Science.gov

Sample records for carrads cross layer

  1. Cross-layer Optimization for Next Generation Wi-Fi

    NASA Astrophysics Data System (ADS)

    Redieteab, Getachew

    2013-01-01

    From the initial 1997 specification to the undergoing IEEE 802.11ac standardization, a leap in throughput has been observed with every new generation. The expectations for next generations on issues like throughput, range, reliability, and power consumption are even higher. This is quite a challenge considering all the work already done. Cross-layer optimization of physical (PHY) and medium access control (MAC) layers can be an interesting exploration path for further enhancement. During this thesis we have studied cross-layer optimization techniques, with a focus on the IEEE 802.11ac standard. A new multichannel aggregation scheme involving cross-knowledge between PHY and MAC layers has been proposed to improve performance in collision-prone environments. We have shown that some functionalities directly involved PHY and MAC layers. An accurate modeling of both PHY and MAC mechanisms is thus needed to have a realistic characterization of such functionalities. A cross-layer simulator, compliant with IEEE 802.11ac specifications, has thus been implemented. To the best of our knowledge, this is the first simulator incorporating detailed PHY and MAC functionalities for the IEEE 802.11ac standard. The multiple-user multiple-input, multiple-output (MU-MIMO) technique, which is one of the main innovations of the IEEE 802.11ac, needs both PHY and MAC layer considerations. We have thus used the implemented cross-layer simulator to evaluate the performance of MU-MIMO and compared it with the single-user MIMO (SU-MIMO). The aim of these studies was to evaluate the 'real' gains of MU-MIMO solutions (accounting for PHY+MAC) over SU-MIMO solutions and not the generally accepted ones. The impact of the channel sounding interval has particularly been studied. Finally, we have proposed a short PHY layer version of acknowledgment frames for overhead reduction in IEEE 802.11ah communications.

  2. A Cross-Layer PEP for DVB-RCS Networks

    NASA Astrophysics Data System (ADS)

    Giambene, Giovanni; Hadzic, Snezana

    The aim of this paper is to consider the problems of TCP performance in broadband GEO satellite networks and to propose a cross-layer approach for a transport-layer PEP that makes spoofing actions on ACKs to modify them in case the satellite network is congested. This approach is investigated here from the signaling standpoint with a special attention to the BSM reference model and considering a specific GEO satellite network architecture based on the DVB-S2/-RCS standards. The proposed PEP can prevent congestion in the satellite network, thus allowing a better TCP performance. This work has been carried out within the framework of the EU SatNEx II FP6 Network of Excellence.

  3. Crossing shock wave-turbulent boundary layer interactions

    NASA Technical Reports Server (NTRS)

    Narayanswami, N.; Knight, D. D.; Bogdonoff, S. M.; Horstman, C. C.

    1991-01-01

    Three-dimensional interactions between crossing shock waves generated by symmetric sharp fins and a turbulent boundary layer on a flat plate are investigated experimentally and theoretically at Mach number 2.95 and freestream unit Reynolds number 1.96 x 10 to the 7th/ft. The incoming boundary layer has a thickness of 4 mm at the location of the fin leading edges. A comparison of experimental and computational results for two sets of fin angles (11 x 11 and 9 x 9 deg) shows general agreement with regard to surface pressure measurements and surface streamline patterns. The principal feature of the streamline structure is a collision of counterrotating vortical structures emanating from near the fin leading edges and meeting at the geometric centerline of the interaction.

  4. Cross linking molecular systems to form ultrathin dielectric layers

    NASA Astrophysics Data System (ADS)

    Feng, Danqin

    Dehydrogenation leads to cross linking of polymer or polymer like formation in very different systems: self-assembled monolayers and in closo -carboranes leading to the formation of semiconducting and dielectric boron carbide. We find evidence of intermolecular interactions for a self-assembled monolayer (SAM) formed from a large molecular adsorbate, [1,1';4',1"-terphenyl]-4,4"-dimethanethiol, from the dispersion of the molecular orbitals with changing the wave vector k and from the changes with temperature. With the formation self assembled molecular (SAM) layer, the molecular orbitals hybridize to electronic bands, with indications of significant band dispersion of the unoccupied molecular orbitals. Although organic adsorbates and thin films are generally regarded as "soft" materials, the effective Debye temperature, indicative of the dynamic motion of the lattice normal to the surface, can be very high, e.g. in the multilayer film formed from [1,1'-biphenyl]-4,4'-dimethanethiol (BPDMT). Depending on molecular orientation, the effective Debye temperature can be comparable to that of graphite due to the 'stiffness' of the benzene rings, but follows the expected Debye-Waller behavior for the core level photoemission intensities with temperature. This is not always the case. We find that a monomolecular film formed from [1,1';4',1"-terphenyl]-4,4"-dimethanethiol deviates from Debye-Waller temperature behavior and is likely caused by temperature dependent changes in molecular orientation. We also find evidence for the increase in dielectric character with polymerization (cross-linking) in spite of the decrease in the HOMO-LUMO gap upon irradiation of TPDMT. The changes in the HOMO-LUMO gap, with cross-linking, are roughly consistent with the band dispersion. The decomposition and cross-linking processes are also accompanied by changes in molecular orientation. The energetics of the three isomeric carborane cage compounds [ closo-1,2-orthocarborane, closo-1

  5. Final report for CCS cross-layer reliability visioning study

    SciTech Connect

    Quinn, Heather M; Dehon, Andre; Carter, Nicj

    2010-12-20

    The geometric rate of improvement of transistor size and integrated circuit performance known as Moore's Law has been an engine of growth for our economy, enabling new products and services, creating new value and wealth, increasing safety, and removing menial tasks from our daily lives. Affordable, highly integrated components have enabled both life-saving technologies and rich entertainment applications. Anti-lock brakes, insulin monitors, and GPS-enabled emergency response systems save lives. Cell phones, internet appliances, virtual worlds, realistic video games, and mp3 players enrich our lives and connect us together. Over the past 40 years of silicon scaling, the increasing capabilities of inexpensive computation have transformed our society through automation and ubiquitous communications. Looking forward, increasing unpredictability threatens our ability to continue scaling integrated circuits at Moore's Law rates. As the transistors and wires that make up integrated circuits become smaller, they display both greater differences in behavior among devices designed to be identical and greater vulnerability to transient and permanent faults. Conventional design techniques expend energy to tolerate this unpredictability by adding safety margins to a circuit's operating voltage, clock frequency or charge stored per bit. However, the rising energy costs needed to compensate for increasing unpredictability are rapidly becoming unacceptable in today's environment where power consumption is often the limiting factor on integrated circuit performance and energy efficiency is a national concern. Reliability and energy consumption are both reaching key inflection points that, together, threaten to reduce or end the benefits of feature size reduction. To continue beneficial scaling, we must use a cross-layer, Jull-system-design approach to reliability. Unlike current systems, which charge every device a substantial energy tax in order to guarantee correct operation in

  6. Ice Layer Cross-Section In False Color

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The theme for the weeks of 1/17 and 1/24 is the north polar region of Mars as seen in false color THEMIS images. Ice/frost will typically appear as bright blue in color; dust mantled ice will appear in tones of red/orange.

    This image of shows a cross sectional view of the ice layers. Note the subtle peach banding on the left side of the image. The time variation that the bands represent is not yet understood.

    Image information: VIS instrument. Latitude 83.5, Longitude 118.2 East (241.8 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  7. Cross-layer design for decentralized detection in WSNs

    NASA Astrophysics Data System (ADS)

    Tantawy, Ashraf; Koutsoukos, Xenofon; Biswas, Gautam

    2014-12-01

    A wireless sensor network (WSN) deployed for detection applications has the distinguishing feature that the sensors cooperate to perform the detection task. Therefore, the decoupled and maximum throughput design approaches typically used to design communication networks do not lead to the desired optimal detection performance. Recent work on decentralized detection has addressed the design of media access control (MAC) and routing protocols for detection applications by considering independently the quality of information (QoI), channel state information (CSI), and residual energy information (REI) for each sensor. However, little attention has been given to integrate the three quality measures (QoI, CSI, and REI) in the system design. In this work, we present a cross-layer approach to design a QoI, CSI, and REI-aware transmission control policy (XCP) that coordinates communication between local sensors and the fusion center, in order to maximize the detection performance. We formulate and solve a constrained non-linear optimization problem to find the optimal XCP design variables, for both ALOHA and time-division multiple access (TDMA) sensor networks. We show the detection performance gain compared to the typical decoupled and maximum throughput design approaches, without utilizing additional network resources. We compare ALOHA and TDMA MAC schemes and show the conditions under which each transmission scheme outperforms.

  8. Inverted bulk-heterojunction solar cell with cross-linked hole-blocking layer

    PubMed Central

    Udum, Yasemin; Denk, Patrick; Adam, Getachew; Apaydin, Dogukan H.; Nevosad, Andreas; Teichert, Christian; S. White, Matthew.; S. Sariciftci, Niyazi.; Scharber, Markus C.

    2014-01-01

    We have developed a hole-blocking layer for bulk-heterojunction solar cells based on cross-linked polyethylenimine (PEI). We tested five different ether-based cross-linkers and found that all of them give comparable solar cell efficiencies. The initial idea that a cross-linked layer is more solvent resistant compared to a pristine PEI layer could not be confirmed. With and without cross-linking, the PEI layer sticks very well to the surface of the indium–tin–oxide electrode and cannot be removed by solvents used to process PEI or common organic semiconductors. The cross-linked PEI hole-blocking layer functions for multiple donor–acceptor blends. We found that using cross-linkers improves the reproducibility of the device fabrication process. PMID:24817837

  9. Inverted bulk-heterojunction solar cell with cross-linked hole-blocking layer.

    PubMed

    Udum, Yasemin; Denk, Patrick; Adam, Getachew; Apaydin, Dogukan H; Nevosad, Andreas; Teichert, Christian; S White, Matthew; S Sariciftci, Niyazi; Scharber, Markus C

    2014-05-01

    We have developed a hole-blocking layer for bulk-heterojunction solar cells based on cross-linked polyethylenimine (PEI). We tested five different ether-based cross-linkers and found that all of them give comparable solar cell efficiencies. The initial idea that a cross-linked layer is more solvent resistant compared to a pristine PEI layer could not be confirmed. With and without cross-linking, the PEI layer sticks very well to the surface of the indium-tin-oxide electrode and cannot be removed by solvents used to process PEI or common organic semiconductors. The cross-linked PEI hole-blocking layer functions for multiple donor-acceptor blends. We found that using cross-linkers improves the reproducibility of the device fabrication process. PMID:24817837

  10. Inverted bulk-heterojunction solar cell with cross-linked hole-blocking layer.

    PubMed

    Udum, Yasemin; Denk, Patrick; Adam, Getachew; Apaydin, Dogukan H; Nevosad, Andreas; Teichert, Christian; S White, Matthew; S Sariciftci, Niyazi; Scharber, Markus C

    2014-05-01

    We have developed a hole-blocking layer for bulk-heterojunction solar cells based on cross-linked polyethylenimine (PEI). We tested five different ether-based cross-linkers and found that all of them give comparable solar cell efficiencies. The initial idea that a cross-linked layer is more solvent resistant compared to a pristine PEI layer could not be confirmed. With and without cross-linking, the PEI layer sticks very well to the surface of the indium-tin-oxide electrode and cannot be removed by solvents used to process PEI or common organic semiconductors. The cross-linked PEI hole-blocking layer functions for multiple donor-acceptor blends. We found that using cross-linkers improves the reproducibility of the device fabrication process.

  11. Physical and Cross-Layer Security Enhancement and Resource Allocation for Wireless Networks

    ERIC Educational Resources Information Center

    Bashar, Muhammad Shafi Al

    2011-01-01

    In this dissertation, we present novel physical (PHY) and cross-layer design guidelines and resource adaptation algorithms to improve the security and user experience in the future wireless networks. Physical and cross-layer wireless security measures can provide stronger overall security with high efficiency and can also provide better…

  12. Spin and valley resolved Landau level crossing in tri-layer ABA stacked graphene

    NASA Astrophysics Data System (ADS)

    Datta, Biswajit; Gupta, Vishakha; Borah, Abhinandan; Watanabe, Kenji; Taniguchi, Takashi; Deshmukh, Mandar

    We present quantum Hall measurements on a high quality encapsulated tri-layer graphene device. Low temperature field effect mobility of this device is around 500,000 cm2/Vs and we see SdH oscillations at a magnetic field as low as 0.3 T. Quantum Hall measurements confirm that the chosen tri layer graphene is Bernal (ABA) stacked. Due to the presence of both mass-less monolayer like Dirac fermions and massive bi-layer like Dirac fermions in Bernal stacked tri-layer graphene, there are Landau level crossings between monolayer and bi-layer bands in quantum Hall regime. Although most of the Landau Level crossings are predominantly present on the electron sides, we also observe signatures of the crossings on the hole side. This behaviour is consistent with the asymmetry of electron and hole in ABA tri-layer graphene. We observe a series of crossings of the spin and valley resolved Landau Levels.

  13. The Balanced Cross-Layer Design Routing Algorithm in Wireless Sensor Networks Using Fuzzy Logic.

    PubMed

    Li, Ning; Martínez, José-Fernán; Hernández Díaz, Vicente

    2015-08-10

    Recently, the cross-layer design for the wireless sensor network communication protocol has become more and more important and popular. Considering the disadvantages of the traditional cross-layer routing algorithms, in this paper we propose a new fuzzy logic-based routing algorithm, named the Balanced Cross-layer Fuzzy Logic (BCFL) routing algorithm. In BCFL, we use the cross-layer parameters' dispersion as the fuzzy logic inference system inputs. Moreover, we give each cross-layer parameter a dynamic weight according the value of the dispersion. For getting a balanced solution, the parameter whose dispersion is large will have small weight, and vice versa. In order to compare it with the traditional cross-layer routing algorithms, BCFL is evaluated through extensive simulations. The simulation results show that the new routing algorithm can handle the multiple constraints without increasing the complexity of the algorithm and can achieve the most balanced performance on selecting the next hop relay node. Moreover, the Balanced Cross-layer Fuzzy Logic routing algorithm can adapt to the dynamic changing of the network conditions and topology effectively.

  14. The Balanced Cross-Layer Design Routing Algorithm in Wireless Sensor Networks Using Fuzzy Logic.

    PubMed

    Li, Ning; Martínez, José-Fernán; Hernández Díaz, Vicente

    2015-01-01

    Recently, the cross-layer design for the wireless sensor network communication protocol has become more and more important and popular. Considering the disadvantages of the traditional cross-layer routing algorithms, in this paper we propose a new fuzzy logic-based routing algorithm, named the Balanced Cross-layer Fuzzy Logic (BCFL) routing algorithm. In BCFL, we use the cross-layer parameters' dispersion as the fuzzy logic inference system inputs. Moreover, we give each cross-layer parameter a dynamic weight according the value of the dispersion. For getting a balanced solution, the parameter whose dispersion is large will have small weight, and vice versa. In order to compare it with the traditional cross-layer routing algorithms, BCFL is evaluated through extensive simulations. The simulation results show that the new routing algorithm can handle the multiple constraints without increasing the complexity of the algorithm and can achieve the most balanced performance on selecting the next hop relay node. Moreover, the Balanced Cross-layer Fuzzy Logic routing algorithm can adapt to the dynamic changing of the network conditions and topology effectively. PMID:26266412

  15. The Balanced Cross-Layer Design Routing Algorithm in Wireless Sensor Networks Using Fuzzy Logic

    PubMed Central

    Li, Ning; Martínez, José-Fernán; Díaz, Vicente Hernández

    2015-01-01

    Recently, the cross-layer design for the wireless sensor network communication protocol has become more and more important and popular. Considering the disadvantages of the traditional cross-layer routing algorithms, in this paper we propose a new fuzzy logic-based routing algorithm, named the Balanced Cross-layer Fuzzy Logic (BCFL) routing algorithm. In BCFL, we use the cross-layer parameters’ dispersion as the fuzzy logic inference system inputs. Moreover, we give each cross-layer parameter a dynamic weight according the value of the dispersion. For getting a balanced solution, the parameter whose dispersion is large will have small weight, and vice versa. In order to compare it with the traditional cross-layer routing algorithms, BCFL is evaluated through extensive simulations. The simulation results show that the new routing algorithm can handle the multiple constraints without increasing the complexity of the algorithm and can achieve the most balanced performance on selecting the next hop relay node. Moreover, the Balanced Cross-layer Fuzzy Logic routing algorithm can adapt to the dynamic changing of the network conditions and topology effectively. PMID:26266412

  16. Hypersonic crossing shock-wave/turbulent-boundary-layer interactions

    NASA Technical Reports Server (NTRS)

    Kussoy, M. I.; Horstman, K. C.; Horstman, C. C.

    1993-01-01

    Experimental data for two three-dimensional intersecting shock-wave/turbulent boundary-layer interaction flows at Mach 8.3 are presented. The test bodies, composed of two sharp fins fastened to a flat plate test bed, were designed to generate flows with varying degrees of pressure gradient, boundary-layer separation, and turning angle. The data include surface pressure and heat transfer distributions as well as mean flow field surveys both in the undisturbed and interaction regimes. The data are presented in a convenient form to be used to validate existing or future computational models of these hypersonic flows.

  17. Electric and Magnetic Field and Plasma Density Measurements During Multiple Dayside Boundary Layer Crossings On Cluster

    NASA Astrophysics Data System (ADS)

    Pedersen, A.; Denig, W. F.; Lucek, E.; Lybekk, B.; Moen, J.; Oksavik, K.; Svenes, K.; Vaivads, A.

    Cluster observed multiple crossings of the dayside boundary layer on 26.January 2001 when the four spacecraft orbited out between 12 and 13 Earth radii near 15 h local time. The magnetic latitude of Cluster varied between 50 and 44 degrees, which meant that the spacecraft were conjugated with the frontside cusp or cleft at ionospheric al- titudes. The solar wind magnetic field was initially southward and then turned to a steady value in the -Y direction during the boundary layer crossings. Electric and magnetic field measurements and calculated E x B velocities, together with high time resolution plasma density information from spacecraft potential measurements, will be used to describe the boundary layer crossings. Data from near Earth polar orbiting spacecraft and from ground networks will be used to provide complementary infor- mation of the polar and cusp conditions during the Cluster boundary layer crossings.

  18. Nonlinear stability of non-stationary cross-flow vortices in compressible boundary layers

    NASA Technical Reports Server (NTRS)

    Gajjar, J. S. B.

    1995-01-01

    The nonlinear evolution of long wavelength non-stationary cross-flow vortices in a compressible boundary layer is investigated and the work extends that of Gajjar (1994) to flows involving multiple critical layers. The basic flow profile considered in this paper is that appropriate for a fully three-dimensional boundary layer with O(1) Mach number and with wall heating or cooling. The governing equations for the evolution of the cross-flow vortex are obtained and some special cases are discussed. One special case includes linear theory where exact analytic expressions for the growth rate of the vortices are obtained. Another special case is a generalization of the Bassom & Gajjar (1988) results for neutral waves to compressible flows. The viscous correction to the growth rate is derived and it is shown how the unsteady nonlinear critical layer structure merges with that for a Haberman type of viscous critical layer.

  19. Nanomechanics of layer-by-layer polyelectrolyte complexes: a manifestation of ionic cross-links and fixed charges.

    PubMed

    Han, Biao; Chery, Daphney R; Yin, Jie; Lu, X Lucas; Lee, Daeyeon; Han, Lin

    2016-01-28

    This study investigates the roles of two distinct features of ionically cross-linked polyelectrolyte networks - ionic cross-links and fixed charges - in determining their nanomechanical properties. The layer-by-layer assembled poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA) network is used as the model material. The densities of ionic cross-links and fixed charges are modulated through solution pH and ionic strength (IS), and the swelling ratio, elastic and viscoelastic properties are quantified via an array of atomic force microscopy (AFM)-based nanomechanical tools. The roles of ionic cross-links are underscored by the distinctive elastic and viscoelastic nanomechanical characters observed here. First, as ionic cross-links are highly sensitive to solution conditions, the instantaneous modulus, E0, exhibits orders-of-magnitude changes upon pH- and IS-governed swelling, distinctive from the rubber elasticity prediction based on permanent covalent cross-links. Second, ionic cross-links can break and self-re-form, and this mechanism dominates force relaxation of PAH/PAA under a constant indentation depth. In most states, the degree of relaxation is >90%, independent of ionic cross-link density. The importance of fixed charges is highlighted by the unexpectedly more elastic nature of the network despite low ionic cross-link density at pH 2.0, IS 0.01 M. Here, the complex is a net charged, loosely cross-linked, where the degree of relaxation is attenuated to ≈50% due to increased elastic contribution arising from fixed charge-induced Donnan osmotic pressure. In addition, this study develops a new method for quantifying the thickness of highly swollen polymer hydrogel films. It also underscores important technical considerations when performing nanomechanical tests on highly rate-dependent polymer hydrogel networks. These results provide new insights into the nanomechanical characters of ionic polyelectrolyte complexes, and lay the ground for further

  20. Flow field measurements in a crossing shockwave turbulent boundary layer interaction at Mach 3

    NASA Technical Reports Server (NTRS)

    Lachowicz, Jason T.; Chokani, Ndaona

    1993-01-01

    An experimental study has been conducted to examine the flow field of the 3D crossing shock wave/turbulent boundary layer interaction. A symmetric pair of 9-deg fins were used to generate the crossing shocks. The incoming boundary layer was developed on the tunnel sidewall and thus was relatively thick, 0.49 arcsec, and suited for pitot probe surveys. The test conditions were a nominal Mach number of 3 and unit Reynolds number of 1.2 x 10 exp 7/ft. The measurements obtained included surface oil flow visualizations, surface static pressures, and boundary layer pitot pressure profiles. The results showed that downstream of the crossing shock intersection, the stagnation pressure losses were significant and the stagnation pressure profiles were highly nonuniform. Despite the severe shock disturbances, the law of the wall and the law of the wake were found to give relatively good agreement with the experimental data.

  1. Ambient Intelligence Context-Based Cross-Layer Design in Wireless Sensor Networks

    PubMed Central

    Liu, Yang; Seet, Boon-Chong; Al-Anbuky, Adnan

    2014-01-01

    By exchanging information directly between non-adjacent protocol layers, cross-layer (CL) interaction can significantly improve and optimize network performances such as energy efficiency and delay. This is particularly important for wireless sensor networks (WSNs) where sensor devices are energy-constrained and deployed for real-time monitoring applications. Existing CL schemes mainly exploit information exchange between physical, medium access control (MAC), and routing layers, with only a handful involving application layer. For the first time, we proposed a framework for CL optimization based on user context of ambient intelligence (AmI) application and an ontology-based context modeling and reasoning mechanism. We applied the proposed framework to jointly optimize MAC and network (NET) layer protocols for WSNs. Extensive evaluations show that the resulting optimization through context awareness and CL interaction for both MAC and NET layer protocols can yield substantial improvements in terms of throughput, packet delivery, delay, and energy performances. PMID:25317760

  2. A Survey on Multimedia-Based Cross-Layer Optimization in Visual Sensor Networks

    PubMed Central

    Costa, Daniel G.; Guedes, Luiz Affonso

    2011-01-01

    Visual sensor networks (VSNs) comprised of battery-operated electronic devices endowed with low-resolution cameras have expanded the applicability of a series of monitoring applications. Those types of sensors are interconnected by ad hoc error-prone wireless links, imposing stringent restrictions on available bandwidth, end-to-end delay and packet error rates. In such context, multimedia coding is required for data compression and error-resilience, also ensuring energy preservation over the path(s) toward the sink and improving the end-to-end perceptual quality of the received media. Cross-layer optimization may enhance the expected efficiency of VSNs applications, disrupting the conventional information flow of the protocol layers. When the inner characteristics of the multimedia coding techniques are exploited by cross-layer protocols and architectures, higher efficiency may be obtained in visual sensor networks. This paper surveys recent research on multimedia-based cross-layer optimization, presenting the proposed strategies and mechanisms for transmission rate adjustment, congestion control, multipath selection, energy preservation and error recovery. We note that many multimedia-based cross-layer optimization solutions have been proposed in recent years, each one bringing a wealth of contributions to visual sensor networks. PMID:22163908

  3. Performance analysis of STT-RAM with cross shaped free layer using Heusler alloys

    NASA Astrophysics Data System (ADS)

    Bharat Kumary, Tangudu; Ghosh, Bahniman; Awadhiya, Bhaskar; Verma, Ankit Kumar

    2016-01-01

    We have investigated the performance of a spin transfer torque random access memory (STT-RAM) cell with a cross shaped Heusler compound based free layer using micromagnetic simulations. We have designed a free layer using a Cobalt based Heusler compound. Simulation results clearly show that the switching time from one state to the other state has been reduced, also it has been found that the critical switching current density (to switch the magnetization of the free layer of the STT RAM cell) is reduced.

  4. Electrostatic modulation and enzymatic cross-linking of interfacial layers impacts gastrointestinal fate of multilayer emulsions.

    PubMed

    Zeeb, Benjamin; Weiss, Jochen; McClements, David Julian

    2015-08-01

    In this study, membrane properties were modulated using layer-by-layer electrostatic depositioning in combination with salt and/or enzyme treatment to control the gastrointestinal fate of emulsified oils. Lipid droplets coated by a single-layer of biopolymers (gelatin) were prepared by high pressure homogenization. Lipid droplets coated by a double-layer of biopolymers (gelatin-pectin) were prepared by electrostatically depositing sugar beet pectin on the gelatin-coated droplets. Laccase was added to the double-layer emulsions to covalently crosslink the adsorbed pectin molecules, whereas sodium chloride was added to modulate interfacial properties through electrostatic screening effects. Non-cross-linked and cross-linked double-layer emulsions (with and without salt) were then passed through a simulated gastrointestinal tract (GIT) that included mouth, gastric and intestinal phases. Free fatty acid release profiles suggested that the stability of the emulsified droplets within the GIT played a more important role in determining the rate and extent of lipid digestion than the initial interfacial layer properties.

  5. Electrostatic modulation and enzymatic cross-linking of interfacial layers impacts gastrointestinal fate of multilayer emulsions.

    PubMed

    Zeeb, Benjamin; Weiss, Jochen; McClements, David Julian

    2015-08-01

    In this study, membrane properties were modulated using layer-by-layer electrostatic depositioning in combination with salt and/or enzyme treatment to control the gastrointestinal fate of emulsified oils. Lipid droplets coated by a single-layer of biopolymers (gelatin) were prepared by high pressure homogenization. Lipid droplets coated by a double-layer of biopolymers (gelatin-pectin) were prepared by electrostatically depositing sugar beet pectin on the gelatin-coated droplets. Laccase was added to the double-layer emulsions to covalently crosslink the adsorbed pectin molecules, whereas sodium chloride was added to modulate interfacial properties through electrostatic screening effects. Non-cross-linked and cross-linked double-layer emulsions (with and without salt) were then passed through a simulated gastrointestinal tract (GIT) that included mouth, gastric and intestinal phases. Free fatty acid release profiles suggested that the stability of the emulsified droplets within the GIT played a more important role in determining the rate and extent of lipid digestion than the initial interfacial layer properties. PMID:25766826

  6. Cross-layer restoration with software defined networking based on IP over optical transport networks

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Cheng, Lei; Deng, Junni; Zhao, Yongli; Zhang, Jie; Lee, Young

    2015-10-01

    The IP over optical transport network is a very promising networking architecture applied to the interconnection of geographically distributed data centers due to the performance guarantee of low delay, huge bandwidth and high reliability at a low cost. It can enable efficient resource utilization and support heterogeneous bandwidth demands in highly-available, cost-effective and energy-effective manner. In case of cross-layer link failure, to ensure a high-level quality of service (QoS) for user request after the failure becomes a research focus. In this paper, we propose a novel cross-layer restoration scheme for data center services with software defined networking based on IP over optical network. The cross-layer restoration scheme can enable joint optimization of IP network and optical network resources, and enhance the data center service restoration responsiveness to the dynamic end-to-end service demands. We quantitatively evaluate the feasibility and performances through the simulation under heavy traffic load scenario in terms of path blocking probability and path restoration latency. Numeric results show that the cross-layer restoration scheme improves the recovery success rate and minimizes the overall recovery time.

  7. Coherent structures generated by a circular jet issuing into a cross laminar boundary layer

    NASA Astrophysics Data System (ADS)

    Brizzi, L. E.; Bousgarbiès, J. L.; Foucault, E.

    1997-06-01

    Visualisations by LASER topographies and velocity measurements by LDV have allowed the study of the flow resulting from the interaction between a circular jet and a cross boundary layer. This type of flow is dominated by the presence of many complex vortices that come from the recombining of the vorticity created in the injection tube and that created along the chamber floor.

  8. IEEE 802.16 Packet Scheduling with Traffic Prioritization and Cross-Layer Optimization

    NASA Astrophysics Data System (ADS)

    Monteiro, João; Sargento, Susana; Gomes, Álvaro; Fontes, Francisco; Neves, Pedro

    WiMAX is emerging as a broadband wireless access technology to satisfy end user expectations, containing a new set of advantages in terms of throughput, coverage and QoS support at the MAC level which allows convergence of several different types of applications and services. For that reason, the allocation of resources or scheduling becomes of greater importance. This paper focuses on a cross-layer scheduling optimization solution for IEEE 802.16. The relevant features of the proposed packet scheduling optimization scheme consist: of prioritization of users within the same traffic class, allowing for example to an operator, differentiated treatment among users, for instance distinguishing between premium or gold users and silver users; and also cross layer optimization which implies radio resource optimization and a more effective scheduler decision. Simulation scenarios are presented to demonstrate how the scheduling solution allocates resources through particular WiMAX MAC layer implementation in the NS-2 simulator. Results show that the new mechanism implementation results in an improvement to the simple Round Robin fashion present in the original simulation model, being able to increase differentiation between different classes and decrease packets delay, due to its cross-layer processing and traffic prioritization.

  9. Cross-layer design for prompt and reliable transmissions over body area networks.

    PubMed

    Torabi, Narjes; Leung, Victor C M

    2014-07-01

    In this paper, we propose a cross-layer design to make ambulatory health monitoring via body area networks (BAN) more reliable and robust. The proposed design builds on our centralized body area network access scheme (CBAS), a receiver-initiated medium access control (MAC) scheme that improves the visibility of a BAN in a coexistent environment, where diverse networks with various physical and MAC protocols share the radio spectrum. The design enhances CBAS by incorporating a network layer scheme that improves the packet delivery ratio (PDR), while minimizing the need for multihop cooperative transmissions; thus, packet delay is less compromised to achieve higher PDRs. The MAC layer provides the network layer with local information about the quality of on-body links to enable the BAN to identify the most reliable links in a distributed manner. Extensive experimental results are presented, which give insights on how the proposed cross-layer design improves PDR and packet delay. Results show the effectiveness of the proposed design which takes advantage of dynamic scheduling and multihop relays as warranted by the link conditions. PMID:24132027

  10. Vision for cross-layer optimization to address the dual challenges of energy and reliability

    SciTech Connect

    Quinn, Heather M; Dehon, Andre; Carter, Nicholas P

    2009-01-01

    We are rapidly approaching an inflection point where the conventional target of producing perfect, identical transistors that operate without upset can no longer be maintained while continuing to reduce the energy per operation. With power requirements already limiting chip performance, continuing to demand perfect, upset-free transistors would mean the end of scaling benefits. The big challenges in device variability and reliability are driven by uncommon tails in distributions, infrequent upsets, one-size-fits-all technology requirements, and a lack of information about the context of each operation. Solutions co-designed across traditional layer boundaries in our system stack can change the game, allowing architecture and software (a) to compensate for uncommon variation, environments, and events, (b) to pass down invariants and requirements for the computation, and (c) to monitor the health of collections of deVices. Cross-layer codesign provides a path to continue extracting benefits from further scaled technologies despite the fact that they may be less predictable and more variable. While some limited multi-layer mitigation strategies do exist, to move forward redefining traditional layer abstractions and developing a framework that facilitates cross-layer collaboration is necessary.

  11. Cross-layer design for prompt and reliable transmissions over body area networks.

    PubMed

    Torabi, Narjes; Leung, Victor C M

    2014-07-01

    In this paper, we propose a cross-layer design to make ambulatory health monitoring via body area networks (BAN) more reliable and robust. The proposed design builds on our centralized body area network access scheme (CBAS), a receiver-initiated medium access control (MAC) scheme that improves the visibility of a BAN in a coexistent environment, where diverse networks with various physical and MAC protocols share the radio spectrum. The design enhances CBAS by incorporating a network layer scheme that improves the packet delivery ratio (PDR), while minimizing the need for multihop cooperative transmissions; thus, packet delay is less compromised to achieve higher PDRs. The MAC layer provides the network layer with local information about the quality of on-body links to enable the BAN to identify the most reliable links in a distributed manner. Extensive experimental results are presented, which give insights on how the proposed cross-layer design improves PDR and packet delay. Results show the effectiveness of the proposed design which takes advantage of dynamic scheduling and multihop relays as warranted by the link conditions.

  12. Layer-crossing overhead and information spreading in multiplex social networks

    NASA Astrophysics Data System (ADS)

    Min, Byungjoon; Goh, K.-I.

    2014-03-01

    Many real-world systems consist of multiple different layers of networks and interplay between them. Taking such multiplexity into account is important to a complete understanding of the structure and dynamics of complex systems. In this respect, we propose and study a model of information or disease spreading on multiplex social networks, in which agents interact or communicate through multiple channels (layers), and there exists a layer-switching overhead for transmission across the interaction layers. The model is characterized by the path-dependent transmissibility over a contact, which is dynamically determined, dependent on both incoming and outgoing transmission layers due to the switching overhead. We formulate a generalized theory with a mapping to deal with such a path-dependent transmissibility, and demonstrate dependency of epidemic threshold and epidemic outbreak size with respect to multiplexity characteristics such as the densities of network layers, layer-crossing costs, and type of seed infections. Our results suggest that explicit consideration of multiplexity can be crucial in realistic modeling of spreading processes on social networks.

  13. Cross-Field Current Instabilities in Thin Ionization Layers and the Enhanced Aurora

    SciTech Connect

    Jay R. Johnson and Hideo Okuda

    2008-05-20

    Nearly half of the time, auroral displays exhibit thin, bright layers known as \\enhanced aurora." There is a substantial body of evidence that connects these displays with thin, dense, heavy ion layers in the E-region. Based on the spectral characteristics of the enhanced layers, it is believed that they result when wave-particle interaction heats ambient electrons to energies at or just above the 17 eV ionization energy of N2. While there are several possible instabilities that could produce suprathermal electrons in thin layers, there has been no clear theoretical investigation which examines in detail how wave instabilities in the thin ionization layers could develop and produce the suprathermal electrons. We examine instabilities which would occur in thin, dense, heavy ion layers using extensive analytical analysis combined with particle simulations. We analyze a cross field current instability that is found to be strongly unstable in the heavy ion layers. Electrostatic simulations show that substantial heating of the ambient electrons occurs with energization at or above the N2 ionization energy.

  14. Preliminary study of the interactions caused by crossing shock waves and a turbulent boundary layer

    NASA Technical Reports Server (NTRS)

    Ketchum, A. C.; Bogdonoff, S. M.; Fernando, E. M.; Batcho, P. F.

    1989-01-01

    The subject research, the first phase of an extended study of the interaction of crossing shock waves with a turbulent boundary layer, has revealed the complexity of the resulting flow. Detailed surface visualization and mean wall static pressure distributions show little resemblance to the inviscid flow approximation, and the exploratory high frequency measurements show that the flow downstream of the theoretical inviscid shock crossing position has a significant unsteady characteristic. Further developments of the (unsteady) high frequency measurements are required to fully characterize the unsteadiness and the requirements to include this component in flowfield modeling.

  15. The Study of Cross-layer Optimization for Wireless Rechargeable Sensor Networks Implemented in Coal Mines.

    PubMed

    Ding, Xu; Shi, Lei; Han, Jianghong; Lu, Jingting

    2016-01-28

    Wireless sensor networks deployed in coal mines could help companies provide workers working in coal mines with more qualified working conditions. With the underground information collected by sensor nodes at hand, the underground working conditions could be evaluated more precisely. However, sensor nodes may tend to malfunction due to their limited energy supply. In this paper, we study the cross-layer optimization problem for wireless rechargeable sensor networks implemented in coal mines, of which the energy could be replenished through the newly-brewed wireless energy transfer technique. The main results of this article are two-fold: firstly, we obtain the optimal relay nodes' placement according to the minimum overall energy consumption criterion through the Lagrange dual problem and KKT conditions; secondly, the optimal strategies for recharging locomotives and wireless sensor networks are acquired by solving a cross-layer optimization problem. The cyclic nature of these strategies is also manifested through simulations in this paper.

  16. Performance Comparison of Cross-Like Hall Plates with Different Covering Layers

    PubMed Central

    Lyu, Fei; Zhang, Zhenyan; Toh, Eng-Huat; Liu, Xinfu; Ding, Yinjie; Pan, Yifan; Li, Chengjie; Li, Li; Sha, Jin; Pan, Hongbing

    2015-01-01

    This paper studies the effects of the covering layers on the performance of a cross-like Hall plate. Three different structures of a cross-like Hall plate in various sizes are designed and analyzed. The Hall plate sensitivity and offset are characterized using a self-built measurement system. The effect of the P-type region over the active area on the current-related sensitivity is studied for different Hall plate designs. In addition, the correlation between the P-type covering layer and offset is analyzed. The best structure out of three designs is determined. Besides, a modified eight-resistor circuit model for the Hall plate is presented with improved accuracy by taking the offset into account. PMID:25559001

  17. The Study of Cross-layer Optimization for Wireless Rechargeable Sensor Networks Implemented in Coal Mines

    PubMed Central

    Ding, Xu; Shi, Lei; Han, Jianghong; Lu, Jingting

    2016-01-01

    Wireless sensor networks deployed in coal mines could help companies provide workers working in coal mines with more qualified working conditions. With the underground information collected by sensor nodes at hand, the underground working conditions could be evaluated more precisely. However, sensor nodes may tend to malfunction due to their limited energy supply. In this paper, we study the cross-layer optimization problem for wireless rechargeable sensor networks implemented in coal mines, of which the energy could be replenished through the newly-brewed wireless energy transfer technique. The main results of this article are two-fold: firstly, we obtain the optimal relay nodes’ placement according to the minimum overall energy consumption criterion through the Lagrange dual problem and KKT conditions; secondly, the optimal strategies for recharging locomotives and wireless sensor networks are acquired by solving a cross-layer optimization problem. The cyclic nature of these strategies is also manifested through simulations in this paper. PMID:26828500

  18. Charge regulation and energy dissipation while compressing and sliding a cross-linked chitosan hydrogel layer.

    PubMed

    Liu, Chao; Thormann, Esben; Tyrode, Eric; Claesson, Per M

    2015-04-01

    Interactions between a silica surface and a surface coated with a grafted cross-linked hydrogel made from chitosan/PAA multilayers are investigated, utilizing colloidal probe atomic force microscopy. Attractive double-layer forces are found to dominate the long-range interaction over a broad range of pH and ionic strength conditions. The deduced potential at the hydrogel/aqueous interface is found to be very low. This situation is maintained in the whole pH-range investigated, even though the degree of protonation of chitosan changes significantly. This demonstrates that pH-variations change the concentration of counterions within the hydrogel to keep the interior close to uncharged, which is similar to what has been observed for polyelectrolyte brushes. Changes in pH and ionic strength affect the adhesion force and the friction force between the silica surface and the hydrogel layer, but not the friction coefficient. This suggests that the main energy dissipation mechanism arises from processes occurring within the hydrogel layer, rather than at the silica/hydrogel interface, and we suggest that it is related to stretching of polymer chains between the cross-linking points. We also find that an increased cross-linking density, from 40% to 100%, in the hydrogel reduces the friction coefficient.

  19. Ultrathin, biomimetic, superhydrophilic layers of cross-linked poly(phosphobetaine) on polyethylene by photografting.

    PubMed

    Yang, Biao; Duan, Xiaobo; Huang, Jijun

    2015-01-27

    Ultrathin, biomimetic, superhydrophilic hydrogel layers, composed of cross-linked poly(2-methacryloyloxyethyl phosphorylcholine), are formed on low-density polyethylene films via ultraviolet-initiated surface graft polymerization. The layers are 19-58 nm thick as revealed by electron microscopy and have three-dimensional networks; the unique network structure, along with its zwitterionic nature, rather than surface roughness results in superhydrophilicity, that is, the water contact angle around 5°. This superhydrophilicity depends on a variety of factors, including the concentration of the monomer and cross-linker, the type of reaction solvents, the reaction and drying time, the intensity of UV light, and the way of measurement of water contact angles. Superhydrophilicity is obtained under a fixed ratio (e.g., 1/1) of the monomer to cross-linker, a reaction time over 120 s, a short drying time, (75%) ethanol as the reaction solvent, and low-intensity UV light, largely because these factors together generate optimal three-dimensional networks of cross-links.

  20. Experimental Investigation of Crossing Shock Wave-Turbulent Boundary Layer-Bleed Interaction

    NASA Technical Reports Server (NTRS)

    Kim, Hyun; Hingst, Warren R.; Davis, David O.

    1996-01-01

    Results of an experimental investigation of a symmetric crossing shock wave/turbulent boundary layer/bleed interaction are presented for a freestream unit Reynolds number of 1.68 x 10(exp 7)/m, a Mach number of 2.81, and deflection angles of 8 degrees. The data obtained in this study are bleed mass flow rate using a trace gas technique, qualitative information in the form of oil flow visualization, flow field Pitot pressures, and static pressure measurements using pressure sensitive paint. The main objective of this test is two-fold. First, this study is conducted to explore boundary layer control through mass flow removal near a large region of separated flow caused by the interaction of a double fin-induced shock wave and an incoming turbulent boundary layer. Also, a comprehensive data set is needed for computational fluid dynamics code validation.

  1. Transient Ultrasonic Guided Waves in Bi-Layered Anisotropic Plates with Rectangular Cross Section

    NASA Astrophysics Data System (ADS)

    Mukdadi, O. M.; Datta, S. K.

    2004-02-01

    Transient ultrasonic guided waves in anisotropic bi-layered plates with finite-width are investigated in this paper. Composite bi-layered plates consisting of GaAs substrate coated with Nb sheath is considered as an example because of its application to electronics and calorimetry. The purpose is to investigate the acoustic mode coupling ("pinching") phenomena for phonon transport. A semi-analytical finite element (SAFE) method is adopted to study the guided wave dispersion behavior in finite-width elastic plates. Nine-noded quadrilateral elements are used to model the cross section of the finite-width plate. Propagation in the axial direction is modeled by analytical wave functions. Elastodynamic Green's functions are derived using modal summation in the frequency-wavenumber and time-space domains. Results for dispersion and transient analysis of guided waves in finite-width plates are presented and compared for different aspect ratios. Group velocities are calculated and wave arrival times are computed for different plate cross sections as well as different excitation frequency. Numerical results show significant influence of the plate aspect ratio on the dispersion and transient wave response. Complex nature of quasi-mode dispersion and propagation due to pinching phenomena in anisotropic plates require such quantitative analysis to afford easy interpretation. These results would be important for nondestructive material evaluation and for characterization of phonon transport in anisotropic bi-layered plates.

  2. The Interaction of a Circular Synthetic Jet with a Cross-Flow Boundary Layer

    SciTech Connect

    D. M. McEligot; R. J. Pink; Jennifer M. Shuster; Douglas R. Smith

    2005-06-01

    The interaction of a circular synthetic jet with a laminar cross-flow boundary layer was investigated experimentally in the Matched-Index-of-Refraction flow facility at Idaho National Laboratory. Two orifice orientations were investigated, straight and inclined. For each orifice, phase-averaged and time-averaged PIV measurements were made at L◦/D◦ = 1.0 and 2.0 with ReU◦ = 250 and r = 1.12. Refractive index matching between the working fluid and the model material permitted experimental measurements of the flow field inside the actuator orifice and cavity simultaneously. At L◦/D◦ = 1.0, the vortex ring formed at the orifice during the expulsion portion of the actuator cycle blocks the boundary layer causing the flow to divert over and around the ring. This vortex ring does not escape the near-vicinity of the orifice and is subsequently re-ingested. At the same stroke, inclining the orifice axis 30◦ downstream leads to a jet comprised of a train of vortex rings that penetrates the cross-flow. At L◦/D◦ = 2.0, both the straight and inclined orifices create large discrete vortex rings that penetrate deep into the cross-flow, and consequently do not affect the boundary layer much beyond the near-field of the orifice.

  3. Ladder and cross terms in second-order distorted Born approximation. [for bounded layer of random discrete scatterers

    NASA Technical Reports Server (NTRS)

    Jin, Y. Q.; Kong, J. A.

    1985-01-01

    In the strong fluctuation theory for a bounded layer of random discrete scatterers, the second moments of the fields in the second-order distorted Born approximation are obtained for copolarized and cross-polarized fields. The backscattering cross sections per unit area are calculated by including the mutual coherence of the fields due to the coincidental ray paths, and that due to the opposite ray paths, corresponding to the ladder and cross terms in the Feynman diagramatic representation. It is proved that the contributions from ladder and cross terms for the copolarized backscattering cross sections are the same, while the contributions for the cross-polarized backscattering cross sections are of the same order. The bistatic scattering coefficients in the second-order approximation for both the ladder and cross terms are also obtained. The contributions from the cross terms explain the enhancement in the backscattering direction.

  4. Computation of crossing shock/turbulent boundary layer interaction at Mach 8.3

    NASA Technical Reports Server (NTRS)

    Narayanswami, N.; Horstman, C. C.; Knight, D. D.

    1993-01-01

    A three-dimensional (3D) hypersonic crossing shock wave/turbulent boundary-layer interaction is examined numerically at Mach 8.3. The test geometry consists of a pair of opposing sharp fins of angle alpha = 15 deg, mounted on a flat plate. Two theoretical models are evaluated. The full (3D) Reynolds-averaged Navier-Stokes equations are solved using the Baldwin-Lomax and the Rodi (modified k-epsilon) turbulence models. Computed results for both cases show good agreement with experiment for flat plate surface pressure and for flowfield profiles of pitot pressure and yaw angle, indicating that the flowfield is primarily rotational and inviscid. Fair to poor agreement is obtained for surface heat transfer, indicating a need for more accurate turbulence models. The overall flowfield structure is similar to that observed in previous crossing shock interaction studies.

  5. A study of the unsteadiness of crossing shock wave turbulent boundary layer interactions

    NASA Technical Reports Server (NTRS)

    Poddar, K.; Bogdonoff, S. M.

    1990-01-01

    The unsteadiness of crossing shock wave turbulent boundary layer interactions at a nominal Mach number of 3 was examined by measuring wall pressure fluctuations using multiple, high frequency response, pressure transducers. The unsteadiness in the initial part of the interaction for all the interactions is similar to that of single fin interaction as studied by Tran and Bogdonoff (1987). However, for stronger interactions, flow downstream of the inviscid shock crossing position has a significant unsteady characteristic. In this unsteady region of the interaction, mean surface pressure rises significantly over the value obtained from the inviscid shock approximation. The energy spectrum of the fluctuating pressure signal shows a significant increase in the energy level at the higher frequencies.

  6. The 3-D Navier-Stokes analysis of crossing, glancing shocks/turbulent boundary layer interactions

    NASA Technical Reports Server (NTRS)

    Reddy, D. R.

    1991-01-01

    Three dimensional viscous flow analysis is performed for a configuration where two crossing and glancing shocks interact with a turbulent boundary layer. A time marching 3-D full Navier-Stokes code, called PARC3D, is used to compute the flow field, and the solution is compared to the experimental data obtained at the NASA Lewis Research Center's 1 x 1 ft supersonic wind tunnel facility. The study is carried out as part of the continuing code assessment program in support of the generic hypersonic research at NASA Lewis. Detailed comparisons of static pressure fields and oil flow patterns are made with the corresponding solution on the wall containing the shock/boundary layer interaction in an effort to validate the code for hypersonic inlet applications.

  7. 3-D Navier-Stokes analysis of crossing, glancing shocks/turbulent boundary layer interactions

    NASA Technical Reports Server (NTRS)

    Reddy, D. R.

    1991-01-01

    Three dimensional viscous flow analysis is performed for a configuration where two crossing and glancing shocks interact with a turbulent boundary layer. A time marching 3-D full Navier-Stokes code, called PARC3D, is used to compute the flow field, and the solution is compared to the experimental data obtained at the NASA Lewis Research Center's 1 x 1 ft supersonic wind tunnel facility. The study is carried out as part of the continuing code assessment program in support of the generic hypersonic research at NASA Lewis. Detailed comparisons of static pressure fields and oil flow patterns are made with the corresponding solution on the wall containing the shock/boundary layer interaction in an effort to validate the code for hypersonic inlet applications.

  8. Cross-plane heat transfer through single-layer carbon structures.

    PubMed

    Zhang, Huaichen; Nedea, Silvia V; Rindt, Camilo C M; Smeulders, David M J

    2016-02-21

    Graphene-based nano-structures have been recently proposed to function as additives to improve the conductivity of thermally sluggish phase change materials (PCMs). Based on the existing research studies, the improvement is dependent not only on the matrix material, but also on the geometry of the carbon structure. To gain more insight into the nano-scale thermal transport problem, we launched the current pilot research using water as the matrix material, to represent the hydroxyl-group-rich sugar alcohols as PCMs. We have found that the heat conduction across a graphene layer to water is much faster than the heat conduction to the graphene layer itself. Also, the high graphene-water thermal contact resistance fails to acknowledge the fast thermal kinetics of the low frequency phonons. In the investigation of the geometry effect, the cross-plane heat transfer coefficient is found to decrease with decreasing CNT diameter except CNT(9,9). PMID:26818392

  9. Surface and flow field measurements in a symmetric crossing shock wave/turbulent boundary layer flow

    NASA Technical Reports Server (NTRS)

    Davis, D. O.; Hingst, W. R.

    1992-01-01

    Results of an experimental investigation of a symmetric crossing shock/turbulent boundary layer interaction are presented for a Mach number of 3.44 and deflections angles of 2, 6, 8 and 9 deg. The interaction strengths vary from weak to strong enough to cause a large region of separated flow. Measured quantities include surface static pressure and flowfield Pitot pressures. Pitot profiles in the plane of symmetry through the interaction region are shown for various deflection angles. Oil flow visualization and the results of a trace gas streamline tracking technique are also presented.

  10. Study of cross-spectra of velocity components and temperature series in a nocturnal boundary layer

    NASA Astrophysics Data System (ADS)

    Maqueda, Gregorio; Sastre, Mariano; Viñas, Carmen; Viana, Samuel; Yagüe, Carlos

    2010-05-01

    The main characteristic of the Planetary Boundary Layer is the turbulent flow that can be understood as the motions of many superimposed eddies with different scales, which are very irregular and produce mixing among the atmospheric properties. Spectral analysis is a widely used statistical tool to know the size of eddies into the flow. The Turbulent Kinetic Energy is split in fractions for each scale of eddy by mean the power spectrum of the wind velocity components. Also, the fluctuation of the other variables as temperature, humidity, gases concentrations or material particles presents in the atmosphere can be divided according to the importance of different scales in a similar way than the wind. A Cross-spectrum between two time series is used in meteorology to know their correlation in frequency space. Specially, coespectrum, or real part of cross-spectrum, amplitud and coherence give us many information about the low or high correlation between two variables in a particular frecuency or scale (Stull, 1988). In this work we have investigated cross-spectra of velocity components and temperature measured along the summer 2009 at the CIBA, Research Centre for the Lower Atmosphere, located in Valladolid province (Spain), which is on a quite flat terrain (Cuxart et al., 2000; Viana et al., 2009). In these experimental dataset, among other instrumentation, two sonic anemometers (20 Hz, sampling rate) at 1.5 m and 10 m height are available. Cross-spectra between variables of the two levels, specially, wind vertical component and sonic temperature, under stable stratification are studied in order to improve the knowledge of the proprieties of the momentum and heat fluxes near the ground in the PBL. Nevertheless, power spectral of horizontal components of the wind, at both levels, have been also analysed. The spectra and cross-spectra were performed by mean the Blackman-Tukey method, widely utilised in the time series studies (Blackman & Tukey, 1958) and, where it is

  11. Cross-layer ultrasound video streaming over mobile WiMAX and HSUPA networks.

    PubMed

    Alinejad, Ali; Philip, Nada Y; Istepanian, Robert S H

    2012-01-01

    It is well known that the evolution of 4G-based mobile multimedia network systems will contribute significantly to future mobile healthcare (m-health) applications that require high bandwidth and fast data rates. Central to the success of such emerging applications is the compatibility of broadband networks, such as mobile Worldwide Interoperability For Microwave Access (WiMAX) and High-Speed Uplink Packet Access (HSUPA), and especially their rate adaption issues combined with the acceptable real-time medical quality of service requirements. In this paper, we address the relevant challenges of cross-layer design requirements for real-time rate adaptation of ultrasound video streaming in mobile WiMAX and HSUPA networks. A comparative performance analysis of such approach is validated in two experimental m-health test bed systems for both mobile WiMAX and HSUPA networks. The experimental results have shown an improved performance of mobile WiMAX compared to the HSUPA using the same cross-layer optimization approach. PMID:21571613

  12. Cross-layer ultrasound video streaming over mobile WiMAX and HSUPA networks.

    PubMed

    Alinejad, Ali; Philip, Nada Y; Istepanian, Robert S H

    2012-01-01

    It is well known that the evolution of 4G-based mobile multimedia network systems will contribute significantly to future mobile healthcare (m-health) applications that require high bandwidth and fast data rates. Central to the success of such emerging applications is the compatibility of broadband networks, such as mobile Worldwide Interoperability For Microwave Access (WiMAX) and High-Speed Uplink Packet Access (HSUPA), and especially their rate adaption issues combined with the acceptable real-time medical quality of service requirements. In this paper, we address the relevant challenges of cross-layer design requirements for real-time rate adaptation of ultrasound video streaming in mobile WiMAX and HSUPA networks. A comparative performance analysis of such approach is validated in two experimental m-health test bed systems for both mobile WiMAX and HSUPA networks. The experimental results have shown an improved performance of mobile WiMAX compared to the HSUPA using the same cross-layer optimization approach.

  13. A robust cross-layer metric for routing protocol in mobile wireless ad hoc networks

    NASA Astrophysics Data System (ADS)

    Mucchi, Lorenzo; Chisci, Luigi; Fabbrini, Luca; Giovannetti, Giulio

    2012-12-01

    In a mobile ad-hoc network (MANET) where Mobile Nodes (MNs) self-organize to ensure the communication over radio links, routing protocols clearly play a significant role. In future MANETs, protocols should provide routing under full mobility, power constraints, fast time-varying channels, and nodes subject to high loading. In this article, a novel robust routing protocol, named distributed X-layer fastest path (DXFP), is proposed. The protocol is based on a cross-layer metric which is robust against the time-variations of the network as far as topology (mobility), congestion of the nodes and channel quality (fading, power constraints) are concerned. All these features are integrated in a single physical cost, i.e., the network crossing time, which has to be minimized. Furthermore, several routes from source to destination are stored for a given data flow to efficiently face the disconnections which frequently occur in MANETs. It is shown that the DXFP protocol, though locally operating in a fully distributed way within the MNs, provides, for each data flow, the optimum routes according to the considered metric. The DXFP protocol has been compared with two of the most commonly used routing protocols for MANETs, i.e., dynamic source routing and ad hoc on-demand distance vector, showing significant improvements in performance and robustness.

  14. Cross-layer design for intrusion detection and data security in wireless ad hoc sensor networks

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2007-09-01

    A wireless ad hoc sensor network is a configuration for area surveillance that affords rapid, flexible deployment in arbitrary threat environments. There is no infrastructure support and sensor nodes communicate with each other only when they are in transmission range. The nodes are severely resource-constrained, with limited processing, memory and power capacities and must operate cooperatively to fulfill a common mission in typically unattended modes. In a wireless sensor network (WSN), each sensor at a node can observe locally some underlying physical phenomenon and sends a quantized version of the observation to sink (destination) nodes via wireless links. Since the wireless medium can be easily eavesdropped, links can be compromised by intrusion attacks from nodes that may mount denial-of-service attacks or insert spurious information into routing packets, leading to routing loops, long timeouts, impersonation, and node exhaustion. A cross-layer design based on protocol-layer interactions is proposed for detection and identification of various intrusion attacks on WSN operation. A feature set is formed from selected cross-layer parameters of the WSN protocol to detect and identify security threats due to intrusion attacks. A separate protocol is not constructed from the cross-layer design; instead, security attributes and quantified trust levels at and among nodes established during data exchanges complement customary WSN metrics of energy usage, reliability, route availability, and end-to-end quality-of-service (QoS) provisioning. Statistical pattern recognition algorithms are applied that use observed feature-set patterns observed during network operations, viewed as security audit logs. These algorithms provide the "best" network global performance in the presence of various intrusion attacks. A set of mobile (software) agents distributed at the nodes implement the algorithms, by moving among the layers involved in the network response at each active node

  15. Collision avoidance in TV white spaces: a cross-layer design approach for cognitive radio networks

    NASA Astrophysics Data System (ADS)

    Foukalas, Fotis; Karetsos, George T.

