Science.gov

Sample records for multi-mode fiber coarse

  1. Multi-mode fiber coarse WDM grating router using broadband add/drop filters for wavelength re-use

    SciTech Connect

    Bond, S W; Deri, R J; Larson, M C; Lowry, M E; Patel, R R; Pocha, M D

    1999-06-01

    For single mode fiber (SMF) applications the arrayed waveguide grating router (AWG) provides passive wavelength routing with spectral channels being used more than once in the routing table to achieve full NxN interconnection with only N wavelengths[l]. AWGs cannot be used with MMF due to the excessive losses in coupling from MMF to single mode waveguides. We report the development of a wavelength router (NxN wavelength multiplexer) for use in h and lF based optical networks. The device uses a blazed diffraction grating and broadband add/drop filters to provide wavelength re-use thus enabling fully non-blocking NxN interconnection with only N wavelengths. Initial experimental results using 3 inputs and 3 outputs are presented.

  2. Object recognition through a multi-mode fiber

    NASA Astrophysics Data System (ADS)

    Takagi, Ryosuke; Horisaki, Ryoichi; Tanida, Jun

    2017-04-01

    We present a method of recognizing an object through a multi-mode fiber. A number of speckle patterns transmitted through a multi-mode fiber are provided to a classifier based on machine learning. We experimentally demonstrated binary classification of face and non-face targets based on the method. The measurement process of the experimental setup was random and nonlinear because a multi-mode fiber is a typical strongly scattering medium and any reference light was not used in our setup. Comparisons between three supervised learning methods, support vector machine, adaptive boosting, and neural network, are also provided. All of those learning methods achieved high accuracy rates at about 90% for the classification. The approach presented here can realize a compact and smart optical sensor. It is practically useful for medical applications, such as endoscopy. Also our study indicated a promising utilization of artificial intelligence, which has rapidly progressed, for reducing optical and computational costs in optical sensing systems.

  3. Object recognition through a multi-mode fiber

    NASA Astrophysics Data System (ADS)

    Takagi, Ryosuke; Horisaki, Ryoichi; Tanida, Jun

    2017-02-01

    We present a method of recognizing an object through a multi-mode fiber. A number of speckle patterns transmitted through a multi-mode fiber are provided to a classifier based on machine learning. We experimentally demonstrated binary classification of face and non-face targets based on the method. The measurement process of the experimental setup was random and nonlinear because a multi-mode fiber is a typical strongly scattering medium and any reference light was not used in our setup. Comparisons between three supervised learning methods, support vector machine, adaptive boosting, and neural network, are also provided. All of those learning methods achieved high accuracy rates at about 90% for the classification. The approach presented here can realize a compact and smart optical sensor. It is practically useful for medical applications, such as endoscopy. Also our study indicated a promising utilization of artificial intelligence, which has rapidly progressed, for reducing optical and computational costs in optical sensing systems.

  4. A biconical taper multi-mode fiber SERS sensor

    NASA Astrophysics Data System (ADS)

    Bai, Hua; Chen, Zhenyi; Chen, Na; Guo, Qiang; Zhang, Kun; Pang, Fufei; Wang, Tingyun

    2010-12-01

    A surface-enhanced Raman scattering (SERS) optical fiber sensor using biconical taper multi-mode fiber (MMF) is proposed. It is fabricated by fused elongating a multi-mode fiber and then coated the silver colloid on its waist. The main advantage of this sensor is that it can increase the SERS active substrate region to make more molecules be excited to produce Raman signal. Silver colloid is selected as the active substrate of SERS. A modified immobilizing process is introduced to increase the thickness of the immobilized layer and reduce the preparation time. Various concentration of R6G is used to detect the performance of the sensor. Strong Raman signal is detected from the waist of the tapered fiber. The detection sensitivity is up to 10-9M.

  5. Resolution limits for imaging through multi-mode fiber.

    PubMed

    Mahalati, Reza Nasiri; Gu, Ruo Yu; Kahn, Joseph M

    2013-01-28

    We experimentally demonstrate endoscopic imaging through a multi-mode fiber (MMF) in which the number of resolvable image features approaches four times the number of spatial modes per polarization propagating in the fiber. In our method, a sequence of random field patterns is input to the fiber, generating a sequence of random intensity patterns at the output, which are used to sample an object. Reflected power values are returned through the fiber and linear optimization is used to reconstruct an image. The factor-of-four resolution enhancement is due to mixing of modes by the squaring inherent in field-to-intensity conversion. The incoherent point-spread function (PSF) at the center of the fiber output plane is an Airy disk equivalent to the coherent PSF of a conventional diffraction-limited imaging system having a numerical aperture twice that of the fiber. All previous methods for imaging through MMF can only resolve a number of features equal to the number of modes. Most of these methods use localized intensity patterns for sampling the object and use local image reconstruction.

  6. An SMS (single mode - multi mode - single mode) fiber structure for vibration sensing

    NASA Astrophysics Data System (ADS)

    Waluyo, T. B.; Bayuwati, D.

    2017-04-01

    We describe an SMS (single mode - multi mode - single mode) fiber structure to be used in a vibration sensing system. The fiber structure was fabricated by splicing a section (about 300 mm in length) of a step index multi mode fiber between two single mode fibers obtained from a communication grade fiber patchcord. Interference between higher order modes occurs while light from a narrow band light source travels along the multi mode fiber. When the multi mode fiber vibrates, the refractive index profile is changed because of the photo-elastics effect and the amplitude of the interference pattern is changed accordingly. To simulate a vibrating structure we used a loudspeaker to vibrate a wooden table. By using a digital oscilloscope, we recorded and analysed the vibrating signals obtained from the SMS fiber structure as well as from a GS-32CT geophone for referencing. We observed that this SMS fiber structure was potential to be used in a vibration sensing system with a measurement range from 30 to 180 Hz with inherent optical fiber sensor advantages such as light weight, immune to electromagnetic interference, and no electricity in the sensing part.

  7. Selection of energy optimized pump concepts for multi core and multi mode erbium doped fiber amplifiers.

    PubMed

    Krummrich, Peter M; Akhtari, Simon

    2014-12-01

    The selection of an appropriate pump concept has a major impact on amplifier cost and power consumption. The energy efficiency of different pump concepts is compared for multi core and multi mode active fibers. In preamplifier stages, pump power density requirements derived from full C-band low noise WDM operation result in superior energy efficiency of direct pumping of individual cores in a multi core fiber with single mode pump lasers compared to cladding pumping with uncooled multi mode lasers. Even better energy efficiency is achieved by direct pumping of the core in multi mode active fibers. Complexity of pump signal combiners for direct pumping of multi core fibers can be reduced by deploying integrated components.

  8. Research on optical fiber magnetic field sensors based on multi-mode fiber and spherical structure

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Tong, Zheng-rong; Zhang, Wei-hua; Luan, Pan-pan; Zhao, Yue; Xue, Li-fang

    2017-01-01

    A magnetic field sensor with a magnetic fluid (MF)-coated intermodal interferometer is proposed and experimentally demonstrated. The interferometer is formed by sandwiching a segment of single mode fiber (SMF) between a segment of multi-mode fiber (MMF) and a spherical structure. It can be considered as a cascade of the traditional SMF-MMF-SMF structure and MMF-SMF-sphere structure. The transmission spectral characteristics change with the variation of applied magnetic field. The experimental results exhibit that the magnetic field sensitivities for wavelength and transmission loss are 0.047 nm/mT and 0.215 dB/mT for the interference dip around 1 535.36 nm. For the interference dip around 1548.41nm, the sensitivities are 0.077 nm/mT and 0.243 dB/mT. Simultaneous measurement can be realized according to the different spectral responses.

  9. The application of tapered multi-mode fiber in laser signal simulation

    NASA Astrophysics Data System (ADS)

    Yin, Ruiguang; Guo, Hao; Liang, Weiwei; Zhang, Wenpan; Li, Hui

    2016-09-01

    According to laser signal simulation, the advantage of application of tapered multi-mode fiber on laser pulse signal transmission was analyzed. By optical system simulation, the effect on the coupling efficiency of 1.06μm laser pulse signal of different angle was analyzed. By optical experiment, the coupling efficiency and transmission mode of different incident angle and force condition were confirmed. Combining the application of simulation system, with convex lens, frosted glass and optical integrator on the outlet of fiber, the far-field energy distribution was measured. According the receiving optical system entrance pupil, the effect on the beam quality to the simulation result was analyzed. The results showed that the application of tapered multi-mode fiber on laser pulse signal simulation is feasible, and the equipment has been used in the engineering projects.

  10. Color digital holography using speckle illumination by means of a multi-mode fiber

    NASA Astrophysics Data System (ADS)

    Funamizu, Hideki; Shimoma, Shohei; Aizu, Yoshihisa

    2014-02-01

    We present color digital holography using speckle illumination by means of a multi-mode fiber. In this technique, speckle fields emitted from the fiber are used as both a reference wave and a wavefront illuminating an object. For three wavelengths, the interference patterns of two coherent waves are recorded as digital holograms on a CCD camera. A speckle method is used for suppressing DC terms and reducing a twin image in an in-line color digital holography. The speckle fields are changed by vibrating the multi-mode fiber using a vibrator, and a number of holograms are acquired to average reconstructed images. The dependence of the averaged number of holograms on color quality of reconstructed images is evaluated by chromaticity coordinates and color differences in colorimetry.

  11. Demonstration of polarization modulated signals in a multi-mode GdFe-silica hybrid fiber

    NASA Astrophysics Data System (ADS)

    Nishibayashi, K.; Yoneda, H.; Kuga, K.; Matsuda, T.; Munekata, H.

    2015-04-01

    We fabricate a hybrid fiber composed of a multi-mode, silica-based fiber and a GdFe thin film adjacent to each other. Magneto-optical (MO) signals modulated by AC magnetic fields on the GdFe layer are detected at the output pupil of the fiber, showing that the polarization state of the propagated light in the mixed-mode condition can be well defined. We find that local modulation of magnetization at different positions of the GdFe layer results in MO signals at the different position of the output, showing the spatial de-multiplexing of polarization modulated signals.

  12. Orientation-recognized rotation measurement using single polarimetric multi-mode tilted fiber grating

    NASA Astrophysics Data System (ADS)

    Liu, Fu; Guo, Tuan; Shang, Libin; Zhang, Zhaochuan; Du, Fa; Guan, Bai-Ou; Albert, Jacques

    2014-05-01

    The polarimetric sensing characteristics of multi-mode-fiber based tilted fiber Bragg grating (MMF-TFBG) have been analyzed and experimentally demonstrated. The physical "enlarged" fiber core enables the tilted gratings to excite multi high-order core modes with significantly different polarization dependence and well-defined "comb" profiles which are spectrally separated at different wavelength. Orientation-recognized twist/rotation measurement (-90o to 90o) has been achieved with sensitivity of 0.075 dB/deg by using a cost-effective double-path power detection (power monitoring of two orthogonal-polarimetric odd core-modes, i.e. LP11 and LP12).

  13. Note: Coupling of multiple laser diodes into a multi-mode fiber.

    PubMed

    Ivonyak, Y; Piechal, B; Mrozowicz, M; Bercha, A; Trzeciakowski, W

    2014-03-01

    Diode lasers are coupled to a multi-mode fiber (with 100-400 μm core) using a reflector in the form of a regular pyramid. The optimization of the optical setup allows to couple 60%-90% of light into the fiber. The demonstrator achieves 3.5 W in the 100/125 μm fiber with 8 violet (405 nm) diodes, 5.5 W in the 100/125 μm fiber with 8 blue (445 nm) diodes, and 3.3 W in the 200/250 μm fiber with red (638 nm) diodes. The device can work with lasers emitting at many different wavelengths, including green (532 nm) frequency-doubled lasers. Our work was motivated by potential medical applications of these laser sources.

  14. LLNL Measurements of Graded-Index Multi-Mode Fiber (ITF 47)

    SciTech Connect

    Saito, T.T.

    2000-05-01

    The Russian Federal Nuclear Center-All Russian Research Institute of Technical Physics, located in the Nuclear City of Snezhinsk, east of the Ural mountains and the Lawrence Livermore National Laboratories have been investigating the possibility of establishing a commercial optical fiber manufacturing facility. These discussions began in the summer of 1998. At that time three samples (single mode and multi-mode) of optical fiber were left at the Sandia National Laboratory. Sandia measured two of the segments and sent them to LLNL. The optical loss at 1550 nm and 1300 nm were higher than commercially available fiber. The measurements were complicated because the geometry of the fibers also did not meet specification. Since the core was not adequately centered coupling of optical energy into the fiber being tested varied widely depending on which end of the fiber was used for insertion. The results of these measurements were summarized in the informal report dated June 11, 1999, which was hand carried by Dr. Paul Herman during his July 1999 visit. During the July visit a 1.2-km long section of graded-index multimode fiber, ITF 47, was given to Herman. We had requested samples longer than the earlier ones (which were {approx}0.1 km long) in order that a cutback method could be used for the transmission measurements. The optical loss using the cutback technique and the transmission spectral measurements in the 600-1700 mn region are reported. Also physical measurements are reported of the fiber's diameter, concentricity, ellipticity and tensile strength (proof test). The test results are summarized in Table 1, ''Comparative Data for Multi-mode Optical Fiber.'' The table includes the values from the Industrial specification TIA/EIA 402AAAB, the commercial specification for Corning's 50/125 CPC6, the values measured on ITF-47 and provided by C-70, and LLNL's values for ITF-47 as well as the multimode values from the June 1999 samples.

  15. Energy enhancements in mode-locked laser cavities using multi-mode fiber lasers

    NASA Astrophysics Data System (ADS)

    Ding, Edwin; Kutz, J. Nathan

    2010-02-01

    The averaged mode-locking dynamics in a multi-mode fiber is studied. The transverse mode structures of the electric field are determined from a linear eigenvalue problem, and the co-propagation of the corresponding mode envelopes is governed by a system of coupled Ginzburg-Landau equations (CGLEs) which accounts explicitly for bandwidth-limited saturable gain as well as saturable absorption. Simulations show that stable and robust modelocked pulses with high energy can be produced. The maximum pulse energy is simulated as a function of the linear coupling and coiling loss. The present work provides for an excellent tool for characterizing mode-locking performance.

  16. An integrated photoluminescence sensing platform using a single-multi-mode fiber coupler-based probe.

    PubMed

    Long, Feng; Zhu, Anna; Shi, Hanchang

    2014-03-21

    We demonstrate an integrated fiber optic photoluminescence sensing platform using a novel single-multi-mode fiber coupler (SMFC)-based probe with high collection efficiency for fluorescence signals. The SMFC, prepared using fused biconical taper technology, not only transmits excitation light, but also collects and transmits fluorescence. The entire system does not use complex optical components and rarely requires optical alignment. The simple structure of the SMFC considerably improves the light transmission efficiency, signal-to-noise ratio, and sensitivity of the system. Theoretical and experimental results show that the proposed probe increases the collection efficiency by more than eight-fold compared with a bifurcated fiber probe. The performance of the proposed probe was experimentally evaluated by measuring the fluorescence spectra of well-known targets and a fresh Tall Fescue leaf.

  17. Splice loss requirements in multi-mode fiber mode-division-multiplex transmission links.

    PubMed

    Warm, Stefan; Petermann, Klaus

    2013-01-14

    We investigate numerically the influence of fiber splices and fiber connectors to the statistics of mode dependent loss (MDL) and multiple-input multiple-output (MIMO) outage capacity in mode multiplexed multi-mode fiber links. Our results indicate required splice losses much lower than currently feasible to achieve a reasonable outage capacity in long-haul transmission systems. Splice losses as low as 0.03dB may effectively lead to an outage of MIMO channels after only a few hundred kilometers transmission length. In a first approximation, the relative capacity solely depends on the accumulated splice loss and should be less than ≈ 2dB to ensure a relative capacity of 90%. We also show that discrete mode permutation (mixing) within the transmission line may effectively increase the maximum transmission distance by a factor of 5 for conventional splice losses.

  18. Refractive index sensors based on the fused tapered special multi-mode fiber

    NASA Astrophysics Data System (ADS)

    Fu, Xing-hu; Xiu, Yan-li; Liu, Qin; Xie, Hai-yang; Yang, Chuan-qing; Zhang, Shun-yang; Fu, Guang-wei; Bi, Wei-hong

    2016-01-01

    In this paper, a novel refractive index (RI) sensor is proposed based on the fused tapered special multi-mode fiber (SMMF). Firstly, a section of SMMF is spliced between two single-mode fibers (SMFs). Then, the SMMF is processed by a fused tapering machine, and a tapered fiber structure is fabricated. Finally, a fused tapered SMMF sensor is obtained for measuring external RI. The RI sensing mechanism of tapered SMMF sensor is analyzed in detail. For different fused tapering lengths, the experimental results show that the RI sensitivity can be up to 444.517 81 nm/RIU in the RI range of 1.334 9—1.347 0. The RI sensitivity is increased with the increase of fused tapering length. Moreover, it has many advantages, including high sensitivity, compact structure, fast response and wide application range. So it can be used to measure the solution concentration in the fields of biochemistry, health care and food processing.

  19. LLNL Measurements of Graded-Index Multi-Mode Optical Fiber (ITF 47)

    NASA Astrophysics Data System (ADS)

    Saito, T. T.

    2000-05-01

    The Russian Federal Nuclear Center-All Russian Research Institute of Technical Physics, located in the Nuclear City of Snezhinsk, east of the Ural mountains and the Lawrence Livermore National Laboratories have been investigating the possibility of establishing a commercial optical fiber manufacturing facility. These discussions began in the summer of 1998. At that time three samples (single mode and multi-mode) of optical fiber were left at the Sandia National Laboratory. Sandia measured two of the segments and sent them to LLNL. The optical loss at 1550 nm and 1300 nm were higher than commercially available fiber. The measurements were complicated because the geometry of the fibers also did not meet specification. Since the core was not adequately centered coupling of optical energy into the fiber being tested varied widely depending on which end of the fiber was used for insertion. The results of these measurements were summarized in the informal report dated June 11, 1999, which was hand carried by Dr. Paul Herman during his July 1999 visit. During the July visit a 1.2-km long section of graded-index multimode fiber, ITF 47, was given to Herman. We had requested samples longer than the earlier ones (which were (approx) 0.1 km long) in order that a cutback method could be used for the transmission measurements. The optical loss using the cutback technique and the transmission spectral measurements in the 600-1700 mn region are reported. Also physical measurements are reported of the fiber's diameter, concentricity, ellipticity and tensile strength (proof test).

  20. Laser Welding of Copper Using Multi Mode Fiber Lasers at Near Infrared Wavelength

    NASA Astrophysics Data System (ADS)

    Liebl, S.; Wiedenmann, R.; Ganser, A.; Schmitz, P.; Zaeh, M. F.

    Due to the increasing electrification of automotive drives and the expansion of decentralized renewable energygeneration, the consumption of copper for the fabrication of electrical components such as electric motors or conducting paths increases. To jointhese components, laser welding is more frequently used since it represents a flexible and fully automatable joining process. Because of the high thermal conductivity, the low absorption coefficient forinfrared wavelength of common laser beam sources and the resulting limited process efficiency, welding of copper alloys represents a major challenge for laser assisted processes. In this paper, experimental investigationsare presented to identify arising process limits during laser welding of pure copper materials with multi-mode fiber lasers at near infrared wavelength depending on the applied laser power and welding velocity. In addition, a potential stabilization of the welding process by shielding gas support was examined. Further investigations were focused on the influence of shielding gas on the molten pool geometry.

  1. Label free imaging system for measuring blood flow speeds using a single multi-mode optical fiber (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Sigal, Iliya; Caravaca Aguirre, Antonio M.; Gad, Raanan; Piestun, Rafael; Levi, Ofer

    2016-03-01

    We demonstrate a single multi-mode fiber-based micro-endoscope for measuring blood flow speeds. We use the transmission-matrix wavefront shaping approach to calibrate the multi-mode fiber and raster-scan a focal spot across the distal fiber facet, imaging the cross-polarized back-reflected light at the proximal facet using a camera. This setup allows assessment of the backscattered photon statistics: by computing the mean speckle contrast values across the proximal fiber facet we show that spatially-resolved flow speed maps can be inferred by selecting an appropriate camera integration time. The proposed system is promising for minimally-invasive studies of neurovascular coupling in deep brain structures.

  2. Refractive index sensor based on multi-mode plastic optical fiber with long period grating

    NASA Astrophysics Data System (ADS)

    Teng, Chuanxin; Yu, Fangda; Ding, Yue; Zheng, Jie

    2017-05-01

    A multi-mode plastic optical fiber (POF) with a long period grating (LPG) was proposed for a refractive index (RI) sensing probe. The LPG was fabricated on the surface of the POF by a simple die-press-print method using a commercial available thread rod as the mould. The RI sensing performances for straight and U-shaped POFs with LPGs were studied. It is found that the straight RI sensing probe with LPG structure was not sensitive enough for RI measurement. After bending the straight POF probes with LPGs into U-shaped probes, the RI sensing performance was improved markedly. By altering the structural parameters, the RI sensing performances of the U-shaped POF probes with LPGs were optimized, a sensitivity of 1130%/RIU with a resolution of 8.44×10-4 in the RI range of 1.33-1.41 was obtained. The probe is a low cost solution for RI sensing purpose, which has the features of simple structure, easy fabrication, compact size and intensity modulation at visible wavelengths.

  3. Ultra-thin rigid endoscope: two-photon imaging through a graded-index multi-mode fiber.

    PubMed

    Sivankutty, Siddharth; Andresen, Esben Ravn; Cossart, Rosa; Bouwmans, Géraud; Monneret, Serge; Rigneault, Hervé

    2016-01-25

    Rigid endoscopes like graded-index (GRIN) lenses are known tools in biological imaging, but it is conceptually difficult to miniaturize them. In this letter, we demonstrate an ultra-thin rigid endoscope with a diameter of only 125 μm. In addition, we identify a domain where two-photon endoscopic imaging with fs-pulse excitation is possible. We validate the ultra-thin rigid endoscope consisting of a few cm of graded-index multi-mode fiber by using it to acquire optically sectioned two-photon fluorescence endoscopic images of three-dimensional samples.

  4. Blade tip clearance measurement of the turbine engines based on a multi-mode fiber coupled laser ranging system

    SciTech Connect

    Guo, Haotian; Duan, Fajie; Wu, Guoxiu; Zhang, Jilong

    2014-11-15

    The blade tip clearance is a parameter of great importance to guarantee the efficiency and safety of the turbine engines. In this article, a laser ranging system designed for blade tip clearance measurement is presented. Multi-mode fiber is utilized for optical transmission to guarantee that enough optical power is received by the sensor probe. The model of the tiny sensor probe is presented. The error brought by the optical path difference of different modes of the fiber is estimated and the length of the fiber is limited to reduce this error. The measurement range in which the optical power received by the probe remains essentially unchanged is analyzed. Calibration experiments and dynamic experiments are conducted. The results of the calibration experiments indicate that the resolution of the system is about 0.02 mm and the range of the system is about 9 mm.

  5. Deep optical access on multi-core and multi-mode fiber for integrated wireless applications

    NASA Astrophysics Data System (ADS)

    Llorente, Roberto; Morant, Maria; Beltrán, Marta; Macho, Andrés.

    2015-01-01

    Deep integrated optical access networks target to provide great capillarity and multiple ONTs for cost- and energy-efficient pervasive connectivity seamless supporting integrated wireless. Several key optical technologies are herein reported supporting integrated deep optical access: Bundled radio-over-fiber transmission is proposed and demonstrated for the provision of quintuple-play services achieving 125 km SSMF optical reach. Bend-insensitive fiber in-building distribution is also proposed and demonstrated supporting joint legacy coaxial transmission. Multimode POF is also proposed and demonstrated suitable for joint in-building distribution of MATV and SMATV broadcasting signals. Optical comb technology us is also demonstrated suitable for mm-wave radio generation of multiband OFDM wireless signals. Finally, multicore fiber transmission is also proposed and demonstrated suitable for the transmission of LTE and WIMAX in wireless fronthaul applications in a minimized inter-core crosstalk penalty configuration.

  6. Calibration for single multi-mode fiber digital scanning microscopy imaging system

    NASA Astrophysics Data System (ADS)

    Yin, Zhe; Liu, Guodong; Liu, Bingguo; Gan, Yu; Zhuang, Zhitao; Chen, Fengdong

    2015-11-01

    Single multimode fiber (MMF) digital scanning imaging system is a development tendency of modern endoscope. We concentrate on the calibration method of the imaging system. Calibration method comprises two processes, forming scanning focused spots and calibrating the couple factors varied with positions. Adaptive parallel coordinate algorithm (APC) is adopted to form the focused spots at the multimode fiber (MMF) output. Compare with other algorithm, APC contains many merits, i.e. rapid speed, small amount calculations and no iterations. The ratio of the optics power captured by MMF to the intensity of the focused spots is called couple factor. We setup the calibration experimental system to form the scanning focused spots and calculate the couple factors for different object positions. The experimental result the couple factor is higher in the center than the edge.

  7. [Spectra modulated surface plasmon resonance sensor based on side polished multi-mode optical fiber].

    PubMed

    Luo, Yun-Han; Chen, Xiao-Long; Xu, Meng-Yun; Ge, Jia; Zhang, Yi-Long; He, Yong-Hong; Tang, Jie-Yuan; Yu, Jian-Hui; Zhang, Jun; Chen, Zhe; Chen, Xing-Dan

    2014-03-01

    Surface plasmon resonance, which utilizes the resonance of optical evanescent wave with the metal surface plasmon wave, has been developed into a high sensitivity, rapid, label-less measurement method for chemical and biological analysis. In order to improve the spectral sensitivity in refractive index for a side polished fiber surface plasmon resonance sensor, the whole cladding layer and part of core of a multimode fiber was polished off. Additionally, an extra chrome layer with relatively high refractive index was coated on the polished zone before a gold film. The results showed that the sensor can measure the refractive index range from 1.333 to 1. 431 RIU, with the average spectral sensitivity of 4.11 x 10(3) nm RIU(-1), which is better than the reported results. Especially, in the refractive index range of 1. 417 1. 431 RIU, the sensitivity reaches to 1.09 x 10(4) nm RIU(-1). The minimum resolution of approximately 3.6 x 10(-5) RIU was estimated by a combination analysis with the sensor sensitivity and stability. The superiorities possessed by the proposed sensor in high sensitivity, wide detection range, small size and good stability and reproducibility, etc., make it a good candidate for food testing, environmental monitoring, biomedical testing and other related fields.

  8. A 25-Gb/s 100-m multi-mode fiber optical link based on 1.3μm lens-integrated surface-emitting laser and CMOS receiver

    NASA Astrophysics Data System (ADS)

    Takemoto, Takashi; Yamashita, Hiroki; Matsuoka, Yasunobu; Adachi, Koichiro; Lee, Yong

    2014-02-01

    A 1.3-μm wavelength optical link, which consists of a lens-integrated laser diode and a CMOS optical receiver, was developed. It achieves 25-Gb/s error-free 100-m multi-mode fiber transmission with sensitivity of -6.3-dBm OMA.

  9. Design of SMS (Single mode-Multi mode coreless-Single mode) optical fiber as corrosion sensor

    NASA Astrophysics Data System (ADS)

    Aisyah, Putri Yeni; Hatta, Agus M.; Pratama, Detak Yan

    2016-11-01

    Conventional corrosion sensors such as ultrasonic guided waves, eddy current and thermography have been widely applied, however, these sensors have disadvantage of suffering from additional damage, as these sensors are placed in corrosive environment, often hidden and could not be directly observed, therefore corrosion inspection using conventional sensor is much more expensive and time consuming. Usage of optical fiber as corrosion sensor, based on changes in light intensity due to corrosion effect, is an alternative to overcome the disadvantage of conventional sensors. We proposed to use Single mode - Multimode Coreless - Single mode structured optical fiber as sensor. Multimode section of the optical fiber is coated with aluminium as the corrosion object. Experiment result shows that the corrosion process have an effect of decreasing the output sensor power as the corrosion rate increasing. Experimental test is conducted on the sensor, in which time interval of corrosion treatment is 9 hours. It is obtained from the test result that the highest value of output power is 13.19 dBm. Furthermore when the weight loss range of aluminium layer is 0 - 140 mg after corrosion treatment and the length of multimode fiber is 10 mm, the highest sensitivity of the sensor is 0.094 dBm/mg.

  10. High-speed reconfigurable card-to-card optical interconnects based on hybrid free-space and multi-mode fiber propagations.

    PubMed

    Wang, Ke; Nirmalathas, Ampalavanapillai; Lim, Christina; Skafidas, Efstratios; Alameh, Kamal

    2013-12-16

    In this paper, a high-speed reconfigurable card-to-card optical interconnect architecture based on hybrid free-space and multi-mode fiber (MMF) propagation is proposed. The use of free-space signal transmission provides flexibility and reconfigurability and the MMF extends the achievable interconnection range. A printed-circuit-board (PCB) based integrated optical interconnect module is designed and developed and proof-of-concept demonstration experiments are carried out. Results show that 3 × 10 Gb/s reconfigurable optical interconnect is realized with ~12 cm free-space propagation and a 10 m MMF length. In addition, since air turbulence due to high temperature of electronic components and heat dissipation fans always exists in typical interconnect environments and it normally results in system performance degradation, its impact on the proposed reconfigurable optical interconnect scheme is also experimentally investigated. Results indicate that even with comparatively strong air turbulence, 3 × 10 Gb/s optical interconnects with flexibility can still be achieved and the power penalty is <0.7 dB.

  11. Development of a cable reel development system using a rotary joint for kilometer lengths of two-fiber multi-mode fiber optic cable

    SciTech Connect

    Curtiss, J.A.; Jahelka, J.R.

    1995-08-11

    Brookhaven National Laboratory (BNL) recently developed a two-component system for use during remote inspections. The system consists of a mobile unit with television cameras and other equipment and a stationary base station. A variety of signals must be continually transmitted between the two system components as the mobile unit is moved from the location to another. Two channels of broadband (10MHz) NTSC video are transmitted from the mobile unit to the base station, and a bi-directional ``talk set`` provides audio communication between personnel at each location. In addition, several channels of RS-232 are required to support present and future instruments used at the mobile unit and controlled by personnel at the base station. Brookhaven developed a mobile unit which communicated with a base station over a 2-fiber multimode fiber optic cable. One of the design requirements was maintaining constant communication with the base station during the time the mobile unit was moved about. To provide uninterrupted communications, deployment of the 1-km long fiber optic cable was initially performed with a ``spinning reel`` mechanism. The spinning reel mechanism proved to be mechanically unsuitable, and so the cable deployment mechanism was redesigned to spool the cable off the reel. The requirement for uninterrupted communications required a two-channel fiber optic rotary joint in the design. Incorporation of the rotary joint into the design is described, and appropriate reference material is included.

  12. Optimal Parameter Design of Coarse Alignment for Fiber Optic Gyro Inertial Navigation System.

    PubMed

    Lu, Baofeng; Wang, Qiuying; Yu, Chunmei; Gao, Wei

    2015-06-25

    Two different coarse alignment algorithms for Fiber Optic Gyro (FOG) Inertial Navigation System (INS) based on inertial reference frame are discussed in this paper. Both of them are based on gravity vector integration, therefore, the performance of these algorithms is determined by integration time. In previous works, integration time is selected by experience. In order to give a criterion for the selection process, and make the selection of the integration time more accurate, optimal parameter design of these algorithms for FOG INS is performed in this paper. The design process is accomplished based on the analysis of the error characteristics of these two coarse alignment algorithms. Moreover, this analysis and optimal parameter design allow us to make an adequate selection of the most accurate algorithm for FOG INS according to the actual operational conditions. The analysis and simulation results show that the parameter provided by this work is the optimal value, and indicate that in different operational conditions, the coarse alignment algorithms adopted for FOG INS are different in order to achieve better performance. Lastly, the experiment results validate the effectiveness of the proposed algorithm.

  13. Multi-Mode Broadband Patch Antenna

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R. (Inventor)

    2001-01-01

    A multi-mode broad band patch antenna is provided that allows for the same aperture to be used at independent frequencies such as reception at 19 GHz and transmission at 29 GHz. Furthermore, the multi-mode broadband patch antenna provides a ferroelectric film that allows for tuning capability of the multi-mode broadband patch antenna over a relatively large tuning range. The alternative use of a semiconductor substrate permits reduced control voltages since the semiconductor functions as a counter electrode.

  14. Toward multiscale modeling of the chromatin fiber: a coarse grain model for DNA

    NASA Astrophysics Data System (ADS)

    Savelyev, Alexey; Papoian, Garegin

    2008-03-01

    In eukaryotic cells DNA is compacted a million-fold into a chromatin. Understanding the mechanism of chromatin folding is of great biological importance. All-atom Molecular Dynamics (MD) simulations could provide crucial insights into the electrostatic and structural mechanisms of chromatin folding. However, because of the enormous size of even short chromatin fiber segment and long folding time-scales, atomistic simulations are computationally impractical. Our long-term aim is to build an accurate coarse-grain (CG) model of the chromatin, derived systematically from all-atom simulations of its smaller parts. Here we report the development of the CG model for a linear DNA chain, playing the role of a linker DNA segment in the chromatin. We derived CG inter-DNA electrostatic potential from atomistic simulations with explicit solvent and mobile ions, instead of relying on the standard models of continuum electrostatics, which are inadequate at small intermolecular distances. In addition, we used the ideas of renormalization group theory to construct an optimization scheme for parameterizing the CG force field. This novel approach is designed to accurately reproduce correlations among various CG degrees of freedom. The implementation of these correlations was left as an open question in the prior studies of CG polymer models.

  15. Interactive multi-mode blade impact analysis

    NASA Technical Reports Server (NTRS)

    Alexander, A.; Cornell, R. W.

    1978-01-01

    The theoretical methodology used in developing an analysis for the response of turbine engine fan blades subjected to soft-body (bird) impacts is reported, and the computer program developed using this methodology as its basis is described. This computer program is an outgrowth of two programs that were previously developed for the purpose of studying problems of a similar nature (a 3-mode beam impact analysis and a multi-mode beam impact analysis). The present program utilizes an improved missile model that is interactively coupled with blade motion which is more consistent with actual observations. It takes into account local deformation at the impact area, blade camber effects, and the spreading of the impacted missile mass on the blade surface. In addition, it accommodates plate-type mode shapes. The analysis capability in this computer program represents a significant improvement in the development of the methodology for evaluating potential fan blade materials and designs with regard to foreign object impact resistance.

  16. Coarse WDM networking of self-referenced fiber-optic intensity sensors with reconfigurable characteristics.

    PubMed

    Montero, D S; Vázquez, C; Baptista, J M; Santos, J L; Montalvo, J

    2010-03-01

    A CWDM network operating in reflective configuration for multiplexing remote Radio-Frequency (RF) self-referenced fiber-optic intensity sensors is analyzed and experimentally investigated. In the described approach, the use of fiber Bragg gratings as spectral selective mirrors allows to implement delay lines in the electrical domain, achieving more compact sensor-heads and easy-reconfigurable sensing points. Two measurement parameters for the sensing heads are defined and comparatively studied in terms of design parameters, linearity, sensitivity and resolution. The proposed sensor configuration is modeled following the Z-transform formalism, which permits an easy analysis of the system frequency response. Experimental results are presented, showing the characterization of the network performance and considering the properties of sensor self-referencing as well as sensor crosstalk.

  17. Simultaneous measurement of dynamic displacement and strain in a single fiber using coarse wavelength-division multiplexing and fiber Bragg-grating filter-based sensing system.

    PubMed

    Chuang, Kuo-Chih; Ma, Chien-Ching; Wang, Hwa-Chun

    2016-03-20

    Displacement and strain, two of the most important physical quantities in experimental solid mechanics, are seldomly measured simultaneously in a single experimental configuration. In order to provide and improve corresponding sensing techniques, an experimental setup system for simultaneous measurement of dynamic displacement and strain on a flexible cantilever beam using two fiber Bragg gratings (FBGs) in a single fiber is proposed. To realize high-speed multiplexing and demodulation, a configuration incorporating a coarse wavelength-division multiplexing (CWDM) technique and an FBG transmission filter is implemented. The cantilever beam is subjected to steel-ball impact from which the dynamic multipoint displacement/strain sensing performances of the CWDM and FBG filter-based sensing system are demonstrated. Experimental results in temporal and frequency domain are compared with those obtained by the finite element method (FEM) predictions based on identification of the impact-loading history. A noncontact Fotonic displacement sensor and a polyvinylidene-fluoride film (PVDF) strain sensor are also used for comparison. With transient and resonant frequency simulations conducted by the FEM, loading effects of the sensing system are examined. The results obtained in this study indicate that the proposed CWDM and FBG filter-based sensing system is capable of performing simultaneous multipoint displacement/strain measurements in a single fiber with large bandwidth, high sensitivity, and low intensity loss.

  18. Coarse particle inclusion and lignocellulose-rich fiber addition in feed benefit performance and health of broiler chickens.

    PubMed

    Kheravii, Sarbast K; Swick, Robert A; Choct, Mingan; Wu, Shu-Biao

    2017-09-01

    Measures to improve gut health and nutrient digestibility have been sought due to in-feed antibiotics being phased out in poultry. The appropriate physical structure of feed ingredients and addition of dietary fiber may be beneficial in enhancing gut health in poultry. In this study, the effect of a lignocellulose-rich fiber source and corn particle size on broiler performance, gizzard development, nutrient digestibility, cecal microflora, and litter quality was evaluated. A total of 684 day-old male Ross 308 chicks were randomly allocated to 6 treatments with 6 replicate pens, each housing 19 birds. A 2 × 3 factorial arrangement of treatments was applied with the factors of: corn particle size (coarse: 2,982 μm or fine: 941 μm geometric mean diameter), and 3 levels of lignocellulose (0%, 1% or 2%). Significant particle size × fiber interaction was observed for feed conversion ratio (FCR) at d 10 (P < 0.05). The birds fed coarsely ground corn (CGC) had lower FCR than those fed finely ground corn (FGC) only at 2% of lignocellulose but not at 1% or no lignocellulose addition. Birds fed FGC were heavier (P < 0.001) at d 10. In contrast, at d 24 and 35, birds fed CGC had lower FCR than those fed FGC (P < 0.05). Ileal gross energy and protein digestibility increased in birds fed CGC compared with those fed FGC at d 24 (P < 0.05). Relative gizzard weight was higher (P < 0.05) on d 24 and 35 in birds fed CGC as compared to those fed FGC. Birds consumed 2% dietary lignocellulose had decreased counts of cecal Clostridium spp. compared to those with 1% lignocellulose (P < 0.05) at d 24. On d 35, both levels of lignocellulose had significantly decreased (P < 0.05) litter moisture content compared to the control. In conclusion, birds fed pelleted diets containing CGC exhibited improved FCR, and increased nutrient digestibility, which may have been caused by larger gizzards. Furthermore, dietary lignocellulose addition is beneficial to litter quality. © 2017 Poultry

  19. The attachment of α -synuclein to a fiber: A coarse-grain approach

    NASA Astrophysics Data System (ADS)

    Ilie, Ioana M.; den Otter, Wouter K.; Briels, Wim J.

    2017-03-01

    We present simulations of the amyloidogenic core of α-synuclein, the protein causing Parkinson's disease, as a short chain of coarse-grain patchy particles. Each particle represents a sequence of about a dozen amino acids. The fluctuating secondary structure of this intrinsically disordered protein is modelled by dynamic variations of the shape and interaction characteristics of the patchy particles, ranging from spherical with weak isotropic attractions for the disordered state to spherocylindrical with strong directional interactions for a β-sheet. Flexible linkers between the particles enable sampling of the tertiary structure. This novel model is applied here to study the growth of an amyloid fibril, by calculating the free energy profile of a protein attaching to the end of a fibril. The simulation results suggest that the attaching protein readily becomes trapped in a mis-folded state, thereby inhibiting further growth of the fibril until the protein has readjusted to conform to the fibril structure, in line with experimental findings and previous simulations on small fragments of other proteins.

  20. Norms of quantum Gaussian multi-mode channels

    NASA Astrophysics Data System (ADS)

    Frank, Rupert L.; Lieb, Elliott H.

    2017-06-01

    We compute the Sp→Sp norm of a general Gaussian gauge-covariant multi-mode channel for any 1 ≤ p < ∞ , where Sp is a Schatten space. As a consequence, we verify the Gaussian optimizer conjecture and the multiplicativity conjecture in these cases.

  1. Ultrasonic Motors Using Piezoelectric Ceramic Multi-Mode Vibrators

    NASA Astrophysics Data System (ADS)

    Takano, Takehiro; Tomikawa, Yoshiro; Ogasawara, Toshiharu; Sugawara, Sumio; Konnon, Masashi

    1988-01-01

    The purpose of this paper is to report development of an ultrasonic motor using piezoelectric ceramic multi-mode vibrators of circular or annular plates, in which degenerate horizontal vibration modes of the same or different form are used. Some constructions of the motor and its experimental characteristics are presented. The ultrasonic motor investigated herein shows special merit in its thin construction.

  2. Multi-mode reliability-based design of horizontal curves.

    PubMed

    Essa, Mohamed; Sayed, Tarek; Hussein, Mohamed

    2016-08-01

    Recently, reliability analysis has been advocated as an effective approach to account for uncertainty in the geometric design process and to evaluate the risk associated with a particular design. In this approach, a risk measure (e.g. probability of noncompliance) is calculated to represent the probability that a specific design would not meet standard requirements. The majority of previous applications of reliability analysis in geometric design focused on evaluating the probability of noncompliance for only one mode of noncompliance such as insufficient sight distance. However, in many design situations, more than one mode of noncompliance may be present (e.g. insufficient sight distance and vehicle skidding at horizontal curves). In these situations, utilizing a multi-mode reliability approach that considers more than one failure (noncompliance) mode is required. The main objective of this paper is to demonstrate the application of multi-mode (system) reliability analysis to the design of horizontal curves. The process is demonstrated by a case study of Sea-to-Sky Highway located between Vancouver and Whistler, in southern British Columbia, Canada. Two noncompliance modes were considered: insufficient sight distance and vehicle skidding. The results show the importance of accounting for several noncompliance modes in the reliability model. The system reliability concept could be used in future studies to calibrate the design of various design elements in order to achieve consistent safety levels based on all possible modes of noncompliance.

  3. Mode Launcher Design for the Multi-moded DLDS

    SciTech Connect

    Li, Zenghai

    2003-04-30

    The DLDS (Delay Line Distribution System) power delivery system proposed by KEK combines several klystrons to obtain the high peak power required to drive a TeV scale linear collider. In this system the combined klystron output is subdivided into shorter pulses by proper phasing of the sources, and each subpulse is delivered to various accelerator sections via separate waveguides. A cost-saving improvement suggested by SLAC is to use a single multimoded waveguide to deliver the power of all the subpulses. This scheme requires a mode launcher that can deliver each subpulse by way of a different waveguide mode through selective phasing of the sources when combining their power. We present a compact design for such a mode launcher that converts the power from four rectangular waveguide feeds to separate modes in a multi-moded circular guide through coupling slots. Such a design has been simulated and found to satisfy the requirements for high efficiency and low surface fields.

  4. Multi-mode ultrasonic welding control and optimization

    DOEpatents

    Tang, Jason C.H.; Cai, Wayne W

    2013-05-28

    A system and method for providing multi-mode control of an ultrasonic welding system. In one embodiment, the control modes include the energy of the weld, the time of the welding process and the compression displacement of the parts being welded during the welding process. The method includes providing thresholds for each of the modes, and terminating the welding process after the threshold for each mode has been reached, the threshold for more than one mode has been reached or the threshold for one of the modes has been reached. The welding control can be either open-loop or closed-loop, where the open-loop process provides the mode thresholds and once one or more of those thresholds is reached the welding process is terminated. The closed-loop control provides feedback of the weld energy and/or the compression displacement so that the weld power and/or weld pressure can be increased or decreased accordingly.

  5. Multi-mode clustering model for hierarchical wireless sensor networks

    NASA Astrophysics Data System (ADS)

    Hu, Xiangdong; Li, Yongfu; Xu, Huifen

    2017-03-01

    The topology management, i.e., clusters maintenance, of wireless sensor networks (WSNs) is still a challenge due to its numerous nodes, diverse application scenarios and limited resources as well as complex dynamics. To address this issue, a multi-mode clustering model (M2 CM) is proposed to maintain the clusters for hierarchical WSNs in this study. In particular, unlike the traditional time-trigger model based on the whole-network and periodic style, the M2 CM is proposed based on the local and event-trigger operations. In addition, an adaptive local maintenance algorithm is designed for the broken clusters in the WSNs using the spatial-temporal demand changes accordingly. Numerical experiments are performed using the NS2 network simulation platform. Results validate the effectiveness of the proposed model with respect to the network maintenance costs, node energy consumption and transmitted data as well as the network lifetime.

  6. Real-time multi-mode neutron multiplicity counter

    DOEpatents

    Rowland, Mark S; Alvarez, Raymond A

    2013-02-26

    Embodiments are directed to a digital data acquisition method that collects data regarding nuclear fission at high rates and performs real-time preprocessing of large volumes of data into directly useable forms for use in a system that performs non-destructive assaying of nuclear material and assemblies for mass and multiplication of special nuclear material (SNM). Pulses from a multi-detector array are fed in parallel to individual inputs that are tied to individual bits in a digital word. Data is collected by loading a word at the individual bit level in parallel, to reduce the latency associated with current shift-register systems. The word is read at regular intervals, all bits simultaneously, with no manipulation. The word is passed to a number of storage locations for subsequent processing, thereby removing the front-end problem of pulse pileup. The word is used simultaneously in several internal processing schemes that assemble the data in a number of more directly useable forms. The detector includes a multi-mode counter that executes a number of different count algorithms in parallel to determine different attributes of the count data.

  7. Physics basis of Multi-Mode anomalous transport module

    SciTech Connect

    Rafiq, T.; Kritz, A. H.; Luo, L.; Weiland, J.; Pankin, A. Y.

    2013-03-15

    The derivation of Multi-Mode anomalous transport module version 8.1 (MMM8.1) is presented. The MMM8.1 module is advanced, relative to MMM7.1, by the inclusion of peeling modes, dependence of turbulence correlation length on flow shear, electromagnetic effects in the toroidal momentum diffusivity, and the option to compute poloidal momentum diffusivity. The MMM8.1 model includes a model for ion temperature gradient, trapped electron, kinetic ballooning, peeling, collisionless and collision dominated magnetohydrodynamics modes as well as model for electron temperature gradient modes, and a model for drift resistive inertial ballooning modes. In the derivation of the MMM8.1 module, effects of collisions, fast ion and impurity dilution, non-circular flux surfaces, finite beta, and Shafranov shift are included. The MMM8.1 is used to compute thermal, particle, toroidal, and poloidal angular momentum transports. The fluid approach which underlies the derivation of MMM8.1 is expected to reliably predict, on an energy transport time scale, the evolution of temperature, density, and momentum profiles in plasma discharges for a wide range of plasma conditions.

  8. Nonlinear optics of multi-mode planar photonic crystal microcavities

    NASA Astrophysics Data System (ADS)

    McCutcheon, Murray William

    The nonlinear properties of multi-mode InP and Si planar photonic crystal microcavities are investigated in experiments relevant to integrated schemes for classical and quantum optical information processing. Normally incident, short laser pulses are used to coherently initialize the relative phase and amplitudes of two modes of a single-missing-hole InP microcavity. The two modes are orthogonally polarized, and separated by less than the bandwidth of the ˜ 130 fs excitation pulses. The relative amplitudes of the two modes can be controlled by adjusting the polarization and the centre frequency of the excitation beam. Cross-polarized detection of the resonantly scattered light reveals a well-defined relative phase between the modes that is characteristic of their coherence. When the short-pulse excitation is used to coherently excite two modes in a three-hole line-defect (L3) InP microcavity, second-order harmonic radiation is observed due to the interactions of the resonant fields with the second-order nonlinear susceptibility (chi(2)) of the host InP slab. Second-harmonic and sum-frequency generated signals are observed due to the intra- and inter-mode nonlinear mixing of the microcavity fields. When a separate non-resonant pulse is focussed onto an InP microcavity, sum-frequency light is generated conditional to the resonant mode population of the microcavity. The conditionally generated signals can be tuned by tuning the frequency of the non-resonant pulse. All of the results can be explained with reference to the bulk chi(2) properties of the InP slab. While the transient, multi-mode response of the microcavities is harnessed with the short-pulse technique, a continuous wave excitation laser exploits the local-field enhancement intrinsic to these wavelength-scale microcavities. A single-mode InP L3-microcavity with Q = 3,800 is pumped on resonance with a CW laser, and the 2D pattern of far-field second-harmonic radiation is directly imaged. The second

  9. Multi-modes processes for stretched spiral vortex formation

    NASA Astrophysics Data System (ADS)

    Horiuti, Kiyosi

    2004-11-01

    We studied a process for formation of the stretched spiral vortex (Lundgren 1982) in incompressible homogeneous isotropic turbulence. It was shown that multi modes exist for the configuration of alignment between the vorticity vectors along the vortex tube core and the vorticity vector along the sheet which emanates from and wraps around the tube core. A representative one is that generated via a roll-up of the vortex sheet through focusing, in which these two vorticity vectors were parallel. Alternative mechanism for formation of this parallel configuration was through the interaction of two different sheets which were initially placed perpendicular to each other. These two sheets generated a weak circulation and it gradually accumulated to form the tube core region. These two sheets were entrained by the tube core and the spiral sheets emanating from the tube core was formed. The tubes in this mode persisted for a rather long period of time. In another mode, the vorticity vectors along the sheet were in the direction transverse to those along the tube core. It was found that this mode often takes an asymmetric configuration in which the vorticity vectors along one of the sheets were parallel to those along the tube, while the vectors along another sheet were transverse to those along the tube. The configuration in which the vorticity vectors along both sheets were transverse to those along the tube core (Pullin and Lundgren 2001) was rarely found. Intense energy cascade took place with the stretching of the spiral vortex sheets. As the Reynolds number was increased, the frequency of occurrence of the spiral vortex formation increased, and the energy spectrum showed a profile close to the -5/3 law.

  10. Simulated Annealing Inversion of Multi-mode Rayleigh Waves

    NASA Astrophysics Data System (ADS)

    Schmitt, D. R.

    2001-12-01

    Rayleigh-wave velocity dispersion curves provide important constraints on the shear-wave velocity structure from the surface. Most Rayleigh wave studies assume the propagating surface-wave packet is composed solely of the primary Rayleigh mode. However, in near-surface studies higher order Rayleigh wave modes contain a sizable fraction of the propagating surface wave energy; and interference of the various modes complicates analysis. Inversion of Rayleigh wave dispersion curves for structure is further complicated by the inherent nonlinearity of the problem. Simulated annealing is a popular method for solving such problems but has not before been applied to the inversion of multi-mode Rayleigh wave dispersion curves. We applied this method to a near-surface set of Rayleigh waves produced by hammer blows onto the surface of a thick clay layer and recorded by an array 3-component geophones offset from the source from 7-m to 38-m at a 0.5-m spacing. Three strong Rayleigh wave modes were detected over the frequencies from 10-Hz to 80-Hz from the observed traces using a modified slant-stack method. Inversion of the three resulting dispersion curves provided a stable inversion that agreed well with the geologic stratification known from wellbore measurements and coring. In contrast, use of only the primary Rayleigh-wave dispersion curve provided a solution in poorer agreement with the geology despite matching the dispersion curve well. This study suggests that incorporating higher order Rayleigh wave modes yields a more reliable solution for geologic interpretation of near surface structure.

  11. Helical Fiber Amplifier

    DOEpatents

    Koplow, Jeffrey P.; Kliner, Dahy; Goldberg, Lew

    2002-12-17

    A multi-mode gain fiber is provided which affords substantial improvements in the maximum pulse energy, peak power handling capabilities, average output power, and/or pumping efficiency of fiber amplifier and laser sources while maintaining good beam quality (comparable to that of a conventional single-mode fiber source). These benefits are realized by coiling the multimode gain fiber to induce significant bend loss for all but the lowest-order mode(s).

  12. Multi-mode of Four and Six Wave Parametric Amplified Process

    PubMed Central

    Zhu, Dayu; Yang, Yiheng; Zhang, Da; Liu, Ruizhou; Ma, Danmeng; Li, Changbiao; Zhang, Yanpeng

    2017-01-01

    Multiple quantum modes in correlated fields are essential for future quantum information processing and quantum computing. Here we report the generation of multi-mode phenomenon through parametric amplified four- and six-wave mixing processes in a rubidium atomic ensemble. The multi-mode properties in both frequency and spatial domains are studied. On one hand, the multi-mode behavior is dominantly controlled by the intensity of external dressing effect, or nonlinear phase shift through internal dressing effect, in frequency domain; on the other hand, the multi-mode behavior is visually demonstrated from the images of the biphoton fields directly, in spatial domain. Besides, the correlation of the two output fields is also demonstrated in both domains. Our approach supports efficient applications for scalable quantum correlated imaging. PMID:28255163

  13. Multi-mode of Four and Six Wave Parametric Amplified Process

    NASA Astrophysics Data System (ADS)

    Zhu, Dayu; Yang, Yiheng; Zhang, Da; Liu, Ruizhou; Ma, Danmeng; Li, Changbiao; Zhang, Yanpeng

    2017-03-01

    Multiple quantum modes in correlated fields are essential for future quantum information processing and quantum computing. Here we report the generation of multi-mode phenomenon through parametric amplified four- and six-wave mixing processes in a rubidium atomic ensemble. The multi-mode properties in both frequency and spatial domains are studied. On one hand, the multi-mode behavior is dominantly controlled by the intensity of external dressing effect, or nonlinear phase shift through internal dressing effect, in frequency domain; on the other hand, the multi-mode behavior is visually demonstrated from the images of the biphoton fields directly, in spatial domain. Besides, the correlation of the two output fields is also demonstrated in both domains. Our approach supports efficient applications for scalable quantum correlated imaging.

  14. Laser-direct writing of single mode and multi-mode polymer step index waveguide structures for optical backplanes and interconnection assemblies

    NASA Astrophysics Data System (ADS)

    Kruse, Kevin; Middlebrook, Christopher

    2015-01-01

    A laser direct writing (LDW) method is implemented as a cost efficient polymer waveguide (WG) fabrication method for prototyping large substrates for optical backplanes and optical interconnection assemblies. The LDW setup utilizes a 3-axis air-bearing motion platform to reduce WG fabrication error to within ±0.15 μm. A UV laser diode coupled single mode fiber with a focusing lens module is capable of LDW WGs at both multimode (50 μm) and single mode (6 μm) dimensions. Correlation between LDW parameters and fabricated WG dimensions using Dow Corning® OE-4140 UV-Cured Optical Elastomer (ncore = 1.5142, nclad = 1.5064) is discussed theoretically and confirmed experimentally for both applications. A theoretical model is developed and utilized for producing LDW multi-mode (0.04 dB/cm, λ = 850 nm) and single mode (0.55 dB/cm, λ = 1310 nm) WGs. Measured propagation losses of LDW WGs are comparable to losses of photolithographic multi-mode (0.04 dB/cm @ 850 nm) and single mode (0.59 dB/cm @ 1310 nm) WG builds. LDW multi-mode and single mode WG radial bend and crossing losses are evaluated for advanced optical communication channel routing capabilities and do not exhibit significant deviations from photolithographic-manufactured WG device loss.

  15. Characteristics of Single- and Multi-Mode Optical Waveguides.

    DTIC Science & Technology

    1982-04-01

    and R. Ebrahimian , "Propagation constants for step- index fibers of arbitrary cross-section at high frequency," USNC/URSI National Radio Science...Rozalina Ebrahimian , graduate student and research assistant (/15/81 -5/30/81) (M.S., in progress) 10. Mr. Todd Pet, graduate student and research...Mahnad and Rozalina Ebrahimian . A Ph.D. dissertation by Robert L. Holland which deals in part with curvature of channel waveguides is currently in progress.

  16. Comparison of single-/few-/multi-mode 850 nm VCSELs for optical OFDM transmission.

    PubMed

    Kao, Hsuan-Yun; Tsai, Cheng-Ting; Leong, Shan-Fong; Peng, Chun-Yen; Chi, Yu-Chieh; Huang, Jian Jang; Kuo, Hao-Chung; Shih, Tien-Tsorng; Jou, Jau-Ji; Cheng, Wood-Hi; Wu, Chao-Hsin; Lin, Gong-Ru

    2017-07-10

    For high-speed optical OFDM transmission applications, a comprehensive comparison of the homemade multi-/few-/single-transverse mode (MM/FM/SM) vertical cavity surface emitting laser (VCSEL) chips is performed. With microwave probe, the direct encoding of pre-leveled 16-QAM OFDM data and transmission over 100-m-long OM4 multi-mode-fiber (MMF) are demonstrated for intra-datacenter applications. The MM VCSEL chip with the largest emission aperture of 11 μm reveals the highest differential quantum efficiency which provides the highest optical power of 8.67 mW but exhibits the lowest encodable bandwidth of 21 GHz. In contrast, the SM VCSEL chip fabricated with the smallest emission aperture of only 3 μm provides the highest 3-dB encoding bandwidth up to 23 GHz at a cost of slight heat accumulation. After optimization, with the trade-off set between the receiving signal-to-noise ratio (SNR) and bandwidth, the FM VCSEL chip guarantees the highest optical OFDM transmission bit rate of 96 Gbit/s under back-to-back case with its strongest throughput. Among three VCSEL chips, the SM VCSEL chip with nearly modal-dispersion free feature is treated as the best candidate for carrying the pre-leveled 16-QAM OFDM data over 100-m OM4-MMF with same material structure but exhibits different oxide-layer confined gain cross-sections with one another at 80-Gbit/s with the smallest receiving power penalty of 1.77 dB.

  17. Dwell time algorithm for multi-mode optimization in manufacturing large optical mirrors

    NASA Astrophysics Data System (ADS)

    Liu, Zhenyu

    2014-08-01

    CCOS (Computer Controlled Optical Surfacing) is one of the most important method to manufacture optical surface. By controlling the dwell time of a polishing tool on the mirror we can get the desired material removal. As the optical surface becoming larger, traditional CCOS method can't meet the demand that manufacturing the mirror in higher efficiency and precision. This paper presents a new method using multi-mode optimization. By calculate the dwell time map of different tool in one optimization cycle, the larger tool and the small one have complementary advantages and obtain a global optimization for multi tool and multi-processing cycles. To calculate the dwell time of different tool at the same time we use multi-mode dwell time algorithm that based on matrix calculation. With this algorithm we did simulation experiment, the result shows using multi-mode optimization algorithm can improve the efficiency maintaining good precision.

  18. Minimizing influence of multi-modes and dispersion of electromagnetic ultrasonic lamb waves.

    PubMed

    Zhai, Guofu; Jiang, Tao; Kang, Lei; Wang, Shujuan

    2010-12-01

    Electromagnetic ultrasonic (EMU) Lamb waves excited by electromagnetic acoustic transducers (EMATs) possess many advantages in NDT. However, their characteristic multi-modes and dispersion are disadvantageous for inspection and restrict further improvements in their real applications. By deducing the excitation equation of EMU Lamb waves, the primary design parameters of EMATs and the characteristic equation of Lamb waves are combined, and excitation curves based on the excitation equation are plotted to aid the design of EMATs. The excitation characteristic of EMU Lamb waves on different thickness of plates is analyzed according to the excitation curves. The influence of multi-modes of EMU Lamb waves is minimized by choosing reasonable operating points and operating zones to excite a single-mode Lamb wave or multi-mode Lamb waves with identical or approximate propagation velocities. The influence of dispersion is minimized by searching corresponding points whose slope of group velocity tends to zero. The validity of the proposed method is verified by experiments.

  19. Multi-mode TES Bolometer Optimization for the LSPE-SWIPE Instrument

    NASA Astrophysics Data System (ADS)

    Gualtieri, R.; Battistelli, E. S.; Cruciani, A.; de Bernardis, P.; Biasotti, M.; Corsini, D.; Gatti, F.; Lamagna, L.; Masi, S.

    2016-08-01

    In this paper, we explore the possibility of using transition edge sensor (TES) detectors in multi-mode configuration in the focal plane of the Short Wavelength Instrument for the Polarization Explorer (SWIPE) of the balloon-borne polarimeter Large-Scale Polarization Explorer (LSPE) for the Cosmic Microwave Background (CMB) polarization. This study is motivated by the fact that maximizing the sensitivity of TES bolometers, under the augmented background due to the multi-mode design, requires a non-trivial choice of detector parameters. We evaluate the best parameter combination taking into account scanning strategy, noise constraints, saturation power, and operating temperature of the cryostat during the flight.

  20. A coaxially focused multi-mode beam for optical coherence tomography imaging with extended depth of focus (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Yin, Biwei; Liang, Chia-Pin; Vuong, Barry; Tearney, Guillermo J.

    2017-02-01

    Conventional OCT images, obtained using a focused Gaussian beam have a lateral resolution of approximately 30 μm and a depth of focus (DOF) of 2-3 mm, defined as the confocal parameter (twice of Gaussian beam Rayleigh range). Improvement of lateral resolution without sacrificing imaging range requires techniques that can extend the DOF. Previously, we described a self-imaging wavefront division optical system that provided an estimated one order of magnitude DOF extension. In this study, we further investigate the properties of the coaxially focused multi-mode (CAFM) beam created by this self-imaging wavefront division optical system and demonstrate its feasibility for real-time biological tissue imaging. Gaussian beam and CAFM beam fiber optic probes with similar numerical apertures (objective NA≈0.5) were fabricated, providing lateral resolutions of approximately 2 μm. Rigorous lateral resolution characterization over depth was performed for both probes. The CAFM beam probe was found to be able to provide a DOF that was approximately one order of magnitude greater than that of Gaussian beam probe. By incorporating the CAFM beam fiber optic probe into a μOCT system with 1.5 μm axial resolution, we were able to acquire cross-sectional images of swine small intestine ex vivo, enabling the visualization of subcellular structures, providing high quality OCT images over more than a 300 μm depth range.

  1. Sparse reconstruction of blade tip-timing signals for multi-mode blade vibration monitoring

    NASA Astrophysics Data System (ADS)

    Lin, Jun; Hu, Zheng; Chen, Zhong-Sheng; Yang, Yong-Min; Xu, Hai-Long

    2016-12-01

    Severe blade vibrations may reduce the useful life of the high-speed blade. Nowadays, non-contact measurement using blade tip-timing (BTT) technology is becoming promising in blade vibration monitoring. However, blade tip-timing signals are typically under-sampled. How to extract characteristic features of unknown multi-mode blade vibrations by analyzing these under-sampled signals becomes a big challenge. In this paper, a novel BTT analysis method for reconstructing unknown multi-mode blade vibration signals is proposed. The method consists of two key steps. First, a sparse representation (SR) mathematical model for sparse blade tip-timing signals is built. Second, a multi-mode blade vibration reconstruction algorithm is proposed to solve this SR problem. Experiments are carried out to validate the feasibility of the proposed method. The main advantage of this method is its ability to reconstruct unknown multi-mode blade vibration signals with high accuracy. The minimal requirements of probe number are also presented to provide guidelines for BTT system design.

  2. [Development and applications of the extracorporeal control point module on multi-mode medical images].

    PubMed

    Chen, Zhao-Qiu; Zhao, Feng-Ling; Zhu, Jian; Li, Wan-Hu; Fu, Zheng; Hu, Xu-Dong

    2008-07-01

    This paper introduces a display module which can be used on multi-mode medical images. The module has a small size and can be easily used for point-selecting puncture diagnosis and treatment, and registration for image fusion control points.

  3. Review on the Recent Development of Multi-mode Combined Detonation Engine

    NASA Astrophysics Data System (ADS)

    Jin, Le; Fan, Wei; Wang, Ke; Gao, Zhan

    2013-09-01

    In the next few decades, the development of hypersonic aircrafts will be the priority of national defense strategy of many countries, and the significance of the propulsion system applied on the aircraft is self-evident. Hypersonic aircrafts require propulsion devices that can be used independently in a wide range of Mach numbers and flight envelop, however, there have been no such propulsion systems up to now. The multi-mode combined detonation engine, which consists of four modes, is a novel propulsion concept proposed at the beginning of this century for potential application on hypersonic cruise or space access. The multi-mode combined detonation engine is a promising propulsion system which can be used independently in a wide range of Mach numbers and flight envelop. Recently, many countries attach much importance to the research of multi-mode combined detonation engine and great progress has been achieved. This paper attempts to provide an overview of the recent advances in the multi-mode combined detonation engine, and the major progress for each mode is detailed introduced. Nevertheless, there is still a need to pay more attention to the existing problems in the future.

  4. WET-NZ Multi-Mode Wave Energy Converter Advancement Project

    SciTech Connect

    Klure, Justin

    2011-11-01

    Presentation from the 2011 Water Peer Review in which the principal investigator discussed the next steps to verify a multi-mode functionality of the WET-NZ device. This included overview of the approaches taken to perform wave tank testing, open ocean deployment, synthesis and analysis.

  5. A robo-pigeon based on an innovative multi-mode telestimulation system.

    PubMed

    Yang, Junqing; Huai, Ruituo; Wang, Hui; Lv, Changzhi; Su, Xuecheng

    2015-01-01

    In this paper, we describe a new multi-mode telestimulation system for brain-microstimulation for the navigation of a robo-pigeon, a new type of bio-robot based on Brain-Computer Interface (BCI) techniques. The multi-mode telestimulation system overcomes neuron adaptation that was a key shortcoming of the previous single-mode stimulation by the use of non-steady TTL biphasic pulses accomplished by randomly alternating pulse modes. To improve efficiency, a new behavior model ("virtual fear") is proposed and applied to the robo-pigeon. Unlike the previous "virtual reward" model, the "virtual fear" behavior model does not require special training. The performance and effectiveness of the system to alleviate the adaptation of neurons was verified by a robo-pigeon navigation test, simultaneously confirming the practicality of the "virtual fear" behavioral model.

  6. Finite element analysis for the inhibition of electromagnetic acoustic testing (EMAT) Lamb waves multi-modes

    NASA Astrophysics Data System (ADS)

    Liu, Suzhen; Zhang, Yanwei; Zhang, Chuang; Yang, Qingxin

    2017-02-01

    Lamb waves are widely used in nondestructive testing (NDT) and structural health monitoring (SHM) for its obvious advantages, such as good directionality, longer-range propagation and lower loss etc. However, it is difficult to analysis and to interpret the echo signals because of its multi-modes and dispersion. In this paper, the properties of single-mode Lamb waves which were excited by double EMAT were studied based on the principles of multi-modes and the characteristics of wave structure. Simulation results show that the double transducer excitation structure can stimulate single-mode Lamb waves and eliminate the extra modes, which are produced by modal conversion at ends of the specimen. The single-mode excitation of Lamb waves is beneficial to reduce the difficulty of signal processing and provide reliable information to locate the defect. The researches in this paper can be used as a theoretical basis to design double transducer excitation system.

