26847334

  15. Flux-driven simulations of turbulence collapse

    SciTech Connect

    Park, G. Y.; Kim, S. S.; Jhang, Hogun; Rhee, T.; Diamond, P. H.; Xu, X. Q.

    2015-03-15

    Using three-dimensional nonlinear simulations of tokamak turbulence, we show that an edge transport barrier (ETB) forms naturally once input power exceeds a threshold value. Profiles, turbulence-driven flows, and neoclassical coefficients are evolved self-consistently. A slow power ramp-up simulation shows that ETB transition is triggered by the turbulence-driven flows via an intermediate phase which involves coherent oscillation of turbulence intensity and E×B flow shear. A novel observation of the evolution is that the turbulence collapses and the ETB transition begins when R{sub T} > 1 at t = t{sub R} (R{sub T}: normalized Reynolds power), while the conventional transition criterion (ω{sub E×B}>γ{sub lin} where ω{sub E×B} denotes mean flow shear) is satisfied only after t = t{sub C} ( >t{sub R}), when the mean flow shear grows due to positive feedback.

  16. Periodically driven three-level systems

    NASA Astrophysics Data System (ADS)

    Kenmoe, M. B.; Fai, L. C.

    2016-09-01

    We study the dynamics of a three-level system (ThLS) sinusoidally driven in both longitudinal and transverse directions and in the presence of a uniaxial anisotropy D entering the generic Hamiltonian through the zero-energy splitting term D (Sz)2 where Sz is the projection of the spin vector along the quantization direction. As a consequence of the addition of this term, the order of the symmetry group of the Hamiltonian is increased by a unit and we observe a sequence of cascaded SU(3) Landau-Zener-Stückelberg-Majorana (LZSM) interferometers. The study is carried out by analytically and numerically calculating the probabilities of nonadiabatic and adiabatic evolutions. For nonadiabatic evolutions, two main approximations based on the weak and strong driving limits are discussed by comparing the characteristic frequency of the longitudinal drive with the amplitudes of driven fields. For each of the cases discussed, our analytical results quite well reproduce the gross temporal profile of the exact numerical probabilities. This allows us to check the range of validity of analytical results and confirm our assumptions. For adiabatic evolutions, a general theory is constructed allowing for the description of adiabatic passages in arbitrary ThLSs in which direct transitions between states with extremal spin projections are forbidden. A compact formula for adiabatic evolutions is derived and numerically tested for some illustrative cases. Interference patterns demonstrating multiple LZSM transitions are reported. Applications of our results to the nitrogen vacancy center in diamond are discussed.

  17. Skyrmion motion driven by oscillating magnetic field

    NASA Astrophysics Data System (ADS)

    Moon, Kyoung-Woong; Kim, Duck-Ho; Je, Soong-Geun; Chun, Byong Sun; Kim, Wondong; Qiu, Z. Q.; Choe, Sug-Bong; Hwang, Chanyong

    2016-02-01

    The one-dimensional magnetic skyrmion motion induced by an electric current has attracted much interest because of its application potential in next-generation magnetic memory devices. Recently, the unidirectional motion of large (20 μm in diameter) magnetic bubbles with two-dimensional skyrmion topology, driven by an oscillating magnetic field, has also been demonstrated. For application in high-density memory devices, it is preferable to reduce the size of skyrmion. Here we show by numerical simulation that a skyrmion of a few tens of nanometres can also be driven by high-frequency field oscillations, but with a different direction of motion from the in-plane component of the tilted oscillating field. We found that a high-frequency field for small skyrmions can excite skyrmion resonant modes and that a combination of different modes results in a final skyrmion motion with a helical trajectory. Because this helical motion depends on the frequency of the field, we can control both the speed and the direction of the skyrmion motion, which is a distinguishable characteristic compared with other methods.

  18. Data-driven array architectures: a rebirth?

    NASA Astrophysics Data System (ADS)

    Cardoso, Joao M. P.

    2005-06-01

    The von Neumann-style architectures have been tremendously well succeeded by taking advantage of the Moore"s law. It is now understood that, it will be very difficult to meet the supercomputing demands of the future computing systems with this style of microprocessor architectures. Most nowadays applications require high-performance for processing data streams. Being dataflow computing a natural paradigm to process data streams, architectures based on dataflow principles are emerging as a way to meet the supercomputing demands. Data-driven arrays, introduced in the 80"s, are examples of such architectures. They devised a scalable and effective fashion to directly support the dataflow model of computation and have been revived by a number of reconfigurable architectures (e.g., KressArray, WaveScalar, and XPP). Those coarse-grained reconfigurable architectures with dataflow semantics depict interesting achievements with respect to performance and programming methodologies, when compared to other computing platforms. This paper presents the most interesting data-driven array architectures. Trends and open issues related to a number of properties at architectural level and to compilation techniques are enumerated and discussed. A number of features are illustrated, especially the support for hardware virtualization, speculative configuration, and software pipelining. Examples using the PACT XPP reconfigurable array are shown. Those examples include the ADPCM decoder, from the MediaBench repository, and LeeDCT, an optimized DCT algorithm.

  19. Microwave Driven Actuators Power Allocation and Distribution

    NASA Technical Reports Server (NTRS)

    Forbes, Timothy; Song, Kyo D.

    2000-01-01

    Design, fabrication and test of a power allocation and distribution (PAD) network for microwave driven actuators is presented in this paper. Development of a circuit that would collect power from a rectenna array amplify and distribute the power to actuators was designed and fabricated for space application in an actuator array driven by a microwave. A P-SPICE model was constructed initially for data reduction purposes, and was followed by a working real-world model. A voltage up - converter (VUC) is used to amplify the voltage from the individual rectenna. The testing yielded a 26:1 voltage amplification ratio with input voltage at 9 volts and a measured output voltage 230VDC. Future work includes the miniaturization of the circuitry, the use of microwave remote control, and voltage amplification technology for each voltage source. The objective of this work is to develop a model system that will collect DC voltage from an array of rectenna and propagate the voltage to an array of actuators.

  20. Test Driven Development of Scientific Models

    NASA Technical Reports Server (NTRS)

    Clune, Thomas L.

    2012-01-01

    Test-Driven Development (TDD) is a software development process that promises many advantages for developer productivity and has become widely accepted among professional software engineers. As the name suggests, TDD practitioners alternate between writing short automated tests and producing code that passes those tests. Although this overly simplified description will undoubtedly sound prohibitively burdensome to many uninitiated developers, the advent of powerful unit-testing frameworks greatly reduces the effort required to produce and routinely execute suites of tests. By testimony, many developers find TDD to be addicting after only a few days of exposure, and find it unthinkable to return to previous practices. Of course, scientific/technical software differs from other software categories in a number of important respects, but I nonetheless believe that TDD is quite applicable to the development of such software and has the potential to significantly improve programmer productivity and code quality within the scientific community. After a detailed introduction to TDD, I will present the experience within the Software Systems Support Office (SSSO) in applying the technique to various scientific applications. This discussion will emphasize the various direct and indirect benefits as well as some of the difficulties and limitations of the methodology. I will conclude with a brief description of pFUnit, a unit testing framework I co-developed to support test-driven development of parallel Fortran applications.

  1. Progress of Laser-Driven Plasma Accelerators

    SciTech Connect

    Nakajima, Kazuhisa

    2007-07-11

    There is a great interest worldwide in plasma accelerators driven by ultra-intense lasers which make it possible to generate ultra-high gradient acceleration and high quality particle beams in a much more compact size compared with conventional accelerators. A frontier research on laser and plasma accelerators is focused on high energy electron acceleration and ultra-short X-ray and Tera Hertz radiations as their applications. These achievements will provide not only a wide range of sciences with benefits of a table-top accelerator but also a basic science with a tool of ultrahigh energy accelerators probing an unknown extremely microscopic world.Harnessing the recent advance of ultra-intense ultra-short pulse lasers, the worldwide research has made a tremendous breakthrough in demonstrating high-energy high-quality particle beams in a compact scale, so called ''dream beams on a table top'', which represents monoenergetic electron beams from laser wakefield accelerators and GeV acceleration by capillary plasma-channel laser wakefield accelerators. This lecture reviews recent progress of results on laser-driven plasma based accelerator experiments to quest for particle acceleration physics in intense laser-plasma interactions and to present new outlook for the GeV-range high-energy laser plasma accelerators.

  2. Development of an electrically driven molecular motor.

    PubMed

    Murphy, Colin J; Sykes, E Charles H

    2014-10-01

    For molecules to be used as components in molecular machinery, methods are required that couple individual molecules to external energy sources in order to selectively excite motion in a given direction. While significant progress has been made in the construction of synthetic molecular motors powered by light and by chemical reactions, there are few experimental examples of electrically driven molecular motors. To this end, we pioneered the use of a new, stable and tunable molecular rotor system based on surface-bound thioethers to comprehensively study many aspects of molecular rotation. As biological molecular motors often operate at interfaces, our synthetic system is especially amenable to microscopic interrogation as compared to solution-based systems. Using scanning tunneling microscopy (STM) and density functional theory, we studied the rotation of surface-bound thioethers, which can be induced either thermally or by electrons from the STM tip in a two-terminal setup. Moreover, the temperature and electron flux can be adjusted to allow each rotational event to be monitored at the molecular scale in real time. This work culminated in the first experimental demonstration of a single-molecule electric motor, where the electrically driven rotation of a butyl methyl sulfide molecule adsorbed on a copper surface could be directionally biased. The direction and rate of the rotation are related to the chirality of both the molecule and the STM tip (which serves as the electrode), illustrating the importance of the symmetry of the metal contacts in atomic-scale electrical devices.

  3. Accelerating Science Driven System Design With RAMP

    SciTech Connect

    Wawrzynek, John

    2015-05-01

    Researchers from UC Berkeley, in collaboration with the Lawrence Berkeley National Lab, are engaged in developing an Infrastructure for Synthesis with Integrated Simulation (ISIS). The ISIS Project was a cooperative effort for “application-driven hardware design” that engages application scientists in the early parts of the hardware design process for future generation supercomputing systems. This project served to foster development of computing systems that are better tuned to the application requirements of demanding scientific applications and result in more cost-effective and efficient HPC system designs. In order to overcome long conventional design-cycle times, we leveraged reconfigurable devices to aid in the design of high-efficiency systems, including conventional multi- and many-core systems. The resulting system emulation/prototyping environment, in conjunction with the appropriate intermediate abstractions, provided both a convenient user programming experience and retained flexibility, and thus efficiency, of a reconfigurable platform. We initially targeted the Berkeley RAMP system (Research Accelerator for Multiple Processors) as that hardware emulation environment to facilitate and ultimately accelerate the iterative process of science-driven system design. Our goal was to develop and demonstrate a design methodology for domain-optimized computer system architectures. The tangible outcome is a methodology and tools for rapid prototyping and design-space exploration, leading to highly optimized and efficient HPC systems.

  4. Piezoelectric driven thermo-acoustic refrigerator

    NASA Astrophysics Data System (ADS)

    Chinn, D. G.; Nouh, M.; Aldraihem, O.; Baz, A.

    2011-03-01

    Thermoacoustic refrigeration is an emerging refrigeration technology which does not rely for in its operation on the use of any moving parts or harmful refrigerants. This technology uses acoustic waves to pump heat across a temperature gradient. The vast majority of thermoacoustic refrigerators to date have used electromagnetic loudspeakers to generate the acoustic input. In this paper, the design, construction, operation, and modeling of a piezoelectric-driven thermoacoustic refrigerator are detailed. This refrigerator demonstrates the effectiveness of piezoelectric actuation in moving 0.3 W of heat across an 18 degree C temperature difference with an input power of 7.6 W. The performance characteristics of this class of thermoacoustic-piezoelectric refrigerator are modeled using DeltaEC software and the predictions are validated experimentally. The obtained results confirm the validity of the developed model. Furthermore, the potential of piezoelectric actuation as effective means for driving thermoacoustic refrigerators is demonstrated as compared to the conventional electromagnetic loudspeakers which are heavy and require high actuation energy. The developed theoretical and experimental tools can serve as invaluable means for the design and testing of other piezoelectric driven thermoacoustic refrigerator configurations.

  5. Temporal percolation in activity-driven networks

    NASA Astrophysics Data System (ADS)

    Starnini, Michele; Pastor-Satorras, Romualdo

    2014-03-01

    We study the temporal percolation properties of temporal networks by taking as a representative example the recently proposed activity-driven-network model [N. Perra et al., Sci. Rep. 2, 469 (2012), 10.1038/srep00469]. Building upon an analytical framework based on a mapping to hidden variables networks, we provide expressions for the percolation time Tp marking the onset of a giant connected component in the integrated network. In particular, we consider both the generating function formalism, valid for degree-uncorrelated networks, and the general case of networks with degree correlations. We discuss the different limits of the two approaches, indicating the parameter regions where the correlated threshold collapses onto the uncorrelated case. Our analytical predictions are confirmed by numerical simulations of the model. The temporal percolation concept can be fruitfully applied to study epidemic spreading on temporal networks. We show in particular how the susceptible-infected-removed model on an activity-driven network can be mapped to the percolation problem up to a time given by the spreading rate of the epidemic process. This mapping allows us to obtain additional information on this process, not available for previous approaches.

  6. An artificial heart driven by liquid gas.

    PubMed

    Abe, Y; Chinzei, T; Imachi, K; Mabuchi, K; Atsumi, K; Fujimasa, I

    1990-01-01

    An artificial heart (AH) driving system, in which a sac or diaphragm type blood pump is liquid gas driven, is designed. The working mechanism of this system is as follows: 1) liquid gas is used for the driving source; 2) a liquid gas is stored in its liquid state in the circuit; 3) a liquid gas is vaporized, and the vaporizing pressure squeezes the blood pump, causing ejection of blood; 4) vaporized gas is aspirated and compressed by a small compressor to liquefaction through the heat exchanger, then negative pressure is applied to the blood pump and blood is aspirated; and 5) the blood pump is driven in this closed cycle. To demonstrate the mechanism of this system, a prototype was developed using Freon 114 as the liquid gas. In this system, the maximum flow of the AH at a 100 pulse per minute rate, was about 6.9 L/min, using a 90 ml sac type blood pump. The advantages of this AH driving mechanism are as follows: 1) a small system is available because pressure chambers are not necessary; 2) a biventricular system is available, with a single compressor; 3) no compliance chamber is necessary if the system is small enough to be implanted. PMID:2252673

  7. Accelerator-driven X-ray Sources

    SciTech Connect

    Nguyen, Dinh Cong

    2015-11-09

    After an introduction which mentions x-ray tubes and storage rings and gives a brief review of special relativity, the subject is treated under the following topics and subtopics: synchrotron radiation (bending magnet radiation, wiggler radiation, undulator radiation, brightness and brilliance definition, synchrotron radiation facilities), x-ray free-electron lasers (linac-driven X-ray FEL, FEL interactions, self-amplified spontaneous emission (SASE), SASE self-seeding, fourth-generation light source facilities), and other X-ray sources (energy recovery linacs, Inverse Compton scattering, laser wakefield accelerator driven X-ray sources. In summary, accelerator-based light sources cover the entire electromagnetic spectrum. Synchrotron radiation (bending magnet, wiggler and undulator radiation) has unique properties that can be tailored to the users’ needs: bending magnet and wiggler radiation is broadband, undulator radiation has narrow spectral lines. X-ray FELs are the brightest coherent X-ray sources with high photon flux, femtosecond pulses, full transverse coherence, partial temporal coherence (SASE), and narrow spectral lines with seeding techniques. New developments in electron accelerators and radiation production can potentially lead to more compact sources of coherent X-rays.

  8. Science Goal Driven Observing and Spacecraft Autonomy

    NASA Technical Reports Server (NTRS)

    Koratkar, Amuradha; Grosvenor, Sandy; Jones, Jeremy; Wolf, Karl

    2002-01-01

    Spacecraft autonomy will be an integral part of mission operations in the coming decade. While recent missions have made great strides in the ability to autonomously monitor and react to changing health and physical status of spacecraft, little progress has been made in responding quickly to science driven events. For observations of inherently variable targets and targets of opportunity, the ability to recognize early if an observation will meet the science goals of a program, and react accordingly, can have a major positive impact on the overall scientific returns of an observatory and on its operational costs. If the onboard software can reprioritize the schedule to focus on alternate targets, discard uninteresting observations prior to downloading, or download a subset of observations at a reduced resolution, the spacecraft's overall efficiency will be dramatically increased. The science goal monitoring (SGM) system is a proof-of-concept effort to address the above challenge. The SGM will have an interface to help capture higher level science goals from the scientists and translate them into a flexible observing strategy that SGM can execute and monitor. We are developing an interactive distributed system that will use on-board processing and storage combined with event-driven interfaces with ground-based processing and operations, to enable fast re-prioritization of observing schedules, and to minimize time spent on non-optimized observations.

  9. Radiatively Driven Turbulence at the Cloud Top

    NASA Astrophysics Data System (ADS)

    de Lozar, Alberto; Mellado, Juan Pedro

    2012-11-01

    We use Direct Numerical Simulations to investigate a radiatively-driven smoke cloud-top mixing layer. This configuration mimics relevant aspects of stratocumuls clouds, in particular the mixing across an inversion that bounds a radiatively driven turbulent flow. A 1D formulation is employed for the radiation calculations. Below the inversion a convective boundary layer propagates downwards into the cloud-bulk. The convective boundary layer decouples from the inversion properties other than the injected buoyancy flux. This buoyancy flux is equal to the total radiative cooling minus the cooling of the inversion layer where the cloud mixes with the free atmosphere. An exact equation at a properly defined inversion point divides the inversion cooling into three components: a molecular flux, a turbulent flux and the direct radiative cooling by the smoke inside the inversion layer. The normalized turbulent flux levels to a constant value (0 . 175 +/- 0 . 05), which is independent of the stratification. As suggested by earlies studies, we observe that the turbulent entrainment only occurs at the small scales and that eddies larger than four optical lengths (50 m in a typical DYCOMS-II cloud) perform little or no entrainment.

  10. Bleb-driven chemotaxis of Dictyostelium cells

    PubMed Central

    Zatulovskiy, Evgeny; Tyson, Richard; Bretschneider, Till

    2014-01-01

    Blebs and F-actin–driven pseudopods are alternative ways of extending the leading edge of migrating cells. We show that Dictyostelium cells switch from using predominantly pseudopods to blebs when migrating under agarose overlays of increasing stiffness. Blebs expand faster than pseudopods leaving behind F-actin scars, but are less persistent. Blebbing cells are strongly chemotactic to cyclic-AMP, producing nearly all of their blebs up-gradient. When cells re-orientate to a needle releasing cyclic-AMP, they stereotypically produce first microspikes, then blebs and pseudopods only later. Genetically, blebbing requires myosin-II and increases when actin polymerization or cortical function is impaired. Cyclic-AMP induces transient blebbing independently of much of the known chemotactic signal transduction machinery, but involving PI3-kinase and downstream PH domain proteins, CRAC and PhdA. Impairment of this PI3-kinase pathway results in slow movement under agarose and cells that produce few blebs, though actin polymerization appears unaffected. We propose that mechanical resistance induces bleb-driven movement in Dictyostelium, which is chemotactic and controlled through PI3-kinase. PMID:24616222

  11. Stochastic Event-Driven Molecular Dynamics

    SciTech Connect

    Donev, Aleksandar Garcia, Alejandro L.; Alder, Berni J.

    2008-02-01

    A novel Stochastic Event-Driven Molecular Dynamics (SEDMD) algorithm is developed for the simulation of polymer chains suspended in a solvent. SEDMD combines event-driven molecular dynamics (EDMD) with the Direct Simulation Monte Carlo (DSMC) method. The polymers are represented as chains of hard-spheres tethered by square wells and interact with the solvent particles with hard-core potentials. The algorithm uses EDMD for the simulation of the polymer chain and the interactions between the chain beads and the surrounding solvent particles. The interactions between the solvent particles themselves are not treated deterministically as in EDMD, rather, the momentum and energy exchange in the solvent is determined stochastically using DSMC. The coupling between the solvent and the solute is consistently represented at the particle level retaining hydrodynamic interactions and thermodynamic fluctuations. However, unlike full MD simulations of both the solvent and the solute, in SEDMD the spatial structure of the solvent is ignored. The SEDMD algorithm is described in detail and applied to the study of the dynamics of a polymer chain tethered to a hard-wall subjected to uniform shear. SEDMD closely reproduces results obtained using traditional EDMD simulations with two orders of magnitude greater efficiency. Results question the existence of periodic (cycling) motion of the polymer chain.

  12. Vortex matter driven through mesoscopic channels

    NASA Astrophysics Data System (ADS)

    Kes, P. H.; Kokubo, N.; Besseling, R.

    2004-08-01

    The dynamics of vortex matter confined to mesoscopic channels has been investigated by means of mode locking experiments. When vortices are coherently driven through the potential provided by static vortices pinned in the channel edges, interference between the washboard frequency of the moving vortex lattice and the frequency of the superimposed rf-drive causes (Shapiro-like) steps in the dc- I- V curves. The position of the voltage steps uniquely determines the number of moving rows in each channel. It also shows how the frustration between row spacing and channel width behaves as a function of magnetic field. Maxima in flow stress (∼ Ic) occur at mismatch conditions. They are related to the traffic-jam-like flow impedance caused by the disorder in the edges. At higher fields, near the 2D-melting line Bm( T), the mode-locking interference characteristic for crystalline motion, strongly depends on the velocity, i.e. the applied frequency at which the vortex motion is probed. The minimum velocity at which coherent motion could be observed, diverges when the melting line is approached from below. Above the melting line interference is absent for any frequency. These observations give the first direct evidence for a dynamic phase transition of vortex matter driven through a disorder potential as predicted by Koshelev and Vinokur.

  13. Stimulus-driven and knowledge-driven processes in attention to warbles

    NASA Astrophysics Data System (ADS)

    Dowling, W. Jay; Tillmann, Barbara

    2003-10-01

    Listeners identified warbles differing in amplitude-modulation rate (3-10 Hz). And measured RT while listeners maintained above 90% correct responses. After a practice session listeners identified target warbles following stimulus-driven or knowledge-driven cues. The stimulus-driven cue was a 250-ms ``beep'' at the target pitch (valid) or another pitch (invalid); the knowledge-driven cue was a midrange ``melody'' pointing to the target pitch (always valid). A 500-ms target warble followed the cue after delays of 0-500 ms (250-750 ms SOA). The listener pressed a key to indicate ``slow'' or ``fast.'' RTs were shortest at the briefest delay. In contrast to results from a memory task, RTs here were much shorter, and we found no evidence for IOR or attentional blink. Listeners began generating responses while the target was still sounding. Invalid ``beeps'' slowed responses at the briefest (but not the longer) delays; adding a valid ``beep'' to the valid ``melody'' did not speed responses.

  14. ISOTROPICALLY DRIVEN VERSUS OUTFLOW DRIVEN TURBULENCE: OBSERVATIONAL CONSEQUENCES FOR MOLECULAR CLOUDS

    SciTech Connect

    Carroll, Jonathan J.; Frank, Adam; Blackman, Eric G.

    2010-10-10

    Feedback from protostellar outflows can influence the nature of turbulence in star-forming regions even if they are not the primary source of velocity dispersion for all scales of molecular clouds. For the rate and power expected in star-forming regions, we previously (Carroll et al.) demonstrated that outflows could drive supersonic turbulence at levels consistent with the scaling relations from Matzner although with a steeper velocity power spectrum than expected for an isotropically driven supersonic turbulent cascade. Here, we perform higher resolution simulations and combine simulations of outflow driven turbulence with those of isotropically forced turbulence. We find that the presence of outflows within an ambient isotropically driven turbulent environment produces a knee in the velocity power spectrum at the outflow scale and a steeper slope at sub-outflow scales than for a purely isotropically forced case. We also find that the presence of outflows flattens the density spectrum at large scales effectively reducing the formation of large-scale turbulent density structures. These effects are qualitatively independent of resolution. We have also carried out Principal Component Analysis (PCA) for synthetic data from our simulations. We find that PCA as a tool for identifying the driving scale of turbulence has a misleading bias toward low amplitude large-scale velocity structures even when they are not necessarily the dominant energy containing scales. This bias is absent for isotropically forced turbulence but manifests strongly for collimated outflow driven turbulence.

  15. The effects of goal-driven and data-driven regulation on metacognitive monitoring during learning: a developmental perspective.

    PubMed

    Koriat, Asher; Ackerman, Rakefet; Adiv, Shiri; Lockl, Kathrin; Schneider, Wolfgang

    2014-02-01

    Research in metacognition (Koriat, Ma'ayan, & Nussinson, 2006) suggests bidirectional links between monitoring and control during learning: When self-regulation is goal-driven, monitoring affects control so that increased study time (ST) enhances judgments of learning (JOLs). However, when self-regulation is data-driven, JOLs are based on the feedback from control, and therefore JOLs decrease with ST under the heuristic that ease of encoding is diagnostic of successful recall. Evidence for both types of relationships occurring within the same situation was found for adults. We examined the development of the ability to respond differentially to data-driven and goal-driven variation in ST within the same task. Children in Grades 5 and 6 exhibited a positive ST-JOL relationship for goal-driven regulation and a negative relationship for data-driven regulation but never in the same task. In contrast, the JOLs and recall of 9th graders and college students yielded differential cosensitivity to data-driven and goal-driven variation. The 5th and 6th graders also evidenced an adult-like pattern of JOLs and recall under a partitioning procedure that helped them in factoring the variation in ST due to data-driven and goal-driven variation in ST. The results are discussed in terms of the metacognitive sophistication needed for considering both types of variation simultaneously in making metacognitive judgments. PMID:23421442

  16. Influence of driven current on resistive tearing mode in Tokamaks

    NASA Astrophysics Data System (ADS)

    Wang, S.; Ma, Z. W.; Zhang, W.