    2015-07-01

    One of the most promising applications of cognitive radio networks (CRNs) is the efficient exploitation of TV white spaces (TVWSs) for enhancing the performance of wireless networks. In this paper, we propose a cross-layer design (CLD) of carrier sense multiple access with collision avoidance (CSMA/CA) mechanism at the medium access control (MAC) layer with spectrum sensing (SpSe) at the physical layer, for identifying the occupancy status of TV bands. The proposed CLD relies on a Markov chain model with a state pair containing both the SpSe and the CSMA/CA from which we derive the collision probability and the achievable throughput. Analytical and simulation results are obtained for different collision avoidance and SpSe implementation scenarios by varying the contention window, back off stage and probability of detection. The obtained results depict the achievable throughput under different collision avoidance and SpSe implementation scenarios indicating thereby the performance of collision avoidance in TVWSs-based CRNs.

  16. Cross-Layer Algorithms for QoS Enhancement in Wireless Multimedia Sensor Networks

    NASA Astrophysics Data System (ADS)

    Saxena, Navrati; Roy, Abhishek; Shin, Jitae

    A lot of emerging applications like advanced telemedicine and surveillance systems, demand sensors to deliver multimedia content with precise level of QoS enhancement. Minimizing energy in sensor networks has been a much explored research area but guaranteeing QoS over sensor networks still remains an open issue. In this letter we propose a cross-layer approach combining Network and MAC layers, for QoS enhancement in wireless multimedia sensor networks. In the network layer a statistical estimate of sensory QoS parameters is performed and a nearoptimal genetic algorithmic solution is proposed to solve the NP-complete QoS-routing problem. On the other hand the objective of the proposed MAC algorithm is to perform the QoS-based packet classification and automatic adaptation of the contention window. Simulation results demonstrate that the proposed protocol is capable of providing lower delay and better throughput, at the cost of reasonable energy consumption, in comparison with other existing sensory QoS protocols.

  17. Constraints of nonresponding flows based on cross layers in the networks

    NASA Astrophysics Data System (ADS)

    Zhou, Zhi-Chao; Xiao, Yang; Wang, Dong

    2016-02-01

    In the active queue management (AQM) scheme, core routers cannot manage and constrain user datagram protocol (UDP) data flows by the sliding window control mechanism in the transport layer due to the nonresponsive nature of such traffic flows. However, the UDP traffics occupy a large part of the network service nowadays which brings a great challenge to the stability of the more and more complex networks. To solve the uncontrollable problem, this paper proposes a cross layers random early detection (CLRED) scheme, which can control the nonresponding UDP-like flows rate effectively when congestion occurs in the access point (AP). The CLRED makes use of the MAC frame acknowledgement (ACK) transmitting congestion information to the sources nodes and utilizes the back-off windows of the MAC layer throttling data rate. Consequently, the UDP-like flows data rate can be restrained timely by the sources nodes in order to alleviate congestion in the complex networks. The proposed CLRED can constrain the nonresponsive flows availably and make the communication expedite, so that the network can sustain stable. The simulation results of network simulator-2 (NS2) verify the proposed CLRED scheme.

  18. A cross-layer duty cycle MAC protocol supporting a pipeline feature for wireless sensor networks.

    PubMed

    Tong, Fei; Xie, Rong; Shu, Lei; Kim, Young-Chon

    2011-01-01

    Although the conventional duty cycle MAC protocols for Wireless Sensor Networks (WSNs) such as RMAC perform well in terms of saving energy and reducing end-to-end delivery latency, they were designed independently and require an extra routing protocol in the network layer to provide path information for the MAC layer. In this paper, we propose a new cross-layer duty cycle MAC protocol with data forwarding supporting a pipeline feature (P-MAC) for WSNs. P-MAC first divides the whole network into many grades around the sink. Each node identifies its grade according to its logical hop distance to the sink and simultaneously establishes a sleep/wakeup schedule using the grade information. Those nodes in the same grade keep the same schedule, which is staggered with the schedule of the nodes in the adjacent grade. Then a variation of the RTS/CTS handshake mechanism is used to forward data continuously in a pipeline fashion from the higher grade to the lower grade nodes and finally to the sink. No extra routing overhead is needed, thus increasing the network scalability while maintaining the superiority of duty-cycling. The simulation results in OPNET show that P-MAC has better performance than S-MAC and RMAC in terms of packet delivery latency and energy efficiency.

  19. A Cross-Layer Duty Cycle MAC Protocol Supporting a Pipeline Feature for Wireless Sensor Networks

    PubMed Central

    Tong, Fei; Xie, Rong; Shu, Lei; Kim, Young-Chon

    2011-01-01

    Although the conventional duty cycle MAC protocols for Wireless Sensor Networks (WSNs) such as RMAC perform well in terms of saving energy and reducing end-to-end delivery latency, they were designed independently and require an extra routing protocol in the network layer to provide path information for the MAC layer. In this paper, we propose a new cross-layer duty cycle MAC protocol with data forwarding supporting a pipeline feature (P-MAC) for WSNs. P-MAC first divides the whole network into many grades around the sink. Each node identifies its grade according to its logical hop distance to the sink and simultaneously establishes a sleep/wakeup schedule using the grade information. Those nodes in the same grade keep the same schedule, which is staggered with the schedule of the nodes in the adjacent grade. Then a variation of the RTS/CTS handshake mechanism is used to forward data continuously in a pipeline fashion from the higher grade to the lower grade nodes and finally to the sink. No extra routing overhead is needed, thus increasing the network scalability while maintaining the superiority of duty-cycling. The simulation results in OPNET show that P-MAC has better performance than S-MAC and RMAC in terms of packet delivery latency and energy efficiency. PMID:22163895

  20. Energy Efficient, Cross-Layer Enabled, Dynamic Aggregation Networks for Next Generation Internet

    NASA Astrophysics Data System (ADS)

    Wang, Michael S.

    Today, the Internet traffic is growing at a near exponential rate, driven predominately by data center-based applications and Internet-of-Things services. This fast-paced growth in Internet traffic calls into question the ability of the existing optical network infrastructure to support this continued growth. The overall optical networking equipment efficiency has not been able to keep up with the traffic growth, creating a energy gap that makes energy and cost expenditures scale linearly with the traffic growth. The implication of this energy gap is that it is infeasible to continue using existing networking equipment to meet the growing bandwidth demand. A redesign of the optical networking platform is needed. The focus of this dissertation is on the design and implementation of energy efficient, cross-layer enabled, dynamic optical networking platforms, which is a promising approach to address the exponentially growing Internet bandwidth demand. Chapter 1 explains the motivation for this work by detailing the huge Internet traffic growth and the unsustainable energy growth of today's networking equipment. Chapter 2 describes the challenges and objectives of enabling agile, dynamic optical networking platforms and the vision of the Center for Integrated Access Networks (CIAN) to realize these objectives; the research objectives of this dissertation and the large body of related work in this field is also summarized. Chapter 3 details the design and implementation of dynamic networking platforms that support wavelength switching granularity. The main contribution of this work involves the experimental validation of deep cross-layer communication across the optical performance monitoring (OPM), data, and control planes. The first experiment shows QoS-aware video streaming over a metro-scale test-bed through optical power monitoring of the transmission wavelength and cross-layer feedback control of the power level. The second experiment extends the performance

  1. Investigation of a hypersonic crossing shock wave/turbulent boundary layer interaction

    NASA Technical Reports Server (NTRS)

    Narayanswami, N; Knight, D. D.; Horstman, C. C.

    1993-01-01

    A combined theoretical and experimental study is presented for the interaction between crossing shock waves generated by (10 deg, 10 deg) sharp fins and a flat plate turbulent boundary layer at Mach 8.3. The theoretical model is the full 3D mean compressible Reynolds-averaged Navier-Stokes (RANS) equations incorporating the algebraic turbulent eddy viscosity model of Baldwin and Lomax (1978). A grid refinement study indicated that adequate resolution of the flow field has been achieved. Computed results agree well with experiment for surface pressure and surface flow patterns and for pitot pressure and yaw angle profiles in the flow field. The computations, however, significantly overpredict surface heat transfer. Analysis of the computed flow field results indicates the formation of complex streamline and wave structures within the interaction region.

  2. Investigation of a hypersonic crossing shock wave/turbulent boundary layer interaction

    NASA Astrophysics Data System (ADS)

    Narayanswami, N.; Knight, D. D.; Horstman, C. C.

    1993-03-01

    A combined theoretical and experimental study is presented for the interaction between crossing shock waves generated by (10°, 10°) sharp fins and a flat plate turbulent boundary layer at Mach 8.3. The theoretical model is the full 3-D mean compressible Reynolds-averaged Navier-Stokes RANS) equations incorporating the algebraic turbulent eddy viscosity model of Baldwin and Lomax. A grid refinement study indicated that adequate resolution of the flowfield has been achieved. Computed results agree well with experiment for surface pressure and surface flow patterns and for pitot pressure and yaw angle profiles in the flowfield. The computations, however, significantly overpredict surface heat transfer. Analysis of the computed flowfield results indicates the formation of complex streamline and wave structures within the interaction region.

  3. Cross-linked hybrid nanofiltration membrane with antibiofouling properties and self-assembled layered morphology.

    PubMed

    Singh, Ajay K; Prakash, S; Kulshrestha, Vaibhav; Shahi, Vinod K

    2012-03-01

    A new siloxane monomer, 3-(3-(diethoxy(2-(5-(4-(10-ethoxy-4-hydroxy-2,2-dimethyl-11-oxa-2-ammonio-6-aza-10-silatridecan-10-yl)phenyl)-1,3,4-oxadi azol-2-ylthio)ethyl)silyl)propylamino)-2-hydroxy-N,N,N-trimethylpropan-1-aminium chloride (OA), was synthesized by reported 3-((4-(5-(2-((3-aminopropyl) diethoxysilyl)ethylthio)-1,3,4-oxadiazol-2-yl)phenyl) diethoxysilyl)propan-1-amine (APDSMO) and glycidyltrimethylammonium chloride (GDTMAC) by epoxide ring-opening reaction. OA-poly(vinyl alcohol) (PVA) hybrid antibiofouling nanofilter (NF) membranes were prepared by acid-catalyzed sol-gel followed by formal cross-linking. Membranes showed wormlike arrangement and self-assembled layered morphology with varying OA content. Hybrid NF membrane, especially OA-6, showed low surface roughness, high hydrophilic nature, low biofouling, high cross-linking density, thermal and mechanical stablility, solvent- and chlorine-tolerant nature, along with good permeability and salt rejection. Prepared OA-6 hybrid NF membrane can be used efficiently for desalting and purification of water with about 2.0 g/L salt content (groundwater in major part of India). The described method provides novel route for producing antibiofouling membranes of diversified applications. PMID:22360398

  4. Influences of an Aluminum Covering Layer on the Performance of Cross-Like Hall Devices.

    PubMed

    Lyu, Fei; Liu, Xinfu; Ding, Yinjie; Toh, Eng-Huat; Zhang, Zhenyan; Pan, Yifan; Wang, Zhen; Li, Chengjie; Li, Li; Sha, Jin; Pan, Hongbing

    2016-01-15

    This work studies the effects of an aluminum covering on the performance of cross-like Hall devices. Four different Hall sensor structures of various sizes were designed and fabricated. The sensitivity and offset of the Hall sensors, two key points impacting their performance, were characterized using a self-built measurement system. The work analyzes the influences of the aluminum covering on those two aspects of the performance. The aluminum layer covering mainly leads to an eddy-current effect in an unstable magnetic field and an additional depletion region above the active region. Those two points have influences on the sensitivity and the offset voltage, respectively. The analysis guides the designer whether to choose covering with an aluminum layer the active region of the Hall sensor as a method to reduce the flicker noise and to improve the stability of the Hall sensor. Because Hall devices, as a reference element, always suffer from a large dispersion, improving their stability is a crucial issue.

  5. Cross-layer protocol design for QoS optimization in real-time wireless sensor networks

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2010-04-01

    The metrics of quality of service (QoS) for each sensor type in a wireless sensor network can be associated with metrics for multimedia that describe the quality of fused information, e.g., throughput, delay, jitter, packet error rate, information correlation, etc. These QoS metrics are typically set at the highest, or application, layer of the protocol stack to ensure that performance requirements for each type of sensor data are satisfied. Application-layer metrics, in turn, depend on the support of the lower protocol layers: session, transport, network, data link (MAC), and physical. The dependencies of the QoS metrics on the performance of the higher layers of the Open System Interconnection (OSI) reference model of the WSN protocol, together with that of the lower three layers, are the basis for a comprehensive approach to QoS optimization for multiple sensor types in a general WSN model. The cross-layer design accounts for the distributed power consumption along energy-constrained routes and their constituent nodes. Following the author's previous work, the cross-layer interactions in the WSN protocol are represented by a set of concatenated protocol parameters and enabling resource levels. The "best" cross-layer designs to achieve optimal QoS are established by applying the general theory of martingale representations to the parameterized multivariate point processes (MVPPs) for discrete random events occurring in the WSN. Adaptive control of network behavior through the cross-layer design is realized through the parametric factorization of the stochastic conditional rates of the MVPPs. The cross-layer protocol parameters for optimal QoS are determined in terms of solutions to stochastic dynamic programming conditions derived from models of transient flows for heterogeneous sensor data and aggregate information over a finite time horizon. Markov state processes, embedded within the complex combinatorial history of WSN events, are more computationally

  6. Molecular-scale dynamics of light-induced spin cross-over in a two-dimensional layer.

    PubMed

    Bairagi, Kaushik; Iasco, Olga; Bellec, Amandine; Kartsev, Alexey; Li, Dongzhe; Lagoute, Jérôme; Chacon, Cyril; Girard, Yann; Rousset, Sylvie; Miserque, Frédéric; Dappe, Yannick J; Smogunov, Alexander; Barreteau, Cyrille; Boillot, Marie-Laure; Mallah, Talal; Repain, Vincent

    2016-01-01

    Spin cross-over molecules show the unique ability to switch between two spin states when submitted to external stimuli such as temperature, light or voltage. If controlled at the molecular scale, such switches would be of great interest for the development of genuine molecular devices in spintronics, sensing and for nanomechanics. Unfortunately, up to now, little is known on the behaviour of spin cross-over molecules organized in two dimensions and their ability to show cooperative transformation. Here we demonstrate that a combination of scanning tunnelling microscopy measurements and ab initio calculations allows discriminating unambiguously between both states by local vibrational spectroscopy. We also show that a single layer of spin cross-over molecules in contact with a metallic surface displays light-induced collective processes between two ordered mixed spin-state phases with two distinct timescale dynamics. These results open a way to molecular scale control of two-dimensional spin cross-over layers. PMID:27425776

  7. Molecular-scale dynamics of light-induced spin cross-over in a two-dimensional layer

    NASA Astrophysics Data System (ADS)

    Bairagi, Kaushik; Iasco, Olga; Bellec, Amandine; Kartsev, Alexey; Li, Dongzhe; Lagoute, Jérôme; Chacon, Cyril; Girard, Yann; Rousset, Sylvie; Miserque, Frédéric; Dappe, Yannick J.; Smogunov, Alexander; Barreteau, Cyrille; Boillot, Marie-Laure; Mallah, Talal; Repain, Vincent

    2016-07-01

    Spin cross-over molecules show the unique ability to switch between two spin states when submitted to external stimuli such as temperature, light or voltage. If controlled at the molecular scale, such switches would be of great interest for the development of genuine molecular devices in spintronics, sensing and for nanomechanics. Unfortunately, up to now, little is known on the behaviour of spin cross-over molecules organized in two dimensions and their ability to show cooperative transformation. Here we demonstrate that a combination of scanning tunnelling microscopy measurements and ab initio calculations allows discriminating unambiguously between both states by local vibrational spectroscopy. We also show that a single layer of spin cross-over molecules in contact with a metallic surface displays light-induced collective processes between two ordered mixed spin-state phases with two distinct timescale dynamics. These results open a way to molecular scale control of two-dimensional spin cross-over layers.

  8. Molecular-scale dynamics of light-induced spin cross-over in a two-dimensional layer

    PubMed Central

    Bairagi, Kaushik; Iasco, Olga; Bellec, Amandine; Kartsev, Alexey; Li, Dongzhe; Lagoute, Jérôme; Chacon, Cyril; Girard, Yann; Rousset, Sylvie; Miserque, Frédéric; Dappe, Yannick J; Smogunov, Alexander; Barreteau, Cyrille; Boillot, Marie-Laure; Mallah, Talal; Repain, Vincent

    2016-01-01

    Spin cross-over molecules show the unique ability to switch between two spin states when submitted to external stimuli such as temperature, light or voltage. If controlled at the molecular scale, such switches would be of great interest for the development of genuine molecular devices in spintronics, sensing and for nanomechanics. Unfortunately, up to now, little is known on the behaviour of spin cross-over molecules organized in two dimensions and their ability to show cooperative transformation. Here we demonstrate that a combination of scanning tunnelling microscopy measurements and ab initio calculations allows discriminating unambiguously between both states by local vibrational spectroscopy. We also show that a single layer of spin cross-over molecules in contact with a metallic surface displays light-induced collective processes between two ordered mixed spin-state phases with two distinct timescale dynamics. These results open a way to molecular scale control of two-dimensional spin cross-over layers. PMID:27425776

  9. Cross-diffusion-driven hydrodynamic instabilities in a double-layer system: General classification and nonlinear simulations.

    PubMed

    Budroni, M A

    2015-12-01

    Cross diffusion, whereby a flux of a given species entrains the diffusive transport of another species, can trigger buoyancy-driven hydrodynamic instabilities at the interface of initially stable stratifications. Starting from a simple three-component case, we introduce a theoretical framework to classify cross-diffusion-induced hydrodynamic phenomena in two-layer stratifications under the action of the gravitational field. A cross-diffusion-convection (CDC) model is derived by coupling the fickian diffusion formalism to Stokes equations. In order to isolate the effect of cross-diffusion in the convective destabilization of a double-layer system, we impose a starting concentration jump of one species in the bottom layer while the other one is homogeneously distributed over the spatial domain. This initial configuration avoids the concurrence of classic Rayleigh-Taylor or differential-diffusion convective instabilities, and it also allows us to activate selectively the cross-diffusion feedback by which the heterogeneously distributed species influences the diffusive transport of the other species. We identify two types of hydrodynamic modes [the negative cross-diffusion-driven convection (NCC) and the positive cross-diffusion-driven convection (PCC)], corresponding to the sign of this operational cross-diffusion term. By studying the space-time density profiles along the gravitational axis we obtain analytical conditions for the onset of convection in terms of two important parameters only: the operational cross-diffusivity and the buoyancy ratio, giving the relative contribution of the two species to the global density. The general classification of the NCC and PCC scenarios in such parameter space is supported by numerical simulations of the fully nonlinear CDC problem. The resulting convective patterns compare favorably with recent experimental results found in microemulsion systems. PMID:26764804

  10. Cross-diffusion-driven hydrodynamic instabilities in a double-layer system: General classification and nonlinear simulations

    NASA Astrophysics Data System (ADS)

    Budroni, M. A.

    2015-12-01

    Cross diffusion, whereby a flux of a given species entrains the diffusive transport of another species, can trigger buoyancy-driven hydrodynamic instabilities at the interface of initially stable stratifications. Starting from a simple three-component case, we introduce a theoretical framework to classify cross-diffusion-induced hydrodynamic phenomena in two-layer stratifications under the action of the gravitational field. A cross-diffusion-convection (CDC) model is derived by coupling the fickian diffusion formalism to Stokes equations. In order to isolate the effect of cross-diffusion in the convective destabilization of a double-layer system, we impose a starting concentration jump of one species in the bottom layer while the other one is homogeneously distributed over the spatial domain. This initial configuration avoids the concurrence of classic Rayleigh-Taylor or differential-diffusion convective instabilities, and it also allows us to activate selectively the cross-diffusion feedback by which the heterogeneously distributed species influences the diffusive transport of the other species. We identify two types of hydrodynamic modes [the negative cross-diffusion-driven convection (NCC) and the positive cross-diffusion-driven convection (PCC)], corresponding to the sign of this operational cross-diffusion term. By studying the space-time density profiles along the gravitational axis we obtain analytical conditions for the onset of convection in terms of two important parameters only: the operational cross-diffusivity and the buoyancy ratio, giving the relative contribution of the two species to the global density. The general classification of the NCC and PCC scenarios in such parameter space is supported by numerical simulations of the fully nonlinear CDC problem. The resulting convective patterns compare favorably with recent experimental results found in microemulsion systems.

  11. Cross-scale modelling of transpiration from stomata via the leaf boundary layer

    PubMed Central

    Defraeye, Thijs; Derome, Dominique; Verboven, Pieter; Carmeliet, Jan; Nicolai, Bart

    2014-01-01

    Background and Aims Leaf transpiration is a key parameter for understanding land surface–climate interactions, plant stress and plant structure–function relationships. Transpiration takes place at the microscale level, namely via stomata that are distributed discretely over the leaf surface with a very low surface coverage (approx. 0·2–5 %). The present study aims to shed more light on the dependency of the leaf boundary-layer conductance (BLC) on stomatal surface coverage and air speed. Methods An innovative three-dimensional cross-scale modelling approach was applied to investigate convective mass transport from leaves, using computational fluid dynamics. The gap between stomatal and leaf scale was bridged by including all these scales in the same computational model (10−5–10−1 m), which implies explicitly modelling individual stomata. Key Results BLC was strongly dependent on stomatal surface coverage and air speed. Leaf BLC at low surface coverage ratios (CR), typical for stomata, was still relatively high, compared with BLC of a fully wet leaf (hypothetical CR of 100 %). Nevertheless, these conventional BLCs (CR of 100 %), as obtained from experiments or simulations on leaf models, were found to overpredict the convective exchange. In addition, small variations in stomatal CR were found to result in large variations in BLCs. Furthermore, stomata of a certain size exhibited a higher mass transfer rate at lower CRs. Conclusions The proposed cross-scale modelling approach allows us to increase our understanding of transpiration at the sub-leaf level as well as the boundary-layer microclimate in a way currently not feasible experimentally. The influence of stomatal size, aperture and surface density, and also flow-field parameters can be studied using the model, and prospects for further improvement of the model are presented. An important conclusion of the study is that existing measures of conductances (e.g. from artificial leaves) can be

  12. Suppression of Cross Contamination in Multi-Layer Thin Film Prepared by Using Rotating Hexagonal Sputtering Cathode.

    PubMed

    Park, Se Yeon; Choi, Bum Ho; Lee, Jong Ho

    2015-01-01

    In this study, single- and multi-layered thin films were prepared on a glass substrate using a newly developed rotating hexagonal sputtering cathode in a single chamber. The rotatinghexagonal sputtering cathode can install up to six different sputtering targets or six single targets in a cathode. Using the rotating hexagonal cathode, we prepared a single-layered AZO film and a multi-layer film to evaluate the performance of hexagonal gun. Cross-contamination, which is often observed in multi-layer thin film preparation, was suppressed to nearly zero by controlling process parameters and revising hardware. Energy-saving effects of five-layered glass were also verified by measuring the temperature.

  13. Viscoelastic properties of adsorbed and cross-linked polypeptide and protein layers at a solid-liquid interface.

    PubMed

    Dutta, Amit K; Nayak, Arpan; Belfort, Georges

    2008-08-01

    The real-time changes in viscoelasticity of adsorbed poly(L-lysine) (PLL) and adsorbed histone (lysine rich fraction) due to cross-linking by glutaraldehyde and corresponding release of associated water were investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D) and attenuated total reflection Fourier transform infrared spectroscopy (ATR/FTIR). The kinetics of PLL and histone adsorption were measured through changes in mass adsorbed onto a gold-coated quartz surface from changes in frequency and dissipation and using the Voigt viscoelastic model. Prior to cross-linking, the shear viscosity and shear modulus of the adsorbed PLL layer were approximately 3.0 x 10(-3) Pas and approximately 2.5 x 10(5) Pa, respectively, while after cross-linking, they increased to approximately 17.5 x 10(-3) Pas and approximately 2.5 x 10(6) Pa, respectively. For the adsorbed histone layer, shear viscosity and shear modulus increased modestly from approximately 1.3 x 10(-3) to approximately 2.0 x 10(-3) Pas and from approximately 1.2 x 10(4) to approximately 1.6 x 10(4) Pa, respectively. The adsorbed mass estimated from the Sauerbrey equation (perfectly elastic) and the Voigt viscoelastic model differ appreciably prior to cross-linking whereas after cross-linking they converged. This is because trapped water molecules were released during cross-linking. This was confirmed experimentally via ATR/FTIR measurements. The variation in viscoelastic properties increased substantially after cross-linking presumably due to fluctuation of the randomly cross-linked network structure. An increase in fluctuation of the viscoelastic properties and the loss of imbibed water could be used as a signature of the formation of a cross-linked network and the amount of cross-linking, respectively. PMID:18508070

  14. Combined bio-inspired/evolutionary computational methods in cross-layer protocol optimization for wireless ad hoc sensor networks

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2011-06-01

    Published studies have focused on the application of one bio-inspired or evolutionary computational method to the functions of a single protocol layer in a wireless ad hoc sensor network (WSN). For example, swarm intelligence in the form of ant colony optimization (ACO), has been repeatedly considered for the routing of data/information among nodes, a network-layer function, while genetic algorithms (GAs) have been used to select transmission frequencies and power levels, physical-layer functions. Similarly, artificial immune systems (AISs) as well as trust models of quantized data reputation have been invoked for detection of network intrusions that cause anomalies in data and information; these act on the application and presentation layers. Most recently, a self-organizing scheduling scheme inspired by frog-calling behavior for reliable data transmission in wireless sensor networks, termed anti-phase synchronization, has been applied to realize collision-free transmissions between neighboring nodes, a function of the MAC layer. In a novel departure from previous work, the cross-layer approach to WSN protocol design suggests applying more than one evolutionary computational method to the functions of the appropriate layers to improve the QoS performance of the cross-layer design beyond that of one method applied to a single layer's functions. A baseline WSN protocol design, embedding GAs, anti-phase synchronization, ACO, and a trust model based on quantized data reputation at the physical, MAC, network, and application layers, respectively, is constructed. Simulation results demonstrate the synergies among the bioinspired/ evolutionary methods of the proposed baseline design improve the overall QoS performance of networks over that of a single computational method.

  15. Laser interferometer skin-friction measurements of crossing-shock-wave/turbulent-boundary-layer interactions

    NASA Technical Reports Server (NTRS)

    Garrison, T. J.; Settles, G. S.; Narayanswami, N.; Knight, D. D.

    1994-01-01

    Wall shear stress measurements beneath crossing-shock-wave/turbulent boundary-layer interactions have been made for three interactions of different strengths. The interactions are generated by two sharp fins at symetric angles of attack mounted on a flat plate. The shear stress measurements were made for fin angles of 7 and 11 deg at Mach 3 and 15 deg at Mach 3.85. The measurements were made using a laser interferometer skin-friction meter, a device that determines the wall shear by optically measuring the time rate of thinning of an oil film placed on the test model surface. Results of the measurements reveal high skin-friction coefficients in the vicinity of the fin/plate junction and the presence of quasi-two-dimensional flow separation on the interaction center line. Additionally, two Navier-Stokes computations, one using a Baldwin-Lomax turbulence model and one using a k-epsilon model, are compared with the experimental results for the Mach 3.85, 15-deg interaction case. Although the k-epsilon model did a reasonable job of predicting the overall trend in portions of the skin-friction distribution, neither computation fully captured the physics of the near-surface flow in this complex interaction.

  16. The effect of varying Mach number on crossing, glancing shocks/turbulent boundary-layer interactions

    NASA Technical Reports Server (NTRS)

    Hingst, W. R.; Williams, K. E.

    1991-01-01

    Two crossing side-wall shocks interacting with a supersonic tunnel wall boundary layer have been investigated over a Mach number range of 2.5 to 4.0. The investigation included a range of equal shock strengths produced by shock generators at angles from 4.0 to 12.0 degrees. Results of flow visualization show that the interaction is unseparated at the low shock generator angles. With increasing shock strength, the flow begins to form a separated region that grows in size and moves forward and eventually the model unstarts. The wall static pressures show a symmetrical compression that merges on the centerline upstream of the inviscid shock locations and becomes more 1D downstream. The region of the 1D pressure gradient moves upstream with increasing shock strengths until it coincides with the leading edge of the shock generators at the limit before model unstart. At the limiting conditions the wall pressure gradients are primarily in the axial direction throughout.

  17. Parametric investigation on mixing in a micromixer with two-layer crossing channels.

    PubMed

    Hossain, Shakhawat; Kim, Kwang-Yong

    2016-01-01

    This work presents a parametric investigation on flow and mixing in a chaotic micromixer consisting of two-layer crossing channels proposed by Xia et al. (Lab Chip 5: 748-755, 2005). The flow and mixing performance were numerically analyzed using commercially available software ANSYS CFX-15.0, which solves the Navier-Stokes and mass conservation equations with a diffusion-convection model in a Reynolds number range from 0.2 to 40. A mixing index based on the variance of the mass fraction of the mixture was employed to evaluate the mixing performance of the micromixer. The flow structure in the channel was also investigated to identify the relationship with mixing performance. The mixing performance and pressure-drop were evaluated with two dimensionless geometric parameters, i.e., ratios of the sub-channel width to the main channel width and the channels depth to the main channel width. The results revealed that the mixing index at the exit of the micromixer increases with increase in the channel depth-to-width ratio, but decreases with increase in the sub-channel width to main channel width ratio. And, it was found that the mixing index could be increased up to 0.90 with variations of the geometric parameters at Re = 0.2, and the pressure drop was very sensitive to the geometric parameters. PMID:27390635

  18. Cross-sectional observation of nanostructured catalyst layer of polymer electrolyte fuel cell using FIB/SEM

    NASA Astrophysics Data System (ADS)

    Katayanagi, Yuta; Shimizu, Takahiro; Hashimasa, Yoshiyuki; Matsushita, Nobuhiro; Yamazaki, Yohtaro; Yamaguchi, Takeo

    2015-04-01

    The catalyst layer structure of a membrane electrode assembly (MEA) affects fuel cell performance. Cross-sectional observation is the most simple and effective way to evaluate the catalyst layer structure. Although focused ion beam (FIB) is a common tool for cross-sectional observation, sputtering of the ion beam causes heat damage to the MEA sample, which in previous studies was mitigated by sample cooling using liquid nitrogen. In this study, the sample holder and FIB stage were newly developed for cross-sectional observation of MEA catalyst layers, which suppressed heat damage by thermoelectric cooling using Peltier elements. Two types of degradation mode tests, load cycle and startup-shutdown cycle, were conducted on the MEA sample and their cross-sectional observations were performed using newly developed scanning electron microscope stages, which can mount the sample holder directly. The growth of platinum nanoparticles corresponding to the degradation of the active surface area was clearly observed for the sample subjected to the load cycle test. On the other hand, the corrosion of carbon particles was observed for the startup-shutdown sample. Since the cross-sectional samples were fabricated without heat damage by FIB with the newly developed stage, the difference in microstructure for these modes could be clearly distinguished.

  19. Cross-layer protocols optimized for real-time multimedia services in energy-constrained mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2003-07-01

    Mobile ad hoc networking (MANET) supports self-organizing, mobile infrastructures and enables an autonomous network of mobile nodes that can operate without a wired backbone. Ad hoc networks are characterized by multihop, wireless connectivity via packet radios and by the need for efficient dynamic protocols. All routers are mobile and can establish connectivity with other nodes only when they are within transmission range. Importantly, ad hoc wireless nodes are resource-constrained, having limited processing, memory, and battery capacity. Delivery of high quality-ofservice (QoS), real-time multimedia services from Internet-based applications over a MANET is a challenge not yet achieved by proposed Internet Engineering Task Force (IETF) ad hoc network protocols in terms of standard performance metrics such as end-to-end throughput, packet error rate, and delay. In the distributed operations of route discovery and maintenance, strong interaction occurs across MANET protocol layers, in particular, the physical, media access control (MAC), network, and application layers. The QoS requirements are specified for the service classes by the application layer. The cross-layer design must also satisfy the battery-limited energy constraints, by minimizing the distributed power consumption at the nodes and of selected routes. Interactions across the layers are modeled in terms of the set of concatenated design parameters including associated energy costs. Functional dependencies of the QoS metrics are described in terms of the concatenated control parameters. New cross-layer designs are sought that optimize layer interdependencies to achieve the "best" QoS available in an energy-constrained, time-varying network. The protocol design, based on a reactive MANET protocol, adapts the provisioned QoS to dynamic network conditions and residual energy capacities. The cross-layer optimization is based on stochastic dynamic programming conditions derived from time-dependent models of

  20. Wall paintings studied using Raman spectroscopy: a comparative study between various assays of cross sections and external layers.

    PubMed

    Perez-Rodriguez, Jose Luis; Robador, Maria Dolores; Centeno, Miguel Angel; Siguenza, Belinda; Duran, Adrian

    2014-01-01

    This work describes a comparative study between in situ applications of portable Raman spectroscopy and direct laboratory measurements using micro-Raman spectroscopy on the surface of small samples and of cross sections. The study was performed using wall paintings from different sites of the Alcazar of Seville. Little information was obtained using a portable Raman spectrometer due to the presence of an acrylic polymer, calcium oxalate, calcite and gypsum that was formed or deposited on the surface. The pigments responsible for different colours, except cinnabar, were not detected by the micro-Raman spectroscopy study of the surface of small samples taken from the wall paintings due to the presence of surface contaminants. The pigments and plaster were characterised using cross sections. The black colour consisted of carbon black. The red layers were formed by cinnabar and white lead or by iron oxides. The green and white colours were composed of green emerald or atacamite and calcite, respectively. Pb3O4 has also been characterised. The white layers (plaster) located under the colour layers consisted of calcite, quartz and feldspars. The fresco technique was used to create the wall paintings. A wall painting located on a gypsum layer was also studied. The Naples yellow in this wall painting was not characterised due to the presence of glue and oils. This study showed the advantage of studying cross sections to completely characterise the pigments and plaster in the studied wall paintings. PMID:24216251

  1. Wall paintings studied using Raman spectroscopy: a comparative study between various assays of cross sections and external layers.

    PubMed

    Perez-Rodriguez, Jose Luis; Robador, Maria Dolores; Centeno, Miguel Angel; Siguenza, Belinda; Duran, Adrian

    2014-01-01

    This work describes a comparative study between in situ applications of portable Raman spectroscopy and direct laboratory measurements using micro-Raman spectroscopy on the surface of small samples and of cross sections. The study was performed using wall paintings from different sites of the Alcazar of Seville. Little information was obtained using a portable Raman spectrometer due to the presence of an acrylic polymer, calcium oxalate, calcite and gypsum that was formed or deposited on the surface. The pigments responsible for different colours, except cinnabar, were not detected by the micro-Raman spectroscopy study of the surface of small samples taken from the wall paintings due to the presence of surface contaminants. The pigments and plaster were characterised using cross sections. The black colour consisted of carbon black. The red layers were formed by cinnabar and white lead or by iron oxides. The green and white colours were composed of green emerald or atacamite and calcite, respectively. Pb3O4 has also been characterised. The white layers (plaster) located under the colour layers consisted of calcite, quartz and feldspars. The fresco technique was used to create the wall paintings. A wall painting located on a gypsum layer was also studied. The Naples yellow in this wall painting was not characterised due to the presence of glue and oils. This study showed the advantage of studying cross sections to completely characterise the pigments and plaster in the studied wall paintings.

  2. Cross-layer cluster-based energy-efficient protocol for wireless sensor networks.

    PubMed

    Mammu, Aboobeker Sidhik Koyamparambil; Hernandez-Jayo, Unai; Sainz, Nekane; de la Iglesia, Idoia

    2015-01-01

    Recent developments in electronics and wireless communications have enabled the improvement of low-power and low-cost wireless sensors networks (WSNs). One of the most important challenges in WSNs is to increase the network lifetime due to the limited energy capacity of the network nodes. Another major challenge in WSNs is the hot spots that emerge as locations under heavy traffic load. Nodes in such areas quickly drain energy resources, leading to disconnection in network services. In such an environment, cross-layer cluster-based energy-efficient algorithms (CCBE) can prolong the network lifetime and energy efficiency. CCBE is based on clustering the nodes to different hexagonal structures. A hexagonal cluster consists of cluster members (CMs) and a cluster head (CH). The CHs are selected from the CMs based on nodes near the optimal CH distance and the residual energy of the nodes. Additionally, the optimal CH distance that links to optimal energy consumption is derived. To balance the energy consumption and the traffic load in the network, the CHs are rotated among all CMs. In WSNs, energy is mostly consumed during transmission and reception. Transmission collisions can further decrease the energy efficiency. These collisions can be avoided by using a contention-free protocol during the transmission period. Additionally, the CH allocates slots to the CMs based on their residual energy to increase sleep time. Furthermore, the energy consumption of CH can be further reduced by data aggregation. In this paper, we propose a data aggregation level based on the residual energy of CH and a cost-aware decision scheme for the fusion of data. Performance results show that the CCBE scheme performs better in terms of network lifetime, energy consumption and throughput compared to low-energy adaptive clustering hierarchy (LEACH) and hybrid energy-efficient distributed clustering (HEED).

  3. Cross-Layer Cluster-Based Energy-Efficient Protocol for Wireless Sensor Networks

    PubMed Central

    Mammu, Aboobeker Sidhik Koyamparambil; Hernandez-Jayo, Unai; Sainz, Nekane; de la Iglesia, Idoia

    2015-01-01

    Recent developments in electronics and wireless communications have enabled the improvement of low-power and low-cost wireless sensors networks (WSNs). One of the most important challenges in WSNs is to increase the network lifetime due to the limited energy capacity of the network nodes. Another major challenge in WSNs is the hot spots that emerge as locations under heavy traffic load. Nodes in such areas quickly drain energy resources, leading to disconnection in network services. In such an environment, cross-layer cluster-based energy-efficient algorithms (CCBE) can prolong the network lifetime and energy efficiency. CCBE is based on clustering the nodes to different hexagonal structures. A hexagonal cluster consists of cluster members (CMs) and a cluster head (CH). The CHs are selected from the CMs based on nodes near the optimal CH distance and the residual energy of the nodes. Additionally, the optimal CH distance that links to optimal energy consumption is derived. To balance the energy consumption and the traffic load in the network, the CHs are rotated among all CMs. In WSNs, energy is mostly consumed during transmission and reception. Transmission collisions can further decrease the energy efficiency. These collisions can be avoided by using a contention-free protocol during the transmission period. Additionally, the CH allocates slots to the CMs based on their residual energy to increase sleep time. Furthermore, the energy consumption of CH can be further reduced by data aggregation. In this paper, we propose a data aggregation level based on the residual energy of CH and a cost-aware decision scheme for the fusion of data. Performance results show that the CCBE scheme performs better in terms of network lifetime, energy consumption and throughput compared to low-energy adaptive clustering hierarchy (LEACH) and hybrid energy-efficient distributed clustering (HEED). PMID:25860073

  4. Analytic expressions for atomic layer deposition: Coverage, throughput, and materials utilization in cross-flow, particle coating, and spatial atomic layer deposition

    SciTech Connect

    Yanguas-Gil, Angel; Elam, Jeffrey W.

    2014-05-15

    In this work, the authors present analytic models for atomic layer deposition (ALD) in three common experimental configurations: cross-flow, particle coating, and spatial ALD. These models, based on the plug-flow and well-mixed approximations, allow us to determine the minimum dose times and materials utilization for all three configurations. A comparison between the three models shows that throughput and precursor utilization can each be expressed by universal equations, in which the particularity of the experimental system is contained in a single parameter related to the residence time of the precursor in the reactor. For the case of cross-flow reactors, the authors show how simple analytic expressions for the reactor saturation profiles agree well with experimental results. Consequently, the analytic model can be used to extract information about the ALD surface chemistry (e.g., the reaction probability) by comparing the analytic and experimental saturation profiles, providing a useful tool for characterizing new and existing ALD processes.

  5. Imaging high contrast layers within a gravel aquifer using full-waveform cross-hole GPR inversion

    NASA Astrophysics Data System (ADS)

    Klotzsche, A.; Van Der Kruk, J.; Vereecken, H.

    2011-12-01

    Cross-hole ground penetrating radar (GPR) is widely used in geological, hydrological and engineering investigations to map the distribution of dielectric permittivity and electrical conductivity. These electromagnetic parameters are closely linked to hydrogeological parameters. Traditionally, ray-based methods are used to invert cross-hole GPR data using first arrival travel times and first cycle amplitudes and only a fraction of the information contained in the radar data is used such that the resolution of conventional standard ray-based inversion schemes is limited. For example, late arrivals that have large amplitudes can be completely ignored by the ray-based techniques. On the other hand, the full-waveform inversion considers the entire waveform and can therefore significantly improve imaging results of cross-hole GPR data. Especially, for improved characterisation of preferential flow paths, high resolution images of the aquifer are necessary. We recently inverted cross-hole GPR data measured in the saturated zone of a gravel aquifer (4m - 10m depth) in the Thur valley, Switzerland using the full-waveform inversion. Here, we demonstrate that the full-waveform inversion is able to identify high contrast waveguide layers between two boreholes using cross-hole GPR measurements. Our full-waveform inversion returns high-resolution images throughout the model domain including the upper part of the aquifer which contains a high permittivity layer between 5m - 6m depth. A detailed analysis for sources and receivers that were present at the depth of the high permittivity layer shows high amplitudes for late arrivals of the measured data forming elongated wave trains that are consistent with the presence of a low velocity waveguide. These wave trains are formed due to total internal reflections beyond the critical angle within this layer which results in a trapping of most of the energy. The same characteristics have been observed for dispersive surface GPR data

  6. On the Nonlinear Evolution of a Stationary Cross-Flow Vortex in a Fully Three-Dimensional Boundary Layer Flow

    NASA Technical Reports Server (NTRS)

    Gajjar, J. S. B.

    1995-01-01

    We consider the nonlinear stability of a fully three-dimensional boundary layer flow in an incompressible fluid and derive an equation governing the nonlinear development of a stationary cross-flow vortex. The amplitude equation is a novel integro-differential equation which has spatial derivatives of the amplitude occurring in the kernal function. It is shown that the evolution of the cross-flow vortex is strongly coupled to the properties of an unsteady wall layer which is in fact driven by an unknown slip velocity, proportional to the amplitude of the cross-flow vortex. The work is extended to obtain the corresponding equation for rotating disk flow. A number of special cases are examined and the numerical solution for one of cases, and further analysis, demonstrates the existence of finite-distance as well as focussing type singularities. The numerical solutions also indicate the presence of a new type of nonlinear wave solution for a certain set of parameter values.

  7. Streaming potential for microchannels of arbitrary cross-sectional shapes for thin electric double layers.

    PubMed

    Park, H M; Lim, J Y

    2009-08-15

    The streaming potential of electrokinetic flows in microchannels affects flow rate and is usually exploited to determine the zeta potential of microchannels. In the present investigation, we derive a semianalytic formula for the streaming potential of microchannels with arbitrary cross-sectional shapes valid for high zeta potentials as well as reasonably low zeta potentials. This formula satisfies the Onsager reciprocity principle at the limit of low zeta potential where the Debye-Hückel approximation is valid. The simple semianalytic formula for the streaming potential derived in the present work can be employed to investigate electrokinetic flows and determine the zeta potentials of microchannels with arbitrary cross-sectional shapes. PMID:19464020

  8. Surface and flow field measurements in a symmetric crossing shock wave/turbulent boundary-layer interaction

    NASA Technical Reports Server (NTRS)

    Davis, D. O.; Hingst, W. R.

    1992-01-01

    Results of an experimental investigation of a symmetric crossing shock/turbulent boundary layer interaction are presented for a Mach number of 3.44 and deflection angles of 2, 6, 8, and 9 degrees. The interaction strengths vary from weak to strong enough to cause a large region of separated flow. Measured quantities include surface static pressure (both steady and unsteady) and flowfield Pitot pressures. Pitot profiles in the plane of symmetry through the interaction region are shown for various deflection angles. Oil flow visualization and the results of a trace gas streamline tracking technique are also presented.

  9. Interaction of two glancing, crossing shock waves with a turbulent boundary-layer at various Mach numbers

    NASA Technical Reports Server (NTRS)

    Hingst, Warren R.; Williams, Kevin E.

    1991-01-01

    A preliminary experimental investigation was conducted to study two crossing, glancing shock waves of equal strengths, interacting with the boundary-layer developed on a supersonic wind tunnel wall. This study was performed at several Mach numbers between 2.5 and 4.0. The shock waves were created by fins (shock generators), spanning the tunnel test section, that were set at angles varying from 4 to 12 degrees. The data acquired are wall static pressure measurements, and qualitative information in the form of oil flow and schlieren visualizations. The principle aim is two-fold. First, a fundamental understanding of the physics underlying this flow phenomena is desired. Also, a comprehensive data set is needed for computational fluid dynamic code validation. Results indicate that for small shock generator angles, the boundary-layer remains attached throughout the flow field. However, with increasing shock strengths (increasing generator angles), boundary layer separation does occur and becomes progressively more severe as the generator angles are increased further. The location of the separation, which starts well downstream of the shock crossing point, moves upstream as shock strengths are increased. At the highest generator angles, the separation appears to begin coincident with the generator leading edges and engulfs most of the area between the generators. This phenomena occurs very near the 'unstart' limit for the generators. The wall pressures at the lower generator angles are nominally consistent with the flow geometries (i.e. shock patterns) although significantly affected by the boundary-layer upstream influence. As separation occurs, the wall pressures exhibit a gradient that is mainly axial in direction in the vicinity of the separation. At the limiting conditions the wall pressure gradients are primarily in the axial direction throughout.

  10. Layers

    NASA Astrophysics Data System (ADS)

    Hong, K. J.; Jeong, T. S.; Youn, C. J.

    2014-09-01

    The temperature-dependent photoresponse characteristics of MnAl2S4 layers have been investigated, for the first time, by use of photocurrent (PC) spectroscopy. Three peaks were observed at all temperatures. The electronic origin of these peaks was associated with band-to-band transitions from the valence-band states Γ4( z), Γ5( x), and Γ5( y) to the conduction-band state Γ1( s). On the basis of the relationship between PC-peak energy and temperature, the optical band gap could be well expressed by the expression E g( T) = E g(0) - 2.80 × 10-4 T 2/(287 + T), where E g(0) was estimated to be 3.7920 eV, 3.7955 eV, and 3.8354 eV for the valence-band states Γ4( z), Γ5( x), and Γ5( y), respectively. Results from PC spectroscopy revealed the crystal-field and spin-orbit splitting were 3.5 meV and 39.9 meV. The gradual decrease of PC intensity with decreasing temperature can be explained on the basis of trapping centers associated with native defects in the MnAl2S4 layers. Plots of log J ph, the PC current density, against 1/ T, revealed a dominant trap level in the high-temperature region. By comparing PC and the Hall effect results, we confirmed that this trap level is a shallow donor 18.9 meV below the conduction band.

  11. An MILP-Based Cross-Layer Optimization for a Multi-Reader Arbitration in the UHF RFID System

    PubMed Central

    Choi, Jinchul; Lee, Chaewoo

    2011-01-01

    In RFID systems, the performance of each reader such as interrogation range and tag recognition rate may suffer from interferences from other readers. Since the reader interference can be mitigated by output signal power control, spectral and/or temporal separation among readers, the system performance depends on how to adapt the various reader arbitration metrics such as time, frequency, and output power to the system environment. However, complexity and difficulty of the optimization problem increase with respect to the variety of the arbitration metrics. Thus, most proposals in previous study have been suggested to primarily prevent the reader collision with consideration of one or two arbitration metrics. In this paper, we propose a novel cross-layer optimization design based on the concept of combining time division, frequency division, and power control not only to solve the reader interference problem, but also to achieve the multiple objectives such as minimum interrogation delay, maximum reader utilization, and energy efficiency. Based on the priority of the multiple objectives, our cross-layer design optimizes the system sequentially by means of the mixed-integer linear programming. In spite of the multi-stage optimization, the optimization design is formulated as a concise single mathematical form by properly assigning a weight to each objective. Numerical results demonstrate the effectiveness of the proposed optimization design. PMID:22163743

  12. Interaction strength and model geometry effects on the structure of crossing-shock wave/turbulent boundary-layer interactions

    NASA Technical Reports Server (NTRS)

    Garrison, T. J.; Settles, G. S.

    1993-01-01

    The flowfield structure of a range of symmetric crossing-shock wave/turbulent boundary-layer interactions of varying strength is presented. The test geometry, consisting of a symmetric pair of opposing sharp fins at angle of attack, alpha, mounted to a flat plate, is studied experimentally for a range of alpha from 7 to 15 degrees at Mach numbers of 3 and 4. Results reveal that the basic flowfield shock structure remains similar in nature over the range of interaction strengths examined, with the only changes being in the scale and location of the various features present. The separated flow regions are classified as being either completely or partially separated, the completely separated case being the one in which the entire incoming boundary layer separates from the plate surface. For the current experiments, all but the weakest of the interactions exhibited complete boundary layer separation. Finally, the effects of model geometry are analyzed by comparing data for shock generators of varying lengths, with the results showing no evidence of upstream influence due to the shock generator trailing edges.

  13. Level-crossing statistics of the horizontal wind speed in the planetary surface boundary layer.

    PubMed

    Edwards, Paul J.; Hurst, Robert B.

    2001-09-01

    The probability density of the times for which the horizontal wind remains above or below a given threshold speed is of some interest in the fields of renewable energy generation and pollutant dispersal. However there appear to be no analytic or conceptual models which account for the observed power law form of the distribution of these episode lengths over a range of over three decades, from a few tens of seconds to a day or more. We reanalyze high resolution wind data and demonstrate the fractal character of the point process generated by the wind speed level crossings. We simulate the fluctuating wind speed by a Markov process which approximates the characteristics of the real (non-Markovian) wind and successfully generates a power law distribution of episode lengths. However, fundamental questions concerning the physical basis for this behavior and the connection between the properties of a continuous-time stochastic process and the fractal statistics of the point process generated by its level crossings remain unanswered. (c) 2001 American Institute of Physics.

  14. Antibacterial carboxymethyl cellulose/Ag nanocomposite hydrogels cross-linked with layered double hydroxides.

    PubMed

    Yadollahi, Mehdi; Namazi, Hassan; Aghazadeh, Mohammad

    2015-08-01

    This paper deals with the preparation of antibacterial nanocomposite hydrogels through the combination of carboxy methyl cellulose (CMC), layered double hydroxides (LDH), and silver nanoparticles (AgNPs). CMC-LDH hydrogels were prepared by intercalating CMC into different LDHs. Then, Ag/CMC-LDH nanocomposite hydrogels were prepared through in situ formation of AgNPs within the CMC-LDHs. XRD analysis confirmed the intercalating CMC into the LDH sheets and formation of intercalated structures, as well as formation of AgNPs within the CMC-LDHs. SEM and TEM micrographs indicated well distribution of AgNPs within the Ag/CMC-LDHs. The prepared hydrogels showed a pH sensitive swelling behavior. The Ag/CMC-LDH nanocomposite hydrogels have rather higher swelling in different aqueous solutions in comparison with CMC-LDHs. The antibacterial activity of CMC-LDHs increased considerably after formation of AgNPs and was stable for more than one month.

  15. Computation of a Synthetic Jet in a Turbulent Cross-Flow Boundary Layer

    NASA Technical Reports Server (NTRS)

    Rumsey, Christopher L.

    2004-01-01

    A series of unsteady Reynolds-averaged Navier-Stokes computations are performed for the flow of a synthetic jet issuing into a turbulent boundary layer through a circular orifice. This is one of the validation test cases from a synthetic jet validation workshop held in March 2004. Several numerical parameters are investigated, and the effects of three different turbulence models are explored. Both long-time-averaged and time-dependent phase-averaged results are compared to experiment. On the whole, qualitative comparisons of the mean flow quantities are fairly good. There are many differences evident in the quantitative comparisons. The calculations do not exhibit a strong dependence on the type of turbulence model employed.

  16. Cross-Layer Self-Adaptive/Self-Aware System Software for Exascale Systems

    SciTech Connect

    Gioiosa, Roberto; Kestor, Gokcen; Kerbyson, Darren J.; Hoisie, Adolfy

    2014-10-22

    The extreme level of parallelism coupled with the limited available power budget expected in the exascale era brings unprecedented challenges that demand optimization of performance, power and resiliency in unison. Scalability on such systems is of paramount importance, while power and reliability issues may change the execution environment in which a parallel application runs. To solve these challenges exascale systems will require an introspective system software that combines system and application observations across all system stack layers with online feedback and adaptation mechanisms. In this paper we propose the design of a novel self-aware, self-adaptive system software in which a kernel-level Monitor, which continuously inspects the evolution of the target system through observation of Sensors, is combined with a user-level Controller, which reacts to changes in the execution environment, explores opportunities to increase performance, save power and adapts applications to new execution scenarios. We show that the monitoring system accurately monitors the evolution of parallel applications with a runtime overhead below 1-2%. As a test case, we design and implement a user-runtime system that aims at optimizing application’s performance and system power consumption on complex hierarchical architectures. Our results show that our adaptive system reaches 98% of performance efficiency of manually-tuned applications.

  17. Analytic expressions for Atomic Layer Deposition: coverage, throughput, and materials utilization in cross-flow, particle coating, and spatial ALD

    SciTech Connect

    Yanguas-Gil, Angel; Elam, Jeffrey W.

    2014-05-01

    In this work, the authors present analytic models for atomic layer deposition (ALD) in three common experimental configurations: cross-flow, particle coating, and spatial ALD. These models, based on the plug-flow and well-mixed approximations, allow us to determine the minimum dose times and materials utilization for all three configurations. A comparison between the three models shows that throughput and precursor utilization can each be expressed by universal equations, in which the particularity of the experimental system is contained in a single parameter related to the residence time of the precursor in the reactor. For the case of cross-flow reactors, the authors show how simple analytic expressions for the reactor saturation profiles agree well with experimental results. Consequently, the analytic model can be used to extract information about the ALD surface chemistry (e. g., the reaction probability) by comparing the analytic and experimental saturation profiles, providing a useful tool for characterizing new and existing ALD processes. (C) 2014 American Vacuum Society

  18. Cross Layer Adaptation of Check Intervals in Low Power Listening MAC Protocols for Lifetime Improvement in Wireless Sensor Networks

    PubMed Central

    Escolar, Soledad; Chessa, Stefano; Carretero, Jesús; Marinescu, Maria-Cristina

    2012-01-01

    Preamble sampling-based MAC protocols designed for Wireless Sensor Networks (WSN) are aimed at prolonging the lifetime of the nodes by scheduling their times of activity. This scheduling exploits node synchronization to find the right trade-off between energy consumption and delay. In this paper we consider the problem of node synchronization in preamble sampling protocols. We propose Cross Layer Adaptation of Check intervals (CLAC), a novel protocol intended to reduce the energy consumption of the nodes without significantly increasing the delay. Our protocol modifies the scheduling of the nodes based on estimating the delay experienced by a packet that travels along a multi-hop path. CLAC uses routing and MAC layer information to compute a delay that matches the packet arrival time. We have implemented CLAC on top of well-known routing and MAC protocols for WSN, and we have evaluated our implementation using the Avrora simulator. The simulation results confirm that CLAC improves the network lifetime at no additional packet loss and without affecting the end-to-end delay. PMID:23112613

  19. A Review of Protocol Implementations and Energy Efficient Cross-Layer Design for Wireless Body Area Networks

    PubMed Central

    Hughes, Laurie; Wang, Xinheng; Chen, Tao

    2012-01-01

    The issues inherent in caring for an ever-increasing aged population has been the subject of endless debate and continues to be a hot topic for political discussion. The use of hospital-based facilities for the monitoring of chronic physiological conditions is expensive and ties up key healthcare professionals. The introduction of wireless sensor devices as part of a Wireless Body Area Network (WBAN) integrated within an overall eHealth solution could bring a step change in the remote management of patient healthcare. Sensor devices small enough to be placed either inside or on the human body can form a vital part of an overall health monitoring network. An effectively designed energy efficient WBAN should have a minimal impact on the mobility and lifestyle of the patient. WBAN technology can be deployed within a hospital, care home environment or in the patient's own home. This study is a review of the existing research in the area of WBAN technology and in particular protocol adaptation and energy efficient cross-layer design. The research reviews the work carried out across various layers of the protocol stack and highlights how the latest research proposes to resolve the various challenges inherent in remote continual healthcare monitoring. PMID:23202185

  20. Mass transfer through laminar boundary layer in 2-d microchannels with nonuniform cross section: the effect of wall curvature

    NASA Astrophysics Data System (ADS)

    Pedacchia, Augusta; Adrover, Alessandra

    2012-11-01

    We provide an analytical solution for the combined diffusive and convective 2-d mass transport from a surface film (of arbitrary shape at a given uniform concentration) to a pure solvent flowing in creeping flow conditions into a microchannel, delimited by a flat no-slip surface and by the releasing film itself. Such a problem arises in the study of swelling and dissolution of polimeric thin films under the action of a solvent tangential flow simulating the oral thin film dissolution for drug relase towards the buccal mucosa or oral cavity. We present a similarity solution for laminar forced convection mass (or heat) transfer that generalizes the classical boundary layer solution of the Graetz-Nusselt problem (valid for straight channels or pipes) to a solvent flowing in creeping flow conditions into a 2-d channel with cross-section continuously varying along the axial coordinate x. Close to the releasing boundary, parametrized by a curvilinear abscissa s, both tangential and normal velocity components play a role and their scaling behavior, as a function of wall distance r, should be taken into account in order to have an accurate description of the concentration profile in the boundary layer and of the dependence of the Sherwood number on the curvilinear abscissa s.