  7. Evolution of multi-mode operation in vertical-external-cavity surface-emitting lasers.

    PubMed

    Wichmann, Matthias; Shakfa, Mohammad Khaled; Zhang, Fan; Heinen, Bernd; Scheller, Maik; Rahimi-Iman, Arash; Stolz, Wolfgang; Moloney, Jerome V; Koch, Stephan W; Koch, Martin

    2013-12-30

    The longitudinal multi-mode emission in a vertical-external-cavity surface-emitting laser is investigated using both single shot streak camera measurements and interferometric measurement techniques. For this, the laser is operated in the single- and two-color emission regime using both an etalon and a free-running configuration without etalon, respectively. The laser emission is analyzed with respect to pump power and output coupling losses for a long and for a short resonator. We observe a steep increase of emission bandwidth close to the laser threshold and monitor the transition between longitudinal single- and multi-mode operation. Additionally, the results indicate that a stable two-color operation is related to a sufficiently high number of oscillating longitudinal modes within each color.

  8. Multi-Mode Analysis of Dual Ridged Waveguide Systems for Material Characterization

    DTIC Science & Technology

    2015-09-17

    Ross-Weir xi MULTI-MODE ANALYSIS OF DUAL RIDGED WAVEGUIDE SYSTEMS FOR MATERIAL CHARACTERIZATION I. Introduction 1.1 Introduction Electromagnetic material...machined or altered in some way in order to fit into the electromagnetic testing device (e.g., waveguide). Destructive techniques often have the...accurately model new designs such as antennas and absorbing coatings. While many numerous techniques exist in the microwave spectrum , their

  9. System Framework for a Multi-Band, Multi-Mode Software Defined Radio

    DTIC Science & Technology

    2014-06-01

    being developed for next- generation telemetry applications. The system framework consists of a multi-band front-end (MBFE), a multi-mode digital... telemetry waveforms. Finally, the C2 consists of the software and hardware components for system configuration, control and status. The MBFE is...a-chip (SoC) technology. Design methodologies, hardware architectures, and system tradeoffs are highlighted to meet next-generation telemetry

  10. Unconventional geometric logic gate in a strong-driving-assisted multi-mode cavity

    NASA Astrophysics Data System (ADS)

    Pan, Chang-Ning; Yang, Di-Wu; Zhao, Xue-Hui; Fang, Mao-Fa

    2010-08-01

    We propose a scheme to implement an unconventional geometric logic gate separately in a two-mode cavity and a multi-mode cavity assisted by a strong classical driving field. The effect of the cavity decay is included in the investigation. The numerical calculation is carried out, and the result shows that our scheme is more tolerant to cavity decay than the previous one because the time consumed for finishing the logic gate is doubly reduced.

  11. Multi-mode Intravascular RF Coil for MRI-guided Interventions

    PubMed Central

    Kurpad, Krishna N.; Unal, Orhan

    2011-01-01

    Purpose To demonstrate the feasibility of using a single intravascular RF probe connected to the external MRI system via a single coaxial cable to perform active tip tracking and catheter visualization, and high SNR intravascular imaging. Materials and Methods A multi-mode intravascular RF coil was constructed on a 6F balloon catheter and interfaced to a 1.5T MRI scanner via a decoupling circuit. Bench measurements of coil impedances were followed by imaging experiments in saline and phantoms. Results The multi-mode coil behaves as an inductively-coupled transmit coil. Forward looking capability of 6mm is measured. Greater than 3-fold increase in SNR compared to conventional imaging using optimized external coil is demonstrated. Simultaneous active tip tracking and catheter visualization is demonstrated. Conclusions It is feasible to perform 1) active tip tracking, 2) catheter visualization, and 3) high SNR imaging using a single multi-mode intravascular RF coil that is connected to the external system via a single coaxial cable. PMID:21448969

  12. Semi-quartic force fields retrieved from multi-mode expansions: Accuracy, scaling behavior, and approximations

    SciTech Connect

    Ramakrishnan, Raghunathan; Rauhut, Guntram

    2015-04-21

    Semi-quartic force fields (QFF) rely on a Taylor-expansion of the multi-dimensional Born-Oppenheimer potential energy surface (PES) and are frequently used within the calculation of anharmonic vibrational frequencies based on 2nd order vibrational perturbation theory (VPT2). As such they are usually determined by differentiation of the electronic energy with respect to the nuclear coordinates. Alternatively, potential energy surfaces can be expanded in terms of multi-mode expansions, which typically do not require any derivative techniques. The computational effort to retrieve QFF from size-reduced multi-mode expansions has been studied and has been compared with standard Taylor-expansions. As multi-mode expansions allow for the convenient introduction of subtle approximations, these will be discussed in some detail. In addition, a preliminary study about the applicability of a generalized Duschinsky transformation to QFFs is provided. This transformation allows for the efficient evaluation of VPT2 frequencies of isotopologues from the PES of the parent compound and thus avoids the recalculation of PESs in different axes systems.

  13. Multi-mode passive piezoelectric shunt damping by means of matrix inequalities

    NASA Astrophysics Data System (ADS)

    Berardengo, M.; Manzoni, S.; Conti, A. M.

    2017-09-01

    This paper deals with the use of matrix inequalities for the aim of multi-modal piezoelectric shunt damping. The paper shows that the shunt impedance can be seen as a controller in a state space model of the electro-mechanical system; this makes it possible to use the mentioned approach to find the layout of the impedance for different kinds of control problems. The particular focus is on passive multi-mode vibration control with the aim of finding the optimal shunt impedance among the passive and realizable candidates. The proposed method overcomes most of the problems related to the development of the optimal shunt electrical network, which arise when using the most common shunt design strategies for multi-mode control. The results were validated experimentally and compared to well-established methods for multi-mode shunt damping. The proposed method proved to be effective, and the results demonstrate the capability of the matrix inequality approach to provide attenuation levels that are usually higher than those from the reference methods.

  14. Optical characterisation and analysis of multi-mode pixels for use in future far infrared telescopes

    NASA Astrophysics Data System (ADS)

    McCarthy, Darragh; Trappe, Neil; Murphy, J. Anthony; Doherty, Stephen; Gradziel, Marcin; O'Sullivan, Créidhe; Audley, Michael D.; de Lange, Gert; van der Vorst, Maarten

    2016-07-01

    In this paper we present the development and verification of feed horn simulation code based on the mode- matching technique to simulate the electromagnetic performance of waveguide based structures of rectangular cross-section. This code is required to model multi-mode pyramidal horns which may be required for future far infrared (far IR) space missions where wavelengths in the range of 30 to 200 µm will be analysed. Multi-mode pyramidal horns can be used effectively to couple radiation to sensitive superconducting devices like Kinetic Inductance Detectors (KIDs) or Transition Edge Sensor (TES) detectors. These detectors could be placed in integrating cavities (to further increase the efficiency) with an absorbing layer used to couple to the radiation. The developed code is capable of modelling each of these elements, and so will allow full optical characterisation of such pixels and allow an optical efficiency to be calculated effectively. As the signals being measured at these short wavelengths are at an extremely low level, the throughput of the system must be maximised and so multi-mode systems are proposed. To this end, the focal planes of future far IR missions may consist of an array of multi-mode rectangular feed horns feeding an array of, for example, TES devices contained in individual integrating cavities. Such TES arrays have been fabricated by SRON Groningen and are currently undergoing comprehensive optical, electrical and thermal verification. In order to fully understand and validate the optical performance of the receiver system, it is necessary to develop comprehensive and robust optical models in parallel. We outline the development and verification of this optical modelling software by means of applying it to a representative multi-mode system operating at 150 GHz in order to obtain sufficiently short execution times so as to comprehensively test the code. SAFARI (SPICA FAR infrared Instrument) is a far infrared imaging grating spectrometer

  15. Fiber optic applications for laser polarized targets

    SciTech Connect

    Cummings, W.J.; Kowalczyk, R.S.

    1997-10-01

    For the past two years, the laser polarized target group at Argonne has been used multi-mode fiber optic patch cords for a variety of applications. In this paper, the authors describe the design for transporting high power laser beams with optical fibers currently in use at IUCF.

  16. Predictive coarse-graining

    NASA Astrophysics Data System (ADS)

    Schöberl, Markus; Zabaras, Nicholas; Koutsourelakis, Phaedon-Stelios

    2017-03-01

    We propose a data-driven, coarse-graining formulation in the context of equilibrium statistical mechanics. In contrast to existing techniques which are based on a fine-to-coarse map, we adopt the opposite strategy by prescribing a probabilistic coarse-to-fine map. This corresponds to a directed probabilistic model where the coarse variables play the role of latent generators of the fine scale (all-atom) data. From an information-theoretic perspective, the framework proposed provides an improvement upon the relative entropy method [1] and is capable of quantifying the uncertainty due to the information loss that unavoidably takes place during the coarse-graining process. Furthermore, it can be readily extended to a fully Bayesian model where various sources of uncertainties are reflected in the posterior of the model parameters. The latter can be used to produce not only point estimates of fine-scale reconstructions or macroscopic observables, but more importantly, predictive posterior distributions on these quantities. Predictive posterior distributions reflect the confidence of the model as a function of the amount of data and the level of coarse-graining. The issues of model complexity and model selection are seamlessly addressed by employing a hierarchical prior that favors the discovery of sparse solutions, revealing the most prominent features in the coarse-grained model. A flexible and parallelizable Monte Carlo - Expectation-Maximization (MC-EM) scheme is proposed for carrying out inference and learning tasks. A comparative assessment of the proposed methodology is presented for a lattice spin system and the SPC/E water model.

  17. Fiber

    MedlinePlus

    ... 2016:chap 213. National Research Council. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). The National Academies Press. ...

  18. Direct measurement of the Wigner characteristic function of an arbitrary multi-mode entangled traveling field

    NASA Astrophysics Data System (ADS)

    Xu, Yejun; Liang, Xiudong; Cheng, Jianming; Tai, Yunjiao; Song, Jun

    2014-03-01

    We present a simple proposal to measure arbitrary multi-mode entangled traveling field state based on a Mach-Zehnder interferometer in theory. Our method directly yields the characteristic function of the Wigner function without a demanding data analysis and can be easily carried out by recent technological advances. Especially, it is a very effective reconstruction proposal for an entangled traveling field with a small number of modes from the experimental point of view. We demonstrate the scheme for the example of a two-mode squeezed vacuum state to illustrate how similar the reconstructed state is to the ideal one via controlling the values of phase shifts.

  19. Rate-equation model for multi-mode semiconductor lasers with spatial hole burning.

    PubMed

    Lenstra, Daan; Yousefi, Mirvais

    2014-04-07

    We present a set of rate equations for the modal amplitudes and carrier-inversion moments that describe the deterministic multi-mode dynamics of a semiconductor laser due to spatial hole burning. Mutual interactions among the lasing modes, induced by high- frequency modulations of the carrier distribution, are included by carrier-inversion moments for which rate equations are given as well. We derive the Bogatov effect of asymmetric gain suppression in semiconductor lasers and illustrate the potential of the model for a two and three-mode laser by numerical and analytical methods.

  20. Diode-Pumped Narrow Linewidth Multi-kW Metalized Yb Fiber Amplifier

    DTIC Science & Technology

    2016-10-01

    multi-kW Yb fiber amplifier in a bi-directional pumping configuration. Each pump outputs 2 kW in a 200 µm, 0.2 NA multi-mode fiber. Gold -coated...fiber for 20 dB total pump absorption. The fiber has gold coating outside of its F-doped outerclad. Gold coating can operate at significantly higher

  1. Backward Amplification and Beam Cleanup of a Raman Fiber Laser Oscillator using a Multi-Mode Graded Index Fiber Amplifier

    DTIC Science & Technology

    2006-03-01

    is approximately 1x10 -13 m/W, it is then possible to use 20 eff facth R eff A p P g L ≈ (20) to make a threshold calculation for SRS in the...measurements to the equation of a Gaussian beam shown below 1/ 222 R 0R 2 0R ( ) 1 z Mw z w w λ π ⎡ ⎤⎛ ⎞ ⎢ ⎥= + ⎜ ⎟ ⎢ ⎥⎝ ⎠⎣ ⎦ (21) using a nonlinear...direction of propagation, R ( )w z is the radius of the beam at z, and λ is the wavelength of the propagating beam (10). The code used for Mathematica is

  2. Damage classification of pipelines under water flow operation using multi-mode actuated sensing technology

    NASA Astrophysics Data System (ADS)

    Lee, Changgil; Park, Seunghee

    2011-11-01

    In a structure, several types of damage can occur, ranging from micro-cracking to corrosion or loose bolts. This makes identifying the damage difficult with a single mode of sensing. Therefore, a multi-mode actuated sensing system is proposed based on a self-sensing circuit using a piezoelectric sensor. In self-sensing-based multi-mode actuated sensing, one mode provides a wide frequency-band structural response from the self-sensed impedance measurement and the other mode provides a specific frequency-induced structural wavelet response from the self-sensed guided wave measurement. In this experimental study, a pipeline system under water flow operation was examined to verify the effectiveness and robustness of the proposed structural health monitoring approach. Different types of structural damage were inflicted artificially on the pipeline system. To classify the multiple types of structural damage, supervised learning-based statistical pattern recognition was implemented by composing a three-dimensional space using the damage indices extracted from the impedance and guided wave features as well as temperature variations. For a more systematic damage classification, several control parameters were optimized to determine an optimal decision boundary for the supervised learning-based pattern recognition. Further research issues are also discussed for real-world implementations of the proposed approach.

  3. A Multi-Mode Blade Damping Control using Shunted Piezoelectric Transducers with Active Feedback Structure

    NASA Technical Reports Server (NTRS)

    Choi, Benjamin; Morrison, Carlos; Min, James

    2009-01-01

    The Structural Dynamics and. Mechanics branch (RXS) is developing smart adaptive structures to improve fan blade damping at resonances using piezoelectric (PE) transducers. In this presentation, only one shunted PE transducer was used to demonstrate active control of multi-mode blade resonance damping on a titanium alloy (Ti-6A1-4V) flat plate model, regardless of bending, torsion, and 2-stripe modes. This work would have a significant impact on the conventional passive shunt damping world because the standard feedback control design tools can now be used to design and implement electric shunt for vibration control. In other words, the passive shunt circuit components using massive inductors and. resistors for multi-mode resonance control can be replaced with digital codes. Furthermore, this active approach with multi patches can simultaneously control several modes in the engine operating range. Dr. Benjamin Choi presented the analytical and experimental results from this work at the Propulsion-Safety and. Affordable Readiness (P-SAR) Conference in March, 2009.

  4. TeraSCREEN: multi-frequency multi-mode Terahertz screening for border checks

    NASA Astrophysics Data System (ADS)

    Alexander, Naomi E.; Alderman, Byron; Allona, Fernando; Frijlink, Peter; Gonzalo, Ramón; Hägelen, Manfred; Ibáñez, Asier; Krozer, Viktor; Langford, Marian L.; Limiti, Ernesto; Platt, Duncan; Schikora, Marek; Wang, Hui; Weber, Marc Andree

    2014-06-01

    The challenge for any security screening system is to identify potentially harmful objects such as weapons and explosives concealed under clothing. Classical border and security checkpoints are no longer capable of fulfilling the demands of today's ever growing security requirements, especially with respect to the high throughput generally required which entails a high detection rate of threat material and a low false alarm rate. TeraSCREEN proposes to develop an innovative concept of multi-frequency multi-mode Terahertz and millimeter-wave detection with new automatic detection and classification functionalities. The system developed will demonstrate, at a live control point, the safe automatic detection and classification of objects concealed under clothing, whilst respecting privacy and increasing current throughput rates. This innovative screening system will combine multi-frequency, multi-mode images taken by passive and active subsystems which will scan the subjects and obtain complementary spatial and spectral information, thus allowing for automatic threat recognition. The TeraSCREEN project, which will run from 2013 to 2016, has received funding from the European Union's Seventh Framework Programme under the Security Call. This paper will describe the project objectives and approach.

  5. A multi-mode sensing system for corrosion detection using piezoelectric wafer active sensors

    NASA Astrophysics Data System (ADS)

    Yu, Lingyu; Giurgiutiu, Victor; Pollock, Patrick

    2008-03-01

    As an emerging technology for in-situ damage detection and nondestructive evaluation, structural health monitoring with active sensors (active SHM) plays as a promising candidate for the pipeline inspection and diagnosis. Piezoelectric wafer active sensor (PWAS), as an active sensing device, can be permanently attached to the structure to interrogate it at will and can operate in propagating wave mode or electromechanical impedance mode. Its small size and low cost (about $10 each) make itself a potential and unique technology for in-situ SHM application. The objective of the research in this paper is to develop a permanently installed in-situ "multi-mode" sensing system for the corrosion monitoring and prediction of critical pipeline systems. Such a system is used during in-service period, recording and monitoring the changes of the pipelines over time, such as corrosion, wall thickness, etc. Having the real-time data available, maintenance strategies based on these data can then be developed to ensure a safe and less expensive operation of the pipeline systems. After a detailed review of PWAS SHM methods, including ultrasonic, impedance, and thickness measurement, we introduce the concept of PWAS-based multi-mode sensing approach for corrosion detection in pipelines. Particularly, we investigate the potential for using PWAS waves for in thickness mode experimentally. Finally, experiments are conducted to verify the corrosion detection ability of the PWAS network in both metallic plate and pipe in a laboratory setting. Results show successful corrosion localization in both tests.

  6. Integration of geospatial multi-mode transportation Systems in Kuala Lumpur

    NASA Astrophysics Data System (ADS)

    Ismail, M. A.; Said, M. N.

    2014-06-01

    Public transportation serves people with mobility and accessibility to workplaces, health facilities, community resources, and recreational areas across the country. Development in the application of Geographical Information Systems (GIS) to transportation problems represents one of the most important areas of GIS-technology today. To show the importance of GIS network analysis, this paper highlights the determination of the optimal path between two or more destinations based on multi-mode concepts. The abstract connector is introduced in this research as an approach to integrate urban public transportation in Kuala Lumpur, Malaysia including facilities such as Light Rapid Transit (LRT), Keretapi Tanah Melayu (KTM) Komuter, Express Rail Link (ERL), KL Monorail, road driving as well as pedestrian modes into a single intelligent data model. To assist such analysis, ArcGIS's Network Analyst functions are used whereby the final output includes the total distance, total travelled time, directional maps produced to find the quickest, shortest paths, and closest facilities based on either time or distance impedance for multi-mode route analysis.

  7. A baseband LPF for GSM, TD-SCDMA and WCDMA multi-mode transmitters

    NASA Astrophysics Data System (ADS)

    Yongchang, Yu; Kefeng, Han; Lifang, Wang; Xi, Tan; Hao, Min

    2011-02-01

    This paper describes a low-pass reconfigurable baseband filter for GSM, TD-SCDMA and WCDMA multi-mode transmitters. To comply with 3GPP emission mask and limit TX leakage at the RX band, the out-of-band noise performance is optimized. Due to the distortion caused by the subthreshold leakage current of the switches used in capacitor array, a capacitor bypass technique is proposed to improve the filter's linearity. An automatic frequency tuning circuit is adopted to compensate the cut-off frequency variation. Simulation results show that the filter achieves an in-band input-referred third-order intercept point (IIP3) of 47 dBm at 1.2-V power supply and the out-of-band noise can meet TX SAW-less requirement for WCDMA & TD-SCDMA. The baseband filter incorporates -40 to 0 dB programmable gain control that is accurately variable in 0.5 dB steps. The filter's cut-off frequency can be reconfigured for GSM/TD-SCDMA/WCDMA multi-mode transmitter. The implemented baseband filter draws 3.6 mA from a 1.2-V supply in a 0.13 μm CMOS process.

  8. Multi-mode vibronic interactions in the five lowest electronic states of the fluorobenzene radical cation

    NASA Astrophysics Data System (ADS)

    Bâldea, Ioan; Franz, Jan; Szalay, Péter G.; Köppel, Horst

    2006-10-01

    The multi-mode vibronic interactions between the five lowest electronic states of the fluorobenzene radical cation are investigated theoretically, based on ab initio electronic structure data, and employing the linear vibronic coupling model. Low-energy conical intersections, and strong vibronic couplings are found to prevail within the set of X˜-A˜ and B˜-C˜-D˜ cationic states, while the interactions between these two sets of states are found to be rather weak (owing to high-energy conical intersections). The overall intensity distribution of the experimental photoelectron spectrum, as well as the line positions observed in the MATI spectrum, are well reproduced. The vibronic interactions in the X˜-A˜ states are found to be a replica of the multi-mode dynamical Jahn-Teller effect in the parent system, the XE ground state of the benzene radical cation. Ultrafast internal conversion processes within the electronic manifolds in question demonstrate the strength of the nonadiabatic coupling effects and complement the analogous findings for the electronic spectra. The implications for the fluorescence dynamics of the fluorobenzene radical cation are discussed.

  9. Characteristics and reliability of high power multi-mode InGaAs strained quantum well single emitters with CW output powers of over 5W

    NASA Astrophysics Data System (ADS)

    Sin, Yongkun; Presser, Nathan; Mason, Maribeth; Moss, Steven C.

    2006-02-01

    High-power multi-mode broad area InGaAs strained quantum well (QW) single emitters (λ ~ 920-980nm) have been mainly used for industrial applications. Recently, these broad area lasers with CW output powers >5W have also found applications in communications as pump lasers for Er-Yb co-doped fiber amplifiers. This application requires very demanding characteristics including higher reliability than industrial applications. In contrast to 980nm single mode InGaAs strained QW lasers that are widely employed in both terrestrial and submarine applications, the fact that multimode lasers have never been used in optical communications necessitates careful study of these lasers. We report investigations of performance characteristics, reliability, and failure modes of high-power multi-mode single emitters. The lasers studied were broad area strained InGaAs-GaAs single QW lasers grown either by MOCVD or MBE. Typical apertures were around 100μm wide and cavity lengths were <=4.2mm. AR-HR coated laser diode chips were mounted on carriers with junction down configuration to reduce thermal impedance. Laser thresholds were <=453mA at RT. At 6A injection current typical CW output powers were over 5W at 25°C with wall-plug efficiency of ~60%. Characteristics measured included thermal impedance and optical beam profiles that are critical in understanding performance and reliability. Automatic current control burn-in tests with different stress conditions were performed and log (I)-V characteristics were measured at RT to correlate degradation in optical output power and an increase in trap density estimated from the 2κ•T term in bulk recombination current. We also report initial analysis of lifetest results and failure modes from these lasers.

  10. Multi-Mode Lamb Wave Arrival Time Extraction for Improved Tomographic Reconstruction

    SciTech Connect

    Hinders, Mark K.; Hou Jidong; Leonard, Kevin R.

    2005-04-09

    An ultrasonic signal processing technique is applied to multi-mode arrival time estimation from Lamb waveforms. The basic tool is a simplified time-scale projection called a dynamic wavelet fingerprint (DWFP) which enables direct observation of the variation of features of interest in non-stationary ultrasonic signals. The DWFP technique was used to automatically detect and evaluate each candidate through-transmitted Lamb mode. The area of the dynamic wavelet fingerprint was then used as a feature to distinguish false modes caused by noise and other interference from the true modes of interest. The set of estimated arrival times were then used as inputs for tomographic reconstruction. The Lamb wave tomography images generated with these estimated arrival times were able to indicate different defects in aluminum plates.

  11. Multi-mode sliding mode control for precision linear stage based on fixed or floating stator.

    PubMed

    Fang, Jiwen; Long, Zhili; Wang, Michael Yu; Zhang, Lufan; Dai, Xufei

    2016-02-01

    This paper presents the control performance of a linear motion stage driven by Voice Coil Motor (VCM). Unlike the conventional VCM, the stator of this VCM is regulated, which means it can be adjusted as a floating-stator or fixed-stator. A Multi-Mode Sliding Mode Control (MMSMC), including a conventional Sliding Mode Control (SMC) and an Integral Sliding Mode Control (ISMC), is designed to control the linear motion stage. The control is switched between SMC and IMSC based on the error threshold. To eliminate the chattering, a smooth function is adopted instead of a signum function. The experimental results with the floating stator show that the positioning accuracy and tracking performance of the linear motion stage are improved with the MMSMC approach.

  12. Method and apparatus for controlling a powertrain system including a multi-mode transmission

    DOEpatents

    Hessell, Steven M.; Morris, Robert L.; McGrogan, Sean W.; Heap, Anthony H.; Mendoza, Gil J.

    2015-09-08

    A powertrain including an engine and torque machines is configured to transfer torque through a multi-mode transmission to an output member. A method for controlling the powertrain includes employing a closed-loop speed control system to control torque commands for the torque machines in response to a desired input speed. Upon approaching a power limit of a power storage device transferring power to the torque machines, power limited torque commands are determined for the torque machines in response to the power limit and the closed-loop speed control system is employed to determine an engine torque command in response to the desired input speed and the power limited torque commands for the torque machines.

  13. Optical fibre sensors based on multi-mode fibres and MIMO signal processing: an experimental approach

    NASA Astrophysics Data System (ADS)

    Ahrens, Andreas; Sandmann, Andre; Bremer, Kort; Roth, Bernhard; Lochmann, Steffen

    2015-09-01

    In this paper multiple-input multiple-output (MIMO) signal processing is investigated for fibre optic sensor applications. A (2 × 2) MIMO implementation is realized by using lower-order and higher-order mode groups of a graded-index (GI) multi-mode fibre (MMF) as separate transmission channels. A micro-bending pressure sensor changes these separate transmission characteristics and introduces additional crosstalk. By observing the weight-factors of the MIMO system the amount of load applied was determined. Experiments verified a good correlation between the change of the MIMO weight coefficients and the load applied to the sensor and thus verified that MIMO signal processing can beneficially be used for fibre optic sensor applications.

  14. A nonlinear multi-mode wideband piezoelectric vibration-based energy harvester using compliant orthoplanar spring

    SciTech Connect

    Dhote, Sharvari Zu, Jean; Zhu, Yang

    2015-04-20

    In this paper, a nonlinear wideband multi-mode piezoelectric vibration-based energy harvester (PVEH) is proposed based on a compliant orthoplanar spring (COPS), which has an advantage of providing multiple vibration modes at relatively low frequencies. The PVEH is made of a tri-leg COPS flexible structure, where three fixed-guided beams are capable of generating strong nonlinear oscillations under certain base excitation. A prototype harvester was fabricated and investigated through both finite-element analysis and experiments. The frequency response shows multiple resonance which corresponds to a hardening type of nonlinear resonance. By adding masses at different locations on the COPS structure, the first three vibration modes are brought close to each other, where the three hardening nonlinear resonances provide a wide bandwidth for the PVEH. The proposed PVEH has enhanced performance of the energy harvester in terms of a wide frequency bandwidth and a high-voltage output under base excitations.

  15. Multi-mode sliding mode control for precision linear stage based on fixed or floating stator

    NASA Astrophysics Data System (ADS)

    Fang, Jiwen; Long, Zhili; Wang, Michael Yu; Zhang, Lufan; Dai, Xufei

    2016-02-01

    This paper presents the control performance of a linear motion stage driven by Voice Coil Motor (VCM). Unlike the conventional VCM, the stator of this VCM is regulated, which means it can be adjusted as a floating-stator or fixed-stator. A Multi-Mode Sliding Mode Control (MMSMC), including a conventional Sliding Mode Control (SMC) and an Integral Sliding Mode Control (ISMC), is designed to control the linear motion stage. The control is switched between SMC and IMSC based on the error threshold. To eliminate the chattering, a smooth function is adopted instead of a signum function. The experimental results with the floating stator show that the positioning accuracy and tracking performance of the linear motion stage are improved with the MMSMC approach.

  16. Design of a Multi-mode Flight Deck Decision Support System for Airborne Conflict Management

    NASA Technical Reports Server (NTRS)

    Barhydt, Richard; Krishnamurthy, Karthik

    2004-01-01

    NASA Langley has developed a multi-mode decision support system for pilots operating in a Distributed Air-Ground Traffic Management (DAG-TM) environment. An Autonomous Operations Planner (AOP) assists pilots in performing separation assurance functions, including conflict detection, prevention, and resolution. Ongoing AOP design has been based on a comprehensive human factors analysis and evaluation results from previous human-in-the-loop experiments with airline pilot test subjects. AOP considers complex flight mode interactions and provides flight guidance to pilots consistent with the current aircraft control state. Pilots communicate goals to AOP by setting system preferences and actively probing potential trajectories for conflicts. To minimize training requirements and improve operational use, AOP design leverages existing alerting philosophies, displays, and crew interfaces common on commercial aircraft. Future work will consider trajectory prediction uncertainties, integration with the TCAS collision avoidance system, and will incorporate enhancements based on an upcoming air-ground coordination experiment.

  17. Ultra-Wideband Massive MIMO Communications Using Multi-mode Antennas

    NASA Astrophysics Data System (ADS)

    Hoeher, P. A.; Manteuffel, D.; Doose, N.; Peitzmeier, N.

    2017-08-01

    An ultra-wideband system design is presented which supports wireless internet access and similar short-range applications with data rates of the order of 100 Gbps. Unlike concurrent work exploring the 60 GHz regime and beyond for this purpose, our focus is on the 6.0 -8.5 GHz frequency band. Hence, a bandwidth efficiency of about 50 bps/Hz is necessary. This sophisticated goal is targeted by employing two key enabling techniques: massive MIMO communications in conjunction with multi-mode antennas. This concept is suitable both for small-scale terminals like smartphones, as well as for powerful access points. Compared to millimeter wave and THz band communications, the 6.0 -8.5 GHz frequency band offers more robustness in NLOS scenarios and is more mature with respect to system components.

  18. Development of the multi-mode external lighting system for aircraft (M2ESA)

    NASA Astrophysics Data System (ADS)

    Martin, John J.

    2005-08-01

    This paper documents the development of the Multi-Mode External Lighting System for Aircraft (M2ESA), a solid-state near-IR and visible light emitting diode-based programmable system designed to replace existing incandescent navigation lights on the exterior of military aircraft, and tailored for use with night vision goggles. Integrated systems of optics, electronics and mechanical structures were designed that were compatible with legacy aircraft systems, and which thus conformed to rigid configuration requirements and severe volume constraints. The genesis of the concept, evolution and general architecture of the system, top-level performance and environmental requirements, integration on the designated aircraft platform (the F-15), and general results of flight demonstration assessments are described.

  19. A multi-mode manipulator display system for controlling remote robotic systems

    NASA Technical Reports Server (NTRS)

    Massimino, Michael J.; Meschler, Michael F.; Rodriguez, Alberto A.

    1994-01-01

    The objective and contribution of the research presented in this paper is to provide a Multi-Mode Manipulator Display System (MMDS) to assist a human operator with the control of remote manipulator systems. Such systems include space based manipulators such as the space shuttle remote manipulator system (SRMS) and future ground controlled teleoperated and telescience space systems. The MMDS contains a number of display modes and submodes which display position control cues position data in graphical formats, based primarily on manipulator position and joint angle data. Therefore the MMDS is not dependent on visual information for input and can assist the operator especially when visual feedback is inadequate. This paper provides descriptions of the new modes and experiment results to date.

  20. EMTP modeling of electromagnetic transients in multi-mode coaxial cables by finite sections

    SciTech Connect

    Meredith, R.J.

    1997-01-01

    This paper introduces a way of modeling electromagnetic propagation in conductive materials, termed the method of finite sections. It addresses the issues of modeling frequency-dependent impedances and frequency-dependent coupling of conductors. Its use is demonstrated by application to transient modeling of a multi-mode coaxial cable system in the Electromagnetic Transients Program (EMTP), a situation which currently eludes accurate representation. In addition to its use in modeling coaxial cables, the method is applicable to modeling of overhead lines, pipe-type cables, transformer cores and walls, lightning arrestors and other situations in which sufficient planar or cylindrical symmetry exists. The method provides the only accurate EMTP means of modeling wave propagation in non-linear resistive and/or inductive conductors.

  1. Generation and entanglement of multi-dimensional multi-mode coherent fields in cavity QED

    NASA Astrophysics Data System (ADS)

    Maleki, Y.

    2016-11-01

    We introduce generalized multi-mode superposition of multi-dimensional coherent field states and propose a generation scheme of such states in a cavity QED scenario. An appropriate encoding of information on these states is employed, which maps the states to the Hilbert space of some multi-qudit states. The entanglement of these states is characterized based on such proper encodings. A detailed study of entanglement in general multi-qudit coherent states is presented, and in addition to establishing some explicit expressions for quantifying entanglement of such systems, several important features of entanglement in these system states are exposed. Furthermore, the effects of both cavity decay and channel noise on these system states are studied and their properties are illustrated.

  2. [Study on CO2 measurement using tunable multi-mode diode laser absorption spectroscopy].

    PubMed

    Gao, Guang-Zhen; Chen, Bao-Xue; Hu, Bo; Long, Xiu-Hui; Li, Ai-Ping; Li, Rong

    2013-12-01

    Tunable diode laser absorption spectroscopy (TDLAS) technology is a kind of fast time response, large-range, continuous on-line monitoring gas detection technique. It is the mainstream technology of gas detection. In this paper the multimode laser diode was used as light source. Multi-mode laser combined with correlation spectroscopy can improve the test reliability and stability. It can also conquer the problem of the central wavelength change of the single mode diode laser due to thermal or mechanical fluctuations in durable working process. A FP laser was used as the light source in this research. A multi-mode diode laser system based on correlation spectroscopy and wavelength modulation spectroscopy (TMDL-COSPEC-WMS) was used to measure carbon dioxide in ambient air around 1 570 nm. The carbon dioxide concentrations were derived from the relationship between the normalized WMS-2f signal peak heights of the measurement and reference signals which selected based on high signal to noise ratio and correlation coefficient. All measurements were performed with controlled carbon dioxide and nitrogen mixtures in which carbon dioxide concentrations range from 0. 6% to 30%. The calculation results showed that there was a high linear relationship between the measured and actual carbon dioxide concentration, the linearity was 0. 998 7 and the fitted slope was 1. 061+/-0. 016 8 respectively over the tested range. A detection limit of 335 ppm m was achieved. The standard deviation of 0. 036 7% was achieved using 20 successive measurements with each measurement time taking approximately 10 s during 20 minutes, which demonstrated good stability of the system. Good agreements between the measurements of the system and actual values confirm the accuracy and potential utility of the system for carbon dioxide detection.

  3. A multi-mode shock tube for investigation of blast-induced traumatic brain injury.

    PubMed

    Reneer, Dexter V; Hisel, Richard D; Hoffman, Joshua M; Kryscio, Richard J; Lusk, Braden T; Geddes, James W

    2011-01-01

    Blast-induced mild traumatic brain injury (bTBI) has become increasingly common in recent military conflicts. The mechanisms by which non-impact blast exposure results in bTBI are incompletely understood. Current small animal bTBI models predominantly utilize compressed air-driven membrane rupture as their blast wave source, while large animal models use chemical explosives. The pressure-time signature of each blast mode is unique, making it difficult to evaluate the contributions of the different components of the blast wave to bTBI when using a single blast source. We utilized a multi-mode shock tube, the McMillan blast device, capable of utilizing compressed air- and compressed helium-driven membrane rupture, and the explosives oxyhydrogen and cyclotrimethylenetrinitramine (RDX, the primary component of C-4 plastic explosives) as the driving source. At similar maximal blast overpressures, the positive pressure phase of compressed air-driven blasts was longer, and the positive impulse was greater, than those observed for shockwaves produced by other driving sources. Helium-driven shockwaves more closely resembled RDX blasts, but by displacing air created a hypoxic environment within the shock tube. Pressure-time traces from oxyhydrogen-driven shockwaves were very similar those produced by RDX, although they resulted in elevated carbon monoxide levels due to combustion of the polyethylene bag used to contain the gases within the shock tube prior to detonation. Rats exposed to compressed air-driven blasts had more pronounced vascular damage than those exposed to oxyhydrogen-driven blasts of the same peak overpressure, indicating that differences in blast wave characteristics other than peak overpressure may influence the extent of bTBI. Use of this multi-mode shock tube in small animal models will enable comparison of the extent of brain injury with the pressure-time signature produced using each blast mode, facilitating evaluation of the blast wave components

  4. Multi-Mode transport modeling of the International Thermonuclear Experimental Reactor (ITER)

    SciTech Connect

    Bateman, G.; Kritz, A.H.; Kinsey, J.E.; Redd, A.J.

    1998-06-01

    Predictions are made for the performance of the International Thermonuclear Experimental Reactor (ITER) [R. Aymar, V. Chuyanov, M. Huguet, R. Parker, and Y. Shimomura, in {ital Proceedings of the Sixteenth International Atomic Energy Agency Fusion Energy Conference, Montr{acute e}al, Canada 1996} (International Atomic Energy Agency, Vienna, 1997), Paper IAEA-CN-64/01-1] design using the Multi-Mode model in the time-dependent one- and one-half-dimensional (1-1/2-D) BALDUR [C. E. Singer {ital et al.}, Comput. Phys. Commun. {bold 49}, 275 (1988)] transport code. This model predicts the temperature and density profiles observed in present-day tokamak experiments more closely on the average than other models currently available. Simulations using the Multi-Mode transport model, with its inherent gyro-Bohm scaling, indicate that ITER will ignite, even with edge temperatures as low as 0.25 keV (L-mode, or low-confinement mode, boundary conditions) or with volume averaged density as low as 0.775{times}10{sup 20}m{sup {minus}3} (just below the Greenwald density limit, when T{sub edge}=0.75keV). The ignition is found to be thermally stable, and the fusion power production is easily controlled by varying plasma density, impurity content, or edge temperatures. The nonequilibrium impurity radiation model used in these simulations predicts that a significant fraction of the fusion power is radiated when conditions are close to marginal ignition. {copyright} {ital 1998 American Institute of Physics.}

  5. A Multi-Mode Shock Tube for Investigation of Blast-Induced Traumatic Brain Injury

    PubMed Central

    Reneer, Dexter V.; Hisel, Richard D.; Hoffman, Joshua M.; Kryscio, Richard J.; Lusk, Braden T.

    2011-01-01

    Abstract Blast-induced mild traumatic brain injury (bTBI) has become increasingly common in recent military conflicts. The mechanisms by which non-impact blast exposure results in bTBI are incompletely understood. Current small animal bTBI models predominantly utilize compressed air-driven membrane rupture as their blast wave source, while large animal models use chemical explosives. The pressure-time signature of each blast mode is unique, making it difficult to evaluate the contributions of the different components of the blast wave to bTBI when using a single blast source. We utilized a multi-mode shock tube, the McMillan blast device, capable of utilizing compressed air- and compressed helium-driven membrane rupture, and the explosives oxyhydrogen and cyclotrimethylenetrinitramine (RDX, the primary component of C-4 plastic explosives) as the driving source. At similar maximal blast overpressures, the positive pressure phase of compressed air-driven blasts was longer, and the positive impulse was greater, than those observed for shockwaves produced by other driving sources. Helium-driven shockwaves more closely resembled RDX blasts, but by displacing air created a hypoxic environment within the shock tube. Pressure-time traces from oxyhydrogen-driven shockwaves were very similar those produced by RDX, although they resulted in elevated carbon monoxide levels due to combustion of the polyethylene bag used to contain the gases within the shock tube prior to detonation. Rats exposed to compressed air-driven blasts had more pronounced vascular damage than those exposed to oxyhydrogen-driven blasts of the same peak overpressure, indicating that differences in blast wave characteristics other than peak overpressure may influence the extent of bTBI. Use of this multi-mode shock tube in small animal models will enable comparison of the extent of brain injury with the pressure-time signature produced using each blast mode, facilitating evaluation of the blast wave

  6. Multi-Mode Electromagnetic Ultrasonic Lamb Wave Tomography Imaging for Variable-Depth Defects in Metal Plates.

    PubMed

    Huang, Songling; Zhang, Yu; Wang, Shen; Zhao, Wei

    2016-05-02

    This paper proposes a new cross-hole tomography imaging (CTI) method for variable-depth defects in metal plates based on multi-mode electromagnetic ultrasonic Lamb waves (LWs). The dispersion characteristics determine that different modes of LWs are sensitive to different thicknesses of metal plates. In this work, the sensitivities to thickness variation of A0- and S0-mode LWs are theoretically studied. The principles and procedures for the cooperation of A0- and S0-mode LW CTI are proposed. Moreover, the experimental LW imaging system on an aluminum plate with a variable-depth defect is set up, based on A0- and S0-mode EMAT (electromagnetic acoustic transducer) arrays. For comparison, the traditional single-mode LW CTI method is used in the same experimental platform. The imaging results show that the computed thickness distribution by the proposed multi-mode method more accurately reflects the actual thickness variation of the defect, while neither the S0 nor the A0 single-mode method was able to distinguish thickness variation in the defect region. Moreover, the quantification of the defect's thickness variation is more accurate with the multi-mode method. Therefore, theoretical and practical results prove that the variable-depth defect in metal plates can be successfully quantified and visualized by the proposed multi-mode electromagnetic ultrasonic LW CTI method.

  7. Multi-Mode Electromagnetic Ultrasonic Lamb Wave Tomography Imaging for Variable-Depth Defects in Metal Plates

    PubMed Central

    Huang, Songling; Zhang, Yu; Wang, Shen; Zhao, Wei

    2016-01-01

    This paper proposes a new cross-hole tomography imaging (CTI) method for variable-depth defects in metal plates based on multi-mode electromagnetic ultrasonic Lamb waves (LWs). The dispersion characteristics determine that different modes of LWs are sensitive to different thicknesses of metal plates. In this work, the sensitivities to thickness variation of A0- and S0-mode LWs are theoretically studied. The principles and procedures for the cooperation of A0- and S0-mode LW CTI are proposed. Moreover, the experimental LW imaging system on an aluminum plate with a variable-depth defect is set up, based on A0- and S0-mode EMAT (electromagnetic acoustic transducer) arrays. For comparison, the traditional single-mode LW CTI method is used in the same experimental platform. The imaging results show that the computed thickness distribution by the proposed multi-mode method more accurately reflects the actual thickness variation of the defect, while neither the S0 nor the A0 single-mode method was able to distinguish thickness variation in the defect region. Moreover, the quantification of the defect’s thickness variation is more accurate with the multi-mode method. Therefore, theoretical and practical results prove that the variable-depth defect in metal plates can be successfully quantified and visualized by the proposed multi-mode electromagnetic ultrasonic LW CTI method. PMID:27144571

  8. Self-imaging and high-beam-quality operation in multi-mode planar waveguide optical amplifiers.

    PubMed

    Baker, Howard; Lee, Jason; Hall, Denis

    2002-03-25

    Self-imaging in a multi-mode active waveguide is examined as a method to preserve beam quality when amplifying a fundamental gaussian beam. Misalignment tolerance, gain saturation and thermal lensing effects are evaluated for the use of self-imaging in high average power, diodepumped, planar waveguide lasers.

  9. Adhesive performance of a multi-mode adhesive system: 1-year in vitro study.

    PubMed

    Marchesi, Giulio; Frassetto, Andrea; Mazzoni, Annalisa; Apolonio, Fabianni; Diolosà, Marina; Cadenaro, Milena; Di Lenarda, Roberto; Pashley, David H; Tay, Franklin; Breschi, Lorenzo

    2014-05-01

    The aim of this study was to investigate the adhesive stability over time of a multi-mode one-step adhesive applied using different bonding techniques on human coronal dentine. The hypotheses tested were that microtensile bond strength (μTBS), interfacial nanoleakage expression and matrix metalloproteinases (MMPs) activation are not affected by the adhesive application mode (following the use of self-etch technique or with the etch-and-rinse technique on dry or wet dentine) or by ageing for 24h, 6 months and 1year in artificial saliva. Human molars were cut to expose middle/deep dentine and assigned to one of the following bonding systems (N=15): (1) Scotchbond Universal (3M ESPE) self-etch mode, (2) Scotchbond Universal etch-and-rinse technique on wet dentine, (3) Scotchbond Universal etch-and-rinse technique on dry dentine, and (4) Prime&Bond NT (Dentsply De Trey) etch-and-rinse technique on wet dentine (control). Specimens were processed for μTBS test in accordance with the non-trimming technique and stressed to failure after 24h, 6 months or 1 year. Additional specimens were processed and examined to assay interfacial nanoleakage and MMP expression. At baseline, no differences between groups were found. After 1 year of storage, Scotchbond Universal applied in the self-etch mode and Prime&Bond NT showed higher μTBS compared to the other groups. The lowest nanoleakage expression was found for Scotchbond Universal applied in the self-etch mode, both at baseline and after storage. MMPs activation was found after application of each tested adhesive. The results of this study support the use of the self-etch approach for bonding the tested multi-mode adhesive system to dentine due to improved stability over time. Improved bonding effectiveness of the tested universal adhesive system on dentine may be obtained if the adhesive is applied with the self-etch approach. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Novel optical fiber design for DTS measurement purposes

    NASA Astrophysics Data System (ADS)

    Siska, Petr; Hajek, Lukas; Vasinek, Vladimir; Koudelka, Petr; Latal, Jan

    2015-07-01

    This article is dealing with an optical fiber refractive index design optimized for utilization in DTS (Distributed Temperature Sensing) measurements. Presented optical fiber uses wavelength of 850 nm for communication purposes and 1060 nm for sensory operation. The aim of this work is to design an optical fiber with redistribution of the optical field at 850 nm similar to communication multi-mode optical fiber 50/125 μm and for wavelength of 1060 nm the redistribution of the optical field will be shifted closer to the core-cladding boundary to increase its sensitivity to temperature. Optical properties obtained from fiber design are compared with standard multi-mode optical fiber with graded refractive index to ensure that new optical fiber design has better sensing characteristics, but still keeps good enough communication properties at the same time.

  11. The Aerosol Coarse Mode Initiative

    NASA Astrophysics Data System (ADS)

    Arnott, W. P.; Adhikari, N.; Air, D.; Kassianov, E.; Barnard, J.

    2014-12-01

    Many areas of the world show an aerosol volume distribution with a significant coarse mode and sometimes a dominant coarse mode. The large coarse mode is usually due to dust, but sea salt aerosol can also play an important role. However, in many field campaigns, the coarse mode tends to be ignored, because it is difficult to measure. This lack of measurements leads directly to a concomitant "lack of analysis" of this mode. Because, coarse mode aerosols can have significant effects on radiative forcing, both in the shortwave and longwave spectrum, the coarse mode -- and these forcings -- should be accounted for in atmospheric models. Forcings based only on fine mode aerosols have the potential to be misleading. In this paper we describe examples of large coarse modes that occur in areas of large aerosol loading (Mexico City, Barnard et al., 2010) as well as small loadings (Sacramento, CA; Kassianov et al., 2012; and Reno, NV). We then demonstrate that: (1) the coarse mode can contribute significantly to radiative forcing, relative to the fine mode, and (2) neglecting the coarse mode may result in poor comparisons between measurements and models. Next we describe -- in general terms -- the limitations of instrumentation to measure the coarse mode. Finally, we suggest a new initiative aimed at examining coarse mode aerosol generation mechanisms; transport and deposition; chemical composition; visible and thermal IR refractive indices; morphology; microphysical behavior when deposited on snow and ice; and specific instrumentation needs. Barnard, J. C., J. D. Fast, G. Paredes-Miranda, W. P. Arnott, and A. Laskin, 2010: Technical Note: Evaluation of the WRF-Chem "Aerosol Chemical to Aerosol Optical Properties" Module using data from the MILAGRO campaign, Atmospheric Chemistry and Physics, 10, 7325-7340. Kassianov, E. I., M. S. Pekour, and J. C. Barnard, 2012: Aerosols in Central California: Unexpectedly large contribution of coarse mode to aerosol radiative forcing

  12. Coarse coal hydraulic transport

    SciTech Connect

    Petry, E.F.

    1982-10-01

    Discusses the development of coarse coal pipeline technology requiring a minimum of product size reduction. Initial concentration on continuous face haulage and later on mainline haulage areas led eventually to the system in operation at Loveridge mine in West Virginia. Key features of the hydraulic transport system (as shown in diagram) include the pump house, vertical hoisting, overland slurry lines, a preparation/ dewatering plant, a continuous miner, a coal crusher/injection vehicle, a flexible hose hauler, a rigid slurry line, a longwall injection station, and a slurry storage/reclaim system. Explains that the system was built primarily to serve a longwall face, but it also handles coal from 2 continuous miners on longwall development work.

  13. Comparison of fiber length analyzers

    Treesearch

    Don Guay; Nancy Ross Sutherland; Walter Rantanen; Nicole Malandri; Aimee Stephens; Kathleen Mattingly; Matt Schneider

    2005-01-01

    In recent years, several fiber new fiber length analyzers have been developed and brought to market. The new instruments provide faster measurements and the capability of both laboratory and on-line analysis. Do the various fiber analyzers provide the same length, coarseness, width, and fines measurements for a given fiber sample? This paper provides a comparison of...

  14. A Multi-Moded RF Delay Line Distribution System (MDLDS) for the Next Linear Collider

    SciTech Connect

    Nantista, Christopher D.

    2002-01-17

    The Delay Line Distribution System (DLDS) is an alternative to conventional pulse compression, which enhances the peak power of rf sources while matching the long pulse of those sources to the shorter filling time of accelerator structures. We present an implementation of this scheme that combines pairs of parallel delay lines of the system into single lines. The power of several sources is combined into a single waveguide delay line using a multi-mode launcher. The output mode of the launcher is determined by the phase coding of the input signals. The combined power is extracted from the delay line using mode-selective extractors, each of which extracts a single mode. Hence, the phase coding of the sources controls the output port of the combined power. The power is then fed to the local accelerator structures. We present a detailed design of such a system, including several implementation methods for the launchers, extractors, and ancillary high power rf components. The system is designed so that it can handle the 600 MW peak power required by the NLC design while maintaining high efficiency.

  15. Energy-efficient multi-mode compressed sensing system for implantable neural recordings.

    PubMed

    Suo, Yuanming; Zhang, Jie; Xiong, Tao; Chin, Peter S; Etienne-Cummings, Ralph; Tran, Trac D

    2014-10-01

    Widely utilized in the field of Neuroscience, implantable neural recording devices could capture neuron activities with an acquisition rate on the order of megabytes per second. In order to efficiently transmit neural signals through wireless channels, these devices require compression methods that reduce power consumption. Although recent Compressed Sensing (CS) approaches have successfully demonstrated their power, their full potential is yet to be explored. Built upon our previous on-chip CS implementation, we propose an energy efficient multi-mode CS framework that focuses on improving the off-chip components, including (i) a two-stage sensing strategy, (ii) a sparsifying dictionary directly using data, (iii) enhanced compression performance from Full Signal CS mode and Spike Restoration mode to Spike CS + Restoration mode and; (iv) extension of our framework to the Tetrode CS recovery using joint sparsity. This new framework achieves energy efficiency, implementation simplicity and system flexibility simultaneously. Extensive experiments are performed on simulation and real datasets. For our Spike CS + Restoration mode, we achieve a compression ratio of 6% with a reconstruction SNDR > 10 dB and a classification accuracy > 95% for synthetic datasets. For real datasets, we get a 10% compression ratio with  ∼  10 dB for Spike CS + Restoration mode.

  16. Does Sequence Matter in Multi-Mode Surveys: Results from an Experiment

    PubMed Central

    Wagner, James; Arrieta, Jennifer; Guyer, Heidi; Ofstedal, Mary Beth

    2014-01-01

    Interest in a multi-mode approach to surveys has grown substantially in recent years, in part due to increased costs of face-to-face interviewing and the emergence of the internet as a survey mode. Yet, there is little systematic evidence of the impact of a multimode approach on survey costs and errors. This paper reports the results of an experiment designed to evaluate whether a mixed-mode approach to a large screening survey would produce comparable response rates at a lower cost than a face-to-face screening effort. The experiment was carried out in the Health and Retirement Study (HRS), an ongoing panel study of Americans over age 50. In 2010, HRS conducted a household screening survey to recruit new sample members to supplement the existing sample. The experiment varied the sequence of modes with which the screening interview was delivered. One treatment offered mail first, followed by face-to-face interviewing; the other started with face-to-face and then mail. A control group was offered only face-to-face interviewing. Results suggest that the mixed mode options reduced costs without reducing response rates to the screening interview. There is some evidence, however, that the sequence of modes offered may impact the response rate for a follow-up in-depth interview PMID:24764767

  17. Lynx multi-mode SAR in support of NATO Unified Vision 2012 trial

    NASA Astrophysics Data System (ADS)

    Dunkel, R.; Verge, T.; Linnehan, R.; Doerry, A.

    2013-05-01

    In June 2012, General Atomics Aeronautical Systems, Inc. (GA-ASI) Reconnaissance Systems Group participated in the NATO Unified Vision 2012 (UV12) Joint ISR (JISR) Trial at Orland Main Air Station in Brekstad, Norway. GA-ASI supplied a modified King Air 200 as a Predator B/MQ-9 Reaper Remotely Piloted Aircraft (RPA) surrogate outfitted with a Lynx Block 30 Multi-mode Synthetic Aperture Radar/Ground Moving Target Indicator (SAR/GMTI), a FLIR Star SAFIRE 3800HD Electro-optical/Infrared (EO/IR) sensor, and a L-3 Tactical Common Data Link. This airborne platform was combined with GA-ASI's new System for Tactical Archival, Retrieval, and Exploitation (STARE) for full integration into the NATO ISR exploitation community. UV12 was an event sponsored by the NATO Joint Capability Group on Intelligence, Surveillance, and Reconnaissance (ISR) to focus on the interoperability of national ISR assets and improving JISR concept of operations. The Predator B RPA surrogate flew alongside multiple NATO ISR assets in nine missions that showcased the platform's all-weather ISR capabilities focusing on the Lynx SAR/GMTI and Maritime Wide Area Search (MWAS) modes. The inclusion of the STARE technology allowed GA-ASI's radar and Full Motion Video (FMV) data to be seamlessly processed and passed to joint networks where the data was fused with other NATO ISR products, resulting in a full battlefield reconnaissance picture.

  18. Development of multi-mode diabatic spin-orbit models at arbitrary order

    NASA Astrophysics Data System (ADS)

    Weike, Thomas; Eisfeld, Wolfgang

    2016-03-01

    The derivation of diabatic spin-orbit (SO) Hamiltonians is presented, which are expanded in terms of nuclear coordinates to arbitrary order including the treatment of multi-mode systems, having more than one mode of the same symmetry. The derivation is based on the microscopic Breit-Pauli SO operator and the consequent utilization of time reversal and spatial symmetry transformation properties of basis functions and coordinates. The method is demonstrated for a set of 2E and 2A1 states in C3 v ∗ (double group) symmetry, once for a 3D case of one a1 and one e mode and once for a 9D case of three a1 and three e coordinates. It is shown that the general structure of the diabatic SO Hamiltonian only depends on the basis states and is strictly imposed by time reversal symmetry. The resulting matrix can be expressed easily by a power series using six parametrized structure matrices as expansion coefficients multiplied by the associated monomials in terms of symmetrized coordinates. The explicit example presented here provides a full-dimensional diabatic SO model for methyl halide cations, which will be studied in the future.

  19. Characterisation of multi-mode propagation in silicon nitride slab waveguides

    NASA Astrophysics Data System (ADS)

    Jennings, B. D.; McCloskey, D.; Gough, J. J.; Hoang, T.; Abadía, N.; Zhong, C.; Karademir, E.; Bradley, A. L.; Donegan, J. F.

    2017-01-01

    A simple experimental method for determining the number of modes in planar dielectric multi-mode waveguides, and the effective index difference of these modes, is presented. Applying a thin, dye-doped polymer cladding, the fluorescence excited by multiple modes propagating in a silicon nitride slab waveguide is imaged to extract information. Interference between the modes produces a structured intensity profile along the waveguide which is constant in time. The spatial frequencies of this intensity profile are directly linked to the propagation constants of the underlying modes. Through a discrete Fourier transform, the modes’ effective index differences are found and compare well with analytically calculated values. Furthermore, the amplitudes in the Fourier transform are directly related to the power in each mode. Comparing the amplitudes of the Fourier components as a function of propagation distance, an estimate of the propagation losses of the individual modes relative to one another is made. The method discussed could be applied to analysing mode behaviour in integrated photonic devices, most notably in mode-division multiplexing.

  20. An inductorless multi-mode RF front end for GNSS receiver in 55 nm CMOS

    NASA Astrophysics Data System (ADS)

    Yanbin, Luo; Chengyan, Ma; Yebing, Gan; Min, Qian; Tianchun, Ye

    2015-10-01

    An inductorless multi-mode RF front end for a global navigation satellite system (GNSS) receiver is presented. Unlike the traditional topology of a low noise amplifier (LNA), the inductorless current-mode noise-canceling LNA is applied in this design. The high-impedance-input radio frequency amplifier (RFA) further amplifies the GNSS signals and changes the single-end signal path into fully differential. The passive mixer down-converts the signals to the intermediate frequency (IF) band and conveys the signals to the analogue blocks. The local oscillator (LO) buffer divides the output frequency of the voltage controlled oscillator (VCO) and generates 25%-duty-cycle quadrature square waves to drive the mixer. Our measurement results display that the implemented RF front end achieves good overall performance while consuming only 6.7 mA from 1.2 V supply. The input return loss is better than -26 dB and the ultra low noise figure of 1.43 dB leads to high sensitivity of the GNSS receiver. The input 1 dB compression point is -43 dBm at the high gain of 48 dB. The designed circuit is fabricated in 55 nm CMOS technology and the die area, which is much smaller than traditional circuit, is around 220 × 280 μm2.

  1. A multi-moded rf delay line distribution system for the next linear collider

    SciTech Connect

    Tantawi, S.G.; Bowden, G.; Farkas, Z.D.; Irwin, J.; Ko, K.; Kroll, N.; Lavine, T.; Li, Z.; Loewen, R.; Miller, R.; Nantista, C.; Ruth, R.D.; Rifkin, J.; Vlieks, A.E.; Wilson, P.B.; Adolphsen, C.; Wang, J.

    1999-07-01

    The Delay Line Distribution System (DLDS) (1) is an alternative to conventional pulse compression which enhances the peak power of an rf source while matching the long pulse of that source to the shorter filling time of the accelerator structure. We present a variation on that scheme that combines the parallel delay lines of the system into one single line. The power of several sources is combined into a single waveguide delay line using a multi-mode launcher. The output mode of the launcher is determined by the phase coding of the input signals. The combined power is extracted using several mode extractors, each of which extracts only one single mode. Hence, the phase coding of the sources controls the output port of the combined power. The power is then fed to the local accelerator structures. We present a detailed design of such a system, including several implementation methods for the launchers, extractors, and ancillary high power rf components. The system is designed so that it can handle the 600 MW peak power required by the NLC design, while maintaining high efficiency. {copyright} {ital 1999 American Institute of Physics.}

  2. Subsurface Optical Microscopy of Coarse Grain Spinels. Phase 1

    DTIC Science & Technology

    2013-12-01

    A 456 nm LED line bar illuminated in figure 15 and a Xenon fiber optic bar illuminator is shown for figure 16. The optical in situ or subsurface ... imaging of coarse grain spinels and AlONs is optically more complex than expected. An overhead view of the side illumination field is shown in figure 20

  3. Optical techniques: using coarse and detailed scans for the preventive acquisition of fingerprints with chromatic white-light sensors

    NASA Astrophysics Data System (ADS)

    Hildebrandt, Mario; Dittmann, Jana; Vielhauer, Claus; Leich, Marcus

    2011-11-01

    The preventive application of automated latent fingerprint acquisition devices can enhance the Homeland Defence, e.g. by improving the border security. Here, contact-less optical acquisition techniques for the capture of traces are subject to research; chromatic white light sensors allow for multi-mode operation using coarse or detailed scans. The presence of potential fingerprints could be detected using fast coarse scans. Those Regions-of- Interest can be acquired afterwards with high-resolution detailed scans to allow for a verification or identification of individuals. An acquisition and analysis of fingerprint traces on different objects that are imported or pass borders might be a great enhancement for security. Additionally, if suspicious objects require a further investigation, an initial securing of potential fingerprints could be very useful. In this paper we show current research results for the coarse detection of fingerprints to prepare the detailed acquisition from various surface materials that are relevant for preventive applications.

  4. FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): Ld-Clad-Pumped All-Fiber Tm3+-Doped Silica Fiber Laser

    NASA Astrophysics Data System (ADS)

    Zhang, Yun-Jun; Song, Shi-Fei; Tian, Yi; Wang, Yue-Zhu

    2009-08-01

    The CW 39.4 W all-fiber LD-clad-pumped Tm3+-doped fiber laser output is reported with a slope efficiency of 34% in respect to the pump power. The all-fiber laser is made up by progressively splicing the pigtail fiber, matched FBG fiber and Tm-doped fiber. The reflective FBG and Tm-doped fiber end fresnel reflection build up the laser resonance cavity. Due to the multi-mode FBG as the reflective mirror, the output laser spectrum is multi-peaks at high power output, whereas the total spectrum width is less than 2nm at nearly 1.94 μm.

  5. Learning effects on muscle modes and multi-mode postural synergies.

    PubMed

    Asaka, Tadayoshi; Wang, Yun; Fukushima, Junko; Latash, Mark L

    2008-01-01

    We used the framework of the uncontrolled manifold hypothesis to explore the effects of practice on the composition of muscle groups (M-modes) and multi-M-mode synergies stabilizing the location of the center of pressure (COP). In particular, we tested a hypothesis that practice could lead to a transition from co-contraction muscle activation patterns to reciprocal patterns. We also tested a hypothesis that new sets of M-modes would form stronger synergies stabilizing COP location. Subjects practiced load release tasks for five days while standing on a board with a narrow support surface (unstable board). Their M-modes and indices of multi-M-mode synergies were computed during standing without instability and during standing on an unstable board before practice, in the middle of practice, and at the end of practice. During standing without instability, subjects showed two consistent M-modes uniting dorsal and ventral muscles of the body respectively (reciprocal modes). While standing on an unstable board, prior to practice, subjects commonly showed M-modes uniting muscle pairs with opposing actions at major leg joints-co-contraction modes. Such sets of M-modes failed to stabilize the COP location in the anterior-posterior direction. Practice led to better task performance reflected in fewer incidences of lost balance. This was accompanied by a drop in the occurrence of co-contraction M-modes and the emergence of multi-mode synergies stabilizing the COP location. We conclude that the central nervous system uses flexible sets of elemental variables (modes) to ensure stable trajectories of important performance variables (such as COP location). Practice can lead to adjustments in both the composition of M-modes and M-mode co-variation patterns resulting in stronger synergies stabilizing COP location.

  6. MULTI-MODE ERROR FIELD CORRECTION ON THE DIII-D TOKAMAK

    SciTech Connect

    SCOVILLE, JT; LAHAYE, RJ

    2002-10-01

    OAK A271 MULTI-MODE ERROR FIELD CORRECTION ON THE DIII-D TOKAMAK. Error field optimization on DIII-D tokamak plasma discharges has routinely been done for the last ten years with the use of the external ''n = 1 coil'' or the ''C-coil''. The optimum level of correction coil current is determined by the ability to avoid the locked mode instability and access previously unstable parameter space at low densities. The locked mode typically has toroidal and poloidal mode numbers n = 1 and m = 2, respectively, and it is this component that initially determined the correction coil current and phase. Realization of the importance of nearby n = 1 mode components m = 1 and m = 3 has led to a revision of the error field correction algorithm. Viscous and toroidal mode coupling effects suggested the need for additional terms in the expression for the radial ''penetration'' field B{sub pen} that can induce a locked mode. To incorporate these effects, the low density locked mode threshold database was expanded. A database of discharges at various toroidal fields, plasma currents, and safety factors was supplement4ed with data from an experiment in which the fields of the n = 1 coil and C-coil were combined, allowing the poloidal mode spectrum of the error field to be varied. A multivariate regression analysis of this new low density locked mode database was done to determine the low density locked mode threshold scaling relationship n{sub e} {proportional_to} B{sub T}{sup -0.01} q{sub 95}{sup -0.79} B{sub pen} and the coefficients of the poloidal mode components in the expression for B{sub pen}. Improved plasma performance is achieved by optimizing B{sub pen} by varying the applied correction coil currents.

  7. Hybrid UWB and WiMAX radio-over-multi-mode fibre for in-building optical networks

    NASA Astrophysics Data System (ADS)

    Perez, J.; Llorente, R.

    2014-01-01

    In this paper the use of hybrid WiMedia-defined ultra-wideband (UWB) and IEEE 802.16d WiMAX radio-over-fibre is proposed and experimentally demonstrated for multi-mode based in-building optical networks with the advantage of great immunity to optical transmission impairments. In the proposed approach, spectral coexistence of both signals must be achieved with negligible mutual interference. The experimental study performed addressed an indoor configuration with 50 μm multi-mode fibres (MMF) and 850 nm vertical-cavity surface-emitting laser (VCSEL) transmitters. The results indicate that the impact of the wireless convergence in radio-over-multi-mode fibre (RoMMF) is significant for UWB transmissions, mainly due to MMF dispersion and electrooptical (EO) devices with limited bandwidth. On the other hand, WiMAX transmission is feasible for a 300 m MMF and 30 m wireless link in the presence of UWB, with -31 dBm WiMAX EVM.

  8. Bonding effectiveness of a new 'multi-mode' adhesive to enamel and dentine.

    PubMed

    Hanabusa, Masao; Mine, Atsushi; Kuboki, Takuo; Momoi, Yasuko; Van Ende, Annelies; Van Meerbeek, Bart; De Munck, Jan

    2012-06-01

    Self-etch adhesives are well adopted in general practice, obviously primarily thanks to their ease of use and fast application time. Nevertheless, phosphoric acid is still often recommended to beforehand etch enamel following a so-called 'selective' enamel-etch technique, this in particular when most cavity margins end in enamel. The purpose of this study was to test if a new one-step adhesive can be applied in a multi-mode manner, this following different, either 'full' or 'selective', self-etch and etch-and-rinse approaches. Specific research hypotheses tested were that prior phosphoric-acid etching did not affect the bonding effectiveness of the one-step adhesive to enamel and dentine, and that the bonding effectiveness to dentine was also not affected when the adhesive was applied either following a 'dry-bonding' or 'wet-bonding' etch-and-rinse technique. The micro-tensile bond strength (μTBS) of the one-step self-etch adhesive G-Bond Plus (GC, Tokyo, Japan; 1-SEA) was measured when it was bonded to bur-cut enamel following either a 'self-etch' or an 'etch-and-rinse' adhesive protocol, and to bur-cut dentine when applied following either a 'self-etch', a 'dry-bonding' or a 'wet-bonding' etch-and-rinse adhesive protocol. Bond-strength testing was corroborated by ultra-structural analysis of the interfacial interaction at enamel and dentine using transmission electron microscopy (TEM). Prior phosphoric-acid etching significantly increased the bonding effectiveness of the 1-SEA to enamel. A clearly enhanced micro-retentive surface was revealed by TEM. To dentine, no statistically significant difference in bonding effectiveness was recorded when the 1-SEA was either applied following a self-etch or both etch-and-rinse approaches. The 'dry-bonding' etch-and-rinse protocol was significantly more effective than its 'wet-bonding' version. TEM however revealed indications of low-quality hybridisation following both etch-and-rinse approaches, in particular in the form

  9. Development of Radar Control system for Multi-mode Active Phased Array Radar for atmospheric probing

    NASA Astrophysics Data System (ADS)

    Yasodha, Polisetti; Jayaraman, Achuthan; Thriveni, A.