    2016-05-01

    The influence of driven current on the m /n =2 /1 resistive tearing mode is studied systematically using a three-dimensional toroidal magnetohydrodynamic code. A uniform driven current with Gaussian distribution in the radial direction is imposed around the unperturbed rational surface. It is found that the driven current can locally modify the profiles of the current and safety factor, such that the tearing mode becomes linearly stable. The stabilizing effect increases with the increase of the driven current Icd or the decrease of its width δcd , unless an excessively large driven current reverses the magnetic shear near the rational surface and drives other instabilities such as double or triple tearing modes. The stabilizing effect can be negligible or becomes reversed if the maximum driven current density is not at the unperturbed rational surface.

  17. Solar Dynamo Driven by Periodic Flow Oscillation

    NASA Technical Reports Server (NTRS)

    Mayr, Hans G.; Hartle, Richard E.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    We have proposed that the periodicity of the solar magnetic cycle is determined by wave mean flow interactions analogous to those driving the Quasi Biennial Oscillation in the Earth's atmosphere. Upward propagating gravity waves would produce oscillating flows near the top of the radiation zone that in turn would drive a kinematic dynamo to generate the 22-year solar magnetic cycle. The dynamo we propose is built on a given time independent magnetic field B, which allows us to estimate the time dependent, oscillating components of the magnetic field, (Delta)B. The toroidal magnetic field (Delta)B(sub phi) is directly driven by zonal flow and is relatively large in the source region, (Delta)(sub phi)/B(sub Theta) much greater than 1. Consistent with observations, this field peaks at low latitudes and has opposite polarities in both hemispheres. The oscillating poloidal magnetic field component, (Delta)B(sub Theta), is driven by the meridional circulation, which is difficult to assess without a numerical model that properly accounts for the solar atmosphere dynamics. Scale-analysis suggests that (Delta)B(sub Theta) is small compared to B(sub Theta) in the dynamo region. Relative to B(sub Theta), however, the oscillating magnetic field perturbations are expected to be transported more rapidly upwards in the convection zone to the solar surface. As a result, (Delta)B(sub Theta) (and (Delta)B(sub phi)) should grow relative to B(sub Theta), so that the magnetic fields reverse at the surface as observed. Since the meridional and zonai flow oscillations are out of phase, the poloidal magnetic field peaks during times when the toroidal field reverses direction, which is observed. With the proposed wave driven flow oscillation, the magnitude of the oscillating poloidal magnetic field increases with the mean rotation rate of the fluid. This is consistent with the Bode-Blackett empirical scaling law, which reveals that in massive astrophysical bodies the magnetic moment tends

  18. Foam-Driven Fractures of an Elastic Matrix

    NASA Astrophysics Data System (ADS)

    Lai, Ching-Yao; Smiddy, Sam; Stone, Howard

    2015-11-01

    We report an experimental study of foam-driven fractures in an elastic matrix. When a pressurized foam is constantly injected into a gelatin matrix with a constant flow rate, the foam generates a disc-like fracture which is commonly observed in liquid-driven fractures. Compare to liquid-driven fractures, foam-driven fractures grow faster with time. We investigate how the rheological behaviour of foams affects the fracture characteristics by varying the air volume fraction of the foam, the types and concentration of surfactants in the foam. Foam-fracturing reduces the environmental costs of hydraulic fracturing, which inspires this laboratory study.

  19. Dynamical Critical Phenomena in Driven-Dissipative Systems

    NASA Astrophysics Data System (ADS)

    Sieberer, L. M.; Huber, S. D.; Altman, E.; Diehl, S.

    2013-05-01

    We explore the nature of the Bose condensation transition in driven open quantum systems, such as exciton-polariton condensates. Using a functional renormalization group approach formulated in the Keldysh framework, we characterize the dynamical critical behavior that governs decoherence and an effective thermalization of the low frequency dynamics. We identify a critical exponent special to the driven system, showing that it defines a new dynamical universality class. Hence critical points in driven systems lie beyond the standard classification of equilibrium dynamical phase transitions. We show how the new critical exponent can be probed in experiments with driven cold atomic systems and exciton-polariton condensates.

  20. Microscopic dynamics of synchronization in driven colloids

    PubMed Central

    Juniper, Michael P.N.; Straube, Arthur V.; Besseling, Rut; Aarts, Dirk G.A.L.; Dullens, Roel P.A.

    2015-01-01

    Synchronization of coupled oscillators has been scrutinized for over three centuries, from Huygens' pendulum clocks to physiological rhythms. One such synchronization phenomenon, dynamic mode locking, occurs when naturally oscillating processes are driven by an externally imposed modulation. Typically only averaged or integrated properties are accessible, leaving underlying mechanisms unseen. Here, we visualize the microscopic dynamics underlying mode locking in a colloidal model system, by using particle trajectories to produce phase portraits. Furthermore, we use this approach to examine the enhancement of mode locking in a flexible chain of magnetically coupled particles, which we ascribe to breathing modes caused by mode-locked density waves. Finally, we demonstrate that an emergent density wave in a static colloidal chain mode locks as a quasi-particle, with microscopic dynamics analogous to those seen for a single particle. Our results indicate that understanding the intricate link between emergent behaviour and microscopic dynamics is key to controlling synchronization. PMID:25994921

  1. Edge convection driven by externally applied potentials

    SciTech Connect

    D'Ippolito, D. A.; Myra, J. R.

    2000-08-01

    A theoretical model of convection in collisional tokamak edge and scrape-off-layer plasmas is described. In the linear theory, any mechanism for poloidal and toroidal symmetry breaking of the equilibrium will drive ExB flows; this result stems from the parallel thermal and pressure forces in Ohm's law. In the nonlinear theory, the quadratic coupling of the perturbations leads to quasilinear-type fluxes in the vorticity, density, and temperature equations. If the convection is strong enough, these fluxes lead to an ambipolarity constraint on the equilibrium electric field and to increased transport of particles and energy. The theory shows qualitative agreement with some tokamak experiments in which potential perturbations are externally driven by radio frequency antennas. (c) 2000 American Institute of Physics.

  2. Arc-driven rail gun research

    NASA Technical Reports Server (NTRS)

    Ray, P. K.

    1984-01-01

    The equations describing the performance of an inductively-driven rail gun are analyzed numerically. Friction between the projectile and rails is included through an empirical formulation. The equations are applied to the experiment of Rashleigh and Marshall to obtain an estimate of energy distribution in rail guns as a function of time. The effect of frictional heat dissipation on the bore of the gun is calculated. The mechanism of plasma and projectile acceleration in a dc rail gun is described from a microscopic point of view through the establishment of the Hall field. The plasma conductivity is shown to be a tensor indicating that there is a small component of current parallel to the direction of acceleration. The plasma characteristics are evaluated as a function of plasma mass through a simple fluid mechanical analysis of the plasma. By equating the energy dissipated in the plasma with the radiation heat loss, the properties of the plasma are determined.

  3. Bistability in a Driven-Dissipative Superfluid.

    PubMed

    Labouvie, Ralf; Santra, Bodhaditya; Heun, Simon; Ott, Herwig

    2016-06-10

    We experimentally study a driven-dissipative Josephson junction array, realized with a weakly interacting Bose-Einstein condensate residing in a one-dimensional optical lattice. Engineered losses on one site act as a local dissipative process, while tunneling from the neighboring sites constitutes the driving force. We characterize the emerging steady states of this atomtronic device. With increasing dissipation strength γ the system crosses from a superfluid state, characterized by a coherent Josephson current into the lossy site, to a resistive state, characterized by an incoherent hopping transport. For intermediate values of γ, the system exhibits bistability, where a superfluid and an incoherent branch coexist. We also study the relaxation dynamics towards the steady state, where we find a critical slowing down, indicating the presence of a nonequilibrium phase transition. PMID:27341243

  4. Saline and particle-driven interfacial intrusions

    NASA Astrophysics Data System (ADS)

    de Rooij, Frans; Linden, P. F.; Dalziel, Stuart B.

    1999-06-01

    This paper presents a theoretical and experimental investigation into saline and particle-driven intrusions along the interface between two layers of different densities. The conditions at the nose of an intrusion are described in an analysis similar to that applied by Benjamin (1968) to boundary gravity currents. Equations for propagation velocity and front position as functions of relative density are derived. These are used in an integral model for intrusions, which also includes the effects of sedimentation of particles and detrainment of interstitial fluid. The model describes the time-evolution of the length of the intrusion and the sediment distribution it produces. Laboratory experiments were carried out with lock-releases of a fixed volume of saline or particle-laden fluid into a two-layer stratification. Measurements were taken of the intrusion propagation, intrusion position and sediment distribution, and are found to be in good agreement with the solutions of the integral model.

  5. Bistability in a Driven-Dissipative Superfluid

    NASA Astrophysics Data System (ADS)

    Labouvie, Ralf; Santra, Bodhaditya; Heun, Simon; Ott, Herwig

    2016-06-01

    We experimentally study a driven-dissipative Josephson junction array, realized with a weakly interacting Bose-Einstein condensate residing in a one-dimensional optical lattice. Engineered losses on one site act as a local dissipative process, while tunneling from the neighboring sites constitutes the driving force. We characterize the emerging steady states of this atomtronic device. With increasing dissipation strength γ the system crosses from a superfluid state, characterized by a coherent Josephson current into the lossy site, to a resistive state, characterized by an incoherent hopping transport. For intermediate values of γ , the system exhibits bistability, where a superfluid and an incoherent branch coexist. We also study the relaxation dynamics towards the steady state, where we find a critical slowing down, indicating the presence of a nonequilibrium phase transition.

  6. Object-oriented model-driven control

    NASA Astrophysics Data System (ADS)

    Drysdale, A.; McRoberts, M.; Sager, J.; Wheeler, R.

    1994-11-01

    A monitoring and control subsystem architecture has been developed that capitalizes on the use of model-driven monitoring and predictive control, knowledge-based data representation, and artificial reasoning in an operator support mode. We have developed an object-oriented model of a Controlled Ecological Life Support System (CELSS). The model, based on the NASA Kennedy Space Center CELSS breadboard data, tracks carbon, hydrogen, and oxygen, carbon dioxide, and water. It estimates and tracks resource-related parameters such as mass, energy, and manpower measurements such as growing area required for balance. We are developing an interface with the breadboard systems that is compatible with artificial reasoning. Initial work is being done on use of expert systems and user interface development. This paper presents our approach to defining universally applicable CELSS monitor and control issues, and implementing appropriate monitor and control capability for a particular instance: the KSC CELSS Breadboard Facility.

  7. Periodically driven quantum ratchets: Symmetries and resonances

    SciTech Connect

    Denisov, S.; Haenggi, P.; Morales-Molina, L.; Flach, S.

    2007-06-15

    We study the quantum version of a tilting and flashing Hamiltonian ratchet, consisting of a periodic potential and a time-periodic driving field. The system dynamics is governed by a Floquet evolution matrix bearing the symmetry of the corresponding Hamiltonian. The dc-current appears due to the desymmetrization of Floquet eigenstates, which become transporting when all the relevant symmetries are violated. Those eigenstates that mostly contribute to a directed transport reside in phase space regions corresponding to classical resonances. Quantum dynamics leads to the dependence of the average velocity on the initial phase of the ac-field. A resonant enhancement (or suppression) of the dc-current, due to avoided crossings between different Floquet states, takes place upon tuning some control parameters. Our studies are predominantly aimed at experimental realizations of ac-driven quantum ratchets with cold atoms.

  8. Successful alliances driven by processes, not discounts

    SciTech Connect

    Brett, J.F.; Craig, V.B.; Pile, K.E.; Wadsworth, D.B.; Brett, K.V.; Aslakson, J.

    1996-09-23

    When alliances are executed properly and partners have a full understanding of true integration, drilling ventures can improve their potential to reduce costs and accelerate production by 12--30%. Many companies enter alliances without a full grasp of the economic potential such a relationship might offer. Many alliances rely too heavily on relationship issues and commercial terms instead of focusing on integrating their technical processes successfully. Process-driven alliance (PDA) is the term adopted by a new Gas Research Institute report prepared by OGCI Management Inc. to represent a fundamentally different way to plan, execute, and evaluate drilling projects. This paper discusses the findings of the GRI study, describing the stability of PDAs, value chain, successful PDAs, changed commercial terms, and characteristics of failure.

  9. Granular Segregation Driven by Particle Interactions

    NASA Astrophysics Data System (ADS)

    Lozano, C.; Zuriguel, I.; Garcimartín, A.; Mullin, T.

    2015-05-01

    We report the results of an experimental study of particle-particle interactions in a horizontally shaken granular layer that undergoes a second order phase transition from a binary gas to a segregation liquid as the packing fraction C is increased. By focusing on the behavior of individual particles, the effect of C is studied on (1) the process of cluster formation, (2) cluster dynamics, and (3) cluster destruction. The outcomes indicate that the segregation is driven by two mechanisms: attraction between particles with the same properties and random motion with a characteristic length that is inversely proportional to C . All clusters investigated are found to be transient and the probability distribution functions of the separation times display a power law tail, indicating that the splitting probability decreases with time.

  10. Granular segregation driven by particle interactions.

    PubMed

    Lozano, C; Zuriguel, I; Garcimartín, A; Mullin, T

    2015-05-01

    We report the results of an experimental study of particle-particle interactions in a horizontally shaken granular layer that undergoes a second order phase transition from a binary gas to a segregation liquid as the packing fraction C is increased. By focusing on the behavior of individual particles, the effect of C is studied on (1) the process of cluster formation, (2) cluster dynamics, and (3) cluster destruction. The outcomes indicate that the segregation is driven by two mechanisms: attraction between particles with the same properties and random motion with a characteristic length that is inversely proportional to C. All clusters investigated are found to be transient and the probability distribution functions of the separation times display a power law tail, indicating that the splitting probability decreases with time.

  11. Nuclear-driven solid-state lasers

    NASA Astrophysics Data System (ADS)

    Prelas, Mark A.

    A total system efficiency of 3 percent is calculated for very high average power active mirror solid-state laser amplifiers of co-doped material, such as Nd:Cr:GSGG, pumped by visible nuclear-driven alkali metal excimer fluorescence. The fluorescence is transported around a radiation shield, separating the fluorescer and the laser, by a large diameter-to-length ratio hollow lightpipe. Parameters for a system with peak power of 6 MW for 1 ms pulse at 1 Hz for an average power output of 6 kW are presented. This type of system would require the development of a small 200-kW thermal nuclear reactor (similar in size to small university research reactors). A much larger system can be developed as well.

  12. Test Driven Development of Scientific Models

    NASA Technical Reports Server (NTRS)

    Clune, Thomas L.

    2014-01-01

    Test-Driven Development (TDD), a software development process that promises many advantages for developer productivity and software reliability, has become widely accepted among professional software engineers. As the name suggests, TDD practitioners alternate between writing short automated tests and producing code that passes those tests. Although this overly simplified description will undoubtedly sound prohibitively burdensome to many uninitiated developers, the advent of powerful unit-testing frameworks greatly reduces the effort required to produce and routinely execute suites of tests. By testimony, many developers find TDD to be addicting after only a few days of exposure, and find it unthinkable to return to previous practices.After a brief overview of the TDD process and my experience in applying the methodology for development activities at Goddard, I will delve more deeply into some of the challenges that are posed by numerical and scientific software as well as tools and implementation approaches that should address those challenges.

  13. Accelerator Driven Nuclear Energy: The Thorium Option

    SciTech Connect

    Raja, Rajendran

    2009-03-18

    Conventional nuclear reactors use enriched Uranium as fuel and produce nuclear waste which needs to be stored away for over 10,000 years. At the current rate of use, existing sources of Uranium will last for 50-100 years. We describe a solution to the problem that uses particle accelerators to produce fast neutrons that can be used to burn existing nuclear waste and produce energy. Such systems, initially proposed by Carlo Rubbia and collaborators in the 1990's, are being seriously considered by many countries as a possible solution to the green energy problem. Accelerator driven reactors operate in a sub-critical regime and, thus, are safer and can obtain energy from plentiful elements such as Thorium-232 and Uranium-238. What is missing is the high intensity (10MW) accelerator that produces 1 GeV protons. We will describe scenarios which if implemented will make such systems a reality.

  14. Heat engine driven by purely quantum information.

    PubMed

    Park, Jung Jun; Kim, Kang-Hwan; Sagawa, Takahiro; Kim, Sang Wook

    2013-12-01

    The key question of this Letter is whether work can be extracted from a heat engine by using purely quantum mechanical information. If the answer is yes, what is its mathematical formula? First, by using a bipartite memory we show that the work extractable from a heat engine is bounded not only by the free energy change and the sum of the entropy change of an individual memory but also by the change of quantum mutual information contained inside the memory. We then find that the engine can be driven by purely quantum information, expressed as the so-called quantum discord, forming a part of the quantum mutual information. To confirm it, as a physical example we present the Szilard engine containing a diatomic molecule with a semipermeable wall.

  15. Arnold diffusion in a driven optical lattice.

    PubMed

    Boretz, Yingyue; Reichl, L E

    2016-03-01

    The effect of time-periodic forces on matter has been a topic of growing interest since the advent of lasers. It is known that dynamical systems with 2.5 or more degrees of freedom are intrinsically unstable. As a consequence, time-periodic driven systems can experience large excursions in energy. We analyze the classical and quantum dynamics of rubidium atoms confined to a time-periodic optical lattice with 2.5 degrees of freedom. When the laser polarizations are orthogonal, the system consists of two 1.5 uncoupled dynamical systems. When laser polarizations are turned away from orthogonal, an Arnold web forms and the dynamics undergoes a fundamental change. For parallel polarizations, we find huge random excursions in the rubidium atom energies and significant entanglement of energies in the quantum dynamics. PMID:27078351

  16. Shock Driven Twinning in Tantalum Single Crystals

    SciTech Connect

    McNaney, J M; HSUING, L M; Barton, N R; Kumar, M

    2009-07-20

    Recovery based observations of high pressure material behavior generated under high explosively driven flyer based loading conditions are reported. Two shock pressures, 25, and 55 GPa and four orientations {l_brace}(100), (110), (111), (123){r_brace} were considered. Recovered material was characterized using electron backscatter diffraction along with a limited amount of transmission electron microscopy to assess the occurrence of twinning under each test condition. Material recovered from 25 GPa had a very small fraction of twinning for the (100), (110), and (111) oriented crystals while a more noticeable fraction of the (123) oriented crystal was twinned. Material recovered from 55 GPa showed little twinning for (100) orientation slightly more for the (111) orientation and a large area fraction for the (123) orientation. The EBSD and TEM observations of the underlying deformation substructure are rationalized by comparing with previous static and dynamic results.

  17. Hopf bifurcation in the driven cavity

    NASA Technical Reports Server (NTRS)

    Goodrich, John W.; Gustafson, Karl; Halasi, Kadosa

    1989-01-01

    Incompressible two dimensional calculations are reported for the impulsively started lid driven cavity with aspect ratio two. The algorithm is based on the time dependent streamfunction equation, with a Crank-Nicolson differencing scheme for the diffusion terms, and with an Adams-Bashforth scheme for the convection terms. A multigrid method is used to solve the linear implicit equations at each time step. Periodic asymptotic solutions have been found for Re = 10000 and for Re = 5000. The Re = 5000 results are validated by grid refinement calculations. The solutions are shown to be precisely periodic, and care is taken to demonstrate that asymptotic states were reached. A discussion is included about the indicators that are used to show that an asymptotic state was reached, and to show that the asymptotic state is indeed periodic.

  18. Datasheet Driven Silicon Carbide Power MOSFET Model

    SciTech Connect

    Mudholkar, M; Ahmed, S; Ericson, MN; Frank, SS; Britton, CL; Mantooth, HA

    2014-05-01

    A compact model for SiC Power MOSFETs is presented. The model features a physical description of the channel current and internal capacitances and has been validated for dc, CV, and switching characteristics with measured data from a 1200-V, 20-A SiC power MOSFET in a temperature range of 25 degrees C to 225 degrees C. The peculiar variation of on-state resistance with temperature for SiC power MOSFETs has also been demonstrated through measurements and accounted for in the developed model. In order to improve the user experience with the model, a new datasheet driven parameter extraction strategy has been presented which requires only data available in device datasheets, to enable quick parameter extraction for off-the-shelf devices. Excellent agreement is shown between measurement and simulation using the presented model over the entire temperature range.

  19. Instability in electromagnetically driven flows. I

    NASA Astrophysics Data System (ADS)

    Gissinger, Christophe; Rodriguez Imazio, Paola; Fauve, Stephan

    2016-03-01

    The magnetohydrodynamic flow driven by a travelling magnetic field in an annular channel is investigated numerically. For sufficiently large magnetic Reynolds number Rm, or if a large enough pressure gradient is externally applied, the system undergoes an instability in which the flow rate in the channel dramatically drops from synchronism with the wave to much smaller velocities. This transition takes the form of a saddle-node bifurcation for the time-averaged quantities. In this first paper, we characterize the bifurcation and study the stability of the flow as a function of several parameters. We show that the bifurcation of the flow involves a bistability between Poiseuille-like and Hartman-like regimes and relies on magnetic flux expulsion. Based on this observation, new predictions are made for the occurrence of this stalling instability.

  20. Turbulence driven particle transport in Texas Helimak

    NASA Astrophysics Data System (ADS)

    Toufen, D. L.; Guimarães-Filho, Z. O.; Caldas, I. L.; Marcus, F. A.; Gentle, K. W.

    2012-01-01

    We analyze the turbulence driven particle transport in Texas Helimak [K. W. Gentle and H. He, Plasma Sci. Technol. 10, 284 (2008)], a toroidal plasma device with a one-dimensional equilibrium with magnetic curvature and shear. Alterations on the radial electric field, through an external voltage bias, change the spectral plasma characteristics inducing a dominant frequency for negative bias values and a broad band frequency spectrum for positive bias values. When applying a negative bias, the transport is high where the waves propagate with phase velocities near the plasma flow velocity, an indication that the transport is strongly affected by a wave particle resonant interaction. On the other hand, for positive bias values, the plasma has a reversed shear flow, and we observe that the transport is almost zero in the shearless radial region, an evidence of a transport barrier in this region.

  1. Turbulence driven particle transport in Texas Helimak

    SciTech Connect

    Toufen, D. L.; Guimaraes-Filho, Z. O.; Marcus, F. A.; Caldas, I. L.; Gentle, K. W.

    2012-01-15

    We analyze the turbulence driven particle transport in Texas Helimak [K. W. Gentle and H. He, Plasma Sci. Technol. 10, 284 (2008)], a toroidal plasma device with a one-dimensional equilibrium with magnetic curvature and shear. Alterations on the radial electric field, through an external voltage bias, change the spectral plasma characteristics inducing a dominant frequency for negative bias values and a broad band frequency spectrum for positive bias values. When applying a negative bias, the transport is high where the waves propagate with phase velocities near the plasma flow velocity, an indication that the transport is strongly affected by a wave particle resonant interaction. On the other hand, for positive bias values, the plasma has a reversed shear flow, and we observe that the transport is almost zero in the shearless radial region, an evidence of a transport barrier in this region.

  2. Stop motion microphotography of laser driven plates

    SciTech Connect

    Frank, A.M.; Trott, W.M.

    1994-09-01

    Laser driven plates have been used for several years for high velocity shock wave and impact studies. Recent questions about the integrity and ablation rates of these plates coupled with an improved capability for microscopic stop motion photography led to this study. For these experiments, the plates were aluminum, coated on the ends of optical fibers. A high power laser pulse in the fiber ionizes the aluminum at the fiber/coating interface. The plasma thus created accelerates the remaining aluminum to high velocities, several kilometers per second. We defined {open_quotes}thick{close_quotes} or {open_quotes}thin{close_quotes} coatings as those where a flying plate (flyer) was launched vs. the material being completely ionized. Here we were specifically interested in the thick/thin boundary to develop data for the numerical models attempting to predict flyer behavior.

  3. Instability in electromagnetically driven flows. II

    NASA Astrophysics Data System (ADS)

    Rodriguez Imazio, Paola; Gissinger, Christophe

    2016-03-01

    In a previous paper, we have reported numerical simulations of the magnetohydrodynamic flow driven by a travelling magnetic field in an annular channel, at low Reynolds number. It was shown that the stalling of such induction pump is strongly related to magnetic flux expulsion. In the present article, we show that for larger hydrodynamic Reynolds number, and with more realistic boundary conditions, this instability takes the form of a large axisymmetric vortex flow in the (r, z)-plane, in which the fluid is locally pumped in the direction opposite to the one of the magnetic field. Close to the marginal stability of this vortex flow, a low-frequency pulsation is generated. Finally, these results are compared to theoretical predictions and are discussed within the framework of experimental annular linear induction electromagnetic pumps.

  4. Laser-Driven Mini-Thrusters

    SciTech Connect

    Sterling, Enrique; Lin Jun; Sinko, John; Kodgis, Lisa; Porter, Simon; Pakhomov, Andrew V.; Larson, C. William; Mead, Franklin B. Jr.

    2006-05-02

    Laser-driven mini-thrusters were studied using Delrin registered and PVC (Delrin registered is a registered trademark of DuPont) as propellants. TEA CO2 laser ({lambda} = 10.6 {mu}m) was used as a driving laser. Coupling coefficients were deduced from two independent techniques: force-time curves measured with a piezoelectric sensor and ballistic pendulum. Time-resolved ICCD images of the expanding plasma and combustion products were analyzed in order to determine the main process that generates the thrust. The measurements were also performed in a nitrogen atmosphere in order to test the combustion effects on thrust. A pinhole transmission experiment was performed for the study of the cut-off time when the ablation/air breakdown plasma becomes opaque to the incoming laser pulse.