  1. Stochastic modelling of intermittent fluctuations in the scrape-off layer: Correlations, distributions, level crossings, and moment estimation

    NASA Astrophysics Data System (ADS)

    Garcia, O. E.; Kube, R.; Theodorsen, A.; Pécseli, H. L.

    2016-05-01

    A stochastic model is presented for intermittent fluctuations in the scrape-off layer of magnetically confined plasmas. The fluctuations in the plasma density are modeled by a super-position of uncorrelated pulses with fixed shape and duration, describing radial motion of blob-like structures. In the case of an exponential pulse shape and exponentially distributed pulse amplitudes, predictions are given for the lowest order moments, probability density function, auto-correlation function, level crossings, and average times for periods spent above and below a given threshold level. Also, the mean squared errors on estimators of sample mean and variance for realizations of the process by finite time series are obtained. These results are discussed in the context of single-point measurements of fluctuations in the scrape-off layer, broad density profiles, and implications for plasma-wall interactions due to the transient transport events in fusion grade plasmas. The results may also have wide applications for modelling fluctuations in other magnetized plasmas such as basic laboratory experiments and ionospheric irregularities.

  2. Facile preparation of Pd nanoparticles supported on single-layer graphene oxide and application for the Suzuki-Miyaura cross-coupling reaction.

    PubMed

    Yamamoto, Shun-ichi; Kinoshita, Hiroshi; Hashimoto, Hideki; Nishina, Yuta

    2014-06-21

    Pd nanoparticles supported on single layer graphene oxide (Pd-slGO) were prepared by gentle heating of palladium(ii) acetate (Pd(OAc)2) and GO in ethanol that served as a mild reductant of the Pd precursor. Pd-slGO showed a high catalytic performance (TON and TOF = 237 000) in the Suzuki-Miyaura cross-coupling reaction.

  3. Genetic parameters for body weight, carcass chemical composition and yield in a broiler-layer cross developed for QTL mapping

    PubMed Central

    Nunes, Beatriz do Nascimento; Ramos, Salvador Boccaletti; Savegnago, Rodrigo Pelicioni; Ledur, Mônica Corrêa; Nones, Kátia; Klein, Claudete Hara; Munari, Danísio Prado

    2011-01-01

    The objective of this study was to estimate genetic and phenotypic correlations of body weight at 6 weeks of age (BW6), as well as final carcass yield, and moisture, protein, fat and ash contents, using data from 3,422 F2 chickens originated from reciprocal cross between a broiler and a layer line. Variance components were estimated by the REML method, using animal models for evaluating random additive genetic and fixed contemporary group (sex, hatch and genetic group) effects. The heritability estimates (h2) for BW6, carcass yield and percentage of carcass moisture were 0.31 ± 0.07, 0.20 ± 0.05 and 0.33 ± 0.07, respectively. The h2 for the percentages of protein, fat and ash on a dry matter basis were 0.48 ± 0.09, 0.55 ± 0.10 and 0.36 ± 0.08, respectively. BW6 had a positive genetic correlation with fat percentage in the carcass, but a negative one with protein and ash contents. Carcass yield, thus, appears to have only low genetic association with carcass composition traits. The genetic correlations observed between traits, measured on a dry matter basis, indicated that selection for carcass protein content may favor higher ash content and a lower percentage of carcass fat. PMID:21931515

  4. Cross layer design for optimised region of interest of ultrasound video data over mobile WiMAX.

    PubMed

    Debono, Carl J; Micallef, Brian W; Philip, Nada Y; Alinejad, Ali; Istepanian, Robert S H; Amso, Nazar N

    2012-11-01

    The application of advanced error concealment techniques applied as a post-process to conceal lost video information in error-prone channels, such as the wireless channel, demand additional processing at the receiver. This increases the delivery delay and needs more computational power. However, in general, only a small region within medical video is of interest to the physician and thus if only this area is considered, the number of computations can be curtailed. In this paper we present a technique whereby the Region of Interest (ROI) specified by the physician is used to delimit the area where the more complex concealment techniques are applied. A cross layer design approach in mobile WiMAX wireless communication environment is adopted in this paper to provide an optimized Quality of Experience (QoE) in the region that matters most to the mobile physician while relaxing the requirements in the background, ensuring real-time delivery. Results show that a diagnostically acceptable Peak Signal-to-Noise-Ratio (PSNR) of about 36 dB can still be achieved within reasonable decoding time. PMID:22652202

  5. Cross layer design for optimised region of interest of ultrasound video data over mobile WiMAX.

    PubMed

    Debono, Carl J; Micallef, Brian W; Philip, Nada Y; Alinejad, Ali; Istepanian, Robert S H; Amso, Nazar N

    2012-11-01

    The application of advanced error concealment techniques applied as a post-process to conceal lost video information in error-prone channels, such as the wireless channel, demand additional processing at the receiver. This increases the delivery delay and needs more computational power. However, in general, only a small region within medical video is of interest to the physician and thus if only this area is considered, the number of computations can be curtailed. In this paper we present a technique whereby the Region of Interest (ROI) specified by the physician is used to delimit the area where the more complex concealment techniques are applied. A cross layer design approach in mobile WiMAX wireless communication environment is adopted in this paper to provide an optimized Quality of Experience (QoE) in the region that matters most to the mobile physician while relaxing the requirements in the background, ensuring real-time delivery. Results show that a diagnostically acceptable Peak Signal-to-Noise-Ratio (PSNR) of about 36 dB can still be achieved within reasonable decoding time.

  6. Wear evaluation of a cross-linked medical grade polyethylene by ultra thin layer activation compared to gravimetry

    NASA Astrophysics Data System (ADS)

    Stroosnijder, Marinus F.; Hoffmann, Michael; Sauvage, Thierry; Blondiaux, Gilbert; Vincent, Laetitia

    2005-01-01

    Most of today's artificial joints rely on an articulating couple consisting of a CoCrMo alloy and a medical grade polyethylene. The wear of the polyethylene component is the major cause for long-term failure of these prostheses since the wear debris leads to adverse biological reactions. The polyethylene wear is usually measured by gravimetric methods, which are limited due to a low sensitivity and accuracy. To demonstrate the reliability of ultra thin layer activation (UTLA) as an alternative technique, wear tests on a cross-linked ultra-high-molecular weight polyethylene (XLPE) sliding against CoCrMo were performed on a wear tester featuring multi-directional sliding motion. The amount of polyethylene wear was evaluated by both UTLA and gravimetry. The particular TLA method used in this work employed the implantation of 7Be radioactive recoils into the polyethylene surface by means of a light mass particle beam. The results indicate that apart from its relatively high sensitivity, UTLA also offers the possibility for on-line measurements of polyethylene wear. This makes it a viable and complementary technique in wear test studies for medical implant purposes especially for those involving wear resistant materials and for rapid wear screening.

  7. Interfacial insertion of a poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) layer between the poly(3-hexyl thiophene) semiconductor and cross-linked poly(vinyl alcohol) insulator layer in organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Cruz-Cruz, Isidro; Tavares, Ana C. B.; Reyes-Reyes, Marisol; López-Sandoval, Román; Hümmelgen, Ivo A.

    2014-02-01

    The role of a thin layer of conductive poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT : PSS), inserted between the gate dielectric and the active layer in poly(3-hexylthiophene)-based transistors was investigated. The devices were fabricated in the bottom-gate top-contact geometry by using cross-linked poly(vinyl alcohol) as the dielectric, whereas the PEDOT : PSS layer was prepared by using an aged aqueous dispersion with addition of different amounts of dimethyl sulfoxide (DMSO) as a secondary dopant. Under these conditions, both a significant reduction in the number of electrically active traps at the interface with the semiconductor and an improvement in the field-effect mobility were obtained, whereas the low power consumption was preserved. The threshold voltage was also displaced by approximately -1 V.

  8. Cross-linking of interfacial layers affects the salt and temperature stability of multilayered emulsions consisting of fish gelatin and sugar beet pectin.

    PubMed

    Zeeb, Benjamin; Fischer, Lutz; Weiss, Jochen

    2011-10-12

    This study assessed the stabilizing effect of enzymatic cross-linking on double-coated emulsions (beet pectin-fish gelatin). The beet pectin layer was cross-linked via ferulic acid groups using laccase (an enzyme that is known to catalyze the oxidation of phenolic groups). Fish gelatin-coated oil droplets (primary emulsion) were mixed at pH 3.5 to promote electrostatic deposition of the beet pectin molecules onto the surfaces of the oil droplets (secondary emulsion). Laccase was then added to promote cross-linking of the adsorbed beet pectin layer. Cross-linked pectin-coated oil droplets had similar or significantly better stability (p < 0.05) than oil droplets of primary or secondary emulsions to NaCl addition (0-500 mM), CaCl(2) addition (0-250 mM), and thermal processing (30-90 °C for 30 min). Freeze-thaw stability and creaming behavior of enzyme-treated, secondary emulsions after two cycles (-8 °C for 22 h; 25 °C for 2 h) were significantly improved (p < 0.05). These results may have important implications for food manufacturers that are in need of emulsions with improved physical stability, for example, emulsions used in frozen foods for sauces or dips.

  9. High-performance HfO x /AlO y -based resistive switching memory cross-point array fabricated by atomic layer deposition.

    PubMed

    Chen, Zhe; Zhang, Feifei; Chen, Bing; Zheng, Yang; Gao, Bin; Liu, Lifeng; Liu, Xiaoyan; Kang, Jinfeng

    2015-01-01

    Resistive switching memory cross-point arrays with TiN/HfO x /AlO y /Pt structure were fabricated. The bi-layered resistive switching films of 5-nm HfO x and 3-nm AlO y were deposited by atomic layer deposition (ALD). Excellent device performances such as low switching voltage, large resistance ratio, good cycle-to-cycle and device-to-device uniformity, and high yield were demonstrated in the fabricated 24 by 24 arrays. In addition, multi-level data storage capability and robust reliability characteristics were also presented. The achievements demonstrated the great potential of ALD-fabricated HfO x /AlO y bi-layers for the application of next-generation nonvolatile memory.

  10. Materials based on carbon-filled porous layers of PVC cyclam derivatives cross-linked with the surfaces of asbestos fabric fibers

    NASA Astrophysics Data System (ADS)

    Tzivadze, A. Yu.; Fridman, A. Ya.; Morozova, E. M.; Sokolova, N. P.; Voloshchuk, A. M.; Petukhova, G. A.; Bardishev, I. I.; Gorbunov, A. M.; Novikov, A. K.; Polyakova, I. Ya.; Titova, V. N.; Yavich, A. A.; Petrova, N. V.

    2016-08-01

    The synthesis of bilayer materials with porous upper layers composed of PVC hydroxyethylcyclam derivatives filled with carbon and a layer consisting of hydroxyethylcyclam, cross-linked via Si-O-C groups with the silica chains of a developed surface of asbestos fabric, is described. The aza-crown groups in these materials are bound with aqua complexes of H2SO4 or NaOH. The structure of the materials is examined, their adsorption characteristics are determined, and the rate of motion of H+ or OH- ions in electrochemical bridges is measured, while the formation of H2 and O2 in their cathodic and anodic polarization is determined as a function of voltage. It is shown that the upper layer of these materials is adsorption-active and electronand H+- or OH-- conductive, while the bottom layer is only H+- or OH-- conductive; through it, the upper layer is supplied with the H+ or OH- ions needed for the regeneration of the aqua complexes broken down to H2 and O2 on carbon particles.

  11. Influence of layer thickness and composition of cross-linked multilayered oil-in-water emulsions on the release behavior of lutein.

    PubMed

    Beicht, Johanna; Zeeb, Benjamin; Gibis, Monika; Fischer, Lutz; Weiss, Jochen

    2013-10-01

    Multilayering and enzymatic cross-linking of emulsions may cause alterations in the release behavior of encapsulated core material due to changes in thickness, porosity and permeability of the membrane. An interfacial engineering technology based on the layer-by-layer electrostatic deposition of oppositively charged biopolymers onto the surfaces of emulsion droplets in combination with an enzymatic treatment was used to generate emulsions with different droplet interfaces to test this hypothesis. Release behavior of primary, secondary (coated) and laccase-treated secondary emulsions carrying lutein, an oxygenated carotenoid, was characterized and studied. Fish gelatin (FG), whey protein isolate (WPI) and dodecyltrimethylammonium bromide (DTAB) were used as primary emulsifiers under acidic conditions (pH 3.5) to facilitate the adsorption of a negatively charged biopolymer (sugar beet pectin). Laccase was added to promote cross-linking of adsorbed beet pectin. The release of lutein-loaded emulsions was investigated and quantified by UV-Vis spectrophotometry. Primary WPI-stabilized emulsions showed a five times higher release of lutein after 48 h than secondary emulsions (pH 3.5). Primary DTAB-stabilized emulsions released 7.2% of encapsulated lutein within the observation period, whereas beet pectin-DTAB-coated emulsions released only 0.13% of lutein. Cross-linking of adsorbed pectin did not significantly decrease release of lutein in comparison to non-cross-linked secondary emulsions. Additionally, release of lutein was also affected by changes in the pH of the surrounding medium. Results suggest that modulating the interfacial properties of oil-in-water emulsion by biopolymer deposition and/or cross-linking may be a useful approach to generate food-grade delivery systems that have specific release-over-time profiles of incorporated active ingredients.

  12. Control of Stationary Cross-Flow Modes in a Mach 3.5 Boundary Layer Using Patterned Passive and Active Roughness

    NASA Technical Reports Server (NTRS)

    Schuele, Chan Yong

    2011-01-01

    Spanwise-periodic roughness designed to excite selected wavelengths of stationary cross- ow modes was investigated in a 3-D boundary layer at Mach 3.5. The test model was a sharp-tipped 14deg right-circular cone. The model and integrated sensor traversing system were placed in the Mach 3.5 Supersonic Low Disturbance Tunnel (SLDT) equipped with a "quiet design" nozzle at the NASA Langley Research Center. The model was oriented at a 4:2deg angle of attack to produce a mean cross-fl ow velocity component in the boundary layer over the cone. Five removable cone tips have been investigated. One has a smooth surface that is used to document the baseline ("natural") conditions. Two had minute (20 - 40 micron) "dimples" that are equally spaced around the circumference, at a streamwise location that is just upstream of the linear stability neutral growth branch for cross- ow modes. The azimuthal mode numbers of the dimpled tips were selected to either enhance the most amplified wave numbers, or to suppress the growth of the most amplified wave numbers. Two of the cone tips had an array of plasma streamwise vortex generators that were designed to simulate the disturbances produced by the passive patterned roughness. The results indicate that the stationary cross-fl ow modes were highly receptive to the patterned roughness of both passive and active types. The patterned passive roughness that was designed to suppress the growth of the most amplified modes had an azimuthal wavelength that was 66% smaller that that of the most amplified stationary cross- ow mode. This had the effect to increase the transition Reynolds number from 25% to 50% depending on the measurement technique. The application of the research is on turbulent transition control on swept wings of supersonic aircraft. The plasma-based roughness has the advantage over the passive roughness of being able to be adaptable to different conditions that would occur during a flight mission.

  13. Influence of layer thickness and composition of cross-linked multilayered oil-in-water emulsions on the release behavior of lutein.

    PubMed

    Beicht, Johanna; Zeeb, Benjamin; Gibis, Monika; Fischer, Lutz; Weiss, Jochen

    2013-10-01

    Multilayering and enzymatic cross-linking of emulsions may cause alterations in the release behavior of encapsulated core material due to changes in thickness, porosity and permeability of the membrane. An interfacial engineering technology based on the layer-by-layer electrostatic deposition of oppositively charged biopolymers onto the surfaces of emulsion droplets in combination with an enzymatic treatment was used to generate emulsions with different droplet interfaces to test this hypothesis. Release behavior of primary, secondary (coated) and laccase-treated secondary emulsions carrying lutein, an oxygenated carotenoid, was characterized and studied. Fish gelatin (FG), whey protein isolate (WPI) and dodecyltrimethylammonium bromide (DTAB) were used as primary emulsifiers under acidic conditions (pH 3.5) to facilitate the adsorption of a negatively charged biopolymer (sugar beet pectin). Laccase was added to promote cross-linking of adsorbed beet pectin. The release of lutein-loaded emulsions was investigated and quantified by UV-Vis spectrophotometry. Primary WPI-stabilized emulsions showed a five times higher release of lutein after 48 h than secondary emulsions (pH 3.5). Primary DTAB-stabilized emulsions released 7.2% of encapsulated lutein within the observation period, whereas beet pectin-DTAB-coated emulsions released only 0.13% of lutein. Cross-linking of adsorbed pectin did not significantly decrease release of lutein in comparison to non-cross-linked secondary emulsions. Additionally, release of lutein was also affected by changes in the pH of the surrounding medium. Results suggest that modulating the interfacial properties of oil-in-water emulsion by biopolymer deposition and/or cross-linking may be a useful approach to generate food-grade delivery systems that have specific release-over-time profiles of incorporated active ingredients. PMID:23978837

  14. The split-cross-bridge resistor for measuring the sheet resistance, linewidth, and line spacing of conducting layers

    NASA Technical Reports Server (NTRS)

    Buehler, M. G.; Hershey, C. W.

    1986-01-01

    A new test structure was developed for evaluating the line spacing between conductors on the same layer using an electrical measurement technique. This compact structure can also be used to measure the sheet resistance, linewidth, and line pitch of the conducting layer. Using an integrated-circuit fabrication process, this structure was fabricated in diffused polycrystalline silicon and metal layers and measured optically and electrically. For the techniques used, the optical measurements were typically one-quarter micron greater than the electrical measurements. Most electrically measured line pitch values were within 2 percent of the designed value. A small difference between the measured and designed line pitch is used to validate sheet resistance, linewidth, and line spacing values.

  15. Limpet Shells from the Aterian Level 8 of El Harhoura 2 Cave (Témara, Morocco): Preservation State of Crossed-Foliated Layers

    PubMed Central

    Nouet, Julius; Chevallard, Corinne; Farre, Bastien; Nehrke, Gernot; Campmas, Emilie; Stoetzel, Emmanuelle; El Hajraoui, Mohamed Abdeljalil; Nespoulet, Roland

    2015-01-01

    The exploitation of mollusks by the first anatomically modern humans is a central question for archaeologists. This paper focuses on level 8 (dated around ∼ 100 ka BP) of El Harhoura 2 Cave, located along the coastline in the Rabat-Témara region (Morocco). The large quantity of Patella sp. shells found in this level highlights questions regarding their origin and preservation. This study presents an estimation of the preservation status of these shells. We focus here on the diagenetic evolution of both the microstructural patterns and organic components of crossed-foliated shell layers, in order to assess the viability of further investigations based on shell layer minor elements, isotopic or biochemical compositions. The results show that the shells seem to be well conserved, with microstructural patterns preserved down to sub-micrometric scales, and that some organic components are still present in situ. But faint taphonomic degradations affecting both mineral and organic components are nonetheless evidenced, such as the disappearance of organic envelopes surrounding crossed-foliated lamellae, combined with a partial recrystallization of the lamellae. Our results provide a solid case-study of the early stages of the diagenetic evolution of crossed-foliated shell layers. Moreover, they highlight the fact that extreme caution must be taken before using fossil shells for palaeoenvironmental or geochronological reconstructions. Without thorough investigation, the alteration patterns illustrated here would easily have gone unnoticed. However, these degradations are liable to bias any proxy based on the elemental, isotopic or biochemical composition of the shells. This study also provides significant data concerning human subsistence behavior: the presence of notches and the good preservation state of limpet shells (no dissolution/recrystallization, no bioerosion and no abrasion/fragmentation aspects) would attest that limpets were gathered alive with tools by

  16. Limpet Shells from the Aterian Level 8 of El Harhoura 2 Cave (Témara, Morocco): Preservation State of Crossed-Foliated Layers.

    PubMed

    Nouet, Julius; Chevallard, Corinne; Farre, Bastien; Nehrke, Gernot; Campmas, Emilie; Stoetzel, Emmanuelle; El Hajraoui, Mohamed Abdeljalil; Nespoulet, Roland

    2015-01-01

    The exploitation of mollusks by the first anatomically modern humans is a central question for archaeologists. This paper focuses on level 8 (dated around ∼ 100 ka BP) of El Harhoura 2 Cave, located along the coastline in the Rabat-Témara region (Morocco). The large quantity of Patella sp. shells found in this level highlights questions regarding their origin and preservation. This study presents an estimation of the preservation status of these shells. We focus here on the diagenetic evolution of both the microstructural patterns and organic components of crossed-foliated shell layers, in order to assess the viability of further investigations based on shell layer minor elements, isotopic or biochemical compositions. The results show that the shells seem to be well conserved, with microstructural patterns preserved down to sub-micrometric scales, and that some organic components are still present in situ. But faint taphonomic degradations affecting both mineral and organic components are nonetheless evidenced, such as the disappearance of organic envelopes surrounding crossed-foliated lamellae, combined with a partial recrystallization of the lamellae. Our results provide a solid case-study of the early stages of the diagenetic evolution of crossed-foliated shell layers. Moreover, they highlight the fact that extreme caution must be taken before using fossil shells for palaeoenvironmental or geochronological reconstructions. Without thorough investigation, the alteration patterns illustrated here would easily have gone unnoticed. However, these degradations are liable to bias any proxy based on the elemental, isotopic or biochemical composition of the shells. This study also provides significant data concerning human subsistence behavior: the presence of notches and the good preservation state of limpet shells (no dissolution/recrystallization, no bioerosion and no abrasion/fragmentation aspects) would attest that limpets were gathered alive with tools by

  17. Numerical simulation of crossing/turbulent boundary layer interaction at Mach 8.3 comparison of zero and two-equation turbulence models

    NASA Technical Reports Server (NTRS)

    Narayanswami, N.; Horstman, C. C.; Knight, D. D.

    1993-01-01

    A 3D hypersonic crossing shock wave/turbulent boundary layer interaction is examined numerically. The test geometry consists of a pair of opposing sharp fins of angle alpha = 15 deg mounted on a flat plate. The freestream Mach number is 8.28. Two theoretical models are evaluated. The full 3D Reynolds-averaged Navier-Stokes equations are solved using the Baldwin-Lomax algebraic turbulent eddy viscosity model and the Rodi turbulence model. Computed results for both cases show good agreement with experiment for flat plate surface pressure and for pitot pressure and yaw angle profiles in the flowfield. General agreement is obtained for surface flow direction. Fair to poor agreement is obtained for surface heat transfer, indicating a need for more accurate turbulence models. The overall flowfield structure is similar to that observed in previous crossing shock interaction studies.

  18. Well-Constructed Single-Layer Molybdenum Disulfide Nanorose Cross-Linked by Three Dimensional-Reduced Graphene Oxide Network for Superior Water Splitting and Lithium Storage Property

    NASA Astrophysics Data System (ADS)

    Zhao, Yanyan; Kuai, Long; Liu, Yanguo; Wang, Pengpeng; Arandiyan, Hamidreza; Cao, Sufeng; Zhang, Jie; Li, Fengyun; Wang, Qing; Geng, Baoyou; Sun, Hongyu

    2015-03-01

    A facile one-step solution reaction route for growth of novel MoS2 nanorose cross-linked by 3D rGO network, in which the MoS2 nanorose is constructed by single-layered or few-layered MoS2 nanosheets, is presented. Due to the 3D assembled hierarchical architecture of the ultrathin MoS2 nanosheets and the interconnection of 3D rGO network, as well as the synergetic effects of MoS2 and rGO, the as-prepared MoS2-NR/rGO nanohybrids delivered high specific capacity, excellent cycling and good rate performance when evaluated as an anode material for lithium-ion batteries. Moreover, the nanohybrids also show excellent hydrogen-evolution catalytic activity and durability in an acidic medium, which is superior to MoS2 nanorose and their nanoparticles counterparts.

  19. A novel technique for preparing a mono-particle layer on a substrate through the epoxy-amino cross-linking

    NASA Astrophysics Data System (ADS)

    Onishi, Shogo; Ogawa, Kazufumi

    2006-12-01

    We present a novel technique for immobilizing nanoparticles on a substrate. This method contains two techniques, which are a preparing technique of self-assembled monomolecular layers (SAMs) terminated in an epoxy group or an amino group on surface of nanoparticles or a substrate and a reaction technique between the epoxy and amino groups. The epoxy terminated SAMs or the amino terminated SAMs were prepared on nanoparticle surfaces or a substrate surface by a chemical adsorption technique using 3-glycidoxypropyltrimethoxysilane or (3-aminopropyl) trimethoxysilane. The particles dispersed in an organic solvent were coated on the substrate, and then the epoxy and amino groups were reacted each other. Unreacted nanoparticles were removed by washing. As a result, the nanoparticles were immobilized to the substrate surface through covalent bonds of the epoxy-amine cross-linking. By using this method, a mono nanoparticle layer could be formed on the substrate.

  20. Well-Constructed Single-Layer Molybdenum Disulfide Nanorose Cross-Linked by Three Dimensional-Reduced Graphene Oxide Network for Superior Water Splitting and Lithium Storage Property

    PubMed Central

    Zhao, Yanyan; Kuai, Long; Liu, Yanguo; Wang, Pengpeng; Arandiyan, Hamidreza; Cao, Sufeng; Zhang, Jie; Li, Fengyun; Wang, Qing; Geng, Baoyou; Sun, Hongyu

    2015-01-01

    A facile one-step solution reaction route for growth of novel MoS2 nanorose cross-linked by 3D rGO network, in which the MoS2 nanorose is constructed by single-layered or few-layered MoS2 nanosheets, is presented. Due to the 3D assembled hierarchical architecture of the ultrathin MoS2 nanosheets and the interconnection of 3D rGO network, as well as the synergetic effects of MoS2 and rGO, the as-prepared MoS2-NR/rGO nanohybrids delivered high specific capacity, excellent cycling and good rate performance when evaluated as an anode material for lithium-ion batteries. Moreover, the nanohybrids also show excellent hydrogen-evolution catalytic activity and durability in an acidic medium, which is superior to MoS2 nanorose and their nanoparticles counterparts. PMID:25735416

  1. Enhanced performance of polymer solar cell with ZnO nanoparticle electron transporting layer passivated by in situ cross-linked three-dimensional polymer network

    NASA Astrophysics Data System (ADS)

    Wu, Zhongwei; Song, Tao; Xia, Zhouhui; Wei, Huaixin; Sun, Baoquan

    2013-12-01

    An in situ cross-linked three-dimensional polymer network has been developed to passivate ZnO nanoparticles as an electron transporting layer (ETL) to improve the performance of inverted organic solar cells. The passivated ZnO ETL-based devices achieve efficiencies of 3.26% for poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and 7.37% for poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b‧]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl

  2. Concerning the interaction of non-stationary cross-flow vortices in a three-dimensional boundary layer

    NASA Technical Reports Server (NTRS)

    Bassom, Andrew P.; Hall, Philip

    1990-01-01

    Recently there has been much work devoted to considering some of the many and varied interaction mechanisms which may be operative in three-dimensional boundary layer flows. This paper is concerned with resonant triads of crossflow vortices. The effects of interactions upon resonant triads is examined where each member of the triad has the property of being linearly neutrally stable so that the importance of the interplay between modes can be relatively easily assessed. Modes within the boundary layer flow above a rotating disc are investigated because of the similarity between this disc flow and many important practical flows and, secondly, because the selected flow is an exact solution of the Navier-Stokes equations which makes its theoretical analysis especially attractive. It is demonstrated that the desired triads of linearly neutrally stable modes can exist within the chosen boundary layer flow. Evolution equations are obtained to describe the development of the amplitudes of these modes once the interaction mechanism is accounted for. It is found that the coefficients of the interaction terms within the evolution equations are, in general, given by quite intricate expressions although some elementary numerical work shows that the evaluation of these coefficients is practicable. The basis of the work lends itself to generalization to more complicated boundary layers, and effects of detuning or non-parallelism could be provided for within the asymptotic framework.

  3. A Framework for Supporting Survivability, Network Planning and Cross-Layer Optimization in Future Multi-Domain Terabit Networks

    SciTech Connect

    Baldin, Ilya; Huang, Shu; Gopidi, Rajesh

    2015-01-28

    This final project report describes the accomplishments, products and publications from the award. It includes the overview of the project goals to devise a framework for managing resources in multi-domain, multi-layer networks, as well the details of the mathematical problem formulation and the description of the prototype built to prove the concept.

  4. An Improved Cross-Layering Design for IPv6 Fast Handover with IEEE 802.16m Entry Before Break Handover

    NASA Astrophysics Data System (ADS)

    Kim, Ronny Yongho; Jung, Inuk; Kim, Young Yong

    IEEE 802.16m is an advanced air interface standard which is under development for IMT-Advanced systems, known as 4G systems. IEEE 802.16m is designed to provide a high data rate and a Quality of Service (QoS) level in order to meet user service requirements, and is especially suitable for mobilized environments. There are several factors that have great impact on such requirements. As one of the major factors, we mainly focus on latency issues. In IEEE 802.16m, an enhanced layer 2 handover scheme, described as Entry Before Break (EBB) was proposed and adopted to reduce handover latency. EBB provides significant handover interruption time reduction with respect to the legacy IEEE 802.16 handover scheme. Fast handovers for mobile IPv6 (FMIPv6) was standardized by Internet Engineering Task Force (IETF) in order to provide reduced handover interruption time from IP layer perspective. Since FMIPv6 utilizes link layer triggers to reduce handover latency, it is very critical to jointly design FMIPv6 with its underlying link layer protocol. However, FMIPv6 based on new handover scheme, EBB has not been proposed. In this paper, we propose an improved cross-layering design for FMIPv6 based on the IEEE 802.16m EBB handover. In comparison with the conventional FMIPv6 based on the legacy IEEE 802.16 network, the overall handover interruption time can be significantly reduced by employing the proposed design. Benefits of this improvement on latency reduction for mobile user applications are thoroughly investigated with both numerical analysis and simulation on various IP applications.

  5. Cross-stacked carbon nanotube film as an additional built-in current collector and adsorption layer for high-performance lithium sulfur batteries

    NASA Astrophysics Data System (ADS)

    Sun, Li; Kong, Weibang; Li, Mengya; Wu, Hengcai; Jiang, Kaili; Li, Qunqing; Zhang, Yihe; Wang, Jiaping; Fan, Shoushan

    2016-02-01

    Cross-stacked carbon nanotube (CNT) film is proposed as an additional built-in current collector and adsorption layer in sulfur cathodes for advanced lithium sulfur (Li-S) batteries. On one hand, the CNT film with high conductivity, microstructural rough surface, high flexibility and mechanical durability retains stable and direct electronic contact with the sulfur cathode materials, therefore decreasing internal resistivity and suppressing polarization of the cathode. On the other hand, the highly porous structure and the high surface area of the CNT film provide abundant adsorption points to support and confine sulfur cathode materials, alleviate their aggregation and promote high sulfur utilization. Moreover, the lightweight and compact structure of the CNT film adds no extra weight or volume to the sulfur cathode, benefitting the improvement of energy densities. Based on these characteristics, the sulfur cathode with a 100-layer cross-stacked CNT film presents excellent rate performances with capacities of 986, 922 and 874 mAh g-1 at cycling rates of 0.2C, 0.5C and 1C for sulfur loading of 60 wt%, corresponding to an improvement of 52%, 109% and 146% compared to that without a CNT film. Promising cycling performances are also demonstrated, offering great potential for scaled-up production of sulfur cathodes for Li-S batteries.

  6. Seasonal Ozone Variations in the Isentropic Layer between 330 and 380 K as Observed by SAGE 2: Implications of Extratropical Cross-Tropopause Transport

    NASA Technical Reports Server (NTRS)

    Wang, Pi-Huan; Cunnold, Derek M.; Zawodny, Joseph M.; Pierce, R. Bradley; Olson, Jennifer R.; Kent, Geoffrey S.; Skeens, Kristi, M.

    1998-01-01

    To provide observational evidence on the extratropical cross-tropopause transport between the stratosphere and the troposphere via quasi-isentropic processes in the middleworld (the part of the atmosphere in which the isentropic surfaces intersect the tropopause), this report presents an analysis of the seasonal variations of the ozone latitudinal distribution in the isentropic layer between 330 K and 380 K based on the measurements from the Stratospheric Aerosol and Gas Experiment (SAGE) II. The results from SAGE II data analysis are consistent with (1) the buildup of ozone-rich air in the extratropical middleworld through the large-scale descending mass circulation during winter, (2) the spread of ozone-rich air in the isentropic layer from midlatitudes to subtropics via quasi-isentropic transport during spring, (3) significant photochemical ozone removal and the absence of an ozone-rich supply of air to the layer during summer, and (4) air mass exchange between the subtropics and the extratropics during the summer monsoon period. Thus the SAGE II observed ozone seasonal variations in the middleworld are consistent with the existing model calculated annual cycle of the diabatic circulation as well as the conceptual role of the eddy quasi-adiabatic transport in the stratosphere-troposphere exchange reported in the literature.

  7. Crossing shock wave turbulent boundary layer interactions - Variable angle and shock generator length geometry effects at Mach 3

    NASA Technical Reports Server (NTRS)

    Bogdonoff, S. M.; Stokes, W. L.

    1992-01-01

    By comparing the detailed wall static pressure distributions for 9 inch and 11 inch long fins generating a crossing shock configuration at M = 2.93, the high resolution results of the 9 inch fins are shown to be free of exit effects. Analysis of the static pressure profiles have delineated the limited regions where the single fin results are valid. The characteristics of the complex interaction, with varying shock wave strength, have been described. The data provide a critical test for computational fluid dynamics which, in its initial phase, has performed poorly in predicting the measured wall static pressure distributions.

  8. Laser Interferometer Skin-Friction measurements of crossing-shock wave/turbulent boundary-layer interactions

    NASA Technical Reports Server (NTRS)

    Garrison, T. J.; Settles, G. S.

    1993-01-01

    Wall shear stress measurements beneath crossingshock wave/turbulent boundary-layer interactions have been made for three interactions of different strengths. The interactions are generated by two sharp fins at symmetric angles of attack mounted on a flat plate. The shear stress measurements were made for fin angles of 7 and 11 degrees at Mach 3 and 15 degrees at Mach 4. The measurements were made using a Laser Interferometer Skin Friction (LISF) meter; a device which determines the wail shear by optically measuring the time rate of thinning of an oil film placed on the test model surface. Results of the measurements reveal high skin friction coefficients in the vicinity of the fin/plate junction and the presence of quasi-two-dimensional flow separation on the interaction centerline. Additionally, two Navier-Stokes computations, one using a Baldwin-Lomax turbulence model and one using a k- model, are compared to the experimental results for the Mach 4, 15 degree interaction case. While the k- model did a reasonable job of predicting the overall trend in portions of the skin friction distribution, neither computation fully captured the physics of the near surface flow in this complex interaction.

  9. Layered Signaling Regulatory Networks Analysis of Gene Expression Involved in Malignant Tumorigenesis of Non-Resolving Ulcerative Colitis via Integration of Cross-Study Microarray Profiles

    PubMed Central

    Fan, Shengjun; Pan, Zhenyu; Geng, Qiang; Li, Xin; Wang, Yefan; An, Yu; Xu, Yan; Tie, Lu; Pan, Yan; Li, Xuejun

    2013-01-01

    Background Ulcerative colitis (UC) was the most frequently diagnosed inflammatory bowel disease (IBD) and closely linked to colorectal carcinogenesis. By far, the underlying mechanisms associated with the disease are still unclear. With the increasing accumulation of microarray gene expression profiles, it is profitable to gain a systematic perspective based on gene regulatory networks to better elucidate the roles of genes associated with disorders. However, a major challenge for microarray data analysis is the integration of multiple-studies generated by different groups. Methodology/Principal Findings In this study, firstly, we modeled a signaling regulatory network associated with colorectal cancer (CRC) initiation via integration of cross-study microarray expression data sets using Empirical Bayes (EB) algorithm. Secondly, a manually curated human cancer signaling map was established via comprehensive retrieval of the publicly available repositories. Finally, the co-differently-expressed genes were manually curated to portray the layered signaling regulatory networks. Results Overall, the remodeled signaling regulatory networks were separated into four major layers including extracellular, membrane, cytoplasm and nucleus, which led to the identification of five core biological processes and four signaling pathways associated with colorectal carcinogenesis. As a result, our biological interpretation highlighted the importance of EGF/EGFR signaling pathway, EPO signaling pathway, T cell signal transduction and members of the BCR signaling pathway, which were responsible for the malignant transition of CRC from the benign UC to the aggressive one. Conclusions The present study illustrated a standardized normalization approach for cross-study microarray expression data sets. Our model for signaling networks construction was based on the experimentally-supported interaction and microarray co-expression modeling. Pathway-based signaling regulatory networks analysis

  10. Modeling of Turbulent Boundary Layer Surface Pressure Fluctuation Auto and Cross Spectra - Verification and Adjustments Based on TU-144LL Data

    NASA Technical Reports Server (NTRS)

    Rackl, Robert; Weston, Adam

    2005-01-01

    The literature on turbulent boundary layer pressure fluctuations provides several empirical models which were compared to the measured TU-144 data. The Efimtsov model showed the best agreement. Adjustments were made to improve its agreement further, consisting of the addition of a broad band peak in the mid frequencies, and a minor modification to the high frequency rolloff. The adjusted Efimtsov predicted and measured results are compared for both subsonic and supersonic flight conditions. Measurements in the forward and middle portions of the fuselage have better agreement with the model than those from the aft portion. For High Speed Civil Transport supersonic cruise, interior levels predicted by use of this model are expected to increase by 1-3 dB due to the adjustments to the Efimtsov model. The space-time cross-correlations and cross-spectra of the fluctuating surface pressure were also investigated. This analysis is an important ingredient in structural acoustic models of aircraft interior noise. Once again the measured data were compared to the predicted levels from the Efimtsov model.

  11. Effect of cross-field drifts on flows in the main scrape-off-layer of DIII-D L-mode plasmas

    SciTech Connect

    Groth, M.; Boedo, J.A.; Brooks, N. H.; Isler, R. C.; Leonard, A. W.; Porter, G. D.; Watkins, J. G.; West, W. P.; Bray, Brad D; Fenstermacher, M. E.; Groebner, R.; Moyer, R.A.; Rudakov, D.L.; Yu, J.H.; Zeng, L.

    2009-01-01

    The flow velocities of deuterons and low charge-state carbon ions have been measured simultaneously in the main scrape-off-layer (SOL) in low-density plasmas in DIII-D, and the dependences of these flow fields on the direction of the cross-field drifts (E x B and B x del B) have been investigated. These measurements were taken poloidally localized in the SOL region vertically opposite the divertor X-point. The carbon ion flows do not necessarily match those of the deuterons either in the direction with respect to the magnetic field lines or in magnitude, suggesting that physics effects apart from entrainment play a significant role in the impurity response. In configurations with the ion B x del B drift towards the divertor X-point, the parallel-B deuteron velocities at the plasma crown are high (-20 to -30 km s(-1) in the direction of the high field side (HFS) divertor), while they are nearly zero in configurations with the opposite B x del B drift direction. The flow direction of singly and doubly charged carbon ions is independent of the ion B x del B drift direction, and the ions flow at approximately -5 to -10 km s(-1) towards the HFS divertor. Simulations with the UEDGE code have been carried out to better understand the underlying physics processes. Inclusion of cross-field drifts in the simulations produced divertor solutions for density and temperature that agree significantly better with measured divertor parameters. These simulations do not, however, reproduce the measured flow fields at the crown for the configuration with the ion B x del B drift towards the divertor X-point. The UEDGE code has also been used to understand the influence of pumping at the HFS divertor plate, and a poloidal dependence in the radial transport coefficient.

  12. A Stillinger-Weber potential for single-layered black phosphorus, and the importance of cross-pucker interactions for a negative Poisson's ratio and edge stress-induced bending

    NASA Astrophysics Data System (ADS)

    Jiang, Jin-Wu; Rabczuk, Timon; Park, Harold S.

    2015-03-01

    The distinguishing structural feature of single-layered black phosphorus is its puckered structure, which leads to many novel physical properties. In this work, we first present a new parameterization of the Stillinger-Weber potential for single-layered black phosphorus. In doing so, we reveal the importance of a cross-pucker interaction term in capturing its unique mechanical properties, such as a negative Poisson's ratio. In particular, we show that the cross-pucker interaction enables the pucker to act as a re-entrant hinge, which expands in the lateral direction when it is stretched in the longitudinal direction. As a consequence, single-layered black phosphorus has a negative Poisson's ratio in the direction perpendicular to the atomic plane. As an additional demonstration of the impact of the cross-pucker interaction, we show that it is also the key factor that enables capturing the edge stress-induced bending of single-layered black phosphorus that has been reported in ab initio calculations.

  13. Cross-sectional dopant profiling and depletion layer visualization of SiC power double diffused metal-oxide-semiconductor field effect transistor using super-higher-order nonlinear dielectric microscopy

    NASA Astrophysics Data System (ADS)

    Chinone, N.; Nakamura, T.; Cho, Y.

    2014-08-01

    The dopant distribution and depletion layer in a cross-section of a SiC double diffused MOSFET (DMOSFET) is visualized using super-higher-order scanning nonlinear dielectric microscopy (SHO-SNDM), which is a form of scanning probe microscopy. Analysis of the data acquired by SHO-SNDM clarifies the dopant distribution in great detail, which is otherwise difficult to detect using conventional scanning capacitance microscopy or scanning microwave microscopy. Moreover, the newly developed SHO-SNDM method enables us to distinguish the n-type, p-type, and depletion layer regions very clearly, and they are found to be consistent with the general DMOSFET structure.

  14. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Mechanism for propagation of rate signals through a 10-layer feedforward neuronal network

    NASA Astrophysics Data System (ADS)

    Li, Jie; Yu, Wan-Qing; Xu, Ding; Liu, Feng; Wang, Wei

    2009-12-01

    Using numerical simulations, we explore the mechanism for propagation of rate signals through a 10-layer feedforward network composed of Hodgkin-Huxley (HH) neurons with sparse connectivity. When white noise is afferent to the input layer, neuronal firing becomes progressively more synchronous in successive layers and synchrony is well developed in deeper layers owing to the feedforward connections between neighboring layers. The synchrony ensures the successful propagation of rate signals through the network when the synaptic conductance is weak. As the synaptic time constant τsyn varies, coherence resonance is observed in the network activity due to the intrinsic property of HH neurons. This makes the output firing rate single-peaked as a function of τsyn, suggesting that the signal propagation can be modulated by the synaptic time constant. These results are consistent with experimental results and advance our understanding of how information is processed in feedforward networks.

  15. Reduction of cross-talks between circuit and sensor layer in the Kyoto's X-ray astronomy SOI pixel sensors with Double-SOI wafer

    NASA Astrophysics Data System (ADS)

    Ohmura, Shunichi; Tsuru, Takeshi Go; Tanaka, Takaaki; Uchida, Hiroyuki; Takeda, Ayaki; Matsumura, Hideaki; Ito, Makoto; Arai, Yasuo; Kurachi, Ikuo; Miyoshi, Toshinobu; Nakashima, Shinya; Mori, Koji; Nishioka, Yusuke; Takebayashi, Nobuaki; Noda, Koki; Kohmura, Takayoshi; Tamasawa, Kouki; Ozawa, Yusuke; Sato, Tadashi; Konno, Takahiro; Kawahito, Shoji; Kagawa, Keiichiro; Yasutomi, Keita; Kamehama, Hiroki; Shrestha, Sumeet; Hara, Kazuhiko; Honda, Shunsuke

    2016-09-01

    We have been developing silicon-on-insulator pixel sensors, "XRPIXs," for future X-ray astronomy satellites. XRPIXs are equipped with a function of "event-driven readout," with which we can read out only hit pixels by trigger signals and hence realize good time resolution reaching ∼ 10 μs . The current version of XRPIX suffers from a problem that the spectral performance degrades in the event-driven readout mode compared to the frame-readout mode, in which all the pixels are read out serially. Previous studies have clarified that one of the causes is capacitive coupling between the sense node and the trigger signal line in the circuit layer. In order to solve the problem, we adopt the Double SOI structure having a middle silicon layer between the circuit and the sensor layers. We expect the middle silicon layer to work as an electrostatic shield and reduces the capacitive coupling. In this paper, we report the spectroscopic performance of XRPIX with the middle silicon layer. We successfully reduce the capacitive coupling and the readout noise.

  16. A Comparative SEM Investigation of Smear Layer Remaining on Dentinal Walls by Three Rotary NiTi Files with Different Cross Sectional Designs in Moderately Curved Canals

    PubMed Central

    Kakkar, Pooja; Vats, Asit

    2015-01-01

    Objective: The objective of this study was to compare the smear layer formed on root canal walls during canal preparation of extracted human teeth by Twisted, Mtwo, and ProTaper rotary nickel titanium instruments. Materials and Methods: Sixty single rooted human premolar teeth with root curvature <250 were selected and randomly divided into three Groups (n= 20 teeth per Group). Three types of rotary nickel titanium instruments were used, Twisted (SybronEndo, Orange, CA, USA), Mtwo (VDW, Munich, Germany) and ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) according to manufacturer’s instructions to instrument the root canals. Irrigation for all groups was performed after each instrument change with 3ml of 3% sodium hypochlorite followed by Glyde (File Prep, Dentsply, Maillefer, Ballaigues, Switzerland) as chelator paste and lubricant. Three different areas (coronal, middle and apical thirds) of the root canal were evaluated using scanning electron microscopy (SEM). The canal wall of each sample was assessed and compared using a predefined scale for the presence or absence of smear layer. Data were analysed statistically using ANOVA and Tukey HSD test Results: All three groups showed statistically significant more smear layer in the apical thirds of the canal as compared to the coronal and middle thirds (p<0.001). Mtwo rotary file system produced significantly less smear layer (p<0.001) compared to Twisted and ProTaper rotary instruments in the apical portion. Twisted Files resulted in less smear layer formation in the apical thirds of the canal compared to ProTaper rotary instruments but were statistically insignificant. Conclusion: Completely clean root canals were not found after instrumentation with any of the three instruments. Under the confines of this study Mtwo instruments produced significantly cleaner dentin wall surfaces throughout the canal length in comparison to Twisted and ProTaper rotary files. Twisted Files proved to be comparable to Pro

  17. Polar Layers

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA02153 Polar Layers

    This image of the south polar region shows layered material. It is not known if the layers are formed yearly or if they form over the period of 10s to 100s of years or more.

    Image information: VIS instrument. Latitude -80.3N, Longitude 296.2E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  18. Layered semiconductor neutron detectors

    DOEpatents

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  19. A model for transition by attachment-line contamination and an examination of cross-flow instability in 3-D boundary layers

    NASA Astrophysics Data System (ADS)

    Stewart, I. R.; Poll, D. I. A.

    A model for predicting the development of intermittent turbulence in a boundary layer flow downstream of a large 2-D circular trip on an attachment-line was produced. It gives good predictions of intermittency at any point in the flow. Stability calculations were performed for the Falkner-Skan-Cooke family of boundary layers using linear stability theory. A relationship for the minimum critical Reynolds number and the height of the inflection point in the profile is identified. This correlation gives good agreement with the stability characteristics for boundary layer profiles typical of those occurring on suction wings. A discrepancy in previous empirical relations between skin friction and Reynolds number in fully developed turbulent flow on an attachment-line is discovered. To investigate this an experiment was undertaken using Preston tubes and a Pitot tube with the Clauser Chart method. An accurate correlation of skin friction on an attachment-line was determined from the experimental data. Small diameter Preston tubes underestimate skin friction on an attachment-line to the order of 10 percent which is not inconsistent with a reduction of the effective measurement height, possibly due to vortex shedding in the divergent flow at the mouth of the tube.

  20. Effect of Cross-Field Drifts and Core Rotation on Flows in the Main Scrape-Off Layer of DIII-D L-mode Plasmas

    SciTech Connect

    Groth, M; Boedo, J A; Brooks, N H; Isler, R C; Leonard, A W; Porter, G D; Watkins, J G; West, W P; Bray, B D; Fenstermacher, M E; Groebner, R J; Moyer, R A; Rudakov, D L; Yu, J H; Zeng, L

    2008-10-13

    The flow velocities of deuterons and low charge-state carbon ions have been measured simultaneously for the first time at the crown of the main SOL for low-density plasmas in DIII-D. The dependences of the flow fields on the direction of the cross-field drifts (E x B and B x {del}B) and core plasma rotation were investigated. The measurements indicate that the carbon ion flow direction and magnitude along the magnetic field lines are not necessarily determined by the deuteron flow field, but other physics must also play a role. The deuteron velocities at the plasma crown are high (20-30 km/s) in configurations with the ion B x {del}B drift toward the divertor X-point, while nearly zero in configurations with the opposite B x {del}B drift direction. The flow velocities of doubly charged carbon ions are independent of the ion B x {del}B drift direction, and the measurements suggest a stagnation point in the flow field at the crown of the plasma. Both deuteron and carbon ion flow velocities in the SOL were found to be independent of the direction of core plasma rotation. Simulations with the UEDGE code have been carried out to better understand the underlying physics processes. Including the cross-field drifts in the simulations produced divertor solutions that are in significantly closer agreement with the measurements. They do not, however, reproduce the measured flow fields at the crown for the configuration with the ion B x {del}B drift toward the divertor X-point.

  1. Investigation of the foam influence on the wind-wave momentum exchange and cross-polarization microwave radar return within laboratory modeling of atmosphere-ocean boundary layer

    NASA Astrophysics Data System (ADS)

    Sergeev, Daniil; Troitskaya, Yuliya; Vdovin, Maxim; Ermoshkin, Alexey

    2016-04-01

    The effect of foam presence on the transfer processes and the parameters of the surface roughness within the laboratory simulation of wind-wave interaction was carried out on the Thermostratified Wind-Wave Tank (TSWiWaT) IAP, using a specially designed foam generator. The parameters of air flow profiles and waves elevation were measured with scanning Pitot gauge and wire wave gauges respectively in the range of equivalent wind speed U10 from 12 to 38 m/s (covering strong winds) on the clean water and with foam. It was shown that the foam reduces the amplitudes and slopes of the waves in comparison with the clean water in the hole range of wind speeds investigated, and the peak frequency and wave numbers remain almost constant. The drag coefficient calculating by profiling method demonstrated similar behavior (almost independent on U10) for case of foam and increased compared with clear water, particularly noticeable for low wind speeds. Simultaneously the investigations of influence of the foam on the peculiarity of the microwave radio back scattering of X-diapason was investigated. These measurements were carried for different sensing angles (30, 40 i 50 degrees from vertical) and for four polarizations: co-polarized HH and VV, and de-polarized HV and VH. It was shown that foam leads to decrease of specific radar cross section of the wavy surface in comparison with clean water. The work was supported by the Russian Foundation for Basic Research (grants No. 15-35-20953, 14-05-00367, 16-55-52022) and project ASIST of FP7. The experiment is supported by Russian Science Foundation (Agreement No. 15-17-20009), radilocation measurments are partially supported by Russian Science Foundation (Agreement No. 14-17-00667).

  2. Regenerator cross arm seal assembly

    DOEpatents

    Jackman, Anthony V.

    1988-01-01

    A seal assembly for disposition between a cross arm on a gas turbine engine block and a regenerator disc, the seal assembly including a platform coextensive with the cross arm, a seal and wear layer sealingly and slidingly engaging the regenerator disc, a porous and compliant support layer between the platform and the seal and wear layer porous enough to permit flow of cooling air therethrough and compliant to accommodate relative thermal growth and distortion, a dike between the seal and wear layer and the platform for preventing cross flow through the support layer between engine exhaust and pressurized air passages, and air diversion passages for directing unregenerated pressurized air through the support layer to cool the seal and wear layer and then back into the flow of regenerated pressurized air.

  3. Polar Layers

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03581 Polar Layers

    This image shows just one example of the bright and dark markings that appear during summer time. The marks are related to the polar layers. If you happen to see a wild-eyed guy sticking his tongue out at you, you'll know why this image qualifies for the old 'art' category of THEMIS releases.

    Image information: VIS instrument. Latitude 80.6S, Longitude 34.1E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  4. Layered Fan

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03692 Layered Fan

    This beautiful fan deposit is located at the end of a mega-gully that empties into the southern trough of Coprates Chasma.

    Image information: VIS instrument. Latitude -14.9N, Longitude 299.8E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  5. Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross ...

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

    Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross Bracing Detail, Vertical Cross Bracing-End Detail - Cumberland Covered Bridge, Spanning Mississinewa River, Matthews, Grant County, IN

  6. Comparative analysis of quantitative trait loci for body weight, growth rate and growth curve parameters from 3 to 72 weeks of age in female chickens of a broiler–layer cross

    PubMed Central

    2013-01-01

    Background Comparisons of quantitative trait loci (QTL) for growth and parameters of growth curves assist in understanding the genetics and ultimately the physiology of growth. Records of body weight at 3, 6, 12, 24, 48 and 72 weeks of age and growth rate between successive age intervals of about 500 F2 female chickens of the Roslin broiler-layer cross were available for analysis. These data were analysed to detect and compare QTL for body weight, growth rate and parameters of the Gompertz growth function. Results Over 50 QTL were identified for body weight at specific ages and most were also detected in the nearest preceding and/or subsequent growth stage. The sum of the significant and suggestive additive effects for bodyweight at specific ages accounted for 23-43% of the phenotypic variation. A single QTL for body weight on chromosome 4 at 48 weeks of age had the largest additive effect (550.4 ± 68.0 g, 11.5% of the phenotypic variation) and a QTL at a similar position accounted 14.5% of the phenotypic variation at 12 weeks of age. Age specific QTL for growth rate were detected suggesting that there are specific genes that affect developmental processes during the different stages of growth. Relatively few QTL influencing Gompertz growth curve parameters were detected and overlapped with loci affecting growth rate. Dominance effects were generally not significant but from 12 weeks of age they exceeded the additive effect in a few cases. No evidence for epistatic QTL pairs was found. Conclusions The results confirm the location for body weight and body weight gain during growth that were identified in previous studies and were consistent with QTL for the parameters of the Gompertz growth function. Chromosome 4 explained a relatively large proportion of the observed growth variation across the different ages, and also harboured most of the detected QTL for Gompertz parameters, confirming its importance in controlling growth. Very few QTL were detected

  7. Boundary Layer

    NASA Technical Reports Server (NTRS)

    Loitsianskii. L. G.

    1956-01-01

    The fundamental, practically the most important branch of the modern mechanics of a viscous fluid or a gas, is that branch which concerns itself with the study of the boundary layer. The presence of a boundary layer accounts for the origin of the resistance and lift force, the breakdown of the smooth flow about bodies, and other phenomena that are associated with the motion of a body in a real fluid. The concept of boundary layer was clearly formulated by the founder of aerodynamics, N. E. Joukowsky, in his well-known work "On the Form of Ships" published as early as 1890. In his book "Theoretical Foundations of Air Navigation," Joukowsky gave an account of the most important properties of the boundary layer and pointed out the part played by it in the production of the resistance of bodies to motion. The fundamental differential equations of the motion of a fluid in a laminar boundary layer were given by Prandtl in 1904; the first solutions of these equations date from 1907 to 1910. As regards the turbulent boundary layer, there does not exist even to this day any rigorous formulation of this problem because there is no closed system of equations for the turbulent motion of a fluid. Soviet scientists have done much toward developing a general theory of the boundary layer, and in that branch of the theory which is of greatest practical importance at the present time, namely the study of the boundary layer at large velocities of the body in a compressed gas, the efforts of the scientists of our country have borne fruit in the creation of a new theory which leaves far behind all that has been done previously in this direction. We shall herein enumerate the most important results by Soviet scientists in the development of the theory of the boundary layer.