    2016-07-01

    Modern multi-mode active phased array radars require highly efficient radar control system for hassle free real time radar operation. The requirement comes due to the distributed architecture of the active phased array radar, where each antenna element in the array is connected to a dedicated Transmit-Receive (TR) module. Controlling the TR modules, which are generally few hundreds in number, and functioning them in synchronisation, is a huge task during real time radar operation and should be handled with utmost care. Indian MST Radar, located at NARL, Gadanki, which is established during early 90's, as an outcome of the middle atmospheric program, is a remote sensing instrument for probing the atmosphere. This radar has a semi-active array, consisting of 1024 antenna elements, with limited beam steering, possible only along the principle planes. To overcome the limitations and difficulties, the radar is being augmented into fully active phased array, to accomplish beam agility and multi-mode operations. Each antenna element is excited with a dedicated 1 kW TR module, located in the field and enables to position the radar beam within 20° conical volume. A multi-channel receiver makes the radar to operate in various modes like Doppler Beam Swinging (DBS), Spaced Antenna (SA), Frequency Domain Interferometry (FDI) etc. Present work describes the real-time radar control (RC) system for the above described active phased array radar. The radar control system consists of a Spartan 6 FPGA based Timing and Control Signal Generator (TCSG), and a computer containing the software for controlling all the subsystems of the radar during real-time radar operation and also for calibrating the radar. The main function of the TCSG is to generate the control and timing waveforms required for various subsystems of the radar. Important components of the RC system software are (i) TR module configuring software which does programming, controlling and health parameter monitoring of the

  10. [Comparison of learning effects using high-fidelity and multi-mode simulation: an application of emergency care for a patient with cardiac arrest].

    PubMed

    Ryoo, Eon Na; Ha, Eun Ho; Cho, Jin Young

    2013-04-01

    Simulation-based learning has become a powerful method to improve the quality of care and help students meet the challenges of increasingly complex clinical practice settings. The purpose of this study was to identify the learning effects using high-fidelity SimMan and multi-mode simulation. Participants in this study were 38 students who were enrolled in an intensive course for a major in nursing at R college. Collected data were analyzed using Chi-square, t-test, and independent t-test with the SPSS 18.0 for Windows Program. There were no statistically significant differences in learning effects between high-fidelity SimMan and multi-mode simulation group. However, skills in clinical performance in the high-fidelity SimMan group were higher than in the multi-mode group (p=.014), communication in clinical performance in multi-mode simulation group was higher than in the high-fidelity SimMan group (p<.001). Multi-mode simulation with a standardized patient is an effective learning method in many ways compared to a high-fidelity simulator. These results suggest that multi-mode simulation be offered to students in nursing colleges which cannot afford to purchase a high-fidelity simulator, or offered as an alternative.

  11. INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Multi-mode Spiral Wave in a Coupled Oscillatory Medium

    NASA Astrophysics Data System (ADS)

    Wang, Qun; Gao, Qing-Yu; Lü, Hua-Ping; Zheng, Zhi-Gang

    2010-05-01

    Multi-mode spiral wave and its breakup in 1-d and 2-d coupled oscillatory media is studied here by theoretic analysis and numerical simulations. The analysis in 1-d system shows that the dispersion relation curve could be non-monotonic depending on the coupling strength. It may also lead to the coexistence of different wave numbers within one system. Direct numerical observations in 1-d and 2-d systems conform to the prediction of dispersion relation analysis. Our findings indicate that the wave grouping can also be observed in oscillatory media without tip meandering and waves with negative group velocity can occur without inhomogeneity.

  12. Simultaneously coherent excitation of multi-modes THz radiation from dielectric loaded waveguide by pre-bunched electron beam

    NASA Astrophysics Data System (ADS)

    Li, Biaobin; Lu, Yalin; He, Zhigang; Li, Weiwei; Jia, Qika; Wang, Lin

    2017-02-01

    The cylindrical dielectric loaded waveguide (DLW) supports a discrete set of modes, which can be excited by electron beam passing through the structure, and the high-order modes can be the harmonics of the fundamental one by properly choosing the parameters of the DLW. By using a train of electron bunches, repeated at the fundamental frequency of the DLW, as the driving source, coherent and simultaneous excitation of multi-modes can be expected. With this proposed scheme, multi-color narrow-band THz radiation with high pulse power and high frequency can be obtained simultaneously.

  13. A multi-mode operation control strategy for flexible microgrid based on sliding-mode direct voltage and hierarchical controls.

    PubMed

    Zhang, Qinjin; Liu, Yancheng; Zhao, Youtao; Wang, Ning

    2016-03-01

    Multi-mode operation and transient stability are two problems that significantly affect flexible microgrid (MG). This paper proposes a multi-mode operation control strategy for flexible MG based on a three-layer hierarchical structure. The proposed structure is composed of autonomous, cooperative, and scheduling controllers. Autonomous controller is utilized to control the performance of the single micro-source inverter. An adaptive sliding-mode direct voltage loop and an improved droop power loop based on virtual negative impedance are presented respectively to enhance the system disturbance-rejection performance and the power sharing accuracy. Cooperative controller, which is composed of secondary voltage/frequency control and phase synchronization control, is designed to eliminate the voltage/frequency deviations produced by the autonomous controller and prepare for grid connection. Scheduling controller manages the power flow between the MG and the grid. The MG with the improved hierarchical control scheme can achieve seamless transitions from islanded to grid-connected mode and have a good transient performance. In addition the presented work can also optimize the power quality issues and improve the load power sharing accuracy between parallel VSIs. Finally, the transient performance and effectiveness of the proposed control scheme are evaluated by theoretical analysis and simulation results.

  14. Small-signal analysis of ultra-high-speed 30 GHz VCSELs using an advanced multi-mode approach

    NASA Astrophysics Data System (ADS)

    Hamad, Wissam; Bou Sanayeh, Marwan; Hamad, Hassan; Hamad, Mustapha; Georges, Semaan; Hofmann, Werner

    2017-05-01

    Vertical-cavity surface-emitting lasers (VCSELs) have emerged as a pioneering solution for many high-speed data communication challenges. Therefore, higher bandwidth optical interconnects with data rates in the range of 100 Gbit/s require directly modulated VCSELs with ultimate speed ratings. The small-signal modulation response of a VCSEL can be isolated from the entire system, thus providing accurate information on the intrinsic laser dynamics. Until now, it is assumed that the dynamic behavior of oxide-confined multi-mode VCSELs can be fully modeled using the single-mode rate equations developed for edge-emitters, even though the deviation between the single-mode based model and the measured data is substantially large. Using an advanced theoretical approach, rate equations for multi-mode VCSELs were developed and the small-signal modulation response of ultra-high speed devices with split carrier reservoirs corresponding with the resonating modes were analyzed. Based on this theoretical work, and including gain compression in the model, the analyzed VCSELs showed modulation bandwidth around and exceeding 30 GHz. The common set of figures of merit is extended consistently to explain dynamic properties caused by the coupling of the different reservoirs. Furthermore, beside damping and relaxation oscillation frequency, the advanced model, with gain compression included, can reveal information on the photon lifetime and highlights high-speed effects such as reduced damping in VCSELs due to a negative gain compression factor.

  15. Sparse Representation Based Frequency Detection and Uncertainty Reduction in Blade Tip Timing Measurement for Multi-Mode Blade Vibration Monitoring

    PubMed Central

    Pan, Minghao; Yang, Yongmin; Guan, Fengjiao; Hu, Haifeng; Xu, Hailong

    2017-01-01

    The accurate monitoring of blade vibration under operating conditions is essential in turbo-machinery testing. Blade tip timing (BTT) is a promising non-contact technique for the measurement of blade vibrations. However, the BTT sampling data are inherently under-sampled and contaminated with several measurement uncertainties. How to recover frequency spectra of blade vibrations though processing these under-sampled biased signals is a bottleneck problem. A novel method of BTT signal processing for alleviating measurement uncertainties in recovery of multi-mode blade vibration frequency spectrum is proposed in this paper. The method can be divided into four phases. First, a single measurement vector model is built by exploiting that the blade vibration signals are sparse in frequency spectra. Secondly, the uniqueness of the nonnegative sparse solution is studied to achieve the vibration frequency spectrum. Thirdly, typical sources of BTT measurement uncertainties are quantitatively analyzed. Finally, an improved vibration frequency spectra recovery method is proposed to get a guaranteed level of sparse solution when measurement results are biased. Simulations and experiments are performed to prove the feasibility of the proposed method. The most outstanding advantage is that this method can prevent the recovered multi-mode vibration spectra from being affected by BTT measurement uncertainties without increasing the probe number. PMID:28758952

  16. Fiber optical ranging sensor for proximity fuse

    NASA Astrophysics Data System (ADS)

    Du, Fang; Chi, Zeying; You, Mingjun; Chen, Wenjian

    1996-09-01

    A fiber optical ranging sensor used in laser proximity fuze is described in this paper. In the fuze, pulse laser diode (LD) is used as light source and trigger signal is generated by comparing the reflected light pulses with the reference pulses by a correlator after they were converted into electric signals by PIN photodiodes. Multi-mode fibers and integrated optical devices are used in the system so that the structure can be more compact. Optical fiber delay line is used to offer precise delay time for reference channel.

  17. Optical fibers for high-resolution in vivo microendoscopic fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Oh, Gyungseok; Chung, Euiheon; Yun, Seok H.

    2013-12-01

    Optical fiber-based high-resolution fluorescence imaging techniques have promising applications in clinical practice and preclinical research using animals. Here we review the instrumentation and applications of microendoscopy based on various types of optical fibers. Single-mode fibers and double-clad fibers have been widely used for delivering light from light sources to tissues and collecting light from tissues to photodetectors. Coherent fiber bundles, cylindrical graded-index lenses, and multi-mode fibers have been employed in both beam-scanning and non-scanning microscopy. With continuing advances of optical fiber technologies, further innovations in optical microendoscopy are expected.

  18. A generalized network flow model for the multi-mode resource-constrained project scheduling problem with discounted cash flows

    NASA Astrophysics Data System (ADS)

    Chen, Miawjane; Yan, Shangyao; Wang, Sin-Siang; Liu, Chiu-Lan

    2015-02-01

    An effective project schedule is essential for enterprises to increase their efficiency of project execution, to maximize profit, and to minimize wastage of resources. Heuristic algorithms have been developed to efficiently solve the complicated multi-mode resource-constrained project scheduling problem with discounted cash flows (MRCPSPDCF) that characterize real problems. However, the solutions obtained in past studies have been approximate and are difficult to evaluate in terms of optimality. In this study, a generalized network flow model, embedded in a time-precedence network, is proposed to formulate the MRCPSPDCF with the payment at activity completion times. Mathematically, the model is formulated as an integer network flow problem with side constraints, which can be efficiently solved for optimality, using existing mathematical programming software. To evaluate the model performance, numerical tests are performed. The test results indicate that the model could be a useful planning tool for project scheduling in the real world.

  19. Simultaneous PIV/PLIF measurements of Richtmyer-Meshkov Instabilities from single- and multi-mode perturbed interfaces

    NASA Astrophysics Data System (ADS)

    Mejia-Alvarez, Ricardo; Wilson, Brandon; Prestridge, Kathy; Extreme Fluids Team

    2013-11-01

    To support validation of RANS and LES codes for single-interface Richtmyer-Meshkov mixing, the Extreme Fluids Team at Los Alamos National Laboratory commissioned a Vertical Shock Tube. This facility has the capability of generating statistically stationary single- and multi-mode spatial perturbations on the fluid interface prior to shock-interface interaction. The present study focuses on comparing the evolution of shock-driven mixing under two different spatial perturbation conditions after interacting with a M = 1.2 shock wave. High resolution simultaneous PIV and PLIF are used for capturing 2D instantaneous realizations of velocity and density at different stages of the evolving interface. Multiple realizations of the flow at each one of these evolution stages are obtained to characterize the flow statistically. Also, a modal analysis via Singular Value Decomposition is performed on the density and velocity fields to elucidate the role of initial flow scales content on the transition to turbulent mixing.

  20. Three-coherent-output narrow-linewidth and tunable single frequency 1x2 multi-mode-interferometer laser diode.

    PubMed

    Yang, Hua; Yang, Mingqi; Morrissey, Padraic E; Lu, Dan; Pan, Bi Wei; Zhao, Lingjuan; Corbett, Brian; Peters, Frank H

    2016-03-21

    A 1x2 multi-mode-interferometer (MMI) laser diode was successfully designed and fabricated, which demonstrated three coherent outputs of tunable single frequency emission with more than 30dB side mode suppression ratio (SMSR), a tuning range of 25nm in C and L band, as well as 750 kHz linewidth. This 1x2 MMI laser could be expanded to more advanced configurations such as 1xN or MxN (M≥1, N>2) MMI lasers to achieve a multiple coherent output source. In addition, these lasers do not require material regrowth and high resolution gratings which can significantly increase the yield and reduce the cost.

  1. Radially anisotropic 3-D shear wave structure of the Australian lithosphere and asthenosphere from multi-mode surface waves

    NASA Astrophysics Data System (ADS)

    Yoshizawa, K.

    2014-10-01

    A new radially anisotropic shear wave speed model for the Australasian region is constructed from multi-mode phase dispersion of Love and Rayleigh waves. An automated waveform fitting technique based on a global optimization with the Neighbourhood Algorithm allows the exploitation of large numbers of three-component broad-band seismograms to extract path-specific dispersion curves covering the entire continent. A 3-D shear wave model is constructed including radial anisotropy from a set of multi-mode phase speed maps for both Love and Rayleigh waves. These maps are derived from an iterative inversion scheme incorporating the effects of ray-path bending due to lateral heterogeneity, as well as the finite frequency of the surface waves for each mode. The new S wave speed model exhibits major tectonic features of this region that are in good agreement with earlier shear wave models derived primarily from Rayleigh waves. The lateral variations of depth and thickness of the lithosphere-asthenosphere transition (LAT) are estimated from the isotropic (Voigt average) S wave speed model and its vertical gradient, which reveals correlations between the lateral variations of the LAT and radial anisotropy. The thickness of the LAT is very large beneath the Archean cratons in western Australia, whereas that in south Australia is thinner. The radial anisotropy model shows faster SH wave speed than SV beneath eastern Australia and the Coral Sea at the lithospheric depth. The faster SH anomaly in the lithosphere is also seen in the suture zone between the three cratonic blocks of Australia. One of the most conspicuous features of fast SH anisotropy is found in the asthenosphere beneath the central Australia, suggesting anisotropy induced by shear flow in the asthenosphere beneath the fast drifting Australian continent.

  2. Development of the multi-mode horn-lens configuration for the LSPE-SWIPE B-mode experiment

    NASA Astrophysics Data System (ADS)

    Legg, Stephen; Lamagna, Luca; Coppi, Gabriele; de Bernardis, Paolo; Giuliani, Grazia; Gualtieri, Riccardo; Marchetti, Tommaso; Masi, Silvia; Pisano, Giampaolo; Maffei, Bruno

    2016-07-01

    The Large Scale Polarisation Explorer (LSPE) is a balloon-borne experiment aiming to measure the B-mode component of the CMB polarisation at large angular scales. Onboard LSPE, the Short Wavelength Instrument for the Polarisation Explorer (SWIPE) is a bolometric polarimeter observing in three bands centred at 140, 220 and 240 GHz. The telescope is a single large-diameter plano-convex lens with a cold aperture stop. A small number of multi-mode feed horns feeding bolometric detectors are used within the focal plane, achieving a sensitivity equivalent to that of 100's of single-mode horns. Simulations have been performed to predict the multi-mode optical response of the horn-lens configuration for centre and off-axis pixels pertaining to each frequency band. The horn has been simulated to a high accuracy using the Method of Moments. Using the horn simulation result as a source, the optical response of the lens has been examined using the more approximate simulation technique; Ray-Launching Geometrical Optics (RL-GO). Solution accuracy and simulation time depend heavily on the choice of RL-GO simulation parameters including: mesh size; the number of launched rays; and how densely the horn source beam is sampled. Individual convergence studies have been performed for each of these parameters and a final model has been obtained as a compromise between simulation time and accuracy. The instrumental polarisation of the lens is predicted to be at the -50 dB level. Finally, the optimal location of where to place the telescope focus in relation to the horn to maximise on-axis gain has been investigated. Several techniques agreed that the `phase centre' is around 20 mm behind the horn aperture at 140 GHz, increasing to 30 mm at 220 and 240 GHz. Taking into account beam truncation effects caused by the finite size of the telescope was found to reduce the overall variation in on-axis gain.

  3. Continuous coarse ash depressurization system

    DOEpatents

    Liu, Guohai; Peng, Wan Wang; Vimalchand, Pannalal

    2012-11-13

    A system for depressurizing and cooling a high pressure, high temperature dense phase solids stream having coarse solid particles with entrained gas therein. In one aspect, the system has an apparatus for at least partially depressurizing and cooling the high pressure, high temperature dense phase solids stream having gas entrained therein and a pressure letdown device for further depressurization and separating cooled coarse solid particles from a portion of the entrained gas, resulting in a lower temperature, lower pressure outlet of solid particles for downstream processing or discharge to a storage silo for future use and/or disposal. There are no moving parts in the flow path of the solids stream in the system.

  4. Asymmetrically infiltrated twin core photonic crystal fiber for dual-parameter sensing

    NASA Astrophysics Data System (ADS)

    Liu, Shuhui; Wang, Zhe; Hou, Maoxiang; Tian, Jie; Xia, Jujiang

    2016-08-01

    We demonstrate a fiber-optic dual parameter sensor based on a water filled Mach-Zehnder interferometer. Such a sensor is fabricated by asymmetrically infiltrating a twin core photonic crystal fiber with water, and splicing it between single mode fibers. Two sets of interference fringes which result from multi-mode interference are obtained by such a structure. By measuring the wavelength shift of the small fringe and the big envelop of the spectrum, strain and temperature can be determined simultaneously.

  5. A multi-core fiber based interferometer for high temperature sensing

    NASA Astrophysics Data System (ADS)

    Zhou, Song; Huang, Bo; Shu, Xuewen

    2017-04-01

    In this paper, we have verified and implemented a Mach–Zehnder interferometer based on seven-core fiber for high temperature sensing application. This proposed structure is based on a multi-mode-multi-core-multi-mode fiber structure sandwiched by a single mode fiber. Between the single-mode and multi-core fiber, a 3 mm long multi-mode fiber is formed for lead-in and lead-out light. The basic operation principle of this device is the use of multi-core modes, single-mode and multi-mode interference coupling is also utilized. Experimental results indicate that this interferometer sensor is capable of accurate measurements of temperatures up to 800 °C, and the temperature sensitivity of the proposed sensor is as high as 170.2 pm/°C, which is much higher than the current existing MZI based temperature sensors (109 pm/°C). This type of sensor is promising for practical high temperature applications due to its advantages including high sensitivity, simple fabrication process, low cost and compactness.

  6. How coarse is too coarse for salmon spawning substrates?

    NASA Astrophysics Data System (ADS)

    Wooster, J. K.; Riebe, C. S.; Ligon, F. K.; Overstreet, B. T.

    2009-12-01

    Populations of Pacific salmon species have declined sharply in many rivers of the western US. Reversing these declines is a top priority and expense of many river restoration projects. To help restore salmon populations, managers often inject gravel into rivers, to supplement spawning habitat that has been depleted by gravel mining and the effects of dams—which block sediment and thus impair habitat downstream by coarsening the bed where salmon historically spawned. However, there is little quantitative understanding nor a methodology for determining when a river bed has become too coarse for salmon spawning. Hence there is little scientific basis for selecting sites that would optimize the restoration benefits of gravel injection (e.g., sites where flow velocities are suitable but bed materials are too coarse for spawning). To develop a quantitative understanding of what makes river beds too coarse for salmon spawning, we studied redds and spawning use in a series of California and Washington rivers where salmon spawning ability appears to be affected by coarse bed material. Our working hypothesis is that for a given flow condition, there is a maximum “threshold” particle size that a salmon of a given size is able to excavate and/or move as she builds her redd. A second, related hypothesis is that spawning use should decrease and eventually become impossible with increasing percent coverage by immovable particles. To test these hypotheses, we quantified the sizes and spatial distributions of immovably coarse particles in a series of salmon redds in each river during the peak of spawning. We also quantified spawning use and how it relates to percent coverage by immovable particles. Results from our studies of fall-run chinook salmon (Oncorhynchus tshawytsha) in the Feather River suggest that immovable particle size varies as a function of flow velocity over the redd, implying that faster water helps fish move bigger particles. Our Feather River study also

  7. Coarse Layering at 'Home Plate'

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This image shows coarse-grained layers from around the edge of a low plateau called 'Home Plate' inside Mars' Gusev Crater. One possible origin is material falling to the ground after being thrown aloft by an explosion such as a volcanic eruption or meteorite impact.

    The panoramic camera (Pancam) on NASA's Mars Exploration Rover Spirit acquired the exposures for this image on Spirit's 749th Martian day (Feb. 10, 2006). This view is an approximately true-color rendering mathematically generated from separate images taken through all of the left Pancam's 432-nanometer to 753-nanometer filters.

  8. Micro-controller based air pressure monitoring instrumentation system using optical fibers as sensor

    NASA Astrophysics Data System (ADS)

    Hazarika, D.; Pegu, D. S.

    2013-03-01

    This paper describes a micro-controller based instrumentation system to monitor air pressure using optical fiber sensors. The principle of macrobending is used to develop the sensor system. The instrumentation system consists of a laser source, a beam splitter, two multi mode optical fibers, two Light Dependent Resistance (LDR) based timer circuits and a AT89S8252 micro-controller. The beam splitter is used to divide the laser beam into two parts and then these two beams are launched into two multi mode fibers. One of the multi mode fibers is used as the sensor fiber and the other one is used as the reference fiber. The use of the reference fiber is to eliminate the environmental effects while measuring the air pressure magnitude. The laser beams from the sensor and reference fibers are applied to two identical LDR based timer circuits. The LDR based timer circuits are interfaced to a micro-controller through its counter pins. The micro-controller samples the frequencies of the timer circuits using its counter-0 and counter-1 and the counter values are then processed to provide the measure of air pressure magnitude.

  9. Characterization of coarse particulate matter in school gyms

    SciTech Connect

    Branis, Martin; Safranek, Jiri

    2011-05-15

    We investigated the mass concentration, mineral composition and morphology of particles resuspended by children during scheduled physical education in urban, suburban and rural elementary school gyms in Prague (Czech Republic). Cascade impactors were deployed to sample the particulate matter. Two fractions of coarse particulate matter (PM{sub 10-2.5} and PM{sub 2.5-1.0}) were characterized by gravimetry, energy dispersive X-ray spectrometry and scanning electron microscopy. Two indicators of human activity, the number of exercising children and the number of physical education hours, were also recorded. Lower mass concentrations of coarse particulate matter were recorded outdoors (average PM{sub 10-2.5} 4.1-7.4 {mu}g m{sup -3} and PM{sub 2.5-1.0} 2.0-3.3 {mu}g m{sup -3}) than indoors (average PM{sub 10-2.5} 13.6-26.7 {mu}g m{sup -3} and PM{sub 2.5-1.0} 3.7-7.4 {mu}g m{sup -3}). The indoor concentrations of coarse aerosol were elevated during days with scheduled physical education with an average indoor-outdoor (I/O) ratio of 2.5-16.3 for the PM{sub 10-2.5} and 1.4-4.8 for the PM{sub 2.5-1.0} values. Under extreme conditions, the I/O ratios reached 180 (PM{sub 10-2.5}) and 19.1 (PM{sub 2.5-1.0}). The multiple regression analysis based on the number of students and outdoor coarse PM as independent variables showed that the main predictor of the indoor coarse PM concentrations is the number of students in the gym. The effect of outdoor coarse PM was weak and inconsistent. The regression models for the three schools explained 60-70% of the particular dataset variability. X-ray spectrometry revealed 6 main groups of minerals contributing to resuspended indoor dust. The most abundant particles were those of crustal origin composed of Si, Al, O and Ca. Scanning electron microscopy showed that, in addition to numerous inorganic particles, various types of fibers and particularly skin scales make up the main part of the resuspended dust in the gyms. In conclusion, school

  10. Characterization of coarse particulate matter in school gyms.

    PubMed

    Braniš, Martin; Šafránek, Jiří

    2011-05-01

    We investigated the mass concentration, mineral composition and morphology of particles resuspended by children during scheduled physical education in urban, suburban and rural elementary school gyms in Prague (Czech Republic). Cascade impactors were deployed to sample the particulate matter. Two fractions of coarse particulate matter (PM(10-2.5) and PM(2.5-1.0)) were characterized by gravimetry, energy dispersive X-ray spectrometry and scanning electron microscopy. Two indicators of human activity, the number of exercising children and the number of physical education hours, were also recorded. Lower mass concentrations of coarse particulate matter were recorded outdoors (average PM(10-2.5) 4.1-7.4 μg m(-3) and PM(2.5-1.0) 2.0-3.3 μg m(-3)) than indoors (average PM(10-2.5) 13.6-26.7 μg m(-3) and PM(2.5-1.0) 3.7-7.4 μg m(-3)). The indoor concentrations of coarse aerosol were elevated during days with scheduled physical education with an average indoor-outdoor (I/O) ratio of 2.5-16.3 for the PM(10-2.5) and 1.4-4.8 for the PM(2.5-1.0) values. Under extreme conditions, the I/O ratios reached 180 (PM(10-2.5)) and 19.1 (PM(2.5-1.0)). The multiple regression analysis based on the number of students and outdoor coarse PM as independent variables showed that the main predictor of the indoor coarse PM concentrations is the number of students in the gym. The effect of outdoor coarse PM was weak and inconsistent. The regression models for the three schools explained 60-70% of the particular dataset variability. X-ray spectrometry revealed 6 main groups of minerals contributing to resuspended indoor dust. The most abundant particles were those of crustal origin composed of Si, Al, O and Ca. Scanning electron microscopy showed that, in addition to numerous inorganic particles, various types of fibers and particularly skin scales make up the main part of the resuspended dust in the gyms. In conclusion, school gyms were found to be indoor microenvironments with high

  11. The power of coarse graining in biomolecular simulations

    PubMed Central

    Ingólfsson, Helgi I; Lopez, Cesar A; Uusitalo, Jaakko J; de Jong, Djurre H; Gopal, Srinivasa M; Periole, Xavier; Marrink, Siewert J

    2014-01-01

    Computational modeling of biological systems is challenging because of the multitude of spatial and temporal scales involved. Replacing atomistic detail with lower resolution, coarse grained (CG), beads has opened the way to simulate large-scale biomolecular processes on time scales inaccessible to all-atom models. We provide an overview of some of the more popular CG models used in biomolecular applications to date, focusing on models that retain chemical specificity. A few state-of-the-art examples of protein folding, membrane protein gating and self-assembly, DNA hybridization, and modeling of carbohydrate fibers are used to illustrate the power and diversity of current CG modeling. PMID:25309628

  12. Multi-Mode Estimation for Small Fixed Wing Unmanned Aerial Vehicle Localization Based on a Linear Matrix Inequality Approach.

    PubMed

    Elzoghby, Mostafa; Li, Fu; Arafa, Ibrahim I; Arif, Usman

    2017-04-18

    Information fusion from multiple sensors ensures the accuracy and robustness of a navigation system, especially in the absence of global positioning system (GPS) data which gets degraded in many cases. A way to deal with multi-mode estimation for a small fixed wing unmanned aerial vehicle (UAV) localization framework is proposed, which depends on utilizing a Luenberger observer-based linear matrix inequality (LMI) approach. The proposed estimation technique relies on the interaction between multiple measurement modes and a continuous observer. The state estimation is performed in a switching environment between multiple active sensors to exploit the available information as much as possible, especially in GPS-denied environments. Luenberger observer-based projection is implemented as a continuous observer to optimize the estimation performance. The observer gain might be chosen by solving a Lyapunov equation by means of a LMI algorithm. Convergence is achieved by utilizing the linear matrix inequality (LMI), based on Lyapunov stability which keeps the dynamic estimation error bounded by selecting the observer gain matrix (L). Simulation results are presented for a small UAV fixed wing localization problem. The results obtained using the proposed approach are compared with a single mode Extended Kalman Filter (EKF). Simulation results are presented to demonstrate the viability of the proposed strategy.

  13. A reconfigurable multi-mode multi-band transmitter with integrated frequency synthesizer for short-range wireless communication

    NASA Astrophysics Data System (ADS)

    Nan, Qi; Fan, Chen; Lingwei, Zhang; Xiaoman, Wang; Baoyong, Chi

    2013-09-01

    A reconfigurable multi-mode direct-conversion transmitter (TX) with integrated frequency synthesizer (FS) is presented. The TX as well as the FS is designed with a flexible architecture and frequency plan, which helps to support all the 433/868/915 MHz ISM band signals, with the reconfigurable bandwidth from 250 kHz to 2 MHz. In order to save power and chip area, only one 1.8 GHz VCO is adopted to cover the whole frequency range. All the operation modes can be regulated in real time by configuring the integrated register-bank through an SPI interface. Implemented in 180 nm CMOS, the FS achieves a frequency coverage of 320-460 MHz and 620-920 MHz. The lowest phase noise can be -107 dBc/Hz at a 100 kHz offset and -126 dBc/Hz at a 1 MHz offset. The transmitter features a + 10.2 dBm peak output power with a +9.5 dBm 1-dB-compression point and 250 kHz/500 kHz/1 MHz/2 MHz reconfigurable signal bandwidth.

  14. Rogue waves for a coupled nonlinear Schrödinger system in a multi-mode fibre

    NASA Astrophysics Data System (ADS)

    Li, Hui-Min; Tian, Bo; Wang, Deng-Shan; Sun, Wen-Rong; Xie, Xi-Yang; Liu, Lei

    2016-10-01

    In this paper, we investigate the rogue waves for an integrable coupled nonlinear Schrödinger (CNLS) system with the self-phase modulation, cross-phase modulation and four-wave mixing term, which can describe the propagation of optical waves in a multi-mode fibre. We construct a generalized Darboux transformation (GDT) for the CNLS system and find a gauge transformation which converts the Lax pair into the constant-coefficient differential equations. Solving those equations, we can obtain the vector solutions of the Lax pair. Using the GDT, we derive an iterative formula for the nth-order rogue-wave solutions for the CNLS system. We derive the first- and second-order rogue-wave solutions for the CNLS system and analyse the profiles for the rogue waves with respect to the self-phase modulation term a, cross-phase modulation term c and four-wave mixing term b, respectively. The rogue waves become thinner with the increase in the value for the real part of b and that the effect of a or c on the rogue waves is the same as the one of the real part of b.

  15. Model predictive control of an air suspension system with damping multi-mode switching damper based on hybrid model

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoqiang; Yuan, Chaochun; Cai, Yingfeng; Wang, Shaohua; Chen, Long

    2017-09-01

    This paper presents the hybrid modeling and the model predictive control of an air suspension system with damping multi-mode switching damper. Unlike traditional damper with continuously adjustable damping, in this study, a new damper with four discrete damping modes is applied to vehicle semi-active air suspension. The new damper can achieve different damping modes by just controlling the on-off statuses of two solenoid valves, which makes its damping adjustment more efficient and more reliable. However, since the damping mode switching induces different modes of operation, the air suspension system with the new damper poses challenging hybrid control problem. To model both the continuous/discrete dynamics and the switching between different damping modes, the framework of mixed logical dynamical (MLD) systems is used to establish the system hybrid model. Based on the resulting hybrid dynamical model, the system control problem is recast as a model predictive control (MPC) problem, which allows us to optimize the switching sequences of the damping modes by taking into account the suspension performance requirements. Numerical simulations results demonstrate the efficacy of the proposed control method finally.

  16. M4ARC: multi-model multi-mode adaptive resonant control for dynamically loaded flexible beam structures

    NASA Astrophysics Data System (ADS)

    Tjahyadi, H.; He, F.; Sammut, K.

    2008-08-01

    A hybrid multi-model-multi-mode adaptive resonant control (M4ARC) approach is proposed for dynamically loaded flexible beam structures to provide superior vibration damping performance as compared to its fixed-model and adaptive counterparts. The proposed approach uses a configurable controller, the parameters of which are updated using a fast and accurate on-line frequency identification method for N modes of interest. This method incorporates a simple supervision scheme that selects between the output of an N-mode filter bank (representing the multiple-fixed-model set) and the output of an estimator bank (representing the accurate model of the plant). The estimator bank comprises a multi-rate set of parallel N second-order recursive-least-squares estimators to achieve rapid parameter convergence. While the estimators are still in transition, the supervisor provides the configurable controller with an intermediate set of frequencies that correspond to the closest fixed model. Once the estimators converge, the supervisor selects the estimated frequency set to provide the configurable controller with an accurate representation of the current plant. This supervisor scheme significantly reduces the computational complexity as compared with existing counterparts. Experiments reveal that the proposed M4ARC approach offers the best compromise in terms of adapting to sudden and highly variable loading condition changes (within a bounded domain) while, at the same time, achieving fast transient performance.

  17. Semi-active damping with negative stiffness for multi-mode cable vibration mitigation: approximate collocated control solution

    NASA Astrophysics Data System (ADS)

    Weber, F.; Distl, H.

    2015-11-01

    This paper derives an approximate collocated control solution for the mitigation of multi-mode cable vibration by semi-active damping with negative stiffness based on the control force characteristics of clipped linear quadratic regulator (LQR). The control parameters are derived from optimal modal viscous damping and corrected in order to guarantee that both the equivalent viscous damping coefficient and the equivalent stiffness coefficient of the semi-active cable damper force are equal to their desired counterparts. The collocated control solution with corrected control parameters is numerically validated by free decay tests of the first four cable modes and combinations of these modes. The results of the single-harmonic tests demonstrate that the novel approach yields 1.86 times more cable damping than optimal modal viscous damping and 1.87 to 2.33 times more damping compared to a passive oil damper whose viscous damper coefficient is optimally tuned to the targeted mode range of the first four modes. The improvement in case of the multi-harmonic vibration tests, i.e. when modes 1 and 3 and modes 2 and 4 are vibrating at the same time, is between 1.55 and 3.81. The results also show that these improvements are obtained almost independent of the cable anti-node amplitude. Thus, the proposed approximate real-time applicable collocated semi-active control solution which can be realized by magnetorheological dampers represents a promising tool for the efficient mitigation of stay cable vibrations.

  18. Multi-Mode Estimation for Small Fixed Wing Unmanned Aerial Vehicle Localization Based on a Linear Matrix Inequality Approach

    PubMed Central

    Elzoghby, Mostafa; Li, Fu; Arafa, Ibrahim. I.; Arif, Usman

    2017-01-01

    Information fusion from multiple sensors ensures the accuracy and robustness of a navigation system, especially in the absence of global positioning system (GPS) data which gets degraded in many cases. A way to deal with multi-mode estimation for a small fixed wing unmanned aerial vehicle (UAV) localization framework is proposed, which depends on utilizing a Luenberger observer-based linear matrix inequality (LMI) approach. The proposed estimation technique relies on the interaction between multiple measurement modes and a continuous observer. The state estimation is performed in a switching environment between multiple active sensors to exploit the available information as much as possible, especially in GPS-denied environments. Luenberger observer-based projection is implemented as a continuous observer to optimize the estimation performance. The observer gain might be chosen by solving a Lyapunov equation by means of a LMI algorithm. Convergence is achieved by utilizing the linear matrix inequality (LMI), based on Lyapunov stability which keeps the dynamic estimation error bounded by selecting the observer gain matrix (L). Simulation results are presented for a small UAV fixed wing localization problem. The results obtained using the proposed approach are compared with a single mode Extended Kalman Filter (EKF). Simulation results are presented to demonstrate the viability of the proposed strategy. PMID:28420214

  19. Multi-species sensing using multi-mode absorption spectroscopy with mid-infrared interband cascade lasers

    NASA Astrophysics Data System (ADS)

    O'Hagan, S.; Northern, J. H.; Gras, B.; Ewart, P.; Kim, C. S.; Kim, M.; Merritt, C. D.; Bewley, W. W.; Canedy, C. L.; Vurgaftman, I.; Meyer, J. R.

    2016-06-01

    The application of an interband cascade laser, ICL, to multi-mode absorption spectroscopy, MUMAS, in the mid-infrared region is reported. Measurements of individual mode linewidths of the ICL, derived from the pressure dependence of lineshapes in MUMAS signatures of single, isolated, lines in the spectrum of HCl, were found to be in the range 10-80 MHz. Multi-line spectra of methane were recorded using spectrally limited bandwidths, of approximate width 27 cm-1, defined by an interference filter, and consist of approximately 80 modes at spectral locations spanning the 100 cm-1 bandwidth of the ICL output. Calibration of the methane pressures derived from MUMAS data using a capacitance manometer provided measurements with an uncertainty of 1.1 %. Multi-species sensing is demonstrated by the simultaneous detection of methane, acetylene and formaldehyde in a gas mixture. Individual partial pressures of the three gases are derived from best fits of model MUMAS signatures to the data with an experimental error of 10 %. Using an ICL, with an inter-mode interval of ~10 GHz, MUMAS spectra were recorded at pressures in the range 1-10 mbar, and, based on the data, a potential minimum detection limit of the order of 100 ppmv is estimated for MUMAS at atmospheric pressure using an inter-mode interval of 80 GHz.

  20. Photonic crystal film with three alternating layers for simultaneous R, G, B multi-mode photonic band-gaps.

    PubMed

    Park, Byoungchoo; Kim, Mi-Na; Kim, Sun Woong; Ho Park, Jin

    2008-09-15

    We studied 1-dimensional (1-D) photonic crystal (PC) films with three alternating layers to investigate multi-mode photonic band-gaps (PBGs) at red, green, and blue color regions. From simulations, it was shown that PCs with three alternating layered elements of [a/b/c] structure have sharp PBGs at the three color regions with the central wavelengths of 459 nm, 527 nm, and 626 nm, simultaneously. Experimentally, it was proven that red, green, and blue PBGs were generated clearly by the PCs, which were made of multilayers of [SiO(2)/Ta(2)O(5)/TiO(2)], based on the simulation. It was also shown that the measured wavelengths of the PBGs corresponded exactly to those of the simulated results. Moreover, it was demonstrated that a 1-D PC of [a/b/c] structure can be used for making white organic light emitting devices (OLEDs) with improved color rendering index (CRI) for color display or lighting.

  1. Optical fiber calcium ion sensor: development and testing

    NASA Astrophysics Data System (ADS)

    Arora, Monika; Doan, Grace; Anderson, Sonia R.; Nwachukwu, Florence; Plant, Thomas K.

    2003-11-01

    An optical fiber calcium ion sensor is developed through the exploitation of the natural selectivity of the Ca+2 binding properties of the fluorescent probe Calcium Orange (Molecular Probes, Eugene, OR). A multi-mode optical fiber is used to detect calcium in solution. There is a two and a half fold increase observed between a 1 mM EGTA + buffer solution and a 1 mM Ca2+ solution. A variety of different methods of attaching the molecular probe to the end of the fiber are explored.

  2. Optical fiber-based photocathode

    NASA Astrophysics Data System (ADS)

    Cǎsǎndruc, Albert; Bücker, Robert; Kassier, Günther; Miller, R. J. Dwayne

    2016-08-01

    We present the design of a back-illuminated photocathode for electron diffraction experiments based on an optical fiber, and experimental characterization of emitted electron bunches. Excitation light is guided through the fiber into the experimental vacuum chamber, eliminating typical alignment difficulties between the emitter metal and the optical trigger and position instabilities, as well as providing reliable control of the laser spot size and profile. The in-vacuum fiber end is polished and coated with a 30 nm gold (Au) layer on top of 3 nm of chromium (Cr), which emits electrons by means of single-photon photoemission when femtosecond pulses in the near ultraviolet (257 nm) are fed into the fiber on the air side. The emission area can be adjusted to any value between a few nanometers (using tapered fibers) and the size of a multi-mode fiber core (100 μm or larger). In this proof-of-principle experiment, two different types of fibers were tested, with emission spot diameters of 50 μm and 100 μm, respectively. The normalized thermal electron beam emittance (TE) was measured by means of the aperture scan technique, and a TE of 4.0 π nm was measured for the smaller spot diameter. Straightforward enhancements to the concept allowed to demonstrate operation in an electric field environment of up to 7 MV/m.

  3. The radiation hardness of specific multi-mode and single-mode optical fibres at -25°C beyond a full SLHC dose to a dose of 500 kGy(Si)

    NASA Astrophysics Data System (ADS)

    Huffman, B. T.; Issever, C.; Ryder, N. C.; Weidberg, A. R.

    2010-11-01

    The optical fibres that will be used in SLHC detectors will be exposed to high doses and low temperatures in the inner detectors. A number of Single-Mode (SM) and Multi-Mode (MM) fibres have been tested for radiation hardness by exposure beyond a full SLHC dose to 500 kGy(Si) in the -25°C operating temperatures expected in the upgraded inner detectors. From these measurements conservative estimates of the level of Radiation Induced Absorption (RIA) have been calculated for these fibres in realistic paths through an upgraded inner detector. Two SM fibres have been found whose total calculated RIAs were much lower than the budgeted 1 dB, despite the high dose rates used in the experiment. The RIAs for the DrakaElite Super RadHard Single-Mode Fiber and Fibre X were calculated to be 0.142 and 0.064 dB respectively. Another SM and a MM fibre showed high levels of RIA during the experiment, however they cannot be ruled out as candidate fibres due the the high dose rate of 27 kGy(Si)/hr used.

  4. Multi-mode horn

    NASA Technical Reports Server (NTRS)

    Neilson, Jeffrey M. (Inventor)

    2002-01-01

    A horn has an input aperture and an output aperture, and comprises a conductive inner surface formed by rotating a curve about a central axis. The curve comprises a first arc having an input aperture end and a transition end, and a second arc having a transition end and an output aperture end. When rotated about the central axis, the first arc input aperture end forms an input aperture, and the second arc output aperture end forms an output aperture. The curve is then optimized to provide a mode conversion which maximizes the power transfer of input energy to the Gaussian mode at the output aperture.

  5. Low-loss single-mode operation in silicon multi-mode arrayed waveguide grating with a double-etched inverse taper structure

    NASA Astrophysics Data System (ADS)

    Park, Jaegyu; Kwack, Myung-Joon; Joo, Jiho; Kim, Gyungock

    2017-08-01

    We investigate the single-mode operation in a silicon arrayed multi-mode waveguide grating. By introducing a double-etched structure at the boundary of a star coupler with inverse-tapered waveguides (WGs), the suppression of the mode-coupling between adjacent arrayed multi-mode WGs, and the adiabatic optical mode conversion between a FPR (free propagation region) and arrayed WGs can be achieved with a reduced phase error of the arrayed WGs. The fabricated four-channel Si arrayed waveguide grating (AWG) demonstrates a good performance level, such as a low insertion loss of 0.61 dB (0.73 dB) and low adjacent crosstalk less than -31.3 dB (-32.2 dB) for transverse-electric (TE) (transverse-magnetic, TM) polarization, in the range of ˜1300 nm wavelength.

  6. Whimsicality of multi-mode Hasegawa space-charge waves in a complex plasma containing collision-dominated electrons and streaming ions

    NASA Astrophysics Data System (ADS)

    Lee, Myoung-Jae; Jung, Young-Dae

    2017-09-01

    The influence of collision-dominated electrons on multi-mode Hasegawa space-charge waves are investigated in a complex plasma containing streaming ions. The dispersion relation for the multi-mode Hasegawa space-charge wave propagating in a cylindrical waveguide filled with dusty plasma containing collision-dominated electrons and streaming ions is derived by using the fluid equations and Poisson’s equation which lead to a Bessel equation. By the boundary condition, the roots of the Bessel function would characterize the property of space-charge wave propagation. It is found that two solutions exist for wave frequency, which are affected by the radius of waveguide and the roots of the Bessel function. The damping and growing modes are found to be enhanced by an increase of the radius. However, an increase of electron collision frequency would suppress the damping and the growing modes of the propagating space-charge wave in a cylindrical waveguide plasma.

  7. The backscattering characteristics of wetland vegetation and water-level changes detection using multi-mode SAR: A case study

    NASA Astrophysics Data System (ADS)

    Zhang, Meimei; Li, Zhen; Tian, Bangsen; Zhou, Jianmin; Tang, Panpan

    2016-03-01

    A full understanding of the backscattering characteristics of wetlands is necessary for the analysis of the hydrological conditions. In this study, a temporal set of synthetic aperture radar (SAR) imagery, acquired at different frequencies, polarizations and incidence angles over the coastal wetlands of the Liaohe River Delta, China, were used to characterize seasonal variations in radar backscattering coefficient for reed marshes and rice fields. The combination of SAR backscattering intensity and an optical-based normalized difference vegetation index (NDVI) for long time series can provide additional insight into vegetation structural and its hydrological states. After identifying the factors that induce the backscattering and scattering mechanism changes, detailed analysis of L-band ALOS PALSAR interferometric SAR (InSAR) imagery was conducted to study water-level changes under different environmental conditions. In addition, ENVISAT altimetry was used to validate the accuracy of the water-level changes estimated using the InSAR technique-this is an effective tool instead of sparsely distributed gauge stations for the validation. Our study demonstrates that L-band SAR data with horizontal polarization is particularly suitable for the extraction of water-level changes in the study area; however, vertically-polarized C-band data may also be useful where the density of herbaceous vegetation is low at the initial stage. It is also shown that integrated analysis of the backscattering mechanism and interferometric characteristics using multi-mode SAR can considerably enhance the reliability of the water-level retrieval scheme and better capture the spatial distribution of hydrological patterns.

  8. Lithosphere-Asthenosphere Transition, Mid-Lithosphere Discontinuity and Radial Anisotropy from Multi-mode Surface Wave Tomography

    NASA Astrophysics Data System (ADS)

    Yoshizawa, K.; Kennett, B. L. N.

    2015-12-01

    Seismic surface waves are the major source of information to delineate the lateral heterogeneity and anisotropy in the upper mantle. S-wave radial anisotropy representing the difference between SV and SH velocities is often discussed with the seismic properties of the lithosphere-asthenosphere transition (LAT) and the mid-lithosphere discontinuity (MLD). Such boundaries have been studied well by body-wave receiver functions, which have a good sensitivity to the sharpness of boundaries. Surface waves are rather insensitive to the boundary sharpness, but can delineate the spatial distributions of shear wave speeds and radial anisotropy in the upper mantle, which can be alternative constraints on LAT and MLD. We have recently constructed a radially anisotropic 3-D S wave speed model of the Australian continent from multi-mode Love and Rayleigh waves with enhanced ray coverage. In the inversions for S-wave radial anisotropy, we can use either parameterizations for SH and SV velocities, or for dimensionless radially anisotropic parameter ξ=(Vsh/Vsv)2. Both are theoretically the same, but this difference causes non-negligible effects on the estimated radial anisotropy, mainly due to the different sensitivities of Love-wave phase speeds to the structural parameters. Synthetic experiments and data variance reductions suggest the former is the better choice. The LAT throughout the continent can be estimated by the vertical velocity gradient of the isotropic S-wave model. The radial anisotropy with the suitable model parameterization shows strong anisotropy with faster SH velocity in the asthenosphere, suggesting the influence of strong shear beneath the fast drifting Australian continent. We can also identify the clear vertical changes in the radial anisotropy profiles at the MLD depth estimated from earlier receiver function studies in cratonic regions, which can be a key to elucidate the enigmatic MLD in the continental lithosphere.

  9. Multi-Mode Surface-Waveform Tomography of the Pacific Region: Model Validation and the Lithospheric Cooling Signature.

    NASA Astrophysics Data System (ADS)

    Maggi, A.; Tromp, J.; Debayle, E.; Barruol, G.

    2005-12-01

    We present an anisotropic Sv-wave speed tomographic model for the Pacific Ocean region derived from multi-mode waveform inversion of more than 56,000 vertical component seismograms. Most of the data are from the Global Seismic Network, but we include important data from ten broadband seismographs deployed in French Polynesia as part of the Polynesian Lithosphere and Upper Mantle Experiment. This extra data has improved lateral resolution in the south Pacific region, leading to the identification of localized, vertically trending low velocity anomalies associated with the Society and Macdonald hot-spots. An age-dependent average cross-section of our tomographic model shows the lithosphere thickening and cooling with increasing age as predicted by a purely diffusive cooling mechanism. The tomography was performed assuming 2D frequency-independent Gaussian-shaped sensitivity kernels around the surface wave ray-paths, and ray-theoretical depth dependence of the surface wave sensitivity. We validate the 3D tomographic model by calculating full 3D synthetic seismograms using the spectral element method. We estimate the quality of our tomographic inversion by making multi-taper phase and amplitude measurements of the differences between observed seismograms and 3D synthetics. Preliminary inversion of such measurements made on fundamental mode surface waves indicates that the residual discrepancies between our 3D tomographic model and the real Earth structure are localized in regions of strong upper mantle heterogeneity (e.g. subduction zones), for which the ray-theoretical approximations made during the tomographic inversion are most likely to break down.

  10. Catastrophic facet and bulk degradation in high power multi-mode InGaAs strained quantum well single emitters

    NASA Astrophysics Data System (ADS)

    Sin, Yongkun; Presser, Nathan; Foran, Brendan; Ives, Neil; Moss, Steven C.

    2009-02-01

    Extensive investigations by a number of groups have identified catastrophic sudden degradation as the main failure mode in both single-mode and multi-mode InGaAs-AlGaAs strained quantum well (QW) lasers. Significant progress made in performance characteristics of broad-area InGaAs strained QW single emitters in recent years has led to an optical output power of over 20W and a power conversion efficiency of over 70% under CW operation. However, unlike 980nm single-mode lasers that have shown high reliability operation under a high optical power density of ~50MW/cm2, broad-area lasers have not achieved the same level of reliability even under a much lower optical power density of ~5MW/cm2. This paper investigates possible mechanisms that prevent broad-area lasers from achieving high reliability operation by performing accelerated lifetests of these devices and in-depth failure mode analyses of degraded devices with various destructive and non-destructive techniques including EBIC, FIB, and HR-TEM techniques. The diode lasers that we have investigated are commercial MOCVD-grown broad-area strained InGaAs single QW lasers at ~975nm. Both passivated and unpassivated broad-area lasers were studied that yielded catastrophic failures at the front facet and also in the bulk. To investigate the role that generation and propagation of defects plays in degradation processes via recombination enhanced defect reaction (REDR), EBIC was employed to study dark line defects in degraded lasers, failed under different stress conditions, and the correlation between DLDs and stress levels is reported. FIB was then employed to prepare TEM samples from the DLD areas for cross-sectional HR-TEM analysis.

  11. Role of multi-mode ultrasound in the diagnosis of level 4 BI-RADS breast lesions and Logistic regression model

    PubMed Central

    Leng, Xiaoling; Huang, Guofu; Yao, Lanhui; Ma, Fucheng

    2015-01-01

    Objective: This study is to investigate the diagnostic role of multi-mode ultrasound in level 4 BI-RADS breast lesions and to establish a Logistic regression model. Methods: Totally 179 patients with 182 sites of breast lesions were enrolled in this study. Preoperatively, the examinations of routine ultrasonography, elastography, contrast-enhanced ultrasonography and three-dimensional color Doppler were performed. Postoperatively, the breast lesions were diagnosed as benign and malignant lesions according to pathological results. Diagnostic indicators of each ultrasound analysis were determined and compared. The relationship between these diagnostic indicators and the benign and malignant features of breast lesions was analyzed by single factor analysis. Logistic regression model was established. Results: The diagnostic indicators with high sensitivity and specificity were tumor edge, enhanced range and score of elastography. Four factors of tumor edge, enhanced order, contrast mode and score of elastography were related with the benign and malignant features of breast lesions. The prediction model was Logit (P) = 0.636 + 4.471X1 + 4.337X2 + 3.753X3 + 3.014X4 + 2.525X5 + 2.105X6. Likelihood ratio test showed that the model was statistically significant (χ2 = 161.876, P < 0.0001). This model could effectively distinguish between benign and malignant tumors (R2 = 0.813, prediction accuracy 92.3%). The differences in sensitivity and specificity between multi-mode ultrasound diagnosis and routine ultrasound diagnosis were statistically significant (P < 0.001). However, there was no significant difference between Logistic regression model and multi-mode ultrasound diagnosis. Conclusion: Multi-mode ultrasound and Logistic regression model are more effective in diagnosing level 4 BI-RADS breast lesions. PMID:26629092

  12. Spectral coarse grained controllability of complex networks

    NASA Astrophysics Data System (ADS)

    Wang, Pei; Xu, Shuang

    2017-07-01

    With the accumulation of interaction data from various systems, a fundamental question in network science is how to reduce the sizes while keeping certain properties of complex networks. Combined the spectral coarse graining theory and the structural controllability of complex networks, we explore the structural controllability of undirected complex networks during coarse graining processes. We evidence that the spectral coarse grained controllability (SCGC) properties for the Erdös-Rényi (ER) random networks, the scale-free (SF) random networks and the small-world (SW) random networks are distinct from each other. The SW networks are very robust, while the SF networks are sensitive during the coarse graining processes. As an emergent properties for the dense ER networks, during the coarse graining processes, there exists a threshold value of the coarse grained sizes, which separates the controllability of the reduced networks into robust and sensitive to coarse graining. Investigations on some real-world complex networks indicate that the SCGC properties are varied among different categories and different kinds of networks, some highly organized social or biological networks are more difficult to be controlled, while many man-made power networks and infrastructure networks can keep the controllability properties during the coarse graining processes. Furthermore, we speculate that the SCGC properties of complex networks may depend on their degree distributions. The associated investigations have potential implications in the control of large-scale complex networks, as well as in the understanding of the organization of complex networks.

  13. Mode coupling in multimode plastic optical fiber

    NASA Astrophysics Data System (ADS)

    Wang, Jing

    1999-10-01

    In this thesis, we report the results of our experimental and theoretical studies of mode coupling in multi-mode optical fibers. We demonstrate that strong mode coupling in poly(methyl methacrylate) (PMMA) based multi-mode plastic optical fibers (POFs) effectively increases the bandwidth performance by a factor of as much as an order of magnitude. We investigate in detail the physical mechanisms of mode coupling. The most important feature of an optical fiber waveguide is its bandwidth, which defines its information carrying capacity. A major limitation on the bandwidth of multi- mode glass and plastic optical fibers is modal dispersion, in which different optical modes propagate at different velocities and the dispersion grows linearly with length. Modal dispersion in an optical fiber waveguide is reduced through mode coupling by allowing the energy packets of a signal pulse at different times to occupy different modes as they are propagating down the waveguide. With mode coupling, pulse broadening varies only as a characteristic square root function of the fiber length as opposed to following the usual linear dependence The bandwidths of both step index (SI) and graded index (GI) POF samples are carefully measured in the time domain and determined to be 80 +/- 10 MHz per 100m for SI POF and 3.0 +/- 0.4 GHz per 100m for GI POF. The index profiles are first directly measured by standard high accuracy techniques, such as the near field method, the refracted near field ray method, and the transverse interferometric method (TIM), and then probed with the highly sensitive differential mode delay (DMD) measurement. We developed a highly efficient numerical methodology based on the Streifer-Kurtz WKB theory for solving the scalar wave equation in fiber waveguides and implemented the new method in MathematicaTM to simulate fiber optical transmission characteristics for an arbitrary given index profile, such as the DMD profile, impulse response, and bandwidth performance

  14. Numerical modeling of multi-mode active control of turbofan tonal noise using a boundary element method

    NASA Astrophysics Data System (ADS)

    Ireland, Laralee Gordon

    A numerical model was developed to investigate the possibility of implementing active control (ANC) to minimize noise radiation from high-bypass turbofan engines. Previous experimental work on the NASA Glenn Research Center active noise control fan (ANCF) was encouraging, but the question remained whether the modal approach investigated could be effective on real engines. The engine model developed for this research project uses an indirect boundary element method, implemented with Sysnoise, and a multi-mode Newton's algorithm, implemented with MATLAB(TM), to simulate the active control. Noise from the inlet was targeted. Both the experimental and numerical results based on the NASA ANCF simplified cylindrical engine geometry indicate overall reductions in the m = 2 component of the noise. Reductions obtained at the numerical sensor rings range from 17 dB to 63 dB and at a plane in the duct inlet, -8 dB to 33 dB. Rings mounted on the inlet duct are unable to accurately predict the total reduction of the inlet field, but the controller is still able to effectively reduce the total acoustic field. Generally, one sensor ring and one actuator ring per propagating mode were necessary to control the inlet field. At frequencies close to the cut-off frequency of a mode, an additional sensor and actuator ring were needed to adequately control the inlet field due to the evanescent mode. A more realistic, but still axisymmetric, engine geometry based on the GE CF6-80C engine was developed and the same algorithm used. Reductions obtained at the sensor rings range from 4 dB to 56 dB and at the duct inlet plane, from 12 dB to 26 dB. The overall far field noise radiation from the engine remained unchanged (0.4 dB) or decreased slightly (3.6 dB). The inlet noise was controlled at all frequencies but the noise from the exhaust was increased. The effect of inlet control on the exhaust radiation suggests the need for a controller that targets both the inlet and exhaust noise

  15. Pump and signal combiner for bi-directional pumping of all-fiber lasers and amplifiers.

    PubMed

    Theeg, Thomas; Sayinc, Hakan; Neumann, Jörg; Overmeyer, Ludger; Kracht, Dietmar

    2012-12-17

    We developed an all-fiber component with a signal feedthrough capable of combining up to 6 fiber-coupled multi-mode pump sources to a maximum pump power of 400 W at efficiencies in the range of 89 to 95%, providing the possibility of transmitting a high power signal in forward and in reverse direction. Hence, the fiber combiner can be implemented in almost any fiber laser or amplifier architecture. The complete optical design of the combiner was developed based on ray tracing simulations and confirmed by experimental results.

  16. Development of an instrumentation system for measurement of degradation of lubricating oil using optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Laskar, S.; Bordoloi, S.

    2016-01-01

    This paper presents an instrumentation system to measure the degradation in lubricating oil using a bare, tapered and bent multi-mode optical fiber (BTBMOF) sensor probe and a temperature probe. The sensor system consists of (i) a bare, tapered and bent multi-mode optical fiber (BTBMOF) as optical sensor along with a laser source and a LDR (Light Dependent Resistor) as detector (ii) a temperature sensor (iii) a ATmega microcontroller based data acquisition system and (iv) a trained ANN for processing and calibration. The BTBMOF sensor and the temperature sensor are used to provide the measure of refractive index (RI) and the temperature of a lubricating oil sample. A microcontroller based instrumentation system with trained ANN algorithm has been developed to determine the degradation of the lubricating oil sample by sampling the readings of the optical fiber sensor, and the temperature sensor.

  17. Peculiar Traits of Coarse AP (Briefing Charts)

    DTIC Science & Technology

    2014-12-01

    at differing rates due to pressure and temperature influences in both isolated crystals and solid propellant combustions. Consolidated coarse AP...phase AP is a primary actor during combustions. At very high pressures AP self combustion exhibits differential recession rates depending on whether...different reaction rates are also observed between low and high pressure confinements. In solid propellants coarse AP promotes dark zone combustion, low

  18. Coarse-graining methods for computational biology.

    PubMed

    Saunders, Marissa G; Voth, Gregory A

    2013-01-01

    Connecting the molecular world to biology requires understanding how molecular-scale dynamics propagate upward in scale to define the function of biological structures. To address this challenge, multiscale approaches, including coarse-graining methods, become necessary. We discuss here the theoretical underpinnings and history of coarse-graining and summarize the state of the field, organizing key methodologies based on an emerging paradigm for multiscale theory and modeling of biomolecular systems. This framework involves an integrated, iterative approach to couple information from different scales. The primary steps, which coincide with key areas of method development, include developing first-pass coarse-grained models guided by experimental results, performing numerous large-scale coarse-grained simulations, identifying important interactions that drive emergent behaviors, and finally reconnecting to the molecular scale by performing all-atom molecular dynamics simulations guided by the coarse-grained results. The coarse-grained modeling can then be extended and refined, with the entire loop repeated iteratively if necessary.

  19. Curvature function and coarse graining

    NASA Astrophysics Data System (ADS)

    Díaz-Marín, Homero; Zapata, José A.

    2010-12-01

    A classic theorem in the theory of connections on principal fiber bundles states that the evaluation of all holonomy functions gives enough information to characterize the bundle structure (among those sharing the same structure group and base manifold) and the connection up to a bundle equivalence map. This result and other important properties of holonomy functions have encouraged their use as the primary ingredient for the construction of families of quantum gauge theories. However, in these applications often the set of holonomy functions used is a discrete proper subset of the set of holonomy functions needed for the characterization theorem to hold. We show that the evaluation of a discrete set of holonomy functions does not characterize the bundle and does not constrain the connection modulo gauge appropriately. We exhibit a discrete set of functions of the connection and prove that in the abelian case their evaluation characterizes the bundle structure (up to equivalence), and constrains the connection modulo gauge up to "local details" ignored when working at a given scale. The main ingredient is the Lie algebra valued curvature function F_S (A) defined below. It covers the holonomy function in the sense that exp {F_S (A)} = Hol(l= partial S, A).

  20. Curvature function and coarse graining

    SciTech Connect

    Diaz-Marin, Homero; Zapata, Jose A.

    2010-12-15

    A classic theorem in the theory of connections on principal fiber bundles states that the evaluation of all holonomy functions gives enough information to characterize the bundle structure (among those sharing the same structure group and base manifold) and the connection up to a bundle equivalence map. This result and other important properties of holonomy functions have encouraged their use as the primary ingredient for the construction of families of quantum gauge theories. However, in these applications often the set of holonomy functions used is a discrete proper subset of the set of holonomy functions needed for the characterization theorem to hold. We show that the evaluation of a discrete set of holonomy functions does not characterize the bundle and does not constrain the connection modulo gauge appropriately. We exhibit a discrete set of functions of the connection and prove that in the abelian case their evaluation characterizes the bundle structure (up to equivalence), and constrains the connection modulo gauge up to ''local details'' ignored when working at a given scale. The main ingredient is the Lie algebra valued curvature function F{sub S}(A) defined below. It covers the holonomy function in the sense that expF{sub S}(A)=Hol(l={partial_derivative}S,A).

  1. SU-E-I-23: Design and Clinical Application of External Marking Body in Multi- Mode Medical Images Registration and Fusion

    SciTech Connect

    Chen, Z; Gong, G

    2014-06-01

    Purpose: To design an external marking body (EMB) that could be visible on computed tomography (CT), magnetic resonance (MR), positron emission tomography (PET) and single-photon emission computed tomography (SPECT) images and to investigate the use of the EMB for multiple medical images registration and fusion in the clinic. Methods: We generated a solution containing paramagnetic metal ions and iodide ions (CT'MR dual-visible solution) that could be viewed on CT and MR images and multi-mode image visible solution (MIVS) that could be obtained by mixing radioactive nuclear material. A globular plastic theca (diameter: 3–6 mm) that mothball the MIVS and the EMB was brought by filling MIVS. The EMBs were fixed on the patient surface and CT, MR, PET and SPECT scans were obtained. The feasibility of clinical application and the display and registration error of EMB among different image modalities were investigated. Results: The dual-visible solution was highly dense on CT images (HU>700). A high signal was also found in all MR scanning (T1, T2, STIR and FLAIR) images, and the signal was higher than subcutaneous fat. EMB with radioactive nuclear material caused a radionuclide concentration area on PET and SPECT images, and the signal of EMB was similar to or higher than tumor signals. The theca with MIVS was clearly visible on all the images without artifact, and the shape was round or oval with a sharp edge. The maximum diameter display error was 0.3 ± 0.2mm on CT and MRI images, and 1.0 ± 0.3mm on PET and SPECT images. In addition, the registration accuracy of the theca center among multi-mode images was less than 1mm. Conclusion: The application of EMB with MIVS improves the registration and fusion accuracy of multi-mode medical images. Furthermore, it has the potential to ameliorate disease diagnosis and treatment outcome.

  2. Fiber lasers for material processing

    NASA Astrophysics Data System (ADS)

    Shiner, Bill

    2005-03-01

    Low power fiber lasers began entering the commercial markets in the early 1990s. Since their introduction, fiber lasers have rapidly progressed in power levels level with greatly improved beam quality to the point where they now exceed any other commercial material processing laser. These lasers, with single mode operation to 1 kilowatt and multi-mode operation to beyond 20 kilowatts, have high wall plug efficiency, an extremely compact footprint, are maintenance free and have a predicted diode life beyond 100,000 hours of continuous operation. Fiber lasers are making inroads into the scientific, medical, government, and in particular, material processing markets. These lasers have greatly expanded the application umbrella due to their unparallel performance combined with the ability to operate at different wavelengths, address remote applications and be propagated great distances in fiber. In the material processing markets, fiber lasers are rapidly gaining share in the automotive, microelectronic, medical device and marking markets, to name a few. The single mode lasers are redefining process parameters that have been accepted for decades. The high brightness multimode-kilowatt class lasers are achieving speeds and depths greater than comparable powered conventional lasers while providing the only commercial material processing lasers operating beyond 6 kilowatts at the 1 micron region.

  3. Convergent Coarseness Regulation for Segmented Images

    SciTech Connect

    Paglieroni, D W

    2004-05-27

    In segmentation of remotely sensed images, the number of pixel classes and their spectral representations are often unknown a priori. Even with prior knowledge, pixels with spectral components from multiple classes lead to classification errors and undesired small region artifacts. Coarseness regulation for segmented images is proposed as an efficient novel technique for handling these problems. Beginning with an over-segmented image, perceptually similar connected regions are iteratively merged using a method reminiscent of region growing, except the primitives are regions, not pixels. Interactive coarseness regulation is achieved by specifying the area {alpha} of the largest region eligible for merging. A region with area less than {alpha} is merged with the most spectrally similar connected region, unless the regions are perceived as spectrally dissimilar. In convergent coarseness regulation, which requires no user interaction, {alpha} is specified as the total number of pixels in the image, and the coarseness regulation output converges to a steady-state segmentation that remains unchanged as {alpha} is further increased. By applying convergent coarseness regulation to AVIRIS, IKONOS and DigitalGlobe images, and quantitatively comparing computer-generated segmentations to segmentations generated manually by a human analyst, it was found that the quality of the input segmentations was consistently and dramatically improved.

  4. Quasiclassical coarse graining and thermodynamic entropy

    SciTech Connect

    Gell-Mann, Murray; Hartle, James B.