  5. Value-driven attentional capture in adolescence.

    PubMed

    Roper, Zachary J J; Vecera, Shaun P; Vaidya, Jatin G

    2014-11-01

    Adolescence has been characterized as a period of both opportunity and vulnerability. Numerous clinical conditions, including substance-use disorders, often emerge during adolescence. These maladaptive behaviors have been linked to problems with cognitive control, yet few studies have investigated how rewards differentially modulate attentional processes in adolescents versus adults. Here, we trained adults and adolescents on a visual task to establish stimulus-reward associations. Later, we assessed learning in an extinction task in which previously rewarded stimuli periodically appeared as distractors. Both age groups initially demonstrated value-driven attentional capture; however, the effect persisted longer in adolescents than in adults. The results could not be explained by developmental differences in visual working memory. Given the importance of attentional control to daily behaviors and clinical conditions such as attention-deficit/hyperactivity disorder, these results reveal that cognitive control failures in adolescence may be linked to a value-based attentional-capture effect. PMID:25210012

  6. Correlations and thermalization in driven cavity arrays

    SciTech Connect

    Dai Li; Angelakis, Dimitris G.; Kwek, Leong Chuan; Mancini, S.

    2011-09-23

    We show that long-distance steady-state quantum correlations (entanglement) between pairs of cavity-atom systems in an array of lossy and driven coupled resonators can be established and controlled. The maximal of entanglement for any pair is achieved when their corresponding direct coupling is much smaller than their individual couplings to the third party. This effect is reminiscent of the coherent trapping of the three-level atoms using two classical coherent fields. Different geometries for coherent control are considered. For finite temperature, the steady state of the coupled lossy atomcavity arrays with driving fields is in general not a thermal state. Using an appropriate distance measure for quantum states, we find that the change rate of the degree of thermalization with respect to the driving strength is consistent with the entanglement of the system.

  7. Photon scattering from strongly driven atomic ensembles

    SciTech Connect

    Jin Luling; Evers, Joerg; Macovei, Mihai

    2011-10-15

    The second-order correlation function for light emitted from a strongly and near-resonantly driven dilute cloud of atoms is discussed. Because of the strong driving, the fluorescence spectrum separates into distinct peaks, for which the spectral properties can be defined individually. It is shown that the second-order correlations for various combinations of photons from different spectral lines exhibit bunching together with super-Poissonian or sub-Poissonian photon statistics, tunable by the choice of the detector positions. Additionally, a Cauchy-Schwarz inequality is violated for photons emitted from particular spectral bands. The emitted light intensity is proportional to the square of the number of particles, and thus can potentially be intense. Three different averaging procedures to model ensemble disorder are compared.

  8. Mission Success Driven Space System Sparing Analysis

    NASA Technical Reports Server (NTRS)

    Knezevic, J.

    1995-01-01

    Among the maintenance resources, the spare parts are the most difficult to predict. Items in the space systems are very different from the point of view of reliability, cost, weight, volume, etc. The different combinations of spares make different contribution to the: mission success, spare investment, volume occupied and weight. Hence, the selection of spares for a mission planned must take into account all of these features. This paper presents the generic mission success driven sparing model developed, for the complex space systems. The mathematical analysis used in the model enables the user to select the most suitable selection of the spare package for the mission planned. The illustrative examples presented clearly demonstrate the applicability and usefulness of the model introduced.

  9. Modeling of an Implosion Driven Hypervelocity Launcher

    NASA Astrophysics Data System (ADS)

    Loiseau, Jason; Higgins, Andrew; Szirti, Daniel; Batchelor, Patrick; Zhang, Fan; Tanguay, Vincent

    2007-06-01

    Modelling work carried out on the implosion driven launcher under concurrent development is presented. The launcher consists of a thin walled metal tube surrounded by explosive which when detonated pinches the tube shut and drives a strong shock into the projectile. The commercial hydrocode LS-DYNA was used to quantitatively and qualitatively evaluate the design parameters of the launcher and their effect on implosion dynamics and performance. These parameters include fill pressure, tube diameter, explosive layer thickness, and explosives tampering. The launcher is primarily modeled using a quasi 2D Arbitrary Langrage Euler formulation. A full 3-D axisymmetric model is also employed. The model is evaluated against experimental data previously collected. Additional developmental work on a second stage launcher taking advantage of a phase velocity between the imploding tube and explosives via the use of angled flyer plates and cones is also carried out.

  10. Earthquake-Driven Erosion and Mountain Building

    NASA Astrophysics Data System (ADS)

    Li, G.; West, A. J.

    2015-12-01

    Earthquake-triggered landslides are thought to play a major role in the erosion budget of mountainous topography in tectonically active regions, but the long-term topographic effects of seismically-driven denudation over multiple seismic cycles remain to be fully explored. In this work, we focus on the Longmen Shan range along the eastern edge of the Tibetan Plateau, where the 2008 Mw 7.9 Wenchuan earthquake triggered tens of thousands of landslides. We assess regional erosion rates from decadal to millennial to Myr timescales, using pre-Wenchuan and post-Wenchuan hydrological gauging data, cosmogenic ages, and thermal cooling rates, respectively. We use these data to evaluate the magnitude and proportion of erosion associated with the Wenchuan event, and we then use this case study along with earthquake Mw-frequency relations to consider earthquake-driven erosion over multiple earthquake cycles. We find that, as long as rivers are capable of removing landslide debris within the timescale of earthquake return times, focused denudation along an orogenic margin such as the eastern edge of the Tibetan plateau can be explained by repeated earthquake events, without explicit need for a strong climatic driver of focused erosion. We develop a generalized 2-D model that accounts for both seismically-induced denudation and uplift (co-seismic uplift, visco-elastic relaxation and flexural-isostatic responses). This model can explain, through repeated seismic events, the development and maintenance of high topography as seen along the eastern Tibetan plateau. We consider the implications of this model for simulating mountain growth in various tectonic settings, contributing to better understanding of the role of earthquakes in mountain building.

  11. A data-driven acute inflammation therapy

    PubMed Central

    2013-01-01

    Acute inflammation is a severe medical condition defined as an inflammatory response of the body to an infection. Its rapid progression requires quick and accurate decisions from clinicians. Inadequate and delayed decisions makes acute inflammation the 10th leading cause of death overall in United States with the estimated cost of treatment about $17 billion annually. However, despite the need, there are limited number of methods that could assist clinicians to determine optimal therapies for acute inflammation. We developed a data-driven method for suggesting optimal therapy by using machine learning model that is learned on historical patients' behaviors. To reduce both the risk of failure and the expense for clinical trials, our method is evaluated on a virtual patients generated by a mathematical model that emulates inflammatory response. In conducted experiments, acute inflammation was handled with two complimentary pro- and anti-inflammatory medications which adequate timing and doses are crucial for the successful outcome. Our experiments show that the dosage regimen assigned with our data-driven method significantly improves the percentage of healthy patients when compared to results by other methods used in clinical practice and found in literature. Our method saved 88% of patients that would otherwise die within a week, while the best method found in literature saved only 73% of patients. At the same time, our method used lower doses of medications than alternatives. In addition, our method achieved better results than alternatives when only incomplete or noisy measurements were available over time as well as it was less affected by therapy delay. The presented results provide strong evidence that models from the artificial intelligence community have a potential for development of personalized treatment strategies for acute inflammation. PMID:24565439

  12. Solvent driven motion of lithographically fabricated gels.

    PubMed

    Bassik, Noy; Abebe, Beza T; Gracias, David H

    2008-11-01

    We investigated the solvent driven motion of lithographically structured poly- N-isopropylacrylamide (PNIPAm) gels. The gels were soaked in ethanol and then transferred to water, where they moved spontaneously. This movement was driven by the expulsion of the ethanol from the gel and subsequent ethanol spreading at the air-water interface. We utilized lithographic patterning of the gels at the micron-millimeter length scales to investigate the effect of size, shape and symmetry. Lithographic patterning allowed the structures to be fabricated in an identical manner, thereby allowing a single variable (such as shape, size, or symmetry) to be altered while minimizing change in other variables such as thickness, roughness and swelling characteristics. The diverse range of motions including translation, precession and rotation could be controlled and were recorded using videography. Gels were lithographically patterned with features less than 100 microm, and exhibited remarkably high linear and rotational velocities of up to 31 cm/s and 3529 rpm over time spans of seconds to minutes. We observed a reciprocal dependence of maximum rotational velocity on linear dimension. The linear velocity for all types of motion, along a line or curve, was analyzed and found to be similar across different shapes and sizes. This velocity was in the range of 17-39 cm/s even though our sizes and shapes varied across orders of magnitude. We postulate that this velocity is related to the velocity of spreading of ethanol on water, which is approximately 53 cm/s. Additionally, since this solvent powered motion is a clean, quiet and reusable source of motive power, with no need for on-board wiring or batteries, we explored applications in moving lithographically integrated metallic payloads on top of the gels and utilized the gels to move larger floating objects.

  13. Integrated Nucleosynthesis in Neutrino Driven Winds

    SciTech Connect

    Roberts, L F; Woosley, S E; Hoffman, R D

    2010-03-26

    Although they are but a small fraction of the mass ejected in core-collapse supernovae, neutrino-driven winds (NDWs) from nascent proto-neutron stars (PNSs) have the potential to contribute significantly to supernova nucleosynthesis. In previous works, the NDW has been implicated as a possible source of r-process and light p-process isotopes. In this paper we present time-dependent hydrodynamic calculations of nucleosynthesis in the NDW which include accurate weak interaction physics coupled to a full nuclear reaction network. Using two published models of PNS neutrino luminosities, we predict the contribution of the NDW to the integrated nucleosynthetic yield of the entire supernova. For the neutrino luminosity histories considered, no true r-process occurs in the most basic scenario. The wind driven from an older 1.4M{sub {circle_dot}} model for a PNS is moderately neutron-rich at late times however, and produces {sup 87}Rb, {sup 88}Sr, {sup 89}Y, and {sup 90}Zr in near solar proportions relative to oxygen. The wind from a more recently studied 1.27M{sub {circle_dot}} PNS is proton-rich throughout its entire evolution and does not contribute significantly to the abundance of any element. It thus seems very unlikely that the simplest model of the NDW can produce the r-process. At most, it contributes to the production of the N = 50 closed shell elements and some light p-nuclei. In doing so, it may have left a distinctive signature on the abundances in metal poor stars, but the results are sensitive to both uncertain models for the explosion and the masses of the neutron stars involved.

  14. Scaling up nanoscale water-driven energy conversion into evaporation-driven engines and generators

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Goodnight, Davis; Gao, Zhenghan; Cavusoglu, Ahmet H.; Sabharwal, Nina; Delay, Michael; Driks, Adam; Sahin, Ozgur

    2015-06-01

    Evaporation is a ubiquitous phenomenon in the natural environment and a dominant form of energy transfer in the Earth's climate. Engineered systems rarely, if ever, use evaporation as a source of energy, despite myriad examples of such adaptations in the biological world. Here, we report evaporation-driven engines that can power common tasks like locomotion and electricity generation. These engines start and run autonomously when placed at air-water interfaces. They generate rotary and piston-like linear motion using specially designed, biologically based artificial muscles responsive to moisture fluctuations. Using these engines, we demonstrate an electricity generator that rests on water while harvesting its evaporation to power a light source, and a miniature car (weighing 0.1 kg) that moves forward as the water in the car evaporates. Evaporation-driven engines may find applications in powering robotic systems, sensors, devices and machinery that function in the natural environment.

  15. Scaling up nanoscale water-driven energy conversion into evaporation-driven engines and generators

    PubMed Central

    Chen, Xi; Goodnight, Davis; Gao, Zhenghan; Cavusoglu, Ahmet H.; Sabharwal, Nina; DeLay, Michael; Driks, Adam; Sahin, Ozgur

    2015-01-01

    Evaporation is a ubiquitous phenomenon in the natural environment and a dominant form of energy transfer in the Earth's climate. Engineered systems rarely, if ever, use evaporation as a source of energy, despite myriad examples of such adaptations in the biological world. Here, we report evaporation-driven engines that can power common tasks like locomotion and electricity generation. These engines start and run autonomously when placed at air–water interfaces. They generate rotary and piston-like linear motion using specially designed, biologically based artificial muscles responsive to moisture fluctuations. Using these engines, we demonstrate an electricity generator that rests on water while harvesting its evaporation to power a light source, and a miniature car (weighing 0.1 kg) that moves forward as the water in the car evaporates. Evaporation-driven engines may find applications in powering robotic systems, sensors, devices and machinery that function in the natural environment. PMID:26079632

  16. Comparison of gate driven and source driven FET structures as THz detectors

    NASA Astrophysics Data System (ADS)

    Ali, Muhammad; Perenzoni, Matteo

    2014-05-01

    A 600 GHz Field Effect Transistor (FET) is implemented in 0.18 um CMOS technology as a THz detector for imaging applications. A total of 4 FET test structures were fabricated and measured for comparison purposes. Each structure is accompanied by an on-chip bow-tie antenna that directly feeds the detector with THz signal. The detectors are characterized by a THz source and a lock-in amplifier at a sensitivity of 100uV. Measurement results indicate the potential of using both these FET configurations as THz detectors in imaging applications. A normalized frequency sweep analysis shows the broadband nature of Source Driven (SD) FET over the Gate Driven (GD) counterpart. However, the GD structures are more responsive than SD structures. The measurement results also indicate that FET structures with smaller widths show higher voltage response than those with smaller widths for a given channel length.

  17. Family ethnic socialization and ethnic identity: a family-driven, youth-driven, or reciprocal process?

    PubMed

    Umaña-Taylor, Adriana J; Zeiders, Katharine H; Updegraff, Kimberly A

    2013-02-01

    The current study examined the longitudinal associations between family ethnic socialization and youths' ethnic identity among a sample of Mexican-origin youth (N = 178, Mage = 18.17, SD = .46). Findings from multiple-group cross lagged panel models over a 2-year period indicated that for U.S.-born youth with immigrant parents, the process appeared to be family driven: Youths' perceptions of family ethnic socialization in late adolescence were associated with significantly greater ethnic identity exploration and resolution in emerging adulthood, while youths' ethnic identity during late adolescence did not significantly predict youths' future perceptions of family ethnic socialization. Conversely, for U.S.-born youth with U.S. born parents, youths' ethnic identity significantly predicted their future perceptions of family ethnic socialization but perceptions of family ethnic socialization did not predict future levels of youths' ethnic identity, suggesting a youth-driven process. Findings were consistent for males and females.

  18. Differentiating between marketing-driven and technology-driven vendors of medical information systems.

    PubMed

    Friedman, B A; Mitchell, W; Singh, K

    1994-08-01

    Buyers of medical information systems such as laboratory information systems need to recognize that the vendors of such systems may pursue corporate strategies emphasizing expenditures on marketing and client services, expenditures on technology and research and development (R&D), or a more balanced approach. The strategic goals and objectives of a vendor of an information system should align closely with those of a potential hospital client. A restless hospital client seeking cutting-edge technology will probably be dissatisfied with a system vendor who emphasizes slow ongoing incremental system development. Objective criteria for distinguishing between a marketing-driven vendor and a technology-driven vendor of medical information systems, and their variants, are presented based on the ratio of marketing expenditures to sales revenue compared with the ratio of research and development expenditures to sales revenue of the company. More subjective narrative criteria are also offered for making such distinctions. PMID:8060224

  19. Scaling up nanoscale water-driven energy conversion into evaporation-driven engines and generators.

    PubMed

    Chen, Xi; Goodnight, Davis; Gao, Zhenghan; Cavusoglu, Ahmet H; Sabharwal, Nina; DeLay, Michael; Driks, Adam; Sahin, Ozgur

    2015-06-16

    Evaporation is a ubiquitous phenomenon in the natural environment and a dominant form of energy transfer in the Earth's climate. Engineered systems rarely, if ever, use evaporation as a source of energy, despite myriad examples of such adaptations in the biological world. Here, we report evaporation-driven engines that can power common tasks like locomotion and electricity generation. These engines start and run autonomously when placed at air-water interfaces. They generate rotary and piston-like linear motion using specially designed, biologically based artificial muscles responsive to moisture fluctuations. Using these engines, we demonstrate an electricity generator that rests on water while harvesting its evaporation to power a light source, and a miniature car (weighing 0.1 kg) that moves forward as the water in the car evaporates. Evaporation-driven engines may find applications in powering robotic systems, sensors, devices and machinery that function in the natural environment.

  20. A comparison of wake measurements in motor-driven and flow-driven turbine experiments

    NASA Astrophysics Data System (ADS)

    Araya, Daniel B.; Dabiri, John O.

    2015-07-01

    We present experimental data to compare and contrast the wake characteristics of a turbine whose rotation is either driven by the oncoming flow or prescribed by a motor. Velocity measurements are collected using two-dimensional particle image velocimetry in the near-wake region of a lift-based, vertical-axis turbine. The wake of this turbine is characterized by a spanwise asymmetric velocity profile which is found to be strongly dependent on the turbine tip speed ratio (TSR), while only weakly dependent on Reynolds number ( Re). For a given Re, the TSR is controlled either passively by a mechanical brake or actively by a DC motor. We find that there exists a finite region in TSR versus Re space where the wakes of the motor-driven turbine and flow-driven turbine are indistinguishable to within experimental precision. Outside of this region, the sign of the net circulation in the wake changes as TSR is increased by the motor. Shaft torque measurements show a corresponding sign change above this TSR threshold set by circulation, indicating a transition from net torque due to lift to net torque due to drag produced by the turbine blades, the latter of which can give wake measurements that are inconsistent with a flow-driven turbine. The results support the claim that the turbine kinematics and aerodynamic properties are the sole factors that govern the dynamics of its wake, irrespective of the means to move the turbine blades. This has significance for both experimental and computational studies where it may be necessary, or perhaps more economical, to prescribe the turbine kinematics in order to analyze its aerodynamic characteristics.

  1. A photochemically driven molecular-level abacus

    PubMed

    Ashton; Ballardini; Balzani; Credi; Dress; Ishow; Kleverlaan; Kocian; Preece; Spencer; Stoddart; Venturi; Wenger

    2000-10-01

    A molecular-level abacus-like system driven by light inputs has been designed in the form of a [2]rotaxane, comprising the pi-electron-donating macrocyclic polyether bis-p-phenylene-34-crown-10 (BPP34C10) and a dumbbell-shaped component that contains 1) a Ru(II) polypyridine complex as one of its stoppers in the form of a photoactive unit, 2) a p-terphenyl-type ring system as a rigid spacer, 3) a 4,4'-bipyridinium unit and a 3,3'-dimethyl-4,4'-bipyridinium unit as pi-electron-accepting stations, and 4) a tetraarylmethane group as the second stopper. The synthesis of the [2]rotaxane was accomplished in four successive stages. First of all, the dumbbell-shaped component of the [2]rotaxane was constructed by using conventional synthetic methodology to make 1) the so-called "west-side" comprised of the Ru(II) polypyridine complex linked by a bismethylene spacer to the p-terphenyl-type ring system terminated by a benzylic bromomethyl function and 2) the so-called "east-side" comprised of the tetraarylmethane group, attached by a polyether linkage to the bipyridinium unit, itself joined in turn by a trismethylene spacer to an incipient 3,3'-dimethyl-4,4'-bipyridinium unit. Next, 3) the "west-side" and "east-side" were fused together by means of an alkylation to give the dumbbell-shaped compound, which was 4) finally subjected to a thermodynamically driven slippage reaction, with BPP34C10 as the ring, to afford the [2]rotaxane. The structure of this interlocked molecular compound was characterized by mass spectrometry and NMR spectroscopy, which also established, along with cyclic voltammetry, the co-conformational behavior of the molecular shuttle. The stable translational isomer is the one in which the BPP34C10 component encircles the 4,4'-bipyridinium unit, in keeping with the fact that this station is a better pi-electron acceptor than the other station. This observation raises the question- can the BPP34C10 macrocycle be made to shuttle between the two stations by a

  2. Radiation-Driven Warping. 2; Nonisothermal Disks

    NASA Technical Reports Server (NTRS)

    Maloney, Philip R.; Begelman, Mitchell C.; Nowak, Michael A.

    1998-01-01

    Recent work by Pringle and by Maloney, Begelman, & Pringle has shown that geometrically thin, optically thick, accretion disks are unstable to warping driven by radiation torque from the central source. This work was confined to isothermal (i.e., surface density Sigma varies as R(sup -3/2) disks. In this paper we generalize the study of radiation-driven warping to include general power-law surface density distributions, Sigma varies as R(sup -delta).We consider the range from Delta = 3/2 (the isothermal case) to Delta = -3/2, which corresponds to a radiation-pressure-supported disk; this spans the range of surface density distributions likely to be found in real astrophysical disks. In all cases there are an infinite number of zero-crossing solutions (i.e., solutions that cross the equator), which are the physically relevant modes if the outer boundary of the disk is required to lie in a specified plane. However, unlike the isothermal disk, which is the degenerate case, the frequency eigenvalues for Delta does not equal 3/2 are all distinct. In all cases the location of the zero moves outward from the steady state (pure precession) value with increasing growth rate; thus, there is a critical minimum size for unstable disks. Modes with zeros at smaller radii are damped. The critical radius and the steady state precession rate depend only weakly on Delta. An additional analytic solution has been found for Delta = 1. The case Delta = 1 divides the solutions into two qualitatively different regimes. For Delta greater than or equal to 1, the fastest growing modes have maximum warp amplitude, close to the disk outer edge, and the ratio of Beta(sub max) to the warp amplitude at the disk inner edge, Beta(sub o), is much greater than 1. For Delta less than 1, Beta(sub max/Beta(sub o) approximately equals 1, and the warp maximum steadily approaches the origin as Delta decreases. This implies that nonlinear effects must be important if the warp extends to the disk inner edge

  3. The Myths that Drive Data-Driven Schools

    ERIC Educational Resources Information Center

    Jones, Alan

    2006-01-01

    In this article, the author discusses the most recent attempt by educators to emulate the "sound principles" and methods of business and science, which is to become data-driven. The leaders in a data-driven school are able to demonstrate how some number, preferably scores on standardized tests, moved up as a result of some program they initiated.…

  4. Object-Driven and Temporal Action Rules Mining

    ERIC Educational Resources Information Center

    Hajja, Ayman

    2013-01-01

    In this thesis, I present my complete research work in the field of action rules, more precisely object-driven and temporal action rules. The drive behind the introduction of object-driven and temporally based action rules is to bring forth an adapted approach to extract action rules from a subclass of systems that have a specific nature, in which…

  5. A Consumer-Driven Approach To Increase Suggestive Selling.

    ERIC Educational Resources Information Center

    Rohn, Don; Austin, John; Sanford, Alison

    2003-01-01

    Discussion of the effectiveness of behavioral interventions in improving suggestive selling behavior of sales staff focuses on a study that examined the efficacy of a consumer-driven approach to improve suggestive selling behavior of three employees of a fast food franchise. Reports that consumer-driven intervention increased suggestive selling…

  6. Instrumentation: Software-Driven Instrumentation: The New Wave.

    ERIC Educational Resources Information Center

    Salit, M. L.; Parsons, M. L.

    1985-01-01

    Software-driven instrumentation makes measurements that demand a computer as an integral part of either control, data acquisition, or data reduction. The structure of such instrumentation, hardware requirements, and software requirements are discussed. Examples of software-driven instrumentation (such as wavelength-modulated continuum source…

  7. A Framework for Goal-Driven Pair Drills

    ERIC Educational Resources Information Center

    Saito, Hidetoshi

    2008-01-01

    This paper proposes a framework for goal-driven pair drills. What distinguishes these drills from ordinary controlled drills lies in the motivating characteristics such as clear goals, outcomes, and communicativeness. With these features present, goal-driven pair drills encourage learners to process multiple layers of language skill aspects. A…

  8. Data-Driven Hint Generation from Peer Debugging Solutions

    ERIC Educational Resources Information Center

    Liu, Zhongxiu

    2015-01-01

    Data-driven methods have been a successful approach to generating hints for programming problems. However, the majority of previous studies are focused on procedural hints that aim at moving students to the next closest state to the solution. In this paper, I propose a data-driven method to generate remedy hints for BOTS, a game that teaches…

  9. Educational Accountability: A Qualitatively Driven Mixed-Methods Approach

    ERIC Educational Resources Information Center

    Hall, Jori N.; Ryan, Katherine E.

    2011-01-01

    This article discusses the importance of mixed-methods research, in particular the value of qualitatively driven mixed-methods research for quantitatively driven domains like educational accountability. The article demonstrates the merits of qualitative thinking by describing a mixed-methods study that focuses on a middle school's system of…

  10. The Dynamics of a Parametrically Driven Damped Pendulum

    NASA Astrophysics Data System (ADS)

    Das, A.; Kumar, K.

    2015-05-01

    Ordered and chaotic states of a parametrically driven planar pendulum with viscous damping are numerically investigated. The damping makes the number of chaotic windows fewer but with larger width. Stroboscopic maps of the chaotic motion of the pendulum, driven either subharmonically or harmonically, show strange attractors with inversion symmetry in the phase plane.

  11. Fokker-Planck/Transport model for neutral beam driven tokamaks

    SciTech Connect

    Killeen, J.; Mirin, A.A.; McCoy, M.G.

    1980-01-01

    The application of nonlinear Fokker-Planck models to the study of beam-driven plasmas is briefly reviewed. This evolution of models has led to a Fokker-Planck/Transport (FPT) model for neutral-beam-driven Tokamaks, which is described in detail. The FPT code has been applied to the PLT, PDX, and TFTR Tokamaks, and some representative results are presented.

  12. Overview of nonlinear theory of kinetically driven instabilities

    SciTech Connect

    Berk, H.L.; Breizman, B.N.