  8. Layers in Melas Chasma

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Click on image for larger annotated version

    This scene of layered deposits is from Melas Chasma, part of the Valles Marineris valley network. The area consists of a series of plateaus and cliffs that form a step-like terrain similar to the Grand Staircase-Escalante region of southwest Utah. The upper-right half of the image covers the highest plateau, and lower cliffs and plateaus step down in elevation toward the lower left of the image. Dunes of dark sand commonly cover the flat plateaus and distinct layers of bedrock are exposed in the cliffs. The orientations of these layers may help scientists to understand how the layers formed and the kind of environment that the layers formed in. Black rectangles on the left side of the image are areas where the image data was lost during transmission from Mars Reconnaissance Orbiter to Earth. This subscene [above] shows a series of boulder tracks on the left side of the image. The boulders fell from the cliffs above and left behind a series of small depressions. Each depression was made as the boulder bounced and rolled along the surface. In many cases, the tracks can be followed to the specific boulder that made them. Also visible in this subscene are cross-sections through the layered bedrock. This bedrock likely formed through settling of sand-sized particles out of the air or out of a body of water that has since drained away. These layers are 'cross-bedded', which means that subsequent layers are not parallel to each other but are instead oriented at an angle to other layers. The fact that these layers are cross-bedded indicates that the sand-sized particles were moved horizontally along the surface as they settled, just like sand dunes or ripples at the bottom of a stream. The size and shape of these cross-beds may help scientists to determine if the layers formed underwater or on land.

    Image PSP_001377_1685 was taken by the High Resolution Imaging

  9. Layers and Erosion and more Layers

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 4 November 2003

    This image is located within a set of eroded layered rocks known as the Medusae Fossae Formation. Careful inspection of this image reveals four separate layers. Starting at the bottom of the image, as well as the bottom of the sequence of layers, is a somewhat hilly, cratered plain. Above that is a mud or lava flow with a lobate edge that is characteristic of fluid flow. Above that is a layer with a spectacular rayed crater. This layer shows linear erosional patterns that are probably caused by persistent wind abrasion, typical of rocks in this area. And finally, a more blocky unit lies on top, mostly eroded away.

    Image information: VIS instrument. Latitude 3.6, Longitude 218.6 East (141.4 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  10. Nanostructure Neutron Converter Layer Development

    NASA Technical Reports Server (NTRS)

    Park, Cheol (Inventor); Sauti, Godfrey (Inventor); Kang, Jin Ho (Inventor); Lowther, Sharon E. (Inventor); Thibeault, Sheila A. (Inventor); Bryant, Robert G. (Inventor)

    2016-01-01

    Methods for making a neutron converter layer are provided. The various embodiment methods enable the formation of a single layer neutron converter material. The single layer neutron converter material formed according to the various embodiments may have a high neutron absorption cross section, tailored resistivity providing a good electric field penetration with submicron particles, and a high secondary electron emission coefficient. In an embodiment method a neutron converter layer may be formed by sequential supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In another embodiment method a neutron converter layer may be formed by simultaneous supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In a further embodiment method a neutron converter layer may be formed by in-situ metalized aerogel nanostructure development.

  11. Spallanzani Layers

    NASA Technical Reports Server (NTRS)

    2006-01-01

    31 March 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a layered, light-toned mesa among other layered materials exposed in a mound that covers much of the floor of Spallanzani Crater.

    Location near: 58.3oS, 273.9oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  12. False Cross

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The asterism formed by the four stars δ and κ Velorum, and ɛ and ι Carinae, all of the second magnitude, which make up a cross of about 10°×6°. It is so named because it is sometimes mistaken for the Southern Cross (Crux) by observers unfamiliar with the southern sky. There is a superficial resemblance, but Crux is more compact (about 7°×5°) and comprises rather brighter stars. The two crosses ca...

  13. Polar Layers

    NASA Technical Reports Server (NTRS)

    2005-01-01

    12 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a slope upon which are exposed some of the layered materials that underlie the south polar cap of Mars. The layers are generally considered to be sediments--perhaps dust--that may have been cemented by water ice.

    Location near: 84.1oS, 343.9oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  14. Layered materials

    NASA Astrophysics Data System (ADS)

    Johnson, David; Clarke, Simon; Wiley, John; Koumoto, Kunihito

    2014-06-01

    Layered compounds, materials with a large anisotropy to their bonding, electrical and/or magnetic properties, have been important in the development of solid state chemistry, physics and engineering applications. Layered materials were the initial test bed where chemists developed intercalation chemistry that evolved into the field of topochemical reactions where researchers are able to perform sequential steps to arrive at kinetically stable products that cannot be directly prepared by other approaches. Physicists have used layered compounds to discover and understand novel phenomena made more apparent through reduced dimensionality. The discovery of charge and spin density waves and more recently the remarkable discovery in condensed matter physics of the two-dimensional topological insulating state were discovered in two-dimensional materials. The understanding developed in two-dimensional materials enabled subsequent extension of these and other phenomena into three-dimensional materials. Layered compounds have also been used in many technologies as engineers and scientists used their unique properties to solve challenging technical problems (low temperature ion conduction for batteries, easy shear planes for lubrication in vacuum, edge decorated catalyst sites for catalytic removal of sulfur from oil, etc). The articles that are published in this issue provide an excellent overview of the spectrum of activities that are being pursued, as well as an introduction to some of the most established achievements in the field. Clusters of papers discussing thermoelectric properties, electronic structure and transport properties, growth of single two-dimensional layers, intercalation and more extensive topochemical reactions and the interleaving of two structures to form new materials highlight the breadth of current research in this area. These papers will hopefully serve as a useful guideline for the interested reader to different important aspects in this field and

  15. Observations of the magnetopause current layer: Cases with no boundary layer and tests of recent models

    NASA Technical Reports Server (NTRS)

    Eastman, Timothy E.

    1995-01-01

    Evidence for the probable existence of magnetospheric boundary layers was first presented by Hones, et al. (1972), based on VELA satellite plasma observations (no magnetic field measurements were obtained). This magnetotail boundary layer is now known to be the tailward extension of the high-latitude boundary layer or plasma mantle (first uniquely identified using HEOS 2 plasma and field observations by Rosenbauer et al., 1975) and the low-latitude boundary layer (first uniquely identified using IMP 6 plasma and field observations by Eastman et al., 1976). The magnetospheric boundary layer is the region of magnetosheath-like plasma located Earthward of, but generally contiguous with the magnetopause. This boundary layer is typically identified by comparing low-energy (less than 10 keV) ion spectra across the magnetopause. Low-energy electron measurements are also useful for identifying the boundary layer because the shocked solar wind or magnetosheath has a characteristic spectral signature for electrons as well. However, there are magnetopause crossings where low-energy electrons might suggest a depletion layer outside the magnetopause even though the traditional field-rotation signature indicates that this same region is a boundary layer Earthward of the current layer. Our analyses avoided crossings which exhibit such ambiguities. Pristine magnetopause crossings are magnetopause crossings for which the current layer is well defined and for which there is no adjoining magnetospheric boundary layer as defined above. Although most magnetopause models to date apply to such crossings, few comparisons between such theory and observations of pristine magnetopause crossings have been made because most crossings have an associated magnetospheric boundary layer which significantly affects the applicable boundary conditions for the magnetopause current layer. Furthermore, almost no observational studies of magnetopause microstructure have been done even though key

  16. Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross ...

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

    Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross Bracing Joint, Vertical Cross Bracing End Detail - Ceylon Covered Bridge, Limberlost Park, spanning Wabash River at County Road 900 South, Geneva, Adams County, IN

  17. Double Layers in Astrophysics

    NASA Technical Reports Server (NTRS)

    Williams, Alton C. (Editor); Moorehead, Tauna W. (Editor)

    1987-01-01

    Topics addressed include: laboratory double layers; ion-acoustic double layers; pumping potential wells; ion phase-space vortices; weak double layers; electric fields and double layers in plasmas; auroral double layers; double layer formation in a plasma; beamed emission from gamma-ray burst source; double layers and extragalactic jets; and electric potential between plasma sheet clouds.

  18. Boundary layer transition studies

    NASA Technical Reports Server (NTRS)

    Watmuff, Jonathan H.

    1995-01-01

    A small-scale wind tunnel previously used for turbulent boundary layer experiments was modified for two sets of boundary layer transition studies. The first study concerns a laminar separation/turbulent reattachment. The pressure gradient and unit Reynolds number are the same as the fully turbulent flow of Spalart and Watmuff. Without the trip wire, a laminar layer asymptotes to a Falkner & Skan similarity solution in the FPG. Application of the APG causes the layer to separate and a highly turbulent and approximately 2D mean flow reattachment occurs downstream. In an effort to gain some physical insight into the flow processes a small impulsive disturbance was introduced at the C(sub p) minimum. The facility is totally automated and phase-averaged data are measured on a point-by-point basis using unprecedently large grids. The evolution of the disturbance has been tracked all the way into the reattachment region and beyond into the fully turbulent boundary layer. At first, the amplitude decays exponentially with streamwise distance in the APG region, where the layer remains attached, i.e. the layer is viscously stable. After separation, the rate of decay slows, and a point of minimum amplitude is reached where the contours of the wave packet exhibit dispersive characteristics. From this point, exponential growth of the amplitude of the disturbance is observed in the detached shear layer, i.e. the dominant instability mechanism is inviscid. A group of large-scale 3D vortex loops emerges in the vicinity of the reattachment. Remarkably, the second loop retains its identify far downstream in the turbulent boundary layer. The results provide a level of detail usually associated with CFD. Substantial modifications were made to the facility for the second study concerning disturbances generated by Suction Holes for laminar flow Control (LFC). The test section incorporates suction through interchangeable porous test surfaces. Detailed studies have been made using isolated

  19. Core layering

    NASA Astrophysics Data System (ADS)

    Jacobson, S. A.; Rubie, D. C.; Hernlund, J. W.; Morbidelli, A.

    2015-12-01

    We have created a planetary accretion and differentiation model that self-consistently builds and evolves Earth's core. From this model, we show that the core grows stably stratified as the result of rising metal-silicate equilibration temperatures and pressures, which increases the concentrations of light element impurities into each newer core addition. This stable stratification would naturally resist convection and frustrate the onset of a geodynamo, however, late giant impacts could mechanically mix the distinct accreted core layers creating large homogenous regions. Within these regions, a geodynamo may operate. From this model, we interpret the difference between the planetary magnetic fields of Earth and Venus as a difference in giant impact histories. Our planetary accretion model is a numerical N-body integration of the Grand Tack scenario [1]—the most successful terrestrial planet formation model to date [2,3]. Then, we take the accretion histories of Earth-like and Venus-like planets from this model and post-process the growth of each terrestrial planet according to a well-tested planetary differentiation model [4,5]. This model fits Earth's mantle by modifying the oxygen content of the pre-cursor planetesimals and embryos as well as the conditions of metal-silicate equilibration. Other non-volatile major, minor and trace elements included in the model are assumed to be in CI chondrite proportions. The results from this model across many simulated terrestrial planet growth histories are robust. If the kinetic energy delivered by larger impacts is neglected, the core of each planet grows with a strong stable stratification that would significantly impede convection. However, if giant impact mixing is very efficient or if the impact history delivers large impacts late, than the stable stratification can be removed. [1] Walsh et al. Nature 475 (2011) [2] O'Brien et al. Icarus 223 (2014) [3] Jacobson & Morbidelli PTRSA 372 (2014) [4] Rubie et al. EPSL 301

  20. Spray Layer-by-Layer Assembled Clay Composite Thin Films as Selective Layers in Reverse Osmosis Membranes.

    PubMed

    Kovacs, Jason R; Liu, Chaoyang; Hammond, Paula T

    2015-06-24

    Spray layer-by-layer assembled thin films containing laponite (LAP) clay exhibit effective salt barrier and water permeability properties when applied as selective layers in reverse osmosis (RO) membranes. Negatively charged LAP platelets were layered with poly(diallyldimethylammonium) (PDAC), poly(allylamine) (PAH), and poly(acrylic acid) (PAA) in bilayer and tetralayer film architectures to generate uniform films on the order of 100 nm thick that bridge a porous poly(ether sulfone) support to form novel RO membranes. Nanostructures were formed of clay layers intercalated in a polymeric matrix that introduced size-exclusion transport mechanisms into the selective layer. Thermal cross-linking of the polymeric matrix was used to increase the mechanical stability of the films and improve salt rejection by constraining swelling during operation. Maximum salt rejection of 89% was observed for the tetralayer film architecture, with an order of magnitude increase in water permeability compared to commercially available TFC-HR membranes. These clay composite thin films could serve as a high-flux alternative to current polymeric RO membranes for wastewater and brackish water treatment as well as potentially for forward osmosis applications. In general, we illustrate that by investigating the composite systems accessed using alternating layer-by-layer assembly in conjunction with complementary covalent cross-linking, it is possible to design thin film membranes with tunable transport properties for water purification applications.

  1. Disciplinary Crossings.

    PubMed

    Singh, Ilina

    2016-09-01

    Eighteen months ago, I left a permanent professorship in a generously interdisciplinary department of sociology and took an impermanent, lower-paying job at a university where I had to apply to something called the "Committee on Distinction" to retain the title of "Professor." Some people say, "That's what happens when Oxford calls." But it wasn't just that. It was the opportunity to engage in a groundbreaking experiment: to embed and integrate ethics within the Oxford Department of Psychiatry and Neuroscience. It's a dream job, for which I was willing to cross the disciplinary line into the medical sciences. In the United Kingdom, many bioethicists still work in departments outside science and medicine; similarly, those of us who work on neuroethics and psychiatric ethics tend to inhabit departments of philosophy, law, or sociology. I can report already that interdisciplinarity from this side feels and looks different. PMID:27649834

  2. Impinging jets in cross-flow

    NASA Astrophysics Data System (ADS)

    Knowles, K.; Bray, D.; Bailey, P. J.; Curtis, P.

    1992-02-01

    The present investigation of flowfields generated by the impingement of single and twin jets in cross-flows gives attention to the ground vortex position-defining parameters of cross-flow/nozzle velocities ratio, cross-flow boundary layer thickness, nozzle height, nozzle pressure ratio, vector angle, and nozzle splay (with both fixed and moving ground-planes). The results obtained indicate that the ground vortex moves away from the nozzle centerline as the ratio of cross-flow velocity to nozzle exit velocity is decreased. The positional rate of change, however, depends on other parameters. Self-similarity laws are proposed for the ground vortex and wall jet.

  3. Symmetry Breaking in Few Layer Graphene Films

    SciTech Connect

    Bostwick, A.; Ohta, T.; McChesney, J.L.; Emtsev, K.; Seyller,Th.; Horn, K.; Rotenberg, E.

    2007-05-25

    Recently, it was demonstrated that the quasiparticledynamics, the layer-dependent charge and potential, and the c-axisscreening coefficient could be extracted from measurements of thespectral function of few layer graphene films grown epitaxially on SiCusing angle-resolved photoemission spectroscopy (ARPES). In this articlewe review these findings, and present detailed methodology for extractingsuch parameters from ARPES. We also present detailed arguments againstthe possibility of an energy gap at the Dirac crossing ED.

  4. Jupiter's deep magnetotail boundary layer

    NASA Astrophysics Data System (ADS)

    Nicolaou, G.; McComas, D. J.; Bagenal, F.; Elliott, H. A.; Ebert, R. W.

    2015-06-01

    In 2007 the New Horizons (NH) spacecraft flew by Jupiter for a gravity assist en route to Pluto. After closest approach on day of year (DOY) 58, 2007, NH followed a tailward trajectory that provided a unique opportunity to explore the deep jovian magnetotail and the surrounding magnetosheath. After DOY 132, 16 magnetopause crossings were observed between 1654 and 2429 Jupiter radii (Rj) along the dusk flank tailward of the planet. In some cases the crossings were identified as rapid transitions from the magnetotail to the magnetosheath and vice versa. In other cases a boundary layer was observed just inside the magnetopause. Solar Wind Around Pluto (SWAP) is an instrument on board NH that obtained spectra of low energy ions during the flyby period. We use a forward model including the SWAP instrument response to derive plasma parameters (density, temperature and velocity) which best reproduce the observations. We also vary the plasma parameters in our model in order to fit the observations more accurately on occasions where the measurements exhibit significant variability. We compare the properties of the plasma in the boundary layer with those of the magnetosheath plasma derived in our earlier work. We attempt to estimate the magnetic field in the boundary layer assuming pressure balance between it and the magnetosheath. Finally, we investigate several possible scenarios to assess if magnetopause movement and structure could cause the variations seen in the data.

  5. Instability limits for spontaneous double layer formation

    SciTech Connect

    Carr, J. Jr.; Galante, M. E.; McCarren, D.; Scime, E. E.; Sears, S.; VanDervort, R. W.; Magee, R. M.; Reynolds, E.

    2013-11-15

    We present time-resolved measurements that demonstrate that large amplitude electrostatic instabilities appear in pulsed, expanding helicon plasmas at the same time as particularly strong double layers appear in the expansion region. A significant cross-correlation between the electrostatic fluctuations and fluctuations in the number of ions accelerated by the double layer electric field is observed. No correlation is observed between the electrostatic fluctuations and ions that have not passed through the double layer. These measurements confirm that the simultaneous appearance of the electrostatic fluctuations and the double layer is not simple coincidence. In fact, the accelerated ion population is responsible for the growth of the instability. The double layer strength, and therefore, the velocity of the accelerated ions, is limited by the appearance of the electrostatic instability.

  6. Subsurface Raman analysis of thin painted layers.

    PubMed

    Conti, Claudia; Colombo, Chiara; Realini, Marco; Zerbi, Giuseppe; Matousek, Pavel

    2014-01-01

    Here we present, for the first time, an extension of spatially offset Raman spectroscopy to thin (tens of micrometers thick), highly turbid stratified media such as those encountered in paintings. The method permits the non-destructive interrogation of painted layers in situations where conventional Raman microscopy is not applicable due to high turbidity of the top layer(s). The concept is demonstrated by recovering the pure Raman spectra of paint sub-layers that are completely obscured by paint over-layers. Potential application areas include the analysis of paintings in art preservation and restoration avoiding the cross-sectional analysis used currently with this type of samples. The technique also holds promise for the development as a non-destructive subsurface tool for in situ analysis using portable instruments.

  7. A POROUS, LAYERED HELIOPAUSE

    SciTech Connect

    Swisdak, M.; Drake, J. F.; Opher, M. E-mail: drake@umd.edu

    2013-09-01

    The picture of the heliopause (HP)-the boundary between the domains of the Sun and the local interstellar medium (LISM)-as a pristine interface with a large rotation in the magnetic field fails to describe recent Voyager 1 (V1) data. Magnetohydrodynamic (MHD) simulations of the global heliosphere reveal that the rotation angle of the magnetic field across the HP at V1 is small. Particle-in-cell simulations, based on cuts through the MHD model at V1's location, suggest that the sectored region of the heliosheath (HS) produces large-scale magnetic islands that reconnect with the interstellar magnetic field while mixing LISM and HS plasma. Cuts across the simulation reveal multiple, anti-correlated jumps in the number densities of LISM and HS particles, similar to those observed, at the magnetic separatrices. A model is presented, based on both the observations and simulations, of the HP as a porous, multi-layered structure threaded by magnetic fields. This model further suggests that contrary to the conclusions of recent papers, V1 has already crossed the HP.

  8. The research and realization of embedded GIS cross platform technique

    NASA Astrophysics Data System (ADS)

    Hu, Ze-ming; Li, Jing; Wang, Zhi-gang; Yue, Chun-sheng

    2008-10-01

    For the reason of embedded processors and embedded operating systems, and under the rapid motivation of application demands, cross platform technique has become a key point and developing direction in embedded GIS field, with the main purpose that once the application software has been written, it can run on multiple platforms with little modification or without modification. At present, cross platform technique includes three major aspects: middleware technique, Java Virtual Machine technique and abstract layer technique. Among these three techniques, the realization process of middleware has a close contact with the host operating system platform. Java Language has a good cross platform property relying on Java virtual machine, but code execution efficiency is poor. Abstract layer technique also has a good cross platform property, high code execution efficiency and better expansibility, but the interface definition and relative realization of abstract layer are more complicated. A fine software system architecture structure is important to ensure success for any software system. Obeying the hierarchical and modular design principle of cross platform software methods, after analyzing and comparing the advantages and disadvantages of the three cross platform techniques in details, abstract layer technique is adopted in this paper to design the software system architecture of embedded GIS cross platform, and describes the interior components of software developing platform layer. At present this cross platform architecture has been successfully realized on WinCE and Vxworks platforms, and the performance of operating map is very good.

  9. Cross-Layer Damage Assessment for Cyber Situational Awareness

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Jia, Xiaoqi; Zhang, Shengzhi; Xiong, Xi; Jhi, Yoon-Chan; Bai, Kun; Li, Jason

    Damage assessment plays a very important role in securing enterprise networks and systems. Gaining good awareness about the effects and impact of cyber attack actions would enable security officers to make the right cyber defense decisions and take the right cyber defense actions. A good number of damage assessment techniques have been proposed in the literature, but they typically focus on a single abstraction level (of the software system in concern). As a result, existing damage assessment techniques and tools are still very limited in satisfying the needs of comprehensive damage assessment which should not result in any “blind spots”.

  10. Burning Graphene Layer-by-Layer.

    PubMed

    Ermakov, Victor A; Alaferdov, Andrei V; Vaz, Alfredo R; Perim, Eric; Autreto, Pedro A S; Paupitz, Ricardo; Galvao, Douglas S; Moshkalev, Stanislav A

    2015-01-01

    Graphene, in single layer or multi-layer forms, holds great promise for future electronics and high-temperature applications. Resistance to oxidation, an important property for high-temperature applications, has not yet been extensively investigated. Controlled thinning of multi-layer graphene (MLG), e.g., by plasma or laser processing is another challenge, since the existing methods produce non-uniform thinning or introduce undesirable defects in the basal plane. We report here that heating to extremely high temperatures (exceeding 2000 K) and controllable layer-by-layer burning (thinning) can be achieved by low-power laser processing of suspended high-quality MLG in air in "cold-wall" reactor configuration. In contrast, localized laser heating of supported samples results in non-uniform graphene burning at much higher rates. Fully atomistic molecular dynamics simulations were also performed to reveal details of oxidation mechanisms leading to uniform layer-by-layer graphene gasification. The extraordinary resistance of MLG to oxidation paves the way to novel high-temperature applications as continuum light source or scaffolding material.

  11. Burning Graphene Layer-by-Layer.

    PubMed

    Ermakov, Victor A; Alaferdov, Andrei V; Vaz, Alfredo R; Perim, Eric; Autreto, Pedro A S; Paupitz, Ricardo; Galvao, Douglas S; Moshkalev, Stanislav A

    2015-01-01

    Graphene, in single layer or multi-layer forms, holds great promise for future electronics and high-temperature applications. Resistance to oxidation, an important property for high-temperature applications, has not yet been extensively investigated. Controlled thinning of multi-layer graphene (MLG), e.g., by plasma or laser processing is another challenge, since the existing methods produce non-uniform thinning or introduce undesirable defects in the basal plane. We report here that heating to extremely high temperatures (exceeding 2000 K) and controllable layer-by-layer burning (thinning) can be achieved by low-power laser processing of suspended high-quality MLG in air in "cold-wall" reactor configuration. In contrast, localized laser heating of supported samples results in non-uniform graphene burning at much higher rates. Fully atomistic molecular dynamics simulations were also performed to reveal details of oxidation mechanisms leading to uniform layer-by-layer graphene gasification. The extraordinary resistance of MLG to oxidation paves the way to novel high-temperature applications as continuum light source or scaffolding material. PMID:26100466

  12. Local Deplanation Of Double Reinforced Beam Cross Section Under Bending

    NASA Astrophysics Data System (ADS)

    Baltov, Anguel; Yanakieva, Ana

    2015-12-01

    Bending of beams, double reinforced by means of thin composite layers, is considered in the study. Approximate numerical solution is proposed, considering transitional boundary areas, where smooth quadratic transition of the elasticity modulus and deformations take place. Deplanation of the cross section is also accounted for in the areas. Their thickness is found equalizing the total stiffness of the cross section and the layer stiffness. Deplanation of the cross section of the transitional area is determined via the longitudinal deformation in the reinforcing layer, accounting for the equilibrium between the internal and the external moment, generated by the longitudinal stresses in the cross section. A numerical example is given as an illustration demonstrating model's plausibility. The model allows the design and the calculation of recycled concrete beams double reinforced by means of thin layers. The approach is in agreement with modern design of nearly zero energy buildings (NZEB).

  13. View of double floor boards with mortises cross beams, showing ...

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

    View of double floor boards with mortises cross beams, showing spikes and flooring nails (Lower board layer exposed) - Silas C. Read Sawmill, Outlet of Maxwell Lake near North Range Road, Fort Gordon, Richmond County, GA

  14. Modelling Layer parallel stylolites

    NASA Astrophysics Data System (ADS)

    Koehn, Daniel; Pataki Rood, Daisy; Beaudoin, Nicolas

    2016-04-01

    We modeled the geometrical roughening of mainly layer-dominated stylolites in order to understand their structural evolution, to present an advanced classification of stylolite shapes and to relate this classification to chemical compaction and stylolite sealing capabilities. Our simulations show that layer-dominated stylolites can grow in three distinct stages, an initial slow nucleation, a fast layer-pinning phase and a final freezing stage if the layer dissolves completely during growth. Dissolution of the pinning layer and thus destruction of the compaction tracking capabilities is a function of the background noise in the rock and the dissolution rate of the layer itself. Low background noise needs a slower dissolving layer for pinning to be successful but produces flatter teeth than higher background noise. We present an advanced classification based on our simulations and separate stylolites into four classes: rectangular layer type, seismogram pinning type, suture/sharp peak type and simple wave-like type.

  15. Mesoporous layer-by-layer ordered nanohybrids of layered double hydroxide and layered metal oxide: highly active visible light photocatalysts with improved chemical stability.

    PubMed

    Gunjakar, Jayavant L; Kim, Tae Woo; Kim, Hyo Na; Kim, In Young; Hwang, Seong-Ju

    2011-09-28

    Mesoporous layer-by-layer ordered nanohybrids highly active for visible light-induced O(2) generation are synthesized by self-assembly between oppositely charged 2D nanosheets of Zn-Cr-layered double hydroxide (Zn-Cr-LDH) and layered titanium oxide. The layer-by-layer ordering of two kinds of 2D nanosheets is evidenced by powder X-ray diffraction and cross-sectional high resolution-transmission electron microscopy. Upon the interstratification process, the original in-plane atomic arrangements and electronic structures of the component nanosheets remain intact. The obtained heterolayered nanohybrids show a strong absorption of visible light and a remarkably depressed photoluminescence signal, indicating an effective electronic coupling between the two component nanosheets. The self-assembly between 2D inorganic nanosheets leads to the formation of highly porous stacking structure, whose porosity is controllable by changing the ratio of layered titanate/Zn-Cr-LDH. The resultant heterolayered nanohybrids are fairly active for visible light-induced O(2) generation with a rate of ∼1.18 mmol h(-1) g(-1), which is higher than the O(2) production rate (∼0.67 mmol h(-1) g(-1)) by the pristine Zn-Cr-LDH material, that is, one of the most effective visible light photocatalysts for O(2) production, under the same experimental condition. This result highlights an excellent functionality of the Zn-Cr-LDH-layered titanate nanohybrids as efficient visible light active photocatalysts. Of prime interest is that the chemical stability of the Zn-Cr-LDH is significantly improved upon the hybridization, a result of the protection of the LDH lattice by highly stable titanate layer. The present findings clearly demonstrate that the layer-by-layer-ordered assembly between inorganic 2D nanosheets is quite effective not only in improving the photocatalytic activity of the component semiconductors but also in synthesizing novel porous LDH-based hybrid materials with improved chemical

  16. Microwave-cut silicon layer transfer

    SciTech Connect

    Thompson, D.C.; Alford, T.L.; Mayer, J.W.; Hochbauer, T.; Nastasi, M.; Lau, S.S.; Theodore, N. David; Henttinen, K.; Suni, Ilkka; Chu, Paul K.

    2005-11-28

    Microwave heating is used to initiate exfoliation of silicon layers in conjunction with the ion-cut process for transfer of silicon layers onto insulator or heterogeneous layered substrates. Samples were processed inside a 2.45 GHz, 1300 W cavity applicator microwave system for time durations as low as 12 s. This is a significant decrease in exfoliation incubation times. Sample temperatures measured by pyrometry were within previous published ranges. Rutherford backscattering spectrometry and cross-sectional transmission electron microscopy were used to determine layer thickness and crystallinity. Surface quality was measured by using atomic force microscopy. Hall measurements were used to characterize electrical properties as a function of postcut anneal time and temperature.

  17. Photonic layered media

    DOEpatents

    Fleming, James G.; Lin, Shawn-Yu

    2002-01-01

    A new class of structured dielectric media which exhibit significant photonic bandstructure has been invented. The new structures, called photonic layered media, are easy to fabricate using existing layer-by-layer growth techniques, and offer the ability to significantly extend our practical ability to tailor the properties of such optical materials.

  18. The structure of a three-dimensional turbulent boundary layer

    NASA Technical Reports Server (NTRS)

    Degani, A. T.; Smith, F. T.; Walker, J. D. A.

    1993-01-01

    The three-dimensional turbulent boundary layer is shown to have a self-consistent two-layer asymptotic structure in the limit of large Reynolds number. In a streamline coordinate system, the streamwise velocity distribution is similar to that in two-dimensional flows, having a defect-function form in the outer layer which is adjusted to zero at the wall through an inner wall layer. An asymptotic expansion accurate to two orders is required for the cross-stream velocity which is shown to exhibit a logarithmic form in the overlap region. The inner wall-layer flow is collateral to leading order but the influence of the pressure gradient, at large but finite Reynolds numbers, is not negligible and can cause substantial skewing of the velocity profile near the wall. Conditions under which the boundary layer achieves self-similarity and the governing set of ordinary differential equations for the outer layer are derived. The calculated solution of these equations is matched asymptotically to an inner wall-layer solution and the composite profiles so formed describe the flow throughout the entire boundary layer. The effects of Reynolds number and cross-stream pressure gradient on the crossstream velocity profile are discussed and it is shown that the location of the maximum cross-stream velocity is within the overlap region.

  19. Scintillator reflective layer coextrusion

    DOEpatents

    Yun, Jae-Chul; Para, Adam

    2001-01-01

    A polymeric scintillator has a reflective layer adhered to the exterior surface thereof. The reflective layer comprises a reflective pigment and an adhesive binder. The adhesive binder includes polymeric material from which the scintillator is formed. A method of forming the polymeric scintillator having a reflective layer adhered to the exterior surface thereof is also provided. The method includes the steps of (a) extruding an inner core member from a first amount of polymeric scintillator material, and (b) coextruding an outer reflective layer on the exterior surface of the inner core member. The outer reflective layer comprises a reflective pigment and a second amount of the polymeric scintillator material.

  20. Light scattering by cirrus cloud layers.

    NASA Technical Reports Server (NTRS)

    Liou, K.-N.

    1972-01-01

    The properties of the reflection, transmission, and absorption of the cirrus cloud layers are calculated under the assumption that the ice crystals in cirrus clouds may be approximated long circular cylinders randomly oriented in space. The phase function, the single scattering albedo, and the extinction cross section are obtained on the basis of Liou's (1972) calculations of light scattering by ice clouds in the visible and infrared. A modified two-stream approximation for radiative transfer is developed and is used to evaluate the radiative properties of the cirrus cloud layers.

  1. Piezoelectric Resonator with Two Layers

    NASA Technical Reports Server (NTRS)

    Stephanou, Philip J. (Inventor); Black, Justin P. (Inventor)

    2013-01-01

    A piezoelectric resonator device includes: a top electrode layer with a patterned structure, a top piezoelectric layer adjacent to the top layer, a middle metal layer adjacent to the top piezoelectric layer opposite the top layer, a bottom piezoelectric layer adjacent to the middle layer opposite the top piezoelectric layer, and a bottom electrode layer with a patterned structure and adjacent to the bottom piezoelectric layer opposite the middle layer. The top layer includes a first plurality of electrodes inter-digitated with a second plurality of electrodes. A first one of the electrodes in the top layer and a first one of the electrodes in the bottom layer are coupled to a first contact, and a second one of the electrodes in the top layer and a second one of the electrodes in the bottom layer are coupled to a second contact.

  2. Vortex boundary-layer interactions

    NASA Technical Reports Server (NTRS)

    Bradshaw, P.

    1986-01-01

    Parametric studies to identify a vortex generator were completed. Data acquisition in the first chosen configuration, in which a longitudinal vortex pair generated by an isolated delta wing starts to merge with a turbulent boundary layer on a flat plate fairly close to the leading edge is nearly completed. Work on a delta-wing/flat-plate combination, consisting of a flow visualization and hot wire measurements taken with a computer controlled traverse gear and data logging system were completed. Data taking and analysis have continued, and sample results for another cross stream plane are presented. Available data include all mean velocity components, second order mean products of turbulent fluctuations, and third order mean products. Implementation of a faster data logging system was accomplished.

  3. Layered plasma polymer composite membranes

    DOEpatents

    Babcock, W.C.

    1994-10-11

    Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is [>=]2 and is the number of selective layers. 2 figs.

  4. Toward evaluation of heat fluxes in the convective boundary layer

    SciTech Connect

    Sorbjan, Z.

    1995-05-01

    This article demonstrates that vertical profiles of the heat flux in the convective boundary layer can be diagnosed through an integration over height of the time change rates of observed potential temperature profiles. Moreover, the basic characteristics of the convective boundary layer, such as the mixed-layer height z{sub t}, the depth of the interfacial (entrainment) layer, and the heat flux zero-crossing height h{sub 0} can be uniquely evaluated based on a time evolution of potential temperature profiles in the lower atmosphere. 12 refs., 12 figs., 1 tab.

  5. Acquiring Peak Samples from Phytoplankton Thin Layers and Intermediate Nepheloid Layers by an Autonomous Underwater Vehicle with Adaptive Triggering

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; McEwen, R.; Ryan, J. P.; Bellingham, J. G.; Harvey, J.; Vrijenhoek, R.

    2010-12-01

    Phytoplankton thin layers (PTLs) affect many fundamental aspects of coastal ocean ecology including primary productivity, development of harmful algal blooms (HABs) and the survival and growth of zooplankton and fish larvae. Intermediate nepheloid layers (INLs) that contain suspended particulate matter transported from the bottom boundary layer of continental shelves and slopes also affect biogeochemistry and ecology of ocean margins. To better understand the impacts of these types of layers, we have developed an adaptive sampling method for an autonomous underwater vehicle (AUV) to detect a layer (adjusting detection parameters in situ), acquire water samples from peaks in the layer, and acquire control samples outside the layer. We have used the method in a number of field experiments with the AUV Dorado, which is equipped with ten water samplers (called "gulpers"). In real time, the algorithm tracks background levels of fluorescence and optical backscatter and the peaks' baseline to ensure that detection is tuned to the ambient conditions. The algorithm cross-checks fluorescence and backscatter signals to differentiate PTLs from INLs. To capture peak water samples with minimal delay, the algorithm exploits the AUV's sawtooth (i.e., yo-yo) trajectory: the vehicle crosses the detected layer twice in one yo-yo cycle. At the first crossing, it detects the layer's peak and saves its signal height. Sampling is triggered at the second crossing when the signal reaches the saved peak height plus meeting additional timing and depth conditions. The algorithm is also capable of triggering gulpers to acquire control samples outside the layer for comparison with ambient water. The sequence of peak and control samples can be set based on need. In recent AUV Dorado missions, the algorithm triggered the gulpers to acquire peak and control samples from INLs and PTLs in Monterey Bay. Zooplankton analysis of some peak samples showed very high concentrations of mussel and barnacle

  6. Undergraduate Cross Registration.

    ERIC Educational Resources Information Center

    Grupe, Fritz H.

    This report discusses various aspects of undergraduate cross-registration procedures, including the dimensions, values, roles and functions, basic assumptions, and facilitating and encouragment of cross-registration. Dimensions of cross-registration encompass financial exchange, eligibility, program limitations, type of grade and credit; extent of…

  7. Cross-Validation.

    ERIC Educational Resources Information Center

    Langmuir, Charles R.

    1954-01-01

    Cross-validation in relation to choosing the best tests and selecting the best items in tests is discussed. Cross-validation demonstrated whether a decision derived from one set of data is truly effective when this decision is applied to another independent, but relevant, sample of people. Cross-validation is particularly important after…

  8. Multiple density layered insulator

    DOEpatents

    Alger, Terry W.

    1994-01-01

    A multiple density layered insulator for use with a laser is disclosed wh provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation.

  9. Multiple density layered insulator

    DOEpatents

    Alger, T.W.

    1994-09-06

    A multiple density layered insulator for use with a laser is disclosed which provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation. 4 figs.

  10. The Atmospheric Boundary Layer

    ERIC Educational Resources Information Center

    Tennekes, Hendrik

    1974-01-01

    Discusses some important parameters of the boundary layer and effects of turbulence on the circulation and energy dissipation of the atmosphere. Indicates that boundary-layer research plays an important role in long-term forecasting and the study of air-pollution meteorology. (CC)

  11. Multiple layer insulation cover

    DOEpatents

    Farrell, James J.; Donohoe, Anthony J.

    1981-11-03

    A multiple layer insulation cover for preventing heat loss in, for example, a greenhouse, is disclosed. The cover is comprised of spaced layers of thin foil covered fabric separated from each other by air spaces. The spacing is accomplished by the inflation of spaced air bladders which are integrally formed in the cover and to which the layers of the cover are secured. The bladders are inflated after the cover has been deployed in its intended use to separate the layers of the foil material. The sizes of the material layers are selected to compensate for sagging across the width of the cover so that the desired spacing is uniformly maintained when the cover has been deployed. The bladders are deflated as the cover is stored thereby expediting the storage process and reducing the amount of storage space required.

  12. Cross-functional systems

    NASA Technical Reports Server (NTRS)

    Lee, Mark

    1991-01-01

    Many companies, including Xerox and Texas Instruments, are using cross functional systems to deal with the increasingly complex and competitive business environment. However, few firms within the aerospace industry appear to be aware of the significant benefits that cross functional systems can provide. Those benefits are examined and a flexible methodology is discussed that companies can use to identify and develop cross functional systems that will help improve organizational performance. In addition, some of the managerial issues are addressed that cross functional systems may raise and specific examples are used to explore networking's contributions to cross functional systems.

  13. On the origin of pure optical rotation in twisted-cross metamaterials.

    PubMed

    Barr, Lauren E; Díaz-Rubio, Ana; Tremain, Ben; Carbonell, Jorge; Sánchez-Dehesa, José; Hendry, Euan; Hibbins, Alastair P

    2016-07-26

    We present an experimental and computational study of the response of twisted-cross metamaterials that provide near dispersionless optical rotation across a broad band of frequencies from 19 GHz to 37 GHz. We compare two distinct geometries: firstly, a bilayer structure comprised of arrays of metallic crosses where the crosses in the second layer are twisted about the layer normal; and secondly where the second layer is replaced by the complementary to the original, i.e. an array of cross-shaped holes. Through numerical modelling we determine the origin of rotatory effects in these two structures. In both, pure optical rotation occurs in a frequency band between two transmission minima, where alignment of electric and magnetic dipole moments occurs. In the cross/cross metamaterial, the transmission minima occur at the symmetric and antisymmetric resonances of the coupled crosses. By contrast, in the cross/complementary-cross structure the transmission minima are associated with the dipole and quadrupole modes of the cross, the frequencies of which appear intrinsic to the cross layer alone. Hence the bandwidth of optical rotation is found to be relatively independent of layer separation.

  14. On the origin of pure optical rotation in twisted-cross metamaterials

    PubMed Central

    Barr, Lauren E.; Díaz-Rubio, Ana; Tremain, Ben; Carbonell, Jorge; Sánchez-Dehesa, José; Hendry, Euan; Hibbins, Alastair P.

    2016-01-01

    We present an experimental and computational study of the response of twisted-cross metamaterials that provide near dispersionless optical rotation across a broad band of frequencies from 19 GHz to 37 GHz. We compare two distinct geometries: firstly, a bilayer structure comprised of arrays of metallic crosses where the crosses in the second layer are twisted about the layer normal; and secondly where the second layer is replaced by the complementary to the original, i.e. an array of cross-shaped holes. Through numerical modelling we determine the origin of rotatory effects in these two structures. In both, pure optical rotation occurs in a frequency band between two transmission minima, where alignment of electric and magnetic dipole moments occurs. In the cross/cross metamaterial, the transmission minima occur at the symmetric and antisymmetric resonances of the coupled crosses. By contrast, in the cross/complementary-cross structure the transmission minima are associated with the dipole and quadrupole modes of the cross, the frequencies of which appear intrinsic to the cross layer alone. Hence the bandwidth of optical rotation is found to be relatively independent of layer separation. PMID:27457405

  15. 1. WEIDER'S CROSSING STONE HOUSE. WEIDER'S CROSSING WAS ONCE A ...

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

    1. WEIDER'S CROSSING STONE HOUSE. WEIDER'S CROSSING WAS ONCE A SIZABLE COMMUNITY. THIS IS ONE OF ONLY TWO HOUSES REMAINING MARKING WEIDER'S CROSSING. - Weider's Crossing Stone House, Weissport, Carbon County, PA

  16. Concentric layer ramjet fuel

    SciTech Connect

    Burdette, G.W.; Francis, J.P.

    1988-03-08

    This patent describes a solid fuel ramjet grain comprising concentric layers of solid ramjet fuel having a perforation therethrough along the center axis of the grain. The performation is connected to a combustion after-chamber. The solid ramjet fuel layers comprises a pure hydroxyl-terminated polybutadiene hydrocarbon fuel or a mixture of a hydroxyl-terminated polybutadiene hydrocarbon fuel and from about 5 to about 60 percent by weight of an additive to increase the fuel regression rate selected from the group consisting of magnesium, boron carbide, aluminum, and zirconium such that, when buried in the operation of the ramjet, each fuel layer produces a different level of thrust.

  17. Compliant layer chucking surface

    DOEpatents

    Blaedel, Kenneth L.; Spence, Paul A.; Thompson, Samuel L.

    2004-12-28

    A method and apparatus are described wherein a thin layer of complaint material is deposited on the surface of a chuck to mitigate the deformation that an entrapped particle might cause in the part, such as a mask or a wafer, that is clamped to the chuck. The harder particle will embed into the softer layer as the clamping pressure is applied. The material composing the thin layer could be a metal or a polymer for vacuum or electrostatic chucks. It may be deposited in various patterns to affect an interrupted surface, such as that of a "pin" chuck, thereby reducing the probability of entrapping a particle.

  18. Multi-layer coatings

    DOEpatents

    Maghsoodi, Sina; Brophy, Brenor L.; Abrams, Ze'ev R.; Gonsalves, Peter R.

    2016-06-28

    Disclosed herein are coating materials and methods for applying a top-layer coating that is durable, abrasion resistant, highly transparent, hydrophobic, low-friction, moisture-sealing, anti-soiling, and self-cleaning to an existing conventional high temperature anti-reflective coating. The top coat imparts superior durability performance and new properties to the under-laying conventional high temperature anti-reflective coating without reducing the anti-reflectiveness of the coating. Methods and data for optimizing the relative thickness of the under-layer high temperature anti-reflective coating and the top-layer thickness for optimizing optical performance are also disclosed.

  19. The Application of Layer Theory to Design: The Control Layer

    ERIC Educational Resources Information Center

    Gibbons, Andrew S.; Langton, Matthew B.

    2016-01-01

    A theory of design layers proposed by Gibbons ("An Architectural Approach to Instructional Design." Routledge, New York, 2014) asserts that each layer of an instructional design is related to a body of theory closely associated with the concerns of that particular layer. This study focuses on one layer, the control layer, examining…

  20. Covalent Fusion of layered Incompatible Gels in Immiscible Solvents

    NASA Astrophysics Data System (ADS)

    Biswas, Santidan; Singh, Awaneesh; Matyjaszewski, Krzysztof; Balazs, Anna C.

    We carry out dissipative particle dynamics (DPD) simulations to model a two layered stackable gel where the gels are incompatible and are present in immiscible solvent. The bottom layer of the gel is created first and then a solution of new initiators, monomers and cross-linkers is introduced on top of it. These components then undergo polymerization and form the second gel layer. We study all possible combinations of free radical polymerization (FRP) and atom transfer radical polymerization (ATRP) mechanisms with the two layers of the gel. For example, the bottom layer gel is created via ATRP, whereas the top layer gel follows FRP. Our focus is to do a systematic study of all these combinations and find out the factors responsible for combining two incompatible gels in immiscible solvents.

  1. Influence of curing temperature on properties of GPS adhesion promoter layers

    NASA Astrophysics Data System (ADS)

    Pavlovic, Elisabeth; Kent, Michael

    2005-03-01

    Adhesion promoter layers of glycidoxypropyltrimethoxysilane (GPS) were cured at various temperatures ranging from room temperature to 250 degC. The degree of cross-linking was investigated using infrared spectroscopy combined with deuterium/hydrogen exchange. The swelling of the GPS layers by solvent (d-nitrobenzene) and water was investigated using x-ray and neutron reflection. Curing temperatures higher than 90 degC produced highly cross-linked GPS layers, with a loss of epoxy groups. A complete cross-linking was reached at a curing temperature of 250 degC. We expect that the cross-link density of the GPS layer, and subsequently its swelling ability, as well as its remaining epoxy functionality should have a major impact on the fracture energy of the interface with epoxy. These questions are investigated by asymmetric double cantilever beam fracture experiments on interfaces between GPS layers cured at these different temperatures on silicon wafers and epoxy resin beams.

  2. Terby's Layered Rocks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    14 March 2004 Layered rock outcrops are common all across Mars, and the Mars rover, Opportunity, has recently investigated some layered rocks in Meridiani Planum. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered sedimentary rocks in northern Terby Crater, located just north of the giant Hellas Basin near 27.5oS, 285.8oW. Hundreds of layers are exposed in a deposit several kilometers thick within Terby. A history of events that shaped the northern Hellas region is recorded in these rocks, just waiting for a person or robot to investigate. The picture covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the left.

  3. North Polar Layers, Mars

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This view shows the basal layers of Mars' north polar layered deposits. The floor of Chasma Boreale is at the bottom of the image. This is a sub-image of a larger view imaged by the High Resolution Imaging Science Experiment (HiRISE) on NASA's Mars Reconnaissance Orbiter on Oct. 1, 2006. The resolution is 64 centimeters (25 inches) per pixel, and the scene is 568 meters (621 yards) wide.

  4. Boundary Layer Relaminarization Device

    NASA Technical Reports Server (NTRS)

    Creel, Theodore R. (Inventor)

    1993-01-01

    Relamination of a boundary layer formed in supersonic flow over the leading edge of a swept airfoil is accomplished using at least one band, especially a quadrangular band, and most preferably a square band. Each band conforms to the leading edge and the upper and lower surfaces of the airfoil as an integral part thereof and extends perpendicularly from the leading edge. Each band has a height of about two times the thickness of the maximum expected boundary layer.

  5. Structured luminescence conversion layer

    DOEpatents

    Berben, Dirk; Antoniadis, Homer; Jermann, Frank; Krummacher, Benjamin Claus; Von Malm, Norwin; Zachau, Martin

    2012-12-11

    An apparatus device such as a light source is disclosed which has an OLED device and a structured luminescence conversion layer deposited on the substrate or transparent electrode of said OLED device and on the exterior of said OLED device. The structured luminescence conversion layer contains regions such as color-changing and non-color-changing regions with particular shapes arranged in a particular pattern.

  6. Cross resonant optical antenna.

    PubMed

    Biagioni, P; Huang, J S; Duò, L; Finazzi, M; Hecht, B

    2009-06-26

    We propose a novel cross resonant optical antenna consisting of two perpendicular nanosized gold dipole antennas with a common feed gap. We demonstrate that the cross antenna is able to convert propagating fields of any polarization state into correspondingly polarized, localized, and enhanced fields and vice versa. The cross antenna structure therefore opens the road towards the control of light-matter interactions based on polarized light as well as the analysis of polarized fields on the nanometer scale.

  7. Modification of layered atelocollagen: enzymatic degradation and cytotoxicity evaluation.

    PubMed

    Vizárová, K; Bakos, D; Rehákova, M; Petríkova, M; Panáková, E; Koller, J

    1995-11-01

    Two kinds of layered atelocollagen materials cross-linked with hexamethylene diisocyanate (HMDIC), starch dialdehyde and glyoxal were enzymatically treated by bacterial collagenase. Evaluating collagenase digestion assay for these material showed progressive differences, particularly in the group of samples cross-linked with HMDIC. This should offer the possibility of programmed enzymatic degradation. These materials may be toxicologically acceptable as proven by the short-term test used for cytotoxicity evaluation.

  8. Bioinspired layered materials with superior mechanical performance.

    PubMed

    Cheng, Qunfeng; Jiang, Lei; Tang, Zhiyong

    2014-04-15

    Nature has inspired researchers to construct structures with ordered layers as candidates for new materials with high mechanical performance. As a prominent example, nacre, also known as mother of pearl, consists of a combination of inorganic plates (aragonite calcium carbonate, 95% by volume) and organic macromolecules (elastic biopolymer, 5% by volume) and shows a unique combination of strength and toughness. Investigations of its structure reveal that the hexagonal platelets of calcium carbonate and the amorphous biopolymer are alternatively assembled into the orderly layered structure. The delicate interface between the calcium carbonate and the biopolymer is well defined. Both the building blocks that make up these assembled layers and the interfaces between the inorganic and organic components contribute to the excellent mechanical property of natural nacre. In this Account, we summarize recent research from our group and from others on the design of bioinspired materials composed by layering various primitive materials. We focus particular attention on nanoscale carbon materials. Using several examples, we describe how the use of different combinations of layered materials leads to particular properties. Flattened double-walled carbon nanotubes (FDWCNTs) covalently cross-linked in a thermoset three-dimensional (3D) network produced the materials with the highest strength. The stiffest layered materials were generated from borate orthoester covalent bonding between adjacent graphene oxide (GO) nanosheets, and the toughest layered materials were fabricated with Al2O3 platelets and chitosan via hydrogen bonding. These new building blocks, such as FDWCNTs and GO, and the replication of the elaborate micro-/nanoscale interface of natural nacre have provided many options for developing new high performance artificial materials. The interface designs for bioinspired layered materials are generally categorized into (1) hydrogen bonding, (2) ionic bonding, and (3

  9. Tests on Double Layer Metalization

    NASA Technical Reports Server (NTRS)

    Woo, D. S.

    1983-01-01

    28 page report describes experiments in fabrication of integrated circuits with double-layer metalization. Double-layer metalization requires much less silicon "real estate" and allows more flexibility in placement of circuit elements than does single-layer metalization.

  10. Cross-Generational Storytelling

    ERIC Educational Resources Information Center

    Smith, Cindy; Thurston, Judy Kay

    2007-01-01

    What happens when you combine senior citizens, pre-service art teachers, and elementary students? Cross-generational connections based on sharing memories, ideas, skills, laughter, tears, and creativity. The authors describe the cross-generational book exchange project. This project was initiated when a group of Central Michigan University (CMU)…

  11. South Polar Layers

    NASA Technical Reports Server (NTRS)

    2004-01-01

    2 July 2004 Beneath the ice caps of both martian poles lies extensive deposits of layered material. Whether the material includes ice is unknown. In the north polar region, some of the layers contain dark sand, others may consist of dust cemented by ice. The south polar layers are a little bit more challenging to understand. In most places, they have been covered by thin mantles of debris that mask the true nature of the layered material. This is the case, even in the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shown here. South polar layers were eroded to provide this spectacular view, but later the materials were almost uniformly covered with a material that, when the image is viewed at full resolution (click on image, above), has become cracked. This picture is located near 82.0oS, 72.4oW, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the upper left.

  12. Layered electrode for electrochemical cells

    DOEpatents

    Swathirajan, Swathy; Mikhail, Youssef M.

    2001-01-01

    There is provided an electrode structure comprising a current collector sheet and first and second layers of electrode material. Together, the layers improve catalyst utilization and water management.

  13. Cross-Shelf Exchange.

    PubMed

    Brink, K H

    2016-01-01

    Cross-shelf exchange dominates the pathways and rates by which nutrients, biota, and materials on the continental shelf are delivered and removed. This follows because cross-shelf gradients of most properties are usually far greater than those in the alongshore direction. The resulting transports are limited by Earth's rotation, which inhibits flow from crossing isobaths. Thus, cross-shelf flows are generally weak compared with alongshore flows, and this leads to interesting observational issues. Cross-shelf flows are enabled by turbulent mixing processes, nonlinear processes (such as momentum advection), and time dependence. Thus, there is a wide range of possible effects that can allow these critical transports, and different natural settings are often governed by different combinations of processes. This review discusses examples of representative transport mechanisms and explores possible observational and theoretical paths to future progress.

  14. Cross-Shelf Exchange.

    PubMed

    Brink, K H

    2016-01-01

    Cross-shelf exchange dominates the pathways and rates by which nutrients, biota, and materials on the continental shelf are delivered and removed. This follows because cross-shelf gradients of most properties are usually far greater than those in the alongshore direction. The resulting transports are limited by Earth's rotation, which inhibits flow from crossing isobaths. Thus, cross-shelf flows are generally weak compared with alongshore flows, and this leads to interesting observational issues. Cross-shelf flows are enabled by turbulent mixing processes, nonlinear processes (such as momentum advection), and time dependence. Thus, there is a wide range of possible effects that can allow these critical transports, and different natural settings are often governed by different combinations of processes. This review discusses examples of representative transport mechanisms and explores possible observational and theoretical paths to future progress. PMID:26747520

  15. Phantom Crossing DGP Gravity

    SciTech Connect

    Hirano, Koichi; Komiya, Zen

    2010-08-12

    We propose a phantom crossing Dvali-Gabadadze-Porrati (DGP) model. In our model, the effective equation of state of the DGP gravity crosses the phantom divide line. We demonstrate crossing of the phantom divide does not occur within the framework of the original DGP model or the DGP model developed by Dvali and Turner. By extending their model, we construct a model that realizes crossing of the phantom divide. DGP models can account for late-time acceleration of the universe without dark energy. Phantom Crossing DGP model is more compatible with recent observational data from Type Ia Supernovae (SNIa), Cosmic Microwave Background (CMB) anisotropies, and Baryon Acoustic Oscillations (BAO) than the original DGP model or the DGP model developed by Dvali and Turner.

  16. Evaluation of dry etching and defect repair of EUVL mask absorber layer

    NASA Astrophysics Data System (ADS)

    Abe, Tsukasa; Nishiguchi, Masaharu; Amano, Tsuyoshi; Motonaga, Toshiaki; Sasaki, Shiho; Mohri, Hiroshi; Hayashi, Naoya; Tanaka, Yuusuke; Nishiyama, Iwao

    2004-12-01

    EUVL mask process of absorber layer, buffer layer dry etching and defect repair were evaluated. TaGeN and Cr were selected for absorber layer and buffer layer, respectively. These absorber layer and buffer layer were coated on 6025 Qz substrate. Two dry etching processes were evaluated for absorber layer etching. One is CF4 plasma process and the other is Cl2 plasma process. Etch bias uniformity, selectivity, cross section profile and resist damage were evaluated for each process. Disadvantage of CF4 plasma process is low resist selectivity and Cl2 plasma process is low Cr selectivity. CF4 plasma process caused small absorber layer damage on isolate line and Cl2 plasma process caused Cr buffer layer damage. To minimize these damages overetch time was evaluated. Buffer layer process was also evaluated. Buffer layer process causes capping layer damage. Therefore, etching time was optimized. FIB-GAE and AFM machining were applied for absorber layer repair test. XeF2 gas was used for FIB-GAE. Good selectivity between absorber layer and buffer layer was obtained using XeF2 gas. However, XeF2 gas causes side etching of TaGeN layer. AFM machining repair technique was demonstrated for TaGeN layer repair.

  17. Layers in Terby Crater

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-407, 30 June 2003

    Whether on Earth or Mars, sedimentary rocks provide a record of past environments. Of course, it is difficult to read that record without being able to visit the site. However, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) has revealed hundreds of locales on Mars at which sedimentary rocks are exposed at the surface. Terby Crater exhibits hundreds of layers of similar thickness and physical properties--some have speculated these may be the record of an ancient lake or sea. This MOC image shows some of the layer outcrops in Terby Crater. Fans of debris have eroded from the steep, layered slopes in some places. This picture covers an area 3 km (1.9 mi) wide near 27.5oS, 285.7oW. The image is illuminated from the upper left and was obtained in June 2003.

  18. Frosty North Polar Layers

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-349, 3 May 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is a springtime view of frost-covered layers revealed by an eroded scarp in the martian north polar cap. The layers are thought to consist of a mixture of dust, ice, and possibly sand. Some layers are known to be a source for dark sand that occurs in nearby dunes. During the summer, this surface would be considerably darker because most of the bright frost sublimes away during the spring season. The picture covers an area about 3 km (1.9 mi) wide near 85.2oN, 4.4oW. Sunlight illuminates the scene from the lower left.