    2007-08-15

    Our everyday descriptions of the universe are highly coarse grained, following only a tiny fraction of the variables necessary for a perfectly fine-grained description. Coarse graining in classical physics is made natural by our limited powers of observation and computation. But in the modern quantum mechanics of closed systems, some measure of coarse graining is inescapable because there are no nontrivial, probabilistic, fine-grained descriptions. This essay explores the consequences of that fact. Quantum theory allows for various coarse-grained descriptions, some of which are mutually incompatible. For most purposes, however, we are interested in the small subset of 'quasiclassical descriptions' defined by ranges of values of averages over small volumes of densities of conserved quantities such as energy and momentum and approximately conserved quantities such as baryon number. The near-conservation of these quasiclassical quantities results in approximate decoherence, predictability, and local equilibrium, leading to closed sets of equations of motion. In any description, information is sacrificed through the coarse graining that yields decoherence and gives rise to probabilities for histories. In quasiclassical descriptions, further information is sacrificed in exhibiting the emergent regularities summarized by classical equations of motion. An appropriate entropy measures the loss of information. For a 'quasiclassical realm' this is connected with the usual thermodynamic entropy as obtained from statistical mechanics. It was low for the initial state of our universe and has been increasing since.

  5. Graphene-based side-polished optical fiber amplifier.

    PubMed

    Karimi, Mohammad; Ahmadi, Vahid; Ghezelsefloo, Masoud

    2016-12-20

    We demonstrate a novel design for optical fiber amplifiers, utilizing side-polished fibers with a single-layer graphene overlay as the active medium and carrier injection in the graphene layer to provide the required inversion. We study the effects of an electrically induced graphene p-i-n heterojunction in the forward bias regime on optical modes of side-polished fibers and show that gain values of 0.51, 1.81, and 1.79 dB/cm for wavelengths 1064, 1330, and 1550 nm can be obtained for single-mode side-polished fibers. Our results show that in multi-mode side-polished fibers, higher order modes experience higher values of gain, and gain can be increased by increasing polished depth. The proposed system is a tunable wideband optical amplifier that can operate for wavelengths larger than 1000 nm.

  6. Who acquires infection from whom and how? Disentangling multi-host and multi-mode transmission dynamics in the ‘elimination’ era

    PubMed Central

    Borlase, Anna; Rudge, James W.

    2017-01-01

    Multi-host infectious agents challenge our abilities to understand, predict and manage disease dynamics. Within this, many infectious agents are also able to use, simultaneously or sequentially, multiple modes of transmission. Furthermore, the relative importance of different host species and modes can itself be dynamic, with potential for switches and shifts in host range and/or transmission mode in response to changing selective pressures, such as those imposed by disease control interventions. The epidemiology of such multi-host, multi-mode infectious agents thereby can involve a multi-faceted community of definitive and intermediate/secondary hosts or vectors, often together with infectious stages in the environment, all of which may represent potential targets, as well as specific challenges, particularly where disease elimination is proposed. Here, we explore, focusing on examples from both human and animal pathogen systems, why and how we should aim to disentangle and quantify the relative importance of multi-host multi-mode infectious agent transmission dynamics under contrasting conditions, and ultimately, how this can be used to help achieve efficient and effective disease control. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’. PMID:28289259

  7. Time-bin entangled photon pairs from spontaneous parametric down-conversion pumped by a cw multi-mode diode laser.

    PubMed

    Kwon, Osung; Park, Kwang-Kyoon; Ra, Young-Sik; Kim, Yong-Su; Kim, Yoon-Ho

    2013-10-21

    Generation of time-bin entangled photon pairs requires the use of the Franson interferometer which consists of two spatially separated unbalanced Mach-Zehnder interferometers through which the signal and idler photons from spontaneous parametric down-conversion (SPDC) are made to transmit individually. There have been two SPDC pumping regimes where the scheme works: the narrowband regime and the double-pulse regime. In the narrowband regime, the SPDC process is pumped by a narrowband cw laser with the coherence length much longer than the path length difference of the Franson interferometer. In the double-pulse regime, the longitudinal separation between the pulse pair is made equal to the path length difference of the Franson interferometer. In this paper, we propose another regime by which the generation of time-bin entanglement is possible and demonstrate the scheme experimentally. In our scheme, differently from the previous approaches, the SPDC process is pumped by a cw multi-mode (i.e., short coherence length) laser and makes use of the coherence revival property of such a laser. The high-visibility two-photon Franson interference demonstrates clearly that high-quality time-bin entanglement source can be developed using inexpensive cw multi-mode diode lasers for various quantum communication applications.

  8. Coarse-grained short-range correlations

    NASA Astrophysics Data System (ADS)

    Simo, I. Ruiz; Pérez, R. Navarro; Amaro, J. E.; Ruiz Arriola, E.

    2017-05-01

    We develop a scheme to take into account the effects of short-range nucleon-nucleon correlations in the nucleon-pair wave function by solving the Bethe-Goldstone equation for a coarse-grained delta shell potential in S -wave configuration. The S -wave delta shell potential has been adjusted to reproduce the 1S0 phase shifts of the AV18 potential for this partial wave up to 2 GeV in the laboratory kinetic energy. We show that a coarse-grained potential can describe the high momentum tail of the back-to-back correlated pairs and the G matrix in momentum space. We discuss the easiness and robustness of the calculation in coordinate space and the future improvements and utilities of this model. This work suggests the possibility of using perturbation theory for describing the short-range correlations and, related to this, to substitute the G matrix by an appropriate coarse-grained potential.

  9. Reliability of single-mode and multi-mode high-power semiconductor lasers at eye-safe wavelengths

    NASA Astrophysics Data System (ADS)

    Stakelon, T.; Lucas, J.; Osowski, M.; Lammert, R.; Moon, S.; Panja, C.; Elarde, V.; Gallup, K.; Hu, W.; Ungar, J.

    2009-02-01

    High power semiconductor lasers with wavelengths in the eye-safer region have application to a variety of defense, medical and industrial applications. We report on the reliability of high power multimode and single mode InGaAsP/InP diode lasers with wavelengths in the range 1320 to 1550 nm in a variety of configurations, including single-chip, conduction-cooled arrays, arrays incorporating internal diffraction gratings, master-oscillator power amplifiers, and fiber-coupled modules of the above. In all cases we show very low rates of degradation in optical power and the absence of sudden failure from catastrophic optical damage or from laser-package interactions.

  10. Sampling coarse woody debris along spoked transects

    Treesearch

    Paul C. Van Deusen; Jeffery H. Gove

    2011-01-01

    Line transects are commonly used for sampling coarse woody debris (CWD). The USDA Forest Service Forest Inventory and Analysis programme uses a variant of this method that involves sampling for CWD along transects that radiate from the centre of a circular plot-like spokes on a wheel. A new approach for analysis of data collected with spoked transects is developed....

  11. Early Deterioration of Coarse Woody Debris

    Treesearch

    F.H. Tainter; J.W. McMinn

    1999-01-01

    Coarse woody debris (CWD) is an important structural component of southern forest ecosystems. CWD loading may be affected by different decomposition rates on sites of varying quality. Bolts of red oak and loblolly pine were placed on plots at each of three (hydric, mesic. and xeric) sites at the Savannah River Site and sampled over a 16-week period. Major changes...

  12. Multi-modal label-free imaging based on a femtosecond fiber laser.

    PubMed

    Xie, Ruxin; Su, Jue; Rentchler, Eric C; Zhang, Ziyan; Johnson, Carey K; Shi, Honglian; Hui, Rongqing

    2014-07-01

    We demonstrate multi-mode microscopy based on a single femtosecond fiber laser. Coherent anti-Stokes Raman scattering (CARS), stimulated Raman scattering (SRS) and photothermal images can be obtained simultaneously with this simplified setup. Distributions of lipid and hemoglobin in sliced mouse brain samples and blood cells are imaged. The dependency of signal amplitude on the pump power and pump modulation frequency is characterized, which allows to isolate the impact from different contributions.

  13. Multi-modal label-free imaging based on a femtosecond fiber laser

    PubMed Central

    Xie, Ruxin; Su, Jue; Rentchler, Eric C.; Zhang, Ziyan; Johnson, Carey K.; Shi, Honglian; Hui, Rongqing

    2014-01-01

    We demonstrate multi-mode microscopy based on a single femtosecond fiber laser. Coherent anti-Stokes Raman scattering (CARS), stimulated Raman scattering (SRS) and photothermal images can be obtained simultaneously with this simplified setup. Distributions of lipid and hemoglobin in sliced mouse brain samples and blood cells are imaged. The dependency of signal amplitude on the pump power and pump modulation frequency is characterized, which allows to isolate the impact from different contributions. PMID:25071972

  14. A wavelength tunable ONU transmitter based on multi-mode Fabry-Perot laser and micro-ring resonator for bandwidth symmetric TWDM-PON

    NASA Astrophysics Data System (ADS)

    Gao, Zhensen; Sun, Xiao; Zhang, Kaibin

    2016-02-01

    Wavelength tunable optical transmitter is an essential component for the newly standardized time and wavelength division multiplexed passive optical network (TWDM-PON), where tunable ONU with 10Gb/s bit rate is desired to provide 40Gb/s symmetric bandwidth. In this paper, a novel wavelength tunable optical transmitter is proposed by reusing legacy low speed multi-mode Fabry-Perot laser and connecting it with an integrated photonic chip with two coupled micro-ring resonators to generate a tunable single mode signal based on Vernier effect for 10Gb/s high speed modulation, which makes it as a promising solution for colorless ONU in future symmetric TWDM-PON.

  15. Implementation and flight-test of a multi-mode rotorcraft flight-control system for single-pilot use in poor visibility

    NASA Technical Reports Server (NTRS)

    Hindson, William S.

    1987-01-01

    A flight investigation was conducted to evaluate a multi-mode flight control system designed according to the most recent recommendations for handling qualities criteria for new military helicopters. The modes and capabilities that were included in the system are those considered necessary to permit divided-attention (single-pilot) lowspeed and hover operations near the ground in poor visibility conditions. Design features included mode-selection and mode-blending logic, the use of an automatic position-hold mode that employed precision measurements of aircraft position, and a hover display which permitted manually-controlled hover flight tasks in simulated instrument conditions. Pilot evaluations of the system were conducted using a multi-segment evaluation task. Pilot comments concerning the use of the system are provided, and flight-test data are presented to show system performance.

  16. Observation of multi-mode: Upconversion, downshifting and quantum-cutting emission in Tm3+/Yb3+ co-doped Y2O3 phosphor

    NASA Astrophysics Data System (ADS)

    Yadav, Ranvijay; Singh, S. K.; Verma, R. K.; Rai, S. B.

    2014-04-01

    Micro-crystalline Y2O3 phosphor co-doped with Yb3+/Tm3+ has been synthesized and characterized. The phosphor material gives efficient multimodal emission via downshifting (DS), upconversion (UC), and downconversion (DC)/quantum cutting (QC) luminescence processes. Cross relaxation and co-operative energy transfer (CET) have been ascribed as the possible mechanism for QC; as result of which a UV/blue photon absorbed by Tm3+ splits into two near infrared photons (wavelength range 950-1050 nm) emitted by Yb3+. The Yb3+ concentration dependent ET efficiency and QC efficiency has also been evaluated. Such multi-mode emitting phosphors could have potential applications in increasing the conversion efficiency of solar cells via spectral modification.

  17. Advanced manufacturing technologies for reduced cost and weight in portable ruggedized VIS-IR and multi-mode optical systems for land, sea, and air

    NASA Astrophysics Data System (ADS)

    Sweeney, Michael; Spinazzola, Robert; Morrison, Donald; Macklin, Dennis; Marion, Jared

    2011-06-01

    Homeland security systems, special forces, unmanned aerial vehicles (UAV), and marine patrols require low cost, high performance, multi-mode visible through infrared (VIS-IR) wavelength optical systems to identify and neutralize potential threats that often arise at long ranges and under poor visibility conditions. Long range and wide spectral performance requirements favor reflective optical system design solutions. The limited field of view of such designs can be significantly enhanced by the use of catadioptric optical solutions that utilize molded or diamond point machined VIS-IR lenses downstream from reflective objective optics. A common optical aperture that services multiple modes of field-of-view, operating wavelength, and includes laser ranging and spotting, provides the highest utility and is most ideal for size and weight. Such a design also often requires fast, highly aspheric, reflective, refractive, and sometimes diffractive surfaces using high performance and aggressively light-weighted materials that demand the finest of manufacturing technologies. Visible wavelength performance sets the bar for component optical surface irregularity on the order of 20 nm RMS and surface finishes less than 3.0 nm RMS. Aluminum mirrors and structures can also be precision machined to yield "snap together alignment" or limited compensation assembly approaches to reduce cost and enhance interchangeability. Diamond point turning, die cast and investment cast mirror substrates and structures, computerized optical polishing, mirror replication, lens molding and other advanced manufacturing technologies can all be used to minimize the cost of this type of optical equipment. This paper discusses the tradeoffs among materials and process selection for catadioptric, multi-mode systems that are under development for a variety of DoD and Homeland Security applications. Several examples are profiled to illuminate the confluence of applicable design and manufacturing

  18. Multi-element fiber for space-division multiplexing

    NASA Astrophysics Data System (ADS)

    Sahu, J. K.; Jain, S.; Rancaño, V. J. F.; May-Smith, T. C.; Webb, A.; Petropoulos, P.; Richardson, D. J.

    2013-12-01

    A novel approach of using multi-element fiber (MEF) technology in space-division multiplexing (SDM) systems is presented. This paper reviews the progress in fabrication and characterization of MEF based both ultralow crosstalk transmission and amplifier fibers. Passive 3-element MEFs have been successfully demonstrated for application in telecommunications. An active 5-element MEF amplifier has also been demonstrated in a novel multiport cladding-pumped configuration, in which a central un-doped multi-mode pump fiber-element is surrounded by four Er/Yb-doped active fiber-elements. MEF is compatible with current WDM systems, and there is no need to develop specialized multiplexing/demultiplexing components. Moreover, it offers a smooth upgrade to SDM systems.

  19. Vibration damping with active carbon fiber structures

    NASA Astrophysics Data System (ADS)

    Neugebauer, Reimund; Kunze, Holger; Riedel, Mathias; Roscher, Hans-Jürgen

    2007-04-01

    This paper presents a mechatronic strategy for active reduction of vibrations on machine tool struts or car shafts. The active structure is built from a carbon fiber composite with embedded piezofiber actuators that are composed of piezopatches based on the Macro Fiber Composite (MFC) technology, licensed by NASA and produced by Smart Material GmbH in Dresden, Germany. The structure of these actuators allows separate or selectively combined bending and torsion, meaning that both bending and torsion vibrations can be actively absorbed. Initial simulation work was done with a finite element model (ANSYS). This paper describes how state space models are generated out of a structure based on the finite element model and how controller codes are integrated into finite element models for transient analysis and the model-based control design. Finally, it showcases initial experimental findings and provides an outlook for damping multi-mode resonances with a parallel combination of resonant controllers.

  20. A long uniform taper applied to an all-fiber Tm3+ doped double-clad fiber laser

    NASA Astrophysics Data System (ADS)

    Zhang, Y. J.; Zhong, F. F.; He, W. B.; Zhang, Y.; Wang, Y.; Xu, J.; Ju, Y. L.

    2010-11-01

    A long uniform taper fabricated on a large mode area Tm3+-doped double-clad fiber laser, which was clad-pumped by a laser diode (LD), was found to be an effective wavelength filter while improving the output beam quality and narrowing the line-width significantly. The long uniform taper was fabricated directly on the multi-mode Tm3+-doped fiber by heating and stretching method, and located several centimeters before the output fiber end. By slightly bending the taper section, the output laser spectrum was left with only one peak with a line-width less than 0.5 nm, compared to the multi-peak spectrum with a 5 nm line-width before tapering, indicating that the multi-mode fiber could produce quasi-single wavelength output with a long uniform taper. The beam quality factor M 2 declined from 6.6 to 2.6 compared. Only a slight decrease in slope efficiency, from 19.2 to 17.5%, was observed. The main output wavelength had a blue shift of 8 nm.

  1. Coarse grain forces in star polymer melts.

    PubMed

    Liu, L; den Otter, W K; Briels, W J

    2014-10-21

    An analysis is presented of forces acting on the centers of mass of three-armed star polymers in the molten state. The arms consist of 35 Kremer-Grest beads, which is slightly larger than needed for one entanglement mass. For a given configuration of the centers of mass, instantaneous forces fluctuate wildly around averages which are two orders of magnitude smaller than their root mean square deviations. Average forces are well described by an implicit many-body potential, while pair models fail completely. The fluctuating forces are modelled by means of dynamical variables quantifying the degree of mixing of the various polymer pairs. All functions and parameters in a coarse grain model based on these concepts are obtained from the underlying small scale simulation. The coarse model reproduces both the diffusion coefficient and the shear relaxation modulus. Ways to improve the model suggest themselves on the basis of our findings.

  2. Coarse Grid CFD for underresolved simulation

    NASA Astrophysics Data System (ADS)

    Class, Andreas G.; Viellieber, Mathias O.; Himmel, Steffen R.

    2010-11-01

    CFD simulation of the complete reactor core of a nuclear power plant requires exceedingly huge computational resources so that this crude power approach has not been pursued yet. The traditional approach is 1D subchannel analysis employing calibrated transport models. Coarse grid CFD is an attractive alternative technique based on strongly under-resolved CFD and the inviscid Euler equations. Obviously, using inviscid equations and coarse grids does not resolve all the physics requiring additional volumetric source terms modelling viscosity and other sub-grid effects. The source terms are implemented via correlations derived from fully resolved representative simulations which can be tabulated or computed on the fly. The technique is demonstrated for a Carnot diffusor and a wire-wrap fuel assembly [1]. [4pt] [1] Himmel, S.R. phd thesis, Stuttgart University, Germany 2009, http://bibliothek.fzk.de/zb/berichte/FZKA7468.pdf

  3. Measuring Crack Length in Coarse Grain Ceramics

    NASA Technical Reports Server (NTRS)

    Salem, Jonathan A.; Ghosn, Louis J.

    2010-01-01

    Due to a coarse grain structure, crack lengths in precracked spinel specimens could not be measured optically, so the crack lengths and fracture toughness were estimated by strain gage measurements. An expression was developed via finite element analysis to correlate the measured strain with crack length in four-point flexure. The fracture toughness estimated by the strain gaged samples and another standardized method were in agreement.

  4. Coarse-graining polymers as soft colloids

    NASA Astrophysics Data System (ADS)

    Louis, A. A.; Bolhuis, P. G.; Finken, R.; Krakoviack, V.; Meijer, E. J.; Hansen, J. P.

    2002-04-01

    We show how to coarse-grain polymers in a good solvent as single particles, interacting with density-independent or density-dependent interactions. These interactions can be between the centres of mass, the mid- or end-points of the polymers. We also show how to extend these methods to polymers in poor solvents and mixtures of polymers. Treating polymers as soft colloids can greatly speed up the simulation of complex many-polymer systems, including polymer-colloid mixtures.

  5. Coarse graining flow of spin foam intertwiners

    NASA Astrophysics Data System (ADS)

    Dittrich, Bianca; Schnetter, Erik; Seth, Cameron J.; Steinhaus, Sebastian

    2016-12-01

    Simplicity constraints play a crucial role in the construction of spin foam models, yet their effective behavior on larger scales is scarcely explored. In this article we introduce intertwiner and spin net models for the quantum group SU (2 )k×SU (2 )k, which implement the simplicity constraints analogous to four-dimensional Euclidean spin foam models, namely the Barrett-Crane (BC) and the Engle-Pereira-Rovelli-Livine/Freidel-Krasnov (EPRL/FK) model. These models are numerically coarse grained via tensor network renormalization, allowing us to trace the flow of simplicity constraints to larger scales. In order to perform these simulations we have substantially adapted tensor network algorithms, which we discuss in detail as they can be of use in other contexts. The BC and the EPRL/FK model behave very differently under coarse graining: While the unique BC intertwiner model is a fixed point and therefore constitutes a two-dimensional topological phase, BC spin net models flow away from the initial simplicity constraints and converge to several different topological phases. Most of these phases correspond to decoupling spin foam vertices; however we find also a new phase in which this is not the case, and in which a nontrivial version of the simplicity constraints holds. The coarse graining flow of the BC spin net models indicates furthermore that the transitions between these phases are not of second order. The EPRL/FK model by contrast reveals a far more intricate and complex dynamics. We observe an immediate flow away from the original simplicity constraints; however, with the truncation employed here, the models generically do not converge to a fixed point. The results show that the imposition of simplicity constraints can indeed lead to interesting and also very complex dynamics. Thus we need to further develop coarse graining tools to efficiently study the large scale behavior of spin foam models, in particular for the EPRL/FK model.

  6. Coarse-grained protein molecular dynamics simulations.

    PubMed

    Derreumaux, Philippe; Mousseau, Normand

    2007-01-14

    A limiting factor in biological science is the time-scale gap between experimental and computational trajectories. At this point, all-atom explicit solvent molecular dynamics (MD) are clearly too expensive to explore long-range protein motions and extract accurate thermodynamics of proteins in isolated or multimeric forms. To reach the appropriate time scale, we must then resort to coarse graining. Here we couple the coarse-grained OPEP model, which has already been used with activated methods, to MD simulations. Two test cases are studied: the stability of three proteins around their experimental structures and the aggregation mechanisms of the Alzheimer's Abeta16-22 peptides. We find that coarse-grained isolated proteins are stable at room temperature within 50 ns time scale. Based on two 220 ns trajectories starting from disordered chains, we find that four Abeta16-22 peptides can form a three-stranded beta sheet. We also demonstrate that the reptation move of one chain over the others, first observed using the activation-relaxation technique, is a kinetically important mechanism during aggregation. These results show that MD-OPEP is a particularly appropriate tool to study qualitatively the dynamics of long biological processes and the thermodynamics of molecular assemblies.

  7. Coarse-grained protein molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Derreumaux, Philippe; Mousseau, Normand

    2007-01-01

    A limiting factor in biological science is the time-scale gap between experimental and computational trajectories. At this point, all-atom explicit solvent molecular dynamics (MD) are clearly too expensive to explore long-range protein motions and extract accurate thermodynamics of proteins in isolated or multimeric forms. To reach the appropriate time scale, we must then resort to coarse graining. Here we couple the coarse-grained OPEP model, which has already been used with activated methods, to MD simulations. Two test cases are studied: the stability of three proteins around their experimental structures and the aggregation mechanisms of the Alzheimer's Aβ16-22 peptides. We find that coarse-grained isolated proteins are stable at room temperature within 50ns time scale. Based on two 220ns trajectories starting from disordered chains, we find that four Aβ16-22 peptides can form a three-stranded β sheet. We also demonstrate that the reptation move of one chain over the others, first observed using the activation-relaxation technique, is a kinetically important mechanism during aggregation. These results show that MD-OPEP is a particularly appropriate tool to study qualitatively the dynamics of long biological processes and the thermodynamics of molecular assemblies.

  8. The Theory of Ultra Coarse-graining

    NASA Astrophysics Data System (ADS)

    Voth, Gregory

    2013-03-01

    Coarse-grained (CG) models provide a computationally efficient means to study biomolecular and other soft matter processes involving large numbers of atoms correlated over distance scales of many covalent bond lengths and long time scales. Variational methods based on information from simulations of finer-grained (e.g., all-atom) models, for example the multiscale coarse-graining (MS-CG) and relative entropy minimization methods, provide attractive tools for the systematic development of CG models. However, these methods have important drawbacks when used in the ``ultra coarse-grained'' (UCG) regime, e.g., at a resolution level coarser or much coarser than one amino acid residue per effective CG particle in proteins. This is due to the possible existece of multiple metastable states ``within'' the CG sites for a given UCG model configuration. In this talk I will describe systematic variational UCG methods specifically designed to CG entire protein domains and subdomains into single effective CG particles. This is accomplished by augmenting existing effective particle CG schemes to allow for discrete state transitions and configuration-dependent resolution. Additionally, certain conclusions of this work connect back to single-state force matching and open up new avenues for method development in that area. These results provide a formal statistical mechanical basis for UCG methods related to force matching and relative entropy CG methods and suggest practical algorithms for constructing optimal approximate UCG models from fine-grained simulation data.

  9. Pedagogical Comparison of Five Reactions Performed under Microwave Heating in Multi-Mode versus Mono-Mode Ovens: Diels-Alder Cycloaddition, Wittig Salt Formation, E2 Dehydrohalogenation to Form an Alkyne, Williamson Ether Synthesis, and Fischer Esterification

    ERIC Educational Resources Information Center

    Baar, Marsha R.; Gammerdinger, William; Leap, Jennifer; Morales, Erin; Shikora, Jonathan; Weber, Michael H.

    2014-01-01

    Five reactions were rate-accelerated relative to the standard reflux workup in both multi-mode and mono-mode microwave ovens, and the results were compared to determine whether the sequential processing of a mono-mode unit could provide for better lab logistics and pedagogy. Conditions were optimized so that yields matched in both types of…

  10. Pedagogical Comparison of Five Reactions Performed under Microwave Heating in Multi-Mode versus Mono-Mode Ovens: Diels-Alder Cycloaddition, Wittig Salt Formation, E2 Dehydrohalogenation to Form an Alkyne, Williamson Ether Synthesis, and Fischer Esterification

    ERIC Educational Resources Information Center

    Baar, Marsha R.; Gammerdinger, William; Leap, Jennifer; Morales, Erin; Shikora, Jonathan; Weber, Michael H.

    2014-01-01

    Five reactions were rate-accelerated relative to the standard reflux workup in both multi-mode and mono-mode microwave ovens, and the results were compared to determine whether the sequential processing of a mono-mode unit could provide for better lab logistics and pedagogy. Conditions were optimized so that yields matched in both types of…

  11. Orbital angular momentum in optical fibers

    NASA Astrophysics Data System (ADS)

    Bozinovic, Nenad

    Internet data traffic capacity is rapidly reaching limits imposed by nonlinear effects of single mode fibers currently used in optical communications. Having almost exhausted available degrees of freedom to orthogonally multiplex data in optical fibers, researchers are now exploring the possibility of using the spatial dimension of fibers, via multicore and multimode fibers, to address the forthcoming capacity crunch. While multicore fibers require complex manufacturing, conventional multi-mode fibers suffer from mode coupling, caused by random perturbations in fibers and modal (de)multiplexers. Methods that have been developed to address the problem of mode coupling so far, have been dependent on computationally intensive digital signal processing algorithms using adaptive optics feedback or complex multiple-input multiple-output algorithms. Here we study the possibility of using the orbital angular momentum (OAM), or helicity, of light, as a means of increasing capacity of future optical fiber communication links. We first introduce a class of specialty fibers designed to minimize mode coupling and show their potential for OAM mode generation in fibers using numerical analysis. We then experimentally confirm the existence of OAM states in these fibers using methods based on fiber gratings and spatial light modulators. In order to quantify the purity of created OAM states, we developed two methods based on mode-image analysis, showing purity of OAM states to be 90% after 1km in these fibers. Finally, in order to demonstrate data transmission using OAM states, we developed a 4-mode multiplexing and demultiplexing systems based on free-space optics and spatial light modulators. Using simple coherent detection methods, we successfully transmit data at 400Gbit/s using four OAM modes at a single wavelength, over 1.1 km of fiber. Furthermore, we achieve data transmission at 1.6Tbit/s using 10 wavelengths and two OAM modes. Our study indicates that OAM light can exist

  12. Coarse woody debris dynamics in two old-growth ecosystems

    SciTech Connect

    Harmon, M.E. ); Chen Hua )

    1991-10-01

    In this article, the dynamics of coarse woody debris are compound deciduous old-growth forest system Changbai Mountain Biosphere Reserve in China, and a coniferous old-growth forest system, H. J. Andrews Experimental Forest in Oregon. The objective is to compare in these two ecosystems the amount of coarse woody debris; the processes that affect coarse woody debris, such as tree mortality and decay rates; and the role of coarse woody debris in nutrient cycling. To assess importance in the global carbon budget, these two old-growth ecosystems are used to estimate the upper and lower limits of coarse woody debris mass for undisturbed temperate forests.

  13. Passive harmonic mode locking in a monolayer graphene-based long cavity fiber laser with high pulse energy

    NASA Astrophysics Data System (ADS)

    He, Xiaoying; Wang, D. N.

    2016-11-01

    Passive harmonic mode-locking fiber laser is experimentally demonstrated with high pulse energy and excellent signal-to-noise-ratio by employing monolayer graphene and multi-mode fiber. A repetition rate of 20.26 MHz corresponding to the 3rd harmonic mode-locking has been achieved, with a pulse duration of 603 fs, and a high single-pulse energy of 1.04 nJ. The spectral width of the pulses is found to be decreased with the increase of the harmonic order. Such a fiber laser is suitable for optical access network or material processing applications.

  14. Fiber webs

    Treesearch

    Roger M. Rowell; James S. Han; Von L. Byrd

    2005-01-01

    Wood fibers can be used to produce a wide variety of low-density three-dimensional webs, mats, and fiber-molded products. Short wood fibers blended with long fibers can be formed into flexible fiber mats, which can be made by physical entanglement, nonwoven needling, or thermoplastic fiber melt matrix technologies. The most common types of flexible mats are carded, air...

  15. Coarse mode aerosols in the High Arctic

    NASA Astrophysics Data System (ADS)

    Baibakov, K.; O'Neill, N. T.; Chaubey, J. P.; Saha, A.; Duck, T. J.; Eloranta, E. W.

    2014-12-01

    Fine mode (submicron) aerosols in the Arctic have received a fair amount of scientific attention in terms of smoke intrusions during the polar summer and Arctic haze pollution during the polar winter. Relatively little is known about coarse mode (supermicron) aerosols, notably dust, volcanic ash and sea salt. Asian dust is a regular springtime event whose optical and radiative forcing effects have been fairly well documented at the lower latitudes over North America but rarely reported for the Arctic. Volcanic ash, whose socio-economic importance has grown dramatically since the fear of its effects on aircraft engines resulted in the virtual shutdown of European civil aviation in the spring of 2010 has rarely been reported in the Arctic in spite of the likely probability that ash from Iceland and the Aleutian Islands makes its way into the Arctic and possibly the high Arctic. Little is known about Arctic sea salt aerosols and we are not aware of any literature on the optical measurement of these aerosols. In this work we present preliminary results of the combined sunphotometry-lidar analysis at two High Arctic stations in North America: PEARL (80°N, 86°W) for 2007-2011 and Barrow (71°N,156°W) for 2011-2014. The multi-years datasets were analyzed to single out potential coarse mode incursions and study their optical characteristics. In particular, CIMEL sunphotometers provided coarse mode optical depths as well as information on particle size and refractive index. Lidar measurements from High Spectral Resolution lidars (AHSRL at PEARL and NSHSRL at Barrow) yielded vertically resolved aerosol profiles and gave an indication of particle shape and size from the depolarization ratio and color ratio profiles. Additionally, we employed supplementary analyses of HYSPLIT backtrajectories, OMI aerosol index, and NAAPS (Navy Aerosol Analysis and Prediction System) outputs to study the spatial context of given events.

  16. The design of analysis system of refractive index profile of optical fiber

    NASA Astrophysics Data System (ADS)

    He, Gao; Liu, Zhihai

    2011-11-01

    This paper developed an intelligent optical fiber refractive index profile measurement system. This system is based on the principle of the refracted near-field measurement. The whole system is the use of a unique high-resolution non-contact capacitive displacement sensor to monitor the scanning position of the fiber measured. At the same time we used a shading screen which was embedded into the sample pool. Using this method, we can totally save space. Finally, we used a high curvature condenser to collection of reflected light which we used a photo detector to collect. The collected signal was brought into the computer to calculate the optical fiber refractive index. The whole system is totally enclosed operating instrument with an easy-to-use software interface for performing measurements of both multi mode and single mode optical fiber, which can easy pick up the signal automatically and processing in computer. Measurement accuracy can reach 10-4. It is fit for measuring the refractive index of single-mode fibers and multi-mode fibers.

  17. A Coarse Pointing Assembly for Optical Communication

    NASA Technical Reports Server (NTRS)

    Szekely, G.; Blum, D.; Humphries, M.; Koller, A.; Mussett, D.; Schuler, S.; Vogt, P.

    2010-01-01

    In the framework of a contract with the European Space Agency, RUAG Space are developing a Coarse Pointing Assembly for an Optical Communication Terminal with the goal to enable high-bandwidth data exchange between GEO and/or LEO satellites as well as to earth-bound ground stations. This paper describes some development and testing aspects of such a high precision opto-mechanical device, with emphasis on the influence of requirements on the final design, the usage of a Bearing Active Preload System, some of the lessons learned on the BAPS implementation, the selection of a flex print design as rotary harness and some aspects of functional and environmental testing.

  18. Thermo-optical effects in high-power ytterbium-doped fiber amplifiers.

    PubMed

    Hansen, Kristian Rymann; Alkeskjold, Thomas Tanggaard; Broeng, Jes; Lægsgaard, Jesper

    2011-11-21

    We investigate the effect of temperature gradients in high-power Yb-doped fiber amplifiers by a numerical beam propagation model, which takes thermal effects into account in a self-consistent way. The thermally induced change in the refractive index of the fiber leads to a thermal lensing effect, which decreases the effective mode area. Furthermore, it is demonstrated that the thermal lensing effect may lead to effective multi-mode behavior, even in single-mode designs, which could possibly lead to degradation of the output beam quality.

  19. An Ultra-fast Fiber Optic Pressure Sensor for Blast Event Measurements

    DTIC Science & Technology

    2012-01-01

    sensor consists of three parts: a SMF, a MMF and a silicon dioxide diaphragm. The FP cavity is fabricated by wet etching away the core of the MMF . The...consists of three parts: a single-mode fiber (SMF), a multi-mode fiber ( MMF ) and a silicon dioxide diaphragm with controllable thickness. The SMF is...used for propagating the light and illuminating the MMF with the diaphragm. An FP cavity is fabricated along the axis of the MMF by wet etching away the

  20. Pd/V{2}O{5} fiber optic hydrogen gas sensor*

    NASA Astrophysics Data System (ADS)

    Maciak, E.; Opilski, Z.; Urbańczyk, M.

    2005-10-01

    The paper presents an optical-fiber hydrogen sensor. The sensor utilizes a layered sensing structure. This structure is a layered Fabry-Perot interferometer and includes gasochromic vanadium pentoxide (V{2}O{5}). A structure is made at the end of multi-mode optical fiber as a sensing element. The sensor permits to detect and to measure the concentration of hydrogen in a gaseous medium. The optical H{2} gas sensor has a very short response time and a fast regeneration time at room temperature.

  1. Optical hydrogen sensitivity of Pd-metal oxide composite films prepared on fiber optics

    NASA Astrophysics Data System (ADS)

    Maciak, Erwin; Opilski, Zbigniew; Urbanczyk, Marian

    2005-09-01

    The paper presents an optical-fiber hydrogen sensor. The sensor utilises a layered Fabry-Perot interferometer and includes gasochromic metal oxides (V2O5, Nb2O5, CeO2). The structure contains at the end a multi-mode optical fiber as the sensing element. The sensor permits to detect and to measure the concentration of hydrogen in a gaseous medium. A comparison of the properties of selected gasochromic metal oxides in the interferometric sensor structures has been presented.

  2. A family of fiber-optic based pressure sensors for intracochlear measurements

    NASA Astrophysics Data System (ADS)

    Olson, Elizabeth S.; Nakajima, Hideko H.

    2015-02-01

    Fiber-optic pressure sensors have been developed for measurements of intracochlear pressure. The present family of transducers includes an 81 μm diameter sensor employing a SLED light source and single-mode optic fiber, and LED/multi-mode sensors with 126 and 202 μm diameter. The 126 μm diameter pressure sensor also has been constructed with an electrode adhered to its side, for coincident pressure and voltage measurements. These sensors have been used for quantifying cochlear mechanical impedances, informing our understanding of conductive hearing loss and its remediation, and probing the operation of the cochlear amplifier.

  3. Fabrication of optical waveguide structures based on PDMS using photoresist fibers

    NASA Astrophysics Data System (ADS)

    Gaso, Peter; Pudiš, Dusan; Martincek, Ivan; Jandura, Daniel

    2014-12-01

    We describe fabrication process of optical waveguide structures such as multi-mode optical splitter and optical waveguide with surface Bragg grating in polydimethylsiloxane (PDMS). Technology based on drawing of thin photoresist fiber with diameter up to 100 μm was developed and optimized. In this way, fibers drawn from photoresist form cores of waveguides in PDMS slab. After removal of the photoresist, created air channels can be filled in with different liquids. We prepared multimode waveguide structures in PDMS composed of two PDMS materials with different refractive indices. Using this technology, also complicated waveguide structures were prepared as optical splitter and surface Bragg grating were prepared in PDMS material.

  4. Early deterioration of coarse woody debris.

    SciTech Connect

    Tainter, Frank, H.; McMinn, James, W.

    1999-02-16

    Tainter, F.H., and J.W. McMinn. 1999. Early deterioration of coarse woody debris. In: Proc. Tenth Bien. South. Silv. Res. Conf. Shreveport, LA, February 16-18, 1999. Pp. 232-237 Abstract - Coarse woody debris (CWD) is an important structural component of southern forest ecosystems. CWD loading may be affected by different decomposition rates on sites of varying quality. Bolts of red oak and loblolly pine were placed on plots at each of three (hydric, mesic. and xerlc) sites at the Savannah River Site and sampled over a I6-week period. Major changes were in moisture content and nonstructural carbohydrate content (total carbohydrates, reducing sugars, and starch) of sapwood. Early changes in nonstructural carbohydrate levels following placement of the bolts were likely due to reallocation of these materials by sapwood parenchyma cells. These carbohydrates later formed pools increasingly metabolized by bacteria and invading fungi. Most prevalent fungi in sapwood were Ceratocysfis spp. in pine and Hypoxy/on spp. in oak. Although pine sapwood became blue stained and oak sapwood exhibited yellow soft decay with black zone lines, estimators of decay (specific gravity, sodium hydroxide solubility, and holocellulose content) were unchanged during the 16-week study period. A small effect of site was detected for starch content of sapwood of both species. Fungal biomass in sapwood of both species, as measured by ergosterol content, was detectable at week zero, increased somewhat by week three and increased significantly by week 16.

  5. Multi-mode technique for the determination of the biaxial Y{sub 2}SiO{sub 5} permittivity tensor from 300 to 6 K

    SciTech Connect

    Carvalho, N. C. Le Floch, J-M.; Tobar, M. E.; Krupka, J.

    2015-05-11

    The Y{sub 2}SiO{sub 5} (YSO) crystal is a dielectric material with biaxial anisotropy with known values of refractive index at optical frequencies. It is a well-known rare-earth (RE) host material for optical research and more recently has shown promising performance for quantum-engineered devices. In this paper, we report the first microwave characterization of the real permittivity tensor of a bulk YSO sample, as well as an investigation of the temperature dependence of the tensor components from 296 K down to 6 K. Estimated uncertainties were below 0.26%, limited by the precision of machining the cylindrical dielectric. Also, the electrical Q-factors of a few electromagnetic modes were recorded as a way to provide some information about the crystal losses over the temperature range. To solve the tensor components necessary for a biaxial crystal, we developed the multi-mode technique, which uses simultaneous measurement of low order whispering gallery modes. Knowledge of the permittivity tensor offers important data, essential for the design of technologies involving YSO, such as microwave coupling to electron and hyperfine transitions in RE doped samples at low temperatures.

  6. Multi-mode technique for the determination of the biaxial Y2SiO5 permittivity tensor from 300 to 6 K

    NASA Astrophysics Data System (ADS)

    Carvalho, N. C.; Le Floch, J.-M.; Krupka, J.; Tobar, M. E.

    2015-05-01

    The Y2SiO5 (YSO) crystal is a dielectric material with biaxial anisotropy with known values of refractive index at optical frequencies. It is a well-known rare-earth (RE) host material for optical research and more recently has shown promising performance for quantum-engineered devices. In this paper, we report the first microwave characterization of the real permittivity tensor of a bulk YSO sample, as well as an investigation of the temperature dependence of the tensor components from 296 K down to 6 K. Estimated uncertainties were below 0.26%, limited by the precision of machining the cylindrical dielectric. Also, the electrical Q-factors of a few electromagnetic modes were recorded as a way to provide some information about the crystal losses over the temperature range. To solve the tensor components necessary for a biaxial crystal, we developed the multi-mode technique, which uses simultaneous measurement of low order whispering gallery modes. Knowledge of the permittivity tensor offers important data, essential for the design of technologies involving YSO, such as microwave coupling to electron and hyperfine transitions in RE doped samples at low temperatures.

  7. Three dimensional hydrodynamic calculations with adaptive mesh refinement of the evolution of Rayleigh Taylor and Richtmyer Meshkov instabilities in converging geometry: Multi-mode perturbations

    SciTech Connect

    Klein, R.I. |; Bell, J.; Pember, R.; Kelleher, T.

    1993-04-01

    The authors present results for high resolution hydrodynamic calculations of the growth and development of instabilities in shock driven imploding spherical geometries in both 2D and 3D. They solve the Eulerian equations of hydrodynamics with a high order Godunov approach using local adaptive mesh refinement to study the temporal and spatial development of the turbulent mixing layer resulting from both Richtmyer Meshkov and Rayleigh Taylor instabilities. The use of a high resolution Eulerian discretization with adaptive mesh refinement permits them to study the detailed three-dimensional growth of multi-mode perturbations far into the non-linear regime for converging geometries. They discuss convergence properties of the simulations by calculating global properties of the flow. They discuss the time evolution of the turbulent mixing layer and compare its development to a simple theory for a turbulent mix model in spherical geometry based on Plesset`s equation. Their 3D calculations show that the constant found in the planar incompressible experiments of Read and Young`s may not be universal for converging compressible flow. They show the 3D time trace of transitional onset to a mixing state using the temporal evolution of volume rendered imaging. Their preliminary results suggest that the turbulent mixing layer loses memory of its initial perturbations for classical Richtmyer Meshkov and Rayleigh Taylor instabilities in spherically imploding shells. They discuss the time evolution of mixed volume fraction and the role of vorticity in converging 3D flows in enhancing the growth of a turbulent mixing layer.

  8. Multi-mode acquisition (MMA): An MS/MS acquisition strategy for maximizing selectivity, specificity and sensitivity of DIA product ion spectra.

    PubMed

    Williams, Brad J; Ciavarini, Steve J; Devlin, Curt; Cohn, Steven M; Xie, Rong; Vissers, Johannes P C; Martin, LeRoy B; Caswell, Allen; Langridge, James I; Geromanos, Scott J

    2016-08-01

    In proteomics studies, it is generally accepted that depth of coverage and dynamic range is limited in data-directed acquisitions. The serial nature of the method limits both sensitivity and the number of precursor ions that can be sampled. To that end, a number of data-independent acquisition (DIA) strategies have been introduced with these methods, for the most part, immune to the sampling issue; nevertheless, some do have other limitations with respect to sensitivity. The major limitation with DIA approaches is interference, i.e., MS/MS spectra are highly chimeric and often incapable of being identified using conventional database search engines. Utilizing each available dimension of separation prior to ion detection, we present a new multi-mode acquisition (MMA) strategy multiplexing both narrowband and wideband DIA acquisitions in a single analytical workflow. The iterative nature of the MMA workflow limits the adverse effects of interference with minimal loss in sensitivity. Qualitative identification can be performed by selected ion chromatograms or conventional database search strategies.

  9. Stabilized and tunable single-longitudinal-mode erbium fiber laser employing ytterbium-doped fiber based interference filter

    NASA Astrophysics Data System (ADS)

    Yeh, Chien-Hung; Tsai, Ning; Zhuang, Yuan-Hong; Chow, Chi-Wai; Chen, Jing-Heng

    2017-02-01

    In this demonstration, to achieve stabilized and wavelength-selectable single-longitudinal-mode (SLM) erbium-doped fiber (EDF) laser, a short length of ytterbium-doped fiber (YDF) is utilized to serve as a spatial multi-mode interference (MMI) inside a fiber cavity for suppressing multi-longitudinal-mode (MLM) significantly. In the measurement, the output powers and optical signal to noise ratios (OSNRs) of proposed EDF ring laser are measured between -9.85 and -5.71 dBm; and 38.03 and 47.95 dB, respectively, in the tuning range of 1530.0-1560.0 nm. In addition, the output SLM and stability performance are also analyzed and discussed experimentally.

  10. Recirculating sprayer for fiber-filled paints

    NASA Technical Reports Server (NTRS)

    Major, R. K.

    1980-01-01

    Recirculating paint sprayer applies spray of coarse filler in highly volatile solvent. Sprayer was developed for applying insulation material containing epxoy resin, glass fibers, and inert fillers suspended in chlorinated solvents. Sprayer resists abrasive action of fiberglass filler and chemical activity of solvent. Pump and position ensure more uniform pressure at spray gun without backpressure regulator, which tended to clog in old sprayer.

  11. FOCEX: A fiber-optic extender for a high speed parallel RS485 data cable

    NASA Astrophysics Data System (ADS)

    Meadows, J. T.; Anderson, J. T.; Cooper, P. S.; Engelfried, J.; Franzen, J. W.; Forster, B. G.; Levinson, F.; Rawls, J.; Haber, S.

    1995-05-01

    For longer-distant, high speed data links, optical fiber becomes most cost-effective than copper or other hard wire cable systems. Fermilab supplied to Finisar Corp. of Menlo Park, CA, a set of specifications for card functions, sizes and interconnector pin assignments. Finisar designed and assembled a set of fiber optical P.C. cards using 100 megabyte/sec commercial optoelectronics and a serialization and deserialization HOT-ROD chipset designed by GAZELLE Microcircuits, Inc. (A Tri Quint Semiconductors company). The cooperative effort between Fermilab and Finisar has allowed Fermilab to created a reliable 50 Megabytes/sec (40 bit parallel RS485 DART data bus) cable to cable extender using a virtually invisible Fiber Channel point-to-point(FC-0) fiber optical single-simplex system. The system is easily capable of sustaining a 50 megabytes/sec of data, control and status line throughput at distances of 1625 feet (500 meters) using standard multi-mode fiber.

  12. Natural fibers

    Treesearch

    Craig M. Clemons; Daniel F. Caulfield

    2005-01-01

    The term “natural fibers” covers a broad range of vegetable, animal, and mineral fibers. However, in the composites industry, it usually refers to wood fiber and agrobased bast, leaf, seed, and stem fibers. These fibers often contribute greatly to the structural performance of the plant and, when used in plastic composites, can provide significant reinforcement. Below...

  13. Fiber diffraction without fibers.

    PubMed

    Poon, H-C; Schwander, P; Uddin, M; Saldin, D K

    2013-06-28

    Postprocessing of diffraction patterns of completely randomly oriented helical particles, as measured, for example, in so-called "diffract-and-destroy" experiments with an x-ray free electron laser can yield "fiber diffraction" patterns expected of fibrous bundles of the particles. This will allow "single-axis alignment" to be performed computationally, thus obviating the need to do this by experimental means such as forming fibers and laser or flow alignment. The structure of such particles may then be found by either iterative phasing methods or standard methods of fiber diffraction.

  14. Freezing promotes perception of coarse visual features.

    PubMed

    Lojowska, Maria; Gladwin, Thomas E; Hermans, Erno J; Roelofs, Karin

    2015-12-01

    Freezing is an evolutionarily preserved defensive behavior, characterized by immobility and heart rate deceleration, which is thought to promote visual perception. Rapid perceptual assessment of threat is crucial in life-threatening situations; for example, when policemen need to make split-second decisions about the use of deadly force. Here, we hypothesized that freezing is specifically associated with better perception of rapidly processed coarse, low-spatial frequency (LSF) features. We used a visual discrimination task in which participants determined the orientation of LSF and high-spatial frequency (HSF) gratings under threat of shock and safe conditions. As predicted, threat anticipation improved perception of LSF at the expense of HSF gratings. Crucially, stronger decrease in heart rate, a parasympathetic physiological index of freezing, was linked to better perception of LSF. These results provide empirical evidence for the comobilization of physiological and perceptual processes, which may play an important role in decision making under acute stress. (c) 2015 APA, all rights reserved).

  15. Coarse-graining approach to quantum cosmology

    NASA Astrophysics Data System (ADS)

    Calzetta, Esteban; Castagnino, Mario; Scoccimarro, Román

    1992-04-01

    We consider a Friedmann-Robertson-Walker model with both classical radiation and a massive (conformally coupled) quantum scalar field in the framework of quantum cosmology. We define a density matrix and introduce a notion of ``relevance'' which splits this density matrix into a ``relevant'' and an ``irrelevant'' part. A ``generalized coarse-graining method'' is used to obtain the evolution (in Robertson-Walker a ``time'') of the relevant density matrix, taking into account the back reaction of the irrelevant variables. We discuss the physical basis for the choice of a concept of relevance, and the features of cosmic evolution brought forward by the effective dynamics. In the limit of ``small universes,'' the relevant subdynamics is dissipative.

  16. Coarse-grained model of glycosaminoglycans.

    PubMed

    Samsonov, Sergey A; Bichmann, Leon; Pisabarro, M Teresa

    2015-01-26

    Glycosaminoglycans (GAGs) represent a class of anionic periodic linear polysaccharides, which mediate cell communication processes by interactions with their protein targets in the extracellular matrix. Due to their high flexibility, charged nature, periodicity, and polymeric nature, GAGs are challenging systems for computational approaches. To deal with the length challenge, coarse-grained (CG) modeling could be a promising approach. In this work, we develop AMBER-compatible CG parameters for GAGs using all-atomic (AA) molecular dynamics (MD) simulations in explicit solvent and the Boltzmann conversion approach. We compare both global and local properties of GAGs obtained in the simulations with AA and CG approaches, and we conclude that our CG model is appropriate for the MD approach of long GAG molecules at long time scales.

  17. Structure-based coarse-graining in liquid slabs.

    PubMed

    Jochum, Mara; Andrienko, Denis; Kremer, Kurt; Peter, Christine

    2012-08-14

    Structure-based coarse-graining relies on matching the pair correlation functions of a reference (atomistic) and a coarse-grained system. As such, it is designed for systems with uniform density distributions. Here, we demonstrate how it can be generalized for inhomogeneous systems by coarse-graining slabs of liquid water and methanol in vacuum, as well as a single benzene molecule at the water-vacuum interface. Our conclusion is that coarse-graining performed in inhomogeneous systems improves thermodynamic properties and the structure of interfaces without significant alterations to the local structure of the bulk liquid.

  18. In-fiber modal interferometer based on dual-concentric-core photonic crystal fiber and its strain, temperature and refractive index characteristics

    NASA Astrophysics Data System (ADS)

    Chen, Weiguo; Lou, Shuqin; Wang, Liwen; Feng, Suchun; zou, Hui; Lu, Wenliang; Jian, Shuisheng

    2011-06-01

    An in-fiber modal interferometer is demonstrated by splicing a section of homemade dual-concentric-core photonic crystal fiber (DCCPCF) and two segments of single-mode fibers (SMFs) with collapsing the air holes in the splice regions. By analyzing the transmission spectra and the spatial frequency spectra of the interferometers, it's observed that the main interfering modes are the high-order ring modes, which are different from the previously reported interferometers using the single-, few- or multi-mode fibers. The influences of the lengths of DCCPCF and the first collapsed region on the interferometers were investigated experimentally. The strain, temperature and refractive index characteristics of the interferometer were analyzed.

  19. Microstructural evolution of carbon nanotube fibers: deformation and strength mechanism.

    PubMed

    Liu, Xia; Lu, Weibang; Ayala, Orlando M; Wang, Lian-Ping; Karlsson, Anette M; Yang, Qingsheng; Chou, Tsu-Wei

    2013-03-07

    A comprehensive investigation of the mechanical behavior and microstructural evolution of carbon nanotube (CNT) continuous fibers under twisting and tension is conducted using coarse-grained molecular dynamics simulations. The tensile strength of CNT fibers with random CNT stacking is found to be higher than that of fibers with regular CNT stacking. The factor dominating the mechanical response of CNT fibers is identified as individual CNT stretching. A simplified twisted CNT fiber model is studied to illustrate the structural evolution mechanisms of CNT fibers under tension. Moreover, it is demonstrated that CNT fibers can be reinforced by enhancing intertube interactions. This study would be helpful not only in the general understanding of the nano- and micro-scale factors affecting CNT fibers' mechanical behavior, but also in the optimal design of CNT fibers' architecture and performance.

  20. Ultra-trace level analysis of morpholine, cyclohexylamine, and diethylaminoethanol in steam condensate by gas chromatography with multi-mode inlet, and flame ionization detection.

    PubMed

    Luong, J; Shellie, R A; Cortes, H; Gras, R; Hayward, T

    2012-03-16

    Steam condensate water treatment is a vital and integral part of the overall cooling water treatment process. Steam condensate often contains varying levels of carbon dioxide and oxygen which acts as an oxidizer. Carbon dioxide forms corrosive carbonic acid when dissolved in condensed steam. To neutralize the harmful effect of the carbonic acid, volatile amine compounds such as morpholine, cyclohexylamine, and diethylaminoethanol are often employed as part of a strategy to control corrosion in the water treatment process. Due to the high stability of these compounds in a water matrix, the indirect addition of such chemicals into the process via steam condensate often results in their presence throughout the process and even into the final product. It is therefore important to understand the impact of these chemicals and their fate within a chemical plant. The ability to analyze such compounds by gas chromatography has historically been difficult due to the lack of chromatographic system inertness at the trace level concentrations especially in an aqueous matrix. Here a highly sensitive, practical, and reliable gas chromatographic approach is described for the determination of morpholine, cyclohexylamine, and diethylaminoethanol in steam condensate at the part-per-billion (ppb) levels. The approach does not require any sample enrichment or derivatization. The technique employs a multi-mode inlet operating in pulsed splitless mode with programmed inlet temperature for sample introduction, an inert base-deactivated capillary column for solute separation and flame ionization detection. Chromatographic performance was further enhanced by the incorporation of 2-propanol as a co-solvent. Detection limits for morpholine, cyclohexylamine, diethylaminoethanol were established to be 100 ppb (v/v), with relative standard deviations (RSD) of less than 6% at the 95% confidence level (n=20) and a percent recovery of 96% or higher for the solutes of interest over a range of 0

  1. Catastrophic optical bulk degradation (COBD) in high-power single- and multi-mode InGaAs-AlGaAs strained quantum well lasers

    NASA Astrophysics Data System (ADS)

    Sin, Yongkun; Lingley, Zachary; Brodie, Miles; Presser, Nathan; Moss, Steven C.

    2017-02-01

    High-power single-mode (SM) and multi-mode (MM) InGaAs-AlGaAs strained quantum well (QW) lasers are critical components for both telecommunications and space satellite communications systems. However, little has been reported on failure modes and degradation mechanisms of high-power SM and MM InGaAs-AlGaAs strained QW lasers although it is crucial to understand failure modes and underlying degradation mechanisms in developing these lasers that meet lifetime requirements for space satellite systems, where extremely high reliability of these lasers is required. Our present study addresses the aforementioned issues by performing long-term life-tests followed by failure mode analysis (FMA) and physics of failure investigation. We performed long-term accelerated life-tests on state-of-the-art SM and MM InGaAs-AlGaAs strained QW lasers under ACC (automatic current control) mode. Our life-tests have accumulated over 25,000 test hours for SM lasers and over 35,000 test hours for MM lasers. FMA was performed on failed SM lasers using electron beam induced current (EBIC). This technique allowed us to identify failure types by observing dark line defects. All the SM failures we studied showed catastrophic and sudden degradation and all of these failures were bulk failures. Our group previously reported that bulk failure or COBD (catastrophic optical bulk damage) is the dominant failure mode of MM InGaAs-AlGaAs strained QW lasers. Since degradation mechanisms responsible for COBD are still not well understood, we also employed other techniques including focused ion beam (FIB) processing and high-resolution TEM to further study dark line defects and dislocations in post-aged lasers. Our long-term life-test results and FMA results are reported.

  2. Failure mode analysis of degraded InGaAs-AlGaAs strained quantum well multi-mode vertical-cavity surface-emitting lasers

    NASA Astrophysics Data System (ADS)

    Sin, Yongkun; Lingley, Zachary; Brodie, Miles; Huang, Michael; Bushmaker, Adam; Theiss, Jesse; Presser, Nathan; Foran, Brendan; Moss, Steven C.

    2016-03-01

    Remarkable progress made in vertical cavity surface emitting lasers (VCSELs) emitting at 850 and 980 nm has led them to find an increasing number of applications in high speed data communications as well as in potential space satellite systems. However, little has been reported on reliability and failure modes of InGaAs VCSELs emitting at ~980 nm although it is crucial to understand failure modes and underlying degradation mechanisms in developing these VCSELs that exceed lifetime requirements for space missions. The active layer of commercial VCSELs that we studied consisted of two or three InGaAs quantum wells. The laser structures were fabricated into deep mesas followed by a steam oxidation process to form oxide-apertures for current and optical confinements. Our multi- mode VCSELs showed a laser threshold of ~ 0.5 mA at RT. Failures were generated via accelerated life-testing of VCSELs. For the present study, we report on failure mode analysis of degraded oxide-VCSELs using various techniques. We employed nondestructive techniques including electroluminescence (EL), optical beam induced current (OBIC), and electron beam induced current (EBIC) techniques as well as destructive techniques including focused ion beam (FIB) and high-resolution TEM techniques to study VCSELs that showed different degradation behaviors. Especially, we employed FIB systems to locally remove a portion of top-DBR mirrors of degraded VCSELs, which made it possible for our subsequent EBIC and OBIC techniques to locate damaged areas that were generated as a result of degradation processes and also for our HR-TEM technique to prepare TEM cross sections from damaged areas. Our nondestructive and destructive physical analysis results are reported including defect and structural analysis results from pre-aged VCSELs as well as from degraded VCSELs life-tested under different test conditions.

  3. Rigorous Treatment of Multi-species Multi-mode Ligand-Receptor Interactions in 3D-QSAR: CoMFA Analysis of Thyroxine Analogs Binding to Transthyretin

    PubMed Central

    Natesan, Senthil; Wang, Tiansheng; Lukacova, Viera; Bartus, Vladimir; Khandelwal, Akash; Balaz, Stefan

    2011-01-01

    For a rigorous analysis of the receptor-ligand binding, speciation of the ligands caused by ionization, tautomerism, covalent hydration, and dynamic stereoisomerism needs to be considered. Each species may bind in several orientations or conformations (modes), especially for flexible ligands and receptors. A thermodynamic description of the multi-species (MS), multi-mode (MM) binding events shows that the overall association constant is equal to the weighted sum of the sums of microscopic association constants of individual modes for each species, with the weights given by the unbound fractions of individual species. This expression is a prerequisite for a precise quantitative characterization of the ligand-receptor interactions in both structure-based and ligand-based structure-activity analyses. We have implemented the MS-MM correlation expression into the Comparative Molecular Field Analysis (CoMFA), which deduces a map of the binding site from structures and binding affinities of a ligand set, in the absence of experimental structural information on the receptor. The MS-MM CoMFA approach was applied to published data for binding to transthyretin of 28 thyroxine analogs, each forming up to four ionization species under physiological conditions. The published X-ray structures of several analogs, exhibiting multiple binding modes, served as templates for the MS-MM superposition of thyroxine analogs. Additional modes were generated for compounds with flexible alkyl substituents, to identify bound conformations. The results demonstrate that the MS-MM modification improved predictive abilities of the CoMFA models, even for the standard procedure with MS-MM selected species and modes. The predicted prevalences of individual modes and the generated receptor site model are in reasonable agreement with the available X-ray data. The calibrated model can help in the design of inhibitors of transthyretin amyloid fibril formation. PMID:21476521

  4. Coarse-graining with information theory and the relative entropy

    NASA Astrophysics Data System (ADS)

    Shell, M. Scott

    2013-03-01

    There remain many both fundamental and practical/methodological questions regarding how coarse-grained models should be developed. Are there theoretically intuitive and numerically robust strategies for turning small-scale all-atom simulations into coarse models suitable for large-scale modeling? How can we identify what atomic details are unnecessary and can be discarded? Are there systematic ways to detect emergent physics? Here we discuss a fundamentally new approach to this problem. We propose that a natural way of viewing the coarse-graining problem is in terms of information theory. A quantity called the relative entropy measures the information lost upon coarse graining and hence the (inverse) fitness of a particular coarse-grained model. Minimization of the relative entropy thus provides a sort-of universal variational principle for coarse-graining, and a way to ``automatically'' discover and generate coarse models of many systems. We show that this new approach enables us to develop very simple but surprisingly accurate models of water, hydrophobic interactions, self-assembling peptides, and proteins that enable new physical insights as well as simulations of large-scale interactions. We discuss both theoretical and numerical aspects of this approach, in particular highlighting a new coarse-graining algorithm that efficiently optimizes coarse-grained models with even thousands of free parameters. We also discuss how the relative entropy approach suggests novel strategies for predicting the errors of coarse models, for identifying relevant degrees of freedom to retain, and for understanding the relationships among other coarse-graining methodologies.

  5. Pretreatment of turkey fat-containing wastewater in coarse sand and gravel/coarse sand bioreactors.

    PubMed

    Gaur, Rashmi Singh; Cai, Ling; Tuovinen, Olli H; Mancl, Karen M

    2010-02-01

    Fat, oil and grease in wastewater can be difficult to treat because of their slow decomposition. Traditional pretreatment facilities to remove fat, oil and grease from wastewater are increasingly costly. The hypothesis in this study was that pretreatment of animal fat-containing wastewater in sand and sand/gravel filters facilitates the conversion of slowly degradable organic matter measured as the difference between chemical oxygen demand (COD) and 5-day biochemical oxygen demand (BOD(5)) for subsequent biological treatment. The pretreatment was evaluated using simulated turkey-processing wastewater and coarse sand and sand/gravel filters at a constant hydraulic loading rate of 132L/m(2)/day. Two types of fixed media reactors were employed: (i) one set with a varying depth of coarse sand, and (ii) the second was similar but with an additional pea gravel cap. The results indicated that the relative removal of COD was slightly improved in the sand bioreactors with a pea gravel cap irrespective of the depth of coarse sand, but partial conversion to BOD(5) was not consistently demonstrated. Pea gravel may act as a sieve to entrap organic matter including fat globules from the wastewater. Multiple dosing at the same daily loading rate slightly improved the treatment efficiency of the sand bioreactors. The ratios of influent-COD/effluent-COD were always greater than 1.0 following a change in the dosing frequency after a rest period, suggesting that organic matter, specifically fat globules in this case, was retained by the column matrix.

  6. Temperature insensitive one-dimensional bending vector sensor based on eccentric-core fiber and air cavity Fabry-Perot interferometer

    NASA Astrophysics Data System (ADS)

    Kong, Jing; Zhou, Ai; Yuan, Libo

    2017-04-01

    A temperature insensitive directional bending sensor based on an eccentric-core fiber (ECF) cascaded with an air-cavity Fabry–Perot (F-P) interferometer is presented and demonstrated. The ECF-based air cavity F-P interferometer is fabricated by fuse splicing a piece of hollow-core fiber (HCF) in between an ECF and a multi-mode fiber (MMF). The bending sensitivities of the sensor at the two opposite most sensitive directions are 79.5 pm/m‑1 and ‑81.5 pm/m‑1, respectively. The temperature sensitivity of the proposed structure is as low as 1 pm °C‑1.

  7. Breaking the glass ceiling: hollow OmniGuide fibers

    NASA Astrophysics Data System (ADS)

    Johnson, Steven G.; Ibanescu, Mihai; Skorobogatiy, Maksim A.; Weisberg, Ori; Engeness, Torkel D.; Soljacic, Marin; Jacobs, Steven A.; Joannopoulos, John D.; Fink, Yoel

    2002-04-01

    We argue that OmniGuide fibers, which guide light within a hollow core by concentric multilayer films having the property of omnidirectional reflection, have the potential to lift several physical limitations of silica fibers. We show how the strong confinement in OmniGuide fibers greatly suppresses the properties of the cladding materials: even if highly lossy and nonlinear materials are employed, both the intrinsic losses and nonlinearities of silica fibers can be surpassed by orders of magnitude. This feat, impossible to duplicate in an index-guided fiber with existing materials, would open up new regimes for long-distance propagation and dense wavelength-division multiplexing (DWDM). The OmniGuide-fiber modes bear a strong analogy to those of hollow metallic waveguides; from this analogy, we are able to derive several general scaling laws with core radius. Moreover, there is strong loss discrimination between guided modes, depending upon their degree of confinement in the hollow core: this allows large, ostensibly multi-mode cores to be used, with the lowest-loss TE01 mode propagating in an effectively single-mode fashion. Finally, because this TE01 mode is a cylindrically symmetrical ('azimuthally' polarized) singlet state, it is immune to polarization-mode dispersion (PMD), unlike the doubly-degenerate linearly-polarized modes in silica fibers that are vulnerable to birefringence.

  8. A vertical coarse approach scanning tunneling microscope

    NASA Astrophysics Data System (ADS)

    Drevniok, Benedict

    A Pan-style scanning tunneling microscope (STM), with a vertical coarse approach mechanism, was designed, built and tested. The microscope will be operated in ultra-high vacuum and also at cryogenic temperatures (8 K) inside a continuous flow cryostat. Fundamental differences in operating principle exist between the new microscope and the beetle-type inertial sliders [1] that have been the mainstay of the group for the last eight years. While Pan-style microscopes do already exist [2], they remain challenging to build, and an active area of research [3]. This system represents a bold departure from well-trodden paths, and will greatly expand the range of experiments that our group can perform. The operating principles of inertial piezoelectric motors are detailed. Design guidelines for a piezoelectric motor are given, and used in the design of the vertical coarse approach motor. A simple, inexpensive implementation for creating waveforms with an extremely fast fall time is discussed. Motor performance is tested, and a minimum step size of 20nm is found for frequencies ranging from 0 Hz to 3 kHz. The motor operates with high dynamic range: individual 20nm steps can be taken, as well as being able to move at a velocity of 0.4mm s-1. Little is known about the vibrational properties of Pan-style microscopes. Vibrational testing of the microscope revealed the expected scanner bending mode at 1.6 kHz (above the scanner bending mode of our beetles at 1.2 kHz), and a complicated response signal above this frequency. Custom extension springs for an eddy-current damping system are built and tested. A low resonant frequency of 1.8 Hz is found, which is ideal for the application. Initial testing of the STM in ambient conditions is performed on two different surfaces. A moire supermesh [4] with periodicity 3nm is observed on a highly-oriented pyrolytic graphite (HOPG) surface, and agrees well with previously published results. Using a flame-annealed Gold on mica surface, a low

  9. FINE AND COARSE PARTICLES: CONCENTRATION RELATIONSHIPS RELEVANT TO EPIDEMIOLOGICAL STUDIES

    EPA Science Inventory

    Fine particles and coarse particles are defined in terms of the modal structure of particle size distributions typically observed in the atmosphere. Differences among the various modes are discussed. The fractions of fine and coarse particles collected in specific size ranges, ...

  10. FINE AND COARSE PARTICLES: CONCENTRATION RELATIONSHIPS RELEVANT TO EPIDEMIOLOGICAL STUDIES

    EPA Science Inventory

    Fine particles and coarse particles are defined in terms of the modal structure of particle size distributions typically observed in the atmosphere. Differences among the various modes are discussed. The fractions of fine and coarse particles collected in specific size ranges, ...