    1998-09-01

    An overview is presented of the theory for the nonlinear behavior of instabilities driven by the resonant wave particle interaction. The approach should be applicable to a wide variety of kinetic systems in magnetic fusion devices and accelerators. Here the authors emphasize application to Alfven were driven instability, and the principles of the theory are used to interpret experimental data.

  13. Accelerator-driven Transmutation of Waste

    NASA Astrophysics Data System (ADS)

    Venneri, Francesco

    1998-04-01

    Nuclear waste from commercial power plants contains large quantities of plutonium, other fissionable actinides, and long-lived fission products that are potential proliferation concerns and create challenges for the long-term storage. Different strategies for dealing with nuclear waste are being followed by various countries because of their geologic situations and their views on nuclear energy, reprocessing and non-proliferation. The current United States policy is to store unprocessed spent reactor fuel in a geologic repository. Other countries are opting for treatment of nuclear waste, including partial utilization of the fissile material contained in the spent fuel, prior to geologic storage. Long-term uncertainties are hampering the acceptability and eventual licensing of a geologic repository for nuclear spent fuel in the US, and driving up its cost. The greatest concerns are with the potential for radiation release and exposure from the spent fuel for tens of thousands of years and the possible diversion and use of the actinides contained in the waste for weapons construction. Taking advantage of the recent breakthroughs in accelerator technology and of the natural flexibility of subcritical systems, the Accelerator-driven Transmutation of Waste (ATW) concept offers the United States and other countries the possibility to greatly reduce plutonium, higher actinides and environmentally hazardous fission products from the waste stream destined for permanent storage. ATW does not eliminate the need for, but instead enhances the viability of permanent waste repositories. Far from being limited to waste destruction, the ATW concept also brings to the table new technologies that could be relevant for next-generation power producing reactors. In the ATW concept, spent fuel would be shipped to the ATW site where the plutonium, transuranics and selected long-lived fission products would be destroyed by fission or transmutation in their first and only pass through the

  14. Impact Forces from Tsunami-Driven Debris

    NASA Astrophysics Data System (ADS)

    Ko, H.; Cox, D. T.; Riggs, H.; Naito, C. J.; Kobayashi, M. H.; Piran Aghl, P.

    2012-12-01

    Debris driven by tsunami inundation flow has been known to be a significant threat to structures, yet we lack the constitutive equations necessary to predict debris impact force. The objective of this research project is to improve our understanding of, and predictive capabilities for, tsunami-driven debris impact forces on structures. Of special interest are shipping containers, which are virtually everywhere and which will float even when fully loaded. The forces from such debris hitting structures, for example evacuation shelters and critical port facilities such as fuel storage tanks, are currently not known. This research project focuses on the impact by flexible shipping containers on rigid columns and investigated using large-scale laboratory testing. Full-scale in-air collision experiments were conducted at Lehigh University with 20 ft shipping containers to experimentally quantify the nonlinear behavior of full scale shipping containers as they collide into structural elements. The results from the full scale experiments were used to calibrate computer models and used to design a series of simpler, 1:5 scale wave flume experiments at Oregon State University. Scaled in-air collision tests were conducted using 1:5 scale idealized containers to mimic the container behavior observed in the full scale tests and to provide a direct comparison to the hydraulic model tests. Two specimens were constructed using different materials (aluminum, acrylic) to vary the stiffness. The collision tests showed that at higher speeds, the collision became inelastic as the slope of maximum impact force/velocity decreased with increasing velocity. Hydraulic model tests were conducted using the 1:5 scaled shipping containers to measure the impact load by the containers on a rigid column. The column was instrumented with a load cell to measure impact forces, strain gages to measure the column deflection, and a video camera was used to provide the debris orientation and speed. The

  15. Image-driven pharmacokinetics: nanomedicine concentration across space and time.

    PubMed

    Brill, Dab A; MacKay, J Andrew

    2015-01-01

    Clinical pharmacokinetics (PK) primarily measures the concentration of drugs in the blood. For nanomedicines it may be more relevant to determine concentration within a target tissue. The emerging field of image-driven PK, which utilizes clinically accepted molecular imaging technology, empirically and noninvasively, measures concentration in multiple tissues. Image-driven PK represents the intersection of PK and biodistribution, combining to provide models of concentration across space and time. Image-driven PK can be used both as a research tool and in the clinic. This review explores the history of pharmacokinetics, technologies used in molecular imaging (especially positron emission tomography) and research using image-driven pharmacokinetic analysis. When standardized, image-driven PK may have significant implications in preclinical development as well as clinical optimization of targeted nanomedicines.

  16. Play and Recreation for Individuals with Disabilities: Practical Pointers.

    ERIC Educational Resources Information Center

    Grosse, Susan J., Ed.; Thompson, Donna, Ed.

    This book contains practical information that reflects new developments in sports participation for individuals with disabilities. The focus is on meeting the challenges of the outdoor environment, learning through appropriate and safe play, and keeping fit through active leisure. Specifics include practical aspects of camping and outdoor…

  17. Why Am I Learning Evolution? Pointers towards Enacted Scientific Literacy

    ERIC Educational Resources Information Center

    Olander, Clas

    2013-01-01

    This paper explores affordances in teaching evolution, especially those in which evolution is made relevant to and argued for in a grade 9 biology classroom, thus giving potential answers to the pupils' legitimate question,"'why am I learning evolution?" The aim of the paper is methodological in the sense that it explores…

  18. Disentangling the attentional deficit in schizophrenia: pointers from schizotypy.

    PubMed

    Le Pelley, M E; Schmidt-Hansen, Mia; Harris, Naomi Jane; Lunter, Catherine Maria; Morris, Charlotte Sonia

    2010-04-30

    It has been argued that schizophrenia is associated with abnormalities in the allocation of attention, and that such abnormalities extend to members of the healthy population who are high in schizotypy; however, alternative interpretations of previous experimental evidence relating to this issue are possible. We present a learned irrelevance paradigm that provides a less equivocal measure of attentional processing during learning, and demonstrate a reliable reduction in learned irrelevance among healthy participants with high scores on a dimension of schizotypy corresponding to the positive symptoms of schizophrenia. These results support the suggestion that high schizotypy (and, by extension, schizophrenia) is associated with deficits in the appropriate allocation of attention.

  19. The pediatrician and child maltreatment: principles and pointers for practice.

    PubMed

    Dubowitz, Howard; Leventhal, John M

    2014-10-01

    Child abuse and neglect are inherently challenging problems for pediatricians. It is hoped that this article makes this work easier, albeit not easy, and highlights the many ways that pediatricians can make a valuable difference in the lives of these vulnerable children and their families. PMID:25242702

  20. Living Conditions of Some Basic School Children: Pointers to Disadvantage.

    ERIC Educational Resources Information Center

    Grant, D. R. B.

    This study, conducted by the Bernard Van Leer Foundation Project for Early Childhood Education (PECE), presents the results of a survey which was carried out to identify home deficits in socioeconomically disadvantaged children's preparation for schooling. The study was conducted in Jamaica during July, August, and September, 1970, and was…

  1. Concepts as Semantic Pointers: A Framework and Computational Model

    ERIC Educational Resources Information Center

    Blouw, Peter; Solodkin, Eugene; Thagard, Paul; Eliasmith, Chris

    2016-01-01

    The reconciliation of theories of concepts based on prototypes, exemplars, and theory-like structures is a longstanding problem in cognitive science. In response to this problem, researchers have recently tended to adopt either hybrid theories that combine various kinds of representational structure, or eliminative theories that replace concepts…

  2. Automatic Tie Pointer for In-Situ Pointing Correction

    NASA Technical Reports Server (NTRS)

    Deen, Robert G/

    2011-01-01

    The MARSAUTOTIE program generates tie points for use with the Mars pointing correction software "In-Situ Pointing Correction and Rover Microlocalization," (NPO-46696) Soft ware Tech Briefs, Vol. 34, No. 9 (September 2010), page 18, in a completely automated manner, with no operator intervention. It takes the place of MARSTIE, although MARSTIE can be used to interactively edit the tie points afterwards. These tie points are used to create a mosaic whose seams (boundaries of input images) have been geometrically corrected to reduce or eliminate errors and mis-registrations. The methods used to find appropriate tie points for use in creating a mosaic are unique, having been designed to work in concert with the "MARSNAV" program to be most effective in reducing or eliminating geometric seams in a mosaic. The program takes the input images and finds overlaps according to the nominal pointing. It then finds the most interesting areas using a scene activity metric. Points with higher scene activity are more likely to correlate successfully in the next step. It then uses correlation techniques to find matching points in the overlapped image. Finally, it performs a series of steps to reduce the number of tie points to a manageable level. These steps incorporate a number of heuristics that have been devised using experience gathered by tie pointing mosaics manually during MER operations. The software makes use of the PIG library as described in "Planetary Image Geometry Library" (NPO-46658), NASA Tech Briefs, Vol. 34, No. 12 (December 2010), page 30, so it is multi-mission, applicable without change to any in-situ mission supported by PIG. The MARSAUTOTIE algorithm is automated, so it requires no user intervention. Although at the time of this reporting it has not been done, this program should be suitable for integration into a fully automated mosaic production pipeline.

  3. Decoherence of quantum fields: Pointer states and predictability

    SciTech Connect

    Anglin, J.R.; Zurek, W.H.

    1996-06-01

    We study environmentally induced decoherence of an electromagnetic field in a homogeneous, linear, dielectric medium. We derive an independent oscillator model for such an environment, which is sufficiently realistic to encompass essentially all linear physical optics. Applying the {open_quote}{open_quote}predictability sieve{close_quote}{close_quote} to the quantum field, and introducing the concept of a {open_quote}{open_quote}quantum halo,{close_quote}{close_quote} we recover the familiar dichotomy between background field configurations and photon excitations around them. We are then able to explain why a typical linear environment for the electromagnetic field will effectively render the former classically distinct, but leave the latter fully quantum mechanical. Finally, we suggest how and why quantum matter fields should suffer a very different form of decoherence. {copyright} {ital 1996 The American Physical Society.}

  4. Laser-driven nonlinear cluster dynamics

    SciTech Connect

    Fennel, Th.; Meiwes-Broer, K.-H.; Tiggesbaeumker, J.; Reinhard, P.-G.; Dinh, P. M.; Suraud, E.

    2010-04-15

    Laser excitation of nanometer-sized atomic and molecular clusters offers various opportunities to explore and control ultrafast many-particle dynamics. Whereas weak laser fields allow the analysis of photoionization, excited-state relaxation, and structural modifications on these finite quantum systems, large-amplitude collective electron motion and Coulomb explosion can be induced with intense laser pulses. This review provides an overview of key phenomena arising from laser-cluster interactions with focus on nonlinear optical excitations and discusses the underlying processes according to the current understanding. A general survey covers basic cluster properties and excitation mechanisms relevant for laser-driven cluster dynamics. Then, after an excursion in theoretical and experimental methods, results for single-photon and multiphoton excitations are reviewed with emphasis on signatures from time- and angular-resolved photoemission. A key issue of this review is the broad spectrum of phenomena arising from clusters exposed to strong fields, where the interaction with the laser pulse creates short-lived and dense nanoplasmas. The implications for technical developments such as the controlled generation of ion, electron, and radiation pulses will be addressed along with corresponding examples. Finally, future prospects of laser-cluster research as well as experimental and theoretical challenges are discussed.

  5. Data-Driven Classification of Animal Behavior

    NASA Astrophysics Data System (ADS)

    Berman, Gordon; Bialek, William; Shaevitz, Joshua

    2012-02-01

    The last decades have seen an explosion in our ability to characterize the molecular, cellular and genetic building blocks of life; the ingredients out of which we try to explain the rich and compelling behavior of living organisms. Our characterization of behavior itself, however, has advanced more slowly. Since modern ethology was founded over a century ago, behavioral experiments have focused largely on a restricted set of behaviors within the scope of a limited environment. Moreover, the set of behaviors to be examined is often user-defined, creating the potential for human bias and anthropomorphism. The research presented here describes a data-driven methodology for analyzing animal behavior, focusing on the fruit fly, Drosophila melanogaster, as a model system. Towards this end, we have built an imaging system that can track single flies as they move about a relatively unencumbered environment. Utilizing this capacity to generate large data sets of animal behavior, we have developed a method for automatically identifying behavioral states using techniques from image analysis, machine learning, and nonlinear dynamics. Identifying these states provides the starting point for many analyses and creates the possibility for automatic phenotyping of subtle behavioral traits.

  6. Magnetic Reconnection Driven by the Nernst Effect

    NASA Astrophysics Data System (ADS)

    Liu, Chang; Fox, W.; Bhattacharjee, A.; Joglekar, A.; Thomas, A.

    2013-10-01

    Magnetic reconnection in high-energy-density plasmas has been the subject of recent observations and PIC simulations. In laser-plasma experiments, laser-driven hot spots on a target can give rise to strong magnetic fields due to the Biermann battery effect. The hot spots can also produce strong heat flux perpendicular to the magnetic field, bringing into play the Nernst effect. Recently, using the Vlasov-Fokker-Planck code IMPACTA, which relies on a perturbative expansion of the electron distribution function holding ions fixed, Joglekar and Thomas (JT) have shown that the Nernst effect can play a significant role in magnetic reconnection. Since the domain of applicability of the expansion constrains the realm of validity of JT's results, we have undertaken a 2D PIC study of the Nernst effect, including complete kinetic dynamics of electrons as well as ions. We analyze the results using a broad range of dimensionless parameters, including plasma beta, the mass ratio of electrons and ions, and the Lundquist and Nernst numbers. We have found that the Nernst term contributes dominantly to support the the out-of-plane electric field upstream of the reconnection layer, consistent with JT's results. Variations on these results as a function of plasma parameters will be discussed.

  7. Data driven propulsion system weight prediction model

    NASA Technical Reports Server (NTRS)

    Gerth, Richard J.

    1994-01-01

    The objective of the research was to develop a method to predict the weight of paper engines, i.e., engines that are in the early stages of development. The impetus for the project was the Single Stage To Orbit (SSTO) project, where engineers need to evaluate alternative engine designs. Since the SSTO is a performance driven project the performance models for alternative designs were well understood. The next tradeoff is weight. Since it is known that engine weight varies with thrust levels, a model is required that would allow discrimination between engines that produce the same thrust. Above all, the model had to be rooted in data with assumptions that could be justified based on the data. The general approach was to collect data on as many existing engines as possible and build a statistical model of the engines weight as a function of various component performance parameters. This was considered a reasonable level to begin the project because the data would be readily available, and it would be at the level of most paper engines, prior to detailed component design.

  8. Passive bioventing driven by natural air exchange

    SciTech Connect

    Foor, D.C.; Zwick, T.C.; Hinchee, R.E.; Hoeppel, R.E.; Kyburg, C.; Bowling, L.

    1995-12-31

    Bioventing wells installed in the vadose zone of petroleum-contaminated sites at the Marine Corps Air Ground Combat Center (MCAGCC) in Twentynine Palms, California, naturally inhale and exhale air. This natural air exchange appears to be driven primarily by barometric pressure changes. The natural air exchange was utilized to engineer a passive bioventing system in which a valve allows only air injection and prevents soil gas extraction. The system is effective in aerating petroleum-contaminated, oxygen-limited subsurface soils. This aeration resulted in enhanced biological activity and site remediation. The bioventing wells (vent wells) were fitted with a passive valve mechanism that opens when the atmospheric pressure overcomes the internal vent well pressure. When the valve is open it permits atmospheric air to enter the vent well and infiltrate into the soil, thereby stimulating bioremediation. When the vent well pressure overcomes atmospheric pressure, the valve is closed and inhibits soil gas extraction. The vent wells are installed in a coarse sand where the depth to groundwater is approximately 220 ft (67 m). Generally, deeper vent wells produce greater flowrates. Passive airflow rates of up to 7 cfm (12 m{sup 3}/h) have been achieved at the bioventing wells.

  9. Nonequilibrium transitions driven by external dichotomous noise

    NASA Astrophysics Data System (ADS)

    Behn, U.; Schiele, K.; Teubel, A.; Kühnel, A.

    1987-06-01

    The stationary probability density P s for a class of nonlinear one-dimensional models driven by a dichotomous Markovian process (DMP) I t , can be calculated explicitly. For the specific case of the Stratonovich model, x=ax - -x 3 +I t x, the qualitative shape of P s and its support is discussed in the whole parameter region. The location of the maxima of P s shows a behavior similar to order parameters in continuous phase transitions. The possibility of a noiseinduced change from continuous to a discontinuous transition in an extended model, in which the DMP couples also to the cubic term, is discussed. The time-dependent moments can be represented as an infinite series of terms, which are determined by a recursion formula. For negative even moments the series terminates and the long-time behavior can be obtained analytically. As a function of the physical parameters, qualitative changes of this behavior may occur which can be partially related to the behavior of P s . All results reproduce those for Gaussian white noise in the corresponding limit. The influence of the finite correlation time and the discreteness of the space of states of the DMP are discussed. An extensive list of references is contained in U. Behn, K. Schiele, and A. Teubel, Wiss. Z. Karl-Marx-Univ. Leipzig, Mathem.-Naturwiss. R. 34:602 (1985).

  10. Shear-Driven Reconnection in Kinetic Models

    NASA Astrophysics Data System (ADS)

    Black, C.; Antiochos, S. K.; Germaschewski, K.; Karpen, J. T.; DeVore, C. R.; Bessho, N.

    2015-12-01

    The explosive energy release in solar eruptive phenomena is believed to be due to magnetic reconnection. In the standard model for coronal mass ejections (CME) and/or solar flares, the free energy for the event resides in the strongly sheared magnetic field of a filament channel. The pre-eruption force balance consists of an upward force due to the magnetic pressure of the sheared field countered by a downward tension due to overlying unsheared field. Magnetic reconnection disrupts this force balance; therefore, it is critical for understanding CME/flare initiation, to model the onset of reconnection driven by the build-up of magnetic shear. In MHD simulations, the application of a magnetic-field shear is a trivial matter. However, kinetic effects are dominant in the diffusion region and thus, it is important to examine this process with PIC simulations as well. The implementation of such a driver in PIC methods is challenging, however, and indicates the necessity of a true multiscale model for such processes in the solar environment. The field must be sheared self-consistently and indirectly to prevent the generation of waves that destroy the desired system. Plasma instabilities can arise nonetheless. In the work presented here, we show that we can control this instability and generate a predicted out-of-plane magnetic flux. This material is based upon work supported by the National Science Foundation under Award No. AGS-1331356.

  11. Quantifying the synchronizability of externally driven oscillators.

    PubMed

    Stefański, Andrzej

    2008-03-01

    This paper is focused on the problem of complete synchronization in arrays of externally driven identical or slightly different oscillators. These oscillators are coupled by common driving which makes an occurrence of generalized synchronization between a driving signal and response oscillators possible. Therefore, the phenomenon of generalized synchronization is also analyzed here. The research is concentrated on the cases of an irregular (chaotic or stochastic) driving signal acting on continuous-time (Duffing systems) and discrete-time (Henon maps) response oscillators. As a tool for quantifying the robustness of the synchronized state, response (conditional) Lyapunov exponents are applied. The most significant result presented in this paper is a novel method of estimation of the largest response Lyapunov exponent. This approach is based on the complete synchronization of two twin response subsystems via additional master-slave coupling between them. Examples of the method application and its comparison with the classical algorithm for calculation of Lyapunov exponents are widely demonstrated. Finally, the idea of effective response Lyapunov exponents, which allows us to quantify the synchronizability in case of slightly different response oscillators, is introduced. PMID:18377057

  12. Photonic Crystal Laser-Driven Accelerator Structures

    SciTech Connect

    Cowan, Benjamin M.

    2007-08-22

    Laser-driven acceleration holds great promise for significantly improving accelerating gradient. However, scaling the conventional process of structure-based acceleration in vacuum down to optical wavelengths requires a substantially different kind of structure. We require an optical waveguide that (1) is constructed out of dielectric materials, (2) has transverse size on the order of a wavelength, and (3) supports a mode with speed-of-light phase velocity in vacuum. Photonic crystals---structures whose electromagnetic properties are spatially periodic---can meet these requirements. We discuss simulated photonic crystal accelerator structures and describe their properties. We begin with a class of two-dimensional structures which serves to illustrate the design considerations and trade-offs involved. We then present a three-dimensional structure, and describe its performance in terms of accelerating gradient and efficiency. We discuss particle beam dynamics in this structure, demonstrating a method for keeping a beam confined to the waveguide. We also discuss material and fabrication considerations. Since accelerating gradient is limited by optical damage to the structure, the damage threshold of the dielectric is a critical parameter. We experimentally measure the damage threshold of silicon for picosecond pulses in the infrared, and determine that our structure is capable of sustaining an accelerating gradient of 300 MV/m at 1550 nm. Finally, we discuss possibilities for manufacturing these structures using common microfabrication techniques.

  13. A colalborative environment for information driven safeguards

    SciTech Connect

    Scott, Mark R; Michel, Kelly D

    2010-09-15

    For two decades, the IAEA has recognized the need for a comprehensive and strongly integrated Knowledge Management system to support its Information Driven Safeguards activities. In the past, plans for the development of such a system have progressed slowly due to concerns over costs and feasibility. In recent years, Los Alamos National Laboratory has developed a knowledge management system that could serve as the basis for an IAEA Collaborative Environment (ICE). The ICE derivative knowledge management system described in this paper addresses the challenge of living in an era of information overload coupled with certain knowledge shortfalls. The paper describes and defines a system that is flexible, yet ensures coordinated and focused collaboration, broad data evaluation capabilities, architected and organized work flows, and improved communications. The paper and demonstration of ICE will utilize a hypothetical scenario to highlight the functional features that facilitate collaboration amongst and between information analysts and inspectors. The scenario will place these two groups into a simulated planning exercise for a safeguards inspection drawing upon past data acquisitions, inspection reports, analyst conclusions, and a coordinated walk-through of a 3-D model of the facility. Subsequent to the conduct of the simulated facility inspection, the detection of an anomaly and pursuit of follow up activities will illustrate the event notification, information sharing, and collaborative capabilities of the system. The use of a collaborative environment such as ICE to fulfill the complicated knowledge management demands of the Agency and facilitate the completion of annual State Evaluation Reports will also be addressed.

  14. Hydrodynamically driven colloidal assembly in dip coating.

    PubMed

    Colosqui, Carlos E; Morris, Jeffrey F; Stone, Howard A

    2013-05-01

    We study the hydrodynamics of dip coating from a suspension and report a mechanism for colloidal assembly and pattern formation on smooth substrates. Below a critical withdrawal speed where the coating film is thinner than the particle diameter, capillary forces induced by deformation of the free surface prevent the convective transport of single particles through the meniscus beneath the film. Capillary-induced forces are balanced by hydrodynamic drag only after a minimum number of particles assemble within the meniscus. The particle assembly can thus enter the thin film where it moves at nearly the withdrawal speed and rapidly separates from the next assembly. The interplay between hydrodynamic and capillary forces produces periodic and regular structures below a critical ratio Ca(2/3)/sqrt[Bo] < 0.7, where Ca and Bo are the capillary and Bond numbers, respectively. An analytical model and numerical simulations are presented for the case of two-dimensional flow with circular particles in suspension. The hydrodynamically driven assembly documented here is consistent with stripe pattern formations observed experimentally in dip coating.

  15. Designing and operating electrostatically driven microengines

    SciTech Connect

    Rodgers, M.S.; Sniegowski, J.J.; Miller, S.L.; LaVigne, G.F.

    1998-02-01

    Microelectromechanical engines that convert the linear outputs from dual orthogonal electrostatic actuators to rotary motion were first developed in 1993. Referred to as microengines, these early devices demonstrated the potential of microelectromechanical technology, but, as expected from any first-of-its-kind device, were not yet optimized. Yield was relatively low, and the 10 micronewtons of force generated by the actuators was not always enough to ensure reliable operation. Since initial development, these engines have undergone a continuous series of significant improvements on three separate fronts: design, fabrication, and electrical activation. Although all three areas will be discussed, emphasis will be on aspects related to mechanical design and generation of the electrical waveforms used to drive these devices. Microtransmissions that dramatically increase torque will also be discussed. Electrostatically driven microengines can be operated at hundreds of thousands of revolutions per minute making large gear reduction ratios feasible; overall ratios of 3,000,000:1 have been successfully demonstrated. Today`s microengines have evolved into high endurance (one test device has seen over 7,000,000,000 revolutions), high yield, robust devices that have become the primary actuation source for MicroElectroMechanical Systems (MEMS) at Sandia National Laboratories.

  16. Data Driven Design Optimization and Its Application Data Driven Design Optimization and Its Application Data Driven Design Optimization and Its Application Data Driven Design Optimization and Its Application

    NASA Astrophysics Data System (ADS)

    Zhao, Hongxia; Icoz, Tunc; Jaluria, Yogesh; Knight, Doyle

    2003-11-01

    The Data Driven Design Optimization Methodology (DDDOM) incorporates experiment and simulation synergistically to achieve better designs in less time than conventional methods. It is developed on the basis of the advanced experimental technology (e.g., Rapid Prototyping) and computational technology (e.g., Parallel Processing, Grid Computing). The DDDOM is comprised of six elements: User Interface, Controller, Optimizer, Experiment, Surrogate Model and Simulation. The DDDOM Controller is the central element of DDDOM. It initiates experiment and simulation, monitors and coordinates their progress. The software system and its user interface are written in Perl/Tk. The DDDOM is applied to a cooling problem for electronic equipment. In this problem, two dimensional mixed convection heat transfer over two isothermal protruding heating elements (simulating electronic components) located at the bottom surface of a horizontal channel was considered. Air is the coolant fluid. The bottom plate is assumed to be insulated and the top plate is kept at the ambient temperature of the incoming air flow. The heat sources have fixed temperature. The flow conditions are defined by the mean Reynolds number (Re), Grashof number (Gr) and Prandtl number (Pr). The objective is to find the optimum heat source locations for fixed Re, Gr and Pr number such that the pressure drop will be minimized. The optimization loop is done by using a simulation code and an optimizer, CFSQP.