  19. North Polar Layers

    NASA Technical Reports Server (NTRS)

    2004-01-01

    3 December 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an exposure of finely-detailed layers in the martian north polar region. The polar ice cap, which is made up of frozen water (whereas the south polar cap is mostly frozen carbon dioxide), is underlain by a thick sequence of layers. Some have speculated that these layers may record the history of changes in martian climate during the past few hundreds of millions of years. This picture is located near 86.0oN, 30.2oW, and covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.

  20. Boundary layer simulator improvement

    NASA Technical Reports Server (NTRS)

    Praharaj, Sarat C.; Schmitz, Craig P.; Nouri, Joseph A.

    1989-01-01

    Boundary Layer Integral Matrix Procedure (BLIMPJ) has been identified by the propulsion community as the rigorous boundary layer program in connection with the existing JANNAF reference programs. The improvements made to BLIMPJ and described herein have potential applications in the design of the future Orbit Transfer Vehicle engines. The turbulence model is validated to include the effects of wall roughness and a way is devised to treat multiple smooth-rough surfaces. A prediction of relaminarization regions is examined as is the combined effects of wall cooling and surface roughness on relaminarization. A turbulence model to represent the effects of constant condensed phase loading is given. A procedure is described for thrust decrement calculation in thick boundary layers by coupling the T-D Kinetics Program and BLIMPJ and a way is provided for thrust loss optimization. Potential experimental studies in rocket nozzles are identified along with the required instrumentation to provide accurate measurements in support of the presented new analytical models.

  1. Layered Systems Engineering Engines

    NASA Technical Reports Server (NTRS)

    Breidenthal, Julian C.; Overman, Marvin J.

    2009-01-01

    A notation is described for depicting the relationships between multiple, contemporaneous systems engineering efforts undertaken within a multi-layer system-of-systems hierarchy. We combined the concepts of remoteness of activity from the end customer, depiction of activity on a timeline, and data flow to create a new kind of diagram which we call a "Layered Vee Diagram." This notation is an advance over previous notations because it is able to be simultaneously precise about activity, level of granularity, product exchanges, and timing; these advances provide systems engineering managers a significantly improved ability to express and understand the relationships between many systems engineering efforts. Using the new notation, we obtain a key insight into the relationship between project duration and the strategy selected for chaining the systems engineering effort between layers, as well as insights into the costs, opportunities, and risks associated with alternate chaining strategies.

  2. Prediction of 3-D boundary layer in the curved inlets

    NASA Astrophysics Data System (ADS)

    Xing, Zongwen; Wang, Jianmin

    1992-06-01

    A prediction method for 3D compressible turbulent boundary layers in curved inlets is investigated. 3D boundary layer integral equations in nonorthogonal curvilinear coordinate system are used and solved by lag-entrainment method with an introduced 3D entrainment coefficient equation. During numerical calculation, the prediction corrector method is employed. With the cubic spline function, the interpolation and differentiation accuracy and smoothness of discrete data is ensured. The developed program may be operated on a personal computer. The influence of cross flow on boundary layer development is clearly shown by the calculated results. The calculated pressure recovery of the inlet is in good agreement with experiment data.

  3. Layers and Streaks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    6 December 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an outcrop of light-toned layered rock and a plethora of dark streaks on the floor of a crater in southern Noachis Terra. The streaks were created by dozens of dust devils which disrupted and perhaps removed some of the thin layer of dust that coats the surface. This view is located near 55.5oS, 333.4oW. The scene is illuminated by sunlight from the lower right. The 500 meter scale bar is approximately 547 yards long.

  4. North Polar Layer Exposure

    NASA Technical Reports Server (NTRS)

    2004-01-01

    20 November 2004 Both the north and south polar ice caps overlie a thick accumulation of layered material. For more than three decades, these deposits have been assumed to consist of a mixture of dust and ice. This October 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the north polar layers exposed on a slope located near 79.1oN, 348.4oW. The image covers an area approximately 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  5. Sedimentary Rock Layers

    NASA Technical Reports Server (NTRS)

    2004-01-01

    27 January 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layers of sedimentary rock in a crater in western Arabia Terra. Layered rock records the history of a place, but an orbiter image alone cannot tell the entire story. These materials record some past episodes of deposition of fine-grained material in an impact crater that is much larger than the image shown here. The picture is located near 3.4oN, 358.7oW, and covers an area 3 km (1.9 mi.) wide. Sunlight illuminates the scene from the lower left.

  6. Solution processed organic light-emitting diodes using the plasma cross-linking technology

    NASA Astrophysics Data System (ADS)

    He, Kongduo; Liu, Yang; Gong, Junyi; Zeng, Pan; Kong, Xun; Yang, Xilu; Yang, Cheng; Yu, Yan; Liang, Rongqing; Ou, Qiongrong

    2016-09-01

    Solution processed multilayer organic light-emitting diodes (OLEDs) present challenges, especially regarding dissolution of the first layer during deposition of a second layer. In this work, we first demonstrated a plasma cross-linking technology to produce a solution processed OLED. The surfaces of organic films can be cross-linked after mixed acetylene and Ar plasma treatment for several tens of seconds and resist corrosion of organic solvent. The film thickness and surface morphology of emissive layers (EMLs) with plasma treatment and subsequently spin-rinsed with chlorobenzene are nearly unchanged. The solution processed triple-layer OLED is successfully fabricated and the current efficiency increases 50% than that of the double-layer OLED. Fluorescent characteristics of EMLs are also observed to investigate factors influencing the efficiency of the triple-layer OLED. Plasma cross-linking technology may open up a new pathway towards fabrication of all-solution processed multilayer OLEDs and other soft electronic devices.

  7. Measurements of a separating turbulent boundary layer

    NASA Astrophysics Data System (ADS)

    Simpson, R. L.; Chew, Y. T.; Shivaprasad, B. G.

    1980-04-01

    The directionally sensitive laser anemometer now provides the ability to accurately measure instantaneous flow direction and magnitude. The experimental results are concerned with a nominally two dimensional separating turbulent boundary layer for an airfoil type flow in which the flow was accelerated and then decelerated until separation. Upstream of separation single and cross wire hot wire anemometer measurements are also presented. Measurements obtained in the separated zone with a directionally sensitive laser anemometer system are presented. Results lead to significant conclusions about the nature of the separated flow when the thickness of the backflow region is small as compared with the shear laer thickness. The backflow is controlled by the large scale outer region flow. The small mean backflow does not come from far downstream, but appears to be supplied intermittently by large scale structures as they pass through the separated flow. Downstream of fully developed separation, the mean backflow appears to be divided into three layers.

  8. Layered pavement systems

    NASA Astrophysics Data System (ADS)

    Numerous aspects of the mechanical and structural response of layered pavement systems are discussed. Subgrade moduli for soil that exhibits nonlinear behavior are predicted. The use of a pressure meter test to predict modulus is discussed. Load equivalency factors of triaxial loading for flexible pavements is discussed, as well as a constitutive equation for the permanent strain of sand subjected to cyclic loading.

  9. Layer-Cake Earth

    ERIC Educational Resources Information Center

    Tedford, Rebecca; Warny, Sophie

    2006-01-01

    In this article, the authors offer a safe, fun, effective way to introduce geology concepts to elementary school children of all ages: "coring" layer cakes. This activity introduces the concepts and challenges that geologists face and at the same time strengthens students' inferential, observational, and problem-solving skills. It also addresses…

  10. Martian Meteor Ionization Layers

    NASA Technical Reports Server (NTRS)

    Grebowsky, J. M.; Pesnell, W. D.

    1999-01-01

    Small interplanetary grains bombard Mars, like all the solar system planets, and, like all the planets with atmospheres, meteoric ion and atom layers form in the upper atmosphere. We have developed a comprehensive one-dimensional model of the Martian meteoric ionization layer including a full chemical scheme. A persistent layer of magnesium ions should exist around an altitude of 70 km. Unlike the terrestrial case, where the metallic ions are formed via charge-exchange with the ambient ions, Mg(+) in the Martian atmosphere is produced by photoionization. Nevertheless, the predicted metal layer peak densities for Earth and Mars are similar. Diffusion solutions, such as those presented here, should be a good approximation of the metallic ions in regions where the magnetic field is negligible and may provide a significant contribution to the nightside ionosphere. The low ultraviolet absorption of the Martian atmosphere may make Mars an excellent laboratory in which to study meteoric ablation. Resonance lines not seen in the spectra of terrestrial meteors may be visible to a surface observatory in the Martian highlands.

  11. Teaching the Double Layer.

    ERIC Educational Resources Information Center

    Bockris, J. O'M.

    1983-01-01

    Suggests various methods for teaching the double layer in electrochemistry courses. Topics addressed include measuring change in absolute potential difference (PD) at interphase, conventional electrode potential scale, analyzing absolute PD, metal-metal and overlap electron PDs, accumulation of material at interphase, thermodynamics of electrified…

  12. MITRE sensor layer prototype

    NASA Astrophysics Data System (ADS)

    Duff, Francis; McGarry, Donald; Zasada, David; Foote, Scott

    2009-05-01

    The MITRE Sensor Layer Prototype is an initial design effort to enable every sensor to help create new capabilities through collaborative data sharing. By making both upstream (raw) and downstream (processed) sensor data visible, users can access the specific level, type, and quantities of data needed to create new data products that were never anticipated by the original designers of the individual sensors. The major characteristic that sets sensor data services apart from typical enterprise services is the volume (on the order of multiple terabytes) of raw data that can be generated by most sensors. Traditional tightly coupled processing approaches extract pre-determined information from the incoming raw sensor data, format it, and send it to predetermined users. The community is rapidly reaching the conclusion that tightly coupled sensor processing loses too much potentially critical information.1 Hence upstream (raw and partially processed) data must be extracted, rapidly archived, and advertised to the enterprise for unanticipated uses. The authors believe layered sensing net-centric integration can be achieved through a standardize-encapsulate-syndicateaggregate- manipulate-process paradigm. The Sensor Layer Prototype's technical approach focuses on implementing this proof of concept framework to make sensor data visible, accessible and useful to the enterprise. To achieve this, a "raw" data tap between physical transducers associated with sensor arrays and the embedded sensor signal processing hardware and software has been exploited. Second, we encapsulate and expose both raw and partially processed data to the enterprise within the context of a service-oriented architecture. Third, we advertise the presence of multiple types, and multiple layers of data through geographic-enabled Really Simple Syndication (GeoRSS) services. These GeoRSS feeds are aggregated, manipulated, and filtered by a feed aggregator. After filtering these feeds to bring just the type

  13. Surface Roughness and Dislocation Distribution in Compositionally Graded Relaxed SiGe Buffer Layer with Inserted Strained Si Layers

    NASA Astrophysics Data System (ADS)

    Yoon, Tae-Sik

    2005-03-01

    We report the experimental investigation of surface roughness and dislocation distribution of 1 μm-thick, compositionally graded, relaxed SiGe buffer layer with a final Ge surface content of 30%. Tensile-strained Si layers are inserted at various locations in the graded buffer during SiGe epitaxial growths. Slight reduction in surface roughness from about 10.3 nm to about 7.8 nm by inserting two 20 nm thick tensile-strained Si layers followed by SiGe growths. It turns out that majority of the residual surface roughness is developed during the SiGe growths on top of the topmost strain Si layer. The surface immediately after the growth of tensile strained Si is very flat with about 1.1 nm RMS roughness and without crosshatch morphology. Cross-sectional TEM shows clear signs of increased interaction between dislocation half-loops at the top surface of the strained Si layers. Our observation shows that although thin Si layers under tensile-strain are effective in reducing cross-hatch, they could in the meantime impede dislocation propagation leading to higher threading dislocation density. Considerations for an optimized scheme exploiting the flattening function of tensile-strained layers will be discussed.

  14. Flow visualization of turbulent boundary layer structure

    NASA Astrophysics Data System (ADS)

    Head, M. R.; Bandyopadhyay, P.

    1980-01-01

    The results from flow visualization experiments performed using an argon-ion laser to illuminate longitudinal and transverse sections of the smoke filled boundary layer in zero pressure gradient are discussed. Most of the experiments were confined to the range 600 Re sub theta 10,000. Results indicate that the boundary layer consists almost exclusively of vortex loops or hairpins, some of which may extend through the complete boundary layer thickness and all of which are inclined at a more or less constant characteristic angle of approximately 45 deg to the wall. Since the cross-stream dimensions of the hairpins appear to scale roughly with the wall variables U sub tau and nu, while their length is limited only by the boundary layer thickness, there are very large scale effects on the turbulence structure. At high Reynolds numbers (Re sub theta = 10,000) there is little evidence of large-scale coherent motions, other than a slow overturning of random agglomerations of the hairpins just mentioned.

  15. A microwave scattering model for layered vegetation

    NASA Technical Reports Server (NTRS)

    Karam, Mostafa A.; Fung, Adrian K.; Lang, Roger H.; Chauhan, Narinder S.

    1992-01-01

    A microwave scattering model was developed for layered vegetation based on an iterative solution of the radiative transfer equation up to the second order to account for multiple scattering within the canopy and between the ground and the canopy. The model is designed to operate over a wide frequency range for both deciduous and coniferous forest and to account for the branch size distribution, leaf orientation distribution, and branch orientation distribution for each size. The canopy is modeled as a two-layered medium above a rough interface. The upper layer is the crown containing leaves, stems, and branches. The lower layer is the trunk region modeled as randomly positioned cylinders with a preferred orientation distribution above an irregular soil surface. Comparisons of this model with measurements from deciduous and coniferous forests show good agreements at several frequencies for both like and cross polarizations. Major features of the model needed to realize the agreement include allowance for: (1) branch size distribution, (2) second-order effects, and (3) tree component models valid over a wide range of frequencies.

  16. Crossing species boundaries.

    PubMed

    Robert, Jason Scott; Baylis, Françoise

    2003-01-01

    This paper critically examines the biology of species identity and the morality of crossing species boundaries in the context of emerging research that involves combining human and nonhuman animals at the genetic or cellular level. We begin with the notion of species identity, particularly focusing on the ostensible fixity of species boundaries, and we explore the general biological and philosophical problem of defining species. Against this backdrop, we survey and criticize earlier attempts to forbid crossing species boundaries in the creation of novel beings. We do not attempt to establish the immorality of crossing species boundaries, but we conclude with some thoughts about such crossings, alluding to the notion of moral confusion regarding social and ethical obligations to novel interspecies beings.

  17. Cross-Country Skiing.

    ERIC Educational Resources Information Center

    Arnold, Guy E.

    1980-01-01

    The cross-country ski program offered at Clarkson College in New York is described, including a brief outline of the course, necessary equipment, and suggestions for developing a similar course at other campuses. (JMF)

  18. Avoided Crossing and Synchronization

    NASA Astrophysics Data System (ADS)

    Sekii, T.; Shibahashi, H.

    2013-12-01

    We examine avoided crossing of stellar pulsations in the nonlinear regime, where synchronization may occur, based on a simple model of weakly coupled van der Pol oscillators with close frequencies. For this simple case, avoided crossing is unaffected in the sense that there is a frequency difference between the symmetric and antisymmetric modes, but as a result of synchronization, unlike the linear oscillations case, the system can vibrate in only one of the modes.

  19. Peeling Back the Layers

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA's Mars Exploration Rover Spirit took this panoramic camera image of the rock target named 'Mazatzal' on sol 77 (March 22, 2004). It is a close-up look at the rock face and the targets that will be brushed and ground by the rock abrasion tool in upcoming sols.

    Mazatzal, like most rocks on Earth and Mars, has layers of material near its surface that provide clues about the history of the rock. Scientists believe that the top layer of Mazatzal is actually a coating of dust and possibly even salts. Under this light coating may be a more solid portion of the rock that has been chemically altered by weathering. Past this layer is the unaltered rock, which may give scientists the best information about how Mazatzal was formed.

    Because each layer reveals information about the formation and subsequent history of Mazatzal, it is important that scientists get a look at each of them. For this reason, they have developed a multi-part strategy to use the rock abrasion tool to systematically peel back Mazatzal's layers and analyze what's underneath with the rover's microscopic imager, and its Moessbauer and alpha particle X-ray spectrometers.

    The strategy began on sol 77 when scientists used the microscopic imager to get a closer look at targets on Mazatzal named 'New York,' 'Illinois' and 'Arizona.' These rock areas were targeted because they posed the best opportunity for successfully using the rock abrasion tool; Arizona also allowed for a close-up look at a range of tones. On sol 78, Spirit's rock abrasion tool will do a light brushing on the Illinois target to preserve some of the surface layers. Then, a brushing of the New York target should remove the top coating of any dust and salts and perhaps reveal the chemically altered rock underneath. Finally, on sol 79, the rock abrasion tool will be commanded to grind into the New York target, which will give scientists the best chance of observing Mazatzal's interior.

    The Mazatzal targets were named

  20. Interpretive 2-D treatment of scrape-off-layer plasmas

    SciTech Connect

    Umansky, M.; Allen, A.; Daughton, W.

    1996-12-31

    The width of the scrape-off-layer in a tokamak is determined by cross field transport. In Alcator C-mod the plasma parameters in the scrape-off-layer are measured at upstream and divertor plate locations. We solve a 2-D scrape-off-layer heat conduction equation in the flux geometry (as determined by EFIT) of the C-mod experiment. Bolometric measurements are utilized for the radiative loss term. We use the end wall probe measurements of electron temperature as a boundary condition and the fast scanning probe measurements of upstream temperature are treated as constraints to determine the cross field transport and thermal conductivity. Results are compared with 1-D onion-skin-model predictions.

  1. Microstructure in Worn Surface of Hadfield Steel Crossing

    NASA Astrophysics Data System (ADS)

    Zhang, F. C.; Lv, B.; Wang, T. S.; Zheng, C. L.; Li, M.; Zhang, M.

    In this paper a failed Hadfield (high manganese austenite) steel crossing used in railway system was studied. The microstructure in the worn surfaces of the crossing was investigated using optical microscopy, scanning electron microscopy, transmission electron microscopy and Mössbauer spectroscopy. The results indicated that a nanocrystallization layer formed on the surface of the crossing served. The formation mechanism of the nanocrystalline is the discontinuous dynamic recrystallization. The energy for the recrystallization nucleus formation originates from the interactions between the twins, the dislocations, as well as twin and dislocation. High-density vacancies promoted the recrystallization process including the dislocation climb and the atom diffusion.

  2. Layers in Oudemans

    NASA Technical Reports Server (NTRS)

    2004-01-01

    24 July 2004 The central peak of Oudemans Crater, located near 10.0oS, 92.1oW, contains light-toned, layered rock that has been uplifted and severely tilted. When seen from overhead, as in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, the dipping layered rocks form a banded pattern on the landscape. These rocks were once in the ground beneath the present floor of Oudemans Crater. The impact which produced the crater brought these rocks to the surface. They are light-toned and very similar to some of the varieties of sedimentary rock outcrops found in portions of the vast Valles Marineris trough system. Oudemans Crater sits on the edge of the Valles Marineris, near the intersection of the Labyrinthus Noctis and Ius Chasma. The image is illuminated by sunlight from the left/upper left. The 180 meter scale bar is equal to about 197 yards.

  3. Crack layer theory

    NASA Technical Reports Server (NTRS)

    Chudnovsky, A.

    1984-01-01

    A damage parameter is introduced in addition to conventional parameters of continuum mechanics and consider a crack surrounded by an array of microdefects within the continuum mechanics framework. A system consisting of the main crack and surrounding damage is called crack layer (CL). Crack layer propagation is an irreversible process. The general framework of the thermodynamics of irreversible processes are employed to identify the driving forces (causes) and to derive the constitutive equation of CL propagation, that is, the relationship between the rates of the crack growth and damage dissemination from one side and the conjugated thermodynamic forces from another. The proposed law of CL propagation is in good agreement with the experimental data on fatigue CL propagation in various materials. The theory also elaborates material toughness characterization.

  4. Layered seal for turbomachinery

    DOEpatents

    Sarawate, Neelesh Nandkumar; Morgan, Victor John; Weber, David Wayne

    2015-11-20

    The present application provides seal assemblies for reducing leakages between adjacent components of turbomachinery. The seal assemblies may include outer shims, and at least a portion of the outer shims may be substantially impervious. At least one of the outer shims may be configured for sealing engagement with seal slots of the adjacent components. The seal assemblies may also include at least one of an inner shim and a filler layer positioned between the outer shims. The at least one inner shim may be substantially solid and the at least one filler layer may be relatively porous. The seal assemblies may be sufficiently flexible to account for misalignment between the adjacent components, sufficiently stiff to meet assembly requirements, and sufficiently robust to operating meet requirements associated with turbomachinery.

  5. Layered Composite Analysis Capability

    NASA Technical Reports Server (NTRS)

    Narayanaswami, R.; Cole, J. G.

    1985-01-01

    Laminated composite material construction is gaining popularity within industry as an attractive alternative to metallic designs where high strength at reduced weights is of prime consideration. This has necessitated the development of an effective analysis capability for the static, dynamic and buckling analyses of structural components constructed of layered composites. Theoretical and user aspects of layered composite analysis and its incorporation into CSA/NASTRAN are discussed. The availability of stress and strain based failure criteria is described which aids the user in reviewing the voluminous output normally produced in such analyses. Simple strategies to obtain minimum weight designs of composite structures are discussed. Several example problems are presented to demonstrate the accuracy and user convenient features of the capability.

  6. North Polar Layers

    NASA Technical Reports Server (NTRS)

    2006-01-01

    13 January 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a slope on which layered materials are exposed by erosion in the north polar region of Mars. Wind streaks are also evident in this summertime scene. The layers that make up the material beneath the ice of the north polar residual cap are typically considered to be a mixture of some amount of dust and ice, but the proportions of these constituents are not known.

    Location near: 82.6oN, 298.1oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Summer

  7. Layered Rocks in Crater

    NASA Technical Reports Server (NTRS)

    2004-01-01

    19 June 2004 Exposures of layered, sedimentary rock are common on Mars. From the rock outcrops examined by the Mars Exploration Rover, Opportunity, in Meridiani Planum to the sequence in Gale Crater's central mound that is twice the thickness of of the sedimentary rocks exposed by Arizona's Grand Canyon, Mars presents a world of sediment to study. This unusual example, imaged by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), shows eroded layer outcrops in a crater in Terra Tyrrhena near 15.4oS, 270.5oW. Sedimentary rocks provide a record of past climates and events. Perhaps someday the story told by the rocks in this image will be known via careful field work. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the left.

  8. Sedimentary Rock Layers

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-348, 2 May 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image acquired in March 2003 shows dozens of repeated layers of sedimentary rock in a western Arabia Terra crater at 8oN, 7oW. Wind has sculpted the layered forms into hills somewhat elongated toward the lower left (southwest). The dark patches at the bottom (south) end of the image are drifts of windblown sand. These sedimentary rocks might indicate that the crater was once the site of a lake--or they may result from deposition by wind in a completely dry, desert environment. Either way, these rocks have something important to say about the geologic history of Mars. The area shown is about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left.

  9. Layered Rock Ahead

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Now that solar conjunction is over so that communication between Earth and Mars is no longer blocked by the Sun, NASA's Mars Exploration Rover Spirit is continuing its trek through the 'Columbia Hills' in Gusev Crater. Straight ahead, in the foreground of this image, is a horizontally layered rock dubbed 'Tetl,' which scientists hope to investigate. Layering can be either volcanic or sedimentary in origin; researchers aim to determine which of these processes created this rock. If for some reason this particular rock is not favorably positioned for grinding and examination by the toolbox of instruments on the rover's robotic arm, Spirit will be within short reach of another similar rock, dubbed 'Coba,' just to the right, toward the middle of this image. Spirit took this image with its navigation camera on its 263rd martian day, or sol (Sept. 28, 2004).

  10. Origins of Igneous Layering

    NASA Astrophysics Data System (ADS)

    Marsh, Bruce

    Anyone who has ever seen a photo of a layered intrusion, let alone visited one first hand, or even seen a thin section from one, cannot help but be impressed by the stunning record of crystal growth and deposition. Such bodies stand as majestic monuments of undeniable evidence that intricate magmatic processes exist, processes that couple crystallization, convection, and crystal sorting to form rocks so highly ordered and beautiful that they are a wonder to behold. These are the altars to which petrologists must carry their conceived petrologic processes for approval.Although significant in number, the best layered intrusions seem to be found almost always in remote places. Their names, Bushveld, Muskox, Kiglapait, Stillwater, Duke Island, Skaergaard, Rhum, ring through igneous petrology almost as historic military battles (Saratoga, Antietam, Bull Run, Manassas, Gettysburg) do through American history. People who have worked on such bodies are almost folk heros: Wager, Deer, Brown, Jackson, Hess, Irvine, McBirney, Morse; these names are petrologic household words. Yet with all this fanfare and reverence, layered instrusions are nearly thought of as period pieces, extreme examples of what can happen, but not generally what does. This is now all changing with the increasing realization that these bodies are perhaps highly representative of all magmatic bodies. They are simply more dynamically complete, containing more of the full range of interactions, and of course, exposing a more complete record. They are one end of a spectrum containing lava flows, lava lakes, large sills, plutons, and layered intrusions. This book uniquely covers this range with an abundance of first-hand field observations and a good dose of process conceptualization, magma physics, and crystal growth kinetics.

  11. Boundary layer simulator improvement

    NASA Technical Reports Server (NTRS)

    Praharaj, S. C.; Schmitz, C.; Frost, C.; Engel, C. D.; Fuller, C. E.; Bender, R. L.; Pond, J.

    1984-01-01

    High chamber pressure expander cycles proposed for orbit transfer vehicles depend primarily on the heat energy transmitted from the combustion products through the thrust wall chamber wall. The heat transfer to the nozzle wall is affected by such variables as wall roughness, relamarization, and the presence of particles in the flow. Motor performance loss for these nozzles with thick boundary layers is inaccurate using the existing procedure coded BLIMPJ. Modifications and innovations to the code are examined. Updated routines are listed.

  12. Tropical tropopause layer

    NASA Astrophysics Data System (ADS)

    Fueglistaler, S.; Dessler, A. E.; Dunkerton, T. J.; Folkins, I.; Fu, Q.; Mote, P. W.

    2009-03-01

    Observations of temperature, winds, and atmospheric trace gases suggest that the transition from troposphere to stratosphere occurs in a layer, rather than at a sharp "tropopause." In the tropics, this layer is often called the "tropical tropopause layer" (TTL). We present an overview of observations in the TTL and discuss the radiative, dynamical, and chemical processes that lead to its time-varying, three-dimensional structure. We present a synthesis definition with a bottom at 150 hPa, 355 K, 14 km (pressure, potential temperature, and altitude) and a top at 70 hPa, 425 K, 18.5 km. Laterally, the TTL is bounded by the position of the subtropical jets. We highlight recent progress in understanding of the TTL but emphasize that a number of processes, notably deep, possibly overshooting convection, remain not well understood. The TTL acts in many ways as a "gate" to the stratosphere, and understanding all relevant processes is of great importance for reliable predictions of future stratospheric ozone and climate.

  13. Multifunctional layered magnetic composites.

    PubMed

    Siglreitmeier, Maria; Wu, Baohu; Kollmann, Tina; Neubauer, Martin; Nagy, Gergely; Schwahn, Dietmar; Pipich, Vitaliy; Faivre, Damien; Zahn, Dirk; Fery, Andreas; Cölfen, Helmut

    2015-01-01

    A fabrication method of a multifunctional hybrid material is achieved by using the insoluble organic nacre matrix of the Haliotis laevigata shell infiltrated with gelatin as a confined reaction environment. Inside this organic scaffold magnetite nanoparticles (MNPs) are synthesized. The amount of MNPs can be controlled through the synthesis protocol therefore mineral loadings starting from 15 wt % up to 65 wt % can be realized. The demineralized organic nacre matrix is characterized by small-angle and very-small-angle neutron scattering (SANS and VSANS) showing an unchanged organic matrix structure after demineralization compared to the original mineralized nacre reference. Light microscopy and confocal laser scanning microscopy studies of stained samples show the presence of insoluble proteins at the chitin surface but not between the chitin layers. Successful and homogeneous gelatin infiltration in between the chitin layers can be shown. The hybrid material is characterized by TEM and shows a layered structure filled with MNPs with a size of around 10 nm. Magnetic analysis of the material demonstrates superparamagnetic behavior as characteristic for the particle size. Simulation studies show the potential of collagen and chitin to act as nucleators, where there is a slight preference of chitin over collagen as a nucleator for magnetite. Colloidal-probe AFM measurements demonstrate that introduction of a ferrogel into the chitin matrix leads to a certain increase in the stiffness of the composite material. PMID:25671158

  14. Multifunctional layered magnetic composites

    PubMed Central

    Siglreitmeier, Maria; Wu, Baohu; Kollmann, Tina; Neubauer, Martin; Nagy, Gergely; Schwahn, Dietmar; Pipich, Vitaliy; Faivre, Damien; Zahn, Dirk; Fery, Andreas

    2015-01-01

    Summary A fabrication method of a multifunctional hybrid material is achieved by using the insoluble organic nacre matrix of the Haliotis laevigata shell infiltrated with gelatin as a confined reaction environment. Inside this organic scaffold magnetite nanoparticles (MNPs) are synthesized. The amount of MNPs can be controlled through the synthesis protocol therefore mineral loadings starting from 15 wt % up to 65 wt % can be realized. The demineralized organic nacre matrix is characterized by small-angle and very-small-angle neutron scattering (SANS and VSANS) showing an unchanged organic matrix structure after demineralization compared to the original mineralized nacre reference. Light microscopy and confocal laser scanning microscopy studies of stained samples show the presence of insoluble proteins at the chitin surface but not between the chitin layers. Successful and homogeneous gelatin infiltration in between the chitin layers can be shown. The hybrid material is characterized by TEM and shows a layered structure filled with MNPs with a size of around 10 nm. Magnetic analysis of the material demonstrates superparamagnetic behavior as characteristic for the particle size. Simulation studies show the potential of collagen and chitin to act as nucleators, where there is a slight preference of chitin over collagen as a nucleator for magnetite. Colloidal-probe AFM measurements demonstrate that introduction of a ferrogel into the chitin matrix leads to a certain increase in the stiffness of the composite material. PMID:25671158

  15. Shallow scattering layer in the subarctic pacific ocean: detection by high-frequency echo sounder.

    PubMed

    Barraclough, W E; Lebrasseur, R J; Kennedy, O D

    1969-10-31

    Shallow scattering layers consisting mainly of Calanus cristatus were detected on a trans-Pacific crossing to depths of 60 meters with a high-frequency echo sounder. Biomass estimates of these layers indicate concentrations of zoo-plankton that are greater and more extensive than previously reported in the open ocean. PMID:17778203

  16. Analysis of regimes of magnetogasdynamic interaction between a current layer and an argon flow

    NASA Astrophysics Data System (ADS)

    Vasil'ev, E. N.; Nesterov, D. A.

    2015-03-01

    A nonstationary three-dimensional magnetogasdynamics (MGD) model is used to study the dynamics of a current layer interacting with a transverse magnetic field in a supersonic argon flow through a channel of constant cross section. The MGD interaction regimes and the features of the current layer formation for various external resistances and channel widths are analyzed as based on numerical results.

  17. Surface-imprinted nanostructured layer-by-layer film for molecular recognition of theophylline derivatives.

    PubMed

    Niu, Jia; Liu, Zhihua; Fu, Long; Shi, Feng; Ma, Hongwei; Ozaki, Yukihiro; Zhang, Xi

    2008-10-21

    In this article we report the introduction of the cooperativity of various specific interactions combined with photo-cross-linking of the interlayers to yield binding sites that can realize better selectivity and imprinting efficiency of a surface molecularly imprinted LbL film (SMILbL), thus providing a new approach toward fabrication of nanostructured molecularly imprinted thin films. It involves preassembly of poly(acrylic acid) (PAA) conjugated of the theophylline residue template via a disulfide bridge, denoted as PAAtheo 15, in solution, and layer-by-layer (LbL) assembly of PAAtheo 15 and a positively charged photoreactive diazo resin (DAR) to form multilayer thin film with designed architecture. After photo-cross-linking of the film and template removal, binding sites specific to 7-(beta-hydroxyethyl)theophylline (Theo-ol) molecules are introduced within the film. Binding assay demonstrates that the SMILbL has a high selectivity of SMILbL to Theo-ol over caffeine. A control experiment demonstrates that the selectivity of SMILbL derives from nanostructured recognition sites among the layers. The imprinting amount per unit mass of the film can be 1 order of magnitude larger than that of the conventional bulk molecular imprinting systems. As this concept of construction SMILbL can be easily extended to the other molecules by the following similar protocol: its applications in building many other different molecular recognition systems are greatly anticipated. PMID:18788771

  18. Current sheet crossings in the distant magnetotail

    NASA Technical Reports Server (NTRS)

    Heikkila, W. J.

    1988-01-01

    A computer search of crossings of the field reversal region in the middle of the distant magnetotail has been done with ISEE-3 data. It is found that the instantaneous direction of the magnetic field at the crossings Bz is northward on average at a distance of 220 earth radii, with moderate values of the plasma flow. This result suggests that the magnetic field lines are closed; since the flow is tailward, the Dungey (1961) model with a steady state reconnection line across the magnetotail earthward of the spacecraft is invalidated. The present result gives strong support to a model in which tailward boundary layer flow provides the viscous interaction proposed by Axford and Hines (1961). At higher values of the plasma velocity, negative values of Bz are found.

  19. Cross-differential amplifier

    NASA Technical Reports Server (NTRS)

    Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

    2008-01-01

    A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

  20. Cross-differential amplifier

    NASA Technical Reports Server (NTRS)

    Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

    2011-01-01

    A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

  1. Cross-differential amplifier

    NASA Technical Reports Server (NTRS)

    Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

    2010-01-01

    A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

  2. Cross-differential amplifier

    NASA Technical Reports Server (NTRS)

    Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

    2013-01-01

    A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

  3. Crossed Andreev reflection-induced magnetoresistance.

    PubMed

    Giazotto, Francesco; Taddei, Fabio; Beltram, Fabio; Fazio, Rosario

    2006-08-25

    We show that very large negative magnetoresistance can be obtained in magnetic trilayers in a current-in-plane geometry owing to the existence of crossed Andreev reflection. This spin valve consists of a thin superconducting film sandwiched between two ferromagnetic layers whose magnetization is allowed to be either parallelly or antiparallelly aligned. For a suitable choice of structure parameters and nearly fully spin-polarized ferromagnets, the magnetoresistance can exceed -80%. Our results are relevant for the design and implementation of spintronic devices exploiting ferromagnet-superconductor structures. PMID:17026324

  4. Modern Thin-Layer Chromatography.

    ERIC Educational Resources Information Center

    Poole, Colin F.; Poole, Salwa K.

    1989-01-01

    Some of the important modern developments of thin-layer chromatography are introduced. Discussed are the theory and instrumentation of thin-layer chromatography including multidimensional and multimodal techniques. Lists 53 references. (CW)

  5. Protecting the ozone layer.

    PubMed

    Munasinghe, M; King, K

    1992-06-01

    Stratospheric ozone layer depletion has been recognized as a problem by the Vienna Convention for the Protection of the Ozone Layer and the 1987 Montreal Protocol (MP). The ozone layer shields the earth from harmful ultraviolet radiation (UV-B), which is more pronounced at the poles and around the equator. Industrialized countries have contributed significantly to the problem by releasing chlorofluorocarbons (CFCs) and halons into the atmosphere. The effect of these chemicals, which were known for their inertness, nonflammability, and nontoxicity, was discovered in 1874. Action to deal with the effects of CFCs and halons was initiated in 1985 in a 49-nation UN meeting. 21 nations signed a protocol limiting ozone depleting substances (ODS): CFCs and halons. Schedules were set based on each country's use in 1986; the target phaseout was set for the year 2000. The MP restricts trade in ODSs and weights the impact of substances to reflect the extent of damage; i.e., halons are 10 times more damaging than CFCs. ODS requirements for developing countries were eased to accommodate scarce resources and the small fraction of ODS emissions. An Interim Multilateral Fund under the Montreal Protocol (IMFMP) was established to provide loans to finance the costs to developing countries in meeting global environmental requirements. The IMFMP is administered by the World Bank, the UN Environmental Program, and the UN Development Program. Financing is available to eligible countries who use .3 kg of ODS/person/year. Rapid phaseout in developed countries has occurred due to strong support from industry and a lower than expected cost. Although there are clear advantages to rapid phaseout, there were no incentives included in the MP for rapid phaseout. Some of the difficulties occur because the schedules set minimum targets at the lowest possible cost. Also, costs cannot be minimized by a country-specific and ODS-specific process. The ways to improve implementation in scheduling and

  6. The Keck keyword layer

    NASA Technical Reports Server (NTRS)

    Conrad, A. R.; Lupton, W. F.

    1992-01-01

    Each Keck instrument presents a consistent software view to the user interface programmer. The view consists of a small library of functions, which are identical for all instruments, and a large set of keywords, that vary from instrument to instrument. All knowledge of the underlying task structure is hidden from the application programmer by the keyword layer. Image capture software uses the same function library to collect data for the image header. Because the image capture software and the instrument control software are built on top of the same keyword layer, a given observation can be 'replayed' by extracting keyword-value pairs from the image header and passing them back to the control system. The keyword layer features non-blocking as well as blocking I/O. A non-blocking keyword write operation (such as setting a filter position) specifies a callback to be invoked when the operation is complete. A non-blocking keyword read operation specifies a callback to be invoked whenever the keyword changes state. The keyword-callback style meshes well with the widget-callback style commonly used in X window programs. The first keyword library was built for the two Keck optical instruments. More recently, keyword libraries have been developed for the infrared instruments and for telescope control. Although the underlying mechanisms used for inter-process communication by each of these systems vary widely (Lick MUSIC, Sun RPC, and direct socket I/O, respectively), a basic user interface has been written that can be used with any of these systems. Since the keyword libraries are bound to user interface programs dynamically at run time, only a single set of user interface executables is needed. For example, the same program, 'xshow', can be used to display continuously the telescope's position, the time left in an instrument's exposure, or both values simultaneously. Less generic tools that operate on specific keywords, for example an X display that controls optical

  7. Cooperating systems: Layered MAS

    NASA Technical Reports Server (NTRS)

    Rochowiak, Daniel

    1990-01-01

    Distributed intelligent systems can be distinguished by the models that they use. The model developed focuses on layered multiagent system conceived of as a bureaucracy in which a distributed data base serves as a central means of communication. The various generic bureaus of such a system is described and a basic vocabulary for such systems is presented. In presenting the bureaus and vocabularies, special attention is given to the sorts of reasonings that are appropriate. A bureaucratic model has a hierarchy of master system and work group that organizes E agents and B agents. The master system provides the administrative services and support facilities for the work groups.

  8. Defect Formation in GaN Epitaxial Layers due to SHI Irradiation

    SciTech Connect

    Kumar, Ashish; Kumar, V.; Singh, R.; Kanjilal, D.

    2011-07-15

    GaN epitaxial layers were irradiated with 200 MeV swift heavy Ag ions at various fluences. These samples were then characterized by XRD and TEM. Increase in peak width (FWHM) with incident ion dose showed reduction in crystallinity of epitaxial layers. Cross sectional TEM images confirmed that at highest fluence (5x10{sup 12} ions/cm{sup 2}) electronic energy loss process caused structural defect formation in GaN layer.

  9. Boundary layer ozone - An airborne survey above the Amazon Basin

    NASA Technical Reports Server (NTRS)

    Gregory, Gerald L.; Browell, Edward V.; Warren, Linda S.

    1988-01-01

    Ozone data obtained over the forest canopy of the Amazon Basin during July and August 1985 in the course of NASA's Amazon Boundary Layer Experiment 2A are discussed, and ozone profiles obtained during flights from Belem to Tabatinga, Brazil, are analyzed to determine any cross-basin effects. The analyses of ozone data indicate that the mixed layer of the Amazon Basin, for the conditions of undisturbed meteorology and in the absence of biomass burning, is a significant sink for tropospheric ozone. As the coast is approached, marine influences are noted at about 300 km inland, and a transition from a forest-controlled mixed layer to a marine-controlled mixed layer is noted.

  10. Advanced atom chips with two metal layers.

    SciTech Connect

    Stevens, James E.; Blain, Matthew Glenn; Benito, Francisco M.; Biedermann, Grant

    2010-12-01

    A design concept, device layout, and monolithic microfabrication processing sequence have been developed for a dual-metal layer atom chip for next-generation positional control of ultracold ensembles of trapped atoms. Atom chips are intriguing systems for precision metrology and quantum information that use ultracold atoms on microfabricated chips. Using magnetic fields generated by current carrying wires, atoms are confined via the Zeeman effect and controllably positioned near optical resonators. Current state-of-the-art atom chips are single-layer or hybrid-integrated multilayer devices with limited flexibility and repeatability. An attractive feature of multi-level metallization is the ability to construct more complicated conductor patterns and thereby realize the complex magnetic potentials necessary for the more precise spatial and temporal control of atoms that is required. Here, we have designed a true, monolithically integrated, planarized, multi-metal-layer atom chip for demonstrating crossed-wire conductor patterns that trap and controllably transport atoms across the chip surface to targets of interest.

  11. Cross-Cultural HRD.

    ERIC Educational Resources Information Center

    1995

    These five papers are from a symposium that was facilitated by David C. Bjorkquist on cross-cultural human resource development (HRD) at the 1995 Academy of Human Resource Development conference. "Developing Managers for Overseas Assignments in the Pacific Rim: A Study of International HRD Issues in Singapore" (A. Ahad M. Osman-Gani, Thian-Ser…

  12. Crossing the Writing Threshold.

    ERIC Educational Resources Information Center

    Clark, Carol Lea

    What pushes a writer over the edge of thought into text production--over what may be called "the writing threshold?" This is the moment when the thoughts in a writer's mind, the writing situation, and personal motivations create a momentum that results in a pattern of written words. There is evidence that not everyone crosses the writing threshold…

  13. Cross-correlation beamforming

    NASA Astrophysics Data System (ADS)

    Ruigrok, Elmer; Gibbons, Steven; Wapenaar, Kees

    2016-10-01

    An areal distribution of sensors can be used for estimating the direction of incoming waves through beamforming. Beamforming may be implemented as a phase-shifting and stacking of data recorded on the different sensors (i.e., conventional beamforming). Alternatively, beamforming can be applied to cross-correlations between the waveforms on the different sensors. We derive a kernel for beamforming cross-correlated data and call it cross-correlation beamforming (CCBF). We point out that CCBF has slightly better resolution and aliasing characteristics than conventional beamforming. When auto-correlations are added to CCBF, the array response functions are the same as for conventional beamforming. We show numerically that CCBF is more resilient to non-coherent noise. Furthermore, we illustrate that with CCBF individual receiver-pairs can be removed to improve mapping to the slowness domain. An additional flexibility of CCBF is that cross-correlations can be time-windowed prior to beamforming, e.g., to remove the directionality of a scattered wavefield. The observations on synthetic data are confirmed with field data from the SPITS array (Svalbard). Both when beamforming an earthquake arrival and when beamforming ambient noise, CCBF focuses more of the energy to a central beam. Overall, the main advantage of CCBF is noise suppression and its flexibility to remove station pairs that deteriorate the signal-related beampower.

  14. Cross-Cultural HRD.

    ERIC Educational Resources Information Center

    1996

    This document consists of three papers presented at a symposium on cross-cultural human resource development (HRD) moderated by Connie Fletcher at the 1996 conference of the Academy of Human Resource Development. "Intercultural Adjustment of U.S. Expatriates in the People's Republic of China" (Hallett G. Hullinger, Robert E. Nolan) presents…

  15. Red Cross Swimming Update.

    ERIC Educational Resources Information Center

    Vlasich, Cynthia

    1989-01-01

    Six new aquatic courses, developed by the Red Cross, are described. They are: Infant and Preschool Aquatics, Longfellow's Whale Tales (classroom water safety lessons for K-Six), Basic Water Safety, Emergency Water Safety, Lifeguard Training, and Safety Training for Swim Coaches. (IAH)

  16. Layered kagome spin ice

    NASA Astrophysics Data System (ADS)

    Hamp, James; Dutton, Sian; Mourigal, Martin; Mukherjee, Paromita; Paddison, Joseph; Ong, Harapan; Castelnovo, Claudio

    Spin ice materials provide a rare instance of emergent gauge symmetry and fractionalisation in three dimensions: the effective degrees of freedom of the system are emergent magnetic monopoles, and the extensively many `ice rule' ground states are those devoid of monopole excitations. Two-dimensional (kagome) analogues of spin ice have also been shown to display a similarly rich behaviour. In kagome ice however the ground-state `ice rule' condition implies the presence everywhere of magnetic charges. As temperature is lowered, an Ising transition occurs to a charge-ordered state, which can be mapped to a dimer covering of the dual honeycomb lattice. A second transition, of Kosterlitz-Thouless or three-state Potts type, occurs to a spin-ordered state at yet lower temperatures, due to small residual energy differences between charge-ordered states. Inspired by recent experimental capabilities in growing spin ice samples with selective (layered) substitution of non-magnetic ions, in this work we investigate the fate of the two ordering transitions when individual kagome layers are brought together to form a three-dimensional pyrochlore structure coupled by long range dipolar interactions. We also consider the response to substitutional disorder and applied magnetic fields.

  17. Turbulent boundary layer heat

    NASA Astrophysics Data System (ADS)

    Finson, M. L.; Clarke, A. S.; Wu, P. K. S.

    1981-01-01

    A Reynolds stress model for turbulent boundary layers is used to study surface roughness effects on skin friction and heat transfer. The issues of primary interest are the influence of roughness character (element shape and spacing) and the nature of roughness effects at high Mach numbers. Computations based on the model compare satisfactorily with measurements from experiments involving variations in roughness character, in low speed and modestly supersonic conditions. The more limited data base at hypersonic Mach numbers is also examined with reasonable success, although no quantitative explanation is offered for the reduction of heat transfer with increasing roughness observed by Holden at Me -9.4. The present calculations indicate that the mean velocity is approximately uniform over much of the height range below the tops of the elements, y less than or equal to k. With this constant (roughness velocity,) it is simple to estimate the form drag on the elements. This roughness velocity has been investigated by systematically exercising the present model over ranges of potential parameters. The roughness velocity is found to be primarily a function of the projected element frontal area per unit surface area, thus providing a new and simple method for predicting roughness character effects. The model further suggests that increased boundary layer temperatures should be generated by roughness at high edge Mach numbers, which would tend to reduce skin friction and heat transfer, perhaps below smooth wall levels.

  18. The Boundary Layer Radiometer

    NASA Astrophysics Data System (ADS)

    Irshad, Ranah; Bowles, N. E.; Calcutt, S. B.; Hurley, J.

    2010-10-01

    The Boundary Layer Radiometer is a small, low mass (<1kg) radiometer with only a single moving part - a scan/calibration mirror. The instrument consists of a three mirror telescope system incorporating an intermediate focus for use with miniature infrared and visible filters. It also has an integrated low power blackbody calibration target to provide long-term calibration stability The instrument may be used as an upward looking boundary layer radiometer for both the terrestrial and Martian atmospheres with appropriate filters for the mid-infrared carbon dioxide band, as well as a visible channel for the detection of aerosol components such as dust. The scan mirror may be used to step through different positions from the local horizon to the zenith, allowing the vertical temperature profile of the atmosphere to be retrieved. The radiometer uses miniature infrared filter assemblies developed for previous space-based instruments by Oxford, Cardiff and Reading Universities. The intermediate focus allows for the use of upstream blocking filters and baffles, which not only simplifies the design of the filters and focal plane assembly, but also reduces the risk of problems due to stray light. Combined with the calibration target this means it has significant advantages over previous generations of small radiometers.

  19. Buried oxide layer in silicon

    DOEpatents

    Sadana, Devendra Kumar; Holland, Orin Wayne

    2001-01-01

    A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

  20. Metal deposition using seed layers

    DOEpatents

    Feng, Hsein-Ping; Chen, Gang; Bo, Yu; Ren, Zhifeng; Chen, Shuo; Poudel, Bed

    2013-11-12

    Methods of forming a conductive metal layers on substrates are disclosed which employ a seed layer to enhance bonding, especially to smooth, low-roughness or hydrophobic substrates. In one aspect of the invention, the seed layer can be formed by applying nanoparticles onto a surface of the substrate; and the metallization is achieved by electroplating an electrically conducting metal onto the seed layer, whereby the nanoparticles serve as nucleation sites for metal deposition. In another approach, the seed layer can be formed by a self-assembling linker material, such as a sulfur-containing silane material.

  1. Minimalist design of water-soluble cross-[beta] architecture

    SciTech Connect

    Biancalana, Matthew; Makabe, Koki; Koide, Shohei

    2010-08-13

    Demonstrated successes of protein design and engineering suggest significant potential to produce diverse protein architectures and assemblies beyond those found in nature. Here, we describe a new class of synthetic protein architecture through the successful design and atomic structures of water-soluble cross-{beta} proteins. The cross-{beta} motif is formed from the lamination of successive {beta}-sheet layers, and it is abundantly observed in the core of insoluble amyloid fibrils associated with protein-misfolding diseases. Despite its prominence, cross-{beta} has been designed only in the context of insoluble aggregates of peptides or proteins. Cross-{beta}'s recalcitrance to protein engineering and conspicuous absence among the known atomic structures of natural proteins thus makes it a challenging target for design in a water-soluble form. Through comparative analysis of the cross-{beta} structures of fibril-forming peptides, we identified rows of hydrophobic residues ('ladders') running across {beta}-strands of each {beta}-sheet layer as a minimal component of the cross-{beta} motif. Grafting a single ladder of hydrophobic residues designed from the Alzheimer's amyloid-{beta} peptide onto a large {beta}-sheet protein formed a dimeric protein with a cross-{beta} architecture that remained water-soluble, as revealed by solution analysis and x-ray crystal structures. These results demonstrate that the cross-{beta} motif is a stable architecture in water-soluble polypeptides and can be readily designed. Our results provide a new route for accessing the cross-{beta} structure and expanding the scope of protein design.

  2. Synthesis and characterization of novel forward osmosis membranes based on layer-by-layer assembly.

    PubMed

    Saren, Qi; Qiu, Chang Quan; Tang, Chuyang Y

    2011-06-15

    Forward osmosis (FO) has received considerable interest for water- and energy-related applications in recent years. FO does not require an applied pressure and is believed to have a low fouling tendency. However, a major challenge in FO is the lack of high performance FO membranes. In the current work, novel nanofiltration (NF)-like FO membranes with good magnesium chloride retention were synthesized using layer-by-layer (LbL) assembly. The membrane substrate was tailored (high porosity, finger-like pores, thin cross-section, and high hydrophilicity) to achieve a small structural parameter of 0.5 mm. Increasing the number of polyelectrolyte layers improved the selectivity of the LbL membranes while reducing their water permeability. The more selective membrane 6#LbL (with 6 polyelectrolyte layers) had much lower reverse solute transport compared to 3#LbL and 1#LbL. Meanwhile, the FO water flux was found to be strongly affected by both membrane water permeability and solute reverse transport. Severe solute reverse transport was observed for the active-layer-facing-draw-solution membrane orientation, likely due to the suppression of Donnan exclusion as a result of the high ionic strength of the draw solution. In contrast, the active-layer-facing-feed-solution orientation showed remarkable FO performance (15, 20, and 28 L/m².h at 0.1, 0.5, and 1.0 M MgCl₂, respectively, for membrane 3#LbL using distilled water as feed solution), superior to other NF-like FO membranes reported in the literature. To the best of the knowledge of the authors, this is the first work on the synthesis and characterization of LbL based FO membranes.

  3. Land and atmospheric controls on initiation and intensity of moist convection: CAPE dynamics and LCL crossings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The local role that land-atmosphere interactions play in the rainfall process has been explored by investigating the initiation of moist convection as the top of the atmospheric boundary layer (ABL) crosses the lifting condensation level (LCL). However, this LCL crossing alone is not a sufficient in...

  4. Liquefaction mechanism for layered soils

    SciTech Connect

    Fiegel, G.L.; Kutter, B.L. . Dept. of Civil and Environmental Engineering)

    1994-04-01

    Results from four centrifuge model tests are presented. Three of the model tests involve layered soil deposits subject to base shaking; one model test involves a uniform soil deposit of sand subject to base shaking. The layered soil models consisted of fine sand overlain by a layer of relatively impermeable silica flour (silt). Pore-water pressures, accelerations, and settlements were measured during all four tests. Results from the model tests involving layered soils suggest that during liquefaction a water interlayer or very loose zone of soil may develop at the sand-silt interface due to the difference in permeabilities. In each layered model test, boils were observed on the surface of the silt layer. These boils were concentrated in the thinnest zones of the overlying silt layer and provided a vent for the excess pore-water pressure generated in the fine sand.

  5. Feasibility study of a layer-oriented wavefront sensor for solar telescopes.

    PubMed

    Marino, Jose; Wöger, Friedrich

    2014-02-01

    Solar multiconjugate adaptive optics systems rely on several wavefront sensors, which measure the incoming turbulent phase along several field directions to produce a tomographic reconstruction of the turbulent phase. In this paper, we explore an alternative wavefront sensing approach that attempts to directly measure the turbulent phase present at a particular height in the atmosphere: a layer-oriented cross-correlating Shack-Hartmann wavefront sensor (SHWFS). In an experiment at the Dunn Solar Telescope, we built a prototype layer-oriented cross-correlating SHWFS system conjugated to two separate atmospheric heights. We present the data obtained in the observations and complement these with ray-tracing computations to achieve a better understanding of the instrument's performance and limitations. The results obtained in this study strongly indicate that a layer-oriented cross-correlating SHWFS is not a practical design to measure the wavefront at a high layer in the atmosphere.

  6. Double layer secure sketch

    NASA Astrophysics Data System (ADS)

    Li, Cai

    2012-09-01

    Secure sketch has been applied successfully in a wide variety of applications like cryptography, biometric authentication systems and so on. All of these secure sketches have properties in common namely error-tolerance and small entropy loss. The former ensures an input set w' can unlock the system if w' is substantially overlapped with a template set w while the latter means it is hard for an adversary to get the information of w even with the knowledge of s, which is produced by w and stored in the system publicly. In their constructions, they all consider w as a set of atomic elements. However, in the real word, it is very likely the elements in the template set are sets as well. In this paper, we propose a double layer secure sketch to address this issue.

  7. Layer Outcrops and Dunes

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-561, 1 December 2003

    This October 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows dark, windblown sand dunes amid outcrops of light-toned, sedimentary rock in a crater in western Arabia Terra. The darkest material in the scene is windblown sand; the steep slopes--the slip faces--of the dunes face toward the southwest (lower left), indicating that wind transport of sand has been from the northeast (upper right). The layered mounds are the remains of sedimentary rock that were once more extensive across this crater floor. The image is located near 8.9oN, 1.2oW, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  8. Templated, layered manganese phosphate

    DOEpatents

    Thoma, Steven G.; Bonhomme, Francois R.

    2004-08-17

    A new crystalline maganese phosphate composition having an empirical formula: O). The compound was determined to crystallize in the trigonal space group P-3c1 with a=8.8706(4) .ANG., c=26.1580(2) .ANG., and V (volume)=1783 .ANG..sup.3. The structure consists of sheets of corner sharing Mn(II)O.sub.4 and PO.sub.4 tetrahedra with layers of (H.sub.3 NCH.sub.2 CH.sub.2).sub.3 N and water molecules in-between. The pronated (H.sub.3 NCH.sub.2 CH.sub.2).sub.3 N molecules provide charge balancing for the inorganic sheets. A network of hydrogen bonds between water molecules and the inorganic sheets holds the structure together.

  9. Layers in Tithonium

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-570, 10 December 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows eroded layered bedrock outcrops in the upper walls of one of the depressions in the Tithonium Chasma trough system. Tithonium Chasma is one of the canyons of the Valles Marineris, a vast gouge that--if it occurred on Earth-would span the distance from Los Angeles, California, to New York City. The Valles Marineris canyons were not carved by running water, instead they formed mostly by the combined forces of faulting and mass movement (landslides) as gravity eroded materials from the walls. This image is located near 4.2oS, 85.1oW. The image covers an area approximately 3 km (1.9 mi) wide and is illuminated from the lower left.

  10. Ozone Layer Observations

    NASA Technical Reports Server (NTRS)

    McPeters, Richard; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    The US National Aeronautics and Space Administration (NASA) has been monitoring the ozone layer from space using optical remote sensing techniques since 1970. With concern over catalytic destruction of ozone (mid-1970s) and the development of the Antarctic ozone hole (mid-1980s), long term ozone monitoring has become the primary focus of NASA's series of ozone measuring instruments. A series of TOMS (Total Ozone Mapping Spectrometer) and SBUV (Solar Backscatter Ultraviolet) instruments has produced a nearly continuous record of global ozone from 1979 to the present. These instruments infer ozone by measuring sunlight backscattered from the atmosphere in the ultraviolet through differential absorption. These measurements have documented a 15 Dobson Unit drop in global average ozone since 1980, and the declines in ozone in the antarctic each October have been far more dramatic. Instruments that measure the ozone vertical distribution, the SBUV and SAGE (Stratospheric Aerosol and Gas Experiment) instruments for example, show that the largest changes are occurring in the lower stratosphere and upper troposphere. The goal of ozone measurement in the next decades will be to document the predicted recovery of the ozone layer as CFC (chlorofluorocarbon) levels decline. This will require a continuation of global measurements of total column ozone on a global basis, but using data from successor instruments to TOMS. Hyperspectral instruments capable of measuring in the UV will be needed for this purpose. Establishing the relative roles of chemistry and dynamics will require instruments to measure ozone in the troposphere and in the stratosphere with good vertical resolution. Instruments that can measure other chemicals important to ozone formation and destruction will also be needed.