  11. Coarse-grained models for biological simulations

    NASA Astrophysics Data System (ADS)

    Wu, Zhe; Cui, Qiang; Yethiraj, Arun

    2011-03-01

    The large timescales and length-scales of interest in biophysics preclude atomistic study of many systems and processes. One appealing approach is to use coarse-grained (CG) models where several atoms are grouped into a single CG site. In this work we describe a new CG force field for lipids, surfactants, and amino acids. The topology of CG sites is the same as in the MARTINI force field, but the new model is compatible with a recently developed CG electrostatic water (Big Multiple Water, BMW) model. The model not only gives correct structural, elastic properties and phase behavior for lipid and surfactants, but also reproduces electrostatic properties at water-membrane interface that agree with experiment and atomistic simulations, including the potential of mean force for charged amino acid residuals at membrane. Consequently, the model predicts stable attachment of cationic peptides (i.e., poly-Arg) on lipid bilayer surface, which is not shown in previous models with non-electrostatic water.

  12. A double-taper optical fiber-based radiation wave other than evanescent wave in all-fiber immunofluorescence biosensor for quantitative detection of Escherichia coli O157:H7.

    PubMed

    Zhang, Zhonghuan; Hua, Fei; Liu, Ting; Zhao, Yong; Li, Jun; Yang, Ruifu; Yang, Changxi; Zhou, Lei

    2014-01-01

    Cylindrical or taper-and-cylinder combination optical fiber probe based on evanescent wave has been widely used for immunofluorescence biosensor to detect various analytes. In this study, in contrast to the contradiction between penetration depth and analyte diameter of optical fiber probe-based evanescent wave, we demonstrate that double-taper optical fiber used in a radiation wave-based all-fiber immunofluorescence biosensor (RWAIB) can detect micron-scale analytes using Escherichia coli O157:H7 as representative target. Finite-difference time-domain method was used to compare the properties of evanescent wave and radiation wave (RW). Ray-tracing model was formulated to optimize the taper geometry of the probe. Based on a commercial multi-mode fiber, a double-taper probe was fabricated and connected with biosensor through a "ferrule connector" optical fiber connector. The RWAIB configuration was accomplished using commercial multi-mode fibers and fiber-based devices according to the "all-fiber" method. The standard sample tests revealed that the sensitivity of the proposed technique for E. coli O157:H7 detection was 10(3) cfu · mL(-1). Quantitation could be achieved within the concentration range of 10(3) cfu · mL(-1) to 107 cfu · mL(-1). No non-specific recognition to ten kinds of food-borne pathogens was observed. The results demonstrated that based on the double-taper optical fiber RWAIB can be used for the quantitative detection of micron-scale targets, and RW sensing is an alternative for traditional evanescent wave sensing during the fabrication of fiber-optic biosensors.

  13. Fiber biology

    USDA-ARS?s Scientific Manuscript database

    Cotton fiber cells arising from seed epidermis is the most important agricultural textile commodity in the world. To produce fully mature fibers, approximately two months of fiber developmental process are required. The timing of four distinctive fiber development stages consisting of initiation, ...

  14. Mode-locked operation of Cr⁴⁺:YAG single-crystal fiber laser with external cavity.

    PubMed

    Ishibashi, Shigeo; Naganuma, Kazunori

    2014-03-24

    We report what is to our knowledge the first mode-locked Cr⁴⁺:YAG single-crystal fiber laser, which generates pulses of 120-fs duration with an output power of 23 mW at a center wavelength of 1520 nm for a single pulse in a cavity-round-trip. The laser contains a single-crystal fiber multi-mode waveguide about 120 μm in diameter and 40-mm long. The fundamental transverse mode is selected with an external cavity. This design strategy turned out to be well suited for direct high-power-laser-diode pumping.

  15. Localized surface plasmon resonance sensing structure based on gold nanohole array on beveled fiber edge.

    PubMed

    Zhao, Enming; Jia, Peipei; Ebendorff-Heidepriem, Heike; Li, Hanyang; Huang, Peng; Liu, Diyou; Li, Hanyang; Yang, Xinghua; Lu, Liu; Guan, Chunying

    2017-08-07

    This paper proposes a simple, stable, sensitive, and angle-dependent localized surface plasmon resonance (LSPR) sensing structure based on multi-mode optical fiber. We adopted the template transfer method to integrate a nanohole array onto a fiber tip with beveled angle. Experimental results indicated that beveled angle structured probe sensor outperform the flat optical fiber tip structured LSPR sensor in our experiment. We tested the sensitivity and the figure of merit (FOM) of the probe beveled angle from 5° to 22°, with refractive index ranging from 1.333 to 1.385, to find that sensitivity and FOM were optimal at fiber tip bevel angle of 7°, reaching 487 nm/RIU and 29 respectively. © 2017 IOP Publishing Ltd.

  16. Real-time measurement with a fiber optical surface plasmon resonance sensor for biochemical interaction analysis

    NASA Astrophysics Data System (ADS)

    Tan, Zhixin; Li, Xuejin; Chen, Yuzhi; Fan, Ping

    2013-08-01

    In this paper we report a fiber optical sensor system based on surface plasmon resonance (SPR) with real-time response for biochemical interaction analysis. The fiber sensor is constructed from a multi-mode fiber with plastic cladding. To facilitate the measurement, a software program is developed which integrates the data acquisition and processing for real-time feedback. Polynomial fitting is implemented to smooth out the noise in the transmission ratio and a spectral resolution of 0.2 nm is achieved. Ethyl alcohol and water mixtures with different concentrations are measured to demonstrate the system's real-time capability. This work is essential for the development of a compact, real-time fiber SPR biosensor.

  17. Fiber bundle probes for interconnecting miniaturized medical imaging devices

    NASA Astrophysics Data System (ADS)

    Zamora, Vanessa; Hofmann, Jens; Marx, Sebastian; Herter, Jonas; Nguyen, Dennis; Arndt-Staufenbiel, Norbert; Schröder, Henning

    2017-02-01

    Miniaturization of medical imaging devices will significantly improve the workflow of physicians in hospitals. Photonic integrated circuit (PIC) technologies offer a high level of miniaturization. However, they need fiber optic interconnection solutions for their functional integration. As part of European funded project (InSPECT) we investigate fiber bundle probes (FBPs) to be used as multi-mode (MM) to single-mode (SM) interconnections for PIC modules. The FBP consists of a set of four or seven SM fibers hexagonally distributed and assembled into a holder that defines a multicore connection. Such a connection can be used to connect MM fibers, while each SM fiber is attached to the PIC module. The manufacturing of these probes is explored by using well-established fiber fusion, epoxy adhesive, innovative adhesive and polishing techniques in order to achieve reliable, low-cost and reproducible samples. An innovative hydrofluoric acid-free fiber etching technology has been recently investigated. The preliminary results show that the reduction of the fiber diameter shows a linear behavior as a function of etching time. Different etch rate values from 0.55 μm/min to 2.3 μm/min were found. Several FBPs with three different type of fibers have been optically interrogated at wavelengths of 630nm and 1550nm. Optical losses are found of approx. 35dB at 1550nm for FBPs composed by 80μm fibers. Although FBPs present moderate optical losses, they might be integrated using different optical fibers, covering a broad spectral range required for imaging applications. Finally, we show the use of FBPs as promising MM-to-SM interconnects for real-world interfacing to PIC's.

  18. Reliability, failure modes, and degradation mechanisms in high power single- and multi-mode InGaAs-AlGaAs strained quantum well lasers

    NASA Astrophysics Data System (ADS)

    Sin, Yongkun; Presser, Nathan; Lingley, Zachary; Brodie, Miles; Foran, Brendan; Moss, Steven C.

    2016-03-01

    High power single-mode (SM) and multi-mode (MM) InGaAs-AlGaAs strained quantum well (QW) lasers are critical components for both telecommunications and potential space satellite communications systems. However, little has been reported on failure modes of state-of-the-art SM InGaAs-AlGaAs strained QW lasers although it is crucial to understand failure modes and underlying degradation mechanisms in developing these lasers that meet lifetime requirements for space satellite systems, where extremely high reliability of these lasers is required. Our present study addresses the aforementioned issues by performing long-term life tests under different test conditions followed by failure mode analysis (FMA) and physics of failure investigation. We performed long-term accelerated life-tests on state-of-the-art SM and MM InGaAs-AlGaAs strained QW lasers under ACC (automatic current control) mode. Our life-tests have accumulated over 25,000 test hours for SM lasers and over 35,000 test hours for MM lasers. FMA was performed on failed SM lasers using electron beam induced current (EBIC). This technique allowed us to identify failure types by observing dark line defects. All the SM failures we studied showed catastrophic and sudden degradation and all of these failures were bulk failures. Our group previously reported that bulk failure or COBD (catastrophic optical bulk damage) is the dominant failure mode of MM InGaAs-AlGaAs strained QW lasers. To the best of our knowledge, this is the first report demonstrating that the dominant failure mode of both SM and MM InGaAs-AlGaAs strained QW lasers is the bulk failure. Since degradation mechanisms responsible for COBD are still not well understood, we also employed other techniques including focused ion beam (FIB) processing and high-resolution TEM to further study dark line defects and dislocations in post-aged SM and MM lasers. Our long-term life test results and FMA results are reported.

  19. Natural fibers

    Treesearch

    Craig M. Clemons

    2010-01-01

    The term “natural fibers” covers a broad range of vegetable, animal, and mineral fibers. However, in the composites industry, it usually refers to wood fiber and plant-based bast, leaf, seed, and stem fibers. These fibers often contribute greatly to the structural performance of the plant and, when used in plastic composites, can provide significant reinforcement....

  20. Mineralogical and microscopic evaluation of coarse taconite tailings from Minnesota taconite operations.

    PubMed

    Zanko, Lawrence M; Niles, Harlan B; Oreskovich, Julie A

    2008-10-01

    Eighteen coarse taconite tailings samples were collected in 2000-2001 from five western Mesabi Range taconite (iron ore) operations located in northern Minnesota, i.e., EVTAC, Hibbing Taconite (Hibtac), USX Minntac, Ispat Inland (Minorca), and National Steel Pellet Company (NSPC), to test their physical, geological, chemical, and mineralogical properties [Zanko, L.M., Niles, H.B., Oreskovich, J.A., 2003. Properties and aggregate potential of coarse taconite tailings from five Minnesota taconite operations, Minnesota Department of Transportation, Local Road Research Board, St. Paul, MN, Report No. 2004-06 (also as Natural Resources Research Institute technical report, NRRI/TR-2003/44)]. The goal was to assemble a body of technical data that could be used to better assess the potential of using a crushed taconite mining byproduct like coarse tailings for more widespread construction aggregate purposes, primarily in roads and highways. An important part of the mineralogical assessment included X-ray diffraction (XRD) analyses and microscopic (polarized light microscopy, scanning electron microscopy, and transmission electron microscopy, i.e., PLM, SEM, and TEM, respectively) evaluation of the size and shape (morphological) characteristics of potentially respirable microscopic mineral particles and fragments. Quantitative mineralogy, based on XRD analyses, showed that the dominant mineral in all samples was quartz (55-60%), followed by much smaller amounts of iron oxides, carbonates, and silicates. Specialized microscopic analyses and testing performed by the RJ Lee Group, Monroeville, PA, on both pulverized (-200 mesh, or 0.075mm) and as-is sample composites showed that no regulated asbestos minerals or amphibole minerals were detected in the western Mesabi Range samples. A small number (26) of non-asbestos and non-amphibole mineral cleavage fragments/mineral fibers were detected by SEM out of 1000 fields analyzed, but most were identified as minnesotaite and talc

  1. Tunable Er-doped fiber ring laser with single longitudinal mode operation based on Rayleigh backscattering in single mode fiber.

    PubMed

    Yin, Guolu; Saxena, Bhavaye; Bao, Xiaoyi

    2011-12-19

    A tunable and single longitudinal mode Er-doped fiber ring laser (SLM-EDFRL) is proposed and demonstrated based on Rayleigh backscattering (RBS) in single mode fiber-28e (SMF-28e). Theory and experimental study on formation of SLM from normal multi-mode ring laser is demonstrated. The RBS feedback in 660 m SMF-28e is the key to ensure SLM laser oscillation. This tunable SLM laser can be tuned over 1549.7-1550.18 nm with a linewidth of 2.5-3.0 kHz and a side mode suppression ratio (SMSR) of ~72 dB for electrical signal power. The tuning range is determined by the bandpass filter and gain medium used in the experiment. The laser is able to operate at S+C+L band.

  2. Utilizing ytterbium- and erbium-doped fibers for a selectable and stable single-longitudinal-mode fiber ring laser

    NASA Astrophysics Data System (ADS)

    Yeh, Chien-Hung; Tsai, Ning; Zhuang, Yuan-Hong

    2016-05-01

    In this paper, a stable and wavelength-tunable C-band erbium-doped fiber (EDF) ring laser is experimentally demonstrated. Here, utilizing an unpumped ytterbium-doped fiber with a length of 0.6 m inside the ring cavity serving as a spatial multi-mode interference is proposed to suppress the multi-longitudinal-mode for single-longitudinal-mode output. Therefore, the output powers and optical signal-to-noise ratios of the proposed EDF ring laser are between  -11.74 and  -4.65 dBm and 34.3 and 26.9 dB, respectively. Moreover, the output performance of stability is also analyzed and discussed.

  3. Molecular Approaches to Understand Nutritional Potential of Coarse Cereals.

    PubMed

    Singh, Amit Kumar; Singh, Rakesh; Subramani, Rajkumar; Kumar, Rajesh; Wankhede, Dhammaprakash P

    2016-06-01

    Coarse grains are important group of crops that constitutes staple food for large population residing primarily in the arid and semi-arid regions of the world. Coarse grains are designated as nutri-cereals as they are rich in essential amino acids, minerals and vitamins. In spite of having several nutritional virtues in coarse grain as mentioned above, there is still scope for improvement in quality parameters such as cooking qualities, modulation of nutritional constituents and reduction or elimination of anti-nutritional factors. Besides its use in traditional cooking, coarse grains have been used mainly in the weaning food preparation and other malted food production. Improvement in quality parameters will certainly increase consumer's preference for coarse grains and increase their demand. The overall genetic gain in quality traits of economic importance in the cultivated varieties will enhance their industrial value and simultaneously increase income of farmers growing these varieties. The urgent step for improvement of quality traits in coarse grains requires a detailed understanding of molecular mechanisms responsible for varied level of different nutritional contents in different genotypes of these crops. In this review we have discussed the progresses made in understanding of coarse grain biology with various omics tool coupled with modern breeding approaches and the current status with regard to our effort towards dissecting traits related to improvement of quality and nutritional constituents of grains.

  4. Molecular Approaches to Understand Nutritional Potential of Coarse Cereals

    PubMed Central

    Singh, Amit Kumar; Singh, Rakesh; Subramani, Rajkumar; Kumar, Rajesh; Wankhede, Dhammaprakash P.

    2016-01-01

    Coarse grains are important group of crops that constitutes staple food for large population residing primarily in the arid and semi-arid regions of the world. Coarse grains are designated as nutri-cereals as they are rich in essential amino acids, minerals and vitamins. In spite of having several nutritional virtues in coarse grain as mentioned above, there is still scope for improvement in quality parameters such as cooking qualities, modulation of nutritional constituents and reduction or elimination of anti-nutritional factors. Besides its use in traditional cooking, coarse grains have been used mainly in the weaning food preparation and other malted food production. Improvement in quality parameters will certainly increase consumer’s preference for coarse grains and increase their demand. The overall genetic gain in quality traits of economic importance in the cultivated varieties will enhance their industrial value and simultaneously increase income of farmers growing these varieties. The urgent step for improvement of quality traits in coarse grains requires a detailed understanding of molecular mechanisms responsible for varied level of different nutritional contents in different genotypes of these crops. In this review we have discussed the progresses made in understanding of coarse grain biology with various omics tool coupled with modern breeding approaches and the current status with regard to our effort towards dissecting traits related to improvement of quality and nutritional constituents of grains. PMID:27252585

  5. Non-Galerkin Coarse Grids for Algebraic Multigrid

    SciTech Connect

    Falgout, Robert D.; Schroder, Jacob B.

    2014-06-26

    Algebraic multigrid (AMG) is a popular and effective solver for systems of linear equations that arise from discretized partial differential equations. And while AMG has been effectively implemented on large scale parallel machines, challenges remain, especially when moving to exascale. Particularly, stencil sizes (the number of nonzeros in a row) tend to increase further down in the coarse grid hierarchy, and this growth leads to more communication. Therefore, as problem size increases and the number of levels in the hierarchy grows, the overall efficiency of the parallel AMG method decreases, sometimes dramatically. This growth in stencil size is due to the standard Galerkin coarse grid operator, $P^T A P$, where $P$ is the prolongation (i.e., interpolation) operator. For example, the coarse grid stencil size for a simple three-dimensional (3D) seven-point finite differencing approximation to diffusion can increase into the thousands on present day machines, causing an associated increase in communication costs. We therefore consider algebraically truncating coarse grid stencils to obtain a non-Galerkin coarse grid. First, the sparsity pattern of the non-Galerkin coarse grid is determined by employing a heuristic minimal “safe” pattern together with strength-of-connection ideas. Second, the nonzero entries are determined by collapsing the stencils in the Galerkin operator using traditional AMG techniques. The result is a reduction in coarse grid stencil size, overall operator complexity, and parallel AMG solve phase times.

  6. Residential indoor and outdoor coarse particles and associated endotoxin exposures

    NASA Astrophysics Data System (ADS)

    Wheeler, Amanda J.; Dobbin, Nina A.; Lyrette, Ninon; Wallace, Lance; Foto, Mark; Mallick, Ranjeeta; Kearney, Jill; Van Ryswyk, Keith; Gilbert, Nicolas L.; Harrison, Ian; Rispler, Kathleen; Héroux, Marie-Eve

    2011-12-01

    There is a growing body of evidence demonstrating that coarse particles (PM 10-2.5) have detrimental impacts upon health, especially for respiratory effects. There are limited data available for indoor residential exposures. Some data exist regarding the composition of this PM size fraction with emphasis on crustal elements and biological components. This study includes data from 146 homes sampled in Regina, Saskatchewan (SK) where 5-day integrated concurrent monitoring of indoor and outdoor coarse particles was conducted during the winter and summer of 2007. The coarse particle filters were subsequently analysed for endotoxin content to determine the contribution of this compound. Winter indoor geometric mean concentrations of coarse particles exceeded outdoor concentrations (3.73 μg m -3 vs 2.49 μg m -3; paired t-test p < 0.0001); however the reverse was found in summer (4.34 μg m -3 vs 8.82 μg m -3; paired t-test p < 0.0001). Linear regression indicated that winter predictors of indoor coarse particles were outdoor coarse particles, ventilation and presence of at least two or more occupants. During the summer, increased use of central air conditioning was associated with reduced coarse particles, while smoking and the presence of two or more occupants resulted in increased coarse particles. Endotoxin concentrations (EU μg -1) were lower indoors than outdoors in both seasons. Spatial variability of ambient coarse particles was assessed to determine the suitability of using a single monitoring station within a city to estimate exposure. The coefficients of variation between homes sampled simultaneously and the central monitoring station were calculated (median COV in summer = 15% and winter = 24%) and showed significant variability by week, especially during the summer months, suggesting a single site may be insufficient for characterizing exposure. Future studies should consider daily measurements per home to understand shorter term exposures and day to day

  7. Development of a numerical tool to study the mixing phenomenon occurring during mode one operation of a multi-mode ejector-augmented pulsed detonation rocket engine

    NASA Astrophysics Data System (ADS)

    Dawson, Joshua

    A novel multi-mode implementation of a pulsed detonation engine, put forth by Wilson et al., consists of four modes; each specifically designed to capitalize on flow features unique to the various flow regimes. This design enables the propulsion system to generate thrust through the entire flow regime. The Multi-Mode Ejector-Augmented Pulsed Detonation Rocket Engine operates in mode one during take-off conditions through the acceleration to supersonic speeds. Once the mixing chamber internal flow exceeds supersonic speed, the propulsion system transitions to mode two. While operating in mode two, supersonic air is compressed in the mixing chamber by an upstream propagating detonation wave and then exhausted through the convergent-divergent nozzle. Once the velocity of the air flow within the mixing chamber exceeds the Chapman-Jouguet Mach number, the upstream propagating detonation wave no longer has sufficient energy to propagate upstream and consequently the propulsive system shifts to mode three. As a result of the inability of the detonation wave to propagate upstream, a steady oblique shock system is established just upstream of the convergent-divergent nozzle to initiate combustion. And finally, the propulsion system progresses on to mode four operation, consisting purely of a pulsed detonation rocket for high Mach number flight and use in the upper atmosphere as is needed for orbital insertion. Modes three and four appear to be a fairly significant challenge to implement, while the challenge of implementing modes one and two may prove to be a more practical goal in the near future. A vast number of potential applications exist for a propulsion system that would utilize modes one and two, namely a high Mach number hypersonic cruise vehicle. There is particular interest in the dynamics of mode one operation, which is the subject of this research paper. Several advantages can be obtained by use of this technology. Geometrically the propulsion system is fairly

  8. Fiber coupling and field mixing of coherent free-space optical beams in satellite communications

    NASA Astrophysics Data System (ADS)

    Poliak, J.; Giggenbach, D.; Mata Calvo, R.; Bok, D.

    2016-03-01

    Effective coupling of the optical field from free-space to optical fiber is an essential prerequisite for modern free-space optical communications systems. It allows for easier system integration with active and passive optical fiber-coupled components as well as for efficient optical field mixing for coherent communications. While coupling into single-mode fiber provides the advantage of using low-noise erbium-doped fiber preamplifiers, its relatively small mode field diameter limits achievable fiber coupling efficiency. Coupling into multimode fiber (MMF) increases the fiber coupling efficiency while introducing other spurious effects the authors have set out to analyze. The study of free-space optical beam coupling in the context of satellite communications will be presented. Here, we assume satellite link scenarios with different elevations, which correspond to different index-of-refraction turbulence (IRT) conditions. IRT gives rise to both intensity and phase aberration of the received optical field, which then causes extended speckle patterns in the focus of the receiver telescope. The speckle field at the fiber input is calculated by means of Fourier transform of the received field. Using dedicated modelling software, study of the fiber coupling efficiency, polarization preservation and high-order mode coupling in different multi-mode fibers is carried out.

  9. Continuous wave stimulated Brillouin scattering phase conjugation and beam cleanup in optical fiber

    NASA Astrophysics Data System (ADS)

    Massey, Steven M.; Spring, Justin B.; Russell, Timothy H.

    2009-02-01

    A review of research into stimulated Brillouin scattering (SBS) phase conjugation and beam cleanup conducted at the Air Force Institute of Technology is presented. CW phase conjugation was demonstrated using SBS in short lengths of multi-mode, step-index fiber. A fidelity of 0.8 was achieved using a 0.06-NA fiber of 40 m length and a 0.13-NA fiber at 15 m length. In modeling and experiment, the fidelity declined as fiber length or numerical aperture increased. A relationship was established empirically between step-index fiber parameters and the phase conjugation fidelity. In addition, increased fidelity was related to an increase in the effective Brillouin gain coefficient in step-index fibers. Beam cleanup was observed in both graded-index and step-index fibers. The Stokes beam generated in long, multimode, graded-index fibers was analyzed using spatial and phase methods and found to be a low-order mode of the fiber instead of a phase conjugate of the pump. SBS in long, graded-index fibers was used to combine multiple beams and to improve the beam quality of a single aberrated beam.

  10. A 1-Joule laser for a 16-fiber injection system

    SciTech Connect

    Honig, J

    2004-04-06

    A 1-J laser was designed to launch light down 16, multi-mode fibers (400-{micro}m-core dia.). A diffractive-optic splitter was designed in collaboration with Digital Optics Corporation (DOC), and was delivered by DOC. Using this splitter, the energy injected into each fiber varied <1%. The spatial profile out of each fiber was such that there were no ''hot spots,'' a flyer could successfully be launched and a PETN pellet could be initiated. Preliminary designs of the system were driven by system efficiency where a pristine TEM{sub 00} laser beam would be required. The laser is a master oscillator, power amplifier (MOPA) consisting of a 4-mm-dia. Nd:YLF rod in the stable, q-switched oscillator and a 9.5-mm-dia. Nd:YLF rod in the double-passed amplifier. Using a TEM{sub 00} oscillator beam resulted in excellent transmission efficiencies through the fibers at lower energies but proved to be quite unreliable at higher energies, causing premature fiber damage, flyer plate rupture, stimulated Raman scattering (SRS), and stimulated Brillouin scattering (SBS). Upon further investigation, it was found that both temporal and spatial beam formatting of the laser were required to successfully initiate the PETN. Results from the single-mode experiments, including fiber damage, SRS and SBS losses, will be presented. In addition, results showing the improvement that can be obtained by proper laser beam formatting will also be presented.

  11. Accurate numerical simulation of short fiber optical parametric amplifiers.

    PubMed

    Marhic, M E; Rieznik, A A; Kalogerakis, G; Braimiotis, C; Fragnito, H L; Kazovsky, L G

    2008-03-17

    We improve the accuracy of numerical simulations for short fiber optical parametric amplifiers (OPAs). Instead of using the usual coarse-step method, we adopt a model for birefringence and dispersion which uses fine-step variations of the parameters. We also improve the split-step Fourier method by exactly treating the nonlinear ellipse rotation terms. We find that results obtained this way for two-pump OPAs can be significantly different from those obtained by using the usual coarse-step fiber model, and/or neglecting ellipse rotation terms.

  12. A coarse-grained model for PETN crystals

    SciTech Connect

    Gee, R; Wu, C; Maiti, A

    2006-02-10

    Using the energetic material Pentaerythritol Tetranitrate (PETN) as a specific example of molecular crystal, we describe the development of a simple coarse-graining procedure by grouping several atoms or whole functional groups into single charge-neutral beads. As compared to fully atomistic calculations the coarse-grained model speeds up simulations by more than two orders of magnitude. Yet, by adjusting only two parameters in the coarse-grained interaction, the model accurately predicts the lattice constants, sublimation energy, pressure-volume curve up to P=10 GPa, and energetically the most stable facets. Computed surface and desorption energies, bulk modulus, and equilibrium morphology are reported as well.

  13. Coarse-grained Simulations of Viral Assembly

    NASA Astrophysics Data System (ADS)

    Elrad, Oren M.

    2011-12-01

    The formation of viral capsids is a marvel of natural engineering and design. A large number (from 60 to thousands) of protein subunits assemble into complete, reproducible structures under a variety of conditions while avoiding kinetic and thermodynamic traps. Small single-stranded RNA viruses not only assemble their coat proteins in this fashion but also package their genome during the self-assembly process. Recent experiments have shown that the coat proteins are competent to assemble not merely around their own genomes but heterologous RNA, synthetic polyanions and even functionalized gold nanoparticles. Remarkably these viruses can even assemble around cargo not commensurate with their native state by adopting different morphologies. Understanding the properties that confer such exquisite precision and flexibility to the assembly process could aid biomedical research in the search for novel antiviral remedies, drug-delivery vehicles and contrast agents used in bioimaging. At the same time, viral assembly provides an excellent model system for the development of a statistical mechanical understanding of biological self-assembly, in the hopes of that we will identify some universal principles that underly such processes. This work consists of computational studies using coarse-grained representations of viral coat proteins and their cargoes. We find the relative strength of protein-cargo and protein-protein interactions has a profound effect on the assembly pathway, in some cases leading to assembly mechanisms that are markedly different from those found in previous work on the assembly of empty capsids. In the case of polymeric cargo, we find the first evidence for a previously theorized mechanism in which the polymer actively participates in recruiting free subunits to the assembly process through cooperative polymer-protein motions. We find that successful assembly is non-monotonic in protein-cargo affinity, such affinity can be detrimental to assembly if it

  14. Mimicking coarse-grained simulations without coarse-graining: Enhanced sampling by damping short-range interactions

    NASA Astrophysics Data System (ADS)

    Wei, Dongshan; Wang, Feng

    2010-08-01

    The damped-short-range-interaction (DSRI) method is proposed to mimic coarse-grained simulations by propagating an atomistic scale system on a smoothed potential energy surface. The DSRI method has the benefit of enhanced sampling provided by a typical coarse-grained simulation without the need to perform coarse-graining. Our method was used to simulate liquid water, alanine dipeptide folding, and the self-assembly of dimyristoylphosphatidylcholine lipid. In each case, our method appreciably accelerated the dynamics without significantly changing the free energy surface. Additional insights from DSRI simulations and the promise of coupling our DSRI method with Hamiltonian replica-exchange molecular dynamics are discussed.

  15. Two-level method with coarse space size independent convergence

    SciTech Connect

    Vanek, P.; Brezina, M.; Tezaur, R.; Krizkova, J.

    1996-12-31

    The basic disadvantage of the standard two-level method is the strong dependence of its convergence rate on the size of the coarse-level problem. In order to obtain the optimal convergence result, one is limited to using a coarse space which is only a few times smaller than the size of the fine-level one. Consequently, the asymptotic cost of the resulting method is the same as in the case of using a coarse-level solver for the original problem. Today`s two-level domain decomposition methods typically offer an improvement by yielding a rate of convergence which depends on the ratio of fine and coarse level only polylogarithmically. However, these methods require the use of local subdomain solvers for which straightforward application of iterative methods is problematic, while the usual application of direct solvers is expensive. We suggest a method diminishing significantly these difficulties.

  16. Spectral coarse graining for random walks in bipartite networks.

    PubMed

    Wang, Yang; Zeng, An; Di, Zengru; Fan, Ying

    2013-03-01

    Many real-world networks display a natural bipartite structure, yet analyzing and visualizing large bipartite networks is one of the open challenges in complex network research. A practical approach to this problem would be to reduce the complexity of the bipartite system while at the same time preserve its functionality. However, we find that existing coarse graining methods for monopartite networks usually fail for bipartite networks. In this paper, we use spectral analysis to design a coarse graining scheme specific for bipartite networks, which keeps their random walk properties unchanged. Numerical analysis on both artificial and real-world networks indicates that our coarse graining can better preserve most of the relevant spectral properties of the network. We validate our coarse graining method by directly comparing the mean first passage time of the walker in the original network and the reduced one.

  17. Innovations in the flotation of fine and coarse particles

    NASA Astrophysics Data System (ADS)

    Fornasiero, D.; Filippov, L. O.

    2017-07-01

    Research on the mechanisms of particle-bubble interaction has provided valuable information on how to improve the flotation of fine (<20 µm) and coarse particles (>100 µm) with novel flotation machines which provide higher collision and attachment efficiencies of fine particles with bubbles and lower detachment of the coarse particles. Also, new grinding methods and technologies have reduced energy consumption in mining and produced better mineral liberation and therefore flotation performance.

  18. Fiber Techniques

    ERIC Educational Resources Information Center

    Nalle, Leona

    1976-01-01

    Describes a course in fiber techniques, which covers design methods involving fibers and fabric, that students in the Art Department at Sleeping Giant Junior High School had the opportunity to learn. (Author/RK)

  19. Highly Coarse-Grained Representations of Transmembrane Proteins

    PubMed Central

    2017-01-01

    Numerous biomolecules and biomolecular complexes, including transmembrane proteins (TMPs), are symmetric or at least have approximate symmetries. Highly coarse-grained models of such biomolecules, aiming at capturing the essential structural and dynamical properties on resolution levels coarser than the residue scale, must preserve the underlying symmetry. However, making these models obey the correct physics is in general not straightforward, especially at the highly coarse-grained resolution where multiple (∼3–30 in the current study) amino acid residues are represented by a single coarse-grained site. In this paper, we propose a simple and fast method of coarse-graining TMPs obeying this condition. The procedure involves partitioning transmembrane domains into contiguous segments of equal length along the primary sequence. For the coarsest (lowest-resolution) mappings, it turns out to be most important to satisfy the symmetry in a coarse-grained model. As the resolution is increased to capture more detail, however, it becomes gradually more important to match modular repeats in the secondary structure (such as helix-loop repeats) instead. A set of eight TMPs of various complexity, functionality, structural topology, and internal symmetry, representing different classes of TMPs (ion channels, transporters, receptors, adhesion, and invasion proteins), has been examined. The present approach can be generalized to other systems possessing exact or approximate symmetry, allowing for reliable and fast creation of multiscale, highly coarse-grained mappings of large biomolecular assemblies. PMID:28043122

  20. Bayesian parametrization of coarse-grain dissipative dynamics models

    NASA Astrophysics Data System (ADS)

    Dequidt, Alain; Solano Canchaya, Jose G.

    2015-08-01

    We introduce a new bottom-up method for the optimization of dissipative coarse-grain models. The method is based on Bayesian optimization of the likelihood to reproduce a coarse-grained reference trajectory obtained from analysis of a higher resolution molecular dynamics trajectory. This new method is related to force matching techniques, but using the total force on each grain averaged on a coarse time step instead of instantaneous forces. It has the advantage of not being limited to pairwise short-range interactions in the coarse-grain model and also yields an estimation of the friction parameter controlling the dynamics. The theory supporting the method is exposed in a practical perspective, with an analytical solution for the optimal set of parameters. The method was first validated by using it on a system with a known optimum. The new method was then tested on a simple system: n-pentane. The local molecular structure of the optimized model is in excellent agreement with the reference system. An extension of the method allows to get also an excellent agreement for the equilibrium density. As for the dynamic properties, they are also very satisfactory, but more sensitive to the choice of the coarse-grain representation. The quality of the final force field depends on the definition of the coarse grain degrees of freedom and interactions. We consider this method as a serious alternative to other methods like iterative Boltzmann inversion, force matching, and Green-Kubo formulae.

  1. Energy-conserving coarse-graining of complex molecules.

    PubMed

    Español, Pep; Serrano, Mar; Pagonabarraga, Ignacio; Zúñiga, Ignacio

    2016-05-25

    Coarse-graining (CG) of complex molecules is a method to reach time scales that would be impossible to access through brute force molecular simulations. In this paper, we formulate a coarse-grained model for complex molecules using first principles caculations that ensures energy conservation. Each molecule is described in a coarse way by a thermal blob characterized by the position and momentum of the center of mass of the molecule, together with its internal energy as an additional degree of freedom. This level of description gives rise to an entropy-based framework instead of the usual one based on the configurational free energy (i.e. potential of mean force). The resulting dynamic equations, which account for an appropriate description of heat transfer at the coarse-grained level, have the structure of the dissipative particle dynamics with energy conservation (DPDE) model but with a clear microscopic underpinning. Under suitable approximations, we provide explicit microscopic expressions for each component (entropy, mean force, friction and conductivity coefficients) appearing in the coarse-grained model. These quantities can be computed directly using MD simulations. The proposed non-isothermal coarse-grained model is thermodynamically consistent and opens up a first principles CG strategy for the study of energy transport issues that are not accessible using current isothermal models.

  2. Interlaced coarse-graining for the dynamical cluster approximation

    NASA Astrophysics Data System (ADS)

    Haehner, Urs; Staar, Peter; Jiang, Mi; Maier, Thomas; Schulthess, Thomas

    The negative sign problem remains a challenging limiting factor in quantum Monte Carlo simulations of strongly correlated fermionic many-body systems. The dynamical cluster approximation (DCA) makes this problem less severe by coarse-graining the momentum space to map the bulk lattice to a cluster embedded in a dynamical mean-field host. Here, we introduce a new form of an interlaced coarse-graining and compare it with the traditional coarse-graining. We show that it leads to more controlled results with weaker cluster shape and smoother cluster size dependence, which with increasing cluster size converge to the results obtained using the standard coarse-graining. In addition, the new coarse-graining reduces the severity of the fermionic sign problem. Therefore, it enables calculations on much larger clusters and can allow the evaluation of the exact infinite cluster size result via finite size scaling. To demonstrate this, we study the hole-doped two-dimensional Hubbard model and show that the interlaced coarse-graining in combination with the DCA+ algorithm permits the determination of the superconducting Tc on cluster sizes, for which the results can be fitted with the Kosterlitz-Thouless scaling law. This research used resources of the Oak Ridge Leadership Computing Facility (OLCF) awarded by the INCITE program, and of the Swiss National Supercomputing Center. OLCF is a DOE Office of Science User Facility supported under Contract DE-AC05-00OR22725.

  3. Source identification of coarse particles in the Desert ...

    EPA Pesticide Factsheets

    The Desert Southwest Coarse Particulate Matter Study was undertaken to further our understanding of the spatial and temporal variability and sources of fine and coarse particulate matter (PM) in rural, arid, desert environments. Sampling was conducted between February 2009 and February 2010 in Pinal County, AZ near the town of Casa Grande where PM concentrations routinely exceed the U.S. National Ambient Air Quality Standards (NAAQS) for both PM10 and PM2.5. In this desert region, exceedances of the PM10 NAAQS are dominated by high coarse particle concentrations, a common occurrence in this region of the United States. This work expands on previously published measurements of PM mass and chemistry by examining the sources of fine and coarse particles and the relative contribution of each to ambient PM mass concentrations using the Positive Matrix Factorization receptor model (Clements et al., 2014). Highlights • Isolation of coarse particles from fine particle sources. • Unique chemical composition of coarse particles. • Role of primary biological particles on aerosol loadings.

  4. Dietary Fiber

    MedlinePlus

    Fiber is a substance in plants. Dietary fiber is the kind you eat. It's a type of carbohydrate. You may also see it listed on a food label as soluble ... types have important health benefits. Good sources of dietary fiber include Whole grains Nuts and seeds Fruit and ...

  5. Wavelets as basis functions to represent the coarse-graining potential in multiscale coarse graining approach

    SciTech Connect

    Maiolo, M.; Vancheri, A.; Krause, R.; Danani, A.

    2015-11-01

    In this paper, we apply Multiresolution Analysis (MRA) to develop sparse but accurate representations for the Multiscale Coarse-Graining (MSCG) approximation to the many-body potential of mean force. We rigorously framed the MSCG method into MRA so that all the instruments of this theory become available together with a multitude of new basis functions, namely the wavelets. The coarse-grained (CG) force field is hierarchically decomposed at different resolution levels enabling to choose the most appropriate wavelet family for each physical interaction without requiring an a priori knowledge of the details localization. The representation of the CG potential in this new efficient orthonormal basis leads to a compression of the signal information in few large expansion coefficients. The multiresolution property of the wavelet transform allows to isolate and remove the noise from the CG force-field reconstruction by thresholding the basis function coefficients from each frequency band independently. We discuss the implementation of our wavelet-based MSCG approach and demonstrate its accuracy using two different condensed-phase systems, i.e. liquid water and methanol. Simulations of liquid argon have also been performed using a one-to-one mapping between atomistic and CG sites. The latter model allows to verify the accuracy of the method and to test different choices of wavelet families. Furthermore, the results of the computer simulations show that the efficiency and sparsity of the representation of the CG force field can be traced back to the mathematical properties of the chosen family of wavelets. This result is in agreement with what is known from the theory of multiresolution analysis of signals.

  6. Experimental study on narrow linewidth fiber ring laser based on parallel feedback mechanism

    NASA Astrophysics Data System (ADS)

    Wang, Cui-yun; Wang, Da-liang; Wang, Zi-nan; Lu, Ping; Xu, Lian-yu; Yu, Xiao-qi; Jiang, Yun; Zhu, Li-xin; Li, Zheng-bin

    2011-06-01

    Narrow linewidth fiber lasers are intensively studied during these years, for their wide use in coherent optical communication, optical fiber sensing, high-precision spectroscopy and many other industrial and military applications. A usual technique to suppress linewidth is narrow band filtering in the resonating structure of the laser. However, it is hard in fabrication for a tradition optical filter to achieve an ultra narrow pass band such as kilo-Hertz. In this paper, the parallel feedback structure is proposed and experimentally studied. A fiber laser with ultra narrow linewidth (15Hz detected) is achieved in laboratory, basing on the parallel feedback mechanism in a fiber ring cavity. In multimode fiber, each transverse mode has a different propagation constant. Equivalently, when a light beam propagates form single mode fiber to multimode fiber, it will split into a few parallel light paths with different propagation constants. The parallel feedback structure of a fiber ring laser is carried out by introducing one or more pieces of multi-mode fiber into its resonant cavity. Lasing light in the cavity must fit the restrictions of all light paths, thus linewidth of the laser output is suppressed. Ultra narrow linewidth can be achieved by carefully adjusting the amount and length of multi-mode fiber pieces. The narrowest linewidth achieved in laboratory is 15Hz detected by a delayed self-heterodyne interferometer with a 100km fiber delay line. In this work, we focus on pressuring linewidth, and mechanism of selecting and stabilizing mode isn't employed. Therefore, the narrow linewidth fiber laser isn't single-longitudinal-mode (SLM). A similar ring laser structure with bidirectional output is also experimental implemented, achieving a bandwidth of the same order. The bidirectional ring laser is the basic component of a laser gyroscope, and its linewidth is one key limiting factor of the gyroscope accuracy. This narrow linewidth bidirectional ring laser is a

  7. Small form factor optical fiber connector evaluation for harsh environments

    NASA Astrophysics Data System (ADS)

    Ott, Melanie N.; Thomes, W. Joe, Jr.; Chuska, Richard F.; Switzer, Robert; Blair, Diana E.

    2011-09-01

    For the past decade NASA programs have utilized the Diamond AVIM connector for optical fiber assemblies on space flight instrumentation. These connectors have been used in communications, sensing and LIDAR systems where repeatability and high performance are required. Recently Diamond has released a smaller form factor optical fiber connector called the "Mini-AVIM" which although more compact still includes the tight tolerances and the ratcheting feature of the heritage AVIM. NASA Goddard Space Flight Center Photonics Group in the Parts, Packaging and Assembly Technologies Office has been performing evaluations of this connector to determine how it compares to the performance of the AVIM connector and to assess its feasibility for harsh environmental applications. Vibration and thermal testing were performed on the Mini-AVIM with both multi-mode and single-mode optical fiber using insitu optical transmission monitoring. Random vibration testing was performed using typical launch condition profiles for most NASA missions but extended to 35 Grms, which is much higher than most requirements. Thermal testing was performed incrementally up to a range of -55°C to +125°C. The test results include both unjacketed fiber and cabled assembly evaluations. The data presented here indicate that the Mini-AVIM provides a viable option for small form factor applications that require a high performance optical fiber connector.

  8. Systematic Coarse-graining of Molecular Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Voth, Gregory

    2015-03-01

    Coarse-grained (CG) models can provide a computationally efficient means to study biomolecular and other soft matter processes involving large numbers of atoms that are correlated over distance scales of many covalent bond lengths and at long time scales. Systematic variational coarse-graining methods based on information from molecular dynamics simulations of finer-grained (e.g., all-atom) models provide attractive tools for the systematic development of CG models. Examples include the multiscale coarse-graining (MS-CG) and relative entropy minimization methods, and results from the former theory will be presented in this talk. In addition, a new approach will be presented that is appropriate for the ``ultra coarse-grained'' (UCG) regime, e.g., at a coarse-grained resolution that is much coarser than one amino acid residue per CG particle in a protein. At this level of coarse-graining, one is faced with the possible existence of multiple metastable states ``within'' the CG sites for a given UCG model configuration. I will therefore describe newer systematic variational UCG methods specifically designed to CG entire protein domains and subdomains into single effective CG particles. This is accomplished by augmenting existing effective particle CG schemes to allow for discrete state transitions and configuration-dependent resolution. Additionally, certain aspects of this work connect back to single-state force matching and open up new avenues for method development. This general body of theory and algorithm provides a formal statistical mechanical basis for the coarse-graining of fine-grained molecular dynamics simulation data at various levels of CG resolution. Representative applications will be described as time allows.

  9. Advances in high-power 9XXnm laser diodes for pumping fiber lasers

    NASA Astrophysics Data System (ADS)

    Skidmore, Jay; Peters, Matthew; Rossin, Victor; Guo, James; Xiao, Yan; Cheng, Jane; Shieh, Allen; Srinivasan, Raman; Singh, Jaspreet; Wei, Cailin; Duesterberg, Richard; Morehead, James J.; Zucker, Erik

    2016-03-01

    A multi-mode 9XXnm-wavelength laser diode was developed to optimize the divergence angle and reliable ex-facet power. Lasers diodes were assembled into a multi-emitter pump package that is fiber coupled via spatial and polarization multiplexing. The pump package has a 135μm diameter output fiber that leverages the same optical train and mechanical design qualified previously. Up to ~ 270W CW power at 22A is achieved at a case temperature ~ 30ºC. Power conversion efficiency is 60% (peak) that drops to 53% at 22A with little thermal roll over. Greater than 90% of the light is collected at < 0.12NA at 16A drive current that produces 3.0W/(mm-mr)2 radiance from the output fiber.

  10. Silicon-on-sapphire fiber optic transceiver technology for space applications

    NASA Astrophysics Data System (ADS)

    Kuznia, C. P.; Ahadian, J. F.; Pommer, R. J.; Hagan, R.

    2007-09-01

    We present Single Event Upset (SEU) testing of a parallel fiber optic transceiver designed for communicating data using commercial Fibre Channel and GbE protocols at data rates up to 2.5 Gbps per channel (on eight parallel channels). This transceiver was developed for aircraft applications, such as the Joint Strike Fighter (JSF), Raptor and F/A-18 aircraft, that deploy fiber optic networks using multi-mode fiber operating at 850 nm wavelength. However, this transceiver may also have applications in space environments. This paper describes the underlying transceiver component technology, which utilizes complementary metal-oxide semiconductor (CMOS) silicon-onsapphire circuitry and GaAs VCSEL and PIN devices. We also present results of SEU testing of this transceiver using heavy ions at Brookhaven National Labs.

  11. Coreless side polished fiber as ultra-sensitive refractive index sensor

    NASA Astrophysics Data System (ADS)

    Dong, Huazhuo; Guan, Junwen; Yu, Jianhui; Lu, Huihui; Luo, Yunhan; Zhang, Jun; Chen, Zhe; Wu, Zhuoqi

    2016-04-01

    A novel type of coreless side-polished fiber (CSPF) was investigated numerically and experimentally for sensing refractive index (RI). Numerical simulations and experiments found that multi-mode interference can be excited at the transitional section of coreless side-polished fiber, leading to resonant dips in transmission spectrum through such a CSPF. A red shift of such dips was observed due to increase in surrounding RI, whereby the CSPF can be used as RI sensor. Interestingly, by such a simple CSPF structure, ultra-high sensitivity of 7225nm/RIU for RI range of 1.432 to 1.434 was achieved in our experiment. As the CSPF can act as a versatile platform, the high sensitivity of the CSPF will open new opportunities for other high sensitive sensors and fiber devices.

  12. Fiber-optic interferometer for surface profile measurement with vibration suppression.

    PubMed

    Kwon, Taekmin; Kim, Seung-Woo

    2011-02-28

    We describe an improved design of fiber-optic interferometer intended to measure surface profiles with enhanced capability of vibration suppression. The reference wavefront is generated directly from the measurement wave using a multi-mode fiber that eliminates only the spatial wavefront distortion by means of bend loss. The temporal fluctuation caused by vibration is consequently cancelled out in the process of interference since it becomes to exist in both the measurement and reference waves. Further, an injection locking technique is incorporated to stabilize the reference wave intensity and hence make stable the interferometric fringe intensity. Experimental result proves that the proposed fiber-optic interferometer is capable of producing sub-wavelength measurement precision even in the presence of severe vibration with 100-μm amplitude.

  13. NONLINEAR MULTIGRID SOLVER EXPLOITING AMGe COARSE SPACES WITH APPROXIMATION PROPERTIES

    SciTech Connect

    Christensen, Max La Cour; Villa, Umberto E.; Engsig-Karup, Allan P.; Vassilevski, Panayot S.

    2016-01-22

    The paper introduces a nonlinear multigrid solver for mixed nite element discretizations based on the Full Approximation Scheme (FAS) and element-based Algebraic Multigrid (AMGe). The main motivation to use FAS for unstruc- tured problems is the guaranteed approximation property of the AMGe coarse spaces that were developed recently at Lawrence Livermore National Laboratory. These give the ability to derive stable and accurate coarse nonlinear discretization problems. The previous attempts (including ones with the original AMGe method, [5, 11]), were less successful due to lack of such good approximation properties of the coarse spaces. With coarse spaces with approximation properties, our FAS approach on un- structured meshes should be as powerful/successful as FAS on geometrically re ned meshes. For comparison, Newton's method and Picard iterations with an inner state-of-the-art linear solver is compared to FAS on a nonlinear saddle point problem with applications to porous media ow. It is demonstrated that FAS is faster than Newton's method and Picard iterations for the experiments considered here. Due to the guaranteed approximation properties of our AMGe, the coarse spaces are very accurate, providing a solver with the potential for mesh-independent convergence on general unstructured meshes.

  14. Recycled Coarse Aggregate Produced by Pulsed Discharge in Water

    NASA Astrophysics Data System (ADS)

    Namihira, Takao; Shigeishi, Mitsuhiro; Nakashima, Kazuyuki; Murakami, Akira; Kuroki, Kaori; Kiyan, Tsuyoshi; Tomoda, Yuichi; Sakugawa, Takashi; Katsuki, Sunao; Akiyama, Hidenori; Ohtsu, Masayasu

    In Japan, the recycling ratio of concrete scraps has been kept over 98 % after the Law for the Recycling of Construction Materials was enforced in 2000. In the present, most of concrete scraps were recycled as the Lower Subbase Course Material. On the other hand, it is predicted to be difficult to keep this higher recycling ratio in the near future because concrete scraps increase rapidly and would reach to over 3 times of present situation in 2010. In addition, the demand of concrete scraps as the Lower Subbase Course Material has been decreased. Therefore, new way to reuse concrete scraps must be developed. Concrete scraps normally consist of 70 % of coarse aggregate, 19 % of water and 11 % of cement. To obtain the higher recycling ratio, the higher recycling ratio of coarse aggregate is desired. In this paper, a new method for recycling coarse aggregate from concrete scraps has been developed and demonstrated. The system includes a Marx generator and a point to hemisphere mesh electrode immersed in water. In the demonstration, the test piece of concrete scrap was located between the electrodes and was treated by the pulsed discharge. After discharge treatment of test piece, the recycling coarse aggregates were evaluated under JIS and TS and had enough quality for utilization as the coarse aggregate.

  15. Coarse graining atomistic simulations of plastically deforming amorphous solids

    NASA Astrophysics Data System (ADS)

    Hinkle, Adam R.; Rycroft, Chris H.; Shields, Michael D.; Falk, Michael L.

    2017-05-01

    The primary mode of failure in disordered solids results from the formation and persistence of highly localized regions of large plastic strains known as shear bands. Continuum-level field theories capable of predicting this mechanical response rely upon an accurate representation of the initial and evolving states of the amorphous structure. We perform molecular dynamics simulations of a metallic glass and propose a methodology for coarse graining discrete, atomistic quantities, such as the potential energies of the elemental constituents. A strain criterion is established and used to distinguish the coarse-grained degrees-of-freedom inside the emerging shear band from those of the surrounding material. A signal-to-noise ratio provides a means of evaluating the strength of the signal of the shear band as a function of the coarse graining. Finally, we investigate the effect of different coarse graining length scales by comparing a two-dimensional, numerical implementation of the effective-temperature description in the shear transformation zone (STZ) theory with direct molecular dynamics simulations. These comparisons indicate the coarse graining length scale has a lower bound, above which there is a high level of agreement between the atomistics and the STZ theory, and below which the concept of effective temperature breaks down.

  16. Characterizing and contrasting instream and riparian coarse wood in western Montana basins

    Treesearch

    Michael K. Young; Ethan A. Mace; Eric T. Ziegler; Elaine K. Sutherland

    2006-01-01

    The importance of coarse wood to aquatic biota and stream channel structure is widely recognized, yet characterizations of large-scale patterns in coarse wood dimensions and loads are rare. To address these issues, we censused instream coarse wood ( 2 m long and 10 cm minimum diameter) and sampled riparian coarse wood and channel characteristics in and along 13 streams...

  17. Specialty flat-top beam delivery fibers with controlled beam parameter product

    NASA Astrophysics Data System (ADS)

    Jollivet, C.; Farley, K.; Conroy, M.; Abramczyk, J.; Belke, S.; Becker, F.; Tankala, K.

    2016-03-01

    Beam delivery fibers have been used widely for transporting the optical beams from the laser to the subject of irradiation in a variety of markets including industrial, medical and defense applications. Standard beam delivery fibers range from 50 to 1500 μm core diameter and are used to guide CW or pulsed laser light, generated by solid state, fiber or diode lasers. Here, we introduce a novel fiber technology capable of simultaneously controlling the beam profile and the angular divergence of single-mode (SM) and multi-mode (MM) beams using a single-optical fiber. Results of beam transformation from a SM to a MM beam with flat-top intensity profile are presented in the case of a controlled BPP at 3.8 mm*mrad. The scaling capabilities of this flat-top fiber design to achieve a range of BPP values while ensuring a flat-top beam profile are discussed. In addition, we demonstrate, for the first time to the best of our knowledge, the homogenizer capabilities of this novel technology, able to transform random MM beams into uniform flat-top beam profiles with very limited impact on the beam brightness. This study is concluded with a discussion on the scalability of this fiber technology to fit from 50 up to 1500 μm core fibers and its potential for a broader range of applications.

  18. Insights on protein-DNA recognition by coarse grain modelling.

    PubMed

    Poulain, P; Saladin, A; Hartmann, B; Prévost, C

    2008-11-30

    Coarse grain modelling of macromolecules is a new approach, potentially well adapted to answer numerous issues, ranging from physics to biology. We propose here an original DNA coarse grain model specifically dedicated to protein-DNA docking, a crucial, but still largely unresolved, question in molecular biology. Using a representative set of protein-DNA complexes, we first show that our model is able to predict the interaction surface between the macromolecular partners taken in their bound form. In a second part, the impact of the DNA sequence and electrostatics, together with the DNA and protein conformations on docking is investigated. Our results strongly suggest that the overall DNA structure mainly contributes in discriminating the interaction site on cognate proteins. Direct electrostatic interactions between phosphate groups and amino acid side chains strengthen the binding. Overall, this work demonstrates that coarse grain modeling can reveal itself a precious auxiliary for a general and complete description and understanding of protein-DNA association mechanisms.

  19. Comparison of iterative inverse coarse-graining methods

    NASA Astrophysics Data System (ADS)

    Rosenberger, David; Hanke, Martin; van der Vegt, Nico F. A.

    2016-10-01

    Deriving potentials for coarse-grained Molecular Dynamics (MD) simulations is frequently done by solving an inverse problem. Methods like Iterative Boltzmann Inversion (IBI) or Inverse Monte Carlo (IMC) have been widely used to solve this problem. The solution obtained by application of these methods guarantees a match in the radial distribution function (RDF) between the underlying fine-grained system and the derived coarse-grained system. However, these methods often fail in reproducing thermodynamic properties. To overcome this deficiency, additional thermodynamic constraints such as pressure or Kirkwood-Buff integrals (KBI) may be added to these methods. In this communication we test the ability of these methods to converge to a known solution of the inverse problem. With this goal in mind we have studied a binary mixture of two simple Lennard-Jones (LJ) fluids, in which no actual coarse-graining is performed. We further discuss whether full convergence is actually needed to achieve thermodynamic representability.

  20. Significance of coarse cereals in health and nutrition: a review.

    PubMed

    Kaur, Kiran Deep; Jha, Alok; Sabikhi, Latha; Singh, A K

    2014-08-01

    This review assesses the nutritional attributes of coarse cereals and also their utilization as food and as formulated foods. These cereals are laden with phytochemicals including phenolic acids, tannins, anthocyanins, phytosterols, avenenathramides and policosanols. They possess high antioxidant properties in vitro than staple cereals and fruits by different purported pathways. There are also some anti-nutritional factors that may be reduced by certain processing treatments. Several epidemiological studies show that these cereals are helpful in reducing several kinds of chronic diseases like cancers, cardiovascular diseases, type II diabetes and various gastrointestinal disorders. Being coarse in nature, they cannot replace our staple cereals, but can be used in different proportions with rice and wheat to formulate various nutritional products. They can be used to make porridges, biscuits, cakes, cookies, tortillas, bread, probiotic drinks, ladoo, ghatta, flakes and several fermented foods. The coarse cereals also have good potential in manufacturing bioethanol, paper, oil and biofilms.

  1. Obtaining fully dynamic coarse-grained models from MD.

    PubMed

    Español, Pep; Zúñiga, Ignacio

    2011-06-14

    We present a general method to obtain parametrised models for the drift and diffusion terms of the Fokker-Planck equation of a coarse-grained description of molecular systems. The method is based on the minimisation of the relative entropy defined in terms of the two-time joint probability and thus captures the full dynamics of the coarse-grained description. In addition, we show an alternative Bayesian argument that starts from the path probability of a diffusion process which allows one to obtain the best parametrised model that fits an actual observed path of the coarse-grained variables. Both approaches lead to exactly the same optimisation function giving strong support to the methodology. We provide an heuristic argument that explains how both approaches are connected.

  2. A Decoupled Finite Element Heterogeneous Coarse Mesh Transport Method.

    SciTech Connect

    Mosher, S. W.; Rahnema, Farzad

    2005-01-01

    In a recent paper, an original finite element (FE) method was presented for solving eigenvalue transport problems on a coarse spatial mesh. The method employed a surface Green's function expansion of the angular flux trial functions, so that heterogeneous coarse-meshes could be treated with relative ease. Numerical problems were solved using the multigroup discrete ordinates approximation in one-dimensional (1-D) slab geometry. Unfortunately, difficulties were encountered in finding solutions to the algebraic finite element equations, which led to sizeable angular flux discontinuities at coarse-mesh interfaces and significant errors. For this reason, a nonvariational iterative technique was ultimately favored for converging the angular flux distribution, and was used in conjunction with a Rayleigh quotient for converging the eigenvalue. In this paper, a new derivation of finite element equations is presented, which seems to offer a remedy for at least some of the numerical ills that plagued the previous work. First, the equations are derived in terms of a generalized response function expansion. This allows a more efficient response basis to be employed and vastly reduces the overall computational effort without a substantial loss of accuracy. Second, the tight coupling between coarse-meshes in the original equations is effectively broken by assuming that an accurate estimate of the flux distribution entering a given coarse-mesh is known. With an additional assumption that an accurate eigenvalue estimate is known, an iterative approach to solving these decoupled finite element (DFE) equations is developed. The DFE method has been applied to both 1- and 2-D heterogeneous coarse-mesh problems with a far greater degree of success than the original FE method. However, some numerical difficulties remain to be overcome before the new approach can be considered robust.

  3. Estimated glycemic index and dietary fiber content of cookies elaborated with extruded wheat bran.

    PubMed

    Reyes-Pérez, Faviola; Salazar-García, María Guadalupe; Romero-Baranzini, Ana Lourdes; Islas-Rubio, Alma Rosa; Ramírez-Wong, Benjamín

    2013-03-01

    The increasing demand for high-fiber products has favored the design of numerous bakery products rich in fiber such as bread, cookies, and cakes. The objective of this study was to evaluate the dietary fiber and estimated glycemic index of cookies containing extruded wheat bran. Wheat bran was subjected to extrusion process under three temperature profiles: TP1;(60, 75, 85 and 100 °C), TP2;(60, 80, 100 and 120 °C), and TP3;(60, 80, 110 and 140 °C) and three moisture contents: (15, 23, and 31 %). Cookies were elaborated using extruded wheat bran (30 %), separated into two fractions (coarse and fine). The dietary fiber content of cookies elaborated with extruded wheat bran was higher than the controls; C0 (100 % wheat flour) and C1 (30 % of no extruded bran coarse fraction) and C2 (30 % of no extruded bran fine fraction). The higher values of dietary fiber were observed on cookies from treatments 5 (TP1, 31 % moisture content and coarse fraction) and 11 (TP2, 31 % moisture content and coarse fraction). The estimated glycemic index of cookies ranged from 68.54 to 80.16. The dietary fiber content of cookies was increased and the lowest glycemic index corresponded to the cookies elaborated with extruded wheat bran. Cookie made with the treatment 11 had a better dietary fiber content and lower estimated glycemic index.

  4. Coarse-grid selection for parallel algebraic multigrid

    SciTech Connect

    Cleary, A. J., LLNL

    1998-06-01

    The need to solve linear systems arising from problems posed on extremely large, unstructured grids has sparked great interest in parallelizing algebraic multigrid (AMG) To date, however, no parallel AMG algorithms exist We introduce a parallel algorithm for the selection of coarse-grid points, a crucial component of AMG, based on modifications of certain paallel independent set algorithms and the application of heuristics designed to insure the quality of the coarse grids A prototype serial version of the algorithm is implemented, and tests are conducted to determine its effect on multigrid convergence, and AMG complexity

  5. The multiscale coarse-graining method. II. Numerical implementation for coarse-grained molecular models.

    PubMed

    Noid, W G; Liu, Pu; Wang, Yanting; Chu, Jhih-Wei; Ayton, Gary S; Izvekov, Sergei; Andersen, Hans C; Voth, Gregory A

    2008-06-28

    The multiscale coarse-graining (MS-CG) method [S. Izvekov and G. A. Voth, J. Phys. Chem. B 109, 2469 (2005); J. Chem. Phys. 123, 134105 (2005)] employs a variational principle to determine an interaction potential for a CG model from simulations of an atomically detailed model of the same system. The companion paper proved that, if no restrictions regarding the form of the CG interaction potential are introduced and if the equilibrium distribution of the atomistic model has been adequately sampled, then the MS-CG variational principle determines the exact many-body potential of mean force (PMF) governing the equilibrium distribution of CG sites generated by the atomistic model. In practice, though, CG force fields are not completely flexible, but only include particular types of interactions between CG sites, e.g., nonbonded forces between pairs of sites. If the CG force field depends linearly on the force field parameters, then the vector valued functions that relate the CG forces to these parameters determine a set of basis vectors that span a vector subspace of CG force fields. The companion paper introduced a distance metric for the vector space of CG force fields and proved that the MS-CG variational principle determines the CG force force field that is within that vector subspace and that is closest to the force field determined by the many-body PMF. The present paper applies the MS-CG variational principle for parametrizing molecular CG force fields and derives a linear least squares problem for the parameter set determining the optimal approximation to this many-body PMF. Linear systems of equations for these CG force field parameters are derived and analyzed in terms of equilibrium structural correlation functions. Numerical calculations for a one-site CG model of methanol and a molecular CG model of the EMIM(+)NO(3) (-) ionic liquid are provided to illustrate the method.

  6. Adiabatic circular polarizer based on chiral fiber grating.

    PubMed

    Yang, Li; Xue, Lin-Lin; Li, Cheng; Su, Jue; Qian, Jing-Ren

    2011-01-31

    Based on the adiabatic coupling principle, a new scheme of a broadband circular polarizer formed by twisting a high-birefringence (Hi-Bi) fiber with a slowly varying twist rate is proposed. The conditions of adiabatic coupling for the adiabatic polarizer are first identified through analytical derivations. These conditions are easily realized by choosing a reasonable variation of the twist rate. Moreover, the bandwidth of the polarizer is able to be directly determined by the twist rates at the two ends. Finally, the broadband characteristics of the polarizer are demonstrated by simulations. It is also shown that the performance of the polarizer can be remarkably improved by accomplishing a multi-mode phase-matching along the grating or by using of the couplings of the core mode to lossy modes.

  7. Coarse woody debris metrics in a California oak woodland

    Treesearch

    William D. Tietje; Michael A. Hardy; Christopher C. Yim

    2015-01-01

    Little information is available on the metrics of coarse woody debris (CWD) in California oak woodland, most notably at the scale of the stand and woodland type. In a remote part of the National Guard Post, Camp Roberts, that has not burned in over a half century, we tallied 314 pieces of CWD in a blue oak (Quercus douglasii)-coast live oak (

  8. Managing coarse woody debris in forests of the Rocky Mountains

    Treesearch

    Russell T. Graham; Alan E. Harvey; Martin F. Jurgensen; Theresa B. Jain; Jonalea R. Tonn; Deborah S. Page-Dumroese

    1994-01-01

    Recommendations for managing coarse woody debris after timber harvest were developed for 14 habitat types, ranging from ponderosa pine (Pinus ponderosa) habitat types of Arizona to subalpine fir (Abies lasiocarpa) habitat types of western Montana. Ectomycorrhizae were used as a bioindicator of healthy, productive forest soils....

  9. Coarse-graining stochastic biochemical networks: adiabaticity and fast simulations

    SciTech Connect

    Nemenman, Ilya; Sinitsyn, Nikolai; Hengartner, Nick

    2008-01-01

    We propose a universal approach for analysis and fast simulations of stiff stochastic biochemical kinetics networks, which rests on elimination of fast chemical species without a loss of information about mesoscoplc, non-Poissonian fluctuations of the slow ones. Our approach, which is similar to the Born-Oppenhelmer approximation in quantum mechanics, follows from the stochastic path Integral representation of the cumulant generating function of reaction events. In applications with a small number of chemIcal reactions, It produces analytical expressions for cumulants of chemical fluxes between the slow variables. This allows for a low-dimensional, Interpretable representation and can be used for coarse-grained numerical simulation schemes with a small computational complexity and yet high accuracy. As an example, we derive the coarse-grained description for a chain of biochemical reactions, and show that the coarse-grained and the microscopic simulations are in an agreement, but the coarse-gralned simulations are three orders of magnitude faster.

  10. On Coarse Projective Integration for Atomic Deposition in Amorphous Systems

    SciTech Connect

    Chuang, Claire Y.; Han, Sang M.; Zepeda-Ruiz, Luis A.; Sinno, Talid

    2015-10-02

    Direct molecular dynamics simulation of atomic deposition under realistic conditions is notoriously challenging because of the wide range of timescales that must be captured. Numerous simulation approaches have been proposed to address the problem, often requiring a compromise between model fidelity, algorithmic complexity and computational efficiency. Coarse projective integration, an example application of the ‘equation-free’ framework, offers an attractive balance between these constraints. Here, periodically applied, short atomistic simulations are employed to compute gradients of slowly-evolving coarse variables that are then used to numerically integrate differential equations over relatively large time intervals. A key obstacle to the application of this technique in realistic settings is the ‘lifting’ operation in which a valid atomistic configuration is recreated from knowledge of the coarse variables. Using Ge deposition on amorphous SiO2 substrates as an example application, we present a scheme for lifting realistic atomistic configurations comprised of collections of Ge islands on amorphous SiO2 using only a few measures of the island size distribution. In conclusion, the approach is shown to provide accurate initial configurations to restart molecular dynamics simulations at arbitrary points in time, enabling the application of coarse projective integration for this morphologically complex system.

  11. On Coarse Projective Integration for Atomic Deposition in Amorphous Systems

    DOE PAGES

    Chuang, Claire Y.; Han, Sang M.; Zepeda-Ruiz, Luis A.; ...