  17. Ecology-driven stereotypes override race stereotypes.

    PubMed

    Williams, Keelah E G; Sng, Oliver; Neuberg, Steven L

    2016-01-12

    Why do race stereotypes take the forms they do? Life history theory posits that features of the ecology shape individuals' behavior. Harsh and unpredictable ("desperate") ecologies induce fast strategy behaviors such as impulsivity, whereas resource-sufficient and predictable ("hopeful") ecologies induce slow strategy behaviors such as future focus. We suggest that individuals possess a lay understanding of ecology's influence on behavior, resulting in ecology-driven stereotypes. Importantly, because race is confounded with ecology in the United States, we propose that Americans' stereotypes about racial groups actually reflect stereotypes about these groups' presumed home ecologies. Study 1 demonstrates that individuals hold ecology stereotypes, stereotyping people from desperate ecologies as possessing faster life history strategies than people from hopeful ecologies. Studies 2-4 rule out alternative explanations for those findings. Study 5, which independently manipulates race and ecology information, demonstrates that when provided with information about a person's race (but not ecology), individuals' inferences about blacks track stereotypes of people from desperate ecologies, and individuals' inferences about whites track stereotypes of people from hopeful ecologies. However, when provided with information about both the race and ecology of others, individuals' inferences reflect the targets' ecology rather than their race: black and white targets from desperate ecologies are stereotyped as equally fast life history strategists, whereas black and white targets from hopeful ecologies are stereotyped as equally slow life history strategists. These findings suggest that the content of several predominant race stereotypes may not reflect race, per se, but rather inferences about how one's ecology influences behavior.

  18. Pressure driven flow in porous tubular membranes

    NASA Astrophysics Data System (ADS)

    Tilton, Nils; Martinand, Denis; Serre, Eric; Lueptow, Richard

    2011-11-01

    We consider the steady laminar flow of a Newtonian incompressible fluid in a porous tubular membrane with pressure-driven transmembrane flow. Due to its fundamental importance to membrane filtration systems, this flow has been studied extensively both analytically and numerically, yet a robust analytic solution has not been found. The problem is challenging due to the coupling between the transmembrane pressure and velocity with the simultaneous coupling between the axial pressure gradient and the axial velocity. We present a robust analytical solution which incorporates Darcy's law on the membrane surface. The solution is in the form of an asymptotic expansion about a small parameter related to the membrane permeability. We verify the analytical solution with comparison to 2-D spectral direct numerical simulations of ultrafiltration and microfiltration systems with typical operating conditions, as well as extreme cases of cross-flow reversal and axial flow exhaustion. In all cases, the agreement between the analytical and numerical results is excellent. Finally, we use the analytical and numerical results to provide guidelines about when common simplifying assumptions about the permeate flow may be made. Specifically, the assumptions of a parabolic axial velocity profile and uniform transmembrane velocity are valid only for small permeabilities.

  19. Scaling properties of turbulence driven shear flow

    SciTech Connect

    Yan, Z.; Tynan, G. R.; Holland, C.; Xu, M.; Muller, S. H.; Yu, J. H.

    2010-01-15

    The characteristics and scaling properties of the turbulence driven shear flow are investigated in a cylindrical laboratory plasma device. For a given plasma pressure, the density fluctuation amplitude and radial particle flux increase with the applied magnetic field. Strong flow shear is found to coexist at high magnetic fields (>700 G) with approx10 kHz drift wave turbulence, but not at low magnetic fields (<700 G). The absolute value of the divergence of the turbulent Reynolds stress at the shear layer is shown to increase with the magnetic field as well. For a fixed magnetic field, the shear flow is found to decrease as the discharge gas pressure is increased. The density fluctuation amplitude and divergence of the turbulent Reynolds stress also decrease with the plasma pressure. For both situations the cross phase between the radial and azimuthal components of the velocity is found to be a key factor to determine variations in the turbulent Reynolds stress at different magnetic fields and discharge pressures. The results show that the generation of the shear flow is related to the development of specific frequency components of the drift wave turbulence for a variety of plasma conditions. The linear stability analysis shows that the observed variation in the turbulence and shear flow with magnetic field is also consistent with a critical gradient behavior.

  20. Accelerator Driven Nuclear Energy: The Thorium Option

    SciTech Connect

    Raja, Rajendran

    2009-03-18

    Conventional nuclear reactors use enriched Uranium as fuel and produce nuclear waste which needs to be stored away for over 10,000 years.   At the current rate of use, existing sources of Uranium will last for 50-100 years.  We describe a solution to the problem that uses particle accelerators to produce fast neutrons that can be used to burn existing nuclear waste and produce energy.  Such systems, initially proposed by Carlo Rubbia and collaborators in the 1990's, are being seriously considered by many countries as a possible solution to the green energy problem.  Accelerator driven reactors operate in a sub-critical regime and, thus, are safer and can obtain energy from plentiful elements such as Thorium-232 and Uranium-238. What is missing is the high intensity (10MW) accelerator that produces 1 GeV protons. We will describe scenarios which if implemented will make such systems a reality.  

  1. Magnetohydrodynamic stability of stochastically driven accretion flows.

    PubMed

    Nath, Sujit Kumar; Mukhopadhyay, Banibrata; Chattopadhyay, Amit K

    2013-07-01

    We investigate the evolution of magnetohydrodynamic (or hydromagnetic as coined by Chandrasekhar) perturbations in the presence of stochastic noise in rotating shear flows. The particular emphasis is the flows whose angular velocity decreases but specific angular momentum increases with increasing radial coordinate. Such flows, however, are Rayleigh stable but must be turbulent in order to explain astrophysical observed data and, hence, reveal a mismatch between the linear theory and observations and experiments. The mismatch seems to have been resolved, at least in certain regimes, in the presence of a weak magnetic field, revealing magnetorotational instability. The present work explores the effects of stochastic noise on such magnetohydrodynamic flows, in order to resolve the above mismatch generically for the hot flows. We essentially concentrate on a small section of such a flow which is nothing but a plane shear flow supplemented by the Coriolis effect, mimicking a small section of an astrophysical accretion disk around a compact object. It is found that such stochastically driven flows exhibit large temporal and spatial autocorrelations and cross-correlations of perturbation and, hence, large energy dissipations of perturbation, which generate instability. Interestingly, autocorrelations and cross-correlations appear independent of background angular velocity profiles, which are Rayleigh stable, indicating their universality. This work initiates our attempt to understand the evolution of three-dimensional hydromagnetic perturbations in rotating shear flows in the presence of stochastic noise.

  2. Capillarity driven motion of solid film wedges

    SciTech Connect

    Wong, H.; Miksis, M.J.; Voorhees, P.W.; Davis, S.H.

    1997-06-01

    A solid film freshly deposited on a substrate may form a non-equilibrium contact angle with the substrate, and will evolve. This morphological evolution near the contact line is investigated by studying the motion of a solid wedge on a substrate. The contact angle of the wedge changes at time t = 0 from the wedge angle {alpha} to the equilibrium contact angle {beta}, and its effects spread into the wedge via capillarity-driven surface diffusion. The film profiles at different times are found to be self-similar, with the length scale increasing as t{sup 1 4}. The self-similar film profile is determined numerically by a shooting method for {alpha} and {beta} between 0 and 180. In general, the authors find that the film remains a wedge when {alpha} = {beta}. For {alpha} < {beta}, the film retracts, whereas for {alpha} > {beta}, the film extends. For {alpha} = 90{degree}, the results describe the growth of grain-boundary grooves for arbitrary dihedral angles. For {beta} = 90{degree}, the solution also applies to a free-standing wedge, and the thin-wedge profiles agree qualitatively with those observed in transmission electron microscope specimens.

  3. Computational dynamics of acoustically driven microsphere systems.

    PubMed

    Glosser, Connor; Piermarocchi, Carlo; Li, Jie; Dault, Dan; Shanker, B

    2016-01-01

    We propose a computational framework for the self-consistent dynamics of a microsphere system driven by a pulsed acoustic field in an ideal fluid. Our framework combines a molecular dynamics integrator describing the dynamics of the microsphere system with a time-dependent integral equation solver for the acoustic field that makes use of fields represented as surface expansions in spherical harmonic basis functions. The presented approach allows us to describe the interparticle interaction induced by the field as well as the dynamics of trapping in counter-propagating acoustic pulses. The integral equation formulation leads to equations of motion for the microspheres describing the effect of nondissipative drag forces. We show (1) that the field-induced interactions between the microspheres give rise to effective dipolar interactions, with effective dipoles defined by their velocities and (2) that the dominant effect of an ultrasound pulse through a cloud of microspheres gives rise mainly to a translation of the system, though we also observe both expansion and contraction of the cloud determined by the initial system geometry. PMID:26871188

  4. Auxin-driven patterning with unidirectional fluxes.

    PubMed

    Cieslak, Mikolaj; Runions, Adam; Prusinkiewicz, Przemyslaw

    2015-08-01

    The plant hormone auxin plays an essential role in the patterning of plant structures. Biological hypotheses supported by computational models suggest that auxin may fulfil this role by regulating its own transport, but the plausibility of previously proposed models has been questioned. We applied the notion of unidirectional fluxes and the formalism of Petri nets to show that the key modes of auxin-driven patterning-the formation of convergence points and the formation of canals-can be implemented by biochemically plausible networks, with the fluxes measured by dedicated tally molecules or by efflux and influx carriers themselves. Common elements of these networks include a positive feedback of auxin efflux on the allocation of membrane-bound auxin efflux carriers (PIN proteins), and a modulation of this allocation by auxin in the extracellular space. Auxin concentration in the extracellular space is the only information exchanged by the cells. Canalization patterns are produced when auxin efflux and influx act antagonistically: an increase in auxin influx or concentration in the extracellular space decreases the abundance of efflux carriers in the adjacent segment of the membrane. In contrast, convergence points emerge in networks in which auxin efflux and influx act synergistically. A change in a single reaction rate may result in a dynamic switch between these modes, suggesting plausible molecular implementations of coordinated patterning of organ initials and vascular strands predicted by the dual polarization theory.

  5. Query-Driven Visualization and Analysis

    SciTech Connect

    Ruebel, Oliver; Bethel, E. Wes; Prabhat, Mr.; Wu, Kesheng

    2012-11-01

    This report focuses on an approach to high performance visualization and analysis, termed query-driven visualization and analysis (QDV). QDV aims to reduce the amount of data that needs to be processed by the visualization, analysis, and rendering pipelines. The goal of the data reduction process is to separate out data that is "scientifically interesting'' and to focus visualization, analysis, and rendering on that interesting subset. The premise is that for any given visualization or analysis task, the data subset of interest is much smaller than the larger, complete data set. This strategy---extracting smaller data subsets of interest and focusing of the visualization processing on these subsets---is complementary to the approach of increasing the capacity of the visualization, analysis, and rendering pipelines through parallelism. This report discusses the fundamental concepts in QDV, their relationship to different stages in the visualization and analysis pipelines, and presents QDV's application to problems in diverse areas, ranging from forensic cybersecurity to high energy physics.

  6. Transient Mixing Driven by Buoyancy Flows

    NASA Technical Reports Server (NTRS)

    Duval, W. M. B.; Batur, C.; Zhong, H.

    2002-01-01

    Mixing driven by buoyancy-induced flows is of particular interest to microgravity processes, as the body force that governs the intensity of flow fields can be directly controlled. We consider a model experimental system to explore the dynamics of mixing which employs two miscible liquids inside a cavity separated initially by a divider. The two liquids are oriented vertically inside a rectangular cavity with constant width and height, and varying depths to span the range of a Hele-Shaw cell to a 3-D configuration. The two miscible liquids can be sufficiently diluted and died, for example water and deuterium oxide, such that a distinct interface exists across the divider. The transient mixing characteristic of the two fluids is addressed by following the Lagrangian history of the interface for various aspect ratios in the z-plane (depth variation) as well as a range of pulling velocities of the divider. The mixing characteristics of the two fluids are quantified from measurement of the length stretch of the interface and its flow field using respectively image processing techniques and Particle Imaging Velocimetry. Scaling analysis shows that the length stretch depends on four governing parameters, namely the Grashof number (Gr), Schmidt number (Sc), aspect ratio (Ar), and Reynolds number (Re). Variation of the Schmidt number is taken into account through thermophysical property variation. Thus our problem reduces to a codimension three bifurcation in parametric space for Gr, Ar, and Re.

  7. Driven synchronization in random networks of oscillators.

    PubMed

    Hindes, Jason; Myers, Christopher R

    2015-07-01

    Synchronization is a universal phenomenon found in many non-equilibrium systems. Much recent interest in this area has overlapped with the study of complex networks, where a major focus is determining how a system's connectivity patterns affect the types of behavior that it can produce. Thus far, modeling efforts have focused on the tendency of networks of oscillators to mutually synchronize themselves, with less emphasis on the effects of external driving. In this work, we discuss the interplay between mutual and driven synchronization in networks of phase oscillators of the Kuramoto type, and explore how the structure and emergence of such states depend on the underlying network topology for simple random networks with a given degree distribution. We find a variety of interesting dynamical behaviors, including bifurcations and bistability patterns that are qualitatively different for heterogeneous and homogeneous networks, and which are separated by a Takens-Bogdanov-Cusp singularity in the parameter region where the coupling strength between oscillators is weak. Our analysis is connected to the underlying dynamics of oscillator clusters for important states and transitions. PMID:26232970

  8. Electrically Driven Polariton Light Emitting Devices

    NASA Astrophysics Data System (ADS)

    Tsintzos, Simeon I.; Pelekanos, Nikolaos T.; Savvidis, Pavlos G.

    The aim of this chapter is to highlight the recent progress in the rapidly developing field of electrically driven polariton devices. The unprecedented potential of polariton-based devices owes its origin mainly to the bosonic property of polaritons to condense in the same final state, thus requiring no population inversion to achieve lasing. Consequently, it is widely believed that the threshold of a polariton laser is at least two orders of magnitude lower than that of a conventional semiconductor photon laser operating in the weak-coupling regime [C. Weisbuch, M. Nishioka, A. Ishikawa, Y. Arakawa, Phys. Rev. Lett. 69, 3314-3317 (1992)]. This makes polariton lasers extremely promising as ultralow threshold lasers or as low-power sources of coherent and nonclassical light. Electrical injection of these entangled light-matter states is a key step toward the realisation of practical, compact devices. Recent demonstrations of electrically pumped polariton LEDs in organic as well as inorganic material systems operating up to room temperature have highlighted the potential of such devices for real-world polariton-based applications in optoelectronics.

  9. Thermally driven motion of strongly heated fluids

    NASA Astrophysics Data System (ADS)

    Deboer, P. C. T.

    1983-02-01

    Approximate equations which are derived for the thermally driven motion of strongly heated, shallow fluids were examined. The equations follow from formal perturbation theory, using the nondimensionalized depth epsilon of the fluid as the smaller parameter. They govern the zeroth order temperature, pressure, and density. The method used is also applied to a weakly heated, deep fluid, using the nondimensionalized strength delta' of the heat source distribution as the small parameter. In the later case, the equations govern the first order perturbations in temperature, pressure, and density, while the unperturbed situation is the so called adiabatic state. The Boussinesq equations are recovered for a weakly heated, shallow fluid, independent of the relative magnitude of delta' and epsilon. For the case of a weakly heated, shallow ideal gas maintained at constant volume and heated throughout the volume, the equations account for the effect of perturbation pressure on perturbation density and on compression heating. A final case considered is that of a strongly heated, deep liquid with a small coefficient of thermal expansion. The energy equation for this case is found to be significantly different from that for a weakly heated, deep liquid. For two dimensional geometries, the various sets of equations derived are amendable to a common numerical method of solution.

  10. Accelerator Driven Nuclear Energy: The Thorium Option

    ScienceCinema

    Raja, Rajendran

    2016-07-12

    Conventional nuclear reactors use enriched Uranium as fuel and produce nuclear waste which needs to be stored away for over 10,000 years.   At the current rate of use, existing sources of Uranium will last for 50-100 years.  We describe a solution to the problem that uses particle accelerators to produce fast neutrons that can be used to burn existing nuclear waste and produce energy.  Such systems, initially proposed by Carlo Rubbia and collaborators in the 1990's, are being seriously considered by many countries as a possible solution to the green energy problem.  Accelerator driven reactors operate in a sub-critical regime and, thus, are safer and can obtain energy from plentiful elements such as Thorium-232 and Uranium-238. What is missing is the high intensity (10MW) accelerator that produces 1 GeV protons. We will describe scenarios which if implemented will make such systems a reality.  

  11. Ultrafast electronic dynamics driven by nuclear motion

    NASA Astrophysics Data System (ADS)

    Vendrell, Oriol

    2016-05-01

    The transfer of electrical charge on a microscopic scale plays a fundamental role in chemistry, in biology, and in technological applications. In this contribution, we will discuss situations in which nuclear motion plays a central role in driving the electronic dynamics of photo-excited or photo-ionized molecular systems. In particular, we will explore theoretically the ultrafast transfer of a double electron hole between the functional groups of glycine after K-shell ionization and subsequent Auger decay. Although a large energy gap of about 15 eV initially exists between the two electronic states involved and coherent electronic dynamics play no role in the hole transfer, we will illustrate how the double hole can be transferred within 3 to 4 fs between both functional ends of the glycine molecule driven solely by specific nuclear displacements and non-Born-Oppenheimer effects. This finding challenges the common wisdom that nuclear dynamics of the molecular skeleton are unimportant for charge transfer processes at the few-femtosecond time scale and shows that they can even play a prominent role. We thank the Hamburg Centre for Ultrafast Imaging and the Volkswagen Foundation for financial support.

  12. How surfactants influence evaporation-driven flows

    NASA Astrophysics Data System (ADS)

    Liepelt, Robert; Marin, Alvaro; Rossi, Massimiliano; Kähler, Christian J.

    2014-11-01

    Capillary flows appear spontaneously in sessile evaporating drops and give rise to particle accumulation around the contact lines, commonly known as coffee-stain effect (Deegan et al., Nature, 1997). On the other hand, out-of-equilibrium thermal effects may induce Marangoni flows in the droplet's surface that play an important role in the flow patterns and in the deposits left on the substrate. Some authors have argued that contamination or the presence of surfactants might reduce or eventually totally annul the Marangoni flow (Hu & Larson, J. Phys. Chem. B, 2006). On the contrary, others have shown an enhancement of the reverse surface flow (Sempels et al., Nat. Commun., 2012). In this work, we employ Astigmatic Particle Tracking Velocimetry (APTV) to obtain the 3D3C evaporation-driven flow in both bulk and droplet's surface, using surfactants of different ionic characters and solubility. Our conclusions lead to a complex scenario in which different surfactants and concentrations yield very different surface-flow patterns, which eventually might influence the colloidal deposition patterns.

  13. User-driven segmentation approach: interactive snakes

    NASA Astrophysics Data System (ADS)

    Kunert, Tobias; Heiland, Marc; Meinzer, Hans-Peter

    2002-05-01

    For diagnostics and therapy planning, the segmentation of medical images is an important pre-processing step. Currently, manual segmentation tools are most common in clinical routine. Because the work is very time-consuming, there is a large interest in tools assisting the physician. Most of the known segmentation techniques suffer from an inadequate user interface, which prevents their use in a clinical environment. The segmentation of medical images is very difficult. A promising method to overcome difficulties such as imaging artifacts are active contour models. In order to enhance the clinical usability, we propose a user-driven segmentation approach. Following this way, we developed a new segmentation method, which we call interactive snakes. Thereto, we elaborated an interaction style which is more intuitive to the clinical user and derived a new active contour model. The segmentation method provides a very tight coupling with the user. The physician is interactively attaching boundary markers to the image, whereby he is able to bring in his knowledge. At the same time, the segmentation is updated in real-time. Interactive snakes are a comprehensible segmentation method for the clinical use. It is reasonable to employ them both as a core tool and as an editing tool for incorrect results.

  14. Spin-current-driven thermoelectric coating.

    PubMed

    Kirihara, Akihiro; Uchida, Ken-ichi; Kajiwara, Yosuke; Ishida, Masahiko; Nakamura, Yasunobu; Manako, Takashi; Saitoh, Eiji; Yorozu, Shinichi

    2012-06-17

    Energy harvesting technologies, which generate electricity from environmental energy, have been attracting great interest because of their potential to power ubiquitously deployed sensor networks and mobile electronics. Of these technologies, thermoelectric (TE) conversion is a particularly promising candidate, because it can directly generate electricity from the thermal energy that is available in various places. Here we show a novel TE concept based on the spin Seebeck effect, called 'spin-thermoelectric (STE) coating', which is characterized by a simple film structure, convenient scaling capability, and easy fabrication. The STE coating, with a 60-nm-thick bismuth-substituted yttrium iron garnet (Bi:YIG) film, is applied by means of a highly efficient process on a non-magnetic substrate. Notably, spin-current-driven TE conversion is successfully demonstrated under a temperature gradient perpendicular to such an ultrathin STE-coating layer (amounting to only 0.01% of the total sample thickness). We also show that the STE coating is applicable even on glass surfaces with amorphous structures. Such a versatile implementation of the TE function may pave the way for novel applications making full use of omnipresent heat.

  15. Field-driven dynamics of nematic microcapillaries

    NASA Astrophysics Data System (ADS)

    Khayyatzadeh, Pouya; Fu, Fred; Abukhdeir, Nasser Mohieddin

    2015-12-01

    Polymer-dispersed liquid-crystal (PDLC) composites long have been a focus of study for their unique electro-optical properties which have resulted in various applications such as switchable (transparent or translucent) windows. These composites are manufactured using desirable "bottom-up" techniques, such as phase separation of a liquid-crystal-polymer mixture, which enable production of PDLC films at very large scales. LC domains within PDLCs are typically spheroidal, as opposed to rectangular for an LCD panel, and thus exhibit substantially different behavior in the presence of an external field. The fundamental difference between spheroidal and rectangular nematic domains is that the former results in the presence of nanoscale orientational defects in LC order while the latter does not. Progress in the development and optimization of PDLC electro-optical properties has progressed at a relatively slow pace due to this increased complexity. In this work, continuum simulations are performed in order to capture the complex formation and electric field-driven switching dynamics of approximations of PDLC domains. Using a simplified elliptic cylinder (microcapillary) geometry as an approximation of spheroidal PDLC domains, the effects of geometry (aspect ratio), surface anchoring, and external field strength are studied through the use of the Landau-de Gennes model of the nematic LC phase.

  16. Performance Driven Placement Procedure for Low Power

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Masaya; Terai, Hidekazu

    Deep-Sub-Micron (DSM) technologies of 0.18μm and below enable the integration of logical circuits having more than 10 million gates. In such a DSM technology, it’s important to consider reducing power consumption, improving interconnection delay, and dispersing wire congestion at initial phase of layout design. In this paper, we proposed a novel performance-driven placement algorithm. The proposed algorithm based on Genetic Algorithm(GA) has a two-level hierarchical structure. For selection control, new objective functions are introduced for reducing power consumption, improving interconnection delay and dispersing wire congestion. Studies on floor planning and cell placement have been reported as being applications of GA to the LSI layout problem. However, no studies have ever seen the effect of applying GA in consideration of power, delay and congestion. Results show improvement of 11.7% for the total wire length of the nets with high SW rate, 22.5% for the worst path delay and 15.9% for wire congestion on average.

  17. Surface Wave Driven Air-Water Plasmas

    NASA Astrophysics Data System (ADS)

    Tatarova, Elena; Henriques, Julio; Ferreira, Carlos

    2013-09-01

    The performance of a surface wave driven air-water plasma source operating at atmospheric pressure and 2.45 GHz has been analyzed. A 1D model has been developed in order to describe in detail the creation and loss processes of active species of interest and to provide a complete characterization of the axial structure of the source, including the discharge and the afterglow zones. The main electron creation channel was found to be the associative ionization process N +O -->NO+ + e. The NO(X) relative density in the afterglow plasma jet ranges from 1.2% to 1.6% depending on power and water percentage according to the model predictions and the measurements. Other types of species such as NO2 and nitrous acid HNO2 have also been detected by mass and FT-IR spectroscopy. Furthermore, high densities of O2(a1Δg) singlet delta oxygen molecules and OH radicals (1% and 5%, respectively) can be achieved in the discharge zone. In the late afterglow the O2(a1Δg) density is about 0.1% of the total density. The plasma source has a flexible operation and potential for channeling the energy in ways that maximize the density of active species of interest. This study was funded by the Foundation for Science and Technology, Portuguese Ministry of Education and Science, under the research contract PTDC/FIS/108411/2008.

  18. Data flow machine for data driven computing

    DOEpatents

    Davidson, George S.; Grafe, Victor G.

    1995-01-01

    A data flow computer which of computing is disclosed which utilizes a data driven processor node architecture. The apparatus in a preferred embodiment includes a plurality of First-In-First-Out (FIFO) registers, a plurality of related data flow memories, and a processor. The processor makes the necessary calculations and includes a control unit to generate signals to enable the appropriate FIFO register receiving the result. In a particular embodiment, there are three FIFO registers per node: an input FIFO register to receive input information form an outside source and provide it to the data flow memories; an output FIFO register to provide output information from the processor to an outside recipient; and an internal FIFO register to provide information from the processor back to the data flow memories. The data flow memories are comprised of four commonly addressed memories. A parameter memory holds the A and B parameters used in the calculations; an opcode memory holds the instruction; a target memory holds the output address; and a tag memory contains status bits for each parameter. One status bit indicates whether the corresponding parameter is in the parameter memory and one status but to indicate whether the stored information in the corresponding data parameter is to be reused. The tag memory outputs a "fire" signal (signal R VALID) when all of the necessary information has been stored in the data flow memories, and thus when the instruction is ready to be fired to the processor.