  11. Multichannel MAC Layer In Mobile Ad—Hoc Network

    NASA Astrophysics Data System (ADS)

    Logesh, K.; Rao, Samba Siva

    2010-11-01

    This paper we presented the design objectives and technical challenges in Multichannel MAC protocols in Mobile Ad-hoc Network. In IEEE 802.11 a/b/g standards allow use of multiple channels, only a single channel is popularly used, due to the lack of efficient protocols that enable use of Multiple Channels. Even though complex environments in ad hoc networks require a combined control of physical (PHY) and medium access control (MAC) layers resources in order to optimize performance. And also we discuss the characteristics of cross-layer frame and give a multichannel MAC approach.

  12. Active microwave remote sensing of an anisotropic random medium layer

    NASA Technical Reports Server (NTRS)

    Lee, J. K.; Kong, J. A.

    1985-01-01

    A two-layer anisotropic random medium model has been developed to study the active remote sensing of the earth. The dyadic Green's function for a two-layer anisotropic medium is developed and used in conjunction with the first-order Born approximation to calculate the backscattering coefficients. It is shown that strong cross-polarization occurs in the single scattering process and is indispensable in the interpretation of radar measurements of sea ice at different frequencies, polarizations, and viewing angles. The effects of anisotropy on the angular responses of backscattering coefficients are also illustrated.

  13. ZnO layers deposited by Atomic Layer Deposition

    NASA Astrophysics Data System (ADS)

    Pécz, B.; Baji, Zs; Lábadi, Z.; Kovács, A.

    2013-11-01

    The structure of 40 nm thick epitaxial ZnO layers grown on single crystalline sapphire and GaN substrates by atomic layer deposition has been studied using transmission electron microscopy. The growth is carried out between 150°C and 300°C without any buffer layer using di-ethyl zinc and water precursors. The ZnO layer on sapphire is found to be polycrystalline, which is probably due to the large misfit (~15 %) and the relatively low deposition temperature. However, the small misfit (~1.8 %) between the ZnO layer that is deposited on GaN at 300°C resulted in a high quality single crystalline layer.

  14. Processes for multi-layer devices utilizing layer transfer

    DOEpatents

    Nielson, Gregory N; Sanchez, Carlos Anthony; Tauke-Pedretti, Anna; Kim, Bongsang; Cederberg, Jeffrey; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J

    2015-02-03

    A method includes forming a release layer over a donor substrate. A plurality of devices made of a first semiconductor material are formed over the release layer. A first dielectric layer is formed over the plurality of devices such that all exposed surfaces of the plurality of devices are covered by the first dielectric layer. The plurality of devices are chemically attached to a receiving device made of a second semiconductor material different than the first semiconductor material, the receiving device having a receiving substrate attached to a surface of the receiving device opposite the plurality of devices. The release layer is etched to release the donor substrate from the plurality of devices. A second dielectric layer is applied over the plurality of devices and the receiving device to mechanically attach the plurality of devices to the receiving device.

  15. 13. WAIKOLU STREAM CROSSING NO. 1, FIRST CROSSING OF WAIKOLU ...

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

    13. WAIKOLU STREAM CROSSING NO. 1, FIRST CROSSING OF WAIKOLU STREAM, VIEW UPSTREAM. CONSTRUCTED OF CONCRETE AND RUBBLE MASONRY, PIPELINE IS ENCASED WITHIN. - Kalaupapa Water Supply System, Waikolu Valley to Kalaupapa Settlement, Island of Molokai, Kalaupapa, Kalawao County, HI

  16. Inter-layer synchronization in multiplex networks of identical layers.

    PubMed

    Sevilla-Escoboza, R; Sendiña-Nadal, I; Leyva, I; Gutiérrez, R; Buldú, J M; Boccaletti, S

    2016-06-01

    Inter-layer synchronization is a distinctive process of multiplex networks whereby each node in a given layer evolves synchronously with all its replicas in other layers, irrespective of whether or not it is synchronized with the other units of the same layer. We analytically derive the necessary conditions for the existence and stability of such a state, and verify numerically the analytical predictions in several cases where such a state emerges. We further inspect its robustness against a progressive de-multiplexing of the network, and provide experimental evidence by means of multiplexes of nonlinear electronic circuits affected by intrinsic noise and parameter mismatch. PMID:27368794

  17. Universal enveloping crossed module of Leibniz crossed modules and representations

    NASA Astrophysics Data System (ADS)

    Casado, Rafael F.; García-Martínez, Xabier; Ladra, Manuel

    2016-03-01

    The universal enveloping algebra functor UL: Lb → Alg, defined by Loday and Pirashvili [1], is extended to crossed modules. Then we construct an isomorphism between the category of representations of a Leibniz crossed module and the category of left modules over its universal enveloping crossed module of algebras. Note that the procedure followed in the proof for the Lie case cannot be adapted, since the actor in the category of Leibniz crossed modules does not always exist.

  18. Neutral sheet crossings by ISEE-3 in the distant magnetotail

    NASA Technical Reports Server (NTRS)

    Heikkila, W. J.; Slavin, J. A.; Smith, E. J.; Baker, D. N.; Zwickl, R. D.

    1986-01-01

    Magnetic field data from ISEE-3 in the distant magnetotail at crossings of the field reversal (or neutral sheet) region were analyzed to determine the instantaneous direction of the normal component Bz at the crossing. A crossing identified as being almost always tailward of the steady-state X-line was selected. Data for 1 hr are discussed to illustrate difficulties. One particular smooth crossing shows that complicated microstructure can occur in times less than 1 min. Averaging over long times may eliminate essential information. Inspection of the magnetic field data at the highest resolution, however, shows that the direction of the plasma sheet flows and the sense of Bz across the neutral sheet do not always agree with the reconnection models. Rather, they indicate that the low latitude boundary layer may play a significant role in the dynamics of the magnetotail.

  19. Microanalysis of deposited layers in the divertor of JET following operations with carbon wall

    NASA Astrophysics Data System (ADS)

    Bergsåker, H.; Petersson, P.; Bykov, I.; Possnert, G.; Likonen, J.; Koivuranta, S.; Coad, J. P.; Widdowson, A. M.; JET EFDA contributors

    2013-07-01

    Elemental mapping of cross sections of deposited layers on inboard tiles in the JET divertor after exposure to plasma operations with carbon wall are presented. The study was made using microbeam ion beam analysis methods in combination with optical microscopy and SEM. The surfaces had been exposed to plasma through different periods of operation (1998-2007, 2007-2009 and 1998-2009). The texture and composition of the layers are non-uniform. The physical structures include columnar, lamellar and disordered globular appearances. The distribution of trapped deuterium was frequently found to be lamellar, with well-defined sub layers with higher deuterium concentration. However, 3D regions with dimensions of about 100 μm with enhanced deuterium content were also found, both at the layer surfaces and in the layer cross sections. The distributions of beryllium and Inconel components were lamellar but did not otherwise show large non-uniformity on the same scale length as the deuterium.

  20. Boundary-Layer & health

    NASA Astrophysics Data System (ADS)

    Costigliola, V.

    2010-09-01

    It has long been known that specific atmospheric processes, such as weather and longer-term climatic fluctuations, affect human health. The biometeorological literature refers to this relationship as meteorotropism, defined as a change in an organism that is correlated with a change in atmospheric conditions. Plenty of (patho)physiological functions are affected by those conditions - like the respiratory diseases - and currently it is difficult to put any limits for pathologies developed in reply. Nowadays the importance of atmospheric boundary layer and health is increasingly recognised. A number of epidemiologic studies have reported associations between ambient concentrations of air pollution, specifically particulate pollution, and adverse health effects, even at the relatively low concentrations of pollution found. Since 1995 there have been over twenty-one studies from four continents that have explicitly examined the association between ambient air pollutant mixes and daily mortality. Statistically significant and positive associations have been reported in data from various locations around the world, all with varying air pollutant concentrations, weather conditions, population characteristics and public health policies. Particular role has been given to atmospheric boundary layer processes, the impact of which for specific patient-cohort is, however, not well understood till now. Assessing and monitoring air quality are thus fundamental to improve Europe's welfare. One of current projects run by the "European Medical Association" - PASODOBLE will develop and demonstrate user-driven downstream information services for the regional and local air quality sectors by combining space-based and in-situ data with models in 4 thematic service lines: - Health community support for hospitals, pharmacies, doctors and people at risk - Public information for regions, cities, tourist industry and sporting event organizers - Compliance monitoring support on particulate

  1. Development of 40 GB dual-layer rewritable HD DVD media

    NASA Astrophysics Data System (ADS)

    Satoh, Yasuhiro; Nakai, Tsukasa; Ashida, Sumio

    2007-06-01

    We have developed a single-side dual-layer rewritable HD DVD media having a larger capacity of 40 GB (20 GB per layer) for the optical system with the NA of 0.65 and the wavelength of 405 nm, and achieved the good recording characteristics. For both layers, the same track pitch of 0.34 μm as HD DVD-RAM was used. We applied more accurate thermal analysis to the dual-layer rewritable media. It was expected that the effect of the cross-erase was very small. By optimizing thermal balance of dual-layer media, the good recording characteristics were obtained for both layers with enough tilt margins. The feasibility of the dual-layer rewritable media of 40 GB user data capacity was shown for HD DVD system.

  2. Excited waves in shear layers

    NASA Technical Reports Server (NTRS)

    Bechert, D. W.

    1982-01-01

    The generation of instability waves in free shear layers is investigated. The model assumes an infinitesimally thin shear layer shed from a semi-infinite plate which is exposed to sound excitation. The acoustical shear layer excitation by a source further away from the plate edge in the downstream direction is very weak while upstream from the plate edge the excitation is relatively efficient. A special solution is given for the source at the plate edge. The theory is then extended to two streams on both sides of the shear layer having different velocities and densities. Furthermore, the excitation of a shear layer in a channel is calculated. A reference quantity is found for the magnitude of the excited instability waves. For a comparison with measurements, numerical computations of the velocity field outside the shear layer were carried out.

  3. Streamwise vortex meander in a plane mixing layer

    NASA Technical Reports Server (NTRS)

    Leboeuf, Richard L.; Mehta, Rabindra D.

    1993-01-01

    The present experimental study was conducted in order to determine the existence of streamwise vortex meander in a mixing layer, and if present, its significance on the measured properties. The dependence of the velocity cross-correlation on the fixed probe location was shown to be a good indicator of the stationarity of the streamwise vortex location. The cross-correlation measurements obtained here indicate that spanwise meander is negligible, although transverse apparent meander (normal to the plane of the mixing layer) was indicated. The transverse meander, exemplified by the elliptical shape of the mean streamwise vorticity contours, was expected, since the streamwise vorticity in the braid region is essentially inclined, with respect to the streamwise direction. These conclusions were supported by results of estimated spanwise profiles of the transverse velocity component. The balance of evidence suggests that the measured mean streamwise vorticity decay is representative of the decay of the vorticity rather than an artifact of meander.

  4. Oxygen-reducing catalyst layer

    DOEpatents

    O'Brien, Dennis P.; Schmoeckel, Alison K.; Vernstrom, George D.; Atanasoski, Radoslav; Wood, Thomas E.; Yang, Ruizhi; Easton, E. Bradley; Dahn, Jeffrey R.; O'Neill, David G.

    2011-03-22

    An oxygen-reducing catalyst layer, and a method of making the oxygen-reducing catalyst layer, where the oxygen-reducing catalyst layer includes a catalytic material film disposed on a substrate with the use of physical vapor deposition and thermal treatment. The catalytic material film includes a transition metal that is substantially free of platinum. At least one of the physical vapor deposition and the thermal treatment is performed in a processing environment comprising a nitrogen-containing gas.

  5. Layers of looking

    PubMed Central

    Morris, Wendy

    2011-01-01

    The films that I make are part documentary, part film essay, part visual poem. They are created out of a series of up to 30 drawings that are animated. The process from research to completion takes about 2 years, and at the end of it there is a film and a number of drawings that can be exhibited. This paper emerges out of the realisation that in the different stages of making a drawing and a film—from planning a drawing and seeking an image as a starting point through to the finished film being projected onto a screen in a gallery—I am looking at the image in different ways. There is a close-up kind of looking when I am drawing and a reflective kind of looking when I step back to take stock. There is a way of looking at darks and lights as they are built up that is different from the way of looking at the lines crossing the edges of the grid being used to transfer an image to the drawing paper. Seeing the drawings on the wall of my studio is different from seeing the same drawings in a museum setting. PMID:23145247

  6. The Martian surface layer

    NASA Technical Reports Server (NTRS)

    Christensen, Philip R.; Moore, Henry J.

    1992-01-01

    The global characteristics of the Martian surface layer are discussed on the basis of thermal, albedo, color, and radar data for the region between approximately 60 deg S and 60 deg N. Thermal data reveal the presence of large low- and high-inertia regions of the northern hemisphere, with much of the south covered by material of moderate inertia. There is a strong anticorrelation between inertia and albedo, a correlation between inertia and rock abundance, and, over much of the planet, a correlation of radar-derived density with inertia. Viking Orbiter color data indicate the presence of three major surface materials: low-inertia, bright-red material that is presumably dust; high-inertia, dark-grey material interpreted to be lithic material mixed with palagonitelike dust; and moderate-inertia, dark-red material that is rough at subpixel scales and interpreted to be indurated. Observations from the Viking landing sites show rocks, fines of varying cohesion and crusts. These sites have indications of aeolian erosion and deposition in the recent past.

  7. Outer layer effects in wind-farm boundary layers: Coriolis forces and boundary layer height

    NASA Astrophysics Data System (ADS)

    Allaerts, Dries; Meyers, Johan

    2015-11-01

    In LES studies of wind-farm boundary layers, scale separation between the inner and outer region of the atmospheric boundary layer (ABL) is frequently assumed, i.e., wind turbines are presumed to fall within the inner layer and are not affected by outer layer effects. However, modern wind turbine and wind farm design tends towards larger rotor diameters and farm sizes, which means that outer layer effects will become more important. In a prior study, it was already shown for fully-developed wind farms that the ABL height influences the power performance. In this study, we use the in-house LES code SP-Wind to investigate the importance of outer layer effects on wind-farm boundary layers. In a suite of LES cases, the ABL height is varied by imposing a capping inversion with varying inversion strengths. Results indicate the growth of an internal boundary layer (IBL), which is limited in cases with low inversion layers. We further find that flow deceleration combined with Coriolis effects causes a change in wind direction throughout the farm. This effect increases with decreasing boundary layer height, and can result in considerable turbine wake deflection near the end of the farm. The authors are supported by the ERC (ActiveWindFarms, grant no: 306471). Computations were performed on VSC infrastructiure (Flemish Supercomputer Center), funded by the Hercules Foundation and the Flemish Government-department EWI.

  8. Midlatitude sporadic-E layers

    NASA Technical Reports Server (NTRS)

    Smith, L. G.; Miller, K. L.

    1981-01-01

    Rocket borne probes and incoherent scatter radar were demonstrated to be effective methods of studying the structure of midlatitude sporadic E layers. Layers are formed when metal ions are converged vertically in a wind shear to produce a local enhancement of electron density. Rocket and radar observations show that the layers may occassionally have complex structure produced by an unstable wind shear. The partial transparency to radio waves of sporadic E layers is shown to be due to localized regions of high electron density.

  9. Secondary polymer layered impregnated tile

    NASA Technical Reports Server (NTRS)

    Tran, Huy K. (Inventor); Rasky, Daniel J. (Inventor); Szalai, Christine E. (Inventor); Carroll, Joseph A. (Inventor); Hsu, Ming-ta S. (Inventor)

    2005-01-01

    A low density organic polymer impregnated preformed fibrous ceramic article includes a plurality of layers. A front layer includes ceramic fibers or carbon fibers or combinations of ceramic fibers and carbon fibers, and is impregnated with an effective amount of at least one organic polymer. A middle layer includes polymer impregnated ceramic fibers. A back layer includes ceramic fibers or carbon fibers or combinations of ceramic fibers and carbon fibers, and is impregnated with an effective amount of at least one low temperature pyrolyzing organic polymer capable of decomposing without depositing residues.

  10. Layer Control of WSe2 via Selective Surface Layer Oxidation.

    PubMed

    Li, Zhen; Yang, Sisi; Dhall, Rohan; Kosmowska, Ewa; Shi, Haotian; Chatzakis, Ioannis; Cronin, Stephen B

    2016-07-26

    We report Raman and photoluminescence spectra of mono- and few-layer WSe2 and MoSe2 taken before and after exposure to a remote oxygen plasma. For bilayer and trilayer WSe2, we observe an increase in the photoluminescence intensity and a blue shift of the photoluminescence peak positions after oxygen plasma treatment. The photoluminescence spectra of trilayer WSe2 exhibit features of a bilayer after oxygen plasma treatment. Bilayer WSe2 exhibits features of a monolayer, and the photoluminescence of monolayer WSe2 is completely absent after the oxygen plasma treatment. These changes are observed consistently in more than 20 flakes. The mechanism of the changes observed in the photoluminescence spectra of WSe2 is due to the selective oxidation of the topmost layer. As a result, N-layer WSe2 is reduced to N-1 layers. Raman spectra and AFM images taken from the WSe2 flakes before and after the oxygen treatment corroborate these findings. Because of the low kinetic energy of the oxygen radicals in the remote oxygen plasma, the oxidation is self-limiting. By varying the process duration from 1 to 10 min, we confirmed that the oxidation will only affect the topmost layer of the WSe2 flakes. X-ray photoelectron spectroscopy shows that the surface layer WOx of the sample can be removed by a quick dip in KOH solution. Therefore, this technique provides a promising way of controlling the thickness of WSe2 layer by layer. PMID:27391161

  11. Layer-layer competition in multiplex complex networks.

    PubMed

    Gómez-Gardeñes, J; de Domenico, M; Gutiérrez, G; Arenas, A; Gómez, S

    2015-12-13

    The coexistence of multiple types of interactions within social, technological and biological networks has moved the focus of the physics of complex systems towards a multiplex description of the interactions between their constituents. This novel approach has unveiled that the multiplex nature of complex systems has strong influence in the emergence of collective states and their critical properties. Here we address an important issue that is intrinsic to the coexistence of multiple means of interactions within a network: their competition. To this aim, we study a two-layer multiplex in which the activity of users can be localized in each of the layers or shared between them, favouring that neighbouring nodes within a layer focus their activity on the same layer. This framework mimics the coexistence and competition of multiple communication channels, in a way that the prevalence of a particular communication platform emerges as a result of the localization of user activity in one single interaction layer. Our results indicate that there is a transition from localization (use of a preferred layer) to delocalization (combined usage of both layers) and that the prevalence of a particular layer (in the localized state) depends on the structural properties.

  12. Layer-layer competition in multiplex complex networks.

    PubMed

    Gómez-Gardeñes, J; de Domenico, M; Gutiérrez, G; Arenas, A; Gómez, S

    2015-12-13

    The coexistence of multiple types of interactions within social, technological and biological networks has moved the focus of the physics of complex systems towards a multiplex description of the interactions between their constituents. This novel approach has unveiled that the multiplex nature of complex systems has strong influence in the emergence of collective states and their critical properties. Here we address an important issue that is intrinsic to the coexistence of multiple means of interactions within a network: their competition. To this aim, we study a two-layer multiplex in which the activity of users can be localized in each of the layers or shared between them, favouring that neighbouring nodes within a layer focus their activity on the same layer. This framework mimics the coexistence and competition of multiple communication channels, in a way that the prevalence of a particular communication platform emerges as a result of the localization of user activity in one single interaction layer. Our results indicate that there is a transition from localization (use of a preferred layer) to delocalization (combined usage of both layers) and that the prevalence of a particular layer (in the localized state) depends on the structural properties. PMID:26527811

  13. Layer-by-Layer Proteomic Analysis of Mytilus galloprovincialis Shell

    PubMed Central

    Wang, Xin-xing; Bao, Lin-fei; Fan, Mei-hua; Li, Xiao-min; Wu, Chang-wen; Xia, Shu-wei

    2015-01-01

    Bivalve shell is a biomineralized tissue with various layers/microstructures and excellent mechanical properties. Shell matrix proteins (SMPs) pervade and envelop the mineral crystals and play essential roles in biomineralization. Despite that Mytilus is an economically important bivalve, only few proteomic studies have been performed for the shell, and current knowledge of the SMP set responsible for different shell layers of Mytilus remains largely patchy. In this study, we observed that Mytilus galloprovincialis shell contained three layers, including nacre, fibrous prism, and myostracum that is involved in shell-muscle attachment. A parallel proteomic analysis was performed for these three layers. By combining LC-MS/MS analysis with Mytilus EST database interrogations, a whole set of 113 proteins was identified, and the distribution of these proteins in different shell layers followed a mosaic pattern. For each layer, about a half of identified proteins are unique and the others are shared by two or all of three layers. This is the first description of the protein set exclusive to nacre, myostracum, and fibrous prism in Mytilus shell. Moreover, most of identified proteins in the present study are novel SMPs, which greatly extended biomineralization-related protein data of Mytilus. These results are useful, on one hand, for understanding the roles of SMPs in the deposition of different shell layers. On the other hand, the identified protein set of myostracum provides candidates for further exploring the mechanism of adductor muscle-shell attachment. PMID:26218932

  14. Layer-by-Layer Proteomic Analysis of Mytilus galloprovincialis Shell.

    PubMed

    Gao, Peng; Liao, Zhi; Wang, Xin-Xing; Bao, Lin-Fei; Fan, Mei-Hua; Li, Xiao-Min; Wu, Chang-Wen; Xia, Shu-Wei

    2015-01-01

    Bivalve shell is a biomineralized tissue with various layers/microstructures and excellent mechanical properties. Shell matrix proteins (SMPs) pervade and envelop the mineral crystals and play essential roles in biomineralization. Despite that Mytilus is an economically important bivalve, only few proteomic studies have been performed for the shell, and current knowledge of the SMP set responsible for different shell layers of Mytilus remains largely patchy. In this study, we observed that Mytilus galloprovincialis shell contained three layers, including nacre, fibrous prism, and myostracum that is involved in shell-muscle attachment. A parallel proteomic analysis was performed for these three layers. By combining LC-MS/MS analysis with Mytilus EST database interrogations, a whole set of 113 proteins was identified, and the distribution of these proteins in different shell layers followed a mosaic pattern. For each layer, about a half of identified proteins are unique and the others are shared by two or all of three layers. This is the first description of the protein set exclusive to nacre, myostracum, and fibrous prism in Mytilus shell. Moreover, most of identified proteins in the present study are novel SMPs, which greatly extended biomineralization-related protein data of Mytilus. These results are useful, on one hand, for understanding the roles of SMPs in the deposition of different shell layers. On the other hand, the identified protein set of myostracum provides candidates for further exploring the mechanism of adductor muscle-shell attachment.

  15. Cross Training and Customer Service.

    ERIC Educational Resources Information Center

    Traaen, Teri J.

    1998-01-01

    Cross training is successful when based upon personnel documentation and when providing staff development opportunities. Weekly cross-training sessions should not interfere with delivery of public services. This article suggests how job descriptions can be developed to extend cross training into everyone's daily routine and presents an action plan…

  16. Obtaining Thickness Maps of Corneal Layers Using the Optimal Algorithm for Intracorneal Layer Segmentation

    PubMed Central

    Rabbani, Hossein; Kazemian Jahromi, Mahdi; Jorjandi, Sahar; Mehri Dehnavi, Alireza; Hajizadeh, Fedra; Peyman, Alireza

    2016-01-01

    Optical Coherence Tomography (OCT) is one of the most informative methodologies in ophthalmology and provides cross sectional images from anterior and posterior segments of the eye. Corneal diseases can be diagnosed by these images and corneal thickness maps can also assist in the treatment and diagnosis. The need for automatic segmentation of cross sectional images is inevitable since manual segmentation is time consuming and imprecise. In this paper, segmentation methods such as Gaussian Mixture Model (GMM), Graph Cut, and Level Set are used for automatic segmentation of three clinically important corneal layer boundaries on OCT images. Using the segmentation of the boundaries in three-dimensional corneal data, we obtained thickness maps of the layers which are created by these borders. Mean and standard deviation of the thickness values for normal subjects in epithelial, stromal, and whole cornea are calculated in central, superior, inferior, nasal, and temporal zones (centered on the center of pupil). To evaluate our approach, the automatic boundary results are compared with the boundaries segmented manually by two corneal specialists. The quantitative results show that GMM method segments the desired boundaries with the best accuracy. PMID:27247559

  17. A general approach for the prediction of localized instability generation in boundary layer flows

    NASA Technical Reports Server (NTRS)

    Choudhari, Meelan; Ng, Lian; Streett, Craig L.

    1991-01-01

    The present approach to the prediction of instability generation that is due to the interaction of freestream disturbances with regions of subscale variations in surface boundary conditions can account for the finite Reynolds number effects, while furnishing a framework for the study of receptivity in compressible flow and in 3D boundary layers. The approach is illustrated for the case of Tollmien-Schlichting wave generation in a Blasius boundary layer, due to the interaction of a freestream acoustic wave with a localized wall inhomogeneity. Results are presented for the generation of viscous and inviscid instabilities in adverse pressure-gradient boundary layers, supersonic boundary layer instabilities, and cross-flow vortex instabilities.

  18. Design of the Coordinate Transformation Function for Cylindrical Acoustic Cloaks with a Quantity of Discrete Layers

    NASA Astrophysics Data System (ADS)

    Cai, Li; Wen, Ji-Hong; Yu, Dian-Long; Lu, Zhi-Miao; Wen, Xi-Sen

    2014-09-01

    Acoustic cloak based on coordinate transformation is of great topical interest and has promise in potential applications such as sound transparency and insulation. The frequency response of acoustic cloaks with a quantity of discrete homogeneous layers is analyzed by the acoustic scattering theory. The effect of coordinate transformation function on the acoustic total scattering cross section is discussed to achieve low scattering with only a few layers of anisotropic metamaterials. Also, the physics of acoustic wave interaction with the interfaces between the discrete layers inside the cloak shell is discussed. These results provide a better way of designing a multilayered acoustic cloak with fewer layers.

  19. Natural melanin composites by layer-by-layer assembly

    NASA Astrophysics Data System (ADS)

    Eom, Taesik; Shim, Bong Sub

    2015-04-01

    Melanin is an electrically conductive and biocompatible material, because their conjugated backbone structures provide conducting pathways from human skin, eyes, brain, and beyond. So there is a potential of using as materials for the neural interfaces and the implantable devices. Extracted from Sepia officinalis ink, our natural melanin was uniformly dispersed in mostly polar solvents such as water and alcohols. Then, the dispersed melanin was further fabricated to nano-thin layered composites by the layer-by-layer (LBL) assembly technique. Combined with polyvinyl alcohol (PVA), the melanin nanoparticles behave as an LBL counterpart to from finely tuned nanostructured films. The LBL process can adjust the smart performances of the composites by varying the layering conditions and sandwich thickness. We further demonstrated the melanin loading degree of stacked layers, combination nanostructures, electrical properties, and biocompatibility of the resulting composites by UV-vis spectrophotometer, scanning electron microscope (SEM), multimeter, and in-vitro cell test of PC12, respectively.

  20. Layer-by-Layer Assembly of Enzymes on Carbon Nanotubes

    SciTech Connect

    Wang, Jun; Liu, Guodong; Lin, Yuehe

    2008-06-01

    The use of Layer-by-layer techniques for immobilizing several types of enzymes, e.g. glucose oxidase (GOx), horse radish oxidases(HRP), and choline oxidase(CHO) on carbon nanotubes and their applications for biosenseing are presented. The enzyme is immobilized on the negatively charged CNT surface by alternatively assembling a cationic polydiallyldimethyl-ammonium chloride (PDDA) layer and a enzyme layer. The sandwich-like layer structure (PDDA/enzyme/PDDA/CNT) formed by electrostatic assembling provides a favorable microenvironment to keep the bioactivity of enzyme and to prevent enzyme molecule leakage. The morphologies and electrocatalytic acitivity of the resulted enzyme film were characterized using TEM and electrochemical techniques, respectively. It was found that these enzyme-based biosensors are very sensitive, selective for detection of biomolecules, e.g. glucose, choline.

  1. Cross-Cutting Faults

    NASA Technical Reports Server (NTRS)

    2005-01-01

    16 May 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows cross-cutting fault scarps among graben features in northern Tempe Terra. Graben form in regions where the crust of the planet has been extended; such features are common in the regions surrounding the vast 'Tharsis Bulge' on Mars.

    Location near: 43.7oN, 90.2oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Summer

  2. On the equatorial Ekman layer

    NASA Astrophysics Data System (ADS)

    Marcotte, Florence; Dormy, Emmanuel; Soward, Andrew

    2016-09-01

    The steady incompressible viscous flow in the wide gap between spheres rotating about a common axis at slightly different rates (small Ekman number E) has a long and celebrated history. The problem is relevant to the dynamics of geophysical and planetary core flows, for which, in the case of electrically conducting fluids, the possible operation of a dynamo is of considerable interest. A comprehensive asymptotic study, in the limit E<<1, was undertaken by Stewartson (J. Fluid Mech. 1966, vol. 26, pp. 131-144). The mainstream flow, exterior to the E^{1/2} Ekman layers on the inner/outer boundaries and the shear layer on the inner sphere tangent cylinder C, is geostrophic. Stewartson identified a complicated nested layer structure on C, which comprises relatively thick quasi-geostrophic E^{2/7} (inside C) and E^{1/4} (outside C) layers. They embed a thinner E^{1/3} ageostrophic shear layer (on C), which merges with the inner sphere Ekman layer to form the E^{2/5} Equatorial Ekman layer of axial length E^{1/5}. Under appropriate scaling, this $E^{2/5}$--layer problem may be formulated, correct to leading order, independent of E. Accordingly, the Ekman boundary layer and ageostrophic shear layer become features of the far-field (as identified by the large value of the scaled axial co-ordinate z) solution. We present a numerical solution, which uses a non-local integral boundary condition at finite $z$ to account for the far-field behaviour. Adopting z^{-1} as a small parameter we extend Stewartson's similarity solution for the ageostrophic shear layer to higher orders. This far-field solution agrees well with that obtained from our numerical model.

  3. Advanced double layer capacitors

    NASA Technical Reports Server (NTRS)

    Sarangapani, S.; Lessner, P.; Forchione, J.; Laconti, A. B.

    1989-01-01

    There is a need for large amounts of power to be delivered rapidly in a number of airborne and space systems. Conventional, portable power sources, such as batteries, are not suited to delivering high peak power pulses. The charge stored at the electrode-electrolyte double layer is, however, much more assessible on a short time scale. Devices exploiting this concept were fabricated using carbon and metal oxides (Pinnacle Research) as the electrodes and sulfuric acid as the electrolyte. The approach reported, replaces the liquid sulfuric acid electrolyte with a solid ionomer electrolyte. The challenge is to form a solid electrode-solid ionomer electrolyte composite which has a high capacitance per geometric area. The approach to maximize contact between the electrode particles and the ionomer was to impregnate the electrode particles using a liquid ionomer solution and to bond the solvent-free structure to a solid ionomer membrane. Ruthenium dioxide is the electrode material used. Three strategies are being pursued to provide for a high area electrode-ionomer contact: mixing of the RuOx with a small volume of ionomer solution followed by filtration to remove the solvent, and impregnation of the ionomer into an already formed RuOx electrode. RuOx powder and electrodes were examined by non-electrochemical techniques. X-ray diffraction has shown that the material is almost pure RuO2. The electrode structure depends on the processing technique used to introduce the Nafion. Impregnated electrodes have Nafion concentrated near the surface. Electrodes prepared by the evaporation method show large aggregates of crystals surrounded by Nafion.

  4. Photodiode arrays having minimized cross-talk between diodes

    DOEpatents

    Guckel, Henry; McNamara, Shamus P.

    2000-10-17

    Photodiode arrays are formed with close diode-to-diode spacing and minimized cross-talk between diodes in the array by isolating the diodes from one another with trenches that are formed between the photodiodes in the array. The photodiodes are formed of spaced regions in a base layer, each spaced region having an impurity type opposite to that of the base layer to define a p-n junction between the spaced regions and the base layer. The base layer meets a substrate at a boundary, with the substrate being much more heavily doped than the base layer with the same impurity type. The trenches extend through the base layer and preferably into the substrate. Minority carriers generated by absorption of light photons in the base layer can only migrate to an adjacent photodiode through the substrate. The lifetime and the corresponding diffusion length of the minority carriers in the substrate is very short so that all minority carriers recombine in the substrate before reaching an adjacent photodiode.

  5. Epitaxially grown polycrystalline silicon thin-film solar cells on solid-phase crystallised seed layers

    NASA Astrophysics Data System (ADS)

    Li, Wei; Varlamov, Sergey; Xue, Chaowei

    2014-09-01

    This paper presents the fabrication of poly-Si thin film solar cells on glass substrates using seed layer approach. The solid-phase crystallised P-doped seed layer is not only used as the crystalline template for the epitaxial growth but also as the emitter for the solar cell structure. This paper investigates two important factors, surface cleaning and intragrain defects elimination for the seed layer, which can greatly influence the epitaxial grown solar cell performance. Shorter incubation and crystallisation time is observed using a simplified RCA cleaning than the other two wet chemical cleaning methods, indicating a cleaner seed layer surface is achieved. Cross sectional transmission microscope images confirm a crystallographic transferal of information from the simplified RCA cleaned seed layer into the epi-layer. RTA for the SPC seed layer can effectively eliminate the intragrain defects in the seed layer and improve structural quality of both of the seed layer and the epi-layer. Consequently, epitaxial grown poly-Si solar cell on the RTA treated seed layer shows better solar cell efficiency, Voc and Jsc than the one on the seed layer without RTA treatment.

  6. Direct simulation of high-speed mixing layers

    NASA Technical Reports Server (NTRS)

    Mukunda, H. S.; Sekar, B.; Carpenter, M. H.; Drummond, J. Philip; Kumar, Ajay

    1992-01-01

    A computational study of a nonreacting high-speed mixing layer is performed. A higher order algorithm with sufficient grid points is used to resolve all relevant scales. In all cases, a temporal free-stream disturbance is introduced. The resulting flow is time-sampled to generate a statistical cross section of the flow properties. The studies are conducted at two convective Mach numbers, three free-stream turbulence intensities, three Reynolds numbers, and two types of initial profiles-hyperbolic tangent (tanh) and boundary layer. The boundary-layer profile leads to more realistic predictions of the transition processes. The predicted transition Reynolds number of 0.18 x 10(exp 6) compares well with experimental data. Normalized vortex spacings for the boundary-layer case are about 3.5 and compare favorably with the 1.5 to 2.5 found in experimental measurements. The tanh profile produces spacings of about 10. The growth rate of the layer is shown to be moderately affected by the initial disturbance field, but comparison with experimental data shows moderate agreement. For the boundary-layer case, it is shown that noise at the Strouhal number of 0.007 is selectively amplified and shows little Reynolds number dependence.

  7. The compressible Gortler problem in two-dimensional boundary layers

    NASA Astrophysics Data System (ADS)

    Dando, Andrew H.; Seddougui, Sharon O.

    1993-01-01

    In this paper the authors investigate the growth rates of Gortler vortices in a compressible flow in the inviscid limit of large Gortler number. Numerical solutions are obtained for O(1) wavenumbers. The further limits of (i) large Mach number and (ii) large wavenumber with O(1) Mach number are considered. It is shown that two different types of disturbance mode can appear in this problem. The first is a wall layer mode, so named as it has its eigenfunctions trapped in a thin layer near the wall. The other mode investigated is confined to a thin layer away from the wall and termed a trapped-layer mode for large wavenumbers and an adjustment-layer mode for large Mach numbers, since then this mode has its eigenfunctions concentrated in the temperature adjustment layer. It is possible to investigate the near crossing of the modes which occurs in each of the limits mentioned. The inviscid limit does not predict a fastest growing mode, but does enable a most dangerous mode to be identified for O(1) Mach number. For hypersonic flow the most dangerous mode depends on the size of the Gortler number.

  8. Magnetic noise measurements using cross-correlated Hall sensor arrays

    NASA Astrophysics Data System (ADS)

    Jung, G.; Ocio, M.; Paltiel, Y.; Shtrikman, H.; Zeldov, E.

    2001-01-01

    An experimental technique for measuring magnetic fluctuations by means of a double-layer Hall sensor array is described. The technique relies on cross-correlating Hall signals from two independent sensors positioned one above the other in two separate two-dimensional-electron-gas layers of a GaAs/AlGaAs heterostructure. The effectiveness of the technique is demonstrated by a reduction of the magnitude of the background noise floor of the correlated sensors with respect to the noise level of the best single sensor.

  9. Tuning nanoscale viscoelasticity of polyelectrolyte complexes with multiple types of cross-links

    NASA Astrophysics Data System (ADS)

    Ma, Tianzhu; Han, Biao; Lee, Daeyeon; Han, Lin

    Mechanical properties of hydrogels are manifestation of cross-link type and density, fixed charges and water-polymer interactions. In this study, we revealed how different types of cross-links regulate the nanoscale viscoelasticity of polyelectrolyte networks. Ionically cross-linked PAH/PAA layer-by-layer complexes were modified to include covalent cross-links using EDC. AFM-nanoindentation and force relaxation were performed at various ionic strength (0.01-1M) and pH (1.5-5.5). As-assembled networks, held only by ionic cross-links, underwent >95% relaxation, dominated by cross-link breaking and re-formation. Addition of covalent cross-links increased the instantaneous modulus by 1.6-fold and attenuated relaxation to ~80% of net neutral states (pH >=3.5), as covalent cross-links provide additional elastic components. The network remained stabilized when all ionic cross-links were dissociated at pH <=1.5, whereby further attenuation to 31% in relaxation could be due to viscoelastic polymer conformational changes and fluid flow-induced poroelasticity. Taken together, this study demonstrates the potential of using multiple cross-linking types to tune the viscoelastic mechanisms in polyelectrolyte complexes.

  10. Proanthocyanidins Rapidly Stabilize the Demineralized Dentin Layer

    PubMed Central

    Liu, Y.; Dusevich, V.; Wang, Y.

    2013-01-01

    While proanthocyanidins (PA) are effective in improving collagen’s resistance to collagenolytic degradation, the direct incorporation of PA into an adhesive system is detrimental to the light-curing thereof. Conversely, the use of PA as a primer could circumvent this issue, but little is known about the efficacy of PA in stabilizing collagen when applied in a clinically relevant manner. This study investigated the pre- and post-digestion morphology of an acid-etched dentin collagen layer that underwent PA treatment for time periods on a scale of seconds. The null hypothesis, that there is no difference between the PA-treated and untreated control group, had to be rejected, since it was revealed that the untreated control could not survive 1 hr of exogenous collagenase digestion, while the PA-treated collagen could sustain at least 16 hrs of digestion with no perceptible changes in collagen structure. In addition, the stabilizing effect of the gold-standard cross-linker glutaraldehyde at comparable experimental conditions was found to be almost non-existent within the 5, 15, or 30 sec of cross-linking permitted. Therefore, PA have been proven to be extraordinarily efficient in stabilizing demineralized dentin collagen against enzymatic challenges in a clinically relevant setting, likely due to the non-covalent nature of their interaction with collagen molecules. PMID:23723381

  11. Uncertainty Analysis of Air Radiation for Lunar Return Shock Layers

    NASA Technical Reports Server (NTRS)

    Kleb, Bil; Johnston, Christopher O.

    2008-01-01

    By leveraging a new uncertainty markup technique, two risk analysis methods are used to compute the uncertainty of lunar-return shock layer radiation predicted by the High temperature Aerothermodynamic Radiation Algorithm (HARA). The effects of epistemic uncertainty, or uncertainty due to a lack of knowledge, is considered for the following modeling parameters: atomic line oscillator strengths, atomic line Stark broadening widths, atomic photoionization cross sections, negative ion photodetachment cross sections, molecular bands oscillator strengths, and electron impact excitation rates. First, a simplified shock layer problem consisting of two constant-property equilibrium layers is considered. The results of this simplified problem show that the atomic nitrogen oscillator strengths and Stark broadening widths in both the vacuum ultraviolet and infrared spectral regions, along with the negative ion continuum, are the dominant uncertainty contributors. Next, three variable property stagnation-line shock layer cases are analyzed: a typical lunar return case and two Fire II cases. For the near-equilibrium lunar return and Fire 1643-second cases, the resulting uncertainties are very similar to the simplified case. Conversely, the relatively nonequilibrium 1636-second case shows significantly larger influence from electron impact excitation rates of both atoms and molecules. For all cases, the total uncertainty in radiative heat flux to the wall due to epistemic uncertainty in modeling parameters is 30% as opposed to the erroneously-small uncertainty levels (plus or minus 6%) found when treating model parameter uncertainties as aleatory (due to chance) instead of epistemic (due to lack of knowledge).

  12. Midlatitude sporadic-E layers

    NASA Technical Reports Server (NTRS)

    Miller, K. L.; Smith, L. G.

    1976-01-01

    The partially transparent echo from midlatitude sporadic E layers was recorded by ionosondes between the blanketing frequency and the maximum frequency. The theory that the midlatitude sporadic E layers are not uniform in the horizontal plane but contain localized regions of high electron density was evaluated using data obtained by incoherent scatter radar and found to provide a satisfactory explanation. The main features of midlatitude sporadic E layers are consistent with the convergence of metallic ions as described by the wind shear theory applied to gravity waves and tides. The interference of gravity waves with other gravity waves and tides can be recognized in the altitudes of occurrence and the structure of the layers. Small scale horizontal irregularities are attributed in some cases to critical level effects and in others to fluid instabilities. The convergence of a meteor trail can, under some circumstances, account for localized enhancement of the electron density in the layer.

  13. Fragmentation of drying paint layers

    NASA Astrophysics Data System (ADS)

    Bakos, Katinka; Dombi, András; Járai-Szabó, Ferenc; Néda, Zoltán

    2013-11-01

    Fragmentation of thin layers of drying granular materials on a frictional surface are studied both by experiments and computer simulations. Besides a qualitative description of the fragmentation phenomenon, the dependence of the average fragment size as a function of the layer thickness is thoroughly investigated. Experiments are done using a special nail polish, which forms characteristic crack structures during drying. In order to control the layer thickness, we diluted the nail polish in acetone and evaporated in a controlled manner different volumes of this solution on glass surfaces. During the evaporation process we managed to get an instable paint layer, which formed cracks as it dried out. In order to understand the obtained structures a previously developed spring-block model was implemented in a three-dimensional version. The experimental and simulation results proved to be in excellent qualitative and quantitative agreement. An earlier suggested scaling relation between the average fragment size and the layer thickness is reconfirmed.

  14. Lear jet boundary layer/shear layer laser propagation experiments

    NASA Technical Reports Server (NTRS)

    Gilbert, K.

    1980-01-01

    Optical degradations of aircraft turbulent boundary layers with shear layers generated by aerodynamic fences are analyzed. A collimated 2.5 cm diameter helium-neon laser (0.63 microns) traversed the approximate 5 cm thick natural aircraft boundary layer in double pass via a reflective airfoil. In addition, several flights examined shear layer-induced optical degradation. Flight altitudes ranged from 1.5 to 12 km, while Mach numbers were varied from 0.3 to 0.8. Average line spread function (LSF) and Modulation Transfer Function (MTF) data were obtained by averaging a large number of tilt-removed curves. Fourier transforming the resulting average MTF yields an LSF, thus affording a direct comparison of the two optical measurements. Agreement was good for the aerodynamic fence arrangement, but only fair in the case of a turbulent boundary layer. Values of phase variance inferred from the LSF instrument for a single pass through the random flow and corrected for a large aperture ranged from 0.08 to 0.11 waves (lambda = .63 microns) for the boundary layer. Corresponding values for the fence vary from 0.08 to 0.16 waves. Extrapolation of these values to 10.6 microns suggests negligible degradation for a CO2 laser transmitted through a 5 cm thick, subsonic turbulent boundary layer.

  15. Charged layer with undulated surface: configuration of electrical double layer.

    PubMed

    Lin, Sung-Hwa

    2010-06-15

    A charged layer with undulated surface exists commonly in natural entities (for example the biological membrane layer and the surface of charged colloid) and in artificial fabrications (for example the peripheral surface of ion-exchange membrane pores). When the micro- or nano-scale charged layer systems are concerned, the effect of undulation of charged layer surface on the electrical phenomenon may become great significant. In this work, using the perturbation method, the significance of undulated surface on a charged layer in the electrical phenomenon is investigated. Under assumptions that the undulation amplitude is small and that the Debye-Huckel approximation is applicable, the electrical potential field in three regions is solved simultaneously. Based on the analytical results it is found that, if compared with that in condition of flat surface, the undulation of charged layer surface decreases/increases the magnitude of electrical potential field near the wave crest/trough, due to the curvature of undulated surface. In addition, the surface potential on the undulated surface shows a wavelike distribution. The analytical results also show that, the significance of undulated surface is determined by the physical parameters, including the geometry of undulated surface, the amplitude and the period of undulation, and the fixed charge density in charged layer.

  16. Development of cross-hatch grid morphology and its effect on ordering growth of quantum dots

    NASA Astrophysics Data System (ADS)

    Zhang, C. L.; Xu, B.; Wang, Z. G.; Jin, P.; Zhao, F. A.

    2005-01-01

    We investigate the development of cross-hatch grid surface morphology in growing mismatched layers and its effect on ordering growth of quantum dots (QDs). For a 60° dislocation (MD), the effective part in strain relaxation is the part with the Burgers vector parallel to the film/substrate interface within its b⇀edge component; so the surface stress over a MD is asymmetric. When the strained layer is relatively thin, the surface morphology is cross-hatch grid with asymmetric ridges and valleys. When the strained layer is relatively thick, the ridges become nearly symmetrical, and the dislocations and the ridges inclined-aligned. In the following growth of InAs, QDs prefer to nucleate on top of the ridges. By selecting ultra-thin In0.15Ga0.85As layer (50 nm) and controlling the QDs layer at just formed QDs, we obtained ordered InAs QDs.

  17. The fine structure of the front side magnetopause during two successive crossings

    NASA Technical Reports Server (NTRS)

    Formisano, V.; Pedersen, A.; Lindqvist, P.-A.

    1982-01-01

    The magnetopause crossings of November 10, 1977, which are considered to be representative of a class of structures, are investigated, and a procedure is developed to derive approximate surface currents near the magnetopause from ISEE 1 magnetic field data by assuming a constant speed of the magnetopause along its normal for each crossing of the magnetopause layer. Changes in the magnetic field indicate that current sheets exist on each side of the magnetopause layer, which is characterized by an irregular magnetic field and a magnetosheath-like energy distribution. No boundary layer plasma is observed on the magnetospheric field lines inside the magnetopause, and electromagnetic energy is found to be dissipated at the two edges of the magnetopause layer where the current layers are observed.

  18. Understanding Molecular Interactions within Chemically Selective Layered Polymer Assemblies

    SciTech Connect

    Gary J. Blanchard

    2009-06-30

    This work focuses on two broad issues. These are (1) the molecular origin of the chemical selectivity achieved with ultrathin polymer multilayers, and (2) how the viscoelastic properties of the polymer layers are affected by exposure to solvent and analytes. These issues are inter-related, and to understand them we need to design experiments that probe both the energetic and kinetic aspects of interfacial adsorption processes. This project focuses on controling the chemical structure, thickness, morphology and sequential ordering of polymer layers bound to interfaces using maleimide-vinyl ether and closely related alternating copolymerization chemistry and efficient covalent cross-linking reactions that allow for layer-by-layer polymer deposition. This chemistry has been developed during the funding cycle of this Grant. We have measure the equilibrium constants for interactions between specific layers within the polymer interfaces and size-controlled, surface-functionalized gold nanoparticles. The ability to control both size and functionality of gold nanoparticle model analytes allows us to evaluate the average “pore size” that characterizes our polymer films. We have measured the “bulk” viscosity and shear modulus of the ultrathin polymer films as a function of solvent overlayer identity using quartz crystal microbalance complex impedance measurements. We have measured microscopic viscosity at specific locations within the layered polymer interfaces with time-resolved fluorescence lifetime and depolarization techniques. We combine polymer, cross-linking and nanoparticle synthetic expertise with a host of characterization techniques, including QCM gravimetry and complex impedance analysis, steady state and time-resolved spectroscopies.

  19. Borax mediated layer-by-layer self-assembly of neutral poly(vinyl alcohol) and chitosan.

    PubMed

    Manna, Uttam; Patil, Satish

    2009-07-01

    We report a multilayer film of poly(vinyl alcohol) (PVA)-borate complex and chitosan by using a layer-by-layer approach. PVA is an uncharged polymer, but hydroxyl functional groups of PVA can be cross-linked by using borax as a cross-linking agent. As a result electrostatic charges and intra- and interchain cross-links are introduced in the PVA chain and provide physically cross-linked networks. The PVA-borate was then deposited on a flat substrate as well as on colloidal particles with chitosan as an oppositely charged polyelectrolyte. Quartz crystal microbalance, scanning electron microscopy, and atomic force microscopy were used to follow the growth of thin film on flat substrate. Analogous experiments were performed on melamine formaldehyde colloidal particles (3-3.5 microm) to quantify the process for the preparation of hollow microcapsules. Removal of the core in 0.1 N HCl results in hollow microcapsules. Characterization of microcapsules by transmission electron microscopy revealed formation of stable microcapsules. Further, self-assembly of PVA-borate/chitosan was loaded with the anticancer drug doxorubicin, and release rates were determined at different pH values to highlight the drug delivery potential of this system.

  20. Layer-by-layer synthesis of metal-containing conducting polymers: caged metal centers for interlayer charge transport.

    PubMed

    Liu, Wenjun; Huang, Weijie; Pink, Maren; Lee, Dongwhan

    2010-09-01

    Metal-templated [2 + 3]-type cocondensation of a pi-extended boronic acid and nioxime furnished a series of cage molecules, which were electropolymerized to prepare metal-containing conducting polymers (MCPs). Despite sharing essentially isostructural organic scaffolds, these materials display metal-dependent electrochemical properties as evidenced by different redox windows observed for M = Co, Fe, Ru. Consecutive electropolymerization using two different monomers furnished bilayer MCPs having different metals in each layer. In addition to functioning as heavy atom markers in cross-sectional analysis by FIB and EDX, redox-active metal centers participate in voltage-dependent interlayer electron transport to give rise to cyclic voltammograms that are distinctively different from those of each layer alone or random copolymers. A simple electrochemical technique can thus be used as a straightforward diagnostic tool to investigate the structural ordering of electrically conductive layered materials. PMID:20690667

  1. Electric-field-induced layer-by-layer fabrication of inorganic-organic hybrid second-order nonlinear optical films.

    PubMed

    Wang, Shiwei; Zhao, Lisha; Zhang, Xiaolong; Shi, Zuosen; Cui, Zhanchen; Yang, Yanqiang

    2009-08-15

    This work focused on the development of a novel method for molecular level assembly and processing of inorganic-organic hybrid second-order nonlinear optical (SONLO) multilayer films. Aromatic diazo group linked silicon sol was first synthesized and used as a polycation. This oligomer was assembled into inorganic-organic hybrid SONLO multilayer films by electric-field-induced layer-by-layer assembly technique with a low molecular weight chromophore molecule as an anion. After UV irradiation, the electrostatic interaction between layers converted to covalent bonds. Large second-harmonic generation signal of the assembled film was observed, which confirmed that the chromophore in the film had a high degree of molecular orientation as assembled under the electric field. As the cross-linked structure and silicon oxygen meshwork in the films, the resulting inorganic-organic hybrid multilayer films displayed good thermal and chemical stability, and excellent NLO properties. PMID:19433327

  2. Caution -- Beam Crossing Ahead

    SciTech Connect

    Barat, Kenneth L.

    2008-04-02

    There are times when a laser beam needs to cross between tables or even go from one room to another. This presents an interesting traffic-flow and safety challenge to both the laser safety officer and laser user. Fortunately it is a challenge that has several solutions But the simplest solution may not be the best one. For example, the simplest way to get a beam from one optical table to another is just to put a sturdy tube around it. That's a permanent solution, and it completely contains the laser beam. While this is laser safe, there can be egress issues if it blocks a walkway. One comment this author often hears is, 'We can just duck under the tube.' The fire marshal, as well as the laser safety officer, might have issues with this. Especially in the case of a darkened lab, a blocked walkway can present a hazard of its own. One good solution is to transport the beam from Point A to Point B through a fiberoptic cable, when that is possible. One should easily be able to run the fiber up and over any walkway or down through a conduit on the floor. An important concern often overlooked with fibers is a label at the termination end indicating disconnection may expose one to laser radiation. Suppose there's an experiment that is usually confined to a single optical table, but sometimes needs to expand to a second table. It's inconvenient to install a permanent tube between the tables, so some sort of temporary arrangement is desirable. I have often seen people casually lay a beam tube across support arms, and remove it when it's not needed. The problem with this approach is that there's no mechanism to prevent the beam from crossing if somebody's forgotten the tube, or if the tube gets knocked out of place. A better solution is a mechanism that only allows the beam to cross when the beam protection is in place. A swing shutter, or a guillotine and swing arm, are examples (Figures 1 and 2). Another alternative is a sensor, maybe a little microswitch, that activates a

  3. Cross-Cutting Relationships

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 25 August 2003

    The several linear cross-cutting grabens and collapse features observed in this THEMIS image illustrate the relative timing of a series of complex geologic processes as more recent events produce features that overlap and intersect older ones. Some impact craters are observed to be cut grabens, suggesting an older impact event compared to impact craters that appear fresh and unmodified.

    Image information: VIS instrument. Latitude 14.1, Longitude 236.3 East (123.7 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  4. Layers Exposed at Polar Canyon

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This false-color subframe of an image from the High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter shows the north polar layered deposits at top and darker materials at bottom, exposed in a scarp at the head of Chasma Boreale, a large canyon eroded into the layered deposits.

    The polar layered deposits appear red because of dust mixed within them, but are ice-rich as indicated by previous observations. Water ice in the layered deposits is probably responsible for the pattern of fractures seen near the top of the scarp. The darker material below the layered deposits may have been deposited as sand dunes, as indicated by the crossbedding (truncation of curved lines) seen near the middle of the scarp. It appears that brighter, ice-rich layers were deposited between the dark dunes in places. Exposures such as these are useful in understanding recent climate variations that are likely recorded in the polar layered deposits.

    NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.

  5. Temperature synchronized molecular layer epitaxy

    NASA Astrophysics Data System (ADS)

    Kurabayashi, T.; Nishizawa, J.

    1994-12-01

    This paper reports the first results on a modified molecular layer epitaxy (MLE) technique to deposit epitaxial GaAs films by changing the substrate temperature for alternate TEG (or TMG) and AsH 3 injection. This method of temperature synchronized molecular layer epitaxy (TSMLE) is a new concept for MLE and atomic layer epitaxy (ALE). The growth rates and the doping phenomena showed different characteristics to the conventional methods which were performed at a constant temperature. This method was effective not only for the study of monolayer growth, but also for device application, especially for the heavily doped p-type layer of which carrier concentration is 10 20 cm -3 order. Carbon doped p-type layer was achieved by TMG-AsH 3 TSMLE. The carbon concentration increased by decreasing the temperature during AsH 3 injection and by increasing the temperature during TMG injection. Zn-doped layer was achieved by TEG-AsH 3 TSMLE using DEZn as a dopant gas for p-type layer fabrication. To doped heavily, DEZn injected after AsH 3 injection and the temperature during AsH 3 injection had a suitable value at 393°C.

  6. D0 layer 0 innermost layer of silicon microstrip tracker

    SciTech Connect

    Hanagaki, K.; /Fermilab

    2006-01-01

    A new inner layer silicon strip detector has been built and will be installed in the existing silicon microstrip tracker in D0. They report on the motivation, design, and performance of this new detector.

  7. The role of nonlinear critical layers in boundary layer transition

    NASA Technical Reports Server (NTRS)

    Goldstein, M.E.