    2015-10-02

    Direct molecular dynamics simulation of atomic deposition under realistic conditions is notoriously challenging because of the wide range of timescales that must be captured. Numerous simulation approaches have been proposed to address the problem, often requiring a compromise between model fidelity, algorithmic complexity and computational efficiency. Coarse projective integration, an example application of the ‘equation-free’ framework, offers an attractive balance between these constraints. Here, periodically applied, short atomistic simulations are employed to compute gradients of slowly-evolving coarse variables that are then used to numerically integrate differential equations over relatively large time intervals. A key obstacle to the application of thismore » technique in realistic settings is the ‘lifting’ operation in which a valid atomistic configuration is recreated from knowledge of the coarse variables. Using Ge deposition on amorphous SiO2 substrates as an example application, we present a scheme for lifting realistic atomistic configurations comprised of collections of Ge islands on amorphous SiO2 using only a few measures of the island size distribution. In conclusion, the approach is shown to provide accurate initial configurations to restart molecular dynamics simulations at arbitrary points in time, enabling the application of coarse projective integration for this morphologically complex system.« less

  12. Personal Coarse Particulate Matter Exposures in an Adult Cohort

    EPA Science Inventory

    Volunteers associated with the North Carolina Adult Asthma and Environment Study (NCAAES) participated in an investigation of personal daily exposures to coarse and fine particulate matter size fractions (PM10-2.5, PM2.5). Data from these personal measuremen...

  13. Coarse woody debris in oak woodlands of California.

    Treesearch

    William D. Tietje; Karen L. Waddell; Justin K. Vreeland; Charles L. Bolsinger

    2002-01-01

    An extensive forest inventory was conducted to estimate the amount and distribution of coarse woody debris (CWD) on 5.6 million ac of woodlands in California that are outside of national forests and reserved areas. Woodlands consist primarily of oak (Quercus spp.) types and are defined as forestland incapable of producing commercial quantities of...

  14. Improving coarse woody debris measurements: a taper-based technique

    Treesearch

    Christopher W. Woodall; James A. Westfall

    2007-01-01

    Coarse woody debris (CWD) are dead and down trees of a certain minimum size that are an important forest ecosystem component (e.g., wildlife habitat, carbon stocks, and fuels). Accurately measuring the dimensions of CWD is important for ensuring the quality of CWD estimates and hence for accurately assessing forest ecosystem attributes. To improve the quality of CWD...

  15. On coarse projective integration for atomic deposition in amorphous systems

    SciTech Connect

    Chuang, Claire Y. E-mail: meister@unm.edu Sinno, Talid; Han, Sang M. E-mail: meister@unm.edu; Zepeda-Ruiz, Luis A. E-mail: meister@unm.edu

    2015-10-07

    Direct molecular dynamics simulation of atomic deposition under realistic conditions is notoriously challenging because of the wide range of time scales that must be captured. Numerous simulation approaches have been proposed to address the problem, often requiring a compromise between model fidelity, algorithmic complexity, and computational efficiency. Coarse projective integration, an example application of the “equation-free” framework, offers an attractive balance between these constraints. Here, periodically applied, short atomistic simulations are employed to compute time derivatives of slowly evolving coarse variables that are then used to numerically integrate differential equations over relatively large time intervals. A key obstacle to the application of this technique in realistic settings is the “lifting” operation in which a valid atomistic configuration is recreated from knowledge of the coarse variables. Using Ge deposition on amorphous SiO{sub 2} substrates as an example application, we present a scheme for lifting realistic atomistic configurations comprised of collections of Ge islands on amorphous SiO{sub 2} using only a few measures of the island size distribution. The approach is shown to provide accurate initial configurations to restart molecular dynamics simulations at arbitrary points in time, enabling the application of coarse projective integration for this morphologically complex system.

  16. Coarse-Grained and Atomistic Modeling of Polyimides

    NASA Technical Reports Server (NTRS)

    Clancy, Thomas C.; Hinkley, Jeffrey A.

    2004-01-01

    A coarse-grained model for a set of three polyimide isomers is developed. Each polyimide is comprised of BPDA (3,3,4,4' - biphenyltetracarboxylic dianhydride) and one of three APB isomers: 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene or 1,3-bis(3-aminophenoxy)benzene. The coarse-grained model is constructed as a series of linked vectors following the contour of the polymer backbone. Beads located at the midpoint of each vector define centers for long range interaction energy between monomer subunits. A bulk simulation of each coarse-grained polyimide model is performed with a dynamic Monte Carlo procedure. These coarsegrained models are then reverse-mapped to fully atomistic models. The coarse-grained models show the expected trends in decreasing chain dimensions with increasing meta linkage in the APB section of the repeat unit, although these differences were minor due to the relatively short chains simulated here. Considerable differences are seen among the dynamic Monte Carlo properties of the three polyimide isomers. Decreasing relaxation times are seen with increasing meta linkage in the APB section of the repeat unit.

  17. 7. DETAIL OF ROOM BELOW GRIZZLY SHOWING BOTTOM OF COARSE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. DETAIL OF ROOM BELOW GRIZZLY SHOWING BOTTOM OF COARSE ORE BIN AND CHUTE TO BEGINNING OF CONVEYOR BELT, SOUTH VIEW. - Vanadium Corporation of America (VCA) Naturita Mill, Sampling Building & Ore Receiving Platform, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

  18. Exploration of scaling effects on coarse resolution land surface phenology

    USDA-ARS?s Scientific Manuscript database

    A great number of land surface phenoloy (LSP) data have been produced from various coarse resolution satellite datasets and detection algorithms across regional and global scales. Unlike field- measured phenological events which are quantitatively defined with clear biophysical meaning, current LSP ...

  19. A coarse wood dynamics model for the Western Cascades.

    Treesearch

    K. Mellen; A. Ager

    2002-01-01

    The Coarse Wood Dynamics Model (CWDM) analyzes the dynamics (fall, fragmentation, and decomposition) of Douglas-fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla) snags and down logs in forested ecosystems of the western Cascades of Oregon and Washington. The model predicts snag fall, height loss and decay,...

  20. A distance limited method for sampling downed coarse woody debris

    Treesearch

    Jeffrey H. Gove; Mark J. Ducey; Harry T. Valentine; Michael S. Williams

    2012-01-01

    A new sampling method for down coarse woody debris is proposed based on limiting the perpendicular distance from individual pieces to a randomly chosen sample point. Two approaches are presented that allow different protocols to be used to determine field measurements; estimators for each protocol are also developed. Both protocols are compared via simulation against...

  1. Terrain aided navigation for autonomous underwater vehicles with coarse maps

    NASA Astrophysics Data System (ADS)

    Zhou, Ling; Cheng, Xianghong; Zhu, Yixian

    2016-09-01

    Terrain aided navigation (TAN) is a form of geophysical localization technique for autonomous underwater vehicles (AUVs) operating in GPS-denied environments. TAN performance on sensor-rich AUVs has been evaluated in sea trials. However, many challenges remain before TAN can be successfully implemented on sensor-limited AUVs, especially with coarse maps. To improve TAN performance over coarse maps, a Gaussian process (GP) is proposed for the modeling of bathymetric terrain and integrated into the particle filter (GP-PF). GP is applied to provide not only the bathymetric value prediction through learning a set of bathymetric data from coarse maps but also the variance of the prediction. As a measurement update, calculated on bathymetric deviation is performed through the PF to obtain absolute and bounded positioning accuracy. Through the analysis of TAN performance on experimental data for two different terrains with map resolutions of 10-50 m, both the ability of the proposed model to represent the actual bathymetric terrain with accuracy and the effect of the GP-PF for TAN on sensor-limited systems in suited terrain are demonstrated. The experiment results further verify that there is an inverse relationship between the coarseness of the map and the overall TAN accuracy in rough terrains, but there is hardly any relationship between them in relatively flat terrains.

  2. Evaluation of a Direct Personal Coarse Particulate Matter Monitor

    EPA Science Inventory

    One aspect of the North Carolina Adult Asthma and Environment study (NCAAES) was to evaluate personal exposures to coarse particulate matter (PM 10-2.5) and their associated variability. As part of this, we examined the ability of a community-based monitor to act as...

  3. Personal Coarse Particulate Matter Exposures in an Adult Cohort

    EPA Science Inventory

    Volunteers associated with the North Carolina Adult Asthma and Environment Study (NCAAES) participated in an investigation of personal daily exposures to coarse and fine particulate matter size fractions (PM10-2.5, PM2.5). Data from these personal measuremen...

  4. 7 CFR 457.113 - Coarse grains crop insurance provisions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... years are as follows: United States Department of Agriculture Federal Crop Insurance Corporation Coarse.... The crop defined as sorghum under the United States Grain Standards Act. Harvest. Combining, threshing... under the Official United States Standards for Grain, including but not limited to protein and oil, will...

  5. 7 CFR 457.113 - Coarse grains crop insurance provisions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... years are as follows: United States Department of Agriculture Federal Crop Insurance Corporation Coarse.... The crop defined as sorghum under the United States Grain Standards Act. Harvest. Combining, threshing... under the Official United States Standards for Grain, including but not limited to protein and oil, will...

  6. Atmospheric PAH concentrations in fine and coarse particles.

    PubMed

    Vardar, Nedim; Noll, Kenneth E

    2003-09-01

    Measurements of the urban air concentrations of PAHs associated with PM2.5-fine and PM 10-coarse particles in Chicago on the campus of IIT were achieved using a Universal Air Sampler. Short sampling time (12 hr) and high flow rates were used to measure the PAH concentrations in fine and coarse particles. Measured ambient concentrations of PAHs were classified based on wind direction and back trajectory calculations as Land and Lake samples. Differences in ambient concentrations of PAHs were observed between Land and Lake samples. Fine particle concentrations varied from 9.5 to 25.7 ng m(-3) and averaged 18.2 ng m(-3) for the Land samples, while they ranged from 4.2 to 31.5 ng m(-3) and averaged 13.4 ng m(-3) for the Lake samples. The measured PAH concentrations in coarse particles varied from 6.2 to 22.1 ng m(-3) and averaged 12.9 ng m(-3) for the Land samples, and they ranged from 2.4 to 13.0 ng m(-3) with an average value of 7.3 ng m(-3) for the Lake samples. The fine/coarse ratio of each individual PAH compound varied between 1.3 and 2.7 for the Land samples: it varied between 1.6 and 4.2 for the Lake samples. There was an increase in the fine/coarse ratio of PAH as molecular weight of the compound increases for both Land and Lake samples.

  7. Chemical-mineralogical characterisation of coarse recycled concrete aggregate

    SciTech Connect

    Limbachiya, M.C. . E-mail: m.limbachiya@kingston.ac.uk; Marrocchino, E.; Koulouris, A.

    2007-07-01

    The construction industry is now putting greater emphasis than ever before on increasing recycling and promoting more sustainable waste management practices. In keeping with this approach, many sectors of the industry have actively sought to encourage the use of recycled concrete aggregate (RCA) as an alternative to primary aggregates in concrete production. The results of a laboratory experimental programme aimed at establishing chemical and mineralogical characteristics of coarse RCA and its likely influence on concrete performance are reported in this paper. Commercially produced coarse RCA and natural aggregates (16-4 mm size fraction) were tested. Results of X-ray fluorescence (XRF) analyses showed that original source of RCA had a negligible effect on the major elements and a comparable chemical composition between recycled and natural aggregates. X-ray diffraction (XRD) analyses results indicated the presence of calcite, portlandite and minor peaks of muscovite/illite in recycled aggregates, although they were directly proportioned to their original composition. The influence of 30%, 50%, and 100% coarse RCA on the chemical composition of equal design strength concrete has been established, and its suitability for use in a concrete application has been assessed. In this work, coarse RCA was used as a direct replacement for natural gravel in concrete production. Test results indicated that up to 30% coarse RCA had no effect on the main three oxides (SiO{sub 2}, Al{sub 2}O{sub 3} and CaO) of concrete, but thereafter there was a marginal decrease in SiO{sub 2} and increase in Al{sub 2}O{sub 3} and CaO contents with increase in RCA content in the mix, reflecting the original constituent's composition.

  8. Chemical-mineralogical characterisation of coarse recycled concrete aggregate.

    PubMed

    Limbachiya, M C; Marrocchino, E; Koulouris, A

    2007-01-01

    The construction industry is now putting greater emphasis than ever before on increasing recycling and promoting more sustainable waste management practices. In keeping with this approach, many sectors of the industry have actively sought to encourage the use of recycled concrete aggregate (RCA) as an alternative to primary aggregates in concrete production. The results of a laboratory experimental programme aimed at establishing chemical and mineralogical characteristics of coarse RCA and its likely influence on concrete performance are reported in this paper. Commercially produced coarse RCA and natural aggregates (16-4 mm size fraction) were tested. Results of X-ray fluorescence (XRF) analyses showed that original source of RCA had a negligible effect on the major elements and a comparable chemical composition between recycled and natural aggregates. X-ray diffraction (XRD) analyses results indicated the presence of calcite, portlandite and minor peaks of muscovite/illite in recycled aggregates, although they were directly proportioned to their original composition. The influence of 30%, 50%, and 100% coarse RCA on the chemical composition of equal design strength concrete has been established, and its suitability for use in a concrete application has been assessed. In this work, coarse RCA was used as a direct replacement for natural gravel in concrete production. Test results indicated that up to 30% coarse RCA had no effect on the main three oxides (SiO2, Al2O3 and CaO) of concrete, but thereafter there was a marginal decrease in SiO2 and increase in Al2O3 and CaO contents with increase in RCA content in the mix, reflecting the original constituent's composition.

  9. Fiber-optic evanescent-field laser sensor for in-situ gas diagnostics.

    PubMed

    Willer, Ulrike; Scheel, Dirk; Kostjucenko, Irina; Bohling, Christian; Schade, Wolfgang; Faber, Eckhard

    2002-09-01

    A compact, rugged and portable fiber-optic evanescent-field laser sensor is developed for the detection of gaseous species in harsh environments such as volcano fumaroles or industrial combustion of glass furnaces. The sensor consists of an optical multi-mode fused silica fiber with jacket and cladding removed and the bare fiber core in direct contact with the surrounding molecules. The beam of a single-mode DFB diode laser with an emission wavelength centered at 1.5705 microm is coupled into the fiber. At the other end of the fiber an infrared detector is used to record the transmitted infrared laser light intensity. Due to the frustrated total reflection (FTR) and the attenuated total reflection (ATR) the laser intensity is attenuated when passing through the fiber. The FTR is related to a change of the index of refraction while the latter one is related to a change of the absorption coefficient. While tuning the DFB laser wavelength across absorption lines of molecules surrounding the fiber a spectral intensity profile is measured. Voigt functions are fitted to the recorded intensity profiles to estimate relative molecule concentrations. In this paper results from first field measurements at the volcano site 'Solfatara' in Italy are reported that use such a sensor device for simultaneous detection of H2S, CO2 and H2O directly in the gas stream of a volcano fumarole.

  10. Simultaneous observations of electromagnetically induced transparency (EIT) and absorption (EIA) in a multi-level V-type system of 87Rb and theoretical simulation of the observed spectra using a multi-mode approach

    NASA Astrophysics Data System (ADS)

    Das, Bankim Chandra; Bhattacharyya, Dipankar; Das, Arpita; Chakrabarti, Shrabana; De, Sankar

    2016-12-01

    We report here simultaneous experimental observation of Electromagnetically Induced Transparency (EIT) and Electromagnetically Induced Absorption (EIA) in a multi-level V-type system in D2 transition of 87Rb, i.e., F =2 →F' with a strong pump and a weak probe beam. We studied the probe spectrum by locking the probe beam to the transition F =2 →F'=2 while the pump is scanned from F =2 →F' . EIA is observed for the open transition (F =2 →F'=2 ) whereas EIT is observed in the closed transition (F =2 →F'=3 ). Sub natural line-width is observed for the EIA. To simulate the observed spectra theoretically, Liouville equation for the three-level V-type system is solved analytically with a multi-mode approach for the density matrix elements. We assumed both the pump and the probe beams can couple the excited states. A multi-mode approach for the coherence terms facilitates the study of all the frequency contributions due to the pump and the probe fields. Since the terms contain higher harmonics of the pump and the probe frequencies, we expressed them in Fourier transformed forms. To simulate the probe spectrum, we have solved inhomogeneous difference equations for the coherence terms using the Green's function technique and continued fraction theory. The experimental line-widths of the EIT and the EIA are compared with our theoretical model. Our system can be useful in optical switching applications as it can be precisely tuned to render the medium opaque and transparent simultaneously.

  11. Two Fiber Optical Fiber Thermometry

    NASA Technical Reports Server (NTRS)

    Jones, Mathew R.; Farmer, Jeffery T.; Breeding, Shawn P.

    2000-01-01

    An optical fiber thermometer consists of an optical fiber whose sensing tip is given a metallic coating. The sensing tip of the fiber is essentially an isothermal cavity, so the emission from this cavity will be approximately equal to the emission from a blackbody. Temperature readings are obtained by measuring the spectral radiative heat flux at the end of the fiber at two wavelengths. The ratio of these measurements and Planck's Law are used to infer the temperature at the sensing tip. Optical fiber thermometers have high accuracy, excellent long-term stability and are immune to electromagnetic interference. In addition, they can be operated for extended periods without requiring re-calibration. For these reasons. it is desirable to use optical fiber thermometers in environments such as the International Space Station. However, it has recently been shown that temperature readings are corrupted by emission from the fiber when extended portions of the probe are exposed to elevated temperatures. This paper will describe several ways in which the reading from a second fiber can be used to correct the corrupted temperature measurements. The accuracy and sensitivity to measurement uncertainty will be presented for each method.

  12. Two Fiber Optical Fiber Thermometry

    NASA Technical Reports Server (NTRS)

    Jones, Mathew R.; Farmer, Jeffery T.; Breeding, Shawn P.

    2000-01-01

    An optical fiber thermometer consists of an optical fiber whose sensing tip is given a metallic coating. The sensing tip of the fiber is essentially an isothermal cavity, so the emission from this cavity will be approximately equal to the emission from a blackbody. Temperature readings are obtained by measuring the spectral radiative heat flux at the end of the fiber at two wavelengths. The ratio of these measurements and Planck's Law are used to infer the temperature at the sensing tip. Optical fiber thermometers have high accuracy, excellent long-term stability and are immune to electromagnetic interference. In addition, they can be operated for extended periods without requiring re-calibration. For these reasons. it is desirable to use optical fiber thermometers in environments such as the International Space Station. However, it has recently been shown that temperature readings are corrupted by emission from the fiber when extended portions of the probe are exposed to elevated temperatures. This paper will describe several ways in which the reading from a second fiber can be used to correct the corrupted temperature measurements. The accuracy and sensitivity to measurement uncertainty will be presented for each method.

  13. From Cooperative Self-Assembly to Water-Soluble Supramolecular Polymers Using Coarse-Grained Simulations.

    PubMed

    Bochicchio, Davide; Pavan, Giovanni M

    2017-01-24

    Supramolecular polymers, formed via noncovalent self-assembly of elementary monomers, are extremely interesting for their dynamic bioinspired properties. In order to understand their behavior, it is necessary to access their dynamics while maintaining high resolution in the treatment of the monomer structure and monomer-monomer interactions, which is typically a difficult task, especially in aqueous solution. Focusing on 1,3,5-benzenetricarboxamide (BTA) water-soluble supramolecular polymers, we have developed a transferable coarse-grained model that allows studying BTA supramolecular polymerization in water, while preserving remarkable consistency with the atomistic models in the description of the key interactions between the monomers (hydrophobic, H-bonding, etc.), self-assembly cooperativity, and amplification of order into the growing fibers. This permitted us to monitor the amplification of the key interactions between the monomers (including H-bonding) in the BTA fibers during the dynamic polymerization process. Our molecular dynamics simulations provide a picture of a stepwise cooperative polymerization mechanism, where initial fast hydrophobic aggregation of the BTA monomers in water is followed by the slower reorganization of these disordered aggregates into ordered directional oligomers. Supramolecular polymer growth then proceeds on a slower time scale. We challenged our models via comparison with the experimental evidence, capturing the effect of temperature variations and subtle changes in the monomer structure on the polymerization and on the properties of the fibers seen in the real systems. This work provides a multiscale spatiotemporal characterization of BTA self-assembly in water and a useful platform to study a variety of BTA-based supramolecular polymers toward structure-property relationships.

  14. Optical Fibers

    NASA Astrophysics Data System (ADS)

    Ghatak, Ajoy; Thyagarajan, K.

    With the development of extremely low-loss optical fibers and their application to communication systems, a revolution has taken fiber glass place during the last 40 years. In 2001, using glass fibers as the transmission medium and lightwaves as carrier wave waves, information was transmitted at a rate more than 1 Tbit/s (which is roughly equivalent to transmission of about 15 million simultaneous telephone conversations) through one hair thin optical fiber. Experimental demonstration of transmission at the rate of 14 Tbit/s over a 160 km long single fiber was demonstrated in 2006, which is equivalent to sending 140 digital high definition movies in 1 s. Very recently record transmission of more than 100 Tbit/s over 165 km single mode fiber has been reported. These can be considered as extremely important technological achievements. In this chapter we will discuss the propagation characteristics of optical fibers with special applications to optical communication systems and also present some of the noncommunication applications such as sensing.

  15. Vacuum fiber-fiber coupler

    NASA Astrophysics Data System (ADS)

    Heinrici, Axel; Bjelajac, Goran; Jonkers, Jeroen; Jakobs, Stefan; Olschok, Simon; Reisgen, Uwe

    2017-02-01

    Research and development carried out by the ISF Welding and Joining Institute of RWTH Aachen University has proven that combining high power laser and low vacuum atmosphere provides a welding performance and quality, which is comparable to electron beam welding. The developed welding machines are still using a beam forming which takes place outside the vacuum and the focusing laser beam has to be introduced to the vacuum via a suitable window. This inflexible design spoils much of the flexibility of modern laser welding. With the target to bring a compact, lightweight flying optics with flexible laser transport fibers into vacuum chambers, a high power fiber-fiber coupler has been adapted by II-VI HIGHYAG that includes a reliable vacuum interface. The vacuum-fiber-fiber coupler (V-FFC) is tested with up to 16 kW sustained laser power and the design is flexible in terms of a wide variety of laser fiber plug systems and vacuum flanges. All that is needed to implement the V-FFC towards an existing or planned vacuum chamber is an aperture of at least 100 mm (4 inch) diameter with any type of vacuum or pressure flange. The V-FFC has a state-of-the-art safety interface which allows for fast fiber breakage detection for both fibers (as supported by fibers) by electric wire breakage and short circuit detection. Moreover, the System also provides connectors for cooling and electric signals for the laser beam optics inside the vacuum. The V-FFC has all necessary adjustment options for coupling the laser radiation to the receiving fiber.

  16. Highly sensitive curvature sensor based on long period fiber grating with alternately splicing multiple single/multimode structure

    NASA Astrophysics Data System (ADS)

    Hu, Qihao; Zhang, Shuo; Yang, Wenlei; Geng, Tao; Sun, Weimin; Sun, Cuiting; Jin, Xiren; Yuan, Libo

    2017-09-01

    A highly sensitive curvature sensor made of a novel long period fiber grating (LPFG) is presented and experimentally demonstrated. It is constructed by splicing multiple single mode fibers (SMFs) and multi-mode fibers (MMFs) alternately (MS/MA). The measurement result shows that it has a high sensitivity of -22.4 nm/m-1 in the range from 0.223 m-1 to 4.358 m-1. It can measure curvature on all direction due to the symmetric structure. The proposed sensor was also insensitive to the temperature, whose temperature sensitivity was around -0.015 nm/°C in the range from 40 °C to 200 °C. The advantages of high curvature sensitivity and low temperature sensitivity make it has a great potential to measure curvature in practical application with high resolutions.

  17. Fireblocking Fibers

    NASA Technical Reports Server (NTRS)

    1986-01-01

    PBI was originally developed for space suits. In 1980, the need for an alternative to asbestos and stricter government anti-pollution standards led to commercialization of the fire blocking fiber. PBI is used for auto racing driver suits and aircraft seat covers. The fiber does not burn in air, is durable and easily maintained. It has been specified by a number of airliners and is manufactured by Hoechst-Celanese Corporation.

  18. Nanocomposite Fibers

    DTIC Science & Technology

    2003-01-01

    attempts to prepare carbon nanotube , CNT, containing fiber material. Modulus and tenacity tests on experimentally prepared nanosilica filled PET...individual entities of nanofibers, such as carbon nanotubes and SiC whiskers, silica and clay, into polymers with the goal of producing new forms of...if carbon nanotube (CNT) particle implanted fibers are used, one would expect a great increase in the electrical conductivity of the so-reinforced

  19. Dietary fiber.

    PubMed

    Madar, Z; Thorne, R

    1987-01-01

    Studies done on dietary fiber (DF) over the past five years are presented in this Review. The involvement of dietary fiber in the control of plasma glucose and lipid levels is now established. Two dietary fiber sources (soybean and fenugreek) were studied in our laboratory and are discussed herein. These sources were found to be potentially beneficial in the reduction of plasma glucose in non-insulin dependent diabetes mellitus subjects. They are shown to be acceptable by human subjects and are easy to use either in a mixture of milk products and in cooking. The mechanism by which dietary fiber alters the nutrient absorption is also discussed. The effect of DF on gastric emptying, transit time, adsorption and glucose transport may contribute to reducing plasma glucose and lipid levels. DF was found to be effective in controlling blood glucose and lipid levels of pregnant diabetic women. Dietary fiber may also be potentially beneficial in the reduction of exogenous insulin requirements in these subjects. However, increased consumption of DF may cause adverse side effects; the binding capabilities of fiber may affect nutrient availability, particularly that of minerals and prolonged and high DF dosage supplementation must be regarded cautiously. This is particularly true when recommending such a diet for pregnant or lactating women, children or subjects with nutritional disorders. Physiological effects of DF appear to depend heavily on the source and composition of fiber. Using a combination of DF from a variety of sources may reduce the actual mass of fiber required to obtain the desired metabolic effects and will result in a more palatable diet. Previously observed problems, such as excess flatus, diarrhea and mineral malabsorption would also be minimized.

  20. Linear mixing model applied to coarse resolution satellite data

    NASA Technical Reports Server (NTRS)

    Holben, Brent N.; Shimabukuro, Yosio E.

    1992-01-01

    A linear mixing model typically applied to high resolution data such as Airborne Visible/Infrared Imaging Spectrometer, Thematic Mapper, and Multispectral Scanner System is applied to the NOAA Advanced Very High Resolution Radiometer coarse resolution satellite data. The reflective portion extracted from the middle IR channel 3 (3.55 - 3.93 microns) is used with channels 1 (0.58 - 0.68 microns) and 2 (0.725 - 1.1 microns) to run the Constrained Least Squares model to generate fraction images for an area in the west central region of Brazil. The derived fraction images are compared with an unsupervised classification and the fraction images derived from Landsat TM data acquired in the same day. In addition, the relationship betweeen these fraction images and the well known NDVI images are presented. The results show the great potential of the unmixing techniques for applying to coarse resolution data for global studies.

  1. Crowding with detection and coarse discrimination of simple visual features.

    PubMed

    Põder, Endel

    2008-04-24

    Some recent studies have suggested that there are actually no crowding effects with detection and coarse discrimination of simple visual features. The present study tests the generality of this idea. A target Gabor patch, surrounded by either 2 or 6 flanker Gabors, was presented briefly at 4 deg eccentricity of the visual field. Each Gabor patch was oriented either vertically or horizontally (selected randomly). Observers' task was either to detect the presence of the target (presented with probability 0.5) or to identify the orientation of the target. The target-flanker distance was varied. Results were similar for the two tasks but different for 2 and 6 flankers. The idea that feature detection and coarse discrimination are immune to crowding may be valid for the two-flanker condition only. With six flankers, a normal crowding effect was observed. It is suggested that the complexity of the full pattern (target plus flankers) could explain the difference.

  2. Coarse-Graining in Simulations of Multicomponent Polymer Systems

    NASA Astrophysics Data System (ADS)

    Sethuraman, Vaidyanathan; Ganesan, Venkat

    2015-03-01

    We investigate the mapping required between the interaction parameters of two different coarse-grained simulation models to ensure a match of the long-range structural characteristics of multicomponent polymeric system. We investigate the extensibility of mapping functions deduced in the context of symmetric block copolymers by Morse and coworkers to other polymeric systems by studying a variety of systems, including, asymmetric diblock copolymers, symmetric triblock copolymers and diblock copolymer-solvent mixtures. We observe excellent agreement for peak in the inverse structure between two popular coarse grained models for all sets of polymeric melt systems investigated, thus showing that the mapping function proposed for diblock copolymer melts is transferable to other polymer melts irrespective of the blockiness or overall composition. We use our findings to propose a methodology to create ordered morphologies in simulations involving hard repulsive potentials in a computationally efficient manner.

  3. A nucleotide-level coarse-grained model of RNA

    SciTech Connect

    Šulc, Petr; Ouldridge, Thomas E.; Louis, Ard A.; Romano, Flavio; Doye, Jonathan P. K.

    2014-06-21

    We present a new, nucleotide-level model for RNA, oxRNA, based on the coarse-graining methodology recently developed for the oxDNA model of DNA. The model is designed to reproduce structural, mechanical, and thermodynamic properties of RNA, and the coarse-graining level aims to retain the relevant physics for RNA hybridization and the structure of single- and double-stranded RNA. In order to explore its strengths and weaknesses, we test the model in a range of nanotechnological and biological settings. Applications explored include the folding thermodynamics of a pseudoknot, the formation of a kissing loop complex, the structure of a hexagonal RNA nanoring, and the unzipping of a hairpin motif. We argue that the model can be used for efficient simulations of the structure of systems with thousands of base pairs, and for the assembly of systems of up to hundreds of base pairs. The source code implementing the model is released for public use.

  4. Recent Advances in Transferable Coarse-Grained Modeling of Proteins

    PubMed Central

    Kar, Parimal; Feig, Michael

    2017-01-01

    Computer simulations are indispensable tools for studying the structure and dynamics of biological macromolecules. Biochemical processes occur on different scales of length and time. Atomistic simulations cannot cover the relevant spatiotemporal scales at which the cellular processes occur. To address this challenge, coarse-grained (CG) modeling of the biological systems are employed. Over the last few years, many CG models for proteins continue to be developed. However, many of them are not transferable with respect to different systems and different environments. In this review, we discuss those CG protein models that are transferable and that retain chemical specificity. We restrict ourselves to CG models of soluble proteins only. We also briefly review recent progress made in the multi-scale hybrid all-atom/coarse-grained simulations of proteins. PMID:25443957

  5. Has coarse ocean resolution biased simulations of transient climate sensitivity?

    NASA Astrophysics Data System (ADS)

    Winton, Michael; Anderson, Whit G.; Delworth, Thomas L.; Griffies, Stephen M.; Hurlin, William J.; Rosati, Anthony

    2014-12-01

    We investigate the influence of ocean component resolution on simulation of climate sensitivity using variants of the GFDL CM2.5 climate model incorporating eddy-resolving (1/10°) and eddy-parameterizing (1°) ocean resolutions. Two parameterization configurations of the coarse-resolution model are used yielding a three-model suite with significant variation in the transient climate response (TCR). The variation of TCR in this suite and in an enhanced group of 10 GFDL models is found to be strongly associated with the control climate Atlantic meridional overturning circulation (AMOC) magnitude and its decline under forcing. We find that it is the AMOC behavior rather than resolution per se that accounts for most of the TCR differences. A smaller difference in TCR stems from the eddy-resolving model having more Southern Ocean surface warming than the coarse models.

  6. Salient object detection using coarse-to-fine processing.

    PubMed

    Zhou, Qiangqiang; Zhang, Lin; Zhao, Weidong; Liu, Xianhui; Chen, Yufei; Wang, Zhicheng

    2017-03-01

    In this paper, we propose a salient object detection algorithm that considers both background and foreground cues. It integrates both coarse salient region extraction and a top-down background weight map measure via boundary label propagation into a unified optimization framework to acquire a refined salient map. The coarse saliency map is additionally fused by three prior components: a local contrast map with greater alignment to physiological law, a global focus prior map, and a global color prior map. During the formation of the background weight map, we first construct an affinity matrix and select nodes existing on the border as labels to represent the background. Then we perform a propagation to generate the regional background weight map. Our proposed model was verified on four benchmark datasets, and the experimental results demonstrate that our method has excellent performance.

  7. Coarse pointing mechanism assembly for satellite interlink experiment

    NASA Technical Reports Server (NTRS)

    Maeusli, P. A.; Ivorra, M. T.; Gass, V.; Berthoud, J. F.

    1996-01-01

    Since 1975, MECANEX S.A. has been manufacturing components for solar array drives and mechanisms used in space applications. In 1991, work was started in an early phase C (Engineering Model) on a Coarse Pointing Mechanism Assembly (CPMA) for the Semiconductor-laser Inter-satellite Link EXperiment (SILEX). This paper deals with the history, the evolution, and the lessons learned from taking over a pre-design in 1991 to the delivery of last flight models (FM 5 & 6) in 1995.

  8. Enhancing physiologic simulations using supervised learning on coarse mesh solutions

    PubMed Central

    Kolandaivelu, Kumaran; O'Brien, Caroline C.; Shazly, Tarek; Edelman, Elazer R.; Kolachalama, Vijaya B.

    2015-01-01

    Computational modelling of physical and biochemical processes has emerged as a means of evaluating medical devices, offering new insights that explain current performance, inform future designs and even enable personalized use. Yet resource limitations force one to compromise with reduced order computational models and idealized assumptions that yield either qualitative descriptions or approximate, quantitative solutions to problems of interest. Considering endovascular drug delivery as an exemplary scenario, we used a supervised machine learning framework to process data generated from low fidelity coarse meshes and predict high fidelity solutions on refined mesh configurations. We considered two models simulating drug delivery to the arterial wall: (i) two-dimensional drug-coated balloons and (ii) three-dimensional drug-eluting stents. Simulations were performed on computational mesh configurations of increasing density. Supervised learners based on Gaussian process modelling were constructed from combinations of coarse mesh setting solutions of drug concentrations and nearest neighbourhood distance information as inputs, and higher fidelity mesh solutions as outputs. These learners were then used as computationally inexpensive surrogates to extend predictions using low fidelity information to higher levels of mesh refinement. The cross-validated, supervised learner-based predictions improved fidelity as compared with computational simulations performed at coarse level meshes—a result consistent across all outputs and computational models considered. Supervised learning on coarse mesh solutions can augment traditional physics-based modelling of complex physiologic phenomena. By obtaining efficient solutions at a fraction of the computational cost, this framework has the potential to transform how modelling approaches can be applied in the evaluation of medical technologies and their real-time administration in an increasingly personalized fashion. PMID:25652458

  9. Coarse-graining in simulations of multicomponent polymer systems

    NASA Astrophysics Data System (ADS)

    Sethuraman, Vaidyanathan; Nguyen, Bryan H.; Ganesan, Venkat

    2014-12-01

    We investigate the mapping required between the interaction parameters of two different coarse-grained simulation models to ensure a match of the long-range structural characteristics of multicomponent polymeric system. The basis for our studies is the recent work of Morse and workers, which demonstrated the existence of a mapping between the interaction parameters of different coarse-grained simulation models which allow for a matching of the peak of the disordered state structure factor in symmetric diblock copolymers. We investigate the extensibility of their results to other polymeric systems by studying a variety of systems, including, asymmetric diblock copolymers, symmetric triblock copolymers, and diblock copolymer-solvent mixtures. By using the mapping deduced in the context of symmetric diblock copolymers, we observe excellent agreement for peak in the inverse structure between both two popular coarse grained models for all sets of polymeric melt systems investigated, thus showing that the mapping function proposed for diblock copolymer melts is transferable to other polymer melts irrespective of the blockiness or overall composition. Interestingly, for the limited parameter range of polymer-solvent systems investigated in this article, the mapping functions developed for polymer melts are shown to be equally effective in mapping the structure factor of the coarse-grained simulation models. We use our findings to propose a methodology to create ordered morphologies in simulations involving hard repulsive potentials in a computationally efficient manner. We demonstrate the outcomes of methodology by creating lamellar and cylindrical phases of diblock copolymers of long chains in the popularly used Kremer-Grest simulation model.

  10. Enhancing physiologic simulations using supervised learning on coarse mesh solutions.

    PubMed

    Kolandaivelu, Kumaran; O'Brien, Caroline C; Shazly, Tarek; Edelman, Elazer R; Kolachalama, Vijaya B

    2015-03-06

    Computational modelling of physical and biochemical processes has emerged as a means of evaluating medical devices, offering new insights that explain current performance, inform future designs and even enable personalized use. Yet resource limitations force one to compromise with reduced order computational models and idealized assumptions that yield either qualitative descriptions or approximate, quantitative solutions to problems of interest. Considering endovascular drug delivery as an exemplary scenario, we used a supervised machine learning framework to process data generated from low fidelity coarse meshes and predict high fidelity solutions on refined mesh configurations. We considered two models simulating drug delivery to the arterial wall: (i) two-dimensional drug-coated balloons and (ii) three-dimensional drug-eluting stents. Simulations were performed on computational mesh configurations of increasing density. Supervised learners based on Gaussian process modelling were constructed from combinations of coarse mesh setting solutions of drug concentrations and nearest neighbourhood distance information as inputs, and higher fidelity mesh solutions as outputs. These learners were then used as computationally inexpensive surrogates to extend predictions using low fidelity information to higher levels of mesh refinement. The cross-validated, supervised learner-based predictions improved fidelity as compared with computational simulations performed at coarse level meshes--a result consistent across all outputs and computational models considered. Supervised learning on coarse mesh solutions can augment traditional physics-based modelling of complex physiologic phenomena. By obtaining efficient solutions at a fraction of the computational cost, this framework has the potential to transform how modelling approaches can be applied in the evaluation of medical technologies and their real-time administration in an increasingly personalized fashion.

  11. Coarse-Grained Molecular Dynamics: Dissipation Due to Internal Modes

    SciTech Connect

    Rudd, R E

    2001-12-21

    We describe progress on the issue of pathological elastic wave reflection in atomistic and multiscale simulation. First we briefly review Coarse-Grained Molecular Dynamics (CGMD). Originally CGMD was formulated as a Hamiltonian system in which energy is conserved. This formulation is useful for many applications, but recently CGMD has been extended to include generalized Langevin forces. Here we describe how Langevin dynamics arise naturally in CGMD, and we examine the implication for elastic wave scattering.

  12. Coarse-grained incompressible magnetohydrodynamics: Analyzing the turbulent cascades

    DOE PAGES

    Aluie, Hussein

    2017-02-21

    Here, we formulate a coarse-graining approach to the dynamics of magnetohydrodynamic (MHD) fluids at a continuum of length-scales. In this methodology, effective equations are derived for the observable velocity and magnetic fields spatially-averaged at an arbitrary scale of resolution. The microscopic equations for the bare velocity and magnetic fields are renormalized by coarse-graining to yield macroscopic effective equations that contain both a subscale stress and a subscale electromotive force (EMF) generated by nonlinear interaction of eliminated fields and plasma motions. At large coarse-graining length-scales, the direct dissipation of invariants by microscopic mechanisms (such as molecular viscosity and Spitzer resistivity) ismore » shown to be negligible. The balance at large scales is dominated instead by the subscale nonlinear terms, which can transfer invariants across scales, and are interpreted in terms of work concepts for energy and in terms of topological flux-linkage for the two helicities. An important application of this approach is to MHD turbulence, where the coarse-graining length ℓ lies in the inertial cascade range. We show that in the case of sufficiently rough velocity and/or magnetic fields, the nonlinear inter-scale transfer need not vanish and can persist to arbitrarily small scales. Although closed expressions are not available for subscale stress and subscale EMF, we derive rigorous upper bounds on the effective dissipation they produce in terms of scaling exponents of the velocity and magnetic fields. These bounds provide exact constraints on phenomenological theories of MHD turbulence in order to allow the nonlinear cascade of energy and cross-helicity. On the other hand, we show that the forward cascade of magnetic helicity to asymptotically small scales is impossible unless 3rd-order moments of either velocity or magnetic field become infinite.« less

  13. Coarse semiempirical solution to the protein folding problem

    NASA Astrophysics Data System (ADS)

    Fernández, Ariel; Colubri, Andrés; Appignanesi, Gustavo; Burastero, Teresita

    2001-04-01

    We introduce a semiempirical theory leading to the ab initio prediction of conducive folding pathways and coarsely resolved native backbone geometries of proteins suddenly exposed to in vitro renaturation conditions. The underlying model incorporates a discrete codification of local steric hindrances of the peptide backbone. We first determine a time-evolving finite set of local torsional constraints upon which large-scale organization is built. Thus, the torsional state of the chain is topologically represented by viewing the ( Φ, Ψ)-state of each residue modulo the basin of attraction to which it belongs in the Ramachandran plot. A grammar to combine such coarsely defined torsional states (topologies) and translate them into meaningful patterns of long-range interactions is developed. An algorithm for structure prediction is shown to emerge once this grammar is combined with prescriptions for the time evolution of topological patterns. This algorithm is rooted in the fact that local contributions to the potential energy may be subsumed into time-evolving conformational constraints coarsely defining sets of restricted backbone geometries responsible for framing the patterns of nonbonded interactions. The predictive power of the algorithm is established by obtaining stable topologies of small proteins, which prove to be compatible with their native folds, and computing ab-initio folding pathways for mammalian ubiquitin that ultimately yield a stable structural pattern reproducing its native features.

  14. Moving Beyond Watson-Crick Models of Coarse Grained DNA

    NASA Astrophysics Data System (ADS)

    Dorfman, Kevin; Linak, Margaret; Tourdot, Richard

    2012-02-01

    DNA structure possesses several levels of complexity, ranging from the sequence of bases (primary structure) to base pairing (secondary structure) to its three-dimensional shape (tertiary structure) and can produce a wide variety of conformations in addition to canonical double stranded DNA. By including non-Watson-Crick interactions in a coarse-grained model, we developed a system that not only can capture the traditional B-form double helix, but also can adopt a wide variety of other DNA conformations. In our experimentally parameterized, coarse-grained DNA model we are able to reproduce the microscopic features of double-stranded DNA without the need for explicit constraints and capture experimental melting curves for a number of short DNA hairpins. We demonstrate the utility of the model by simulating more complex tertiary structures such as the folding of the thrombin aptamer, which includes G-quartets, and strand invasion during triplex formation. Our results highlight the importance of non-canonical interactions in DNA coarse- grained models.

  15. Lung response to coarse PM: Bioassay in mice

    SciTech Connect

    Wegesser, Teresa C.; Last, Jerold A.

    2008-07-15

    Particulate matter (PM) elicits inflammatory and toxic responses in the lung specific to its constituents, which can vary by region, time, and particle size. To identify the mechanism of toxicity in PM collected in a rural area in the San Joaquin Valley of Central California, we studied coarse particles of 2.5-10 {mu}m diameter (PM{sub 2.5}-PM{sub 10}). Potential pro-inflammatory and toxic effects of PM{sub 2.5}-PM{sub 10} in the lung were investigated using intratracheally instilled mice. We determined total and differential cell profiles and inflammatory chemokines in lung lavage fluid, and biomarkers of toxicity resulting from coarse PM exposure. Responses of the mice were readily observed with total doses of 25-50 {mu}g of PM per mouse. Changes in pro-inflammatory cellular profiles and chemokines showed both dose and time responses; peak responses were observed 24 h after PM instillation, with recovery as early as 48 h. Furthermore, macrophage inflammatory protein (MIP-2) profiles following PM exposures were correlated to levels of measured macrophages and neutrophils recovered from lung lavage fluid of PM-treated animals. Our data suggest that pro-inflammatory effects observed from coarse PM collected during the summer months from California's hot and dry Central Valley are driven largely by the insoluble components of the PM mixture, and are not caused by endotoxin.

  16. High capacitance of coarse-grained carbide derived carbon electrodes

    DOE PAGES

    Dyatkin, Boris; Gogotsi, Oleksiy; Malinovskiy, Bohdan; ...

    2016-01-01

    Here, we report exceptional electrochemical properties of supercapacitor electrodes composed of large, granular carbide-derived carbon (CDC) particles. We synthesized 70–250 μm sized particles with high surface area and a narrow pore size distribution, using a titanium carbide (TiC) precursor. Electrochemical cycling of these coarse-grained powders defied conventional wisdom that a small particle size is strictly required for supercapacitor electrodes and allowed high charge storage densities, rapid transport, and good rate handling ability. Moreover, the material showcased capacitance above 100 F g-1 at sweep rates as high as 250 mV s-1 in organic electrolyte. 250–1000 micron thick dense CDC films withmore » up to 80 mg cm-2 loading showed superior areal capacitances. The material significantly outperformed its activated carbon counterpart in organic electrolytes and ionic liquids. Furthermore, large internal/external surface ratio of coarse-grained carbons allowed the resulting electrodes to maintain high electrochemical stability up to 3.1 V in ionic liquid electrolyte. In addition to presenting novel insights into the electrosorption process, these coarse-grained carbons offer a pathway to low-cost, high-performance implementation of supercapacitors in automotive and grid-storage applications.« less

  17. Resuspension of coarse fuel hot particles in the Chernobyl area.

    PubMed

    Wagenpfeil, F; Tschiersch, J

    2001-01-01

    Measurements of resuspended aerosol in the Chernobyl 30-km exclusion zone have shown coarse fuel hot particles in the activity range 1-12 Bq 137Cs per particle. The particles were sampled with newly designed rotating arm impactors which simultaneously collect during the same experiment three samples with fuel particles in the size ranges larger than 3 microns, larger than 6 microns and larger than 9 microns in geometric diameter. The radionuclide ratios, determined after gamma-spectrometry, were in good agreement with the theoretical calculations for the radionuclide-composition of the Chernobyl Nuclear Power Plant at the moment of the accident and the measured hot particles in soil in the early years after the accident. The number concentrations of airborne hot particles were derived from digital autoradiography. For wind resuspension, maximal concentrations of 2.6 coarse hot particles per 1000 m3 and during agricultural activities 36 coarse hot particles per 1000 m3 were measured. The geometric diameter of single hot particles was estimated to be between 6 and 12 microns.

  18. Coarse-graining two-dimensional turbulence via dynamical optimization

    NASA Astrophysics Data System (ADS)

    Turkington, Bruce; Chen, Qian-Yong; Thalabard, Simon

    2016-10-01

    A model reduction technique based on an optimization principle is employed to coarse-grain inviscid, incompressible fluid dynamics in two dimensions. In this reduction the spectrally-truncated vorticity equation defines the microdynamics, while the macroscopic state space consists of quasi-equilibrium trial probability densities on the microscopic phase space, which are parameterized by the means and variances of the low modes of the vorticity. A macroscopic path therefore represents a coarse-grained approximation to the evolution of a nonequilibrium ensemble of microscopic solutions. Closure in terms of the vector of resolved variables, namely, the means and variances of the low modes, is achieved by minimizing over all feasible paths the time integral of their mean-squared residual with respect to the Liouville equation. The equations governing the optimal path are deduced from Hamilton-Jacobi theory. The coarse-grained dynamics derived by this optimization technique contains a scale-dependent eddy viscosity, modified nonlinear interactions between the low mode means, and a nonlinear coupling between the mean and variance of each low mode. The predictive skill of this optimal closure is validated quantitatively by comparing it against direct numerical simulations. These tests show that good agreement is achieved without adjusting any closure parameters.

  19. High capacitance of coarse-grained carbide derived carbon electrodes

    SciTech Connect

    Dyatkin, Boris; Gogotsi, Oleksiy; Malinovskiy, Bohdan; Zozulya, Yuliya; Simon, Patrice; Gogotsi, Yury

    2016-01-01

    Here, we report exceptional electrochemical properties of supercapacitor electrodes composed of large, granular carbide-derived carbon (CDC) particles. We synthesized 70–250 μm sized particles with high surface area and a narrow pore size distribution, using a titanium carbide (TiC) precursor. Electrochemical cycling of these coarse-grained powders defied conventional wisdom that a small particle size is strictly required for supercapacitor electrodes and allowed high charge storage densities, rapid transport, and good rate handling ability. Moreover, the material showcased capacitance above 100 F g-1 at sweep rates as high as 250 mV s-1 in organic electrolyte. 250–1000 micron thick dense CDC films with up to 80 mg cm-2 loading showed superior areal capacitances. The material significantly outperformed its activated carbon counterpart in organic electrolytes and ionic liquids. Furthermore, large internal/external surface ratio of coarse-grained carbons allowed the resulting electrodes to maintain high electrochemical stability up to 3.1 V in ionic liquid electrolyte. In addition to presenting novel insights into the electrosorption process, these coarse-grained carbons offer a pathway to low-cost, high-performance implementation of supercapacitors in automotive and grid-storage applications.

  20. High capacitance of coarse-grained carbide derived carbon electrodes

    NASA Astrophysics Data System (ADS)

    Dyatkin, Boris; Gogotsi, Oleksiy; Malinovskiy, Bohdan; Zozulya, Yuliya; Simon, Patrice; Gogotsi, Yury

    2016-02-01

    We report exceptional electrochemical properties of supercapacitor electrodes composed of large, granular carbide-derived carbon (CDC) particles. Using a titanium carbide (TiC) precursor, we synthesized 70-250 μm sized particles with high surface area and a narrow pore size distribution. Electrochemical cycling of these coarse-grained powders defied conventional wisdom that a small particle size is strictly required for supercapacitor electrodes and allowed high charge storage densities, rapid transport, and good rate handling ability. The material showcased capacitance above 100 F g-1 at sweep rates as high as 250 mV s-1 in organic electrolyte. 250-1000 micron thick dense CDC films with up to 80 mg cm-2 loading showed superior areal capacitances. The material significantly outperformed its activated carbon counterpart in organic electrolytes and ionic liquids. Furthermore, large internal/external surface ratio of coarse-grained carbons allowed the resulting electrodes to maintain high electrochemical stability up to 3.1 V in ionic liquid electrolyte. In addition to presenting novel insights into the electrosorption process, these coarse-grained carbons offer a pathway to low-cost, high-performance implementation of supercapacitors in automotive and grid-storage applications.

  1. Insights on protein-DNA recognition by coarse grain modelling

    PubMed Central

    Poulain, Pierre; Saladin, Adrien; Hartmann, Brigitte; Prévost, Chantal

    2008-01-01

    Coarse grain modelling of macromolecules is a new approach potentially well adapted to answer numerous issues, ranging from physics to biology. We propose here an original DNA coarse grain model specifically dedicated to protein–DNA docking, a crucial, but still largely unresolved, question in molecular biology. Using a representative set of protein–DNA complexes, we first show that our model is able to predict the interaction surface between the macromolecular partners taken in their bound form. In a second part, the impact of the DNA sequence and electrostatics, together with the DNA and protein conformations on docking is investigated. Our results strongly suggest that the overall DNA structure mainly contributes in discriminating the interaction site on cognate proteins. Direct electrostatic interactions between phosphate groups and amino acids side chains strengthen the binding. Overall, this work demonstrates that coarse grain modelling can reveal itself a precious auxiliary for a general and complete description and understanding of protein–DNA association mechanisms. PMID:18478582

  2. Heterogeneity of coarse particles in an urban area.

    PubMed

    Lagudu, Uma Ramesh K; Raja, Suresh; Hopke, Philip K; Chalupa, David C; Utell, Mark J; Casuccio, Gary; Lersch, Traci L; West, Roger R

    2011-04-15

    The variation in composition and concentration of coarse particles in Rochester, a medium-sized city in western New York, was studied using UNC passive samplers and computer-controlled scanning electron microscopy (CCSEM). The samplers were deployed in a 5 × 5 grid (2 km × 2 km per grid cell) for 2-3 week periods in two seasons (September 2008 and May 2009) at 25 different sites across Rochester. CCSEM analysis yielded size and elemental composition for individual particles and analyzed more than 800 coarse particles per sample. Based on the composition as reflected in the fluoresced X-ray spectrum, the particles were grouped into classes with similar chemical compositions using an adaptive resonance theory (ART) network. The mass fractions of particles in the identified classes were then used to assess the homogeneity of composition and concentration across the measurement domain. These results illustrate how particle sampling using the UNC passive sampler coupled with CCSEM/ART can be used to determine the concentration and source of the coarse particulate matter at multiple sites. The particle compositions were dominated by elements suggesting that the major particle sources are road dust and biological particles. Considerable heterogeneity in both composition and concentration were observed between adjacent sites as indicated by cofficient of divergence analyses.

  3. Coarse-grained models for aqueous polyethylene glycol solutions.

    PubMed

    Choi, Eunsong; Mondal, Jagannath; Yethiraj, Arun

    2014-01-09

    A new coarse-grained force field is developed for polyethylene glycol (PEG) in water. The force field is based on the MARTINI model but with the big multipole water (BMW) model for the solvent. The polymer force field is reparameterized using the MARTINI protocol. The new force field removes the ring-like conformations seen in simulations of short chains with the MARTINI force field; these conformations are not observed in atomistic simulations. We also investigate the effect of using parameters for the end-group that are different from those for the repeat units, with the MARTINI and BMW/MARTINI models. We find that the new BMW/MARTINI force field removes the ring-like conformations seen in the MARTINI models and has more accurate predictions for the density of neat PEG. However, solvent-separated-pairs between chain ends and slow dynamics of the PEG reflect its own artifacts. We also carry out fine-grained simulations of PEG with bundled water clusters and show that the water bundling can lead to ring-like conformations of the polymer molecules. The simulations emphasize the pitfalls of coarse-graining several molecules into one site and suggest that polymer-solvent systems might be a stringent test for coarse-grained force fields.

  4. Coarse-Grained Model of SNARE-Mediated Docking

    PubMed Central

    Fortoul, Nicole; Singh, Pankaj; Hui, Chung-Yuen; Bykhovskaia, Maria; Jagota, Anand

    2015-01-01

    Synaptic transmission requires that vesicles filled with neurotransmitter molecules be docked to the plasma membrane by the SNARE protein complex. The SNARE complex applies attractive forces to overcome the long-range repulsion between the vesicle and membrane. To understand how the balance between the attractive and repulsive forces defines the equilibrium docked state we have developed a model that combines the mechanics of vesicle/membrane deformation with an apparently new coarse-grained model of the SNARE complex. The coarse-grained model of the SNARE complex is calibrated by comparison with all-atom molecular dynamics simulations as well as by force measurements in laser tweezer experiments. The model for vesicle/membrane interactions includes the forces produced by membrane deformation and hydration or electrostatic repulsion. Combining these two parts, the coarse-grained model of the SNARE complex with membrane mechanics, we study how the equilibrium docked state varies with the number of SNARE complexes. We find that a single SNARE complex is able to bring a typical synaptic vesicle to within a distance of ∼3 nm from the membrane. Further addition of SNARE complexes shortens this distance, but an overdocked state of >4–6 SNAREs actually increases the equilibrium distance. PMID:25954883

  5. Atomistic and Coarse-grained Simulations of Hexabenzocoronene Crystals

    NASA Astrophysics Data System (ADS)

    Ziogos, G.; Megariotis, G.; Theodorou, D. N.

    2016-08-01

    This study concerns atomistic and coarse-grained Molecular Dynamics simulations of pristine hexabenzocoronene (HBC) molecular crystals. HBC is a symmetric graphene flake of nanometric size that falls in the category of polyaromatic hydrocarbons, finding numerous applications in the field of organic electronics. The HBC molecule is simulated in its crystalline phase initially by means of an all-atom representation, where the molecules self- organize into well aligned molecular stacks, which in turn create a perfect monoclinic molecular crystal. The atomistic model reproduces fairly well the structural experimental properties and thus can be used as a reliable starting point for the development of a coarsegrained model following a bottom-up approach. The coarse-grained model is developed by applying Iterative Boltzmann Inversion, a systematic coarse-graining method which reproduces a set of target atomistic radial distribution functions and intramolecular distributions at the coarser level of description. This model allows the simulation of HBC crystals over longer time and length scales. The crystalline phase is analyzed in terms of the Saupe tensor and thermomechanical properties are probed at the atomistic level.

  6. Effects of Source-Apportioned Coarse Particulate Matter (PM) ...

    EPA Pesticide Factsheets

    The Cleveland Multiple Air Pollutant Study (CMAPS) is one of the first comprehensive studies conducted to evaluate particulate matter (PM) over local and regional scales. Cleveland and the nearby Ohio River Valley impart significant regional sources of air pollution including coal combustion and steel production. Size-fractionated PM (coarse, fine and ultrafine) were collected from an urban site (G.T. Craig (GTC)) and a rural site (Chippewa Lake monitor (CLM) located 53 km southwest of Cleveland) from July 2009 to June 2010. Following collection, resulting speciated PM data were apportioned to identify local industrial emission sources for each size fraction and location, indicating these samples were enriched with resident emission sources. This study was designed to determine whether exposure of the CMAPS coarse PM contributes to the exacerbation of allergic asthma. Non-sensitized and house dust mite (HDM)-sensitized female Balb/cJ mice (n= 8/group) were exposed via oropharyngeal (OP) aspiration to 100 g coarse fractions of one of five source apportioned groups representative of distinct time periods of 4-6 weeks (traffic, coal, steel 1, steel 2, or winter PM) and OP challenge with HDM conducted 2 hr following dosing with PM. Two days later, airway responsiveness to methacholine aerosol was assessed in anesthetized ventilated control and HDM mice. The HDM-allergic mice demonstrated increased airway reactivity in comparison to control mice. Bronchoalveolar l

  7. Optimization of Analytical Potentials for Coarse-Grained Biopolymer Models.

    PubMed

    Mereghetti, Paolo; Maccari, Giuseppe; Spampinato, Giulia Lia Beatrice; Tozzini, Valentina

    2016-08-25

    The increasing trend in the recent literature on coarse grained (CG) models testifies their impact in the study of complex systems. However, the CG model landscape is variegated: even considering a given resolution level, the force fields are very heterogeneous and optimized with very different parametrization procedures. Along the road for standardization of CG models for biopolymers, here we describe a strategy to aid building and optimization of statistics based analytical force fields and its implementation in the software package AsParaGS (Assisted Parameterization platform for coarse Grained modelS). Our method is based on the use and optimization of analytical potentials, optimized by targeting internal variables statistical distributions by means of the combination of different algorithms (i.e., relative entropy driven stochastic exploration of the parameter space and iterative Boltzmann inversion). This allows designing a custom model that endows the force field terms with a physically sound meaning. Furthermore, the level of transferability and accuracy can be tuned through the choice of statistical data set composition. The method-illustrated by means of applications to helical polypeptides-also involves the analysis of two and three variable distributions, and allows handling issues related to the FF term correlations. AsParaGS is interfaced with general-purpose molecular dynamics codes and currently implements the "minimalist" subclass of CG models (i.e., one bead per amino acid, Cα based). Extensions to nucleic acids and different levels of coarse graining are in the course.

  8. Parametrizing coarse grained models for molecular systems at equilibrium

    NASA Astrophysics Data System (ADS)

    Kalligiannaki, E.; Chazirakis, A.; Tsourtis, A.; Katsoulakis, M. A.; Plecháč, P.; Harmandaris, V.

    2016-10-01

    Hierarchical coarse graining of atomistic molecular systems at equilibrium has been an intensive research topic over the last few decades. In this work we (a) review theoretical and numerical aspects of different parametrization methods (structural-based, force matching and relative entropy) to derive the effective interaction potential between coarse-grained particles. All methods approximate the many body potential of mean force; resulting, however, in different optimization problems. (b) We also use a reformulation of the force matching method by introducing a generalized force matching condition for the local mean force in the sense that allows the approximation of the potential of mean force under both linear and non-linear coarse graining mappings (E. Kalligiannaki, et al., J. Chem. Phys. 2015). We apply and compare these methods to: (a) a benchmark system of two isolated methane molecules; (b) methane liquid; (c) water; and (d) an alkane fluid. Differences between the effective interactions, derived from the various methods, are found that depend on the actual system under study. The results further reveal the relation of the various methods and the sensitivities that may arise in the implementation of numerical methods used in each case.

  9. Detection of load application onto an optical fiber through changes in speckle patterns in an output light spot

    NASA Astrophysics Data System (ADS)

    Hasegawa, Makoto; Takeda, Ryo; Fujioka, Yuki

    2016-10-01

    For the purpose of investigating possibilities of utilizing, for sensing application, changes in speckle patterns to be observed in an output light spot from an optical fiber due to external disturbance, a certain level of load was applied onto an optical fiber through which laser beams emitted from a laser diode were propagating, and changes in the speckle patterns in the output light spot were investigated. In order to realize effective load application onto the optical fiber, a load application section was provided in which several ridges were intentionally provided onto opposite flat plates. A jacket-covered communication-grade multi-mode glass optical fiber was placed in the load application section so that corrugated bending of the fiber was intentionally induced via load application due to the ridges. A PV cell panel was irradiated with the output light spot from the optical fiber containing the speckle patterns therein. When weights were placed in the load application section, an output voltage from the PV cell panel was changed, indicating that the load application onto the optical fiber can be detected with this detection setup. Removal of the once-placed weights was also detected via changes in the PV cell panel output. Then, the load application onto the optical fiber and its removal was successfully detected via turn-on/off operations of an LED which was controlled in accordance with the changes in the output voltage level from the PV cell panel, in other words, through the changes in the speckle patterns.

  10. Numerical modeling of fiber specklegram sensors by using finite element method (FEM).

    PubMed

    Arístizabal, V H; Vélez, F J; Rueda, E; Gómez, N D; Gómez, J A

    2016-11-28

    Although experimental advances in the implementation and characterization of fiber speckle sensor have been reported, a suitable model to interpret the speckle-pattern variation under perturbation is desirable but very challenging to be developed due to the various factors influencing the speckle pattern. In this work, a new methodology based on the finite element method (FEM) for modeling and optimizing fiber specklegram sensors (FSSs) is proposed. The numerical method allows computational visualization and quantification, in near field, of changes of a step multi-mode fiber (SMMF) specklegram, due to the application of a uniformly distributed force line (UDFL). In turn, the local modifications of the fiber speckle produce changes in the optical power captured by a step single-mode fiber (SSMF) located just at the output end of the SMMF, causing a filtering effect that explains the operation of the FSSs. For each external force, the stress distribution and the propagations modes supported by the SMMF are calculated numerically by means of FEM. Then, those modes are vectorially superposed to reconstruct each perturbed fiber specklegram. Finally, the performance of the sensing mechanism is evaluated for different radius of the filtering SSMF and force-gauges, what evidences design criteria for these kinds of measuring systems. Results are in agreement with those theoretical and experimental ones previously reported.

  11. Online monitoring of gamma irradiated perfluorinated polymer optical fiber

    NASA Astrophysics Data System (ADS)

    Sporea, Dan; Mihai, Laura; Neguţ, Daniel; Stajanca, Pavol; Krebber, Katerina

    2016-04-01

    In this paper, we present the first results regarding the on-line monitoring of gamma-ray exposure effects on a commercial multi-mode perfluorinated polymer optical fiber (PF-POF), type GigaPOF-50SR from Chromis Fiberoptics. Our focus was to evaluate on-line the radiation induced attenuation (RIA) over a wide spectral range (320 nm - 1700 nm), in order to assess the fiber's radiation hardness and its possible use in radiation detection. An Ocean Optics QE65000 high sensitivity spectrometer and a StellarNet near-IR spectrometer were used to cover the spectral ranges 200 nm - 1μm and 900 nm - 1.6 μm, respectively. Electron paramagnetic resonance was used to monitor the recovery of the irradiation induced centers at room temperature. The study indicated that the optical fiber can be used as radiation monitor at low dose rates by measuring the attenuation in the UV, while higher dose rates irradiation can be observed by RIA monitoring at specific wavelengths in the visible spectral range.

  12. Coarse woody debris: Managing benefits and fire hazard in the recovering forest

    Treesearch

    James K. Brown; Elizabeth D. Reinhardt; Kylie A. Kramer

    2003-01-01

    Management of coarse woody debris following fire requires consideration of its positive and negative values. The ecological benefits of coarse woody debris and fire hazard considerations are summarized. This paper presents recommendations for desired ranges of coarse woody debris. Example simulations illustrate changes in debris over time and with varying management....

  13. Quantifying the coarse-root biomass of intensively managed loblolly pine plantations

    Treesearch

    Ashley T. Miller; H. Lee Allen; Chris A. Maier

    2006-01-01

    Most of the carbon accumulation during a forest rotation is in plant biomass and the forest floor. Most of the belowground biomass in older loblolly pine (Pinus taeda L.) forests is in coarse roots, and coarse roots ersist longer after harvest than aboveground biomass and fine oots. The main objective was to assess the carbon accumulation in coarse...

  14. Quantifying the coarse-root biomass of intensively managed loblolly pine plantations

    Treesearch

    Ashley T. Miller; H. Lee Allen; Chris A. Maier

    2006-01-01

    Most of the carbon accumulation during a forest rotation is in plant biomass and the forest floor. Most of the belowground biomass in older loblolly pine (Pinus taeda L.) forests is in coarse roots, and coarse roots persist longer after harvest than aboveground biomass and fine roots. The main objective was to assess the carbon accumulation in coarse...

  15. The multiscale coarse-graining method. XI. Accurate interactions based on the centers of charge of coarse-grained sites

    NASA Astrophysics Data System (ADS)

    Cao, Zhen; Voth, Gregory A.

    2015-12-01

    It is essential to be able to systematically construct coarse-grained (CG) models that can efficiently and accurately reproduce key properties of higher-resolution models such as all-atom. To fulfill this goal, a mapping operator is needed to transform the higher-resolution configuration to a CG configuration. Certain mapping operators, however, may lose information related to the underlying electrostatic properties. In this paper, a new mapping operator based on the centers of charge of CG sites is proposed to address this issue. Four example systems are chosen to demonstrate this concept. Within the multiscale coarse-graining framework, CG models that use this mapping operator are found to better reproduce the structural correlations of atomistic models. The present work also demonstrates the flexibility of the mapping operator and the robustness of the force matching method. For instance, important functional groups can be isolated and emphasized in the CG model.

  16. The multiscale coarse-graining method. XI. Accurate interactions based on the centers of charge of coarse-grained sites

    SciTech Connect

    Cao, Zhen; Voth, Gregory A.

    2015-12-28

    It is essential to be able to systematically construct coarse-grained (CG) models that can efficiently and accurately reproduce key properties of higher-resolution models such as all-atom. To fulfill this goal, a mapping operator is needed to transform the higher-resolution configuration to a CG configuration. Certain mapping operators, however, may lose information related to the underlying electrostatic properties. In this paper, a new mapping operator based on the centers of charge of CG sites is proposed to address this issue. Four example systems are chosen to demonstrate this concept. Within the multiscale coarse-graining framework, CG models that use this mapping operator are found to better reproduce the structural correlations of atomistic models. The present work also demonstrates the flexibility of the mapping operator and the robustness of the force matching method. For instance, important functional groups can be isolated and emphasized in the CG model.