  19. Data flow machine for data driven computing

    DOEpatents

    Davidson, G.S.; Grafe, V.G.

    1988-07-22

    A data flow computer and method of computing is disclosed which utilizes a data driven processor node architecture. The apparatus in a preferred embodiment includes a plurality of First-In-First-Out (FIFO) registers, a plurality of related data flow memories, and a processor. The processor makes the necessary calculations and includes a control unit to generate signals to enable the appropriate FIFO register receiving the result. In a particular embodiment, there are three FIFO registers per node: an input FIFO register to receive input information from an outside source and provide it to the data flow memories; an output FIFO register to provide output information from the processor to an outside recipient; and an internal FIFO register to provide information from the processor back to the data flow memories. The data flow memories are comprised of four commonly addressed memories. A parameter memory holds the A and B parameters used in the calculations; an opcode memory holds the instruction; a target memory holds the output address; and a tag memory contains status bits for each parameter. One status bit indicates whether the corresponding parameter is in the parameter memory and one status bit to indicate whether the stored information in the corresponding data parameter is to be reused. The tag memory outputs a ''fire'' signal (signal R VALID) when all of the necessary information has been stored in the data flow memories, and thus when the instruction is ready to be fired to the processor. 11 figs.

  20. Control logic for exhaust gas driven turbocharger

    SciTech Connect

    Adeff, G.A.

    1991-12-31

    This patent describes a method of controlling an exhaust gas driven turbocharger supplying charge air for an internal combustion engine powering vehicle, the turbocharger being adjustable from a normal mode to a power mode in which the charge air available to the engine during vehicle acceleration is increased over that available when the turbocharger is in the normal mode, the vehicle including engine power control means switchable by the vehicle operator from a normal mode to a power mode so that the vehicle operator may selectively elect either the normal mode or the power mode, comprising the steps of measuring the speed of the vehicle, permitting the vehicle operator to elect either the power mode or the normal mode for a subsequent vehicle acceleration, and then adjusting the turbocharger to the power mode when the speed of the vehicle is less than a predetermined reference speed and the vehicle operator has elected to power mode to increase the charge air available to the engine and thereby increasing engine power on a subsequent acceleration of the vehicle.

  1. Data-Driven Detection of Prominent Objects.

    PubMed

    Rodriguez-Serrano, Jose A; Larlus, Diane; Dai, Zhenwen

    2016-10-01

    This article deals with the detection of prominent objects in images. As opposed to the standard approaches based on sliding windows, we study a fundamentally different solution by formulating the supervised prediction of a bounding box as an image retrieval task. Indeed, given a global image descriptor, we find the most similar images in an annotated dataset, and transfer the object bounding boxes. We refer to this approach as data-driven detection (DDD). Our key novelty is to design or learn image similarities that explicitly optimize some aspect of the transfer unlike previous work which uses generic representations and unsupervised similarities. In a first variant, we explicitly learn to transfer, by adapting a metric learning approach to work with image and bounding box pairs. Second, we use a representation of images as object probability maps computed from low-level patch classifiers. Experiments show that these two contributions yield in some cases comparable or better results than standard sliding window detectors - despite its conceptual simplicity and run-time efficiency. Our third contribution is an application of prominent object detection, where we improve fine-grained categorization by pre-cropping images with the proposed approach. Finally, we also extend the proposed approach to detect multiple parts of rigid objects. PMID:26700971

  2. A quasilinear formulation of turbulence driven current

    SciTech Connect

    McDevitt, C. J.; Tang, Xian-Zhu; Guo, Zehua

    2014-02-15

    Non-inductive current drive mechanisms, such as the familiar neoclassical bootstrap current correspond to an essential component to the realization of steady state tokamak operation. In this work, we discuss a novel collisionless mechanism through which a mean plasma current may be driven in the presence of microturbulence. In analogy with the traditional neoclassical bootstrap current drive mechanism, in which the collisional equilibrium established between trapped and passing electrons results in the formation of a steady state plasma current, here we show that resonant scattering of electrons by drift wave microturbulence provides an additional means of determining the equilibrium between trapped and passing electrons. The resulting collisionless equilibrium is shown to result in the formation of an equilibrium current whose magnitude is a function of the thermodynamic forces. A mean field formulation is utilized to incorporate the above components into a unified framework through which both collisional as well as collisionless current drive mechanisms may be self-consistently treated. Utilizing a linearized Fokker-Planck collision operator, the plasma current in the presence of both collisions as well as turbulent stresses is computed, allowing for the relative strength of these two mechanisms to be quantified as a function of collisionality and fluctuation amplitude.

  3. Hydrodynamically Driven Colloidal Assembly in Dip Coating

    NASA Astrophysics Data System (ADS)

    Colosqui, Carlos E.; Morris, Jeffrey F.; Stone, Howard A.

    2013-05-01

    We study the hydrodynamics of dip coating from a suspension and report a mechanism for colloidal assembly and pattern formation on smooth substrates. Below a critical withdrawal speed where the coating film is thinner than the particle diameter, capillary forces induced by deformation of the free surface prevent the convective transport of single particles through the meniscus beneath the film. Capillary-induced forces are balanced by hydrodynamic drag only after a minimum number of particles assemble within the meniscus. The particle assembly can thus enter the thin film where it moves at nearly the withdrawal speed and rapidly separates from the next assembly. The interplay between hydrodynamic and capillary forces produces periodic and regular structures below a critical ratio Ca2/3/Bo<0.7, where Ca and Bo are the capillary and Bond numbers, respectively. An analytical model and numerical simulations are presented for the case of two-dimensional flow with circular particles in suspension. The hydrodynamically driven assembly documented here is consistent with stripe pattern formations observed experimentally in dip coating.

  4. Measurements of gravity driven granular channel flows

    NASA Astrophysics Data System (ADS)

    Facto, Kevin

    This dissertation presents experiments that studied two gravity driven granular channel flows. The first experiment used magnetic resonance imaging to measure the density and displacement distributions of poppy seeds flowing in a rough walled channel. Time-averaged measurements of normalized velocity and density showed little flow speed dependence. Instantaneous measurements, however, showed marked velocity dependence in the displacement distributions. There was evidence of aperiodic starting and stopping at lower flow speeds and the onset of density waves on a continuous flow at higher speeds. The second experiment measured forces in all three spatial directions at the boundary of a flow of steel balls. The relationship between the normal and the tangential forces were examined statistically and compared to the Coulomb friction model. For both large and small forces, the tangential and normal forces are unrelated, as there appears to be a strong tendency for the tangential force to maintain a value that will bear the weight the weight of the particles in flow.

  5. Thermal motion of athermal driven grains

    NASA Astrophysics Data System (ADS)

    Ojha, Rajesh; Durian, D. J.; Dixon, P. K.

    2001-03-01

    The uniform upward gas flow in a gas-fluidized bed provides a homogeneous driving force. This allows a controlled study of the transition of a granular material from a static to a fluid-like state. Macroscopic properties of gas-fluidized beds, such as bed height, volume fraction, and gas pressure drop have been well-studied. However, experimental research on the dynamics of individual grains is lacking. Here, we use a scaled-up fluidized bed to observe grain motion. Our bed consists of a monolayer of ping-pong balls fluidized with air. High-speed photography allows us to track ball motions with high temporal resolution. From the images, we extract ball positions, velocities, and net forces due to the air turbulence. In the case of a lone ball, we find that a simple statistical mechanics model accurately describes its position, velocity, and energy distributions. Namely, it behaves exactly like a thermally-excited particle in a harmonic potential well. If such behavior holds for multiple balls, we will be able to develop a statistical mechanics description of grain interactions in an athermal driven system.

  6. STREAMER WAVES DRIVEN BY CORONAL MASS EJECTIONS

    SciTech Connect

    Chen, Y.; Song, H. Q.; Li, B.; Xia, L. D.; Wu, Z.; Fu, H.; Li Xing

    2010-05-01

    Between 2004 July 5 and July 7, two intriguing fast coronal mass ejection (CME)-streamer interaction events were recorded by the Large Angle and Spectrometric Coronagraph. At the beginning of the events, the streamer was pushed aside from its equilibrium position upon the impact of the rapidly outgoing and expanding ejecta; then, the streamer structure, mainly the bright streamer belt, exhibited elegant large-scale sinusoidal wavelike motions. The motions were apparently driven by the restoring magnetic forces resulting from the CME impingement, suggestive of magnetohydrodynamic kink mode propagating outward along the plasma sheet of the streamer. The mode is supported collectively by the streamer-plasma sheet structure and is therefore named 'streamer wave' in the present study. With the white light coronagraph data, we show that the streamer wave has a period of about 1 hr, a wavelength varying from 2 to 4 solar radii, an amplitude of about a few tens of solar radii, and a propagating phase speed in the range 300-500 km s{sup -1}. We also find that there is a tendency for the phase speed to decline with increasing heliocentric distance. These observations provide good examples of large-scale wave phenomena carried by coronal structures and have significance in developing seismological techniques for diagnosing plasma and magnetic parameters in the outer corona.

  7. Alternator-driven, magnetically switched modulator

    NASA Astrophysics Data System (ADS)

    Kihara, R.; Kirbie, H. C.

    The technique of magnetically switching high-power pulses was recently revitalized with the development of amorphous magnetic alloys and the new power conditioning requirements of pulsed lasers and high-brightness particle accelerators. The most common magnetic switching technique for generating high-repetition-rate pulses consists of a dc power supply, a triggered switch (thyratron or solid-state), and a repeated network of magnetic switches and capacitors. The life of this type of pulser is limited by the aging of liquid and solid dielectric materials and by the reliability of the triggered switch. An alternator-driven, magnetically switched modulator differs from the conventional magnetic modulator in the replacement of the dc power supply and triggered switch with a high-frequency motor-generator set and an all-magnetic circuit. The power conditioning network converts each cycle of the applied ac power into a single, compressed, unipolar pulse. Consequently, the modulator produces a train of pulses with an interpulse separation equal to the period of the alternator. Additional compression can be attained by the addition of successive stages of magnetic switching. The absence of active switches within the network improves the system reliability and extends the service life of the modulator to the limits of component insulation fatigue and alternator bearing wear. This style of magnetic pulse compression was first described by Melville and reproduced at LLNL in order to quantify the network efficiency, jitter and reliability when modern magnetic materials are employed.

  8. Computational dynamics of acoustically driven microsphere systems.

    PubMed

    Glosser, Connor; Piermarocchi, Carlo; Li, Jie; Dault, Dan; Shanker, B

    2016-01-01

    We propose a computational framework for the self-consistent dynamics of a microsphere system driven by a pulsed acoustic field in an ideal fluid. Our framework combines a molecular dynamics integrator describing the dynamics of the microsphere system with a time-dependent integral equation solver for the acoustic field that makes use of fields represented as surface expansions in spherical harmonic basis functions. The presented approach allows us to describe the interparticle interaction induced by the field as well as the dynamics of trapping in counter-propagating acoustic pulses. The integral equation formulation leads to equations of motion for the microspheres describing the effect of nondissipative drag forces. We show (1) that the field-induced interactions between the microspheres give rise to effective dipolar interactions, with effective dipoles defined by their velocities and (2) that the dominant effect of an ultrasound pulse through a cloud of microspheres gives rise mainly to a translation of the system, though we also observe both expansion and contraction of the cloud determined by the initial system geometry.

  9. Drag in a resonantly driven polariton fluid

    NASA Astrophysics Data System (ADS)

    Berceanu, A. C.; Cancellieri, E.; Marchetti, F. M.

    2012-06-01

    We study the linear response of a coherently driven polariton fluid in the pump-only configuration scattering against a point-like defect and evaluate analytically the drag force exerted by the fluid on the defect. When the system is excited near the bottom of the lower polariton dispersion, the sign of the interaction-renormalised pump detuning classifies the collective excitation spectra into three different categories (Ciuti and Carusotto 2005 Phys. Status Solidi b 242 2224): linear for zero, diffusive-like for positive and gapped for negative detuning. We show that both cases of zero and positive detuning share a qualitatively similar crossover of the drag force from the subsonic to the supersonic regime as a function of the fluid velocity, with a critical velocity given by the speed of sound found for the linear regime. In contrast, for gapped spectra, we find that the critical velocity exceeds the speed of sound. In all cases, the residual drag force in the subcritical regime depends on the polariton lifetime only. Also, well below the critical velocity, the drag force varies linearly with the polariton lifetime, in agreement with previous work (Cancellieri et al 2010 Phys. Rev. B 82 224512), where the drag was determined numerically for a finite-size defect.

  10. Drag in a resonantly driven polariton fluid.

    PubMed

    Berceanu, A C; Cancellieri, E; Marchetti, F M

    2012-06-13

    We study the linear response of a coherently driven polariton fluid in the pump-only configuration scattering against a point-like defect and evaluate analytically the drag force exerted by the fluid on the defect. When the system is excited near the bottom of the lower polariton dispersion, the sign of the interaction-renormalised pump detuning classifies the collective excitation spectra into three different categories (Ciuti and Carusotto 2005 Phys. Status Solidi b 242 2224): linear for zero, diffusive-like for positive and gapped for negative detuning. We show that both cases of zero and positive detuning share a qualitatively similar crossover of the drag force from the subsonic to the supersonic regime as a function of the fluid velocity, with a critical velocity given by the speed of sound found for the linear regime. In contrast, for gapped spectra, we find that the critical velocity exceeds the speed of sound. In all cases, the residual drag force in the subcritical regime depends on the polariton lifetime only. Also, well below the critical velocity, the drag force varies linearly with the polariton lifetime, in agreement with previous work (Cancellieri et al 2010 Phys. Rev. B 82 224512), where the drag was determined numerically for a finite-size defect.

  11. Surface Tension Driven Convection Experiment (STDCE)

    NASA Technical Reports Server (NTRS)

    Ostrach, S.; Kamotani, Y.

    1996-01-01

    This document reports the results obtained from the Surface Tension Driven Convection Experiment (STDCE) conducted aboard the USML-1 Spacelab in 1992. The experiments used 10 cSt silicone oil placed in an open circular container that was 10 cm wide and 5 cm deep. Thermocapillary flow was induced by using either a cylindrical heater placed along the container centerline or by a CO2 laser. The tests were conducted under various power settings, laser beam diameters, and free surface shapes. Thermistors located at various positions in the test section recorded the temperature of the fluid, heater, walls, and air. An infrared imager was used to measure the free surface temperature. The flow field was studied by flow visualization and the data was analyzed by a PTV technique. The results from the flow visualization and the temperature measurements are compared with the numerical analysis that was conducted in conjunction with the experiment. The compared results include the experimental and numerical velocity vector plots, the streamline plots, the fluid temperature, and the surface temperature distribution.

  12. A digital driven right leg circuit.

    PubMed

    Haberman, Marcelo; Spinelli, Enrique

    2010-01-01

    A novel scheme and a digital approach to the Driven Right Leg Circuit (DRL) are presented. It presents an ultra high common mode (CM) reduction of power line interference (higher than 80dB) without endangering stability. This improves by 40-50dB the CM reduction provided by a classical analog DRL, retaining the same stability criterion. The improvement comes from the inclusion of a high Q resonator in parallel with the common mode amplifier. It provides a large gain at power line frequency (50/60 Hz) whereas it does not significantly affect the open loop gain for high frequencies. The proposed scheme can be thought as an analog circuit, but the accuracy required, mainly in the resonator frequency response, leads to a digital implementation. In this way, component ageing and thermal fluctuation problems are avoided, as well as the need for manual adjusting. A prototype of the proposed DRL circuit was built and tested in laboratory conditions showing an open-loop gain of 74dB at 50Hz. It was also tested by acquiring real EEG signals.

  13. Linac-driven spallation-neutron source

    SciTech Connect

    Jason, A.J.

    1995-05-01

    Strong interest has arisen in accelerator-driven spallation-neutron sources that surpass existing facilities (such as ISIS at Rutherford or LANSCE at Los Alamos) by more than an order of magnitude in beam power delivered to the spallation target. The approach chosen by Los Alamos (as well as the European Spallation Source) provides the full beam energy by acceleration in a linac as opposed to primary acceleration in a synchrotron or other circular device. Two modes of neutron production are visualized for the source. A short-pulse mode produces 1 MW of beam power (at 60 pps) in pulses, of length less than 1 ms, by compression of the linac macropulse through multi-turn injection in an accumulator ring. A long-pulse mode produces a similar beam power with 1-ms-long pulses directly applied to a target. This latter mode rivals the performance of existing reactor facilities to very low neutron energies. Combination with the short-pulse mode addresses virtually all applications.

  14. Hydrogel Actuation by Electric Field Driven Effects

    NASA Astrophysics Data System (ADS)

    Morales, Daniel Humphrey

    Hydrogels are networks of crosslinked, hydrophilic polymers capable of absorbing and releasing large amounts of water while maintaining their structural integrity. Polyelectrolyte hydrogels are a subset of hydrogels that contain ionizable moieties, which render the network sensitive to the pH and the ionic strength of the media and provide mobile counterions, which impart conductivity. These networks are part of a class of "smart" material systems that can sense and adjust their shape in response to the external environment. Hence, the ability to program and modulate hydrogel shape change has great potential for novel biomaterial and soft robotics applications. We utilized electric field driven effects to manipulate the interaction of ions within polyelectrolyte hydrogels in order to induce controlled deformation and patterning. Additionally, electric fields can be used to promote the interactions of separate gel networks, as modular components, and particle assemblies within gel networks to develop new types of soft composite systems. First, we present and analyze a walking gel actuator comprised of cationic and anionic gel legs attached by electric field-promoted polyion complexation. We characterize the electro-osmotic response of the hydrogels as a function of charge density and external salt concentration. The gel walkers achieve unidirectional motion on flat elastomer substrates and exemplify a simple way to move and manipulate soft matter devices in aqueous solutions. An 'ionoprinting' technique is presented with the capability to topographically structure and actuate hydrated gels in two and three dimensions by locally patterning ions induced by electric fields. The bound charges change the local mechanical properties of the gel to induce relief patterns and evoke localized stress, causing rapid folding in air. The ionically patterned hydrogels exhibit programmable temporal and spatial shape transitions which can be tuned by the duration and/or strength of

  15. Mars: Fluvial Erosion Driven by Magmatism

    NASA Astrophysics Data System (ADS)

    Tanaka, K. L.; Skinner, J. A.; Chapman, M. G.

    2002-12-01

    Mars at present has a thin, dry, and cold atmosphere relative to Earth's. The cold temperatures suggest that any subsurface water (perhaps combined with carbon dioxide as clathrate) would likely be frozen within a couple kilometers or more of the surface. This condition may have been prevalent following widespread fluvial dissection that formed numerous valley networks in highland rocks during the Noachian. The sources of some ancient and of most relatively young valley systems, particularly the large outflow channels, occur within or near volcanic rocks or display morphologic evidence for volcanic and/or tectonic associations. Such geologic relations have led many investigators to propose that magmatic activity has been a significant (if not dominant) driver of younger fluvial erosion on the surface of Mars. Magmatism may have provided the heat to raise local subsurface temperatures to near or above the freezing point of water; furthermore, intrusive activity may have fractured aquifers that provided conduits for release of substantial volumes of ground volatiles. Evidence of such interactions includes lengthy outflow channels sourced from fissures or depressions in volcanic rocks of the Tharsis/Valles Marineris, Elysium, and eastern Hellas regions. Depressions filled with chaotic terrain at the heads of the circum-Chryse outflow channels may be sites where large volumes of magmatic material may have interacted with water and perhaps carbon dioxide in rocks beneath the cryosphere, leading to catastrophic expulsion of the volatiles and collapse of country rock. Other evidence for magmatically driven erosion may include the low Hellas rim areas, where Malea and Hesperia Plana reside, and the channeled flanks of possible Noachian volcanoes in Thaumasia (south Tharsis region). Mars Global Surveyor's MOLA topography data and MOC images and Mars Odyssey's THEMIS images are providing new insights into the possible interactions between magmatism and fluvial erosion on

  16. Pathway-driven discovery of epilepsy genes

    PubMed Central

    Noebels, Jeffrey

    2016-01-01

    Epilepsy genes deliver critical insights into the molecular control of brain synchronization and are revolutionizing our understanding and treatment of the disease. The epilepsy-associated genome is rapidly expanding, and two powerful complementary approaches, isolation of de novo exome variants in patients and targeted mutagenesis in model systems, account for the steep increase. In sheer number, the tally of genes linked to seizures will likely match that of cancer and exceed it in biological diversity. The proteins act within most intracellular compartments and span the molecular determinants of firing and wiring in the developing brain. Every facet of neurotransmission, from dendritic spine to exocytotic machinery, is in play, and defects of synaptic inhibition are over-represented. The contributions of somatic mutations and noncoding microRNAs are also being explored. The functional spectrum of established epilepsy genes and the arrival of rapid, precise technologies for genome editing now provide a robust scaffold to prioritize hypothesis-driven discovery and further populate this genetic proto-map. Although each gene identified offers translational potential to stratify patient care, the complexity of individual variation and covert actions of genetic modifiers may confound single-gene solutions for the clinical disorder. In vivo genetic deconstruction of epileptic networks, ex vivo validation of variant profiles in patient-derived induced pluripotent stem cells, in silico variant modeling and modifier gene discovery, now in their earliest stages, will help clarify individual patterns. Because seizures stand at the crossroads of all neuronal synchronization disorders in the developing and aging brain, the neurobiological analysis of epilepsy-associated genes provides an extraordinary gateway to new insights into higher cortical function. PMID:25710836

  17. The evolution of information-driven safeguards

    SciTech Connect

    Budlong-sylvester, Kory W; Pilat, Joseph F

    2010-10-14

    From the adoption of the Model Additional Protocol and integrated safeguards in the 1990s, to current International Atomic Energy Agency (IAEA) efforts to deal with cases of noncompliance, the question of how the Agency can best utilize all the information available to it remains of great interest and increasing importance. How might the concept of 'information-driven' safeguards (IDS) evolve in the future? The ability of the Agency to identify and resolve anomalies has always been important and has emerged as a core Agency function in recent years as the IAEA has had to deal with noncompliance in Iran and the Democratic People's Republic of Korea (DPRK). Future IAEA safeguards implementation should be designed with the goal of facilitating and enhancing this vital capability. In addition, the Agency should utilize all the information it possesses, including its in-house assessments and expertise, to direct its safeguards activities. At the State level, knowledge of proliferation possibilities is currently being used to guide the analytical activities of the Agency and to develop inspection plans. How far can this approach be extended? Does it apply across State boundaries? Should it dictate a larger fraction of safeguards activities? Future developments in IDS should utilize the knowledge resident within the Agency to ensure that safeguards resources flow to where they are most needed in order to address anomalies first and foremost, but also to provide greater confidence in conclusions regarding the absence of undeclared nuclear activities. The elements of such a system and related implementation issues are assessed in this paper.

  18. Pathway-driven discovery of epilepsy genes.

    PubMed

    Noebels, Jeffrey

    2015-03-01

    Epilepsy genes deliver critical insights into the molecular control of brain synchronization and are revolutionizing our understanding and treatment of the disease. The epilepsy-associated genome is rapidly expanding, and two powerful complementary approaches, isolation of de novo exome variants in patients and targeted mutagenesis in model systems, account for the steep increase. In sheer number, the tally of genes linked to seizures will likely match that of cancer and exceed it in biological diversity. The proteins act within most intracellular compartments and span the molecular determinants of firing and wiring in the developing brain. Every facet of neurotransmission, from dendritic spine to exocytotic machinery, is in play, and defects of synaptic inhibition are over-represented. The contributions of somatic mutations and noncoding microRNAs are also being explored. The functional spectrum of established epilepsy genes and the arrival of rapid, precise technologies for genome editing now provide a robust scaffold to prioritize hypothesis-driven discovery and further populate this genetic proto-map. Although each gene identified offers translational potential to stratify patient care, the complexity of individual variation and covert actions of genetic modifiers may confound single-gene solutions for the clinical disorder. In vivo genetic deconstruction of epileptic networks, ex vivo validation of variant profiles in patient-derived induced pluripotent stem cells, in silico variant modeling and modifier gene discovery, now in their earliest stages, will help clarify individual patterns. Because seizures stand at the crossroads of all neuronal synchronization disorders in the developing and aging brain, the neurobiological analysis of epilepsy-associated genes provides an extraordinary gateway to new insights into higher cortical function. PMID:25710836

  19. Buoyancy Driven Shear Flows of Bubble Suspensions

    NASA Astrophysics Data System (ADS)

    Hill, R. J.; Zenit, R.; Chellppannair, T.; Koch, D. L.; Spelt, P. D. M.; Sangani, A.

    1998-11-01

    In this work the gas volume fraction and the root-mean-squared fluid velocity are measured in buoyancy driven shear flows of bubble suspensions in a tall, inclined, rectangular channel. The experiments are performed under conditions where We << 1 and Re >> 1 , so that the bubbles are relatively undeformed and the flow is inviscid and approximately irrotational. Nitrogen is introduced through an array of capillaries at the base of a .2x.02x2 m channel filled with an aqueous electrolyte solution (0.06 molL-1 MgSO_4). The rising bubbles generate a unidirectional shear flow, where the denser suspension at the lower surface of the channel falls, while the less dense suspension at the upper surface rises. Hot-film anemometry is used to measure the resulting gas volume fraction and fluid velocity profiles. The bubble collision rate with the sensor is related to the gas volume fraction and the mean and variance of the bubble velocity using an experimentally measured collision surface area for the sensor. Bubble collisions with the sensor are identified by the characteristic slope of the hot-film anemometer signal when bubbles collide with the sensor. It is observed that the steady shear flow develops a bubble phase pressure gradient across the channel gap as the bubbles interchange momentum through direct collisions. The discrete phase presssure gradient balances the buoyancy force driving bubbles toward the upper surface resulting in a steady void fraction profile across the gap width. The strength of the shear flow is controlled by the extent of bubble segregation and by the effective viscosity of the bubble phase. The measurements are compared with solutions of the averaged equations of motion (Kang et al. 1997; Spelt and Sangani, 1998), for a range of gas volume fractions and channel inclination angles.