    1995-01-01

    Asymptotic methods are used to describe the nonlinear self-interaction between pairs of oblique instability modes that eventually develops when initially linear spatially growing instability waves evolve downstream in nominally two-dimensional laminar boundary layers. The first nonlinear reaction takes place locally within a so-called 'critical layer', with the flow outside this layer consisting of a locally parallel mean flow plus a pair of oblique instability waves - which may or may not be accompanied by an associated plane wave. The amplitudes of these waves, which are completely determined by nonlinear effects within the critical layer, satisfy either a single integro-differential equation or a pair of integro-differential equations with quadratic to quartic-type nonlinearities. The physical implications of these equations are discussed.

  8. Layer-by-layer-assembled healable antifouling films.

    PubMed

    Chen, Dongdong; Wu, Mingda; Li, Bochao; Ren, Kefeng; Cheng, Zhongkai; Ji, Jian; Li, Yang; Sun, Junqi

    2015-10-21

    Healable antifouling films are fabricated by the exponential layer-by-layer assembly of PEGylated branched poly(ethylenimine) and hyaluronic acid followed by post-crosslinking. The antifouling function originates from the grafted PEG and the extremely soft nature of the films. The rapid and multiple healing of damaged antifouling functions caused by cuts and scratches can be readily achieved by immersing the films in normal saline solution. PMID:26455733

  9. DNA release dynamics from bioreducible layer-by-layer films

    PubMed Central

    Blacklock, Jenifer; Mao, Guangzhao; Oupický, David; Möhwald, Helmuth

    2010-01-01

    DNA release dynamics from layer-by-layer (LbL) films is an important aspect to consider with regards to localized gene delivery systems. The rate of DNA release and the condensation state of DNA during release are of particular interest in the field of gene delivery. A hyperbranched poly(amido amine) (RHB) containing bioreducible disulfide bonds is used to form interpolyelectrolyte complexes with DNA during LbL film assembly. During films disassembly, DNA is released in physiologic conditions due to the reducing nature of the RHB. Uncondensed DNA deposited on the surface was compared to DNA condensed by RHB in polyplex form by using two types of LbL films, RHB/DNA/RHB and polyplex terminated films, RHB/DNA/polyplex. LbL films with up to three layers are used in order to facilitate high-resolution AFM imaging. X-ray reflectivity, ellipsometry, and Fourier transform infrared spectroscopy are also used. The film disassembly, rearrangement and release of molecules from the surface due to thiol-disulfide exchange is conducted in reducing dithiothreitol (DTT) solutions. Salt is found to accelerate the overall rate of film disassembly. Additionally, it was found that the polyplex layer disassembles faster than the DNA layer. The predominant intermediate structure is the toroid structure for the polyplex layer and the fiber bundle structure for the DNA layer during film disassembly. This study offers a simple means to modulate DNA release from LbL films by utilizing both condensed and uncondensed DNA in different layers. The study highlights nanostructures, toroids and bundles, as dominant intermediate DNA structures during the DNA release from LbL films. PMID:20131916

  10. On Multiple-Layered Vortices

    NASA Technical Reports Server (NTRS)

    Rossow, Vernon J.

    2011-01-01

    As part of an ongoing effort to find ways to make vortex flow fields decompose more quickly, photographs and observations are presented of vortex flow fields that indicate the presence of multiple layers of fluid rotating about a common axis. A survey of the literature indicates that multiple-layered vortices form in waterspouts, tornadoes and lift-generated vortices of aircraft. An explanation for the appearance of multiple-layered structures in vortices is suggested. The observations and data presented are intended to improve the understanding of the formation and persistence of vortex flow fields.

  11. On the origin of rhythmic layering in layered gabbros

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Zhang, J.

    2015-12-01

    Rhythmic layering of silicates (plagioclase, pyroxene and olivine), ilmenite and magnitite is a common feature in mafic-ultramafic intrusions. The origin of rhythmic layering has been hotly debated in the literatures. Proposed mechanisms include gravity differentiation, double-diffusive convection, oscillatory crystallization of magma, repeated injection and supplement of magma, etc. Here we provide detailed FTIR and EBSD studies on the water content and deformation microstructure of gabbros from the Panzhihua intrusion and experimentally deformed synthetic gabrros and magnetite aggregates with a volume ratio of 6:4. The FTIR analyses revealed a significant amount of hydroxyls in both clinopyroxene (411-775 ppm) and plagioclase (328-716 ppm), suggesting a high water content mantle plume source. The EBSD analyses show similar fabrics in constitutent minerals of natural and experimental specimens: a weak clinopyroxene fabric of (100) parallel to foliation and [001] parallel to lineation; a strong plagioclase fabric of (010) parallel to foliation and [100] parallel to lineation, a weak ilmenite fabric of (001) parallel to foliation and [hk0] parallel to lieantion; and a near random magnitite fabric. There is an obvious rhythmic layering in sheared gabrros and magnetite aggregates similar to natural observations. Our results revealed strong layer-parallel shearing deformation during the formation of the Panxi layered intructions. There is a significant strength contrast between gabbro and Fe-Ti oxides. We propose that the formation of the rhythmic layering in mafic-ultramafic intrusions is caused mainly by rheological stratification of Fe-Ti oxides and gabbros.

  12. Radar cross section of insects

    NASA Astrophysics Data System (ADS)

    Riley, J. R.

    1985-02-01

    X-band measurements of radar cross section as a function of the angle between insect body axis and the plane of polarization are presented. A finding of particular interest is that in larger insects, maximum cross section occurs when the E-vector is perpendicular to the body axis. A new range of measurements on small insects (aphids, and planthoppers) is also described, and a comprehensive summary of insect cross-section data at X-band is given.

  13. Interaction of railway vehicles with track in cross-winds

    NASA Astrophysics Data System (ADS)

    Xu, Y. L.; Ding, Q. S.

    2006-04-01

    This paper presents a framework for simulating railway vehicle and track interaction in cross-wind. Each 4-axle vehicle in a train is modeled by a 27-degree-of-freedom dynamic system. Two parallel rails of a track are modeled as two continuous beams supported by a discrete-elastic foundation of three layers with sleepers and ballasts included. The vehicle subsystem and the track subsystem are coupled through contacts between wheels and rails based on contact theory. Vertical and lateral rail irregularities simulated using an inverse Fourier transform are also taken into consideration. The simulation of steady and unsteady aerodynamic forces on a moving railway vehicle in cross-wind is then discussed in the time domain. The Hilber Hughes Taylor α-method is employed to solve the nonlinear equations of motion of coupled vehicle and track systems in cross-wind. The proposed framework is finally applied to a railway vehicle running on a straight track substructure in cross-wind. The safety and comfort performance of the moving vehicle in cross-wind are discussed. The results demonstrate that the proposed framework and the associated computer program can be used to investigate interaction problems of railway vehicles with track in cross-wind.

  14. Inversion layer MOS solar cells

    NASA Technical Reports Server (NTRS)

    Ho, Fat Duen

    1986-01-01

    Inversion layer (IL) Metal Oxide Semiconductor (MOS) solar cells were fabricated. The fabrication technique and problems are discussed. A plan for modeling IL cells is presented. Future work in this area is addressed.

  15. Boundary Layer Control on Airfoils.

    ERIC Educational Resources Information Center

    Gerhab, George; Eastlake, Charles

    1991-01-01

    A phenomena, boundary layer control (BLC), produced when visualizing the fluidlike flow of air is described. The use of BLC in modifying aerodynamic characteristics of airfoils, race cars, and boats is discussed. (KR)

  16. Intermetallic Layers in Soldered Joints

    1998-12-10

    ILAG solves the one-dimensional partial differential equations describing the multiphase, multicomponent, solid-state diffusion-controlled growth of intermetallic layers in soldered joints. This software provides an analysis capability for materials researchers to examine intermetallic growth mechanisms in a wide variety of defense and commercial applications involving both traditional and advanced materials. ILAG calculates the interface positions of the layers, as well as the spatial distribution of constituent mass fractions, and outputs the results at user-prescribed simulation times.

  17. Removing Boundary Layer by Suction

    NASA Technical Reports Server (NTRS)

    Ackeret, J

    1927-01-01

    Through the utilization of the "Magnus effect" on the Flettner rotor ship, the attention of the public has been directed to the underlying physical principle. It has been found that the Prandtl boundary-layer theory furnishes a satisfactory explanation of the observed phenomena. The present article deals with the prevention of this separation or detachment of the flow by drawing the boundary layer into the inside of a body through a slot or slots in its surface.

  18. Modeling the urban boundary layer

    NASA Technical Reports Server (NTRS)

    Bergstrom, R. W., Jr.

    1976-01-01

    A summary and evaluation is given of the Workshop on Modeling the Urban Boundary Layer; held in Las Vegas on May 5, 1975. Edited summaries from each of the session chairpersons are also given. The sessions were: (1) formulation and solution techniques, (2) K-theory versus higher order closure, (3) surface heat and moisture balance, (4) initialization and boundary problems, (5) nocturnal boundary layer, and (6) verification of models.

  19. (abstract) Cross with Your Spectra? Cross-Correlate Instead!

    NASA Technical Reports Server (NTRS)

    Beer, Reinhard

    1994-01-01

    The use of cross-correlation for certain types of spectral analysis is discussed. Under certain circumstances, the use of cross-correlation between a real spectrum and either a model or another spectrum can provide a very powerful tool for spectral analysis. The method (and its limitations) will be described with concrete examples using ATMOS data.

  20. Simulation of auroral double layers

    NASA Technical Reports Server (NTRS)

    Hubbard, R. F.; Joyce, G.

    1979-01-01

    Some basic properties of plasma double layers are deduced from a particle-in-cell computer simulation and related to parallel electric-field structures above the auroral regions. The simulation results on the processes leading to double-layer formation are examined, particularly in relation to the transient stage and double-layer structure and stability. It is concluded that: (1) a large potential difference applied to a finite-length plasma will be concentrated in a shocklike localized region instead of occurring over the entire length of the system; (2) the initial stage in double-layer formation is dominated by a large-potential pulse propagating in the direction of the induced electrostatic drift; (3) the entire potential is dropped over a specific scale length once the double layer has formed; and (4) this scale length is expected to be of the order of 1 km for a double layer above a discrete auroral arc with a potential of 10 kV and the electric-field vector parallel to the magnetic-field vector.

  1. Double layers above the aurora

    NASA Technical Reports Server (NTRS)

    Temerin, M.; Mozer, F. S.

    1987-01-01

    Two different kinds of double layers were found in association with auroral precipitation. One of these is the so-called electrostatic shock, which is oriented at an oblique angle to the magnetic field in such a way that the perpendicular electric field is much larger than the parallel electric field. This type of double layer is often found at the edges of regions of upflowing ion beams and the direction of the electric fields in the shock points toward the ion beam. The potential drop through the shock can be several kV and is comparable to the total potential needed to produce auroral acceleration. Instabilities associated with the shock may generate obliquely propagating Alfven waves, which may accelerate electrons to produce flickering auroras. The flickering aurora provides evidence that the electrostatic shock may have large temporal fluctuations. The other kind of double layer is the small-amplitude double layer found in regions of upward flowing in beams, often in association with electrostatic ion cyclotron waves. The parallel and perpendicular electric fields in these structures are comparable in magnitude. The associated potentials are a few eV. Since many such double layers are found in regions of upward flowing ion beams, the combined potential drop through a set of these double layers can be substantial.

  2. Planar shock wave sliding over a water layer

    NASA Astrophysics Data System (ADS)

    Rodriguez, V.; Jourdan, G.; Marty, A.; Allou, A.; Parisse, J.-D.

    2016-08-01

    In this work, we conduct experiments to study the interaction between a horizontal free water layer and a planar shock wave that is sliding over it. Experiments are performed at atmospheric pressure in a shock tube with a square cross section (200× 200 mm^2) for depths of 10, 20, and 30 mm; a 1500-mm-long water layer; and two incident planar shock waves having Mach numbers of 1.11 and 1.43. We record the pressure histories and high-speed visualizations to study the flow patterns, surface waves, and spray layers behind the shock wave. We observe two different flow patterns with ripples formed at the air-water interface for the weaker shock wave and the dispersion of a droplet mist for the stronger shock wave. From the pressure signals, we extract the delay time between the arrival of the compression wave into water and the shock wave in air at the same location. We show that the delay time evolves with the distance traveled over the water layer, the depth of the water layer, and the Mach number of the shock wave.

  3. Crossed Cerebellar Diaschisis

    PubMed Central

    Han, Shuguang; Wang, Xiaopeng; Xu, Kai; Hu, Chunfeng

    2016-01-01

    Abstract Crossed cerebellar diaschisis (CCD) describes a depression of oxidative metabolism glucose and blood flow in the cerebellum secondary to a supratentorial lesion in the contralateral cerebral hemisphere. PET/MR has the potential to become a powerful tool for demonstrating and imaging intracranial lesions .We herein report 3 cases of CCD imaging using a tri-modality PET/CT–MR set-up for investigating the value of adding MRI rather than CT to PET in clinical routine. We describe 3 patients with CCD and neurological symptoms in conjunction with abnormal cerebral fluorodeoxyglucose (FDG) positron emission tomography/computed tomography-magnetic resonance imaging (PET/CT–MR) manifestations including arterial spin-labeling (ASL) and T2-weighted images. In all, 18FDG-PET/CT detected positive FDG uptake in supratentorial lesions, and hypometabolism with atrophy in the contralateral cerebellum. More than that, hybrid PET/MRI provided a more accurate anatomic localization and ASL indicated disruption of the cortico-ponto-cerebellar pathway. Using pathology or long-term clinical follow-up to confirm the PET and ASL findings, the supratentorial lesions of the 3 patients were respectively diagnosed with cerebral infarction, recurrent glioma, and metastasis. The reports emphasize the significance of multimodality radiological examinations. Multimodality imaging contributes to proper diagnosis, management, and follow-up of supratentorial lesions with CCD. PMID:26765477

  4. Ultrathin Molecular-Layer-by-Layer Polyamide Membranes: Insights from Atomistic Molecular Simulations.

    PubMed

    Liyana-Arachchi, Thilanga P; Sturnfield, James F; Colina, Coray M

    2016-09-01

    In this study, we present an atomistic simulation study of several physicochemical properties of polyamide (PA) membranes formed from interfacial polymerization or from a molecular-layer-by-layer (mLbL) on a silicon wafer. These membranes are composed of meta-phenylenediamine (MPD) and benzene-1,3,5-tricarboxylic acid chloride (TMC) for potential reverse osmosis (RO) applications. The mLbL membrane generation procedure and the force field models were validated, by comparison with available experimental data, for hydrated density, membrane swelling, and pore size distributions of PA membranes formed by interfacial polymerization. Physicochemical properties such as density, free volume, thickness, the degree of cross-linking, atomic compositions, and average molecular orientation (which is relevant for the mLbL membranes) are compared for these different processes. The mLbL membranes are investigated systematically with respect to TMC monomer growth rate per substrate surface area, MPD/TMC ratio, and the number of mLbL deposition cycles. Atomistic simulations show that the mLbL deposition generates membranes with a constant film growth if both the TMC monomer growth rate and MPD/TMC monomer ratio are kept constant. The film growth rate increases with TMC monomer growth rate or MPD/TMC ratio. Furthermore, it was found on one hand that the mLbL membrane density and free volume varies significantly with respect to the TMC monomer growth rate, while on the other hand the degree of cross-linking and the atomic composition varies considerably with the MPD/TMC ratio. Additionally, it was found that both TMC and MPD orient at a tilted angle with respect to the substrate surface, where their angular distribution and average angle orientation depend on both the TMC growth rate and the number of deposition cycles. This study illustrates that molecular simulations can play a crucial role in the understanding of structural properties that can empower the design of the next

  5. Ultrathin Molecular-Layer-by-Layer Polyamide Membranes: Insights from Atomistic Molecular Simulations.

    PubMed

    Liyana-Arachchi, Thilanga P; Sturnfield, James F; Colina, Coray M

    2016-09-01

    In this study, we present an atomistic simulation study of several physicochemical properties of polyamide (PA) membranes formed from interfacial polymerization or from a molecular-layer-by-layer (mLbL) on a silicon wafer. These membranes are composed of meta-phenylenediamine (MPD) and benzene-1,3,5-tricarboxylic acid chloride (TMC) for potential reverse osmosis (RO) applications. The mLbL membrane generation procedure and the force field models were validated, by comparison with available experimental data, for hydrated density, membrane swelling, and pore size distributions of PA membranes formed by interfacial polymerization. Physicochemical properties such as density, free volume, thickness, the degree of cross-linking, atomic compositions, and average molecular orientation (which is relevant for the mLbL membranes) are compared for these different processes. The mLbL membranes are investigated systematically with respect to TMC monomer growth rate per substrate surface area, MPD/TMC ratio, and the number of mLbL deposition cycles. Atomistic simulations show that the mLbL deposition generates membranes with a constant film growth if both the TMC monomer growth rate and MPD/TMC monomer ratio are kept constant. The film growth rate increases with TMC monomer growth rate or MPD/TMC ratio. Furthermore, it was found on one hand that the mLbL membrane density and free volume varies significantly with respect to the TMC monomer growth rate, while on the other hand the degree of cross-linking and the atomic composition varies considerably with the MPD/TMC ratio. Additionally, it was found that both TMC and MPD orient at a tilted angle with respect to the substrate surface, where their angular distribution and average angle orientation depend on both the TMC growth rate and the number of deposition cycles. This study illustrates that molecular simulations can play a crucial role in the understanding of structural properties that can empower the design of the next

  6. Characterization of silicon-germanium epitaxial layer by photoluminescence intensity and reflectance measurement techniques.

    PubMed

    Back, Dohyun; Lee, Jaehyeong

    2014-12-01

    Si(1-x)Ge(x) epitaxial layers with various Ge fractions sample were characterized by photoluminescence intensity method at room temperature. Photoluminescence intensity was affected by minority carrier lifetime, defect density, and surface condition. PL intensity profile showed misfit dislocation on epitaxial layer for 15%, 21%, 24%, and 26%, since dislocations were one of minority carrier lifetime degradation parameters. It clearly showed misfit dislocation profiles, cross-hatch, and PL intensity was low at dislocation region.

  7. In Situ Boundary Layer Coral Metabolism in the Atlantic Ocean Acidification Test Bed

    NASA Astrophysics Data System (ADS)

    McGillis, Wade

    2013-04-01

    and Chris Langdon, Brice Loose, Dwight Gledhill, Diana Hsueh, Derek Manzello, Ian Enochs, Ryan Moyer We present net ecosystem productivity (nep) and net ecosystem calcification (nec) in coral and seagrass ecosystems using the boundary layer gradient flux technique (CROSS). Coastal anthropogenic inputs and changes in global ocean chemistry in response to rising levels of atmospheric carbon dioxide has emerged in recent years as a topic of considerable concern. Coral reefs are particularly vulnerable from eroded environmental conditions including ocean acidification and water pollution. The Atlantic Ocean Acidification Testbed (AOAT) project monitors metabolism to ascertain the continuing health of coral reef ecosystems. The CROSS boundary layer nep/nec approach is one component of this diagnostic program. Certification of CROSS as an operational monitoring tool is underway in the AOAT. CROSS inspects a benthic community and measures productivity/respiration and calcification/dissolution over an area of 10 square meters. Being a boundary layer tool, advection and complex mesoscale flows are not a factor or concern and CROSS is autonomous and can be used at deep benthic sites. The interrogation area is not enclosed therefore exposed to ambient light, flow, and nutrient levels. CROSS is easy to deploy, unambiguous, and affordable. Repeated measurements have been made from 2011-2012 in reefal systems in La Parguera Puerto Rico and the Florida Keys, USA. Diurnal, seasonal and regional metabolism will be compared and discussed. The ability to accurately probe benthic ecosystems provides a powerful management and research tool to policy makers and researchers.

  8. Boundary Crossing and Boundary Objects

    ERIC Educational Resources Information Center

    Akkerman, Sanne F.; Bakker, Arthur

    2011-01-01

    Diversity and mobility in education and work present a paramount challenge that needs better conceptualization in educational theory. This challenge has been addressed by educational scholars with the notion of "boundaries", particularly by the concepts of "boundary crossing" and "boundary objects". Although studies on boundary crossing and…

  9. XCOM: Photon Cross Sections Database

    National Institute of Standards and Technology Data Gateway

    SRD 8 XCOM: Photon Cross Sections Database (Web, free access)   A web database is provided which can be used to calculate photon cross sections for scattering, photoelectric absorption and pair production, as well as total attenuation coefficients, for any element, compound or mixture (Z <= 100) at energies from 1 keV to 100 GeV.

  10. Cross-Country Skiing Today.

    ERIC Educational Resources Information Center

    Caldwell, John

    This book presents changes in cross country skiing which have taken place in the last several years and is directed toward both beginning and seasoned tour skiers. Discussed are the following topics: (1) the cross-country revolution (new fiberglass skis); (2) equipment (how to choose from the new waxless touring skis); (3) care of equipment; (4)…

  11. Housatonic crossing tests the technology

    SciTech Connect

    Garrett, L.D. )

    1992-06-01

    One of the early problems facing engineers planning the construction of the Iroquois Gas Transmission System, from the Canadian border through six Northeastern states, was how and where to cross the major rivers and Long Island Sound. The Housatonic River, a major waterway near Shelton, Conn., had been crossed earlier during a previous pipeline project. The earlier crossing had been installed by conventional open cutting. However, the state of Connecticut and its environmental agencies insisted that the Iroquois crossing must be installed by horizontal directional drilling. This paper reports that prior to completing the design of the Housatonic River crossing, Iroquois Gas engineers took several deep soil borings at three possible crossing sites. Each site showed the same thing: a hard schist rock with compression strengths from 2,760 psi to 16,500 psi, overlain by either recent fill or alluvial till. Although most of the river crossing would be drilled through the hard rock formation, the drilled path would certainly have to cross the transition zones of fill or till on both sides of the river.

  12. Hybrid window layer for photovoltaic cells

    DOEpatents

    Deng, Xunming; Liao, Xianbo; Du, Wenhui

    2011-10-04

    A novel photovoltaic solar cell and method of making the same are disclosed. The solar cell includes: at least one absorber layer which could either be a lightly doped layer or an undoped layer, and at least a doped window-layers which comprise at least two sub-window-layers. The first sub-window-layer, which is next to the absorber-layer, is deposited to form desirable junction with the absorber-layer. The second sub-window-layer, which is next to the first sub-window-layer, but not in direct contact with the absorber-layer, is deposited in order to have transmission higher than the first-sub-window-layer.

  13. Hybrid window layer for photovoltaic cells

    DOEpatents

    Deng, Xunming; Liao, Xianbo; Du, Wenhui

    2011-02-01

    A novel photovoltaic solar cell and method of making the same are disclosed. The solar cell includes: at least one absorber layer which could either be a lightly doped layer or an undoped layer, and at least a doped window-layers which comprise at least two sub-window-layers. The first sub-window-layer, which is next to the absorber-layer, is deposited to form desirable junction with the absorber-layer. The second sub-window-layer, which is next to the first sub-window-layer, but not in direct contact with the absorber-layer, is deposited in order to have transmission higher than the first-sub-window-layer.

  14. Hybrid window layer for photovoltaic cells

    DOEpatents

    Deng, Xunming

    2010-02-23

    A novel photovoltaic solar cell and method of making the same are disclosed. The solar cell includes: at least one absorber layer which could either be a lightly doped layer or an undoped layer, and at least a doped window-layers which comprise at least two sub-window-layers. The first sub-window-layer, which is next to the absorber-layer, is deposited to form desirable junction with the absorber-layer. The second sub-window-layer, which is next to the first sub-window-layer, but not in direct contact with the absorber-layer, is deposited in order to have transmission higher than the first-sub-window-layer.

  15. Layer-by-layer assembly of vertically conducting graphene devices.

    PubMed

    Chen, Jing-Jing; Meng, Jie; Zhou, Yang-Bo; Wu, Han-Chun; Bie, Ya-Qing; Liao, Zhi-Min; Yu, Da-Peng

    2013-01-01

    Graphene has various potential applications owing to its unique electronic, optical, mechanical and chemical properties, which are primarily based on its two-dimensional nature. Graphene-based vertical devices can extend the investigations and potential applications range to three dimensions, while interfacial properties are crucial for the function and performance of such graphene vertical devices. Here we report a general method to construct graphene vertical devices with controllable functions via choosing different interfaces between graphene and other materials. Two types of vertically conducting devices are demonstrated: graphene stacks sandwiched between two Au micro-strips, and between two Co layers. The Au|graphene|Au junctions exhibit large magnetoresistance with ratios up to 400% at room temperature, which have potential applications in magnetic field sensors. The Co|graphene|Co junctions display a robust spin valve effect at room temperature. The layer-by-layer assembly of graphene offers a new route for graphene vertical structures. PMID:23715280

  16. Surface molecular imprinting in layer-by-layer films on silica particles.

    PubMed

    Gauczinski, Jan; Liu, Zhihua; Zhang, Xi; Schönhoff, Monika

    2012-03-01

    An improvement to molecular imprinting in polymers, where bulk systems often suffer from slow dynamics of release and uptake, is the formation of thin films with imprinting sites that are more rapid to access by guest molecules. Based on our previous development of surface molecular imprinting layer-by-layer (LbL) films (SMILbL), the present paper presents selective imprinted sites in a surface film on dispersed silica particles, thus designing a SMILbL system with maximized active area and in addition allowing studies with bulk techniques. The multilayer is designed to include the template during the LbL buildup and to form a cross-linked network upon UV-irradiation for enhanced stability. A theophylline moiety is grafted to poly(acrylic acid) as the template, while a UV-sensitive diazo polycation cross-links the polymers after irradiation. Electrophoretic measurements prove the successful buildup of the multilayers by an alternating sign of the zeta potential. Template release is achieved by cleavage of the grafted template. The released amount of template is quantified in solution by (1)H NMR spectra and is in good agreement with the prediction from surface coverage calculations. Rebinding studies of template to the now empty imprinted binding sites show a high affinity for a theophylline derivative with a rebound amount on the order of the original template content. In contrast to theophylline, caffeine with a very similar chemical structure-only differing in one functional group-shows very different binding properties due to a thiol moiety in the binding site. Thus, a particle system with very selective molecular imprinting sites is demonstrated. PMID:22324368

  17. Combining hydrogen-bonding complexation in solution and hydrogen-bonding-directed layer-by-layer assembly for the controlled loading of a small organic molecule into multilayer films.

    PubMed

    Zeng, Guanghong; Gao, Jian; Chen, Senlin; Chen, Huan; Wang, Zhiqiang; Zhang, Xi

    2007-11-01

    We have combined hydrogen-bonding complexation in solution and layer-by-layer assembly for the controlled loading of a water-insoluble small organic molecule, bis-triazine (DTA), an azobenzene derivative containing multiple hydrogen bond donors and acceptors, into layer-by-layer multilayer films of poly(acrylic acid) and diazo-resin. UV-visible spectroscopy indicates that DTA has been loaded into multilayer films, with the loading amount increasing linearly with the number of layers. The loading amount can be well tuned either by changing the concentration of DTA or the solvent composition at the complexation step. Fourier transform infrared spectroscopy has revealed that both the complexation and layer-by-layer assembly are driven by hydrogen bonding. After photo-cross-linking and immersion in dimethyl sulfoxide to release DTA, the film can serve as an absorbent for DTA. This study provides a new unconventional layer-by-layer assembly that combines hydrogen-bonding complexation in solution and hydrogen-bond-driven layer-by-layer assembly at the interface. This method provides a new route to load a variety of water-insoluble functional organic molecules into layer-by-layer films. PMID:17915899

  18. Cross-flow vortex structure and transition measurements using multi-element hot films

    NASA Technical Reports Server (NTRS)

    Agarwal, Naval K.; Mangalam, Siva M.; Maddalon, Dal V.; Collier, Fayette S., Jr.

    1991-01-01

    An experiment on a 45-degree swept wing was conducted to study three-dimensional boundary-layer characteristics using surface-mounted, micro-thin, multi-element hot-film sensors. Cross-flow vortex structure and boundary-layer transition were measured from the simultaneously acquired signals of the hot films. Spanwise variation of the root-mean-square (RMS) hot-film signal show a local minima and maxima. The distance between two minima corresponds to the stationary cross-flow vortex wavelength and agrees with naphthalene flow-visualization results. The chordwise and spanwise variation of amplified traveling (nonstationary) cross-flow disturbance characteristics were measured as Reynolds number was varied. The frequency of the most amplified cross-flow disturbances agrees with linear stability theory.

  19. Physics of magnetospheric boundary layers

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.

    1995-01-01

    This final report was concerned with the ideas that: (1) magnetospheric boundary layers link disparate regions of the magnetosphere-solar wind system together; and (2) global behavior of the magnetosphere can be understood only by understanding its internal linking mechanisms and those with the solar wind. The research project involved simultaneous research on the global-, meso-, and micro-scale physics of the magnetosphere and its boundary layers, which included the bow shock, the magnetosheath, the plasma sheet boundary layer, and the ionosphere. Analytic, numerical, and simulation projects were performed on these subjects, as well as comparisons of theoretical results with observational data. Other related activity included in the research included: (1) prediction of geomagnetic activity; (2) global MHD (magnetohydrodynamic) simulations; (3) Alfven resonance heating; and (4) Critical Ionization Velocity (CIV) effect. In the appendixes are list of personnel involved, list of papers published; and reprints or photocopies of papers produced for this report.

  20. 'Blueberry' Layers Indicate Watery Origins

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This microscopic image, taken at the outcrop region dubbed 'El Capitan' near the Mars Exploration Rover Opportunity's landing site, reveals millimeter-scale (.04 inch-scale) layers in the lower portion. This same layering is hinted at by the fine notches that run horizontally across the sphere-like grain or 'blueberry' in the center left. The thin layers do not appear to deform around the blueberry, indicating that these geologic features are concretions and not impact spherules or ejected volcanic material called lapilli. Concretions are balls of minerals that form in pre-existing wet sediments. This image was taken by the rover's microscopic imager on the 29th martian day, or sol, of its mission. The observed area is about 3 centimeters (1.2 inches) across.

  1. North Polar Layers in Summer

    NASA Technical Reports Server (NTRS)

    2004-01-01

    15 October 2004 It is now early summer in the northern hemisphere on Mars, and this means that the ices of the north polar cap are in full retreat. Exposed from beneath seasonal frost are the eroded layers of what Mars scientists suspect are composed of a mixture of dust and ice (and in some layers, sand). This October 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the north polar layers exposed on a moderately-dipping slope. The bright material at the top of the image is water ice frost; the triangular features are thought to be caused by wind erosion of the frost. This image is located near 87.1oN, 267.4oW, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  2. Lidar study of K layer

    NASA Astrophysics Data System (ADS)

    Jiao, Jing

    2016-07-01

    A double-laser-beam lidar was successfully developed in 2010 to measure the K layer over Yanqing County, Beijing (40.5°N, 116.2°E). Comprehensive statistical analyses of sporadic K (Ks) layer parameters were conducted using two years of lidar data, and the parameters of the Ks layers and their distribution obtained by the analyses are described. The seasonal distribution of Ks occurrence was obtained, with two maxima observed in January and July, respectively. The seasonal distributions of sporadic E (Es) occurrence over Beijing differ from those of Ks occurrence. However, good correlations between Es and Ks in case by case study were found. We also found that four Ks events with peak altitudes lower than 90 km were associated with large and sharp temperature increases in five comparative examples.

  3. Layered Rocks in 'Columbia Hills'

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This black-and-white image shows the first layered rocks scientists have seen close up in Gusev Crater, where NASA's Mars Exploration Rover Spirit landed Jan. 4, 2004. While Spirit's twin rover, Opportunity, reached the stadium-size Endurance Crater on the other side of Mars and began exploring its many layered outcrops in early May, Spirit traveled more than 3.5 kilometers (2.2 miles) to get to this layered bedrock in the 'Columbia Hills.' Scientists are planning to conduct a study of these rocks to determine if they are volcanic or sedimentary in origin, and if they have been chemically altered. Spirit's panoramic camera took this image on sol 217 (Aug. 13, 2004).

  4. Unsteady turbulent boundary layer analysis

    NASA Technical Reports Server (NTRS)

    Singleton, R. E.; Nash, J. F.; Carl, L. W.; Patel, V. C.

    1973-01-01

    The governing equations for an unsteady turbulent boundary layer on a swept infinite cylinder, composed of a continuity equation, a pair of momentum equations and a pair of turbulent energy equations which include upstream history efforts, are solved numerically. An explicit finite difference analog to the partial differential equations is formulated and developed into a computer program. Calculations were made for a variety of unsteady flows in both two and three dimensions but primarily for two dimensional flow fields in order to first understand some of the fundamental physical aspects of unsteady turbulent boundary layers. Oscillating free stream flows without pressure gradient, oscillating retarded free stream flows and monotonically time-varying flows have all been studied for a wide frequency range. It was found that to the lowest frequency considered, the lower frequency bound being determined by economic considerations (machine time), there were significant unsteady effects on the turbulent boundary layer.

  5. The surface location of individual residues in a bacterial S-layer protein.

    PubMed

    Kinns, Helen; Howorka, Stefan

    2008-03-21

    Bacterial surface layer (S-layer) proteins self-assemble into large two-dimensional crystalline lattices that form the outermost cell-wall component of all archaea and many eubacteria. Despite being a large class of self-assembling proteins, little is known about their molecular architecture. We investigated the S-layer protein SbsB from Geobacillus stearothermophilus PV72/p2 to identify residues located at the subunit-subunit interface and to determine the S-layer's topology. Twenty-three single cysteine mutants, which were previously mapped to the surface of the SbsB monomer, were subjected to a cross-linking screen using the photoactivatable, sulfhydryl-reactive reagent N-[4-(p-azidosalicylamido)butyl]-3'-(2'-pyridyldithio)propionamide. Gel electrophoretic analysis on the formation of cross-linked dimers indicated that 8 out of the 23 residues were located at the interface. In combination with surface accessibility data for the assembled protein, 10 residues were assigned to positions at the inner, cell-wall-facing lattice surface, while 5 residues were mapped to the outer, ambient-exposed lattice surface. In addition, the cross-linking screen identified six positions of intramolecular cross-linking within the assembled protein but not in the monomeric S-layer protein. Most likely, these intramolecular cross-links result from conformational changes upon self-assembly. The results are an important step toward the further structural elucidation of the S-layer protein via, for example, X-ray crystallography and cryo-electron microscopy. Our approach of identifying the surface location of residues is relevant to other planar supramolecular protein assemblies. PMID:18262545

  6. Experimental studies on the stability and transition of 3-dimensional boundary layers

    NASA Technical Reports Server (NTRS)

    Nitschke-Kowsky, P.

    1987-01-01

    Three-dimensional unstable boundary layers were investigated as to their characteristic instabilities, leading to turbulence. Standing cross-flow instabilities and traveling waves preceding the transition were visualized with the hydrogen bubble technique in the boundary layer above the wall of a swept cylinder. With the sublimation method and hot film technique, a model consisting of a swept flat plate with a pressure-inducing displacement body in the 1 m wind tunnel was studied. Standing waves and traveling waves in a broad frequency are observed. The boundary layer of this model is close to the assumptions of the theory.

  7. Multilayer structured polymer light emitting diodes with cross-linked polymer matrices

    NASA Astrophysics Data System (ADS)

    Zhou, Zhang-Lin; Sheng, Xia; Nauka, K.; Zhao, Lihua; Gibson, Gary; Lam, Sity; Yang, Chung Ching; Brug, James; Elder, Rich

    2010-01-01

    Currently, there is great interest in manufacturing multilayer polymer light emitting diode (PLED) structures via low-cost solution-based spin-casting or printing methods. The difficulty with this approach is that solvent from freshly deposited films often dissolves the underlying layers. This letter demonstrates that fully operational multilayer PLED structures can be fabricated via a solution process by embedding the hole transport material in cross-linked inert polymer matrices that protect the functional material while subsequent layers are deposited using the same solvent. The resulting devices exhibited greatly improved quantum efficiency compared with devices that did not employ cross-linked polymer matrices.

  8. Controlled Layer-by-Layer Etching of MoS₂.

    PubMed

    Lin, TaiZhe; Kang, BaoTao; Jeon, MinHwan; Huffman, Craig; Jeon, JeaHoo; Lee, SungJoo; Han, Wei; Lee, JinYong; Lee, SeHan; Yeom, GeunYoung; Kim, KyongNam

    2015-07-29

    Two-dimensional (2D) metal dichalcogenides like molybdenum disulfide (MoS2) may provide a pathway to high-mobility channel materials that are needed for beyond-complementary metal-oxide-semiconductor (CMOS) devices. Controlling the thickness of these materials at the atomic level will be a key factor in the future development of MoS2 devices. In this study, we propose a layer-by-layer removal of MoS2 using the atomic layer etching (ALET) that is composed of the cyclic processing of chlorine (Cl)-radical adsorption and argon (Ar)(+) ion-beam desorption. MoS2 etching was not observed with only the Cl-radical adsorption or low-energy (<20 eV) Ar(+) ion-beam desorption steps; however, the use of sequential etching that is composed of the Cl-radical adsorption step and a subsequent Ar(+) ion-beam desorption step resulted in the complete etching of one monolayer of MoS2. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) indicated the removal of one monolayer of MoS2 with each ALET cycle; therefore, the number of MoS2 layers could be precisely controlled by using this cyclical etch method. In addition, no noticeable damage or etch residue was observed on the exposed MoS2.

  9. The Entrainment Interface Layer of Stratocumulus-topped Boundary Layers

    NASA Astrophysics Data System (ADS)

    Krueger, S.; Hill, S.

    2010-09-01

    The entrainment interface layer (EIL) is the layer between cloud top and the free atmosphere. It contains mixtures of air from the cloud layer and the free atmosphere. In addition to turbulent mixing, phase changes and radiative heating or ccoling also affect the thermodynamic properties of air in the EIL. Eventually, air from the EIL is entrained into the cloud layer. How do processes in the EIL affect the entrainment rate? What is the structure of the EIL? Is cloud-top an interface (a region of high gradients), or simply an iso-surface? We are using airborne measuurements taken in the EIL during POST (Physics of Stratocumulus Top), which took place during July and August 2008 near Monterey, California, USA, to address these questions. High-rate measurements of temperature and liquid water content made just 0.5 m apart allow us to perform a high-resolution analysis of a conserved variable (liquid water potential temperature). When combined with lower-rate measurements of water vapor, they also allow us to perform a mixture fraction analysis following vanZanten and Duynkerke (2002).

  10. Cross-Linking Poly(lactic acid) Film Surface by Neutral Hyperthermal Hydrogen Molecule Bombardment.

    PubMed

    Du, Wangli; Shao, Hong; He, Zhoukun; Tang, Changyu; Liu, Yu; Shen, Tao; Zhu, Yan; Lau, Woon-ming; Hui, David

    2015-12-16

    Constructing a dense cross-linking layer on a polymer film surface is a good way to improve the water resistance of poly(lactic acid) (PLA). However, conventional plasma treatments have failed to achieve the aim as a result of the unavoidable surface damage arising from the charged species caused by the uncontrolled high energy coming from colliding ions and electrons. In this work, we report a modified plasma method called hyperthermal hydrogen-induced cross-linking (HHIC) technology to construct a dense cross-linking layer on PLA film surfaces. This method produces energy-controlled neutral hyperthermal hydrogen, which selectively cleaves C-H bonds by molecule collision from the PLA film without breaking other bonds (e.g., C-C bonds in the polymer backbone), and results in subsequent cross-linking of the carbon radicals generated from the organic molecules. The formation of a dense cross-linking layer can serve as a barrier layer to significantly improve both the hydrophobicity and water vapor barrier property of the PLA film. Because of the advantage of selective cleavage of C-H bonds by HHIC treatment, the original physical properties (e.g., mechanical strength and light transmittance) of the PLA films are well-preserved. PMID:26594874

  11. Cross-Linking Poly(lactic acid) Film Surface by Neutral Hyperthermal Hydrogen Molecule Bombardment.

    PubMed

    Du, Wangli; Shao, Hong; He, Zhoukun; Tang, Changyu; Liu, Yu; Shen, Tao; Zhu, Yan; Lau, Woon-ming; Hui, David

    2015-12-16

    Constructing a dense cross-linking layer on a polymer film surface is a good way to improve the water resistance of poly(lactic acid) (PLA). However, conventional plasma treatments have failed to achieve the aim as a result of the unavoidable surface damage arising from the charged species caused by the uncontrolled high energy coming from colliding ions and electrons. In this work, we report a modified plasma method called hyperthermal hydrogen-induced cross-linking (HHIC) technology to construct a dense cross-linking layer on PLA film surfaces. This method produces energy-controlled neutral hyperthermal hydrogen, which selectively cleaves C-H bonds by molecule collision from the PLA film without breaking other bonds (e.g., C-C bonds in the polymer backbone), and results in subsequent cross-linking of the carbon radicals generated from the organic molecules. The formation of a dense cross-linking layer can serve as a barrier layer to significantly improve both the hydrophobicity and water vapor barrier property of the PLA film. Because of the advantage of selective cleavage of C-H bonds by HHIC treatment, the original physical properties (e.g., mechanical strength and light transmittance) of the PLA films are well-preserved.

  12. Hemoglobin protein hollow shells fabricated through covalent layer-by-layer technique

    SciTech Connect

    Duan Li; He Qiang; Cui Yue; Wang Kewei; Li Junbai . E-mail: jbli@iccas.ac.cn

    2007-03-09

    Hemoglobin (Hb) protein microcapsules held together by cross-linker, glutaraldehyde (GA), were successfully fabricated by covalent layer-by-layer (LbL) technique. The Schiff base reaction occurred on the colloid templates between the aldehyde groups of GA and free amino sites of Hb results in the formation of GA/Hb microcapsules after the removal of the templates. The structure of obtained monodisperse protein microcapsule was characterized by transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). The UV-Vis spectra measurements demonstrate the existence of Hb in the assembled capsules. Cyclic voltammetry (CV) and potential-controlled amperometric measurements (I-t curve) confirm that hemoglobin microcapsules after fabrication remain their heme electroactivity. Moreover, direct electron transfer process from protein to electrode surface was performed to detect the heme electrochemistry without using any mediator or promoter. The experiments of fluorescence recovery after photobleaching (FRAP) by CLSM demonstrate that the hemoglobin protein microcapsules have an improved permeability comparing to the conventional polyelectrolyte microcapsules.

  13. Interactions between Chitosan and Alginate Dialdehyde Biopolymers and Their Layer-by-Layer Assemblies.

    PubMed

    Aston, Robyn; Wimalaratne, Medini; Brock, Aidan; Lawrie, Gwendolyn; Grøndahl, Lisbeth

    2015-06-01

    Biopolymers are researched extensively for their applications in biomaterials science and drug delivery including structures and complexes of more than one polymer. Chemical characterization of complexes formed between chitosan (CHI) and alginate dialdehyde (ADA) biopolymers established that while electrostatic interactions dominate (as determined from X-ray photoelectron spectroscopy (XPS)) covalent cross-linking between these biopolymers also contribute to their stability (evidenced from immersion in salt solution). It was furthermore found that imine bond formation could not be directly detected by any of the techniques XPS, FTIR, (1)H NMR, or fluorescence. The layer-by-layer assemblies of the biopolymers formed on silica colloids, glass slides, and alginate hydrogel beads were evaluated using XPS, as well as zeta potential measurements for the silica colloids and changes to hydration properties for the hydrogels. It was found that the degree of oxidation of ADA affected the LbL assemblies in terms of a greater degree of CHI penetration observed when using the more conformationally flexible biopolymer ADA (higher degree of oxidation).

  14. Layer-by-Layer Surface Molecular Imprinting on Polyacrylonitrile Nanofiber Mats.

    PubMed

    Liu, Yuxuan; Cao, Bing; Jia, Peng; An, Junhu; Luo, Chao; Ma, Lijing; Chang, Jiao; Pan, Kai

    2015-06-25

    Surface molecular imprinting in layer-by-layer (SMI-LbL) film is known as a facile and effective strategy to build imprinting sites that are more accessible to template molecules compared with molecular imprinting in polymers. Herein, we accomplished the formation of SMI-LbL film on electrospun nanofibers for the first time. The SMI-LbL nanofibers were prepared by a template-induced LbL process on the polyacrylonitrile (PAN) nanofiber substrates, followed by postinfiltrating and photo-cross-linking of photosensitive agent 4,4'-diazostilbene-2,2'-disulfonic acid disodium salt (DAS). The obtained nanofiber mat maintained the nanofibrous structure and showed rapid absorption and extraction of template molecules of meso-tetra(4-carboxyphenyl)-porphine (Por). The binding capacity of Por reached 2.1 mg/g when 3.5 bilayers were deposited on the nanofibers. After six cycles of extraction and reabsorption, the binding capacity of Por remained at 83%. Moreover, the absorption results of the targeted templated molecule of Por and the control molecule of Fast Green, which had a very similar chemical structure and charge status to Por, indicated the specific absorption for template molecule of Por. Thus, a surface molecular imprinted nanofiber mat with high selectivity of the templated molecule has been demonstrated. PMID:26038802

  15. Operating System Abstraction Layer (OSAL)

    NASA Technical Reports Server (NTRS)

    Yanchik, Nicholas J.

    2007-01-01

    This viewgraph presentation reviews the concept of the Operating System Abstraction Layer (OSAL) and its benefits. The OSAL is A small layer of software that allows programs to run on many different operating systems and hardware platforms It runs independent of the underlying OS & hardware and it is self-contained. The benefits of OSAL are that it removes dependencies from any one operating system, promotes portable, reusable flight software. It allows for Core Flight software (FSW) to be built for multiple processors and operating systems. The presentation discusses the functionality, the various OSAL releases, and describes the specifications.

  16. Multi-walled carbon nanotubes with rectangular or square cross-section

    NASA Astrophysics Data System (ADS)

    Mizutani, Kanako; Kohno, Hideo

    2016-06-01

    Multi-walled carbon nanotubes with rectangular or square cross-section are formed. The nanotubes are about 50-200 nm in width, and their walls are around 5-30 nm thick. It is very likely that the rectangular cross-section is shaped simultaneously when nanotubes are formed from catalyst Fe nanoparticles during chemical vapor deposition process, and the shape is stabilized by the bonding between adjoining graphene layers in the multi-walled structure.

  17. Investigation of three-dimensional shock wave boundary layer interactions. A flowfield model of the glancing shock/turbulent boundary layer interaction

    NASA Astrophysics Data System (ADS)

    Kubota, H.

    1980-01-01

    Three-dimensional glancing-shock/turbulent boundary-layer interaction has been investigated at the Cranfield Institute of Technology in two separate test programmes using a 2.5 x 2.5 inch intermittent tunnel and a 9 x 9 inch continuous tunnel, at a Mach number of approximately 2.5. The experimental results include oil-flow pictures, vapour-screen photographs, surface static pressure distributions, local heat transfers, liquid crystal pictures of surface temperature, and viscous layer surveys. The test data indicate that the interaction region consists of two different viscous flows, the side-wall boundary layer and an induced layer originating near the shock generator root and crossing the path of the side-wall boundary layer. In this flow field model, no flow separation appears as long as the surface stream lines of the side-wall boundary layer can be pliable enough to be bent along the edge of the induced layer, even when the surface-flow deflection exceeds the shock angle. However, an ordinary separation does take place when the induced layer forces the surface stream lines to deflect beyond a maximum permissible angle.

  18. Three-dimensional image reconstruction of insect flight muscle. I. The rigor myac layer

    PubMed Central

    1989-01-01

    We have obtained detailed three-dimensional images of in situ cross- bridge structure in insect flight muscle by electron microscopy of multiple tilt views of single filament layers in ultrathin sections, supplemented with data from thick sections. In this report, we describe the images obtained of the myac layer, a 25-nm longitudinal section containing a single layer of alternating myosin and actin filaments. The reconstruction reveals averaged rigor cross-bridges that clearly separate into two classes constituting lead and rear chevrons within each 38.7-nm axial repeat. These two classes differ in tilt angle, size and shape, density, and slew. This new reconstruction confirms our earlier interpretation of the lead bridge as a two-headed cross-bridge and the rear bridge as a single-headed cross-bridge. The importance of complementing tilt series with additional projections outside the goniometer tilt range is demonstrated by comparison with our earlier myac layer reconstruction. Incorporation of this additional data reveals new details of rigor cross-bridge structure in situ which include clear delineation of (a) a triangular shape for the lead bridge, (b) a smaller size for the rear bridge, and (c) density continuity across the thin filament in the lead bridge. Within actin's regular 38.7-nm helical repeat, local twist variations in the thin filament that correlate with the two cross-bridge classes persist in this new reconstruction. These observations show that in situ rigor cross-bridges are not uniform, and suggest three different myosin head conformations in rigor. PMID:2768334

  19. The Magnetospheric Sash and the Cross-Tail S

    NASA Astrophysics Data System (ADS)

    White, Willard W.; Siscoe, George L.; Erickson, Gary M.; Kaymaz, Zerefsan; Maynard, Nelson C.; Siebert, Keith D.; Sonnerup, Bengt U. Ö.; Weimer, Daniel R.

    As revealed in MHD simulation, the magnetospheric sash is a band of weak magnetic field that, for the usual case in which the IMF is approximately perpendicular to the geomagnetic dipole, runs tailward along the high-latitude magnetopause flanks from one dayside cusp to the other, closing via the cross-tail neutral sheet. On the magnetopause flanks, it contains the magnetic separator line, at which all three topological types of field lines meet. Seen in a cross-sectional plane through the near-Earth tail, the magnetospheric sash takes the form of the cross-tail S, a weak-field feature comprised of the tail neutral sheet with diagonally symmetric extensions along the magnetopause flanks connecting it to the separator line. The cross-tail S is evident in the MHD results and in cross-sectional maps based on IMP 8 data. The magnetopause expression of the sash is latent in prior works that described the geometry of antiparallel fields across the magnetopause and the consequent cancellation of the fields within the magnetopause layer. The sash picture bears a strong resemblance to antiparallel merging geometry.

  20. Assembly-Controlled Permeability of Layer-by-Layer Polymeric Microcapsules Using a Tapered Fluidized Bed.

    PubMed

    Noi, Ka Fung; Roozmand, Ali; Björnmalm, Mattias; Richardson, Joseph J; Franks, George V; Caruso, Frank

    2015-12-23

    Nano- and microcapsules engineered through layer-by-layer (LbL) assembly are finding an increasingly large number of applications as catalysts, electrochemical biosensors, bioreactors, artificial cells and drug delivery vehicles. While centrifugation-based LbL assembly is the most common method for coating template particles and preparing capsules, it is a batch process and requires frequent intervention that renders the system challenging to automate and scale up. Here, we report the use of a tapered fluidized bed (TFB) for the preparation of multilayered polymer capsules. This is a significant improvement over our recent approach of fluidizing particles in cylindrical fluidized beds (CFB) for LbL assembly. We demonstrate that TFB is compatible with particles <3 μm in diameter (an order-of-magnitude improvement compared with CFB), which can be fluidized with minimal entrainment. Additionally, layering materials were expanded to include both electrostatic and hydrogen-bonding polymer pairs (e.g., poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate) (PSS), and thiol-modified poly(methacrylic acid) (PMASH) and poly(N-vinylpyrrolidone) (PVPON), respectively). Finally, differences between capsules prepared via centrifugation-based and TFB LbL assembly were investigated. The obtained TFB microcapsules demonstrate increased film thickness and roughness compared with those prepared using centrifugation-based LbL assembly. Furthermore, PMASH microcapsules exhibit lower swelling and permeability when prepared via TFB LbL assembly compared with centrifugation-based LbL assembly due to enhanced multilayer deposition, entanglement, and cross-linking. Therefore, polymeric capsules fabricated via TFB LbL assembly may be useful for encapsulation and retention of relatively low molecular weight (∼20 kDa) hydrophilic biomacromolecules to passively or responsively release the payload for drug delivery applications. PMID:26651354

  1. Imaging transient formation of diffusion layers with fluorescence-enabled electrochemical microscopy.

    PubMed

    Oja, Stephen M; Zhang, Bo

    2014-12-16

    Fluorescence-enabled electrochemical microscopy (FEEM) is demonstrated as a new technique to image transient concentration profiles of redox species generated on ultramicroelectrodes (UMEs). FEEM converts an electrical signal into an optical signal by electrically coupling a conventional redox reaction to a fluorogenic reporter reaction on a closed bipolar electrode. We describe the implementation of FEEM for diffusion layer imaging and use an array of thousands of parallel bipolar electrodes to image the diffusion layers of UMEs in two and three dimensions. This new technique provides a way to image an entire 2-dimensional lateral cross section of a dynamic diffusion layer in a single experiment. By taking several of these lateral cross sections at different axial positions in the diffusion layer, a 3-dimensional image of the diffusion layer can be built. We image the diffusion layer of a 10 μm diameter carbon fiber electrode over the course of a cyclic voltammetry experiment and compare the FEEM-generated images to concentration profiles generated from numerical simulation. We also image the diffusion layer of a two electrode array consisting of two 10 μm diameter carbon fibers over the course of a potential step experiment.

  2. The Amphiolite Layers In The Cumulate Gabbros, (Northern-Turkey)

    NASA Astrophysics Data System (ADS)

    Özkan, Mutlu; Faruk Çelik, Ömer; Altıntaş, İsmail Emir; Sherlock, Sarah; Chelle-Michou, Cyril; Marzoli, Andrea; Ulianov, Alexey; Melih Çörtük, Rahmi; Topuz, Gültekin

    2016-04-01

    The Early-Middle Jurassic SSZ type dismembered ophiolite sequence, which is remnants of the Tethyan oceanic lithosphere, crop out in the accretionary complex around Tokat-Çamlıbel region (Northern Turkey). The main lithology of the ophiolite sequence are cumulate gabbros, isotropic gabbros and basalts. The amphibolite layers, which their thickness are up to 2 m, are observed in the cumulate gabbros. In this study, we aim to discuss a possible formation mechanism of the amphibolitic rocks in the cumulate gabbros, based on the field, mineralogical, geochemical and geochronological data. The cumulate gabbros (olivine-gabbro, gabbro-norite and gabbro) have generally well developed magmatic layers and they show cumulate texture. They are cross cut by pegmatite gabbros, dolerites and plagiogranite dikes. In terms of the mechanism of formation, the amphibolite layers in the cumulate gabbros are different from dolerite, pegmatite gabbro and plagiogranite dikes crosscutting the cumulate gabbros. Although the cumulate gabbros, the mafic and felsic dikes have not undergone any metamorphism (except the hydrothermal metamorphism), the amphibolite layers show well developed foliation and banded structure. Moreover, field and petrographic observations showed that the amphibolitic rocks were highly subjected to shearing. The amphibolitic rocks are mainly composed of magnesio-hornblende + plagioclase (andesine), ± biotite and opaque minerals and they exhibit nematoblastic texture. The amphibolite layers in the cumulate gabbros are crosscut by the plagiogranite dikes. The plagiogranites consist mainly of quartz, plagioclase, biotite and opaque minerals and they show granular texture. Undulose extinction and sub-grain formation in quartz minerals indicate to the presence of deformation phase affecting the plagiogranite dikes. LA-ICP-MS dating on zircon from plagiogranite dikes which is cross-cutting of the amphibolite layers, yielded Middle Jurassic ages. 40Ar/39Ar dating of

  3. Comparison of reacting and non-reacting shear layers at a high subsonic Mach number

    NASA Technical Reports Server (NTRS)

    Chang, C. T.; Marek, C. J.; Wey, C.; Jones, R. A.; Smith, M. J.

    1993-01-01

    The flow field in a hydrogen-fueled planar reacting shear layer was measured with an LDV system and is compared with a similar air to air case without combustion. Measurements were made with a speed ratio of 0.34 with the highspeed stream at Mach 0.71. They show that the shear layer with reaction grows faster than one without, and both cases are within the range of data scatter presented by the established database. The coupling between the streamwise and the cross-stream turbulence components inside the shear layer is slow, and reaction only increased it slightly. However, a more organized pattern of the Reynolds stress is present in the reacting shear layer, possibly as a result of larger scale structure formation in the layer associated with heat release.

  4. Synergistic effects of the Lactobacillus acidophilus surface layer and nisin on bacterial growth.

    PubMed

    Prado-Acosta, Mariano; Ruzal, Sandra M; Allievi, Mariana C; Palomino, María Mercedes; Sanchez Rivas, Carmen

    2010-02-01

    We have previously described a murein hydrolase activity for the surface layer (S-layer) of Lactobacillus acidophilus ATCC 4356. Here we show that, in combination with nisin, this S-layer acts synergistically to inhibit the growth of pathogenic Gram-negative Salmonella enterica and potential pathogenic Gram-positive bacteria, Staphylococcus aureus and Bacillus cereus. In addition, bacteriolytic effects were observed for the Gram-positive species tested. We postulate that the S-layer enhances the access of nisin into the cell membrane by enabling it to cross the cell wall, while nisin provides the sudden ion-nonspecific dissipation of the proton motive force required to enhance the S-layer murein hydrolase activity. PMID:19948852

  5. Suppression of cross-hatched polariton disorder in GaAs/AlAs microcavities by strain compensation

    NASA Astrophysics Data System (ADS)

    Zajac, Joanna M.; Clarke, Edmund; Langbein, Wolfgang

    2012-07-01

    Zinc-blende semiconductor heterostructures grown in the [001] direction with a small lattice mismatch accommodate stress by developing a cross-hatch dislocation pattern. In GaAs based planar microcavities grown by molecular beam epitaxy, this pattern creates a potential landscape for exciton-polaritons, causing scattering and localization. We report here on suppressing the cross-hatch by introducing strain-compensating AlP layers into the center of the low index AlAs layers of the distributed Bragg reflectors. We observe a reduction of the cross-hatch dislocation density by at least one order of magnitude for 1.1 nm thick AlP layers, which correspond to an effective AlAs0.985P0.015 low index layer. These compensated structures show a remaining polariton disorder potential in the 10 μeV range.