  17. Photovoltaic fibers

    NASA Astrophysics Data System (ADS)

    Gaudiana, Russell; Eckert, Robert; Cardone, John; Ryan, James; Montello, Alan

    2006-08-01

    It was realized early in the history of Konarka that the ability to produce fibers that generate power from solar energy could be applied to a wide variety of applications where fabrics are utilized currently. These applications include personal items such as jackets, shirts and hats, to architectural uses such as awnings, tents, large covers for cars, trucks and even doomed stadiums, to indoor furnishings such as window blinds, shades and drapes. They may also be used as small fabric patches or fiber bundles for powering or recharging batteries in small sensors. Power generating fabrics for clothing is of particular interest to the military where they would be used in uniforms and body armor where portable power is vital to field operations. In strong sunlight these power generating fabrics could be used as a primary source of energy, or they can be used in either direct sunlight or low light conditions to recharge batteries. Early in 2002, Konarka performed a series of proof-of-concept experiments to demonstrate the feasibility of building a photovoltaic cell using dye-sensitized titania and electrolyte on a metal wire core. The approach taken was based on the sequential coating processes used in making fiber optics, namely, a fiber core, e.g., a metal wire serving as the primary electrode, is passed through a series of vertically aligned coating cups. Each of the cups contains a coating fluid that has a specific function in the photocell. A second wire, used as the counter electrode, is brought into the process prior to entering the final coating cup. The latter contains a photopolymerizable, transparent cladding which hardens when passed through a UV chamber. Upon exiting the UV chamber, the finished PV fiber is spooled. Two hundred of foot lengths of PV fiber have been made using this process. When the fiber is exposed to visible radiation, it generates electrical power. The best efficiency exhibited by these fibers is 6% with an average value in the 4

  18. Molecular Dynamics Trajectory Compression with a Coarse-Grained Model

    PubMed Central

    Cheng, Yi-Ming; Gopal, Srinivasa Murthy; Law, Sean M.; Feig, Michael

    2012-01-01

    Molecular dynamics trajectories are very data-intensive thereby limiting sharing and archival of such data. One possible solution is compression of trajectory data. Here, trajectory compression based on conversion to the coarse-grained model PRIMO is proposed. The compressed data is about one third of the original data and fast decompression is possible with an analytical reconstruction procedure from PRIMO to all-atom representations. This protocol largely preserves structural features and to a more limited extent also energetic features of the original trajectory. PMID:22025759

  19. Coarse-Grained Models for Protein-Cell Membrane Interactions

    PubMed Central

    Bradley, Ryan; Radhakrishnan, Ravi

    2015-01-01

    The physiological properties of biological soft matter are the product of collective interactions, which span many time and length scales. Recent computational modeling efforts have helped illuminate experiments that characterize the ways in which proteins modulate membrane physics. Linking these models across time and length scales in a multiscale model explains how atomistic information propagates to larger scales. This paper reviews continuum modeling and coarse-grained molecular dynamics methods, which connect atomistic simulations and single-molecule experiments with the observed microscopic or mesoscale properties of soft-matter systems essential to our understanding of cells, particularly those involved in sculpting and remodeling cell membranes. PMID:26613047

  20. Statistical coarse-graining of molecular dynamics into peridynamics.

    SciTech Connect

    Silling, Stewart Andrew; Lehoucq, Richard B.

    2007-10-01

    This paper describes an elegant statistical coarse-graining of molecular dynamics at finite temperature into peridynamics, a continuum theory. Peridynamics is an efficient alternative to molecular dynamics enabling dynamics at larger length and time scales. In direct analogy with molecular dynamics, peridynamics uses a nonlocal model of force and does not employ stress/strain relationships germane to classical continuum mechanics. In contrast with classical continuum mechanics, the peridynamic representation of a system of linear springs and masses is shown to have the same dispersion relation as the original spring-mass system.

  1. A fusion approach for coarse-to-fine target recognition

    NASA Astrophysics Data System (ADS)

    Folkesson, Martin; Grönwall, Christina; Jungert, Erland

    2006-04-01

    A fusion approach in a query based information system is presented. The system is designed for querying multimedia data bases, and here applied to target recognition using heterogeneous data sources. The recognition process is coarse-to-fine, with an initial attribute estimation step and a following matching step. Several sensor types and algorithms are involved in each of these two steps. An independence of the matching results, on the origin of the estimation results, is observed. It allows for distribution of data between algorithms in an intermediate fusion step, without risk of data incest. This increases the overall chance of recognising the target. An implementation of the system is described.

  2. Transferability of coarse-grained force fields: The polymer case

    NASA Astrophysics Data System (ADS)

    Carbone, Paola; Varzaneh, Hossein Ali Karimi; Chen, Xiaoyu; Müller-Plathe, Florian

    2008-02-01

    A key question for all coarse-graining methodologies is the degree of transferability of the resulting force field between various systems and thermodynamic conditions. Here we present a detailed study of the transferability over different thermodynamic states of a coarse-grained (CG) force field developed using the iterative Boltzmann inversion method. The force field is optimized against distribution functions obtained from atomistic simulations. We analyze the polymer case by investigating the bulk of polystyrene and polyamide-6,6 whose coarse-grained models differ in the chain length and in the number of atoms lumped in one bead. The effect of temperature and pressure on static, dynamic, and thermodynamic properties is tested by comparing systematically the coarse-grain results with the atomistic ones. We find that the CG model describing the polystyrene is transferable only in a narrow range of temperature and it fails in describing the change of the bulk density when temperature is 80K lower than the optimization one. Moreover the calculation of the self-diffusion coefficient shows that the CG model is characterized by a faster dynamics than the atomistic one and that it overestimates the isothermal compressibility. On the contrary, the polyamide-6,6 CG model turns out to be fully transferable between different thermodynamic conditions. The transferability is checked by changing either the temperature or the pressure of the simulation. We find that, in this case, the CG model is able to follow all the intra- and interstructural rearrangements caused by the temperature changes. In addition, while at low temperature the difference between the CG and atomistic dynamics is remarkable due to the presence of hydrogen bonds in the atomistic systems, for high temperatures, the speedup of the CG dynamics is strongly reduced, leading to a CG diffusion coefficient only six times bigger than the atomistic one. Moreover, the isothermal compressibility calculated at

  3. Dynamical coarse grained models with realistic time dependence

    NASA Astrophysics Data System (ADS)

    Andersen, Hans

    2015-03-01

    Coarse grained (CG) models of molecular systems, with fewer mechanical degrees of freedom than an all-atom model, are used extensively in chemical physics. It is generally accepted that a coarse grained model that accurately describes equilibrium structural properties (as a result of having a well constructed CG potential energy function) does not necessarily exhibit appropriate dynamical behavior when simulated using conservative Hamiltonian dynamics for the CG degrees of freedom on the CG potential energy surface. Attempts to develop accurate CG dynamic models usually focus on replacing Hamiltonian motion by stochastic but Markovian dynamics on that surface, such as Langevin or Brownian dynamics. However, depending on the nature of the system and the extent of the coarse graining, a Markovian dynamics for the CG degrees of freedom may not be appropriate. We consider the problem of constructing dynamic CG models within the context of the Multi-Scale Coarse Graining (MS-CG) method of Voth and coworkers. We propose a method of converting an MS-CG model into a dynamic CG model by adding degrees of freedom to it in the form of a small number of fictitious particles that interact with the CG degrees of freedom in simple ways and that are subject to Langevin forces. The dynamic models are members of a class of nonlinear systems interacting with special heat baths that was studied by Zwanzig [R. Zwanzig, J. Stat. Phys. 9, 215 (1973)]. The dynamic models generate a non-Markovian dynamics for the CG degrees of freedom, but they can be easily simulated using standard molecular dynamics simulation programs. We present tests of this method on a series of simple examples that demonstrate that the method provides realistic dynamical CG models that have non-Markovian or close to Markovian behavior that is consistent with the actual dynamical behavior of the all-atom system used to construct the CG model. The dynamic CG models have computational requirements that are similar to

  4. Residual gas saturation effects on hydraulic conductivity of coarse sand

    NASA Astrophysics Data System (ADS)

    Princ, Tomas; Reis Fideles, Helena Maria; Snehota, Michal; Sacha, Jan; Cislerova, Milena

    2017-04-01

    The aim of the first part of this study was to experimentally determine the relationship between gas residual saturation (Sgr) and actual hydraulic conductivity (K) of coarse sand. Sgr indicates the ratio of entrapped air volume to pore volume of the sample. The value of residual gas saturation value determined in experiments exhibits temporal variability (due to history of wetting and drying, due to redistribution, air dissolution etc.), but many two-phase models assume value of Sgr to be constant. The K(Sgr) relationship was determined in series of constant head infiltration-outflow experiments. The first runs was performed on fully saturated sample. After the first infiltration run and then after each subsequent infiltration run, sample was drained under tension on a sand tank. Sgr was determined gravimetrically before each infiltration run. The value of K was determined using a Darcy's law from measured steady state flux and each measurement then provided one value of K(Sgr). Several relative hydraulic conductivity models were tested to fit the measured points. In the second part of this study the aim was to compare hydraulic conductivities predicted from the retention curves by Mualem - van Genuchten model and measured K(Sgr). The performance of both concepts was tested in numerical simulation of the complex infiltration-outflow experiment using TOUGH2 multiphase model (Pruess et al., 2012). TOUGH2 model considers Sgr as a point, below which gas phase becomes immobile, but its content still can be reduced by dissolution into water. The simulated infiltration-outflow experiment was previously conducted on a compacted sample composed of fine, medium coarse and coarse sand (Sněhota et al., 2015). The data of water content distribution during various stages of the experiment were determined by means of neutron tomography. The Levenberg-Marquardt algorithm was used for parameter optimization. Four parameters (permeability and residual gas saturation of fine and

  5. Physical property data on coarse anthracite waste. Report of investigations

    SciTech Connect

    Stewart, B.M.; Atkins, L.A.

    1983-07-01

    Since 1974, a large amount of data has been developed concerning the physical properties and stability characteristics of waste generated by the mining and preparation of bituminous coal. However, very little information has been developed on the properties and characteristics of anthracite waste. During this Bureau of Mines research project, coarse anthracite breaker refuse from five sites in eastern Pennsylvania was sampled and the physical properties, which indicate stability characteristics, were determined in the laboratory. Stability analyses were conducted on six theoretical anthracite waste embankments. These analyses show the effects on minimum safety factors of geometry, phreatic surface level, and physical properties.

  6. Coarse fraction of soils from building rubble (WWII)

    NASA Astrophysics Data System (ADS)

    Mekiffer, Beate; Wessolek, Gerd; Scheytt, Traugott; Bussert, Robert; Nehls, Thomas

    2010-05-01

    Soils, resulting from building rubble of WWII are wide spread in whole Europe. The parent material for pedogenesis originates from different kinds of buildings, which where destroyed of different ways. Also the kind of sorting and disposing was varying for this material. So the most important feature of soils, resulting from building rubble of WWII, is their heterogeneity. We investigated samples of soils developed from building rubble to answer the following questions: ­ What are the amounts of coarse fraction and what are their main components? ­ What are the chemical properties and what is the crystalline mineral composition of technogenic components? ­ What is the release of ions from coarse technogenic components? We sieved and hand sorted the materials, used the X-ray diffractometry and X-ray fluorescence spectroscopy and measured the ions released in 1:2-extract. In most cases, the soils have a high amount of coarse fraction (> 2mm) (median 25% w/w, N=52). Dominating components in the coarse fraction are in the order of decreasing abundance: bricks, mortar (incl. plaster and stucco), slag, ashes and unburned coals. The analyzed components show alkalescent to alkaline pH-values. 75% of the samples show low electrical conductivities of up to 141 µS/cm. Bricks mainly consist of Si oxides, followed by oxides of Al, Ca, Fe, Mg and K. X-Ray-diffractometry of bricks showed, that most common minerals are clay minerals (Kaolinit, Illit, Montmorillonit and Chlorit), Quarz, and Carbonates (Calcite and Dolomite, Siderite). Bricks contain Fe-Oxides (Hematite, Goethite), Sulphates and Sulfides (Gypsum, Pyrite, Markasite) in lower amounts. 5-20 % of the minerals are x-ray-amorphous. Mortar is characterized by a high amount of silicates (nearby 80%). The samples showed a lower percentage of Al- and Ca-compounds than bricks. Chemical composition of ashes and slag varies in wide ranges, depending on their genesis. We found mainly ashes from stove heating. They contained

  7. Coarse-grained incompressible magnetohydrodynamics: analyzing the turbulent cascades

    NASA Astrophysics Data System (ADS)

    Aluie, Hussein

    2017-02-01

    We formulate a coarse-graining approach to the dynamics of magnetohydrodynamic (MHD) fluids at a continuum of length-scales ℓ. In this methodology, effective equations are derived for the observable velocity and magnetic fields spatially-averaged at an arbitrary scale of resolution. The microscopic equations for the ‘bare’ velocity and magnetic fields are ‘renormalized’ by coarse-graining to yield macroscopic effective equations that contain both a subscale stress and a subscale electromotive force (EMF) generated by nonlinear interaction of eliminated fields and plasma motions. Particular attention is given to the effects of these subscale terms on the balances of the quadratic invariants of ideal incompressible MHD—energy, cross-helicity and magnetic helicity. At large coarse-graining length-scales, the direct dissipation of the invariants by microscopic mechanisms (such as molecular viscosity and Spitzer resistivity) is shown to be negligible. The balance at large scales is dominated instead by the subscale nonlinear terms, which can transfer invariants across scales, and are interpreted in terms of work concepts for energy and in terms of topological flux-linkage for the two helicities. An important application of this approach is to MHD turbulence, where the coarse-graining length ℓ lies in the inertial cascade range. We show that in the case of sufficiently rough velocity and/or magnetic fields, the nonlinear inter-scale transfer need not vanish and can persist to arbitrarily small scales. Although closed expressions are not available for subscale stress and subscale EMF, we derive rigorous upper bounds on the effective dissipation they produce in terms of scaling exponents of the velocity and magnetic fields. These bounds provide exact constraints on phenomenological theories of MHD turbulence in order to allow the nonlinear cascade of energy and cross-helicity. On the other hand, we prove a very strong version of the Woltjer-Taylor conjecture

  8. A Variation Code Accounts for the Perceived Roughness of Coarsely Textured Surfaces

    PubMed Central

    Goodman, James M.; Bensmaia, Sliman J.

    2017-01-01

    For decades, the dominant theory of roughness coding in the somatosensory nerves posited that perceived roughness was determined by the spatial pattern of activation in one population of tactile nerve fibers, namely slowly adapting type 1 (SA1) afferents. Indeed, the perceived roughness of coarsely textured surfaces tracks the spatial variation in SA1 responses – the degree to which response strength varies across SA1 afferents. However, in a later study, the roughness of a different set of dot patterns was found to be a monotonic function of dot spacing, a result interpreted as evidence that roughness was determined by the strength of SA1 responses – the population firing rate – rather than their spatial layout. Then again, the spatial variation hypothesis was not tested directly as afferent responses to the conflicting patterns were not measured. To fill this gap, we simulated afferent responses to the dot patterns used in these roughness coding experiments using a model of skin mechanics. We then implemented the spatial variation and firing rate models of roughness based on these simulated responses to generate predictions of perceived roughness. We found that the spatial variation model accounts for perceived roughness under all tested conditions whereas the firing rate model does not. PMID:28440308

  9. A Variation Code Accounts for the Perceived Roughness of Coarsely Textured Surfaces.

    PubMed

    Goodman, James M; Bensmaia, Sliman J

    2017-04-25

    For decades, the dominant theory of roughness coding in the somatosensory nerves posited that perceived roughness was determined by the spatial pattern of activation in one population of tactile nerve fibers, namely slowly adapting type 1 (SA1) afferents. Indeed, the perceived roughness of coarsely textured surfaces tracks the spatial variation in SA1 responses - the degree to which response strength varies across SA1 afferents. However, in a later study, the roughness of a different set of dot patterns was found to be a monotonic function of dot spacing, a result interpreted as evidence that roughness was determined by the strength of SA1 responses - the population firing rate - rather than their spatial layout. Then again, the spatial variation hypothesis was not tested directly as afferent responses to the conflicting patterns were not measured. To fill this gap, we simulated afferent responses to the dot patterns used in these roughness coding experiments using a model of skin mechanics. We then implemented the spatial variation and firing rate models of roughness based on these simulated responses to generate predictions of perceived roughness. We found that the spatial variation model accounts for perceived roughness under all tested conditions whereas the firing rate model does not.

  10. Fiber Length Measurement In Pulp And Paper Industry

    NASA Astrophysics Data System (ADS)

    Piirainen, Raili A.

    1986-10-01

    For the pulp and paper maker, product quality and production costs are the major factors that determine profitability. Quality has to be high enough to satisfy the customer and costs low enough to maintain competitiveness. Accurate and readily available fiber length information is fast becoming one of the most important control factors to achieve these targets. Measurement of fiber length has been difficult and time consuming in the past --- appli-cation to production almost impossible due to the historical nature of the data. The Kajaani fiber length analyzer has revolutionized fiber length analysis. Even more accurate than the microscopic method and infinitely faster than mechanical classifiers, such as Bauer McNett or Clark classifiers, the Kajaani analyzer opens new horizons for the paper maker. The Kajaani method is an optical method and is based on the ability of fibers to change the direction of light polarization. With no critical sample preparation, the results are ready in a few minutes. During this time, the analyzer counts and measures over 3000 individual fibers. Results are printed out either in graphic or numerical form. Some of the typical applications of the Kajaani fiber length analyzer are to determine hardwood/softwood ratios in pulp and paper mills both in brownstock and stock preparation areas, to predict strength properties of mechanical pulp based on the fiber length information, to measure the coarseness of the fibers, to evaluate screening and refining processes and to check the quality of purchased pulp.

  11. Milk production and nutrient digestibility by dairy cows when fed exogenous amylase with coarsely ground dry corn.

    PubMed

    Weiss, W P; Steinberg, W; Engstrom, M A

    2011-05-01

    The digestibility of starch provided by coarsely ground corn is often low, which reduces the digestible energy (DE) concentration of the diet. We hypothesized that adding exogenous amylase to diets based on coarsely ground dent corn would increase dietary DE resulting in greater milk production. Total-tract nutrient digestibility was measured in a partially replicated Latin square experiment (6 cows and 4 periods) with a 2 × 2 factorial arrangement of treatments. Diets had 26 or 31% starch with or without exogenous amylase (amylase was added to the concentrate mixes at the feed mill). In the low and high starch diets, coarsely ground dry corn (mean particle size=1.42 mm) provided 43 and 62% of total dietary starch (corn silage provided most of the remaining starch). No treatment interactions were observed. High starch diets had greater dry matter (DM), organic matter, and energy digestibility than low starch diets, and diets with amylase had greater neutral detergent fiber digestibility than diets without amylase. Digestibility of starch averaged 88% and was not affected by treatment. A long-term (98-d) lactation study with 48 Holstein cows (74 d in milk) was conducted using 3 of the diets (low starch diets with and without amylase and the high starch diet without amylase). Addition of amylase to a diet with 26% starch did not affect intake, milk yield, milk composition, body weight, or body condition. Cows fed the diet with 31% starch had greater DM and DE intakes; yields of milk, fat, and protein; and feed efficiency than those fed diets with 26% starch. Milk composition was not affected by starch concentration. Adding exogenous amylase to a lower starch diet did not make the diet nutritionally equivalent to a higher starch diet. Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  12. Fiber resources

    Treesearch

    P. J. Ince

    2004-01-01

    In economics, primary inputs or factors of production define the term ‘resources.’ Resources include land resources (plants, animals, and minerals), labor, capital, and entrepreneurship. Almost all pulp and paper fiber resources are plant materials obtained from trees or agricultural crops. These resources encompass plant materials harvested directly from the land (...

  13. Fiber crops

    USDA-ARS?s Scientific Manuscript database

    Much research continues to develop renewable, recyclable, sustainable, and bio-based products from agricultural feed stocks such as cotton and flax fiber. Primary requirements are sustainable production, low cost, and consistent and known quality. To better understand these products, research contin...

  14. Suppression of fiber modal noise induced radial velocity errors for bright emission-line calibration sources

    SciTech Connect

    Mahadevan, Suvrath; Halverson, Samuel; Ramsey, Lawrence; Venditti, Nick

    2014-05-01

    Modal noise in optical fibers imposes limits on the signal-to-noise ratio (S/N) and velocity precision achievable with the next generation of astronomical spectrographs. This is an increasingly pressing problem for precision radial velocity spectrographs in the near-infrared (NIR) and optical that require both high stability of the observed line profiles and high S/N. Many of these spectrographs plan to use highly coherent emission-line calibration sources like laser frequency combs and Fabry-Perot etalons to achieve precision sufficient to detect terrestrial-mass planets. These high-precision calibration sources often use single-mode fibers or highly coherent sources. Coupling light from single-mode fibers to multi-mode fibers leads to only a very low number of modes being excited, thereby exacerbating the modal noise measured by the spectrograph. We present a commercial off-the-shelf solution that significantly mitigates modal noise at all optical and NIR wavelengths, and which can be applied to spectrograph calibration systems. Our solution uses an integrating sphere in conjunction with a diffuser that is moved rapidly using electrostrictive polymers, and is generally superior to most tested forms of mechanical fiber agitation. We demonstrate a high level of modal noise reduction with a narrow bandwidth 1550 nm laser. Our relatively inexpensive solution immediately enables spectrographs to take advantage of the innate precision of bright state-of-the art calibration sources by removing a major source of systematic noise.

  15. The multiscale coarse-graining method. X. Improved algorithms for constructing coarse-grained potentials for molecular systems.

    PubMed

    Das, Avisek; Lu, Lanyuan; Andersen, Hans C; Voth, Gregory A

    2012-05-21

    The multiscale coarse-graining (MS-CG) method uses simulation data for an atomistic model of a system to construct a coarse-grained (CG) potential for a coarse-grained model of the system. The CG potential is a variational approximation for the true potential of mean force of the degrees of freedom retained in the CG model. The variational calculation uses information about the atomistic positions and forces in the simulation data. In principle, the resulting MS-CG potential will be an accurate representation of the true CG potential if the basis set for the variational calculation is complete enough and the canonical distribution of atomistic states is well sampled by the data set. In practice, atomistic configurations that have very high potential energy are not sampled. As a result there usually is a region of CG configuration space that is not sampled and about which the data set contains no information regarding the gradient of the true potential. The MS-CG potential obtained from a variational calculation will not necessarily be accurate in this unsampled region. A priori considerations make it clear that the true CG potential of mean force must be very large and positive in that region. To obtain an MS-CG potential whose behavior in the sampled region is determined by the atomistic data set, and whose behavior in the unsampled region is large and positive, it is necessary to intervene in the variational calculation in some way. In this paper, we discuss and compare two such methods of intervention, which have been used in previous MS-CG calculations for dealing with nonbonded interactions. For the test systems studied, the two methods give similar results and yield MS-CG potentials that are limited in accuracy only by the incompleteness of the basis set and the statistical error of associated with the set of atomistic configurations used. The use of such methods is important for obtaining accurate CG potentials.

  16. Effects of Elevated Temperature on Concrete with Recycled Coarse Aggregates

    NASA Astrophysics Data System (ADS)

    Salau, M. A.; Oseafiana, O. J.; Oyegoke, T. O.

    2015-11-01

    This paper discusses the effects of heating temperatures of 200°C, 400°C and 600°C each for 2 hours at a heating rate of 2.5°C/min on concrete with the content of Natural Coarse Aggregates (NCA) partially replaced with Recycled Coarse Aggregates (RCA), obtained from demolished building in the ratio of 0%, 15% and 30%.There was an initial drop in strength from 100°C to 200°C which is suspected to be due to the relatively weak interfacial bond between the RCA and the hardened paste within the concrete matrix;a gradual increase in strength continued from 200°C to 450°C and steady drop occurred again as it approached 600°C.With replacement proportion of 0%, 15% and 30% of NCA and exposure to peak temperature of 600°C, a relative concrete strength of 23.6MPa, 25.3MPa and 22.2MPa respectively can be achieved for 28 days curing age. Furthermore, RAC with 15% NCA replacement when exposed to optimum temperature of 450°C yielded high compressive strength comparable to that of control specimen (normal concrete). In addition, for all concrete samples only slight surface hairline cracks were noticed as the temperature approached 400°C. Thus, the RAC demonstrated behavior just like normal concrete and may be considered fit for structural use.

  17. Effective surface coverage of coarse-grained soft matter.

    PubMed

    Craven, Galen T; Popov, Alexander V; Hernandez, Rigoberto

    2014-12-11

    The surface coverage of coarse-grained macromolecules bound to a solid substrate is not simply proportional to the two-dimensional number density because macromolecules can overlap. As a function of the overlap probability δ, we have developed analytical formulas and computational models capable of characterizing this nonlinear relationship. For simplicity, we ignore site-site interactions that would be induced by length-scale mismatches between binding sites and the radius of gyration of the incident coarse-grained macromolecular species. The interactions between macromolecules are modeled with a finite bounded potential that allows multiple macromolecules to occupy the same binding site. The softness of the bounded potential is thereby reduced to the single parameter δ. Through variation of this parameter, completely hard (δ = 0) and completely soft (δ = 1) behavior can be bridged. For soft macromolecular interactions (δ > 0), multiple occupancy reduces the fraction of sites ϕ occupied on the substrate. We derive the exact transition probability between sequential configurations and use this probability to predict ϕ and the distribution of occupied sites. Due to the complexity of the exact ϕ expressions and their analytical intractability at the thermodynamic limit, we apply a simplified mean-field (MF) expression for ϕ. The MF model is found to be in excellent agreement with the exact result. Both the exact and MF models are applied to an example dynamical system with multibody interactions governed by a stochastic bounded potential. Both models show agreement with results measured from simulation.

  18. A coarse grain model for protein-surface interactions.

    PubMed

    Wei, Shuai; Knotts, Thomas A

    2013-09-07

    The interaction of proteins with surfaces is important in numerous applications in many fields-such as biotechnology, proteomics, sensors, and medicine--but fundamental understanding of how protein stability and structure are affected by surfaces remains incomplete. Over the last several years, molecular simulation using coarse grain models has yielded significant insights, but the formalisms used to represent the surface interactions have been rudimentary. We present a new model for protein surface interactions that incorporates the chemical specificity of both the surface and the residues comprising the protein in the context of a one-bead-per-residue, coarse grain approach that maintains computational efficiency. The model is parameterized against experimental adsorption energies for multiple model peptides on different types of surfaces. The validity of the model is established by its ability to quantitatively and qualitatively predict the free energy of adsorption and structural changes for multiple biologically-relevant proteins on different surfaces. The validation, done with proteins not used in parameterization, shows that the model produces remarkable agreement between simulation and experiment.

  19. Simulating the Entropic Collapse of Coarse-Grained Chromosomes

    PubMed Central

    Shendruk, Tyler N.; Bertrand, Martin; de Haan, Hendrick W.; Harden, James L.; Slater, Gary W.

    2015-01-01

    Depletion forces play a role in the compaction and decompaction of chromosomal material in simple cells, but it has remained debatable whether they are sufficient to account for chromosomal collapse. We present coarse-grained molecular dynamics simulations, which reveal that depletion-induced attraction is sufficient to cause the collapse of a flexible chain of large structural monomers immersed in a bath of smaller depletants. These simulations use an explicit coarse-grained computational model that treats both the supercoiled DNA structural monomers and the smaller protein crowding agents as combinatorial, truncated Lennard-Jones spheres. By presenting a simple theoretical model, we quantitatively cast the action of depletants on supercoiled bacterial DNA as an effective solvent quality. The rapid collapse of the simulated flexible chromosome at the predicted volume fraction of depletants is a continuous phase transition. Additional physical effects to such simple chromosome models, such as enthalpic interactions between structural monomers or chain rigidity, are required if the collapse is to be a first-order phase transition. PMID:25692586

  20. Transport of fine sediment over a coarse, immobile riverbed

    USGS Publications Warehouse

    Grams, Paul E.; Wilcock, Peter R.

    2014-01-01

    Sediment transport in cobble-boulder rivers consists mostly of fine sediment moving over a coarse, immobile bed. Transport rate depends on several interrelated factors: boundary shear stress, the grain size and volume of fine sediment, and the configuration of fine sediment into interstitial deposits and bed forms. Existing models do not incorporate all of these factors. Approaches that partition stress face a daunting challenge because most of the boundary shear is exerted on immobile grains. We present an alternative approach that divides the bed into sand patches and interstitial deposits and is well constrained by two clear end-member cases: full sand cover and absence of sand. Entrainment from sand patches is a function of their aerial coverage. Entrainment from interstices among immobile grains is a function of sand elevation relative to the size of the immobile grains. The bed-sand coverage function is used to predict the ratio of the rate of entrainment from a partially covered bed to the rate of entrainment from a completely sand-covered bed, which is determined using a standard sand transport model. We implement the bed-sand coverage function in a morphodynamic routing model and test it against observations of sand bed elevation and suspended sand concentration for conditions of nonuniform fine sediment transport in a large flume with steady uniform flow over immobile hemispheres. The results suggest that this approach may provide a simple and robust method for predicting the transport and migration of fine sediment through rivers with coarse, immobile beds.

  1. Interrogating Nucleosome Positioning Through Coarse-Grain Molecular Simulation

    NASA Astrophysics Data System (ADS)

    Freeman, Gordon S.; Hinckley, Daniel M.; Ortiz, Vanessa; de Pablo, Juan J.

    2012-02-01

    Nucleosome positioning plays a crucial role in biology. As the fundamental unit in chromosome structure, the nucleosome core particle (NCP) binds to approximately 147 DNA base pairs. The location of bound NCPs in the genome, therefore, affects gene expression. The specific positioning of NCPs has been experimentally probed and competing viewpoints have been presented in the literature. Models for nucleosome positioning based on sequence-dependent flexibility (a genomic ``code" for nucleosome positioning) have been demonstrated to explain available experimental data. However, so do statistical models with no built-in sequence preference; the driving force for NCP positioning therefore remains an open question. We use a coarse-grain model for the NCP in combination with advanced sampling techniques to probe the sequence preference of NCPs. We present a method for determining the relative affinity of two DNA sequences for the NCP and use this method to compare high- and low-affinity sequences. We discuss several coarse-grain protein models with varying level of detail to examine the impact of model resolution on the agreement of our results with experimental evidence. We also investigate the dynamics of the NCP-DNA complex and their dependence on system characteristics.

  2. Deformation Behaviour of Coarse Grain Alumina under Shock Loading

    NASA Astrophysics Data System (ADS)

    Gupta, Satish

    2013-06-01

    To develop better understanding of the shock wave induced deformation behavior of coarse grain alumina ceramics, and for measurement of its Hugoniot Elastic Limit (HEL), in-situ and recovery gas gun experiments have been carried out on coarse grain alumina (grain size ~ 10 μm), prepared in the form of discs (>99.9% TMD) by pressure-less sintering of alpha alumina powder at 1583 K. The HEL value of 1.9 GPa has been determined from the kink in the pressure history recorded using piezoresistance gauge and also from the free surface velocity history of the sample shocked to 9 GPa. The nano-indentation measurements on the alumina samples shocked to 6.5 GPa showed hardness value 15% lower than 21.3 GPa for unshocked alumina, and strong Indentation Size Effect (ISE); the hardness value was still lower and the ISE was stronger for the sample shocked to 12 GPa. The XRD measurements showed reduced particle size and increased microstrains in the shocked alumina fragments. SEM, FESEM and TEM measurements on shock treated samples showed presence of grain localized micro- and nano-scale deformations, micro-cleavages, grain-boundary microcracks, extensive shear induced deformations, and localized micro-fractures, etc. These observations led to the development of a qualitative model for the damage initiation and its subsequent growth mechanisms in shocked alumina. The work performed in collaboration with K.D. Joshi of BARC and A.K. Mukhopadhyay of CGCRI.

  3. Measurement of coarse aerosols in workplaces. A review.

    PubMed

    Vincent, J H

    1994-01-01

    Coarse aerosol fractions in workplaces are sampled if it is felt that particles of all sizes may pose a risk to health. Although the so-called 'total' aerosol has been widely used to refer to the relevant coarse fraction, practical measurement has been very dependent on the actual sampling instrument used. This in turn has led to great uncertainty about what was being measured. In the 1980s, the concept of inhalability was proposed, based on the aerosol particle size fraction that enters the human head through the nose and/or mouth during breathing. Now there is substantial agreement by most of the world's major criteria-setting bodies on a quantitative definition taking the form of a single curve describing the probability of inhalation as a function of particle aerodynamic diameter. This definition now forms a truly health-related 'yardstick' against which to assess the performances of practical sampling devices. In turn, more and more countries are beginning to adopt the new criterion for health-related aerosol measurement in their standards, replacing the old 'total' aerosol concept. Experiments in wind tunnels to investigate the performances of previous samplers for 'total' aerosol show that most of them do not satisfactorily match the new inhalability criterion. A small number of samplers designed specifically for the inhalable fraction have been proposed and are available commercially. They include samplers for both static (or area) and personal sampling.

  4. A coarse-grained model of microtubule self-assembly

    NASA Astrophysics Data System (ADS)

    Regmi, Chola; Cheng, Shengfeng

    Microtubules play critical roles in cell structures and functions. They also serve as a model system to stimulate the next-generation smart, dynamic materials. A deep understanding of their self-assembly process and biomechanical properties will not only help elucidate how microtubules perform biological functions, but also lead to exciting insight on how microtubule dynamics can be altered or even controlled for specific purposes such as suppressing the division of cancer cells. Combining all-atom molecular dynamics (MD) simulations and the essential dynamics coarse-graining method, we construct a coarse-grained (CG) model of the tubulin protein, which is the building block of microtubules. In the CG model a tubulin dimer is represented as an elastic network of CG sites, the locations of which are determined by examining the protein dynamics of the tubulin and identifying the essential dynamic domains. Atomistic MD modeling is employed to directly compute the tubulin bond energies in the surface lattice of a microtubule, which are used to parameterize the interactions between CG building blocks. The CG model is then used to study the self-assembly pathways, kinetics, dynamics, and nanomechanics of microtubules.

  5. Electronically coarse-grained molecular dynamics using quantum Drude oscillators

    NASA Astrophysics Data System (ADS)

    Jones, A. P.; Crain, J.; Cipcigan, F. S.; Sokhan, V. P.; Modani, M.; Martyna, G. J.

    2013-12-01

    Standard molecular dynamics (MD) simulations generally make use of a basic description of intermolecular forces which consists of fixed, pairwise, atom-centred Coulomb, van der Waals and short-range repulsive terms. Important interactions such as many-body polarisation and many-body dispersion which are sensitive to changes in the environment are usually neglected, and their effects treated effectively within mean-field approximations to reproduce a single thermodynamic state point or physical environment. This leads to difficulties in modelling the complex interfaces of interest today where the behaviour may be quite different from the regime of parameterisation. Here, we describe the construction and properties of a Gaussian coarse-grained electronic structure, which naturally generates many-body polarisation and dispersion interactions. The electronic structure arises from a fully quantum mechanical treatment of a set of distributed quantum Drude oscillators (QDOs), harmonic atoms which interact with each other and other moieties via electrostatic (Coulomb) interactions; this coarse-grained approach is capable of describing many-body polarisation and dispersion but not short-range interactions which must be parametrised. We describe how on-the-fly forces due to this exchange-free Gaussian model may be generated with linear scale in the number of atoms in the system using an adiabatic path integral molecular dynamics for quantum Drude oscillators technique (APIMD-QDO). We demonstrate the applicability of the QDO approach to realistic systems via a study of the liquid-vapour interface of water.

  6. Effective mobility of dislocations from systematic coarse-graining

    NASA Astrophysics Data System (ADS)

    Kooiman, M.; Hütter, M.; Geers, MGD

    2015-06-01

    The dynamics of large amounts of dislocations governs the plastic response of crystalline materials. In this contribution we discuss the relation between the mobility of discrete dislocations and the resulting flow rule for coarse-grained dislocation densities. The mobilities used in literature on these levels are quite different, for example in terms of their intrinsic the stress dependence. To establish the relation across the scales, we have derived the macroscopic evolution equations of dislocation densities from the equations of motion of individual dislocations by means of systematic coarse-graining. From this, we can identify a memory kernel relating the driving force and the flux of dislocations. This kernel can be considered as an effective macroscopic mobility with two contributions; a direct contribution related to the overdamped motion of individual dislocations, and an emergent contribution that arises from time correlations of fluctuations in the Peach-Koehler force. Scaling analysis shows that the latter contribution is dominant for dislocations in metals at room temperature. We also discuss several concerns related to the separation of timescales.

  7. Coarse atmospheric aerosol: size distributions of trace elements

    NASA Astrophysics Data System (ADS)

    Eleftheriadis, K.; Colbeck, I.

    A sampler, employing nine single stage impactors placed in parallel within a portable wind tunnel, has been used to determine the metal content of coarse atmospheric aerosol. The wind tunnel maintains a constant flow environment for the collectors housed inside it, so that representative sampling conditions are achieved compared to the varied ambient wind conditions. At a flow rate of 8 m s -1 the 50% cut-off diameters of the impactors ranged from 7.8 to 38.8 μm. Measurements were conducted at a rural and urban site near Colchester in south east England. The samplers were analysed by PIXE for P, K, Ca, Fe, Ti, Mn, Cu, V, Co, Cr, Br, Zn, Ni, Sc and Pb. It is found that the sampler can be employed to quantitatively characterise the elemental mass size distribution for aerosol larger than 10 μm. The results indicate that a small fraction of the above earth and trace elements' metal mass is present in particles greater than 10 μm. This fraction for earth metals (Ca, K, Ti) is comparatively greater in the rural site than the urban site, while for trace metals (Mn, V, Cu, Cr) this fraction constitutes a more significant part of the coarse mass at the urban site. Trace element concentrations were of a similar order of magnitude to earlier literature reports. Although the number of measurements was limited it can be concluded that the size distributions obtained were characteristic of an unpolluted area.

  8. A coarse grain model for protein-surface interactions

    NASA Astrophysics Data System (ADS)

    Wei, Shuai; Knotts, Thomas A.

    2013-09-01

    The interaction of proteins with surfaces is important in numerous applications in many fields—such as biotechnology, proteomics, sensors, and medicine—but fundamental understanding of how protein stability and structure are affected by surfaces remains incomplete. Over the last several years, molecular simulation using coarse grain models has yielded significant insights, but the formalisms used to represent the surface interactions have been rudimentary. We present a new model for protein surface interactions that incorporates the chemical specificity of both the surface and the residues comprising the protein in the context of a one-bead-per-residue, coarse grain approach that maintains computational efficiency. The model is parameterized against experimental adsorption energies for multiple model peptides on different types of surfaces. The validity of the model is established by its ability to quantitatively and qualitatively predict the free energy of adsorption and structural changes for multiple biologically-relevant proteins on different surfaces. The validation, done with proteins not used in parameterization, shows that the model produces remarkable agreement between simulation and experiment.

  9. Coarse-grained modeling of RNA 3D structure.

    PubMed

    Dawson, Wayne K; Maciejczyk, Maciej; Jankowska, Elzbieta J; Bujnicki, Janusz M

    2016-07-01

    Functional RNA molecules depend on three-dimensional (3D) structures to carry out their tasks within the cell. Understanding how these molecules interact to carry out their biological roles requires a detailed knowledge of RNA 3D structure and dynamics as well as thermodynamics, which strongly governs the folding of RNA and RNA-RNA interactions as well as a host of other interactions within the cellular environment. Experimental determination of these properties is difficult, and various computational methods have been developed to model the folding of RNA 3D structures and their interactions with other molecules. However, computational methods also have their limitations, especially when the biological effects demand computation of the dynamics beyond a few hundred nanoseconds. For the researcher confronted with such challenges, a more amenable approach is to resort to coarse-grained modeling to reduce the number of data points and computational demand to a more tractable size, while sacrificing as little critical information as possible. This review presents an introduction to the topic of coarse-grained modeling of RNA 3D structures and dynamics, covering both high- and low-resolution strategies. We discuss how physics-based approaches compare with knowledge based methods that rely on databases of information. In the course of this review, we discuss important aspects in the reasoning process behind building different models and the goals and pitfalls that can result.

  10. Coarse-to-fine wavelet-based airport detection

    NASA Astrophysics Data System (ADS)

    Li, Cheng; Wang, Shuigen; Pang, Zhaofeng; Zhao, Baojun

    2015-10-01

    Airport detection on optical remote sensing images has attracted great interest in the applications of military optics scout and traffic control. However, most of the popular techniques for airport detection from optical remote sensing images have three weaknesses: 1) Due to the characteristics of optical images, the detection results are often affected by imaging conditions, like weather situation and imaging distortion; and 2) optical images contain comprehensive information of targets, so that it is difficult for extracting robust features (e.g., intensity and textural information) to represent airport area; 3) the high resolution results in large data volume, which makes real-time processing limited. Most of the previous works mainly focus on solving one of those problems, and thus, the previous methods cannot achieve the balance of performance and complexity. In this paper, we propose a novel coarse-to-fine airport detection framework to solve aforementioned three issues using wavelet coefficients. The framework includes two stages: 1) an efficient wavelet-based feature extraction is adopted for multi-scale textural feature representation, and support vector machine(SVM) is exploited for classifying and coarsely deciding airport candidate region; and then 2) refined line segment detection is used to obtain runway and landing field of airport. Finally, airport recognition is achieved by applying the fine runway positioning to the candidate regions. Experimental results show that the proposed approach outperforms the existing algorithms in terms of detection accuracy and processing efficiency.

  11. Does substrate coarseness matter for foraging ants? An experiment with Lasius niger (Hymenoptera; Formicidae).

    PubMed

    Bernadou, Abel; Fourcassié, Vincent

    2008-03-01

    We investigated whether workers of the ant species Lasius niger are able to sense and discriminate the coarseness of the substrate on which they walk. First, we studied the way in which substrate coarseness affects the ants' locomotory behaviour. Second, we investigated the spontaneous preference of ants for substrates of different coarseness. And third, we tested with a differential conditioning procedure the ants' capacity to learn to associate a given coarseness with a food reward. The locomotory behaviour of ants differed according to substrate coarseness: ants moved significantly faster and had more sinuous trajectories on a fine than on a coarse substrate. No spontaneous preference for a substrate of a given coarseness was observed and, even after 20 successive conditioning trials, there was little evidence of the effect of experience on substrate coarseness discrimination. Overall however, ants trained on fine sand made significantly more correct choice than those trained on coarse sand. We discuss these results and argue that in L. niger substrate coarseness may be more important at the collective level, by interacting with the chemical properties of the pheromone trail used in mass recruitment to food source, than at the individual level.

  12. Fabrication and characterization of TiO2 coated cone shaped nano-fiber pH sensor

    NASA Astrophysics Data System (ADS)

    Pathak, A. K.; Bhardwaj, V.; Gangwar, R. K.; De, M.; Singh, V. K.

    2017-03-01

    In the present paper a novel cone shaped nano-fiber (CSNF) pH sensor using multi-mode fiber (MMF) has been fabricated and demonstrated. Three different pH indicators, chlorophenol red, bromothymol blue and cresol red with precursor tetraethyl orthosilicate (TEOS) have been used for fabrication of pH sensing layer. A significant enhancement in sensing properties of pH sensor with TiO2 thin film has been observed. The pH sensor with TiO2 thin film shows the quite high sensitivity (1.16 dBm/pH) as compared to sensor with simple pH coating (0.81 dBm/pH) at 1550 nm with a good linear response. Moreover, the sensor with TiO2 film exhibits fast response time of ∼ 25 s for pH values ranging from 4 to 11 with excellent stability and durability.

  13. Stimulated Brillouin scattering in highly birefringent multimode tapered chalcogenide photonic crystal fiber for distributed optical sensors (Retraction Notice)

    NASA Astrophysics Data System (ADS)

    Baili, Amira; Cherif, Rim; Zghal, Mourad

    2016-09-01

    This paper, originally published on September 15, 2016, was retracted from the SPIE Digital Library on October 5, 2016, due to a high degree of similarity between specific portions of the text of the paper to the following publications: J. Tchahame, J. Beugnot, A. Kudlinski, and T. Sylvestre, "Multimode Brillouin spectrum in a long tapered birefringent photonic crystal fiber," Opt. Lett. 40, 4281-4284 (2015). doi: 10.1364/OL.40.004281 W. W. Ke, X. J. Wang and X. Tang, "Stimulated Brillouin Scattering Model in Multi-Mode Fiber Lasers," in IEEE Journal of Selected Topics in Quantum Electronics, vol. 20, no. 5, pp. 305-314, Sept.-Oct. 2014. doi: 10.1109/JSTQE.2014.2303256.

  14. Polyimide Fibers

    NASA Technical Reports Server (NTRS)

    St.Clair, Terry L. (Inventor); Fay, Catharine C. (Inventor); Working, Dennis C. (Inventor)

    1997-01-01

    A polyimide fiber having textile physical property characteristics and the process of melt extruding same from a polyimide powder. Polyimide powder formed as the reaction product of the monomers 3.4'-ODA and ODPA, and endcapped with phthalic anhydride to control the molecular weight thereof, is melt extruded in the temperature range of 340? C. to 360? C. and at heights of 100.5 inches, 209 inches and 364.5 inches. The fibers obtained have a diameter in the range of 0.0068 inch to 0.0147 inch; a mean tensile strength in the range of 15.6 to 23.1 ksi; a mean modulus of 406 to 465 ksi; and a mean elongation in the range of 14 to 103%.

  15. Polyimide Fibers

    NASA Technical Reports Server (NTRS)

    St.Clair, Terry L. (Inventor); Fay, Catharine C. (Inventor); Working, Dennis C. (Inventor)

    1998-01-01

    A polyimide fiber having textile physical property characteristics and the process of melt extruding same from a polyimide powder. Polyimide powder formed as the reaction product of the monomers 3.4'-ODA and ODPA, and end- capped with phthalic anhydride to control the molecular weight thereof, is melt extruded in the temperature range of 340 C. to 360 C. and at heights of 100.5 inches. 209 inches and 364.5 inches. The fibers obtained have a diameter in the range of 0.0068 inch to 0.0147 inch; a mean tensile strength in the range of 15.6 to 23.1 ksi; a mean modulus of 406 to 465 ksi, and a mean elongation in the range of 14 to 103%.

  16. Solvation free energies and partition coefficients with the coarse-grained and hybrid all-atom/coarse-grained MARTINI models

    NASA Astrophysics Data System (ADS)

    Genheden, Samuel

    2017-09-01

    We present the estimation of solvation free energies of small solutes in water, n-octanol and hexane using molecular dynamics simulations with two MARTINI models at different resolutions, viz. the coarse-grained (CG) and the hybrid all-atom/coarse-grained (AA/CG) models. From these estimates, we also calculate the water/hexane and water/octanol partition coefficients. More than 150 small, organic molecules were selected from the Minnesota solvation database and parameterized in a semi-automatic fashion. Using either the CG or hybrid AA/CG models, we find considerable deviations between the estimated and experimental solvation free energies in all solvents with mean absolute deviations larger than 10 kJ/mol, although the correlation coefficient is between 0.55 and 0.75 and significant. There is also no difference between the results when using the non-polarizable and polarizable water model, although we identify some improvements when using the polarizable model with the AA/CG solutes. In contrast to the estimated solvation energies, the estimated partition coefficients are generally excellent with both the CG and hybrid AA/CG models, giving mean absolute deviations between 0.67 and 0.90 log units and correlation coefficients larger than 0.85. We analyze the error distribution further and suggest avenues for improvements.

  17. Unconstrained Structure Formation in Coarse-Grained Protein Simulations

    NASA Astrophysics Data System (ADS)

    Bereau, Tristan

    The ability of proteins to fold into well-defined structures forms the basis of a wide variety of biochemical functions in and out of the cell membrane. Many of these processes, however, operate at time- and length-scales that are currently unattainable by all-atom computer simulations. To cope with this difficulty, increasingly more accurate and sophisticated coarse-grained models are currently being developed. In the present thesis, we introduce a solvent-free coarse-grained model for proteins. Proteins are modeled by four beads per amino acid, providing enough backbone resolution to allow for accurate sampling of local conformations. It relies on simple interactions that emphasize structure, such as hydrogen bonds and hydrophobicity. Realistic alpha/beta content is achieved by including an effective nearest-neighbor dipolar interaction. Parameters are tuned to reproduce both local conformations and tertiary structures. By studying both helical and extended conformations we make sure the force field is not biased towards any particular secondary structure. Without any further adjustments or bias a realistic oligopeptide aggregation scenario is observed. The model is subsequently applied to various biophysical problems: (i) kinetics of folding of two model peptides, (ii) large-scale amyloid-beta oligomerization, and (iii) protein folding cooperativity. The last topic---defined by the nature of the finite-size thermodynamic transition exhibited upon folding---was investigated from a microcanonical perspective: the accurate evaluation of the density of states can unambiguously characterize the nature of the transition, unlike its corresponding canonical analysis. Extending the results of lattice simulations and theoretical models, we find that it is the interplay between secondary structure and the loss of non-native tertiary contacts which determines the nature of the transition. Finally, we combine the peptide model with a high-resolution, solvent-free, lipid

  18. Coarse mesh transport theory model for heterogeneous systems

    NASA Astrophysics Data System (ADS)

    Ilas, Danut

    To improve fuel utilization, recent reactor cores have become substantially more heterogeneous. In these cores, use of variable fuel enrichments and strong absorbers lead to high neutron flux gradients, which may limit the accuracy (validity) of diffusion theory based methods. In fact, the diffusion equation itself may become a poor approximation of the Boltzmann equation, the exact equation that describes the neutron flux. Therefore, numerical methods to solve the transport equation efficiently over a large heterogeneous region (such as a reactor core) are very desirable in case where the diffusion approximation breaks down. Presently, the only methods capable of computing the power (flux) distributions very accurately throughout a large system such as a nuclear reactor core are the Monte-Carlo or the fine-mesh transport theory methods. Both these methods suffer from the long computational time which makes them useless for routine core calculations. Starting from a variational principle that admits trial functions that can be discontinuous at coarse mesh (assembly) interfaces, we propose a method to solve the transport equation on a spatial grid made up of meshes as large as the size of a fuel assembly. The variational principle is derived for the most general case, but further methods are developed for one-dimensional geometry with the angular variable treated by discrete ordinates. The method uses the finite element approach for the space variable with basis functions precomputed for each element to obtain an algebraic linear system of equations. The eigenvalue of this system is the multiplication constant and the eigenvector represents the incoming angular fluxes for each coarse mesh. The latter allows the reconstruction of the fine mesh solution (angular flux) throughout the domain of interest when used with the basis functions (surface Green's function) for each coarse mesh. The method requires no homogenization procedure that can be a serious source of

  19. A coarse grained stochastic particle interacting system for tropical convection

    NASA Astrophysics Data System (ADS)

    Khouider, B.

    2012-12-01

    Climate models (GCMs) fail to represent adequately the variability associated with organized convection in the tropics. This deficiency is believed to hinder medium and long range weather forecasts, over weeks to months. GCMs use very complex sub-grid models, known as cumulus parameterizations, to represent the effects of clouds and convection as well as other unresolved processes. Cumulus parameterizations are intrinsically deterministic and are typically based on the quasi-equilibrium theory, which assumes that convection instantaneously consumes the atmospheric instability produced by radiation. In this talk, I will discuss a stochastic model for organized tropical convection based on a particle interacting system defined on a microscopic lattice. An order parameter is assumed to take the values 0,1,2,3 at a any given lattice site according to whether it is a clear site or it is occupied by a cloud of a one of the three types: congestus, deep, or stratiform, following intuitive rules motivated by recent satellite observations and various field campaigns conducted over the Indian Ocean and Western Pacific. The microscopic Markov process is coarse-grained systematically to obtain a multidimensional birth-death process with immigration, following earlier work done by Katsoulakis, Majda, and Vlachos (JCP 2003) for the case of the Ising model where the order parameter takes the values 0 and 1. The coarse grained birth-death process is a stochastic model, intermediate between the microscopic lattice model and the deterministic mean field limit, that is used to represent the sub-grid scale variability of the underlying physical process (here the cloud cover) with a negligible computational overhead and yet permits both local interactions between lattice sites and two-way interactions between the cloud cover and the large-scale climate dynamics. The new systematic coarse-graining, developed here for the multivalued order parameter, provides a unifying framework

  20. Forced unraveling of chromatin fibers with nonuniform linker DNA lengths

    NASA Astrophysics Data System (ADS)

    Ozer, Gungor; Collepardo-Guevara, Rosana; Schlick, Tamar

    2015-02-01

    The chromatin fiber undergoes significant structural changes during the cell's life cycle to modulate DNA accessibility. Detailed mechanisms of such structural transformations of chromatin fibers as affected by various internal and external conditions such as the ionic conditions of the medium, the linker DNA length, and the presence of linker histones, constitute an open challenge. Here we utilize Monte Carlo (MC) simulations of a coarse grained model of chromatin with nonuniform linker DNA lengths as found in vivo to help explain some aspects of this challenge. We investigate the unfolding mechanisms of chromatin fibers with alternating linker lengths of 26-62 bp and 44-79 bp using a series of end-to-end stretching trajectories with and without linker histones and compare results to uniform-linker-length fibers. We find that linker histones increase overall resistance of nonuniform fibers and lead to fiber unfolding with superbeads-on-a-string cluster transitions. Chromatin fibers with nonuniform linker DNA lengths display a more complex, multi-step yet smoother process of unfolding compared to their uniform counterparts, likely due to the existence of a more continuous range of nucleosome-nucleosome interactions. This finding echoes the theme that some heterogeneity in fiber component is biologically advantageous.

  1. Nucleosome geometry and internucleosomal interactions control the chromatin fiber conformation.

    PubMed

    Kepper, Nick; Foethke, Dietrich; Stehr, Rene; Wedemann, Gero; Rippe, Karsten

    2008-10-01

    Based on model structures with atomic resolution, a coarse-grained model for the nucleosome geometry was implemented. The dependence of the chromatin fiber conformation on the spatial orientation of nucleosomes and the path and length of the linker DNA was systematically explored by Monte Carlo simulations. Two fiber types were analyzed in detail that represent nucleosome chains without and with linker histones, respectively: two-start helices with crossed-linker DNA (CL conformation) and interdigitated one-start helices (ID conformation) with different nucleosome tilt angles. The CL conformation was derived from a tetranucleosome crystal structure that was extended into a fiber. At thermal equilibrium, the fiber shape persisted but relaxed into a structure with a somewhat lower linear mass density of 3.1 +/- 0.1 nucleosomes/11 nm fiber. Stable ID fibers required local nucleosome tilt angles between 40 degrees and 60 degrees. For these configurations, much higher mass densities of up to 7.9 +/- 0.2 nucleosomes/11 nm fiber were obtained. A model is proposed, in which the transition between a CL and ID fiber is mediated by relatively small changes of the local nucleosome geometry. These were found to be in very good agreement with changes induced by linker histone H1 binding as predicted from the high resolution model structures.

  2. Multi-Mode Cavity Accelerator Structure

    SciTech Connect

    Jiang, Yong; Hirshfield, Jay Leonard

    2016-11-10

    This project aimed to develop a prototype for a novel accelerator structure comprising coupled cavities that are tuned to support modes with harmonically-related eigenfrequencies, with the goal of reaching an acceleration gradient >200 MeV/m and a breakdown rate <10-7/pulse/meter. Phase I involved computations, design, and preliminary engineering of a prototype multi-harmonic cavity accelerator structure; plus tests of a bimodal cavity. A computational procedure was used to design an optimized profile for a bimodal cavity with high shunt impedance and low surface fields to maximize the reduction in temperature rise ΔT. This cavity supports the TM010 mode and its 2nd harmonic TM011 mode. Its fundamental frequency is at 12 GHz, to benchmark against the empirical criteria proposed within the worldwide High Gradient collaboration for X-band copper structures; namely, a surface electric field Esurmax< 260 MV/m and pulsed surface heating ΔTmax< 56 °K. With optimized geometry, amplitude and relative phase of the two modes, reductions are found in surface pulsed heating, modified Poynting vector, and total RF power—as compared with operation at the same acceleration gradient using only the fundamental mode.

  3. Multi-mode radio frequency device

    DOEpatents

    Gilbert, Ronald W.; Carrender, Curtis Lee; Anderson, Gordon A.; Steele, Kerry D.

    2007-02-13

    A transponder device having multiple modes of operation, such as an active mode and a passive mode, wherein the modes of operation are selected in response to the strength of a received radio frequency signal. A communication system is also provided having a transceiver configured to transmit a radio frequency signal and to receive a responsive signal, and a transponder configured to operate in a plurality of modes and to activate modes of operation in response to the radio frequency signal. Ideally, each mode of operation is activated and deactivated independent of the other modes, although two or more modes may be concurrently operational.

  4. Multi-mode modem/codec designs

    NASA Technical Reports Server (NTRS)

    Osborne, William; Carden, Frank; Kopp, Brian; Ross, Mike

    1992-01-01

    The design of an integrated modem/codec unit which can receive coded and uncoded BPSK an QPSK using de facto standard coding schemes as well as 8PSK-TCM and 16PSK-TCM is examined. The design is totally compatible with today's modulation schemes and capable of processing tomorrow's TCM codes. This is accomplished in the modem by using quadrature channel carrier recovery processing and a version of the MAP phase detector algorithm. The symbol synchronization is accomplished with a derivative of an early-late gate designed to accommodate multilevel signals.

  5. Multi-mode horn antenna simulation

    NASA Technical Reports Server (NTRS)

    Dod, L. R.; Wolf, J. D.

    1980-01-01

    Radiation patterns were computed for a circular multimode horn antenna using waveguide electric field radiation expressions. The circular multimode horn was considered as a possible reflector feed antenna for the Large Antenna Multifrequency Microwave Radiometer (LAMMR). This horn antenna uses a summation of the TE sub 11 deg and TM sub 11 deg modes to generate far field primary radiation patterns with equal E and H plane beamwidths and low sidelobes. A computer program for the radiation field expressions using the summation of waveguide radiation modes is described. The sensitivity of the multimode horn antenna radiation patterns to phase variations between the two modes is given. Sample radiation pattern calculations for a reflector feed horn for LAMMR are shown. The multimode horn antenna provides a low noise feed suitable for radiometric applications.

  6. Fine and coarse dust separation with polarization lidar

    NASA Astrophysics Data System (ADS)

    Mamouri, R. E.; Ansmann, A.

    2014-11-01

    The polarization-lidar photometer networking (POLIPHON) method for separating dust and non-dust aerosol backscatter and extinction, volume, and mass concentration is extended to allow for a height-resolved separation of fine-mode and coarse-mode dust properties in addition. The method is applied to a period with complex aerosol layering of fine-mode background dust from Turkey and Arabian desert dust from Syria. The observation was performed at the combined European Aerosol Research Lidar Network (EARLINET) and Aerosol Robotic Network (AERONET) site of Limassol (34.7° N, 33° E), Cyprus, in September 2011. The dust profiling methodology and case studies are presented. Consistency between the column-integrated optical properties obtained with sun/sky photometer and the respective results derived by means of the new lidar-based method corroborate the applicability of the extended POLIPHON version.

  7. MARTINI Coarse-Grained Models of Polyethylene and Polypropylene.

    PubMed

    Panizon, Emanuele; Bochicchio, Davide; Monticelli, Luca; Rossi, Giulia

    2015-06-25

    The understanding of the interaction of nanoplastics with living organisms is crucial both to assess the health hazards of degraded plastics and to design functional polymer nanoparticles with biomedical applications. In this paper, we develop two coarse-grained models of everyday use polymers, polyethylene (PE) and polypropylene (PP), aimed at the study of the interaction of hydrophobic plastics with lipid membranes. The models are compatible with the popular MARTINI force field for lipids, and they are developed using both structural and thermodynamic properties as targets in the parametrization. The models are then validated by showing their reliability at reproducing structural properties of the polymers, both linear and branched, in dilute conditions, in the melt, and in a PE-PP blend. PE and PP radius of gyration is correctly reproduced in all conditions, while PE-PP interactions in the blend are slightly overestimated. Partitioning of PP and PE oligomers in phosphatidylcholine membranes as obtained at CG level reproduces well atomistic data.

  8. The Apollo 15 coarse fines (4-10 mm)

    NASA Technical Reports Server (NTRS)

    Ryder, Graham; Sherman, Sarah Bean

    1989-01-01

    A new catalog of the Apollo 15 coarse fines particles is presented. Powell's macroscopic descriptions, resulting from his 1972 particle by particle binocular examination of all of the Apollo 15 4 to 10 mm fines samples, are retained. His groupings are also retained, but petrographic, chemical, and other data from later analyses are incorporated into this catalog to better characterize individual particles and describe the groups. A large number of particles have no characterization beyond that done by Powell. Complete descriptions of the particles and all known references are provided. The catalog is intended for anyone interested in the rock types collected by Dave Scott and Jim Irwin in the Hadley-Appenine region, and particularly for researchers requiring sample allocations.

  9. Coarse-to-fine three-dimensional digitization system

    NASA Astrophysics Data System (ADS)

    Daval, Vincent; Truchetet, Frederic; Aubreton, Olivier

    2015-11-01

    The three-dimensional (3-D) workflow (acquisition-processing-compression) is, in most cases, sequenced into several independent steps. Such approaches result in an acquisition of an important number of 3-D points. After acquisition, the first processing step is a simplification of the data by suppressing many of the computed points. We propose a coarse-to-fine acquisition system that makes it possible to obtain simplified data directly from the acquisition. By calculating some complementary information from two-dimensional (2-D) images, such as 3-D normals, multiple-homogeneous regions will be segmented and affected for a given primitive class. In contrast to other studies, the whole process is not based on a mesh. The obtained model is simplified directly from the 2-D data acquired by a 3-D scanner.

  10. A Coarse-Grained Model for Simulating Chitosan Hydrogels

    NASA Astrophysics Data System (ADS)

    Xu, Hongcheng; Matysiak, Silvina

    Hydrogels are biologically-derived materials composed of water-filled cross-linking polymer chains. It has widely been used as biodegradable material and has many applications in medical devices. The chitosan hydrogel is stimuli-responsive for undergoing pH-sensitive self-assembly process, allowing programmable tuning of the chitosan deposition through electric pulse. To explore the self-assembly mechanism of chitosan hydroge, we have developed an explicit-solvent coarse-grained chitosan model that has roots in the MARTINI force field, and the pH change is modeled by protonating chitosan chains using the Henderson-Hasselbalch equation. The mechanism of hydrogel network formation will be presented. The self-assembled polymer network qualitatively reproduce many experimental observables such as the pH-dependent strain-stress curve, bulk moduli, and structure factor. Our model is also capable of simulating other similar polyelectrolyte polymer systems.

  11. Coarse-fine residual gravity cancellation system with magnetic levitation

    NASA Technical Reports Server (NTRS)

    Salcudean, S. E.; Davis, H.; Chen, C. T.; Goertz, D. E.; Tryggvason, B. V.

    1992-01-01

    Aircraft flight along parabolic trajectories have been proposed and executed in order to achieve low cost, near free fall conditions of moderate duration. This paper describes a six degree of freedom experiment isolation system designed to cancel out residual accelerations due to mechanical vibrations and errors in aircraft trajectory. The isolation system consists of a fine motion magnetic levitator whose stator is transported by a conventional coarse motion stage. The levitator uses wide gap voice coil actuators and has the dual purpose of isolating the experiment platform from aircraft vibrations and actively cancelling residual accelerations through feedback control. The course motion stage tracks the levitated platform in order to keep the levitator's coils centered within their matching magnetic gaps. Aspects of system design, an analysis of the proposed control strategy and simulation results are presented. Feasibility experiments are also discussed.

  12. Coarse-grained theory of a realistic tetrahedral liquid model

    NASA Astrophysics Data System (ADS)

    Procaccia, I.; Regev, I.

    2012-02-01

    Tetrahedral liquids such as water and silica-melt show unusual thermodynamic behavior such as a density maximum and an increase in specific heat when cooled to low temperatures. Previous work had shown that Monte Carlo and mean-field solutions of a lattice model can exhibit these anomalous properties with or without a phase transition, depending on the values of the different terms in the Hamiltonian. Here we use a somewhat different approach, where we start from a very popular empirical model of tetrahedral liquids —the Stillinger-Weber model— and construct a coarse-grained theory which directly quantifies the local structure of the liquid as a function of volume and temperature. We compare the theory to molecular-dynamics simulations and show that the theory can rationalize the simulation results and the anomalous behavior.

  13. Predicting the settlement of coarse granular materials under vertical loading.

    PubMed

    Quezada, Juan Carlos; Saussine, Gilles; Breul, Pierre; Radjaï, Farhang

    2014-07-16

    Granular materials are widely used in industrial processes despite their complex and poorly understood mechanical behaviour both in static and dynamic regimes. A prototypical example is the settlement and compaction of a granular bed under vibrational loading. The elementary mechanisms of this process are still unclear and there is presently no established theory or methodology to predict the settlement and its statistical variability. By means of a parametric study, carried out on a full-scale track, and a critical analysis of density relaxation laws, we introduce a novel settlement model in coarse granular materials under cyclic loading. Our extensive experimental data indicate that the settlement process is governed by three independent parameters strongly correlated with the vibration intensity and initial packing fraction. We show that the mean settlement is well predicted by the model with its parameter values extracted from experimental data.

  14. Granular mechanics of the critical state of coarse soils

    NASA Astrophysics Data System (ADS)

    Yanqui, Calixtro

    2013-06-01

    In this paper, coarse soils are modeled by granular packings, because both of them have similar characteristics, such as: gaseousity, duality, dilatancy, fragility and hyperbolicity. By virtue of these properties, it is assumed that the contact force ensemble remains the same, while the packing changes because of its dual character, regarding the compactness of the soil. For the dense state, both assemblages coincide themselves, forming chains of contact forces; the transmission of stresses obeys the Trollope's hypothesis of centroidal reactions; and the volumetric strain increases. For the loose state, the packing adopts a "passive" distribution, yielding a constant angle of internal friction at failure; so that, the strain is contractive and the stress transmission occurs fundamentally by shear, in a similar fashion to the Rowe's mechanism. In the figures, the good correspondence between the results of the theory and the reported experimental data is shown.

  15. Sequence transferable coarse-grained model of amphiphilic copolymers

    NASA Astrophysics Data System (ADS)

    De Silva, Chathuranga C.; Leophairatana, Porakrit; Ohkuma, Takahiro; Koberstein, Jeffrey T.; Kremer, Kurt; Mukherji, Debashish

    2017-08-01

    Polymer properties are inherently multi-scale in nature, where delicate local interaction details play a key role in describing their global conformational behavior. In this context, deriving coarse-grained (CG) multi-scale models for polymeric liquids is a non-trivial task. Further complexities arise when dealing with copolymer systems with varying microscopic sequences, especially when they are of amphiphilic nature. In this work, we derive a segment-based generic CG model for amphiphilic copolymers consisting of repeat units of hydrophobic (methylene) and hydrophilic (ethylene oxide) monomers. The system is a simulation analogue of polyacetal copolymers [S. Samanta et al., Macromolecules 49, 1858 (2016)]. The CG model is found to be transferable over a wide range of copolymer sequences and also to be consistent with existing experimental data.