  20. Pathway-driven discovery of epilepsy genes.

    PubMed

    Noebels, Jeffrey

    2015-03-01

    Epilepsy genes deliver critical insights into the molecular control of brain synchronization and are revolutionizing our understanding and treatment of the disease. The epilepsy-associated genome is rapidly expanding, and two powerful complementary approaches, isolation of de novo exome variants in patients and targeted mutagenesis in model systems, account for the steep increase. In sheer number, the tally of genes linked to seizures will likely match that of cancer and exceed it in biological diversity. The proteins act within most intracellular compartments and span the molecular determinants of firing and wiring in the developing brain. Every facet of neurotransmission, from dendritic spine to exocytotic machinery, is in play, and defects of synaptic inhibition are over-represented. The contributions of somatic mutations and noncoding microRNAs are also being explored. The functional spectrum of established epilepsy genes and the arrival of rapid, precise technologies for genome editing now provide a robust scaffold to prioritize hypothesis-driven discovery and further populate this genetic proto-map. Although each gene identified offers translational potential to stratify patient care, the complexity of individual variation and covert actions of genetic modifiers may confound single-gene solutions for the clinical disorder. In vivo genetic deconstruction of epileptic networks, ex vivo validation of variant profiles in patient-derived induced pluripotent stem cells, in silico variant modeling and modifier gene discovery, now in their earliest stages, will help clarify individual patterns. Because seizures stand at the crossroads of all neuronal synchronization disorders in the developing and aging brain, the neurobiological analysis of epilepsy-associated genes provides an extraordinary gateway to new insights into higher cortical function.

  1. Shadow-driven 4D haptic visualization.

    PubMed

    Zhang, Hui; Hanson, Andrew

    2007-01-01

    Just as we can work with two-dimensional floor plans to communicate 3D architectural design, we can exploit reduced-dimension shadows to manipulate the higher-dimensional objects generating the shadows. In particular, by taking advantage of physically reactive 3D shadow-space controllers, we can transform the task of interacting with 4D objects to a new level of physical reality. We begin with a teaching tool that uses 2D knot diagrams to manipulate the geometry of 3D mathematical knots via their projections; our unique 2D haptic interface allows the user to become familiar with sketching, editing, exploration, and manipulation of 3D knots rendered as projected imageson a 2D shadow space. By combining graphics and collision-sensing haptics, we can enhance the 2D shadow-driven editing protocol to successfully leverage 2D pen-and-paper or blackboard skills. Building on the reduced-dimension 2D editing tool for manipulating 3D shapes, we develop the natural analogy to produce a reduced-dimension 3D tool for manipulating 4D shapes. By physically modeling the correct properties of 4D surfaces, their bending forces, and their collisions in the 3D haptic controller interface, we can support full-featured physical exploration of 4D mathematical objects in a manner that is otherwise far beyond the experience accessible to human beings. As far as we are aware, this paper reports the first interactive system with force-feedback that provides "4D haptic visualization" permitting the user to model and interact with 4D cloth-like objects.

  2. Evaporation flows driven by early B stars.

    NASA Astrophysics Data System (ADS)

    Peeters, Els

    2013-10-01

    Young massive OB stars significantly influence their environment as their far-UV photons (6 eV < E < 13.6 eV) dominate the physics and chemistry of the surrounding gas, creating PhotoDissociation Regions (PDRs). The incident FUV field heats and photo-dissociates the PDR and may create evaporation flows of the PDR surfaces. These photo-evaporated flows are fundamental to understanding proplyds, pillars, and the evolution of molecular clouds and hence may greatly influence the star and planet formation process. As the far-UV luminosity of the galaxy is dominated by later type B stars rather than O stars, understanding the interaction of B stars with nearby molecular clouds is key. However, for the majority of the PDRs -- those associated with lower mass B stars -- the photo-evaporation process and its relation with star formation are not well studied. Here, we propose a velocity-resolved study of the [CII] line at 158 micron with the GREAT spectrometer on board of SOFIA to study the dynamical interaction of the B2V star HD 39703 and the B0.5IVe star gamma Cas with the molecular cloud they illuminate. These regions are well-studied over a wide-wavelength range and have been observed by Spitzer/IRS in spectral mapping and Herschel/PACS in both photometry and line-mapping (cooling lines, CO). The goal of this combined SOFIA/Herschel/Spitzer study is to address the kinematic characteristics of the interaction of these two stars with the molecular cloud, determine the mass loss rate, and assess their role in triggering star formation in the PDR. In this way, we can assess the role of evaporation flows driven by early B stars in the evolution of molecular clouds.

  3. Winds driven by the Saharan heat low

    NASA Astrophysics Data System (ADS)

    Dalu, Giovanni; Baldi, Marina; Gaetani, Marco

    2016-04-01

    In this paper we present an analysis of the winds driven by the Saharan heat low (SHL), generated in summer by the sensible heat fluxes over the hot Sahara desert. The SHL is longitudinally as wide as the Sahara desert and seasonally oscillates between 8 degrees north and 25 degrees north, to the west of the Hoggar massif. The SHL is the summer evolution of the West African heat low (WAHL), which is smaller and deeper in winter, and occupies a south-easterly position to the east of the Gulf of Guinea. These lows are important, because they drive the surface and the mid-tropospheric winds. In the mixed layer above the surface, the desert winds have a cyclonic curvature up to 1.5 km in winter and up to 2.5 km in summer. In the free troposphere above the mixed layer, the winds are more intense with a small anticyclonic curvature. The dry north-easterly surface winds to the north of the desert low are known as Harmattan; while the south-westerly surface winds to the south of the desert low carry moisture from the Tropical Atlantic. This moist air converges towards the thermal heat low, where it rises up to the mid-troposphere, and, subsiding to the north of the heat low, generates the Libyan anticyclone. To the south of the desert low, the tropospheric winds are characterized by a strong easterly jet, known as African easterly jet, and it is important for the sub-Sahara region, because it acts as waveguide for the easterly weather perturbations, which bring the rainfall to the Sahel. In addition, about half of the hurricanes, which cross the Tropical Atlantic, are generated by these perturbations.

  4. Beam Ion Driven Instabilities in NSTX

    SciTech Connect

    N.N. Gorelenkov; E. Belova; H.L. Berk; C.Z. Cheng; E. Fredrickson; W. Heidbrink; S. Kaye; G. Kramer

    2003-11-07

    A low-field, low-aspect-ratio device such as NSTX (National Spherical Torus Experiment) is an excellent testbed to study the ITER-relevant physics of fast-particle confinement that is of major importance for burning plasmas. The low Alfvin speed in NSTX offers a window to the super-Alfvinic regime expected in ITER. Effects such as the large FLR, orbit width, strong shaping, and high thermal and fast-ion betas make this effort a greater challenge. We report on the linear stability of different Alfvin eigenmode (AE) branches and compare theory with experimental data. Low-frequency MHD activities, {approx}100 kHz, on NSTX are often observed and identified as the toroidicity-induced AEs (TAE) driven by beam ions. Sometimes they are accompanied by beam ion losses in H-mode, high q(0) plasmas. Numerical analysis using the NOVA-K code shows good agreement with the experimental data. The TAE instability was compared in experiments on NSTX and DIII-D. With very similar plasma conditions, we tested the theoretical prediction that the toroidal mode number of the most unstable TAEs scales with the machine minor radius, n {approx} a. In NSTX, TAEs are observed with n = 1-2, whereas in DIII-D n = 4-7. The confirmation of n scaling validates the predictive capabilities of theoretical tools (NOVA-K) for studying ITER plasmas. In the high-frequency range, recent observations of rich sub-ion cyclotron frequency MHD activities in NSTX suggest that new instabilities are excited, which we identify as Global shear AEs (GAEs). Similar to the compressional AEs (CAEs), GAEs are destabilized by the Doppler-shifted cyclotron resonance in the presence of 80 keV neutral-beam injection. To simulate GAE/CAEs in realistic NSTX plasma conditions, we have developed a nonlinear hybrid kinetic-MHD code, HYM, which is capable of computing the mode structure, saturation, and energetic particle transport.

  5. The service-driven service company.

    PubMed

    Schlesinger, L A; Heskett, J L

    1991-01-01

    For more than 40 years, service companies like McDonald's prospered with organizations designed according to the principles of traditional mass-production manufacturing. Today that model is obsolete. It inevitably degrades the quality of service a company can provide by setting in motion a cycle of failure that produces dissatisfied customers, unhappy employees, high turnover among both--and so lower profits and lower productivity overall. The cycle starts with human resource policies that minimize the contributions frontline workers can make: jobs are designed to be idiot-proof. Technology is used largely for monitoring and control. Pay is poor. Training is minimal. Performance expectations are abysmally low. Today companies like Taco Bell, Dayton Hudson, and ServiceMaster are reversing the cycle of failure by putting workers with customer contact first and designing the business system around them. As a result, they are developing a model that replaces the logic of industrialization with a new service-driven logic. This logic: Values investments in people as much as investments in technology--and sometimes more. Uses technology to support the efforts of workers on the front lines, not just to monitor or replace them. Makes recruitment and training crucial for everyone. Links compensation to performance for employees at every level. To justify these investments, the new logic draws on innovative data such as the incremental profits of loyal customers and the total costs of lost employees. Its benefits are becoming clear in higher profits and higher pay--results that competitors bound to the old industrial model will not be able to match. PMID:10113913

  6. Ontology-driven execution of clinical guidelines.

    PubMed

    Isern, David; Sánchez, David; Moreno, Antonio

    2012-08-01

    Clinical guidelines (CG) contain general descriptions, defined by health care organisations, of the way in which a particular pathology should be treated. Their adoption in daily care offers several benefits to both patients and practitioners, such as the standardisation of the delivered care and the reduction of errors, but, at the same time, there are several issues that limit their application. CGs are designed to cover a disease taking into account the available evidence but are not designed to be deployed in a particular hospital or healthcare institution. CGs include general recommendations that should be translated according the particular settings before adoption in daily care. This adoption should also specify accountable information about the responsible actors of performing actions in healthcare teams in order to avoid errors arising during delegation/assignment of tasks. In addition, this enactment is not performed taking into account a central knowledge base or a single actor. This paper proposes the combination of a multi-agent system modelling complex healthcare organisations and knowledge representation techniques in order to build a general framework for enabling the enactment of CGs in the context of a medical centre. As a main contribution, the ontological paradigm and the expressiveness of modern ontology languages are used to design, implement and exploit a medico-organisational ontology aimed to provide the semantics required to support the execution of clinical guidelines. The knowledge-driven guideline enactment is managed by a multi-agent system modelling in a distributed fashion the clinical entities involved in the care delivery.

  7. Ecology-driven stereotypes override race stereotypes

    PubMed Central

    Williams, Keelah E. G.; Sng, Oliver; Neuberg, Steven L.

    2016-01-01

    Why do race stereotypes take the forms they do? Life history theory posits that features of the ecology shape individuals’ behavior. Harsh and unpredictable (“desperate”) ecologies induce fast strategy behaviors such as impulsivity, whereas resource-sufficient and predictable (“hopeful”) ecologies induce slow strategy behaviors such as future focus. We suggest that individuals possess a lay understanding of ecology’s influence on behavior, resulting in ecology-driven stereotypes. Importantly, because race is confounded with ecology in the United States, we propose that Americans’ stereotypes about racial groups actually reflect stereotypes about these groups’ presumed home ecologies. Study 1 demonstrates that individuals hold ecology stereotypes, stereotyping people from desperate ecologies as possessing faster life history strategies than people from hopeful ecologies. Studies 2–4 rule out alternative explanations for those findings. Study 5, which independently manipulates race and ecology information, demonstrates that when provided with information about a person’s race (but not ecology), individuals’ inferences about blacks track stereotypes of people from desperate ecologies, and individuals’ inferences about whites track stereotypes of people from hopeful ecologies. However, when provided with information about both the race and ecology of others, individuals’ inferences reflect the targets’ ecology rather than their race: black and white targets from desperate ecologies are stereotyped as equally fast life history strategists, whereas black and white targets from hopeful ecologies are stereotyped as equally slow life history strategists. These findings suggest that the content of several predominant race stereotypes may not reflect race, per se, but rather inferences about how one’s ecology influences behavior. PMID:26712013

  8. OSCILLATION-DRIVEN MAGNETOSPHERIC ACTIVITY IN PULSARS

    SciTech Connect

    Lin, Meng-Xiang; Xu, Ren-Xin; Zhang, Bing E-mail: r.x.xu@pku.edu.cn

    2015-02-01

    We study the magnetospheric activity in the polar cap region of pulsars under stellar oscillations. The toroidal oscillation of the star propagates into the magnetosphere, which provides additional voltage due to unipolar induction, changes Goldreich-Julian charge density from the traditional value due to rotation, and hence influences particle acceleration. We present a general solution of the effect of oscillations within the framework of the inner vacuum gap model and consider three different inner gap modes controlled by curvature radiation, inverse Compton scattering, and two-photon annihilation, respectively. With different pulsar parameters and oscillation amplitudes, one of three modes would play a dominant role in defining the gap properties. When the amplitude of oscillation exceeds a critical value, mode changing occurs. Oscillations also lead to a change of the size of the polar cap. As applications, we show the inner gap properties under oscillations in both normal pulsars and anomalous X-ray pulsars/soft gamma-ray repeaters (AXPs/SGRs). We interpret the onset of radio emission after glitches/flares in AXPs/SGRs as due to oscillation-driven magnetic activities in these objects, within the framework of both the magnetar model and the solid quark star model. Within the magnetar model, radio activation may be caused by the enlargement of the effective polar cap angle and the radio emission beam due to oscillation, whereas within the solid quark star angle, it may be caused by activation of the pulsar inner gap from below the radio emission death line due to an oscillation-induced voltage enhancement. The model can also explain the glitch-induced radio profile change observed in PSR J1119–6127.

  9. 76 FR 3604 - Information Collection; Qualified Products List for Engine Driven Pumps

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-20

    ... Forest Service Information Collection; Qualified Products List for Engine Driven Pumps AGENCY: Forest... on the new information collection, Qualified Products List for Engine Driven Pumps. DATES: Comments.... SUPPLEMENTARY INFORMATION: Title: Qualified Products List for Engine Driven Pumps. OMB Number:...

  10. Comparison between kinetic-ballooning-mode-driven turbulence and ion-temperature-gradient-driven turbulence

    SciTech Connect

    Maeyama, S. Nakata, M.; Miyato, N.; Yagi, M.; Ishizawa, A.; Watanabe, T.-H.; Idomura, Y.

    2014-05-15

    Electromagnetic turbulence driven by kinetic ballooning modes (KBMs) in high-β plasma is investigated based on the local gyrokinetic model. Analysis of turbulent fluxes, norms, and phases of fluctuations shows that KBM turbulence gives narrower spectra and smaller phase factors than those in ion-temperature-gradient (ITG)-driven turbulence. This leads to the smaller transport fluxes in KBM turbulence than those in ITG turbulence even when they have similar linear growth rates. From the analysis of the entropy balance relation, it is found that the entropy transfer from ions to electrons through the field-particle interactions mainly drives electron perturbations, which creates radial twisted modes by rapid parallel motions of electrons in a sheared magnetic geometry. The nonlinear coupling between the dominant unstable mode and its twisted modes is important for the saturation of KBM turbulence, in contrast to the importance of zonal flow shearing in ITG turbulence. The coupling depends on the flux-tube domain with the one-poloidal-turn parallel length and on the torus periodicity constraint.

  11. Combining Environment-Driven Adaptation and Task-Driven Optimisation in Evolutionary Robotics

    PubMed Central

    Haasdijk, Evert; Bredeche, Nicolas; Eiben, A. E.

    2014-01-01

    Embodied evolutionary robotics is a sub-field of evolutionary robotics that employs evolutionary algorithms on the robotic hardware itself, during the operational period, i.e., in an on-line fashion. This enables robotic systems that continuously adapt, and are therefore capable of (re-)adjusting themselves to previously unknown or dynamically changing conditions autonomously, without human oversight. This paper addresses one of the major challenges that such systems face, viz. that the robots must satisfy two sets of requirements. Firstly, they must continue to operate reliably in their environment (viability), and secondly they must competently perform user-specified tasks (usefulness). The solution we propose exploits the fact that evolutionary methods have two basic selection mechanisms–survivor selection and parent selection. This allows evolution to tackle the two sets of requirements separately: survivor selection is driven by the environment and parent selection is based on task-performance. This idea is elaborated in the Multi-Objective aNd open-Ended Evolution (monee) framework, which we experimentally validate. Experiments with robotic swarms of 100 simulated e-pucks show that monee does indeed promote task-driven behaviour without compromising environmental adaptation. We also investigate an extension of the parent selection process with a ‘market mechanism’ that can ensure equitable distribution of effort over multiple tasks, a particularly pressing issue if the environment promotes specialisation in single tasks. PMID:24901702

  12. Flow-driven waves and sink-driven oscillations during aggregation of Dictyostelium discoideum

    NASA Astrophysics Data System (ADS)

    Gholami, Azam; Zykov, Vladimir; Steinbock, Oliver; Bodenschatz, Eberhard

    The slime mold Dictyostelium discoideum (D.d) is a well-known model system for the study of biological pattern formation. Under starvation, D.d. cells aggregate chemotactically towards cAMP signals emitted periodically from an aggregation center. In the natural environment, D.d cells may experience fluid flows that can profoundly change the underlying wave generation process. We investigate spatial-temporal dynamics of a uniformly distributed population of D.d. cells in a flow-through narrow microfluidic channel with a cell-free inlet area. We show that flow can significantly influence the dynamics of the system and lead to a flow- driven instability that initiate downstream traveling cAMP waves. We also show that cell-free boundary regions have a significant effect on the observed patterns and can lead to a new kind of instability. Since there are no cells in the inlet to produce cAMP, the points in the vicinity of the inlet lose cAMP due to advection or diffusion and gain only a little from the upstream of the channel (inlet). In other words, there is a large negative flux of cAMP in the neighborhood close to the inlet, which can be considered as a sink. This negative flux close to the inlet drives a new kind of instability called sink-driven oscillations. Financial support of the MaxSynBio Consortium is acknowledged.

  13. Developing a theory driven text messaging intervention for addiction care with user driven content.

    PubMed

    Muench, Frederick; Weiss, Rebecca A; Kuerbis, Alexis; Morgenstern, Jon

    2013-03-01

    The number of text messaging interventions designed to initiate and support behavioral health changes have been steadily increasing over the past 5 years. Messaging interventions can be tailored and adapted to an individual's needs in their natural environment-fostering just-in-time therapies and making them a logical intervention for addiction continuing care. This study assessed the acceptability of using text messaging for substance abuse continuing care and the intervention preferences of individuals in substance abuse treatment in order to develop an interactive mobile text messaging intervention. Fifty individuals enrolled in intensive outpatient substance abuse treatment completed an assessment battery relating to preferred logistics of mobile interventions, behavior change strategies, and types of messages they thought would be most helpful to them at different time points. Results indicated that 98% participants were potentially interested in using text messaging as a continuing care strategy. Participants wrote different types of messages that they perceived might be most helpful, based on various hypothetical situations often encountered during the recovery process. Although individuals tended to prefer benefit driven over consequence driven messages, differences in the perceived benefits of change among individuals predicted message preference. Implications for the development of mobile messaging interventions for the addictions are discussed. (PsycINFO Database Record (c) 2013 APA, all rights reserved).

  14. Combining environment-driven adaptation and task-driven optimisation in evolutionary robotics.

    PubMed

    Haasdijk, Evert; Bredeche, Nicolas; Eiben, A E

    2014-01-01

    Embodied evolutionary robotics is a sub-field of evolutionary robotics that employs evolutionary algorithms on the robotic hardware itself, during the operational period, i.e., in an on-line fashion. This enables robotic systems that continuously adapt, and are therefore capable of (re-)adjusting themselves to previously unknown or dynamically changing conditions autonomously, without human oversight. This paper addresses one of the major challenges that such systems face, viz. that the robots must satisfy two sets of requirements. Firstly, they must continue to operate reliably in their environment (viability), and secondly they must competently perform user-specified tasks (usefulness). The solution we propose exploits the fact that evolutionary methods have two basic selection mechanisms-survivor selection and parent selection. This allows evolution to tackle the two sets of requirements separately: survivor selection is driven by the environment and parent selection is based on task-performance. This idea is elaborated in the Multi-Objective aNd open-Ended Evolution (monee) framework, which we experimentally validate. Experiments with robotic swarms of 100 simulated e-pucks show that monee does indeed promote task-driven behaviour without compromising environmental adaptation. We also investigate an extension of the parent selection process with a 'market mechanism' that can ensure equitable distribution of effort over multiple tasks, a particularly pressing issue if the environment promotes specialisation in single tasks.

  15. Silver decorated titanate/titania nanostructures for efficient solar driven photocatalysis

    SciTech Connect

    Gong, Dangguo; Ho, Weng Chye Jeffrey; Tang Yuxin; Tay Qiuling; Lai Yuekun; Highfield, James George; Chen Zhong

    2012-05-15

    Photocatalysis has attracted significant interest to solve both the energy crisis and effectively combat environmental contamination. However, as the most widely used photocatalyst, titania (TiO{sub 2}) suffers from inefficient utilization of solar energy due to its wide band gap. In the present paper, we describe a method to extend the absorption edge of photocatalyst to visible region by the surface plasmon effect of silver. Silver ions are photo-reduced onto the surface of titanate nanotubes, which are synthesized by a conventional hydrothermal method. The as-synthesized Ag/titanate composite is transformed into Ag/titania nanoparticles by annealing at different temperatures. It is found that the interaction of Ag nanoparticles with the supports (titanate/titania) plays a key role for the visible light activity. The samples annealed at low temperature (<350 Degree-Sign C) do not show significant activity under our conditions, while the one annealed at 450 Degree-Sign C shows fast-degradation of methyl orange (MO) under visible light irradiation. The detailed mechanisms are also discussed. - Graphical abstract: Silver nanoparticles decorated titanate/titania as visible light active photocatalysts: silver nanoparticles could be excited by visible light due to its surface plasmon effect and excited electrons could be transferred to the conduction band of the semiconductor, where the reduction process occurs. Highlights: Black-Right-Pointing-Pointer Uniform Ag nanoparticles are photo-reduced onto titanate and titania nanostructures. Black-Right-Pointing-Pointer Titania crystal is formed by annealing hydrogen titanate at different temperatures. Black-Right-Pointing-Pointer Best visible-light activity is achieved by Ag-loaded titania annealed at 450 Degree-Sign C. Black-Right-Pointing-Pointer The visible light activity is attributed to the surface plasmonic resonance effect.

  16. Theoretical and experimental analysis of an optical driven servo system

    NASA Astrophysics Data System (ADS)

    Lu, F.; Wang, X. J.; Huang, J. H.; Liu, Y. F.

    2016-09-01

    An optical driven servo system model based on single-type PLZT ceramic is proposed in this paper. The control equation of the proposed servo system is derived based on the mathematical model of PLZT with coupled multi-physics fields. The parameters of photodeformation of the PLZT actuator during both the illumination phase and light off phase are identified through the static experiment. Then displacement response of optical driven servo system is numerically simulated based on the control equation presented in this paper. After that, the closed-loop control experiment of optical driven servo system based on PLZT single-type ceramic with a simple on-off method is carried out. The experimental results show that the optical driven servo system with simple on-off method can achieve the target displacement by applying UV light to the PLZT actuator. Furthermore, an improved on-off control strategy is proposed to decrease the undesirable fluctuation around the target displacement.

  17. Coalescence cascade of dissipative solitons in parametrically driven systems.

    PubMed

    Clerc, M G; Coulibaly, S; Gordillo, L; Mujica, N; Navarro, R

    2011-09-01

    Parametrically driven spatially extended systems exhibit uniform oscillations which are modulationally unstable. The resulting periodic state evolves to the creation of a gas of dissipative solitons. Driven by the interaction of dissipative solitons, the multisoliton state undergoes a cascade of coalescence processes, where the average soliton separation distance obeys a temporal self-similar law. Starting from the soliton pair interaction law, we have derived analytically and characterized the law of this multisoliton coarsening process. A comparison of numerical results obtained with different models such as the parametrically driven damped nonlinear Schrödinger equation, a vertically driven chain of pendula, and a parametrically forced magnetic wire, shows remarkable agreement. Both phenomena, the pair interaction law and the coarsening process, are also observed experimentally in a quasi-one-dimensional layer of Newtonian fluid which is oscillated vertically. PMID:22060473

  18. Plasmon-driven sequential chemical reactions in an aqueous environment

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Wang, Peijie; Zhang, Zhenglong; Fang, Yurui; Sun, Mengtao

    2014-06-01

    Plasmon-driven sequential chemical reactions were successfully realized in an aqueous environment. In an electrochemical environment, sequential chemical reactions were driven by an applied potential and laser irradiation. Furthermore, the rate of the chemical reaction was controlled via pH, which provides indirect evidence that the hot electrons generated from plasmon decay play an important role in plasmon-driven chemical reactions. In acidic conditions, the hot electrons were captured by the abundant H+ in the aqueous environment, which prevented the chemical reaction. The developed plasmon-driven chemical reactions in an aqueous environment will significantly expand the applications of plasmon chemistry and may provide a promising avenue for green chemistry using plasmon catalysis in aqueous environments under irradiation by sunlight.

  19. Recent advances in laser-driven neutron sources

    NASA Astrophysics Data System (ADS)

    Alejo, A.; Ahmed, H.; Green, A.; Mirfayzi, S. R.; Borghesi, M.; Kar, S.