  16. Coarse-graining RNA nanostructures for molecular dynamics simulations

    PubMed Central

    Paliy, Maxim; Melnik, Roderick; Shapiro, Bruce A

    2013-01-01

    A series of coarse-grained models have been developed for study of the molecular dynamics of RNA nanostructures. The models in the series have one to three beads per nucleotide and include different amounts of detailed structural information. Such a treatment allows us to reach, for systems of thousands of nucleotides, a time scale of microseconds (i.e. by three orders of magnitude longer than in full atomistic modeling) and thus to enable simulations of large RNA polymers in the context of bionanotechnology. We find that the three-beads-per-nucleotide models, described by a set of just a few universal parameters, are able to describe different RNA conformations and are comparable in structural precision to the models where detailed values of the backbone P-C4′ dihedrals taken from a reference structure are included. These findings are discussed in the context of RNA conformation classes. PMID:20577037

  17. Coarse grained modeling of transport properties in monoclonal antibody solution

    NASA Astrophysics Data System (ADS)

    Swan, James; Wang, Gang

    Monoclonal antibodies and their derivatives represent the fastest growing segment of the bio pharmaceutical industry. For many applications such as novel cancer therapies, high concentration, sub-cutaneous injections of these protein solutions are desired. However, depending on the peptide sequence within the antibody, such high concentration formulations can be too viscous to inject via human derived force alone. Understanding how heterogenous charge distribution and hydrophobicity within the antibodies leads to high viscosities is crucial to their future application. In this talk, we explore a coarse grained computational model of therapeutically relevant monoclonal antibodies that accounts for electrostatic, dispersion and hydrodynamic interactions between suspended antibodies to predict assembly and transport properties in concentrated antibody solutions. We explain the high viscosities observed in many experimental studies of the same biologics.

  18. One-bead coarse-grained model for RNA dynamics.

    PubMed

    Villada-Balbuena, Mario; Carbajal-Tinoco, Mauricio D

    2017-01-28

    We present a revised version of a coarse-grained model for RNA dynamics. In such approach, the description of nucleotides is reduced to single points that interact between them through a series of effective pair potentials that were obtained from an improved analysis of RNA structures from the Protein Data Bank. These interaction potentials are the main constituents of a Brownian dynamics simulation algorithm that allows to perform a variety of tasks by taking advantage of the reduced number of variables. Such tasks include the prediction of the three-dimensional configuration of a series of test molecules. Moreover, the model permits the inclusion of effective magnesium ions and the ends of the RNA chains can be pulled with an external force to study the process of unfolding. In spite of the simplicity of the model, we obtain a good agreement with the experimental results.

  19. Predicting the settlement of coarse granular materials under vertical loading

    NASA Astrophysics Data System (ADS)

    Quezada, Juan Carlos; Saussine, Gilles; Breul, Pierre; Radjaï, Farhang

    2014-07-01

    Granular materials are widely used in industrial processes despite their complex and poorly understood mechanical behaviour both in static and dynamic regimes. A prototypical example is the settlement and compaction of a granular bed under vibrational loading. The elementary mechanisms of this process are still unclear and there is presently no established theory or methodology to predict the settlement and its statistical variability. By means of a parametric study, carried out on a full-scale track, and a critical analysis of density relaxation laws, we introduce a novel settlement model in coarse granular materials under cyclic loading. Our extensive experimental data indicate that the settlement process is governed by three independent parameters strongly correlated with the vibration intensity and initial packing fraction. We show that the mean settlement is well predicted by the model with its parameter values extracted from experimental data.

  20. Biomembranes in atomistic and coarse-grained simulations

    NASA Astrophysics Data System (ADS)

    Pluhackova, Kristyna; Böckmann, Rainer A.

    2015-08-01

    The architecture of biological membranes is tightly coupled to the localization, organization, and function of membrane proteins. The organelle-specific distribution of lipids allows for the formation of functional microdomains (also called rafts) that facilitate the segregation and aggregation of membrane proteins and thus shape their function. Molecular dynamics simulations enable to directly access the formation, structure, and dynamics of membrane microdomains at the molecular scale and the specific interactions among lipids and proteins on timescales from picoseconds to microseconds. This review focuses on the latest developments of biomembrane force fields for both atomistic and coarse-grained molecular dynamics (MD) simulations, and the different levels of coarsening of biomolecular structures. It also briefly introduces scale-bridging methods applicable to biomembrane studies, and highlights selected recent applications.

  1. A Novel Demultiplexing Design for Coarse WDM: Exploiting Material Dispersion

    NASA Astrophysics Data System (ADS)

    Salameh, Haythem Bany; Al-Rabaie, Mohammad; Khreishah, Abdallah; Al-Zubi, Raed

    2017-08-01

    In this paper, a compact low-cost simple-to-fabricate demultiplexer is proposed for coarse wavelength division multiplexing (CWDM). The device consists of two layers of the same semiconductor material: the first layer is homogeneous medium with a given refractive index n_2, while the second layer is an inhomogeneous medium, where its refractive index is graded according to a creation profile. The proposed design exploits the ray's spatial shift that results from material dispersion as difference wavelengths propagate through the structure. Through analytical analysis and numerical evaluation, we investigate the effects of the various design parameters on the amount of achieved spatial shift between the adjacent wavelengths and the size of the device. The results show promising results for four- and eight-channel devices operating on the standard CWDM wavelength grid.

  2. One-bead coarse-grained model for RNA dynamics

    NASA Astrophysics Data System (ADS)

    Villada-Balbuena, Mario; Carbajal-Tinoco, Mauricio D.

    2017-01-01

    We present a revised version of a coarse-grained model for RNA dynamics. In such approach, the description of nucleotides is reduced to single points that interact between them through a series of effective pair potentials that were obtained from an improved analysis of RNA structures from the Protein Data Bank. These interaction potentials are the main constituents of a Brownian dynamics simulation algorithm that allows to perform a variety of tasks by taking advantage of the reduced number of variables. Such tasks include the prediction of the three-dimensional configuration of a series of test molecules. Moreover, the model permits the inclusion of effective magnesium ions and the ends of the RNA chains can be pulled with an external force to study the process of unfolding. In spite of the simplicity of the model, we obtain a good agreement with the experimental results.

  3. Acceleration of coarse grain molecular dynamics on GPU architectures.

    PubMed

    Shkurti, Ardita; Orsi, Mario; Macii, Enrico; Ficarra, Elisa; Acquaviva, Andrea

    2013-04-05

    Coarse grain (CG) molecular models have been proposed to simulate complex systems with lower computational overheads and longer timescales with respect to atomistic level models. However, their acceleration on parallel architectures such as graphic processing units (GPUs) presents original challenges that must be carefully evaluated. The objective of this work is to characterize the impact of CG model features on parallel simulation performance. To achieve this, we implemented a GPU-accelerated version of a CG molecular dynamics simulator, to which we applied specific optimizations for CG models, such as dedicated data structures to handle different bead type interactions, obtaining a maximum speed-up of 14 on the NVIDIA GTX480 GPU with Fermi architecture. We provide a complete characterization and evaluation of algorithmic and simulated system features of CG models impacting the achievable speed-up and accuracy of results, using three different GPU architectures as case studies. Copyright © 2012 Wiley Periodicals, Inc.

  4. Variational coarse-graining procedure for dynamic homogenization

    NASA Astrophysics Data System (ADS)

    Liu, Chenchen; Reina, Celia

    2017-07-01

    We present a variational coarse-graining framework for heterogeneous media in the spirit of FE2 methods, that allows for a seamless transition from the traditional static scenario to dynamic loading conditions, while being applicable to general material behavior as well as to discrete or continuous representations of the material and its deformation, e.g., finite element discretizations or atomistic systems. The method automatically delivers the macroscopic equations of motion together with the generalization of Hill's averaging relations to the dynamic setting. These include the expression of the macroscopic stresses and linear momentum as a function of the microscopic fields. We further demonstrate with a proof of concept example, that the proposed theoretical framework can be used to perform multiscale numerical simulations. The results are compared with standard single-scale finite element simulations, showcasing the capability of the method to capture the dispersive nature of the medium in the range of frequencies permitted by the multiscale strategy.

  5. Coarse-grained kinetic equations for quantum systems

    NASA Astrophysics Data System (ADS)

    Petrov, E. G.

    2013-01-01

    The nonequilibrium density matrix method is employed to derive a master equation for the averaged state populations of an open quantum system subjected to an external high frequency stochastic field. It is shown that if the characteristic time τstoch of the stochastic process is much lower than the characteristic time τsteady of the establishment of the system steady state populations, then on the time scale Δ t ˜ τsteady, the evolution of the system populations can be described by the coarse-grained kinetic equations with the averaged transition rates. As an example, the exact averaging is carried out for the dichotomous Markov process of the kangaroo type.

  6. Wavelength-agile high-power sources via four-wave mixing in higher-order fiber modes.

    PubMed

    Demas, J; Prabhakar, G; He, T; Ramachandran, S

    2017-04-03

    Frequency doubling of conventional fiber lasers in the near-infrared remains the most promising method for generating integrated high-peak-power lasers in the visible, while maintaining the benefits of a fiber geometry; but since the shortest wavelength power-scalable fiber laser sources are currently restricted to either the 10XX nm or 15XX nm wavelength ranges, accessing colors other than green or red remains a challenge with this schematic. Four-wave mixing using higher-order fiber modes allows for control of dispersion while maintaining large effective areas, thus enabling a power-scalable method to extend the bandwidth of near-infrared fiber lasers, and in turn, the bandwidth of potential high-power sources in the visible. Here, two parametric sources using the LP0,7 and LP0,6 modes of two step-index multi-mode fibers are presented. The output wavelengths for the sources are 880, 974, 1173, and 1347 nm with peak powers of 10.0, 16.2, 14.7, and 6.4 kW respectively, and ~300-ps pulse durations. The efficiencies of the sources are analyzed, along with a discussion of wavelength tuning and further power scaling, representing an advance in increasing the bandwidth of near-infrared lasers as a step towards high-peak-power sources at wavelengths across the visible spectrum.

  7. Changes in speckle patterns induced by load application onto an optical fiber and its possible application for sensing purpose

    NASA Astrophysics Data System (ADS)

    Hasegawa, Makoto; Okumura, Jyun-ya; Hyuga, Akio

    2015-08-01

    Speckle patterns to be observed in an output light spot from an optical fiber are known to be changed due to external disturbances applied onto the optical fiber. In order to investigate possibilities of utilizing such changes in speckle patterns for sensing application, a certain load was applied onto a jacket-covered communication-grade multi-mode glass optical fiber through which laser beams emitted from a laser diode were propagating, and observed changes in speckle patterns in the output light spot from the optical fiber were investigated both as image data via a CCD camera and as an output voltage from a photovoltaic panel irradiated with the output light spot. The load was applied via a load application mechanism in which several ridges were provided onto opposite flat plates and a certain number of weights were placed there so that corrugated bending of the optical fiber was intentionally induced via load application due to the ridges. The obtained results showed that the number of speckles in the observed pattern in the output light spot as well as the output voltage from the photovoltaic panel irradiated with the output light spot showed decreases upon load application with relatively satisfactory repeatability. When the load was reduced, i.e., the weights were removed, the number of speckles then showed recovery. These results indicate there is a certain possibility of utilizing changes in speckle patterns for sensing of load application onto the optical fiber.

  8. Application of phased array techniques to coarse grain components inspection.

    PubMed

    Mahaut, Steve; Godefroit, Jean-Louis; Roy, Olivier; Cattiaux, Gérard

    2004-04-01

    Ultrasonic inspection of cast stainless steel components from primary and auxiliary cooling circuits of French Nuclear Power Plant has to face with major difficulties due to the coarse grained structure of these materials. Attenuation losses and structural noise are encountered, which limits the performances of defect detection ability, mostly in terms of degraded signal-to-noise ratio and poor sensitivity. To overcome such problems, theoretical and experimental studies have been achieved at the French Atomic Energy Commission, with support from the French Institute for Radiological Protection and Nuclear Safety. Experimental studies have been performed over stainless steel specimen of known coarse structure (equiaxial grains and/or elongated grains), containing artificial reflectors (cylindrical holes and electro-eroded surface breaking notches). Those mock-ups have been inspected using contact probes of different array designs (linear or matrix splitting), and using pulse echo or dual-element techniques. Such arrays allow to control the ultrasonic beam so as to investigate different inspection angles and focusing depths. Experiments were carried out using oblique longitudinal waves, using delay laws computed by a specific model, taking account of acoustical and geometrical properties of the probes and the inspected component. In addition, specific reconstruction techniques have been investigated to enhance the signal-to-noise ratio as well as spatial resolution. These techniques are based on beam-forming summation and multi-angle inspections. Experimental results show that such techniques allow to reduce the speckle noise and to optimise the beam resolution. Those increased performances allow to detect and to size small planar defects located at the inner wall of a thick specimen, using corner and tip diffraction echoes.

  9. Mesoscopic coarse-grained simulations of lysozyme adsorption.

    PubMed

    Yu, Gaobo; Liu, Jie; Zhou, Jian

    2014-05-01

    Coarse-grained simulations are adopted to study the adsorption behavior of lysozyme on different (hydrophobic, neutral hydrophilic, zwitterionic, negatively charged, and positively charged) surfaces at the mesoscopic microsecond time scale (1.2 μs). Simulation results indicate the following: (i) the conformation change of lysozyme on the hydrophobic surface is bigger than any other studied surfaces; (ii) the active sites of lysozyme are faced to the hydrophobic surface with a "top end-on" orientation, while they are exposed to the liquid phase on the hydrophilic surface with a "back-on" orientation; (iii) the neutral hydrophilic surface can induce the adsorption of lysozyme, while the nonspecific protein adsorption can be resisted by the zwitterionic surface; (iv) when the solution ionic strength is low, lysozyme can anchor on the negatively charged surface easily but cannot adsorb on the positively charged surface; (v) when the solution ionic strength is high, the positively charged lysozyme can also adsorb on the like-charged surface; (vi) the major positive potential center of lysozyme, especially the residue ARG128, plays a vital role in leading the adsorption of lysozyme on charged surfaces; (vii) when the ionic strength is high, a counterion layer is formed above the positively charged surface, which is the key factor why lysozyme can adsorb on a like-charged surface. The coarse-grained method based on the MARTINI force field for proteins and the BMW water model could provide an efficient way to understand protein interfacial adsorption behavior at a greater length scale and time scale.

  10. Relative entropy and optimization-driven coarse-graining methods in VOTCA

    SciTech Connect

    Mashayak, S. Y.; Jochum, Mara N.; Koschke, Konstantin; Aluru, N. R.; Rühle, Victor; Junghans, Christoph; Huang, Xuhui

    2015-07-20

    We discuss recent advances of the VOTCA package for systematic coarse-graining. Two methods have been implemented, namely the downhill simplex optimization and the relative entropy minimization. We illustrate the new methods by coarse-graining SPC/E bulk water and more complex water-methanol mixture systems. The CG potentials obtained from both methods are then evaluated by comparing the pair distributions from the coarse-grained to the reference atomistic simulations.We have also added a parallel analysis framework to improve the computational efficiency of the coarse-graining process.

  11. Relative Entropy and Optimization-Driven Coarse-Graining Methods in VOTCA

    PubMed Central

    Mashayak, S. Y.; Jochum, Mara N.; Koschke, Konstantin; Aluru, N. R.; Rühle, Victor; Junghans, Christoph

    2015-01-01

    We discuss recent advances of the VOTCA package for systematic coarse-graining. Two methods have been implemented, namely the downhill simplex optimization and the relative entropy minimization. We illustrate the new methods by coarse-graining SPC/E bulk water and more complex water-methanol mixture systems. The CG potentials obtained from both methods are then evaluated by comparing the pair distributions from the coarse-grained to the reference atomistic simulations. In addition to the newly implemented methods, we have also added a parallel analysis framework to improve the computational efficiency of the coarse-graining process. PMID:26192992

  12. Importance of Coarse Woody Debris to Avian Communities in Loblolly Pine Forests

    SciTech Connect

    Lohr, S.M.; Gauthreaux, S.A.; Kilgo, J.C.

    2001-06-14

    Investigates the importance of standing and down coarse woody debris to bird communities in loblolly pine forests, researchers compared breeding and nonbreeding responses of birds among two coarse woody debris removal and control treatments. Quantification of vegetation layers to determine their effects on the experimental outcome coarse woody debris removal had no effect on the nonbreeding bird community. Most breeding and nonbreeding species used habitats with sparse midstory and well-developed understory, where as sparse canopy cover and dense midstory were important to some nonbreeding species. Snag and down coarse woody debris practices that maintain a dense understory, sparse midstory and canopy will create favorable breeding habitat.

  13. Coarse-grained computer simulation of dynamics in thylakoid membranes: methods and opportunities

    PubMed Central

    Schneider, Anna R.; Geissler, Phillip L.

    2013-01-01

    Coarse-grained simulation is a powerful and well-established suite of computational methods for studying structure and dynamics in nanoscale biophysical systems. As our understanding of the plant photosynthetic apparatus has become increasingly nuanced, opportunities have arisen for coarse-grained simulation to complement experiment by testing hypotheses and making predictions. Here, we give an overview of best practices in coarse-grained simulation, with a focus on techniques and results that are applicable to the plant thylakoid membrane–protein system. We also discuss current research topics for which coarse-grained simulation has the potential to play a key role in advancing the field. PMID:24478781

  14. Coarse-fine adaptive tuned vibration absorber with high frequency resolution

    NASA Astrophysics Data System (ADS)

    Wang, Xi; Yang, Bintang; You, Jiaxin; Gao, Zhe

    2016-11-01

    The speed fluctuation of satellite-rotary-mechanisms causes vibration of slightly different frequencies. The critical requirements of satellites need a vibration control device with high frequency resolution to suppress the vibration. This paper presents a coarse-fine adaptive tuned vibration absorber (ATVA) with high frequency resolution. The coarse-fine ATVA which simultaneously satisfies the requirements of high resolution and relatively wide effective bandwidth is capable of tracking the variable exciting frequency adaptively to suppress the vibration of the primary system. The coarse-fine ATVA is divided into a coarse tuning segment and a fine tuning segment. The coarse tuning segment is used to tune the required natural frequency in a relatively wide effective bandwidth and the fine tuning segment can achieve precise tune in a tiny-scale bandwidth. The mathematical model of the coarse tuning and the fine tuning is proposed to design the parameters of the coarse-fine ATVA. The experimental test results indicate the coarse tuning bandwidth of the coarse-fine ATVA is 8.7 Hz to 29 Hz and the minimum resolution of the fine tuning is 0.05 Hz. Moreover, a significant vibration attenuation of 15dB is verified in the effective bandwidth.

  15. Micromechanics Solution for the Elastic Moduli of Fiber-Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Huan, Yu Jia; Yang, Liu; Jin, Yu; Guang, Jia Lian; Ming, Liu

    2014-09-01

    The overall elastic moduli of fiber-reinforced concrete composite materials are investigated by employing the theory of micromechanics. A method based on the Mori-Tanaka theory and triple inhomogeneities is found to provide a sufficiently accurate evaluation of the average elastic properties of fiber-reinforced concrete composite materials. The inhomogeneities of the materials are divided into three groups: a fine aggregate, a coarse aggregate, and fibers (steel or polymer). The elastic moduli of fiber-reinforced concrete composite materials are determined as functions of the physical properties and volume fraction of sand, gravel, fibers (steel or polymer), and cement paste as a matrix. The theoretical results obtained are compared with published experimental data. The parameters affecting the elastic moduli of fiber-reinforced concrete are discussed in detail.

  16. Long-period grating and its cascaded counterpart in photonic crystal fiber for gas phase measurement.

    PubMed

    Tian, Fei; Kanka, Jiri; Du, Henry

    2012-09-10

    Regular and cascaded long period gratings (LPG, C-LPG) of periods ranging from 460 to 590 μm were inscribed in an endlessly single mode photonic crystal fiber (PCF) using CO(2) laser for sensing measurements of helium, argon and acetylene. High index sensitivities in excess of 1700 nm/RIU were achieved in both grating schemes with a period of 460 μm. The sharp interference fringes in the transmission spectrum of C-PCF-LPG afforded not only greatly enhanced sensing resolution, but also accuracy when the phase-shift of the fringe pattern is determined through spectral processing. Comparative numerical and experimental studies indicated LP(01) to LP(03) mode coupling as the principal coupling step for both PCF-LPG and C-PCF-LPG with emergence of multi-mode coupling at shorter grating periods or longer resonance wavelengths.

  17. Composite Fiber Hazards

    DTIC Science & Technology

    1990-12-01

    During grinding on carbon fiber composites , most of the fibers fragment into a nonfibrous dust. Of those particles retaining a fibrous shape...quantity and type of airborne carbon fibers generated from the burning of carbon fiber composites in an airplane crash. In a simulated aircraft fire...It was estimated that following an aiicraft crasl in which carbon fiber composites burned, there would be a release of 5 x 10 fibers ( ɛ om diameter

  18. Fouling behavior of microstructured hollow fiber membranes in submerged and aerated filtrations.

    PubMed

    Culfaz, P Z; Wessling, M; Lammertink, R G H

    2011-02-01

    The performance of microstructured hollow fiber membranes in submerged and aerated systems was investigated using colloidal silica as a model foulant. The microstructured fibers were compared to round fibers and to twisted microstructured fibers in flux-stepping experiments. The fouling resistances in the structured fibers were found to be higher than those of round fibers. This was attributed to stagnant zones in the grooves of the structured fibers. As the bubble sizes were larger than the size of the grooves of the structured fibers, it is possible that neither the bubbles nor the secondary flow caused by the bubbles can reach the bottom parts of the grooves. Twisting the structured fibers around their axes resulted in decreased fouling resistances. Large, cap-shaped bubbles and slugs were found to be the most effective in fouling removal, while small bubbles of sizes similar to the convolutions in the structured fiber did not cause an improvement in these fibers. Modules in a vertical orientation performed better than horizontal modules when coarse bubbling was used. For small bubbles, the difference between vertical and horizontal modules was not significant. When the structured and twisted fibers were compared to round fibers with respect to the permeate flowrate produced per fiber length instead of the actual flux through the convoluted membrane area, they showed lower fouling resistance than round fibers. This is because the enhancement in surface area is more than the increase in resistance caused by stagnant zones in the grooves of the structured fibers. From a practical point of view, although the microstructure does not promote further turbulence in submerged and aerated systems, it can still be possible to enhance productivity per module with the microstructured fibers due to their high surface area-to-volume ratio. © 2010 Elsevier Ltd. All rights reserved.

  19. Experimental fossilization of mat-forming cyanobacteria in coarse-grained siliciclastic sediments.

    PubMed

    Newman, S A; Klepac-Ceraj, V; Mariotti, G; Pruss, S B; Watson, N; Bosak, T

    2017-02-11

    Microbial fossils and textures are commonly preserved in Ediacaran and early Cambrian coarse-grained siliciclastic sediments that were deposited in tidal and intertidal marine settings. In contrast, the fossilization of micro-organisms in similar marine environments of post-Cambrian age is less frequently reported. Thus, temporal discrepancies in microbial preservation may have resulted from the opening and closing of a unique taphonomic window during the terminal Proterozoic and early Phanerozoic, respectively. Here, we expand upon previous work to identify environmental factors which may have facilitated the preservation of cyanobacteria growing on siliciclastic sand, by experimentally determining the ability of microbial mats to trap small, suspended mineral grains, and precipitate minerals from ions in solution. We show that (i) fine grains coat the sheaths of filamentous cyanobacteria (e.g., Nodosilinea sp.) residing within the mat, after less than 1 week of cell growth under aerobic conditions, (ii) clay minerals do not coat sterile cellulose fibers and rarely coat unsheathed cyanobacterial cells (e.g., Nostoc sp.), (iii) stronger disturbances (where culture jars were agitated at 170 rpm; 3 mm orbital diameter) produce the smoothest and most extensive mineral veneers around cells, compared with those agitated at slower rotational speeds (150 and 0 rpm), and (iv) mineral veneers coating cyanobacterial cells are ~1 μm in width. These new findings suggest that sheathed filamentous cyanobacteria may be preferentially preserved under conditions of high fluid energy. We integrate these results into a mechanistic model that explains the preservation of microbial fossils and textures in Ediacaran sandstones and siltstones, and in fine-grained siliciclastic deposits that contain exceptionally preserved microbial mats.

  20. Coarse mode aerosol measurement using a Low Turbulence Inlet

    NASA Astrophysics Data System (ADS)

    Brooke, J.; Bart, M.; Trembath, J.; McQuaid, J. B.; Brooks, B. J.; Osborne, S.

    2012-04-01

    The Sahara desert is a major natural source of global mineral dust emissions (Forster et al., 2007) through the mobilisation and lifting of dust particles into the atmosphere from dust storms. A significant fraction of this dust is in the aerosol coarse mode (Weinzierl et al., 2009). It is highlighted of the difficulty in making accurate and reliable measurements from an aircraft platform, particularly that of coarse mode aerosol (Wendisch et al., 2004). To achieve the measurement of a representative aerosol sample an aerosol inlet, on an aircraft, is required for the delivery of the sample to the instruments making the measurements. Inlet design can modify aerosol size distribution through either underestimating due to aerosol losses or overestimation due to enhancements. The Low Turbulence Inlet (LTI) was designed to improve inlet efficiency. This is achieved by reducing turbulence flow within the tip of the inlet, reducing impaction of particles to the walls of the inlet (Wilson et al., 2004). The LTI further maintains isokinetic sampling flow (free stream velocity, U0 and sampling velocity, U are equal to 1). Dust aerosol over the Sahara desert provides an excellent environment to test and quantify the capabilities of the LTI on the FAAM BAe 146, whilst enabling in-situ dust measurement. The LTI was operated during the Fennec field campaign in June 2011 with 11 flights during the campaign over Mauritania and Mali. We are using the LTI to provide critical information on the sampling characteristics of the inlet used by nearly all aerosol instruments inside the aircraft (AMS, Nephelometer, PSAP, and CCN). Inlet experiments were performed with identical Optical Particle Counters (OPC) connected to the rosemount and LTI with size distribution for each inlet measured and Rosemount enhancements determined. Rosemount inlet enhancements were determined to be 2 to 4 times for particles up to 2.5 µm. A key parameter in aerosol measurement is size distribution, in which

  1. Thermoluminescence characteristics of Ge-doped optical fibers with different dimensions for radiation dosimetry.

    PubMed

    Begum, Mahfuza; Rahman, A K M Mizanur; Abdul-Rashid, H A; Yusoff, Z; Begum, Mahbuba; Mat-Sharif, K A; Amin, Y M; Bradley, D A

    2015-06-01

    Important thermoluminescence (TL) properties of five (5) different core sizes Ge-doped optical fibers have been studied to develop new TL material with better response. These are drawn from same preform applying different speed and tension during drawing phase to produce Ge-doped optical fibers with five (5) different core sizes. The results of the investigations are also compared with most commonly used standard TLD-100 chips (LiF:Mg,Ti) and commercial multimode Ge-doped optical fiber (Yangtze Optical Fiber, China). Scanning Electron Microscope (SEM) and EDX analysis of the fibers are also performed to map Ge distribution across the deposited region. Standard Gamma radiation source in Secondary Standard Dosimetry Lab (SSDL) was used for irradiation covering dose range from 1Gy to 10Gy. The essential dosimetric parameters that have been studied are TL linearity, reproducibility and fading. Prior to irradiation all samples ∼0.5cm length are annealed at temperature of 400°C for 1h period to standardize their sensitivities and background. Standard TLD-100 chips are also annealed for 1h at 400°C and subsequently 2h at 100°C to yield the highest sensitivity. TL responses of these fibers show linearity over a wide gamma radiation dose that is an important property for radiation dosimetry. Among all fibers used in this study, 100μm core diameter fiber provides highest response that is 2.6 times than that of smallest core (20μm core) optical fiber. These fiber-samples demonstrate better response than commercial multi-mode optical fiber and also provide low degree of fading about 20% over a period of fifteen days for gamma radiation. Effective atomic number (Zeff) is found in the range (13.25-13.69) which is higher than soft tissue (7.5) however within the range of human-bone (11.6-13.8). All the fibers can also be re-used several times as a detector after annealing. TL properties of the Ge-doped optical fibers indicate promising applications in ionizing radiation

  2. A coarse to fine minutiae-based latent palmprint matching.

    PubMed

    Liu, Eryun; Jain, Anil K; Tian, Jie

    2013-10-01

    With the availability of live-scan palmprint technology, high resolution palmprint recognition has started to receive significant attention in forensics and law enforcement. In forensic applications, latent palmprints provide critical evidence as it is estimated that about 30 percent of the latents recovered at crime scenes are those of palms. Most of the available high-resolution palmprint matching algorithms essentially follow the minutiae-based fingerprint matching strategy. Considering the large number of minutiae (about 1,000 minutiae in a full palmprint compared to about 100 minutiae in a rolled fingerprint) and large area of foreground region in full palmprints, novel strategies need to be developed for efficient and robust latent palmprint matching. In this paper, a coarse to fine matching strategy based on minutiae clustering and minutiae match propagation is designed specifically for palmprint matching. To deal with the large number of minutiae, a local feature-based minutiae clustering algorithm is designed to cluster minutiae into several groups such that minutiae belonging to the same group have similar local characteristics. The coarse matching is then performed within each cluster to establish initial minutiae correspondences between two palmprints. Starting with each initial correspondence, a minutiae match propagation algorithm searches for mated minutiae in the full palmprint. The proposed palmprint matching algorithm has been evaluated on a latent-to-full palmprint database consisting of 446 latents and 12,489 background full prints. The matching results show a rank-1 identification accuracy of 79.4 percent, which is significantly higher than the 60.8 percent identification accuracy of a state-of-the-art latent palmprint matching algorithm on the same latent database. The average computation time of our algorithm for a single latent-to-full match is about 141 ms for genuine match and 50 ms for impostor match, on a Windows XP desktop system with 2

  3. Coarse graining the distribution function of cold dark matter - II

    NASA Astrophysics Data System (ADS)

    Henriksen, R. N.

    2004-12-01

    We study analytically the coarse- and fine-grained distribution function (DF) established by the self-similar infall of collisionless matter. We find this function explicitly for isotropic and spherically symmetric systems in terms of cosmological initial conditions. The coarse-grained function is structureless and steady but the familiar phase-space sheet substructure is recovered in the fine-grained limit. By breaking the self-similarity of the halo infall we are able to argue for a central density flattening. In addition there will be an edge steepening. The best-fitting analytic density function is likely to be provided by a high-order polytrope fit smoothly to an outer power law of index -3 for isolated systems. There may be a transition to a -4 power law in the outer regions of tidally truncated systems. As we find that the central flattening is progressive in time, dynamically young systems such as galaxy clusters may well possess a Navarro, Frenk and White type density profile, while primordial dwarf galaxies, for example, are expected to have cores. This progressive flattening is expected to end either in the non-singular isothermal sphere, or in the non-singular metastable polytropic cores; as the DFs associated with each of these arise naturally in the bulk halo during the infall. We suggest, based on previous studies of the evolution of de-stabilized polytropes, that a collisionless system may pass through a family of polytropes of increasing order, finally approaching the limit of the non-singular isothermal sphere, if the `violent' collective relaxation is frequently re-excited by `merger' events. Thus central dominant (cD) galaxies, and indeed all bright galaxies that have grown in this fashion, should be in polytropic states. Our results suggest that no physics beyond that of wave-particle scattering is necessary to explain the nature of dark matter density profiles. However, this may be assisted by the scattering of particles from the centre of the

  4. Multistage point relascope and randomized branch sampling for downed coarse woody debris estimation

    Treesearch

    Jeffrey H. Gove; Mark J. Ducey; Harry T. Valentine

    2002-01-01

    New sampling methods have recently been introduced that allow estimation of downed coarse woody debris using an angle gauge, or relascope. The theory behind these methods is based on sampling straight pieces of downed coarse woody debris. When pieces deviate from this ideal situation, auxillary methods must be employed. We describe a two-stage procedure where the...

  5. The decomposition of fine and coarse roots: their global patterns and controlling factors

    PubMed Central

    Zhang, Xinyue; Wang, Wei

    2015-01-01

    Fine root decomposition represents a large carbon (C) cost to plants, and serves as a potential soil C source, as well as a substantial proportion of net primary productivity. Coarse roots differ markedly from fine roots in morphology, nutrient concentrations, functions, and decomposition mechanisms. Still poorly understood is whether a consistent global pattern exists between the decomposition of fine (<2 mm root diameter) and coarse (≥2 mm) roots. A comprehensive terrestrial root decomposition dataset, including 530 observations from 71 sampling sites, was thus used to compare global patterns of decomposition of fine and coarse roots. Fine roots decomposed significantly faster than coarse roots in middle latitude areas, but their decomposition in low latitude regions was not significantly different from that of coarse roots. Coarse root decomposition showed more dependence on climate, especially mean annual temperature (MAT), than did fine roots. Initial litter lignin content was the most important predictor of fine root decomposition, while lignin to nitrogen ratios, MAT, and mean annual precipitation were the most important predictors of coarse root decomposition. Our study emphasizes the necessity of separating fine roots and coarse roots when predicting the response of belowground C release to future climate changes. PMID:25942391

  6. Chemical Characterization of Coarse Particulate Matter in the Desert Southwest - Pinal County Arizona, USA

    EPA Science Inventory

    The Desert Southwest Coarse Particulate Matter Study was undertaken of ambient concentrations and the composition of fine and coarse particles in rural, arid environments. Sampling was conducted in Pinal County, Arizona between February 2009 and February 2010. The goals of this ...

  7. DEVELOPMENT AND EVALUATION OF A CONTINUOUS COARSE (PM10-PM2.5) PARTICLE MONITOR

    EPA Science Inventory

    In this paper, we describe the development and laboratory and field evaluation of a continuous coarse (2.5-10 um) particle mass (PM) monitor that can provide reliable measurements of the coarse mass (CM) concentrations in time intervals as short as 5-10 min. The operating princ...

  8. Information-theoretic tools for parametrized coarse-graining of non-equilibrium extended systems

    NASA Astrophysics Data System (ADS)

    Katsoulakis, Markos A.; Plecháč, Petr

    2013-08-01

    In this paper, we focus on the development of new methods suitable for efficient and reliable coarse-graining of non-equilibrium molecular systems. In this context, we propose error estimation and controlled-fidelity model reduction methods based on Path-Space Information Theory, combined with statistical parametric estimation of rates for non-equilibrium stationary processes. The approach we propose extends the applicability of existing information-based methods for deriving parametrized coarse-grained models to Non-Equilibrium systems with Stationary States. In the context of coarse-graining it allows for constructing optimal parametrized Markovian coarse-grained dynamics within a parametric family, by minimizing information loss (due to coarse-graining) on the path space. Furthermore, we propose an asymptotically equivalent method—related to maximum likelihood estimators for stochastic processes—where the coarse-graining is obtained by optimizing the information content in path space of the coarse variables, with respect to the projected computational data from a fine-scale simulation. Finally, the associated path-space Fisher Information Matrix can provide confidence intervals for the corresponding parameter estimators. We demonstrate the proposed coarse-graining method in (a) non-equilibrium systems with diffusing interacting particles, driven by out-of-equilibrium boundary conditions, as well as (b) multi-scale diffusions and the corresponding stochastic averaging limits, comparing them to our proposed methodologies.

  9. The combustion of sound and rotten coarse woody debris: a review

    Treesearch

    Joshua C. Hyde; Alistair M.S. Smith; Roger D. Ottmar; Ernesto C. Alvarado; Penelope. Morgan

    2011-01-01

    Coarse woody debris serves many functions in forest ecosystem processes and has important implications for fire management as it affects air quality, soil heating and carbon budgets when it combusts. There is relatively little research evaluating the physical properties relating to the combustion of this coarse woody debris with even less specifically addressing...

  10. Source identification of coarse particles in the Desert Southwest, USA using Positive Matrix Factorization

    EPA Science Inventory

    The Desert Southwest Coarse Particulate Matter Study was undertaken to further our understanding of the spatial and temporal variability and sources of fine and coarse particulate matter (PM) in rural, arid, desert environments. Sampling was conducted between February 2009 and Fe...

  11. Chemical Characterization of Coarse Particulate Matter in the Desert Southwest - Pinal County Arizona, USA

    EPA Science Inventory

    The Desert Southwest Coarse Particulate Matter Study was undertaken of ambient concentrations and the composition of fine and coarse particles in rural, arid environments. Sampling was conducted in Pinal County, Arizona between February 2009 and February 2010. The goals of this ...

  12. Characterization of coarse woody debris across a 100 year chronosequence of upland oak-hickory forest

    Treesearch

    Travis W. Idol; Phillip E. Pope; Rebecca A. Figler; Felix Ponder Jr.

    1999-01-01

    Coarse woody debris is an important component influencing forest nutrient cycling and contributes to long-term soil productivity. The common practice of classifying coarse woody debris into different decomposition classes has seldom been related to the chemistry/biochemistry of the litter, which is the long term objective of our research. The objective of this...

  13. The decomposition of fine and coarse roots: their global patterns and controlling factors.

    PubMed

    Zhang, Xinyue; Wang, Wei

    2015-05-05

    Fine root decomposition represents a large carbon (C) cost to plants, and serves as a potential soil C source, as well as a substantial proportion of net primary productivity. Coarse roots differ markedly from fine roots in morphology, nutrient concentrations, functions, and decomposition mechanisms. Still poorly understood is whether a consistent global pattern exists between the decomposition of fine (<2 mm root diameter) and coarse (≥2 mm) roots. A comprehensive terrestrial root decomposition dataset, including 530 observations from 71 sampling sites, was thus used to compare global patterns of decomposition of fine and coarse roots. Fine roots decomposed significantly faster than coarse roots in middle latitude areas, but their decomposition in low latitude regions was not significantly different from that of coarse roots. Coarse root decomposition showed more dependence on climate, especially mean annual temperature (MAT), than did fine roots. Initial litter lignin content was the most important predictor of fine root decomposition, while lignin to nitrogen ratios, MAT, and mean annual precipitation were the most important predictors of coarse root decomposition. Our study emphasizes the necessity of separating fine roots and coarse roots when predicting the response of belowground C release to future climate changes.

  14. Modeling respiration from snags and coarse woody debris before and after an invasive gypsy moth disturbance

    Treesearch

    Heidi J. Renninger; Nicholas Carlo; Kenneth L. Clark; Karina V.R. Schäfer

    2014-01-01

    Although snags and coarse woody debris are a small component of ecosystem respiration, disturbances can significantly increase the mass and respiration from these carbon (C) pools. The objectives of this study were to (1) measure respiration rates of snags and coarse woody debris throughout the year in a forest previously defoliated by gypsy moths, (2) develop models...

  15. DEVELOPMENT AND EVALUATION OF A CONTINUOUS COARSE (PM10-PM2.5) PARTICLE MONITOR

    EPA Science Inventory

    In this paper, we describe the development and laboratory and field evaluation of a continuous coarse (2.5-10 um) particle mass (PM) monitor that can provide reliable measurements of the coarse mass (CM) concentrations in time intervals as short as 5-10 min. The operating princ...

  16. Molecular Renormalization Group Coarse-Graining of Polymer Chains: Application to Double-Stranded DNA

    PubMed Central

    Savelyev, Alexey; Papoian, Garegin A.

    2009-01-01

    Coarse-graining of atomistic force fields allows us to investigate complex biological problems, occurring at long timescales and large length scales. In this work, we have developed an accurate coarse-grained model for double-stranded DNA chain, derived systematically from atomistic simulations. Our approach is based on matching correlators obtained from atomistic and coarse-grained simulations, for observables that explicitly enter the coarse-grained Hamiltonian. We show that this requirement leads to equivalency of the corresponding partition functions, resulting in a one-step renormalization. Compared to prior works exploiting similar ideas, the main novelty of this work is the introduction of a highly compact set of Hamiltonian basis functions, based on molecular interaction potentials. We demonstrate that such compactification allows us to reproduce many-body effects, generated by one-step renormalization, at low computational cost. In addition, compact Hamiltonians greatly increase the likelihood of finding unique solutions for the coarse-grained force-field parameter values. By successfully applying our molecular renormalization group coarse-graining technique to double-stranded DNA, we solved, for the first time, a long-standing problem in coarse-graining polymer systems, namely, how to accurately capture the correlations among various polymeric degrees of freedom. Excellent agreement is found among atomistic and coarse-grained distribution functions for various structural observables, including those not included in the Hamiltonian. We also suggest higher-order generalization of this method, which may allow capturing more subtle correlations in biopolymer dynamics. PMID:19450476

  17. Advanced Interrogation of Fiber-Optic Bragg Grating and Fabry-Perot Sensors with KLT Analysis

    PubMed Central

    Tosi, Daniele

    2015-01-01

    The Karhunen-Loeve Transform (KLT) is applied to accurate detection of optical fiber sensors in the spectral domain. By processing an optical spectrum, although coarsely sampled, through the KLT, and subsequently processing the obtained eigenvalues, it is possible to decode a plurality of optical sensor results. The KLT returns higher accuracy than other demodulation techniques, despite coarse sampling, and exhibits higher resilience to noise. Three case studies of KLT-based processing are presented, representing most of the current challenges in optical fiber sensing: (1) demodulation of individual sensors, such as Fiber Bragg Gratings (FBGs) and Fabry-Perot Interferometers (FPIs); (2) demodulation of dual (FBG/FPI) sensors; (3) application of reverse KLT to isolate different sensors operating on the same spectrum. A simulative outline is provided to demonstrate the KLT operation and estimate performance; a brief experimental section is also provided to validate accurate FBG and FPI decoding. PMID:26528975

  18. Advanced Interrogation of Fiber-Optic Bragg Grating and Fabry-Perot Sensors with KLT Analysis.

    PubMed

    Tosi, Daniele

    2015-10-29

    The Karhunen-Loeve Transform (KLT) is applied to accurate detection of optical fiber sensors in the spectral domain. By processing an optical spectrum, although coarsely sampled, through the KLT, and subsequently processing the obtained eigenvalues, it is possible to decode a plurality of optical sensor results. The KLT returns higher accuracy than other demodulation techniques, despite coarse sampling, and exhibits higher resilience to noise. Three case studies of KLT-based processing are presented, representing most of the current challenges in optical fiber sensing: (1) demodulation of individual sensors, such as Fiber Bragg Gratings (FBGs) and Fabry-Perot Interferometers (FPIs); (2) demodulation of dual (FBG/FPI) sensors; (3) application of reverse KLT to isolate different sensors operating on the same spectrum. A simulative outline is provided to demonstrate the KLT operation and estimate performance; a brief experimental section is also provided to validate accurate FBG and FPI decoding.

  19. Upper Atmosphere Research Satellite (UARS) attitude accuracy using coarse attitude sensors

    NASA Technical Reports Server (NTRS)

    Krack, K.; Foch, D.; Lambertson, M.; Woolsey, C.; Underwood, S.; Woodruff, C.; Garrick, J.

    1993-01-01

    The Upper Atmosphere Research Satellite (UARS) uses fixed-head star trackers (FHST's) and inertial reference units (IRU's) to determine and control its attitude. This combination of fine sensors results in attitude knowledge accuracies to better than 10 arc-seconds (1 sigma). UARS also has a variety of coarse attitude sensors on board: the three-axis magnetometer (TAM), the coarse Sun sensor (CSS), the fine Sun sensor (FSS), and the Earth sensor assembly (ESA). By comparing attitude solutions using coarse sensors with FHST-determined attitude solutions, estimates can be made of the accuracy of the coarse sensors. This paper presents the results of an analysis that compares attitude solutions using various combinations of UARS coarse attitude sensor data with FHST attitude solutions.

  20. Ceramic ware waste as coarse aggregate for structural concrete production.

    PubMed

    García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia M; Guerra-Romero, M Ignacio

    2015-01-01

    The manufacture of any kind of product inevitably entails the production of waste. The quantity of waste generated by the ceramic industry, a very important sector in Spain, is between 5% and 8% of the final output and it is therefore necessary to find an effective waste recovery method. The aim of the study reported in the present article was to seek a sustainable means of managing waste from the ceramic industry through the incorporation of this type of waste in the total replacement of conventional aggregate (gravel) used in structural concrete. Having verified that the recycled ceramic aggregates met all the technical requirements imposed by current Spanish legislation, established in the Code on Structural Concrete (EHE-08), then it is prepared a control concrete mix and the recycled concrete mix using 100% recycled ceramic aggregate instead of coarse natural aggregate. The concretes obtained were subjected to the appropriate tests in order to conduct a comparison of their mechanical properties. The results show that the concretes made using ceramic sanitary ware aggregate possessed the same mechanical properties as those made with conventional aggregate. It is therefore possible to conclude that the reuse of recycled ceramic aggregate to produce recycled concrete is a feasible alternative for the sustainable management of this waste.

  1. Coarse graining of star-polymer - colloid nanocomposites

    NASA Astrophysics Data System (ADS)

    Marzi, Daniela; Likos, Christos N.; Capone, Barbara

    2012-07-01

    We consider mixtures of self-avoiding multiarm star polymers with hard colloids that are smaller than the star polymer size. By employing computer simulations, and by extending previous theoretical approaches, developed for the opposite limit of small star polymers [A. Jusufi et al., J. Phys.: Condens. Matter 13, 6177 (2001), 10.1088/0953-8984/13/28/303], we coarse-grain the mixture by deriving an effective cross-interaction between the unlike species. The excellent agreement between theory and simulation for all size ratios examined demonstrates that the theoretical approaches developed for the colloidal limit can be successfully modified to maintain their validity also for the present case of the protein limit, in contrast to the situation for mixtures of colloids and linear polymers. We further analyze, on the basis of the derived interactions, the non-additivity parameter of the mixture as a function of size ratio and star functionality and delineate the regions in which we expect mixing as opposed to demixing behavior. Our results are relevant for the study of star-colloid nanocomposites and pave the way for further investigations of the structure and thermodynamics of the same.

  2. Coarse-grained description of cosmic structure from Szekeres models

    SciTech Connect

    Sussman, Roberto A.; Gaspar, I. Delgado; Hidalgo, Juan Carlos E-mail: ismael.delgadog@uaem.edu.mx

    2016-03-01

    We show that the full dynamical freedom of the well known Szekeres models allows for the description of elaborated 3-dimensional networks of cold dark matter structures (over-densities and/or density voids) undergoing ''pancake'' collapse. By reducing Einstein's field equations to a set of evolution equations, which themselves reduce in the linear limit to evolution equations for linear perturbations, we determine the dynamics of such structures, with the spatial comoving location of each structure uniquely specified by standard early Universe initial conditions. By means of a representative example we examine in detail the density contrast, the Hubble flow and peculiar velocities of structures that evolved, from linear initial data at the last scattering surface, to fully non-linear 10–20 Mpc scale configurations today. To motivate further research, we provide a qualitative discussion on the connection of Szekeres models with linear perturbations and the pancake collapse of the Zeldovich approximation. This type of structure modelling provides a coarse grained—but fully relativistic non-linear and non-perturbative —description of evolving large scale cosmic structures before their virialisation, and as such it has an enormous potential for applications in cosmological research.

  3. Near-road enhancement and solubility of fine and coarse ...

    EPA Pesticide Factsheets

    Communities near major roadways are disproportionately affected by traffic-related air pollution which can contribute to adverse health outcomes. The specific role of particulate matter (PM) from traffic sources is not fully understood due to complex emissions processes and physical/chemical properties of PM in the near-road environment. To investigate the spatial profile and water solubility of elemental PM species near a major roadway, filter-based measurements of fine (PM2.5) and coarse (PM10-2.5) PM were simultaneously collected at multiple distances (10 m, 100 m, and 300 m) from Interstate I-96 in Detroit, Michigan during September–November 2010. Filters were extracted in water, followed by a hot acid extraction, and analyzed by magnetic sector field high resolution inductively coupled plasma mass spectrometry (HR-ICPMS) to quantify water-soluble and acid-soluble trace elements for each PM size fraction. PM2.5 and PM10-2.5 species measured in the near-road samples included elements associated with traffic activity, local industrial sources, and regional pollution. Metals indicative of brake wear (Ba, Cu) were dramatically enriched near the roadway during downwind conditions (factor of 5 concentration increase), with the largest increase within 100 m of the roadway. Moderate near-roadway increases were observed for crustal elements and other traffic-related PM (Fe, Ca), and the lowest increases observed for regional PM species (S). Water solubility varied

  4. Coarse graining approach to First principles modeling of structural materials

    SciTech Connect

    Odbadrakh, Khorgolkhuu; Nicholson, Don M; Rusanu, Aurelian; Samolyuk, German D; Wang, Yang; Stoller, Roger E; Zhang, X.-G.; Stocks, George Malcolm

    2013-01-01

    Classical Molecular Dynamic (MD) simulations characterizing extended defects typically require millions of atoms. First principles calculations employed to understand these defect systems at an electronic level cannot, and should not deal with such large numbers of atoms. We present an e cient coarse graining (CG) approach to calculate local electronic properties of large MD-generated structures from the rst principles. We used the Locally Self-consistent Multiple Scattering (LSMS) method for two types of iron defect structures 1) screw-dislocation dipoles and 2) radiation cascades. The multiple scattering equations are solved at fewer sites using the CG. The atomic positions were determined by MD with an embedded atom force eld. The local moments in the neighborhood of the defect cores are calculated with rst-principles based on full local structure information, while atoms in the rest of the system are modeled by representative atoms with approximated properties. This CG approach reduces computational costs signi cantly and makes large-scale structures amenable to rst principles study. Work is sponsored by the USDoE, O ce of Basic Energy Sciences, Center for Defect Physics, an Energy Frontier Research Center. This research used resources of the Oak Ridge Leadership Computing Facility at the ORNL, which is supported by the O ce of Science of the USDoE under Contract No. DE-AC05-00OR22725.

  5. Coarse-grained molecular simulations of allosteric cooperativity

    NASA Astrophysics Data System (ADS)

    Nandigrami, Prithviraj; Portman, John J.

    2016-03-01

    Interactions between a protein and a ligand are often accompanied by a redistribution of the population of thermally accessible conformations. This dynamic response of the protein's functional energy landscape enables a protein to modulate binding affinities and control binding sensitivity to ligand concentration. In this paper, we investigate the structural origins of binding affinity and allosteric cooperativity of binding two Ca2+ ions to each domain of Calmodulin (CaM) through simulations of a simple coarse-grained model. In this model, the protein's conformational transitions between open and closed conformational ensembles are simulated explicitly and ligand binding and unbinding are treated implicitly within the grand canonical ensemble. Ligand binding is cooperative because the binding sites are coupled through a shift in the dominant conformational ensemble upon binding. The classic Monod-Wyman-Changeux model of allostery with appropriate binding free energies to the open and closed ensembles accurately describes the simulated binding thermodynamics. The simulations predict that the two domains of CaM have distinct binding affinity and cooperativity. In particular, the C-terminal domain binds Ca2+ with higher affinity and greater cooperativity than the N-terminal domain. From a structural point of view, the affinity of an individual binding loop depends sensitively on the loop's structural compatibility with the ligand in the bound ensemble, as well as the conformational flexibility of the binding site in the unbound ensemble.

  6. Coarse-grained modeling of polyethylene melts: Effect on dynamics

    DOE PAGES

    Peters, Brandon L.; Salerno, K. Michael; Agrawal, Anupriya; ...

    2017-05-23

    The distinctive viscoelastic behavior of polymers results from a coupled interplay of motion on multiple length and time scales. Capturing the broad time and length scales of polymer motion remains a challenge. Using polyethylene (PE) as a model macromolecule, we construct coarse-grained (CG) models of PE with three to six methyl groups per CG bead and probe two critical aspects of the technique: pressure corrections required after iterative Boltzmann inversion (IBI) to generate CG potentials that match the pressure of reference fully atomistic melt simulations and the transferability of CG potentials across temperatures. While IBI produces nonbonded pair potentials thatmore » give excellent agreement between the atomistic and CG pair correlation functions, the resulting pressure for the CG models is large compared with the pressure of the atomistic system. We find that correcting the potential to match the reference pressure leads to nonbonded interactions with much deeper minima and slightly smaller effective bead diameter. However, simulations with potentials generated by IBI and pressure-corrected IBI result in similar mean-square displacements (MSDs) and stress autocorrelation functions G(t) for PE melts. While the time rescaling factor required to match CG and atomistic models is the same for pressure- and non-pressure-corrected CG models, it strongly depends on temperature. Furthermore, transferability was investigated by comparing the MSDs and stress autocorrelation functions for potentials developed at different temperatures.« less

  7. Entrainment of coarse grains using a discrete particle model

    SciTech Connect

    Valyrakis, Manousos; Arnold, Roger B. Jr.

    2014-10-06

    Conventional bedload transport models and incipient motion theories relying on a time-averaged boundary shear stress are incapable of accounting for the effects of fluctuating near-bed velocity in turbulent flow and are therefore prone to significant errors. Impulse, the product of an instantaneous force magnitude and its duration, has been recently proposed as an appropriate criterion for quantifying the effects of flow turbulence in removing coarse grains from the bed surface. Here, a discrete particle model (DPM) is used to examine the effects of impulse, representing a single idealized turbulent event, on particle entrainment. The results are classified according to the degree of grain movement into the following categories: motion prior to entrainment, initial dislodgement, and energetic displacement. The results indicate that in all three cases the degree of particle motion depends on both the force magnitude and the duration of its application and suggest that the effects of turbulence must be adequately accounted for in order to develop a more accurate method of determining incipient motion. DPM is capable of simulating the dynamics of grain entrainment and is an appropriate tool for further study of the fundamental mechanisms of sediment transport.

  8. Coarse particulate matter emissions from cattle feedlots in Australia.

    PubMed

    McGinn, S M; Flesch, T K; Chen, D; Crenna, B; Denmead, O T; Naylor, T; Rowell, D

    2010-01-01

    Open cattle feedlots are a source of air pollutants that include particular matter (PM). Over 24 h, exposure to ambient concentrations of 50 microg m(-3) of the coarse-sized fraction PM (aerodynamic diameter <10 microm [PM(10)]) is recognized as a health concern for humans. The objective of our study was to document PM(10) concentration and emissions at two cattle feedlots in Australia over several days in summer. Two automated samplers were used to monitor the background and in-feedlot PM(10) concentrations. At the in-feedlot location, the PM(10) emission was calculated using a dispersion model. Our measurements revealed that the 24-h PM(10) concentrations on some of the days approached or exceeded the health criteria threshold of 50 microg m(-3) used in Australia. A key factor responsible for the generation of PM(10) was the increased activity of cattle in the evening that coincided with peak concentrations of PM(10) (maximum, 792 microg m(-3)) between 1930 and 2000 h. Rain coincided with a severe decline in PM(10) concentration and emission. A dispersion model used in our study estimated the emission of PM(10) between 31 and 60 g animal(-1) d(-1). These data contribute to needed information on PM(10) associated with livestock to develop results-based environmental policy.

  9. Coarse-Grained Molecular Models of Water: A Review

    PubMed Central

    Hadley, Kevin R.; McCabe, Clare

    2012-01-01

    Coarse-grained (CG) models have proven to be very effective tools in the study of phenomena or systems that involve large time- and length-scales. By decreasing the degrees of freedom in the system and using softer interactions than seen in atomistic models, larger timesteps can be used and much longer simulation times can be studied. CG simulations are widely used to study systems of biological importance that are beyond the reach of atomistic simulation, necessitating a computationally efficient and accurate CG model for water. In this review, we discuss the methods used for developing CG water models and the relative advantages and disadvantages of the resulting models. In general, CG water models differ with regards to how many waters each CG group or bead represents, whether analytical or tabular potentials have been used to describe the interactions, and how the model incorporates electrostatic interactions. Finally, how the models are parameterized depends on their application, so, while some are fitted to experimental properties such as surface tension and density, others are fitted to radial distribution functions extracted from atomistic simulations. PMID:22904601

  10. Perspective: Coarse-grained models for biomolecular systems

    NASA Astrophysics Data System (ADS)

    Noid, W. G.

    2013-09-01

    By focusing on essential features, while averaging over less important details, coarse-grained (CG) models provide significant computational and conceptual advantages with respect to more detailed models. Consequently, despite dramatic advances in computational methodologies and resources, CG models enjoy surging popularity and are becoming increasingly equal partners to atomically detailed models. This perspective surveys the rapidly developing landscape of CG models for biomolecular systems. In particular, this review seeks to provide a balanced, coherent, and unified presentation of several distinct approaches for developing CG models, including top-down, network-based, native-centric, knowledge-based, and bottom-up modeling strategies. The review summarizes their basic philosophies, theoretical foundations, typical applications, and recent developments. Additionally, the review identifies fundamental inter-relationships among the diverse approaches and discusses outstanding challenges in the field. When carefully applied and assessed, current CG models provide highly efficient means for investigating the biological consequences of basic physicochemical principles. Moreover, rigorous bottom-up approaches hold great promise for further improving the accuracy and scope of CG models for biomolecular systems.

  11. Coarse cluster enhancing collaborative recommendation for social network systems

    NASA Astrophysics Data System (ADS)

    Zhao, Yao-Dong; Cai, Shi-Min; Tang, Ming; Shang, Min-Sheng

    2017-10-01

    Traditional collaborative filtering based recommender systems for social network systems bring very high demands on time complexity due to computing similarities of all pairs of users via resource usages and annotation actions, which thus strongly suppresses recommending speed. In this paper, to overcome this drawback, we propose a novel approach, namely coarse cluster that partitions similar users and associated items at a high speed to enhance user-based collaborative filtering, and then develop a fast collaborative user model for the social tagging systems. The experimental results based on Delicious dataset show that the proposed model is able to dramatically reduce the processing time cost greater than 90 % and relatively improve the accuracy in comparison with the ordinary user-based collaborative filtering, and is robust for the initial parameter. Most importantly, the proposed model can be conveniently extended by introducing more users' information (e.g., profiles) and practically applied for the large-scale social network systems to enhance the recommending speed without accuracy loss.

  12. Fine and coarse components in surface sediments from Bikini Lagoon

    SciTech Connect

    Noshkin, V. E., LLNL

    1997-01-01

    In 1979, 21 years after the moratorium on nuclear testing in the Marshall Islands, surface sediment samples (to depths of 2 and 4 cm) were collected from 87 locations in the lagoon of Bikini Atoll, one of the two sites in the Marshall Islands used by the United States to test nuclear devices from 1946 through 1958. The main purpose for the collections was to map the distribution of long-lived man-made radionuclides associated with the bottom material. In addition the samples were processed to estimate the fraction of fine and coarse components to show, by comparison, what modifications occurred in the composition since the sediments were first described in samples collected before testing in 1946. Nuclear testing produced more finely divided material that is now found in the surface sediment layer over large areas of the lagoon and especially in regions of the lagoon and reef adjacent to test sites. The 5 cratering events alone at Bikini Atoll redistributed sufficient material to account for the higher inventory of fine material found over the surface 4 cm of the sediment of the lagoon. Although the fraction of fine material in the bottom sediments was altered by the nuclear events, the combined processes of formation, transport and deposition were not sufficiently dynamic to greatly change the general geographical features of the major sedimentary components over most of the lagoon floor.

  13. Safety Ellipse Motion with Coarse Sun Angle Optimization

    NASA Technical Reports Server (NTRS)

    Naasz, Bo

    2005-01-01

    The Hubble Space Telescope Robotic Servicing and De-orbit Mission (HRSDM) was t o be performed by the unmanned Hubble Robotic Vehicle (HRV) consisting of a Deorbit Module (DM), responsible for the ultimate disposal of Hubble Space Telescope (HST) at the end of science operations, and an Ejection Module (EM), responsible for robotically servicing the HST to extend its useful operational lifetime. HRSDM consisted of eight distinct phases, including: launch, pursuit, proximity operations, capture, servicing, EM jettison and disposal, science operations, and deorbit. The scope of this paper is limited to the Proximity Operations phase of HRSDM. It introduces a relative motion strategy useful for Autonomous Rendezvous and Docking (AR&D) or Formation Flying missions where safe circumnavigation trajectories, or close proximity operations (tens or hundreds of meters) are required for extended periods of time. Parameters and algorithms used to model the relative motion of HRV with respect to HST during the Proximity Operations phase of the HRSDM are described. Specifically, the Safety Ellipse (SE) concept, convenient parameters for describing SE motion, and a concept for initializing SE motion around a target vehicle to coarsely optimize sun and relative navigation sensor angles are presented. The effects of solar incidence angle variations on sun angle optimization, and the effects of orbital perturbations and navigation uncertainty on long term SE motion are discussed.

  14. Behaviour of Recycled Coarse Aggregate Concrete: Age and Successive Recycling

    NASA Astrophysics Data System (ADS)

    Sahoo, Kirtikanta; Pathappilly, Robin Davis; Sarkar, Pradip

    2016-06-01

    Recycled Coarse Aggregate (RCA) concrete construction technique can be called as `green concrete', as it minimizes the environmental hazard of the concrete waste disposal. Indian standard recommends target mean compressive strength of the conventional concrete in terms of water cement ratio ( w/ c). The present work is an attempt to study the behaviour of RCA concrete from two samples of parent concrete having different age group with regard to the relationship of compressive strength with water cement ratios. Number of recycling may influence the mechanical properties of RCA concrete. The influence of age and successive recycling on the properties such as capillary water absorption, drying shrinkage strain, air content, flexural strength and tensile splitting strength of the RCA concrete are examined. The relationship between compressive strength at different w/ c ratios obtained experimentally is investigated for the two parameters such as age of parent concrete and successive recycling. The recycled concrete using older recycled aggregate shows poor quality. While the compressive strength reduces with successive recycling gradually, the capillary water absorption increases abruptly, which leads to the conclusion that further recycling may not be advisable.

  15. Coarse-grained potentials of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhao, Junhua; Jiang, Jin-Wu; Wang, Lifeng; Guo, Wanlin; Rabczuk, Timon

    2014-11-01

    We develop the coarse-grained (CG) potentials of single-walled carbon nanotubes (SWCNTs) in CNT bundles and buckypaper for the study of the static and dynamic behaviors. The explicit expressions of the CG stretching, bending and torsion potentials for the nanotubes are obtained by the stick-spiral and the beam models, respectively. The non-bonded CG potentials between two different CG beads are derived from analytical results based on the cohesive energy between two parallel and crossing SWCNTs from the van der Waals interactions. We show that the CG model is applicable to large deformations of complex CNT systems by combining the bonded potentials with non-bonded potentials. Checking against full atom molecular dynamics calculations and our analytical results shows that the present CG potentials have high accuracy. The established CG potentials are used to study the mechanical properties of the CNT bundles and buckypaper efficiently at minor computational cost, which shows great potential for the design of micro- and nanomechanical devices and systems.

  16. Coarse-Grained Model for Water Involving a Virtual Site.

    PubMed

    Deng, Mingsen; Shen, Hujun

    2016-02-04

    In this work, we propose a new coarse-grained (CG) model for water by combining the features of two popular CG water models (BMW and MARTINI models) as well as by adopting a topology similar to that of the TIP4P water model. In this CG model, a CG unit, representing four real water molecules, consists of a virtual site, two positively charged particles, and a van der Waals (vdW) interaction center. Distance constraint is applied to the bonds formed between the vdW interaction center and the positively charged particles. The virtual site, which carries a negative charge, is determined by the locations of the two positively charged particles and the vdW interaction center. For the new CG model of water, we coined the name "CAVS" (charge is attached to a virtual site) due to the involvment of the virtual site. After being tested in molecular dynamic (MD) simulations of bulk water at various time steps, under different temperatures and in different salt (NaCl) concentrations, the CAVS model offers encouraging predictions for some bulk properties of water (such as density, dielectric constant, etc.) when compared to experimental ones.

  17. Non-conformal coarse-grained potentials for water.

    PubMed

    Rodríguez-López, Tonalli; Khalak, Yuriy; Karttunen, Mikko

    2017-10-07

    Water is a notoriously difficult substance to model both accurately and efficiently. Here, we focus on descriptions with a single coarse-grained particle per molecule using the so-called approximate non-conformal and generalized Stockmayer potentials as the starting points. They are fitted using the radial distribution function and the liquid-gas density profile of the atomistic extended simple point charge (SPC/E) model by downhill simplex optimization. We compare the results with monatomic water (mW), ELBA, and direct iterative Boltzmann inversion of SPC/E. The results show that symmetrical potentials result in non-transferable models, that is, they need to be reparametrized for new state points. This indicates that transferability may require more complex models. Furthermore, the results also show that the addition of a point dipole is not sufficient to make the potentials accurate and transferable to different temperatures (300 K-500 K) and pressures without an appropriate choice of properties as targets during model optimization.

  18. A kinetic chain growth algorithm in coarse-grained simulations.

    PubMed

    Liu, Hong; Zhu, You-Liang; Lu, Zhong-Yuan; Müller-Plathe, Florian

    2016-11-15

    We propose a kinetic chain growth algorithm for coarse-grained (CG) simulations in this work. By defining the reaction probability, it delivers a description of consecutive polymerization process. This algorithm is validated by modeling the process of individual styrene monomers polymerizing into polystyrene chains, which is proved to correctly reproduce the properties of polymers in experiments. By bridging the relationship between the generic chain growth process in CG simulations and the chemical details, the impediment to reaction can be reflected. Regarding to the kinetics, it models a polymerization process with an Arrhenius-type reaction rate coefficient. Moreover, this algorithm can model both the gradual and jump processes of the bond formation, thus it readily encompasses several kinds of previous CG models of chain growth. With conducting smooth simulations, this algorithm can be potentially applied to describe the variable macroscopic features of polymers with the process of polymerization. The algorithm details and techniques are introduced in this article. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  19. Fuzzy logic and coarse coding using programmable logic devices

    NASA Astrophysics Data System (ADS)

    Brooks, Geoffrey

    2009-05-01

    Naturally-occurring sensory signal processing algorithms, such as those that inspired fuzzy-logic control, can be integrated into non-naturally-occurring high-performance technology, such as programmable logic devices, to realize novel bio-inspired designs. Research is underway concerning an investigation into using field programmable logic devices (FPLD's) to implement fuzzy logic sensory processing. A discussion is provided concerning the commonality between bio-inspired fuzzy logic algorithms and coarse coding that is prevalent in naturally-occurring sensory systems. Undergraduate design projects using fuzzy logic for an obstacle-avoidance robot has been accomplished at our institution and other places; numerous other successful fuzzy logic applications can be found as well. The long-term goal is to leverage such biomimetic algorithms for future applications. This paper outlines a design approach for implementing fuzzy-logic algorithms into reconfigurable computing devices. This paper is presented in an effort to connect with others who may be interested in collaboration as well as to establish a starting point for future research.

  20. Coarse Grained Model for Biological Simulations: Recent Refinements and Validation

    PubMed Central

    Vicatos, Spyridon; Rychkova, Anna; Mukherjee, Shayantani; Warshel, Arieh

    2014-01-01

    Exploring the free energy landscape of proteins and modeling the corresponding functional aspects presents a major challenge for computer simulation approaches. This challenge is due to the complexity of the landscape and the enormous computer time needed for converging simulations. The use of various simplified coarse grained (CG) models offers an effective way of sampling the landscape, but most current models are not expected to give a reliable description of protein stability and functional aspects. The main problem is associated with insufficient focus on the electrostatic features of the model. In this respect our recent CG model offers significant advantage as it has been refined while focusing on its electrostatic free energy. Here we review the current state of our model, describing recent refinement, extensions and validation studies while focusing on demonstrating key applications. These include studies of protein stability, extending the model to include membranes and electrolytes and electrodes as well as studies of voltage activated proteins, protein insertion trough the translocon, the action of molecular motors and even the coupling of the stalled ribosome and the translocon. Our example illustrates the general potential of our approach in overcoming major challenges in studies of structure function correlation in proteins and large macromolecular complexes. PMID:25050439