    2016-11-01

    Due to the limited number and high cost of large-scale neutron facilities, there has been a growing interest in compact accelerator-driven sources. In this context, several potential schemes of laser-driven neutron sources are being intensively studied employing laser-accelerated electron and ion beams. In addition to the potential of delivering neutron beams with high brilliance, directionality and ultra-short burst duration, a laser-driven neutron source would offer further advantages in terms of cost-effectiveness, compactness and radiation confinement by closed-coupled experiments. Some of the recent advances in this field are discussed, showing improvements in the directionality and flux of the laser-driven neutron beams.

  20. Plasmon-driven sequential chemical reactions in an aqueous environment.

    PubMed

    Zhang, Xin; Wang, Peijie; Zhang, Zhenglong; Fang, Yurui; Sun, Mengtao

    2014-06-24

    Plasmon-driven sequential chemical reactions were successfully realized in an aqueous environment. In an electrochemical environment, sequential chemical reactions were driven by an applied potential and laser irradiation. Furthermore, the rate of the chemical reaction was controlled via pH, which provides indirect evidence that the hot electrons generated from plasmon decay play an important role in plasmon-driven chemical reactions. In acidic conditions, the hot electrons were captured by the abundant H(+) in the aqueous environment, which prevented the chemical reaction. The developed plasmon-driven chemical reactions in an aqueous environment will significantly expand the applications of plasmon chemistry and may provide a promising avenue for green chemistry using plasmon catalysis in aqueous environments under irradiation by sunlight.

  1. Theoretical and experimental analysis of an optical driven servo system

    NASA Astrophysics Data System (ADS)

    Lu, F.; Wang, X. J.; Huang, J. H.; Liu, Y. F.

    2016-09-01

    An optical driven servo system model based on single-type PLZT ceramic is proposed in this paper. The control equation of the proposed servo system is derived based on the mathematical model of PLZT with coupled multi-physics fields. The parameters of photodeformation of the PLZT actuator during both the illumination phase and light off phase are identified through the static experiment. Then displacement response of optical driven servo system is numerically simulated based on the control equation presented in this paper. After that, the closed-loop control experiment of optical driven servo system based on PLZT single-type ceramic with a simple on–off method is carried out. The experimental results show that the optical driven servo system with simple on–off method can achieve the target displacement by applying UV light to the PLZT actuator. Furthermore, an improved on–off control strategy is proposed to decrease the undesirable fluctuation around the target displacement.

  2. Plasmon-driven sequential chemical reactions in an aqueous environment

    PubMed Central

    Zhang, Xin; Wang, Peijie; Zhang, Zhenglong; Fang, Yurui; Sun, Mengtao

    2014-01-01

    Plasmon-driven sequential chemical reactions were successfully realized in an aqueous environment. In an electrochemical environment, sequential chemical reactions were driven by an applied potential and laser irradiation. Furthermore, the rate of the chemical reaction was controlled via pH, which provides indirect evidence that the hot electrons generated from plasmon decay play an important role in plasmon-driven chemical reactions. In acidic conditions, the hot electrons were captured by the abundant H+ in the aqueous environment, which prevented the chemical reaction. The developed plasmon-driven chemical reactions in an aqueous environment will significantly expand the applications of plasmon chemistry and may provide a promising avenue for green chemistry using plasmon catalysis in aqueous environments under irradiation by sunlight. PMID:24958029

  3. Space Coffee Cup: Capillary Flow Driven Fluids in Space

    NASA Video Gallery

    Interested in learning more about how fluids react in Space? In this video, Professor Mark Weislogel, and Dr. Marshall Porterfield will discuss the Space Coffee Cup and Capillary Flow Driven Fluids...

  4. Event-Driven Process Chains (EPC)

    NASA Astrophysics Data System (ADS)

    Mendling, Jan

    This chapter provides a comprehensive overview of Event-driven Process Chains (EPCs) and introduces a novel definition of EPC semantics. EPCs became popular in the 1990s as a conceptual business process modeling language in the context of reference modeling. Reference modeling refers to the documentation of generic business operations in a model such as service processes in the telecommunications sector, for example. It is claimed that reference models can be reused and adapted as best-practice recommendations in individual companies (see [230, 168, 229, 131, 400, 401, 446, 127, 362, 126]). The roots of reference modeling can be traced back to the Kölner Integrationsmodell (KIM) [146, 147] that was developed in the 1960s and 1970s. In the 1990s, the Institute of Information Systems (IWi) in Saarbrücken worked on a project with SAP to define a suitable business process modeling language to document the processes of the SAP R/3 enterprise resource planning system. There were two results from this joint effort: the definition of EPCs [210] and the documentation of the SAP system in the SAP Reference Model (see [92, 211]). The extensive database of this reference model contains almost 10,000 sub-models: 604 of them non-trivial EPC business process models. The SAP Reference model had a huge impact with several researchers referring to it in their publications (see [473, 235, 127, 362, 281, 427, 415]) as well as motivating the creation of EPC reference models in further domains including computer integrated manufacturing [377, 379], logistics [229] or retail [52]. The wide-spread application of EPCs in business process modeling theory and practice is supported by their coverage in seminal text books for business process management and information systems in general (see [378, 380, 49, 384, 167, 240]). EPCs are frequently used in practice due to a high user acceptance [376] and extensive tool support. Some examples of tools that support EPCs are ARIS Toolset by IDS

  5. Supernovae and AGN Driven Galactic Outflows

    NASA Astrophysics Data System (ADS)

    Sharma, Mahavir; Nath, Biman B.

    2013-01-01

    We present analytical solutions for winds from galaxies with a Navarro-Frank-White (NFW) dark matter halo. We consider winds driven by energy and mass injection from multiple supernovae (SNe), as well as momentum injection due to radiation from a central black hole. We find that the wind dynamics depends on three velocity scales: (1) v_\\star ˜ (\\dot{E} / 2 \\dot{M})^{1/2} describes the effect of starburst activity, with \\dot{E} and \\dot{M} as energy and mass injection rate in a central region of radius R; (2) v • ~ (GM •/2R)1/2 for the effect of a central black hole of mass M • on gas at distance R; and (3) v_{s} =(GM_h / 2 {C}r_s)^{1/2}, which is closely related to the circular speed (vc ) for an NFW halo, where rs is the halo scale radius and {C} is a function of the halo concentration parameter. Our generalized formalism, in which we treat both energy and momentum injection from starbursts and radiation from the central active galactic nucleus (AGN), allows us to estimate the wind terminal speed to be (4v 2 sstarf + 6(Γ - 1)v • 2 - 4v 2 s )1/2, where Γ is the ratio of force due to radiation pressure to gravity of the central black hole. Our dynamical model also predicts the following: (1) winds from quiescent star-forming galaxies cannot escape from 1011.5 M ⊙ <= Mh <= 1012.5 M ⊙ galaxies; (2) circumgalactic gas at large distances from galaxies should be present for galaxies in this mass range; (3) for an escaping wind, the wind speed in low- to intermediate-mass galaxies is ~400-1000 km s-1, consistent with observed X-ray temperatures; and (4) winds from massive galaxies with AGNs at Eddington limit have speeds >~ 1000 km s-1. We also find that the ratio [2v 2 sstarf - (1 - Γ)v • 2]/v 2 c dictates the amount of gas lost through winds. Used in conjunction with an appropriate relation between M • and Mh and an appropriate opacity of dust grains in infrared (K band), this ratio has the attractive property of being minimum at a certain halo

  6. Crawling of a driven adherent membrane

    NASA Astrophysics Data System (ADS)

    Baumgaertner, A.

    2012-10-01

    We discuss motions of an elastic N × M membrane model whose constituents can bind reversibly with strength ɛ to adhesive sites of a flat substrate. One of the edges of the membrane ("front") is driven in one direction at rate constant p by N stochastically treadmilling short parallel lines ("cortex"). The main conclusions derived from Monte Carlo studies of this model are the following: (a) Since the polymerizing cortex pushes only the leading edge of the membrane, the major part of the membranes is dragged behind. Therefore, the locomotion of the membrane can be described by frictional sliding processes which are asymmetrically distributed between front and rear of the membrane. A signature of this asymmetry is the difference between the life times of adhesion bonds at front and rear, τ1 and τM, respectively, where τ1 ≫ τM. (b) There are four characteristic times for the membrane motion: The first time, T0 ˜ τM ˜ eaɛ, is the resting time where the displacement of the membrane is practically zero. The second time, Tp ˜ τ1 ˜ M, is the friction time which characterizes the time between two consecutive ruptures of adhesion bonds at the front, and which signalizes the onset of drift ("protrusion") at the leading edge. The third time, Tr ˜ Mγ(ɛ) (γ > 1), characterizes the "retraction" of the trailing edge, which is the retarded response to the pulling leading edge. The fourth time, TL ˜ M2, is the growth time for fluctuation of the end-to-end distance. (c) The separation of time scales, Tr/Tp ˜ Mγ(ɛ) - 1, leads to stretched fluctuations of the end-to-end distance, which are considered as stochastic cycles of protrusion and retraction on the time scale of TL. (d) The drift velocity v obeys anomalous scaling, {v} / p ˜ f(p^{1/γ (\\varepsilon )}M), where f (z) ˜ const. for small drag pM ≪ 1, and f (z) ˜ z-γ(ɛ) for pM ≫ 1, which implies {v} ˜ M^{-γ (\\varepsilon )}. These results may also turn out to be useful for the (more difficult

  7. Radiolytic Gas-Driven Cryovolcanism at Europa

    NASA Astrophysics Data System (ADS)

    Killen, R. M.; Cooper, J. F.; Sarantos, M.; Sittler, E. C., Jr.

    2014-12-01

    A large apparent plume of water vapor was detected at the south pole of Europa in December 2012 by the Hubble Space Telescope [Roth et al., 2014] when Europa was near maximum radial distance (apojove) in its orbit around Jupiter. The absence thus far of further detections both at apojove and elsewhere may indicate an episodic source. There was reportedly no evident brightening locally or globally of the Europa oxygen neutral atmosphere coincident with the plume water vapor detection. This could be consistent with an O2-driven cryovolcanism model in which bubbles of trapped gases in the ice crust are released from clathrates on thermal contact with rising oceanic water and expand to force upward fluid flows to the surface. It has long been suggested [Chyba, 2000; Cooper et al., 2001] that the Europa ocean could be oxygenated by radiolytic oxygen from surface irradiation, also implying that the overlying ice crust could be saturated in oxygen clathrates [Hand et al., 2006]. That the moon ocean could be a potentially habitable environment by oxygenation or other processes has been a major motivation for missions to Europa. The radiolytic gas source would be far greater at Europa as compared to much lesser source rates for a similar model at Enceladus [Cooper et al., 2009]. Detected plume emissions could arise from both the directly ejected vapor and from sputtering and/or sublimation of chemically-active plume frost in the polar cap region. Europa's surface gravity is much higher than that of Enceladus, so most of the plume vapor would return to the surface as frost. If sputtering or radiolysis were active contributors to polar cap emissions from the frost, then emissions could also maximize at 6.5-hour intervals as Europa passes through the densest part of the jovian magnetospheric plasma sheet as well as at 85-hour apojove intervals of the orbital period. For comparison to available polar cap plume and global atmospheric observations we present ballistic simulations

  8. A Cosmology with a Gravity Driven Inflation

    NASA Astrophysics Data System (ADS)

    Enginol, Turan B.

    2015-08-01

    The theoretically expected value of Λ is some 10120 orders of magnitude larger than the current observational limits. Since Λ=8πc-2ρΛG, where the vacuum energy density ρΛ is constant, we argue that this discrepancy is due to a large value of G at the beginning which decreases to its present value at reheating. This suggests that initially gravity may have been a strong force. Inflation would then be driven by a large Gi, the variation range of G being similar to Λ. This may be a possible solution for the cosmological constant problem.A graceful exit from inflation occurs when ρr reaches the value ρΛ as radiation is created. Radiation is created through the decay of massive particle species φ with small mean lifetimes τ, which are produced by the fluctuations of the gravity field. We find that radiation energy density ρr increases sharply from the end of inflation at Rf to its maximum value and then decreases as R-3/2 until reheating at t=τ, continuing on to decrease with its natural pattern of R-4.Following Sciama's idea of gravitational induction, an equation of continuity for a possibly non-constant G is obtained using the equations of general relativity. This equation indicates that G is non-constant if radiation and/or matter is created, its solution for G having an inverse dependence on the sum of ρr, ρm, and ρΛ. Accordingly, with the sudden increase of ρr, G and therefore Λ fall off sharply from their values Gi and Λi at Rf, and continue to decrease as R-3/2. From reheating on they attain their constant values of the present epoch, namely G0 and Λ0.Our equation of cosmology, obtained by integrating the expression for the deceleration parameter q, gives two inflection points for R=R(t). The first one occurs at the recovery from inflation when ρr(R)=ρΛ. The second inflection is at R’, where R’

  9. Entropic Fluctuations in Thermally Driven Harmonic Networks

    NASA Astrophysics Data System (ADS)

    Jakšić, V.; Pillet, C.-A.; Shirikyan, A.

    2016-10-01

    We consider a general network of harmonic oscillators driven out of thermal equilibrium by coupling to several heat reservoirs at different temperatures. The action of the reservoirs is implemented by Langevin forces. Assuming the existence and uniqueness of the steady state of the resulting process, we construct a canonical entropy production functional S^t which satisfies the Gallavotti-Cohen fluctuation theorem. More precisely, we prove that there exists κ_c>1/2 such that the cumulant generating function of S^t has a large-time limit e(&alpha) which is finite on a closed interval [1/2-κ_c,1/2+κ_c] , infinite on its complement and satisfies the Gallavotti-Cohen symmetry e(1-&alpha)=e(&alpha) for all α in R. Moreover, we show that e(&alpha) is essentially smooth, i.e., that e'(&alpha)→ ∓ ∞ as α → {1}/{2}∓ κ_c . It follows from the Gärtner-Ellis theorem that S^t satisfies a global large deviation principle with a rate function I(s) obeying the Gallavotti-Cohen fluctuation relation I(-s)-I(s)=s for all sin R. We also consider perturbations of S^t by quadratic boundary terms and prove that they satisfy extended fluctuation relations, i.e., a global large deviation principle with a rate function that typically differs from I(s) outside a finite interval. This applies to various physically relevant functionals and, in particular, to the heat dissipation rate of the network. Our approach relies on the properties of the maximal solution of a one-parameter family of algebraic matrix Riccati equations. It turns out that the limiting cumulant generating functions of S^t and its perturbations can be computed in terms of spectral data of a Hamiltonian matrix depending on the harmonic potential of the network and the parameters of the Langevin reservoirs. This approach is well adapted to both analytical and numerical investigations.

  10. Modeling of magnetic field driven simultaneous assembly

    NASA Astrophysics Data System (ADS)

    Rivero, Rene David

    The Magnetic Field Driven Simultaneous Assembly (MFDSA) is a method that offers a non-statistical and deterministic solution to the problem of assembly via batch processing; a hybrid of serial and parallel processing. The technique requires the use of electromagnets as well as soft and hard magnetic materials that are applied to devices and recesses respectively. The MFDSA approach offers the ability to check and correct errors in real-time and is capable of scalable, versatile, and high-yield integration. Devices, coated with a layer of soft magnetic material, are moved from initial to final positions along predetermined pathways through the action of an array of electromagnets. Various devices, of arbitrary geometries, with different physical and functional properties, are manipulated simultaneously toward specific desired locations and then dropped onto a template under the influence of gravity by weakening the local applied field. Locations on the template correspond to sites on a substrate that contain recesses. When a number of devices have been dropped onto the template, a substrate is pressed onto it and the soft magnetic layers on the devices adhere to the hard magnetic strips in the recesses, completing integration in a single step. The objectives of this dissertation are the following: to present the MFDSA method; comparing and contrasting it with other extant techniques employed by the semiconductor industry; to discuss key aspects of this solution with respect to the problem of assembly, and to model the calculations involved with determining both device pathways and field interactions that are required to implement the approach. The Fourier Series technique will be used to describe the force of attraction between the device's soft magnetic layer and the recess's hard magnetic strips. Methodology from finite element analysis will be employed to calculate the force exerted on a device by an array of electromagnets. The Swarm Algorithm, which was

  11. Buoyancy Driven Shear Flows of Bubble Suspensions

    NASA Technical Reports Server (NTRS)

    Koch, D. L.; Hill, R. J.; Chellppannair, T.; Zenit, R.; Zenit, R.; Spelt, P. D. M.

    1999-01-01

    In this work the gas volume fraction and the root-mean-squared fluid velocity are measured in buoyancy driven shear flows of bubble suspensions in a tall, inclined, rectangular channel. The experiments are performed under conditions where We << 1a nd Re >> 1, for which comparisons are made with kinetic theory and numerical simulations. Here Re = gamma(a(exp 2)/nu is the Reynolds number and We = rho(gamma(exp 2))a(exp 3)/sigma is the Weber number; gamma is the shear rate, a is the bubble radius, nu is the kinematic viscosity of the liquid, rho is the density of the liquid, and sigma is the surface tension of the gas/liquid interface. Kang et al. calculated the bubble phase pressure and velocity variance of sheared bubble suspensions under conditions where the bubbles are spherical and the liquid phase velocity field can be approximated using potential flow theory, i.e. We= 0 and Re >> 1. Such conditions can be achieved in an experiment using gas bubbles, with a radius of O(0.5mm), in water. The theory requires that there be no average relative motion of the gas and liquid phases, hence the motivation for an experimental program in microgravity. The necessity of performing preliminary, Earth based experiments, however, requires performing experiments where the gas phase rises in the liquid, which significantly complicates the comparison of experiments with theory. Rather than comparing experimental results with theory for a uniform, homogeneous shear flow, experiments can be compared directly with solutions of the averaged equations of motion for bubble suspensions. This requires accounting for the significant lift force acting on the gas phase when the bubbles rise parallel to the average velocity of the sheared suspension. Shear flows can be produced in which the bubble phase pressure gradient, arising from shear induced collisions amongst the bubbles, balances a body force (centrifugal or gravitational) on the gas phase. A steady, non-uniform gas volume fraction

  12. High Performance Visualization using Query-Driven Visualizationand Analytics

    SciTech Connect

    Bethel, E. Wes; Campbell, Scott; Dart, Eli; Shalf, John; Stockinger, Kurt; Wu, Kesheng

    2006-06-15

    Query-driven visualization and analytics is a unique approach for high-performance visualization that offers new capabilities for knowledge discovery and hypothesis testing. The new capabilities akin to finding needles in haystacks are the result of combining technologies from the fields of scientific visualization and scientific data management. This approach is crucial for rapid data analysis and visualization in the petascale regime. This article describes how query-driven visualization is applied to a hero-sized network traffic analysis problem.

  13. Value-Driven Health Care: The purchaser perspective

    PubMed Central

    Carlos, Ruth C.

    2008-01-01

    Summary The four cornerstones of value-driven health care are health information technology standards, quality standards, price standards and incentives. Value-driven health care seeks to directly link quality health care to reimbursement. The four cornerstones of this movement are health information technology standards, quality standards, price standards and incentives. These standards and the how purchasers plan to implement them are summarized. PMID:18514951

  14. Sequence complementarity-driven nonenzymatic ligation of RNA.

    PubMed

    Pino, Samanta; Costanzo, Giovanna; Giorgi, Alessandra; Di Mauro, Ernesto

    2011-04-12

    We report two reactions of RNA G:C sequences occurring nonenzymatically in water in the absence of any added cofactor or metal ion: (a) sequence complementarity-driven terminal ligation and (b) complementary sequence adaptor-driven multiple tandemization. The two abiotic reactions increase the chemical complexity of the resulting pool of RNA molecules and change the Shannon information of the initial population of sequences.

  15. Climate-Driven Bedrock Incision in an Active Mountain Belt

    NASA Astrophysics Data System (ADS)

    Hartshorn, Karen; Hovius, Niels; Dade, W. Brian; Slingerland, Rudy L.

    2002-09-01

    Measurements of fluvial bedrock incision were made with submillimeter precision in the East Central Range of Taiwan, where long-term exhumation rates and precipitation-driven river discharge are independently known. They indicate that valley lowering is driven by relatively frequent flows of moderate intensity, abrasion by suspended sediment is an important fluvial wear process, and channel bed geometry and the presence of widely spaced planes of weakness in the rock mass influence erosion rate and style.

  16. Dynamics of Lane Formation in Driven Binary Complex Plasmas

    SciTech Connect

    Suetterlin, K. R.; Ivlev, A. V.; Raeth, C.; Thomas, H. M.; Rubin-Zuzic, M.; Morfill, G. E.; Wysocki, A.; Loewen, H.; Goedheer, W. J.; Fortov, V. E.; Lipaev, A. M.; Molotkov, V. I.; Petrov, O. F.

    2009-02-27

    The dynamical onset of lane formation is studied in experiments with binary complex plasmas under microgravity conditions. Small microparticles are driven and penetrate into a cloud of big particles, revealing a strong tendency towards lane formation. The observed time-resolved lane-formation process is in good agreement with computer simulations of a binary Yukawa model with Langevin dynamics. The laning is quantified in terms of the anisotropic scaling index, leading to a universal order parameter for driven systems.

  17. Microscale imaging of cilia-driven fluid flow

    PubMed Central

    Huang, Brendan K.; Choma, Michael A.

    2015-01-01

    Cilia-driven fluid flow is important for multiple processes in the body, including respiratory mucus clearance, gamete transport in the oviduct, right-left patterning in the embryonic node, and cerebrospinal fluid circulation. Multiple imaging techniques have been applied towards quantifying ciliary flow. Here we review common velocimetry methods of quantifying fluid flow. We then discuss four important optical modalities, including light microscopy, epifluorescence, confocal microscopy, and optical coherence tomography, that have been used to investigate cilia-driven flow. PMID:25417211

  18. Mass Transfers for Pressure and Boundary Driven Periodic Flow

    NASA Astrophysics Data System (ADS)

    Thomas, Aaron M.; Narayanan, R.

    1997-11-01

    Enhancing the mass transfer of species from one reservoir to another can be achieved by imposing a periodic flow to the system. Periodic flow is obtained using two different mechanisms: an oscillating pressure drop or oscillating the boundary of the system to produce either a periodic Poiseuille or Couette flow, respectively. A simple calculation of an oscillating flat plate in a semi-infinite fluid reveals the process to be dependent on the viscous and mass transfer boundary layers. For gases, the mass transfer of the lighter species is greater than the heavier species, whereas for liquids, the mass transfer of the lighter species is less than the heavier species. In modeling a finite system of parallel plates with either an imposed periodic pressure drop from a piston or oscillating the plates at the same frequency, it is calculated that the mass transfer of the pressure driven system is higher than that for the boundary driven system for all scaled frequencies. However, more power is required to drive the pressure driven system than the boundary driven system, and we find that the mass transfer per power of the pressure driven and boundary driven system are equal to one another.

  19. Science-Driven Computing: NERSC's Plan for 2006-2010

    SciTech Connect

    Simon, Horst D.; Kramer, William T.C.; Bailey, David H.; Banda,Michael J.; Bethel, E. Wes; Craw, James M.; Fortney, William J.; Hules,John A.; Meyer, Nancy L.; Meza, Juan C.; Ng, Esmond G.; Rippe, Lynn E.; Saphir, William C.; Verdier, Francesca; Walter, Howard A.; Yelick,Katherine A.

    2005-05-16

    NERSC has developed a five-year strategic plan focusing on three components: Science-Driven Systems, Science-Driven Services, and Science-Driven Analytics. (1) Science-Driven Systems: Balanced introduction of the best new technologies for complete computational systems--computing, storage, networking, visualization and analysis--coupled with the activities necessary to engage vendors in addressing the DOE computational science requirements in their future roadmaps. (2) Science-Driven Services: The entire range of support activities, from high-quality operations and user services to direct scientific support, that enable a broad range of scientists to effectively use NERSC systems in their research. NERSC will concentrate on resources needed to realize the promise of the new highly scalable architectures for scientific discovery in multidisciplinary computational science projects. (3) Science-Driven Analytics: The architectural and systems enhancements and services required to integrate NERSC's powerful computational and storage resources to provide scientists with new tools to effectively manipulate, visualize, and analyze the huge data sets derived from simulations and experiments.

  20. Studies of Radiation-Driven and Buoyancy-Driven Fluid Flows and Transport

    NASA Technical Reports Server (NTRS)

    Ronney, Paul D.; Fortmeyer, Justin M.

    1994-01-01

    It is well known that radiative heat transport influences many types of buoyant flows due to its effect on the temperature and thus density field in the fluid medium. It is of interest to study gaseous flows driven solely by radiation in the absence of buoyancy, particularly because of its application to astrophysical flows that are well known from astronomical observations and numerical simulation. However, no laboratory-scale experiments of this phenomenon have ever been conducted. To study the possibility of obtaining such flows in the laboratory, an apparatus was built to produce large temperature differences (Delta T) up to 300 K in a gas confined between flat parallel plates. SF6 was used as the radiatively-active gas because its Planck absorption length is much shorter than that of any other common non-reactive gas. The NASA-Lewis 2.2 second drop tower was used to obtain reduced gravity in order to suppress buoyancy effects. To image the resulting flows, a laser shearing interferometer was employed. Initial results indicate the presence of flow that does not appear to be attributable to the residual flow resulting from buoyancy influences before the drop. For Delta T greater than 70 K, slight deformations in the interferometer fringes seen at lower Delta T became large unsteady swirls. Such behavior did not occur for radiatively-inactive gases, suggesting that a flow driven solely by radiation was obtained in SF6 and to a lesser extent in CO2 This was more pronounced at higher pressures and plate spacings, consistent with our scaling predictions.