  6. Thin bacteria/Layered Double Hydroxide films using a layer-by-layer approach.

    PubMed

    Halma, Matilte; Khenifi, Aicha; Sancelme, Martine; Besse-Hoggan, Pascale; Bussière, Pierre-Olivier; Prévot, Vanessa; Mousty, Christine

    2016-07-15

    This paper reports the design of thin bacteria/Layered Double Hydroxides (LDH) films in which bacterial cells of Pseudomonas sp. strain ADP were assembled alternatively with Mg2Al-NO3 LDH nanosheets by a layer-by-layer deposition method. The UV-Vis spectroscopy was used to monitor the assembly process, showing a progressive increase in immobilized bacteria amount upon deposited cycles. The {ADP/LDH}n film was characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy and atomic force microscopy. The metabolic activity of immobilized bacteria was determined using chronoamperometry by measuring the biochemical oxygen demand in presence of glucose using an artificial electron acceptor (Fe(CN)6(3-)) at 0.5V/Ag-AgCl. A steady current of 0.250μAcm(-2) was reached in about 30s after the addition of 5mM glucose. PMID:27124809

  7. Interlayer tunneling in double-layer quantum hall pseudoferromagnets.

    PubMed

    Balents, L; Radzihovsky, L

    2001-02-26

    We show that the interlayer tunneling I-V in double-layer quantum Hall states displays a rich behavior which depends on the relative magnitude of sample size, voltage length scale, current screening, disorder, and thermal lengths. For weak tunneling, we predict a negative differential conductance of a power-law shape crossing over to a sharp zero-bias peak. An in-plane magnetic field splits this zero-bias peak, leading instead to a "derivative" feature at V(B)(B(parallel)) = 2 pi Planck's over 2 pi upsilon B(parallel)d/e phi(0), which gives a direct measurement of the dispersion of the Goldstone mode corresponding to the spontaneous symmetry breaking of the double-layer Hall state. PMID:11290258

  8. Airborne lidar detection of subsurface oceanic scattering layers

    NASA Technical Reports Server (NTRS)

    Hoge, Frank E.; Wright, C. Wayne; Krabill, William B.; Buntzen, Rodney R.; Gilbert, Gary D.

    1988-01-01

    The airborne lidar detection and cross-sectional mapping of submerged oceanic scattering layers are reported. The field experiment was conducted in the Atlantic Ocean southeast of Assateague Island, VA. NASA's Airborne Oceanographic Lidar was operated in the bathymetric mode to acquire on-wavelength 532-nm depth-resolved backscatter signals from shelf/slope waters. Unwanted laser pulse reflection from the air-water interface was minimized by spatial filtering and off-nadir operation. The presence of thermal stratification over the shelf was verified by the deployment of airborne expendable bathythermographs. Optical beam transmission measurements acquired from a surface truthing vessel indicated the presence of a layer of turbid water near the sea floor over the inner portion of the shelf.

  9. 3D Imaging of the OH mesospheric emissive layer

    NASA Astrophysics Data System (ADS)

    Kouahla, M. N.; Moreels, G.; Faivre, M.; Clairemidi, J.; Meriwether, J. W.; Lehmacher, G. A.; Vidal, E.; Veliz, O.

    2010-01-01

    A new and original stereo imaging method is introduced to measure the altitude of the OH nightglow layer and provide a 3D perspective map of the altitude of the layer centroid. Near-IR photographs of the OH layer are taken at two sites separated by a 645 km distance. Each photograph is processed in order to provide a satellite view of the layer. When superposed, the two views present a common diamond-shaped area. Pairs of matched points that correspond to a physical emissive point in the common area are identified in calculating a normalized cross-correlation coefficient (NCC). This method is suitable for obtaining 3D representations in the case of low-contrast objects. An observational campaign was conducted in July 2006 in Peru. The images were taken simultaneously at Cerro Cosmos (12°09‧08.2″ S, 75°33‧49.3″ W, altitude 4630 m) close to Huancayo and Cerro Verde Tellolo (16°33‧17.6″ S, 71°39‧59.4″ W, altitude 2272 m) close to Arequipa. 3D maps of the layer surface were retrieved and compared with pseudo-relief intensity maps of the same region. The mean altitude of the emission barycenter is located at 86.3 km on July 26. Comparable relief wavy features appear in the 3D and intensity maps. It is shown that the vertical amplitude of the wave system varies as exp (Δz/2H) within the altitude range Δz = 83.5-88.0 km, H being the scale height. The oscillatory kinetic energy at the altitude of the OH layer is comprised between 3 × 10-4 and 5.4 × 10-4 J/m3, which is 2-3 times smaller than the values derived from partial radio wave at 52°N latitude.

  10. Layering Literacies and Contemporary Learning

    ERIC Educational Resources Information Center

    Abrams, Sandra Schamroth; Russo, Michael P.

    2015-01-01

    This article explores how adolescents layer literacies in and outside school. Findings from a longitudinal study of gaming in a public library, as well as data related to the use of Portal 2 in a New York City middle school classroom, reveal how the students created, showcased, analyzed, and experimented with online and offline artifacts and…

  11. Simulation of Layered Magma Chambers.

    ERIC Educational Resources Information Center

    Cawthorn, Richard Grant

    1991-01-01

    The principles of magma addition and liquid layering in magma chambers can be demonstrated by dissolving colored crystals. The concepts of density stratification and apparent lack of mixing of miscible liquids is convincingly illustrated with hydrous solutions at room temperature. The behavior of interstitial liquids in "cumulus" piles can be…

  12. Physics of magnetospheric boundary layers

    NASA Technical Reports Server (NTRS)

    Cairns, I. H.

    1993-01-01

    The central ideas of this grant are that the magnetospheric boundary layers link disparate regions of the magnetosphere together, and the global behavior of the magnetosphere can be understood only by understanding the linking mechanisms. Accordingly the present grant includes simultaneous research on the global, meso-, and micro-scale physics of the magnetosphere and its boundary layers. These boundary layers include the bow shock, magnetosheath, the plasma sheet boundary layer, and the ionosphere. Analytic, numerical and simulation projects have been performed on these subjects, as well as comparison of theoretical results with observational data. Very good progress has been made, with four papers published or in press and two additional papers submitted for publication during the six month period 1 June - 30 November 1993. At least two projects are currently being written up. In addition, members of the group have given papers at scientific meetings. The further structure of this report is as follows: section two contains brief accounts of research completed during the last six months, while section three describes the research projects intended for the grant's final period.

  13. High Performance Thin Layer Chromatography.

    ERIC Educational Resources Information Center

    Costanzo, Samuel J.

    1984-01-01

    Clarifies where in the scheme of modern chromatography high performance thin layer chromatography (TLC) fits and why in some situations it is a viable alternative to gas and high performance liquid chromatography. New TLC plates, sample applications, plate development, and instrumental techniques are considered. (JN)

  14. Interfacial Bioorthogonal Cross-Linking

    PubMed Central

    2015-01-01

    Described herein is interfacial bioorthogonal cross-linking, the use of bioorthogonal chemistry to create and pattern biomaterials through diffusion-controlled gelation at the liquid-gel interface. The basis is a rapid (k2 284000 M–1 s–1) reaction between strained trans-cyclooctene (TCO) and tetrazine (Tz) derivatives. Syringe delivery of Tz-functionalized hyaluronic acid (HA-Tz) to a bath of bis-TCO cross-linker instantly creates microspheres with a cross-linked shell through which bis-TCO diffuses freely to introduce further cross-linking at the interface. Tags can be introduced with 3D resolution without external triggers or templates. Water-filled hydrogel channels were prepared by simply reversing the order of addition. Prostate cancer cells encapsulated in the microspheres have 99% viability, proliferate readily, and form aggregated clusters. This process is projected to be useful in the fabrication of cell-instructive matrices for in vitro tissue models. PMID:25177528

  15. Cross-Cultural Counseling Concerns.

    ERIC Educational Resources Information Center

    Ahia, Chikezie Emmanuel

    1984-01-01

    Examines problems and concerns of cross cultural counseling and psychotherapy. Raises specific questions concerning research designs and approaches, differences in cosmology, epistemology, differences in nosology, and problems of evaluation or testing. (JAC)

  16. Single-Layer, Multicolor Electroluminescent Phosphors

    NASA Technical Reports Server (NTRS)

    Robertson, James B.

    1988-01-01

    Etching eliminated in producing phosphor layers for displays. New process enables production of single-layer, two-color phosphor layer without etching. Method of construction, beginning with glass substrate with electrode and insulator layers, involves deposition of green phosphor masking with metal mask or photoresist; diffusion or ion implantation of manganese through mask to produce red phosphor and removal of mask.

  17. Doped LZO buffer layers for laminated conductors

    DOEpatents

    Paranthaman, Mariappan Parans [Knoxville, TN; Schoop, Urs [Westborough, MA; Goyal, Amit [Knoxville, TN; Thieme, Cornelis Leo Hans [Westborough, MA; Verebelyi, Darren T [Oxford, MA; Rupich, Martin W [Framingham, MA

    2010-03-23

    A laminated conductor includes a metallic substrate having a surface, a biaxially textured buffer layer supported by the surface of the substrate, the biaxially textured buffer layer comprising LZO and a dopant for mitigating metal diffusion through the LZO, and a biaxially textured conductor layer supported by the biaxially textured buffer layer.

  18. Fluid Mechanics and Heat Transfer in Transitional Boundary Layers

    NASA Technical Reports Server (NTRS)

    Wang, Ting

    2007-01-01

    Experiments have been performed to investigate the effects of elevated free-stream turbulence and streamwise acceleration on flow and thermal structures in transitional boundary layers. The free-stream turbulence ranges from 0.5 to 6.4% and the streamwise acceleration ranges from K = 0 to 0.8 x 10(exp -6). The onset of transition, transition length and the turbulent spot formation rate are determined. The statistical results and conditionally sampled results of th streamwise and cross-stream velocity fluctuations, temperature fluctuations, Reynolds stress and Reynolds heat fluxes are presented.

  19. Hair receptor sensitivity to changes in laminar boundary layer shape.

    PubMed

    Dickinson, B T

    2010-03-01

    Biologists have shown that bat wings contain distributed arrays of flow-sensitive hair receptors. The hair receptors are hypothesized to feedback information on airflows over the bat wing for enhanced stability or maneuverability during flight. Here, we study the geometric specialization of hair-like structures for the detection of changes in boundary layer velocity profiles (shapes). A quasi-steady model that relates the flow velocity profile incident on the longitudinal axis of a hair to the resultant moment and shear force at the hair base is developed. The hair length relative to the boundary layer momentum thickness that maximizes the resultant moment and shear-force sensitivity to changes in boundary layer shape is determined. The sensitivity of the resultant moment and shear force is shown to be highly dependent on hair length. Hairs that linearly taper to a point are shown to provide greater output sensitivity than hairs of uniform cross-section. On an order of magnitude basis, the computed optimal hair lengths are in agreement with the range of hair receptor lengths measured on individual bat species. These results support the hypothesis that bats use hair receptors for detecting changes in boundary layer shape and provide geometric guidelines for artificial hair sensor design and application.

  20. Measurements of entropy-layer instabilities over cone-ogive-cylinders at Mach 6

    NASA Astrophysics Data System (ADS)

    Greenwood, Roger T.

    Predicting the onset of boundary layer transition is critical in hypersonic flight. To improve transition prediction methods, it is necessary to understand the underlying instability mechanisms that cause transition. Entropy-layer instabilities are of particular interest in the design of blunt reentry vehicles and other blunt supersonic and hypersonic vehicles. Entropy-layer instabilities from outside the boundary layer may enter the boundary layer and have a significant effect on transition. There is little experimental data for entropy-layer instabilities. Experimental measurements of what appear to be entropy-layer instabilities have been made in the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT) using surface pressure transducers and hot-wire anemometry. A long cone-ogive-cylinder model with interchangeable cone-ogive noses was used to generate the shock curvature that resulted in an entropy layer conducive to instability growth. The nosetip angles of the cone-ogive range from 25 to 40 degrees, with a majority of the measurements taken with the sharp 30 to 35-degree nosetips. Surface measurements of the entropy-layer instabilities using the 30 to 35-degree configurations show disturbances between 15 and 50 kHz. As the nosetip angle increases, the frequency of the instability decreases slightly. Results also show that the instability magnitude as measured on the model surface increases with downstream distance, then decreases, before starting to increase again. The decrease is likely due to stabilization that occurs during the entropy-layer swallowing process. Off-surface measurements using hot wires have also been made for each of the cone-ogive-cylinder configurations. These measurements show the location, frequency, and relative magnitude of the entropy-layer instability. As the instability progresses downstream, it grows inside the entropy layer, then at a certain distance downstream, the instability approaches the model surface and enters the boundary layer

  1. nBn and pBp infrared detectors with graded barrier layer, graded absorption layer, or chirped strained layer super lattice absorption layer

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath D. (Inventor); Ting, David Z. (Inventor); Hill, Cory J. (Inventor); Bandara, Sumith V. (Inventor)

    2010-01-01

    An nBn detector is described where for some embodiments the barrier layer has a concentration gradient, for some embodiments the absorption layer has a concentration gradient, and for some embodiments the absorption layer is a chirped strained layer super lattice. The use of a graded barrier or absorption layer, or the use of a chirped strained layer super lattice for the absorption layer, allows for design of the energy bands so that the valence band may be aligned across the device. Other embodiments are described and claimed.

  2. Organic photovoltaic cells utilizing ultrathin sensitizing layer

    DOEpatents

    Rand, Barry P.; Forrest, Stephen R.

    2011-05-24

    A photosensitive device includes a series of organic photoactive layers disposed between two electrodes. Each layer in the series is in direct contact with a next layer in the series. The series is arranged to form at least one donor-acceptor heterojunction, and includes a first organic photoactive layer comprising a first host material serving as a donor, a thin second organic photoactive layer comprising a second host material disposed between the first and a third organic photoactive layer, and the third organic photoactive layer comprising a third host material serving as an acceptor. The first, second, and third host materials are different. The thin second layer serves as an acceptor relative to the first layer or as a donor relative to the third layer.

  3. Electrochemical Characterization of Ultrathin Cross-Linked Metal Nanoparticle Films.

    PubMed

    Han, Chu; Percival, Stephen J; Zhang, Bo

    2016-09-01

    Here we report the preparation, characterization, and electrochemical study of conductive, ultrathin films of cross-linked metal nanoparticles (NPs). Nanoporous films ranging from 40 to 200 nm in thickness composed of gold and platinum NPs of ∼5 nm were fabricated via a powerful layer-by-layer spin coating process. This process allows preparation of uniform NP films as large as 2 × 2 cm(2) with precise control over thickness, structure, and electrochemical and electrocatalytic properties. Gold, platinum, and bimetallic NP films were fabricated and characterized using cyclic voltammetry, scanning electron microscopy, and conductance measurements. Their electrocatalytic activity toward the oxygen reduction reaction (ORR) was investigated. Our results show that the electrochemical activity of such NP films is initially hindered by the presence of dense thiolate cross-linking ligands. Both electrochemical cycling and oxygen plasma cleaning are effective means in restoring their electrochemical activity. Gold NP films have higher electric conductivity than platinum possibly due to more uniform film structure and closer particle-particle distance. The electrochemical and electrocatalytic performance of platinum NP films can be greatly enhanced by the incorporation of gold NPs. This work focuses on electrochemical characterization of cross-linked NP films and demonstrates several unique properties. These include quick and easy preparation, ultrathin and uniform film thickness, tunable structure and composition, and transferability to many other substrates.

  4. Rapid Prototyping Of Layered Composite Parts

    NASA Technical Reports Server (NTRS)

    Wolff, Edwin D.

    1992-01-01

    Numerically controlled cutting accelerates fabrication of layers. Proposed method derived from stereoscopic lithography. CATIA or CAEDS computer program used to generate three-dimensional mathematical model of prototype part. In model, geometry of part specified in layers, as in stereoscopic lithography. Model data for each layer fed to computer-numerically-controlled ultrasonic cutting machine. Sheet of prepreg (uncured composite material) of specified layer thickness placed in machine and cut, under control of model data, to specified shape of layer.

  5. Chemical solution seed layer for rabits tapes

    SciTech Connect

    Goyal, Amit; Paranthaman, Mariappan; Wee, Sung-Hun

    2014-06-10

    A method for making a superconducting article includes the steps of providing a biaxially textured substrate. A seed layer is then deposited. The seed layer includes a double perovskite of the formula A.sub.2B'B''O.sub.6, where A is rare earth or alkaline earth metal and B' and B'' are different rare earth or transition metal cations. A superconductor layer is grown epitaxially such that the superconductor layer is supported by the seed layer.

  6. Buffer layer for thin film structures

    DOEpatents

    Foltyn, Stephen R.; Jia, Quanxi; Arendt, Paul N.; Wang, Haiyan

    2010-06-15

    A composite structure including a base substrate and a layer of a mixture of strontium titanate and strontium ruthenate is provided. A superconducting article can include a composite structure including an outermost layer of magnesium oxide, a buffer layer of strontium titanate or a mixture of strontium titanate and strontium ruthenate and a top-layer of a superconducting material such as YBCO upon the buffer layer.

  7. Buffer layer for thin film structures

    DOEpatents

    Foltyn, Stephen R.; Jia, Quanxi; Arendt, Paul N.; Wang, Haiyan

    2006-10-31

    A composite structure including a base substrate and a layer of a mixture of strontium titanate and strontium ruthenate is provided. A superconducting article can include a composite structure including an outermost layer of magnesium oxide, a buffer layer of strontium titanate or a mixture of strontium titanate and strontium ruthenate and a top-layer of a superconducting material such as YBCO upon the buffer layer.

  8. Thermal conductivities of single- and multi-layer phosphorene: a molecular dynamics study.

    PubMed

    Zhang, Ying-Yan; Pei, Qing-Xiang; Jiang, Jin-Wu; Wei, Ning; Zhang, Yong-Wei

    2016-01-01

    As a new two-dimensional (2D) material, phosphorene has drawn growing attention owing to its novel electronic properties, such as layer-dependent direct bandgaps and high carrier mobility. Herein we investigate the in-plane and cross-plane thermal conductivities of single- and multi-layer phosphorene, focusing on geometrical (sample size, orientation and layer number) and strain (compression and tension) effects. A strong anisotropy is found in the in-plane thermal conductivity with its value along the zigzag direction being much higher than that along the armchair direction. Interestingly, the in-plane thermal conductivity of multi-layer phosphorene is insensitive to the layer number, which is in strong contrast to that of graphene where the interlayer interactions strongly influence the thermal transport. Surprisingly, tensile strain leads to an anomalous increase in the in-plane thermal conductivity of phosphorene, in particular in the armchair direction. Both the in-plane and cross-plane thermal conductivities can be modulated by external strain; however, the strain modulation along the cross-plane direction is more effective and thus more tunable than that along the in-plane direction. Our findings here are of great importance for the thermal management in phosphorene-based nanoelectronic devices and for thermoelectric applications of phosphorene.

  9. Fluidized bed layer-by-layer microcapsule formation.

    PubMed

    Richardson, Joseph J; Teng, Darwin; Björnmalm, Mattias; Gunawan, Sylvia T; Guo, Junling; Cui, Jiwei; Franks, George V; Caruso, Frank

    2014-08-26

    Polymer microcapsules can be used as bioreactors and artificial cells; however, preparation methods for cell-like microcapsules are typically time-consuming, low yielding, and/or involve custom microfluidics. Here, we introduce a rapid (∼30 min per batch, eight layers), scalable (up to 500 mg of templates), and efficient (98% yield) microcapsule preparation technique utilizing a fluidized bed for the layer-by-layer (LbL) assembly of polymers, and we investigate the parameters that govern the formation of robust capsules. Fluidization in water was possible for particles of comparable diameter to mammalian cells (>5 μm), with the experimental flow rates necessary for fluidization matching well with the theoretical values. Important variables for polymer film deposition and capsule formation were the concentration of polymer solution and the molecular weight of the polymer, while the volume of the polymer solution had a negligible impact. In combination, increasing the polymer molecular weight and polymer solution concentration resulted in improved film deposition and the formation of robust microcapsules. The resultant polymer microcapsules had a thickness of ∼5.5 nm per bilayer, which is in close agreement with conventionally prepared (quiescent (nonflow) adsorption/centrifugation/wash) LbL capsules. The technique reported herein provides a new way to rapidly generate microcapsules (approximately 8 times quicker than the conventional means), while being also amenable to scale-up and mass production. PMID:25113552

  10. Fluidized bed layer-by-layer microcapsule formation.

    PubMed

    Richardson, Joseph J; Teng, Darwin; Björnmalm, Mattias; Gunawan, Sylvia T; Guo, Junling; Cui, Jiwei; Franks, George V; Caruso, Frank

    2014-08-26

    Polymer microcapsules can be used as bioreactors and artificial cells; however, preparation methods for cell-like microcapsules are typically time-consuming, low yielding, and/or involve custom microfluidics. Here, we introduce a rapid (∼30 min per batch, eight layers), scalable (up to 500 mg of templates), and efficient (98% yield) microcapsule preparation technique utilizing a fluidized bed for the layer-by-layer (LbL) assembly of polymers, and we investigate the parameters that govern the formation of robust capsules. Fluidization in water was possible for particles of comparable diameter to mammalian cells (>5 μm), with the experimental flow rates necessary for fluidization matching well with the theoretical values. Important variables for polymer film deposition and capsule formation were the concentration of polymer solution and the molecular weight of the polymer, while the volume of the polymer solution had a negligible impact. In combination, increasing the polymer molecular weight and polymer solution concentration resulted in improved film deposition and the formation of robust microcapsules. The resultant polymer microcapsules had a thickness of ∼5.5 nm per bilayer, which is in close agreement with conventionally prepared (quiescent (nonflow) adsorption/centrifugation/wash) LbL capsules. The technique reported herein provides a new way to rapidly generate microcapsules (approximately 8 times quicker than the conventional means), while being also amenable to scale-up and mass production.

  11. Comb/serpentine/cross-bridge test structure for fabrication process evaluation

    NASA Technical Reports Server (NTRS)

    Sayah, Hoshyar R.; Buehler, Martin G.

    1988-01-01

    The comb/serpentine/cross-bridge structure was developed to monitor and evaluate same layer shorts and step coverage problems (open and high-resistance wire over steps) for integrated circuit fabrication processes. The cross-bridge provides local measurements of wire sheet resistance and wirewidth. These local parametric measurements are used in the analysis of the serpentine wire, which identifies step coverage problems. The comb/serpentine/cross-bridge structure was fabricated with 3 microns CMOS/bulk p-well process and tested using a computer-controlled parametric test system.

  12. X-Ray Studies of Layer Rigidity and C-Axis Expansion in Intercalated Layered Solids.

    NASA Astrophysics Data System (ADS)

    Lee, Soonil

    rigidity constant and the size dependence of the intercalants. Different staging behavior among different intercalated layered solids is discussed using Safran's phase diagram. We have constructed a novel Low Temperature X -Ray Diffraction (LTXRD) system which can be used to study the temperature dependent properties of solids (i.e. temperature dependent basal spacing variation). A closed cycle He -cryostat and 4-circle diffractometer have been modified. Instead of moving the whole cryostat to locate the sample at the center of the diffractometer as is usually done we employ a small goniometer inside of the cryostat for easy and accurate sample alignment and scanning. The combination of two small universal joints and square cross section sliding shafts makes it possible to control the inside goniometer from outside the cryostat. Use of a Kapton window allows us to visualize the inside sample and to reduce the X-ray absorption by the window.

  13. Cross flow filter for AEPSC: TIDD slipstream HGCU project preliminary design package for Westinghouse cross flow filter system

    SciTech Connect

    Haldipur, G.B.; Lippert, T.E.

    1989-06-16

    The Westinghouse ceramic cross-flow filter element is constructed of multiple layers of thin, porous ceramic plates that contain ribs to form gas flow channels. Consecutive layers of the ceramic plates are oriented such that the channels of alternating plates are at an angle of 90 degrees ( cross flow'') to each other. The current size of a ceramic cross flow filter element is 12 in. {times} 12 in. {times} 14 in. Both sides of the short channels (4 in.) are exposed to the particle-laden coal gas. One end of the long (12 in.) channels is sealed while the other end of the long channel is mounted to the clean gas plenum. The particle-laden coal gas flows through the roof and floor'' of the porous ceramic plates that comprise the short, dirty side'' channels. The gas flows through the porous plates to the long, clean side'' channels. The gas flows through the porous plates to the long, clean side'' channels and finally to the clean gas plenum. The dust cake on the dirty side'' channels is periodically removed by applying a high-pressure reverse pulse of dry, clean gas through the clean gas plenum. For the TIDD plant filter slipstream, air will be utilized for filter cleaning.

  14. Cross flow filter for AEPSC: TIDD slipstream HGCU project preliminary design package for Westinghouse cross flow filter system. Final submittal

    SciTech Connect

    Haldipur, G.B.; Lippert, T.E.

    1989-06-16

    The Westinghouse ceramic cross-flow filter element is constructed of multiple layers of thin, porous ceramic plates that contain ribs to form gas flow channels. Consecutive layers of the ceramic plates are oriented such that the channels of alternating plates are at an angle of 90 degrees (``cross flow``) to each other. The current size of a ceramic cross flow filter element is 12 in. {times} 12 in. {times} 14 in. Both sides of the short channels (4 in.) are exposed to the particle-laden coal gas. One end of the long (12 in.) channels is sealed while the other end of the long channel is mounted to the clean gas plenum. The particle-laden coal gas flows through the ``roof and floor`` of the porous ceramic plates that comprise the short, ``dirty side`` channels. The gas flows through the porous plates to the long, ``clean side`` channels. The gas flows through the porous plates to the long, ``clean side`` channels and finally to the clean gas plenum. The dust cake on the ``dirty side`` channels is periodically removed by applying a high-pressure reverse pulse of dry, clean gas through the clean gas plenum. For the TIDD plant filter slipstream, air will be utilized for filter cleaning.

  15. Dynamical Model Simulation of the Morning Boundary Layer Development in Deep Mountain Valleys.

    NASA Astrophysics Data System (ADS)

    Bader, David C.; McKee, Thomas B.

    1983-03-01

    A dry, two-dimensional version of the Colorado State University Multi-dimensional Cloud/Mesoscale Model was used to study the cross-valley evolution of the wind and temperature structures in an idealized east-west oriented mountain valley. Two simulations were performed, one in which the valley was heated symmetrically and a second in which a mid-latitude heating distribution was imposed. Both runs were initiated identically with a stable layer filling the valley to ridgetop and a neutral layer above the ridge. A specified sinusoidal surface potential temperature flux function approximating the diurnal cycle forced the model at the lower boundary.The results of the two simulations were remarkably similar. The model realistically reproduced the gross features found in actual valleys in both structure and timing. The simulated inversions were destroyed three and one-half hours after sunrise as a result of a neutral layer growing up from the surface meeting a descending inversion top. Slope winds with speeds of 3-5 m s1 developed over both sidewalls two and one-half hours after sunrise. Both cases revealed the development of strongly stable pockets of air over the sidewalls which form when cold air advected upslope loses its buoyancy at higher elevations. These stable pockets temporarily block the slope flow and force transient cross-valley circulations to form which act to destabilize the valley boundary layer. Cross-valley mixing and gravity waves rapidly redistribute heat across the valley to prevent large potential temperature gradients from forming. As a result, oven large differences in heating rates between opposing sidewalls do not result in significant cross-valley potential temperature differences. Organized cross-valley circulations and eddy motions enhance lateral mixing in the stable layer as well.

  16. Deep layer malt drying modelling

    SciTech Connect

    Lopez, A.; Virseda, P.; Martinez, G.; Llorca, M.

    1997-05-01

    In malt production drying operation plays an important role in the total processing cost, however there are not many studies on malt drying modeling and optimization. In this paper a deep layer malt drying mathematical model in the form of four partial differential equations is presented. To determine drying constants, malt thin layer drying experiments at several air temperatures and relative humidities were made. The model were validated at industrial scale. The greatest energy savings, approximately 5.5% in fuel and 7.5% in electric energy, were obtained by an additional (and increased) air recirculation, which is carried out during the last 6 hours of the drying process and a significant decrease of air flow-rate during the last 6 hours of the drying process.

  17. Fluctuation phenomena in layered superconductors

    SciTech Connect

    Klemm, R.A.

    1996-10-01

    Gaussian fluctuations in layered superconductors have been the subject of study for many years. Although the FD was studied in detail long ago, the FC (fluctuation conductivity) was studied only recently, since the MT and DOS diagrams were previously neglected. Recent comparisons with experiment on YBCO have shown that the DOS diagrams are important and can lead to qualitatively different behaviors for the FC parallel and perpendicular to the layers. In both cases, Gaussian fluctuations fit the data above {Tc} very well, even for YBCO. To date, nearly all calculations of fluctuation quantities were for B{parallel}{cflx c}. Nevertheless, it should be possible to treat an arbitrary B, but the evaluation of the required matrix elements for the fluctuation quantities will be more complicated.

  18. Angled Layers in Super Resolution

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Researchers used a special imaging technique with the panoramic camera on NASA's Mars Exploration Rover Opportunity to get as detailed a look as possible at a target region near eastern foot of 'Burns Cliff.' The intervening terrain was too difficult for driving the rover closer. The target is the boundary between two sections of layered rock. The layers in lower section (left) run at a marked angle to the layers in next higher section (right).

    This view is the product of a technique called super resolution. It was generated from data acquired on sol 288 of Opportunity's mission (Nov. 14, 2004) from a position along the southeast wall of 'Endurance Crater.' Resolution slightly higher than normal for the panoramic camera was synthesized for this view by combining 17 separate images of this scene, each one 'dithered' or pointed slightly differently from the previous one. Computer manipulation of the individual images was then used to generate a new synthetic view of the scene in a process known mathematically as iterative deconvolution, but referred to informally as super resolution. Similar methods have been used to enhance the resolution of images from the Mars Pathfinder mission and the Hubble Space Telescope.

  19. CFCS and the ozone layer.

    PubMed

    Hayman, G D

    1997-05-01

    Ozone is an important constituent of the atmosphere. Ozone forms a distinct layer in the lower stratosphere known as the ozone layer. The ozone layer acts as a fragile shield because it protects man and other life forms from exposure to harmful short-wavelength ultraviolet (UV) radiation. The agents, particularly chemical, which affect the amount of ozone present in the atmosphere have been a source of concern for more than 20 years. This has been reinforced by the dramatic decline of stratospheric ozone levels first measured in Antarctica and now apparent worldwide. The combination of routine measurements of ozone depletion, careful laboratory studies and mathematical modelling of ozone in the atmosphere, has demonstrated that the reactive fragments produced when chlorofluorocarbons (CFCs), halons and other halogenated compounds break down in the stratosphere are responsible for the ozone loss. As CFCs have widespread and sometimes apparently essential uses in modern society, there has been an intense effort to develop safe, effective replacements which have a negligible or much smaller impact on the environment. The Montreal Protocol, signed by over 140 nations, has been implemented to control and phase out the chemical compounds responsible for ozone loss.

  20. Mixed Layers and Satellite Retrievals

    NASA Technical Reports Server (NTRS)

    Boers, R.

    1984-01-01

    As part of the process to determine whether it is possible to retrieve boundary layer structure with the current sounding techniques, temperature retievals were performed for radiosonde profiles that showed temperature inversions. It was found that when temperature inversions exceed 8 to 10 C a retrieval will indeed show a temperature increase with height over a limited vertical distance. For weaker inversions retrieved temperatures are generally smoothly decreasing with height. It is, however, impossible to determine the actual mixed layer height from the retrievals. Whether the water vapor channels could be used in observing mixed layer structure was investigated. Temperature inversions are accompanied by significant drops in relative humidity. While this effect is very pronounced in parts of the trade wind regimes with relative humidity drops of up to 60%, it is widespread in other areas of the ocean as well. A simulation experiment was performed in which brightness temperatures were computed for smooth temperature and humidity profiles and compared with those computed from inversion profiles.

  1. Optimized capping layers for EUV multilayers

    DOEpatents

    Bajt, Sasa; Folta, James A.; Spiller, Eberhard A.

    2004-08-24

    A new capping multilayer structure for EUV-reflective Mo/Si multilayers consists of two layers: A top layer that protects the multilayer structure from the environment and a bottom layer that acts as a diffusion barrier between the top layer and the structure beneath. One embodiment combines a first layer of Ru with a second layer of B.sub.4 C. Another embodiment combines a first layer of Ru with a second layer of Mo. These embodiments have the additional advantage that the reflectivity is also enhanced. Ru has the best oxidation resistance of all materials investigated so far. B.sub.4 C is an excellent barrier against silicide formation while the silicide layer formed at the Si boundary is well controlled.

  2. Cross-Layer Service Discovery Mechanism for OLSRv2 Mobile Ad Hoc Networks

    PubMed Central

    Vara, M. Isabel; Campo, Celeste

    2015-01-01

    Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering and advertising services integrated into the Optimized Link State Routing Protocol Version 2 (OLSRv2). In previous studies, we demonstrated the validity of a similar service discovery mechanism integrated into the previous version of OLSR (OLSRv1). In order to advertise services, we have added a new type-length-value structure (TLV) to the OLSRv2 protocol, called service discovery message (SDM), according to the Generalized MANET Packet/Message Format defined in Request For Comments (RFC) 5444. Each node in the ad hoc network only advertises its own services. The advertisement frequency is a user-configurable parameter, so that it can be modified depending on the user requirements. Each node maintains two service tables, one to store information about its own services and another one to store information about the services it discovers in the network. We present simulation results, that compare our service discovery integrated into OLSRv2 with the one defined for OLSRv1 and with the integration of service discovery in Ad hoc On-demand Distance Vector (AODV) protocol, in terms of service discovery ratio, service latency and network overhead. PMID:26205272

  3. Cross-Layer Service Discovery Mechanism for OLSRv2 Mobile Ad Hoc Networks.

    PubMed

    Vara, M Isabel; Campo, Celeste

    2015-01-01

    Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering and advertising services integrated into the Optimized Link State Routing Protocol Version 2 (OLSRv2). In previous studies, we demonstrated the validity of a similar service discovery mechanism integrated into the previous version of OLSR (OLSRv1). In order to advertise services, we have added a new type-length-value structure (TLV) to the OLSRv2 protocol, called service discovery message (SDM), according to the Generalized MANET Packet/Message Format defined in Request For Comments (RFC) 5444. Each node in the ad hoc network only advertises its own services. The advertisement frequency is a user-configurable parameter, so that it can be modified depending on the user requirements. Each node maintains two service tables, one to store information about its own services and another one to store information about the services it discovers in the network. We present simulation results, that compare our service discovery integrated into OLSRv2 with the one defined for OLSRv1 and with the integration of service discovery in Ad hoc On-demand Distance Vector (AODV) protocol, in terms of service discovery ratio, service latency and network overhead. PMID:26205272

  4. Cross layer optimization for cloud-based radio over optical fiber networks

    NASA Astrophysics Data System (ADS)

    Shao, Sujie; Guo, Shaoyong; Qiu, Xuesong; Yang, Hui; Meng, Luoming

    2016-07-01

    To adapt the 5G communication, the cloud radio access network is a paradigm introduced by operators which aggregates all base stations computational resources into a cloud BBU pool. The interaction between RRH and BBU or resource schedule among BBUs in cloud have become more frequent and complex with the development of system scale and user requirement. It can promote the networking demand among RRHs and BBUs, and force to form elastic optical fiber switching and networking. In such network, multiple stratum resources of radio, optical and BBU processing unit have interweaved with each other. In this paper, we propose a novel multiple stratum optimization (MSO) architecture for cloud-based radio over optical fiber networks (C-RoFN) with software defined networking. Additionally, a global evaluation strategy (GES) is introduced in the proposed architecture. MSO can enhance the responsiveness to end-to-end user demands and globally optimize radio frequency, optical spectrum and BBU processing resources effectively to maximize radio coverage. The feasibility and efficiency of the proposed architecture with GES strategy are experimentally verified on OpenFlow-enabled testbed in terms of resource occupation and path provisioning latency.

  5. Cross-Layer Service Discovery Mechanism for OLSRv2 Mobile Ad Hoc Networks.

    PubMed

    Vara, M Isabel; Campo, Celeste

    2015-07-20

    Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering and advertising services integrated into the Optimized Link State Routing Protocol Version 2 (OLSRv2). In previous studies, we demonstrated the validity of a similar service discovery mechanism integrated into the previous version of OLSR (OLSRv1). In order to advertise services, we have added a new type-length-value structure (TLV) to the OLSRv2 protocol, called service discovery message (SDM), according to the Generalized MANET Packet/Message Format defined in Request For Comments (RFC) 5444. Each node in the ad hoc network only advertises its own services. The advertisement frequency is a user-configurable parameter, so that it can be modified depending on the user requirements. Each node maintains two service tables, one to store information about its own services and another one to store information about the services it discovers in the network. We present simulation results, that compare our service discovery integrated into OLSRv2 with the one defined for OLSRv1 and with the integration of service discovery in Ad hoc On-demand Distance Vector (AODV) protocol, in terms of service discovery ratio, service latency and network overhead.

  6. Reconnection layer bounded by switch-off shocks: Dayside magnetopause crossing by THEMIS D

    NASA Astrophysics Data System (ADS)

    Sonnerup, Bengt; Paschmann, Götz; Haaland, Stein; Phan, Tai; Eriksson, Stefan

    2016-04-01

    We discuss observations of reconnection, obtained by Time History of Events and Macroscale Interactions during Substorms (THEMIS) D during an outward bound traversal of the low-latitude dayside magnetopause. The reconnection signatures include high magnetic shear, a southward directed Alfvénic jet, bounded by slow-mode shocks near the switch-off limit (as in the symmetric Petschek geometry), a small, sunward directed normal magnetic field and plasma inflow into the jet from both sides. We conclude that cold, unmeasured ionospheric ions helped establish the symmetry. The effective ion mass, estimated from the switch-off condition, was 2.39 amu on the magnetospheric side, where the number density was inferred from the spacecraft potential, and 1.09 amu on the magnetosheath side. After a modest pressure correction in the magnetospheric shock, the MHD jump conditions for density, pressure, temperature, and entropy were well satisfied. The shock jumps were much larger on the magnetosphere side than on the magnetosheath side; we show this to be a plasma β effect. The main dissipation mechanism appears to be irreversible transfer between thermal motion parallel and perpendicular to the field, such that both shocks bring about approximate downstream temperature isotropy. Hall currents and electric fields were present, albeit in a strongly asymmetric configuration. The magnetospheric shock had longer duration than the magnetosheath one, possibly as a result of a nonconstant magnetopause speed. We infer an average earthward magnetopause speed (14 km/s), corresponding nominal shock thicknesses (12 and 6 λi), dimensionless reconnection rates (0.061-0.085), and reconnection wedge angles (5° between shocks; 13° between separatrices).

  7. Neutrally Stratified Turbulent Ekman Boundary Layer: Universal Similarity for a Transitional Rough Surface

    NASA Astrophysics Data System (ADS)

    Afzal, Noor

    2009-08-01

    The geostrophic Ekman boundary layer for large Rossby number ( Ro) has been investigated by exploring the role played by the mesolayer (intermediate layer) lying between the traditional inner and outer layers. It is shown that the velocity and Reynolds shear stress components in the inner layer (including the overlap region) are universal relations, explicitly independent of surface roughness. This universality of predictions has been supported by observations from experiment, field and direct numerical simulation (DNS) data for fully smooth, transitionally rough and fully rough surfaces. The maxima of Reynolds shear stresses have been shown to be located in the mesolayer of the Ekman boundary layer, whose scale corresponds to the inverse square root of the friction Rossby number. The composite wall-wake universal relations for geostrophic velocity profiles have been proposed, and the two wake functions of the outer layer have been estimated by an eddy viscosity closure model. The geostrophic drag and cross-isobaric angle predictions yield universal relations, which are also supported by extensive field, laboratory and DNS data. The proposed predictions for the geostrophic drag and the cross-isobaric angle compare well with data for Rossby number Ro ≥ 105. The data show low Rossby number effects for Ro < 105 and higher-order effects due to the mesolayer compare well with the data for Ro ≥ 103.

  8. Effect of interfacial layer on water flow in nanochannels: Lattice Boltzmann simulations

    NASA Astrophysics Data System (ADS)

    Jin, Yakang; Liu, Xuefeng; Liu, Zilong; Lu, Shuangfang; Xue, Qingzhong

    2016-04-01

    A novel interfacial model was proposed to understand water flow mechanism in nanochannels. Based on our pore-throat nanochannel model, the effect of interfacial layer on water flow in nanochannels was quantitatively studied using Lattice Boltzmann method (LBM). It is found that both the permeability of nanochannel and water velocity in the nanochannel dramatically decrease with increasing the thickness of interfacial layer. The permeability of nanochannel with pore radius of 10 nm decreases by about three orders of magnitude when the thickness of interfacial layer is changed from 0 nm to 3 nm gradually. Furthermore, it has been demonstrated that the cross-section shape has a great effect on the water flow inside nanochannel and the effect of interfacial layer on the permeability of nanochannel has a close relationship with cross-section shape when the pore size is smaller than 12 nm. Besides, both pore-throat ratio and throat length can greatly affect water flow in nanochannels, and the influence of interfacial layer on water flow in nanochannels becomes more evident with increasing pore-throat ratio and throat length. Our theoretical results provide a simple and effective method to study the flow phenomena in nano-porous media, particularly to quantitatively study the interfacial layer effect in nano-porous media.

  9. Boundary layer receptivity and control

    NASA Technical Reports Server (NTRS)

    Hill, D. C.

    1993-01-01

    Receptivity processes initiate natural instabilities in a boundary layer. The instabilities grow and eventually break down to turbulence. Consequently, receptivity questions are a critical element of the analysis of the transition process. Success in modeling the physics of receptivity processes thus has a direct bearing on technological issues of drag reduction. The means by which transitional flows can be controlled is also a major concern: questions of control are tied inevitably to those of receptivity. Adjoint systems provide a highly effective mathematical method for approaching many of the questions associated with both receptivity and control. The long term objective is to develop adjoint methods to handle increasingly complex receptivity questions, and to find systematic procedures for deducing effective control strategies. The most elementary receptivity problem is that in which a parallel boundary layer is forced by time-harmonic sources of various types. The characteristics of the response to such forcing form the building blocks for more complex receptivity mechanisms. The first objective of this year's research effort was to investigate how a parallel Blasius boundary layer responds to general direct forcing. Acoustic disturbances in the freestream can be scattered by flow non-uniformities to produce Tollmien-Schlichting waves. For example, scattering by surface roughness is known to provide an efficient receptivity path. The present effort is directed towards finding a solution by a simple adjoint analysis, because adjoint methods can be extended to more complex problems. In practice, flows are non-parallel and often three-dimensional. Compressibility may also be significant in some cases. Recent developments in the use of Parabolized Stability Equations (PSE) offer a promising possibility. By formulating and solving a set of adjoint parabolized equations, a method for mapping the efficiency with which external forcing excites the three

  10. Stabilization of soybean oil bodies by enzyme (laccase) cross-linking of adsorbed beet pectin coatings.

    PubMed

    Chen, Bingcan; McClements, David Julian; Gray, David A; Decker, Eric Andrew

    2010-08-25

    Soybean oil bodies are naturally coated by a layer of phospholipids and oleosin proteins, which protect them from in vivo environmental stresses. When oil bodies are incorporated into food products, they encounter new environmental stresses such as changes in pH, ionic strength, and temperature. Consequently, additional protection mechanisms are often needed to stabilize them. The purpose of this study was to determine whether soybean oil bodies could be stabilized by coating them with a layer of cross-linked anionic polysaccharide (beet pectin). The beet pectin layer was cross-linked via its ferulic acid groups using laccase (an enzyme that catalyzes the oxidation of phenolic groups). Oil body suspensions were prepared that contained 1 wt % oil and 0.06 wt % beet pectin at pH 7 and were then adjusted to pH 4.5 to promote electrostatic deposition of the beet pectin molecules onto the surfaces of the oil bodies. Laccase was then added to promote cross-linking of the adsorbed beet pectin layer. Cross-linked pectin-coated oil bodies had similar or better stability than uncoated oil bodies to pH changes (3 to 7), NaCl addition (0 to 500 mM), and freeze-thaw cycling (-20 °C for 22 h; +40 °C for 2 h). These pectin-coated oil bodies may provide a convenient means of incorporating soybean oil into food and other products.

  11. Accurate Cross Sections for Microanalysis

    PubMed Central

    Rez, Peter

    2002-01-01

    To calculate the intensity of x-ray emission in electron beam microanalysis requires a knowledge of the energy distribution of the electrons in the solid, the energy variation of the ionization cross section of the relevant subshell, the fraction of ionizations events producing x rays of interest and the absorption coefficient of the x rays on the path to the detector. The theoretical predictions and experimental data available for ionization cross sections are limited mainly to K shells of a few elements. Results of systematic plane wave Born approximation calculations with exchange for K, L, and M shell ionization cross sections over the range of electron energies used in microanalysis are presented. Comparisons are made with experimental measurement for selected K shells and it is shown that the plane wave theory is not appropriate for overvoltages less than 2.5 V. PMID:27446747

  12. Tomographic reconstruction of layered tissue structures

    NASA Astrophysics Data System (ADS)

    Hielscher, Andreas H.; Azeez-Jan, Mohideen; Bartel, Sebastian

    2001-11-01

    In recent years the interest in the determination of optical properties of layered tissue structure has resurfaced. Applications include, for example, studies on layered skin tissue and underlying muscles, imaging of the brain underneath layers of skin, skull, and meninges, and imaging of the fetal head in utero beneath the layered structures of the maternal abdomen. In this work we approach the problem of layered structures in the framework of model-based iterative image reconstruction schemes. These schemes are currently developed to determine the optical properties inside tissue from measurement on the surface. If applied to layered structure these techniques yield substantial improvements over currently available semi-analytical approaches.

  13. Subsurface plankton layers in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Churnside, James H.; Marchbanks, Richard D.

    2015-06-01

    The first synoptic measurements of subsurface plankton layers were made in the western Arctic Ocean in July 2014 using airborne lidar. Layers were detected in open water and in pack ice where up to 90% of the surface was covered by ice. Layers under the ice were less prevalent, weaker, and shallower than those in open water. Layers were more prevalent in the Chukchi Sea than in the Beaufort Sea. Three quarters of the layers observed were thinner than 5 m. The presence of these layers, which are not adequately captured in satellite data, will influence primary productivity, secondary productivity, fisheries recruitment, and carbon export to the benthos.

  14. A laboratory investigation of potential double layers

    NASA Technical Reports Server (NTRS)

    Leung, Philip

    1987-01-01

    In a triple plasma device, the injection of electron current from the source chamber to the target chamber causes the formation of a potential double layer. At a low current density, the space charge of the injected current produces a virtual cathode-type potential double layer. This double layer is stable, and various wave instabilities are observed to associate with this double layer. As the current density is increased, the double layer becomes unstable, and a moving double layer results. As the current density is increased further, the enhanced ionization causes the neutralization of the space charge of the electron beam, and the beam plasma discharge is ignited.

  15. A laboratory investigation of potential double layers

    NASA Technical Reports Server (NTRS)

    Leung, Philip

    1987-01-01

    In a triple plasma device, the injection of electron current from the source chamber to the target chamber causes the formation of a potential double layer. At a low current density, the space charge of the injected current produces a virtual cathode-type potential double layer. This double layer is stable and various wave instabilities are observed to associate with this double layer. As the current density is increased, the double layer becomes unstable and a moving double layer results. As the current density is increased further, the enhanced ionization causes the neutralization of the space charge of the electron beam and the 'beam plasma discharge' is ignited.

  16. What can cross-bedding tell us?

    NASA Astrophysics Data System (ADS)

    Douillet, G.; Kueppers, U.; Dingwell, D. B.

    2014-12-01

    Pyroclastic density currents (PDCs) are a common transport mechanism associated with explosive eruptions. They behave as particulate density current (flows of particles and fluid, whose driving force is the excess density compared to the ambient fluid). The particles thus are the defining part of the flow acting as the agent of momentum and the resultant deposits, making PDC sedimentology fundamental. We combine wind tunnel measurements with nontraditional field techniques to consider cross-bedding from dilute PDCs from the mm to the km scale. Each deposited particle requires 1) momentum to reach its final location, but 2) sufficiently low shearing to halt at this place. A range of shearing is constrained from wind tunnel measurements. The results are combined with field data from lacquer peel sampling (an outcrop is impregnated with a solidifying glue, preserving the primary organization of the grains). This enables quantification of the grain size of mm-scale laminae, giving an order of magnitude of turbulence during deposition. The lacquer peel technique also imaged cm-scale, soft sediment deformation patterns producing overturned beds. These are interpreted as related to Kelvin-Helmholtz shear instabilities between a granular-based flow and the bed. Dune bedform (DBs) cross-stratification at the m scale generally have an overall stoss-aggrading stacking pattern. Often interpreted as indicating supercritical flows, the wind-tunnel results and DBs' geometry rather suggest they are a specificity of particulate density currents with high deposition rates. Ground penetrating radar (GPR) reveals the 3D stability in location of a DB over several m depth, although stacking patterns vary with time and laterally. This emphasizes the primary influence of the basal boundary layer in the depositional dynamics. At the 100 m scale, DBs' shape evolves in dimensions and form, calling for 3D datasets. Terrestrial laser scanner and photogrammetry enable quantification of the

  17. Enhancement effect of short-circuit currents of Si solar cells with inclusion of indium tin oxide layers on metal-semiconductor interfaces

    NASA Astrophysics Data System (ADS)

    Ji, Hyung Yong; Parida, Bhaskar; Park, Seungil; Kim, Myeong Jun; Chung, Sang Jo; Kim, Keunjoo

    2015-10-01

    We investigated the enhancement effect on short-circuit currents by indium tin oxide contact layers imbedded in metal-semiconductor interfaces in Si solar cells. Both samples that incorporate the thin film layer and the crossed finger lines of indium tin oxide exhibit an enhancement of p-n junction photocurrents and depletion capacitances with enhanced bulk donor concentrations at the emitter contacts. The indium tin oxide layer provides the passivation layer on the Si emitter surface with reduced trap states and the carrier transport layer for charge collection. The Si solar cells with indium tin oxide showed improved performance in shunt resistance and short-circuit current.

  18. Computation of three-dimensional mixed convective boundary layer flow

    NASA Technical Reports Server (NTRS)

    Gadepalli, Prashandt; Rahman, Muhammad M.

    1995-01-01

    The paper presents the numerical solution of heat and mass transfer during cross-flow (orthogonal) mixed convection. In this class of flow, a buoyancy-driven transport in the vertical direction and a forced convective flow in the horizontal direction results in a three-dimensional boundary layer structure adjacent to the plate. The rates of heat and mass transfer are determined by a combined influence of the two transport processes. The equations for the conservation of mass, momentum, energy, and species concentration were solved along with appropriate boundary conditions to determine the distributions of velocity components, temperature, and concentration across the thickness of the boundary layer at different locations on the plate. Results were expressed in dimensionless form using Reynolds number, Richardson number for heat transfer, Richardson number for mass transfer, Prandtl number, and Schmidt number as parameters. It was found that the transport is dominated by buoyancy at smaller vertical locations and at larger distances away from the forced convection leading edge. Effects of forced convection appeared to be very strong at smaller horizontal distances from the leading edge. The cross stream forced convection enhanced the rate of heat and mass transfer by a very significant amount.

  19. Coleman v. American Red Cross.

    PubMed

    1990-04-01

    Cheryl Coleman became infected with the human immunodeficiency virus (HIV) after receiving a blood transfusion. Alleging that the blood she received was infected, she sued its supplier, the American Red Cross, to compel discovery of the donor's identity. Coleman asserted that without discovery of the donor's name, it would be impossible to determine whether the Red Cross adequately had screened blood donors (there was no test to identify HIV in blood at that time) and therefore to establish a claim of negligence and the necessary proximate cause. The District Court held that the potential danger to the nation's volunteer blood supply system outweighed Coleman's need to discover the donor's identity.

  20. Neutral sheet crossings by ISEE-3 in the distant magnetotail

    NASA Technical Reports Server (NTRS)

    Heikkila, W. J.; Slavin, J. A.; Smith, E. J.; Baker, D. N.; Zwickl, R. D.

    1986-01-01

    The magnetic field data from ISEE-3 in the distant magnetotail at crossings of the field reversal (or neutral sheet) region are analyzed to determine the instantaneous direction of the normal component B(z) at the crossing. Crossings in the middle of the aberrated magnetotail near the apogee A2 of the first deep-tail orbit of ISEE-3 in January-February, 1983 were selected. Data for an interval of one hour is discussed at length to illustrate some of the difficulties that can occur. One particular smooth crossing at 15:56 UT, February 4, 1983, shows that complicated microstructure can occur in times shorter than one minute; averaging over long times may eliminate essential information for this purpose. By inspecting the magnetic field data at the highest resolution, however, it is shown that the direction of the plasma sheet flows and the sense of B(z) across the neutral sheet do not always agree with the reconnection models. Rather, they indicate that the low latitude boundary layer may play a significant role in the dynamics of the magnetotail.

  1. Interlayer exchange coupling between layers with perpendicular and easy-plane magnetic anisotropies

    NASA Astrophysics Data System (ADS)

    Fallarino, Lorenzo; Sluka, Volker; Kardasz, Bartek; Pinarbasi, Mustafa; Berger, Andreas; Kent, Andrew D.

    2016-08-01

    Interlayer exchange coupling between layers with perpendicular and easy-plane magnetic anisotropies separated by a non-magnetic spacer is studied using ferromagnetic resonance. The samples consist of a Co/Ni multilayer with perpendicular magnetic anisotropy and a CoFeB layer with easy-plane anisotropy separated by a variable thickness Ru layer. At a fixed frequency, we show that there is an avoided crossing of layer ferromagnetic resonance modes providing direct evidence for interlayer coupling. The mode dispersions for different Ru thicknesses are fit to a Heisenberg-type model to determine the interlayer exchange coupling strength and layer properties. The resulting interlayer exchange coupling varies continuously from antiferromagnetic to ferromagnetic as a function of the Ru interlayer thickness. These results show that the magnetic layer single domain ground state consists of magnetizations that can be significantly canted with respect to the layer planes and the canting can be tuned by varying the Ru thickness and the layer magnetic characteristics, a capability of interest for applications in spin-transfer torque devices.

  2. Turbulent mixing and transport in a thermally stratified interfacial layer in decaying grid turbulence

    NASA Astrophysics Data System (ADS)

    Jayesh, Yoon, Kyunghwan; Warhaft, Z.

    1991-05-01

    A stably stratified mixing layer, sandwiched in between regions of neutral turbulence, was studied in decaying grid turbulence. The layer, which was shearless, was formed by heating the upper half of the flow by means of elements placed at the entrance to the plenum of a large, open circuit low speed wind tunnel 0.91×0.91 m2 in cross section and 9.14 m in length. The hot air above mixed with the cold below forming the stratified layer in between. As the flow evolved and the turbulence decayed, the buoyancy forces increased relative to the inertial forces (i.e., the Richardson number increased) causing the heat flux to collapse. This resulted in a thinning of the mixing layer with downstream distance (rather than growth which occurs for the passive case). Inside the layer the vertical velocity variance diminished and the vertical heat flux correlation coefficient was reduced to zero. Smoke wire photographs showed a wavylike damped region inside the layer, surrounded by the normal, more energetic turbulence outside. Second-order turbulence quantities scaled in the same way with the local Richardson number both along the layer and across it. The two stably stratified cases studied had centerline Froude numbers of 95 and 65 at 40 mesh lengths from the grid. The results are compared to a passive thermal mixing layer and are contrasted with recent experiments concerning a constant temperature gradient in grid turbulence.

  3. Turbulent mixing and transport in a thermally stratified interfacial layer in decaying grid turbulence

    SciTech Connect

    Jayesh; Yoon, K.; Warhaft, Z. )

    1991-05-01

    A stably stratified mixing layer, sandwiched in between regions of neutral turbulence, was studied in decaying grid turbulence. The layer, which was shearless, was formed by heating the upper half of the flow by means of elements placed at the entrance to the plenum of a large, open circuit low speed wind tunnel 0.91{times}0.91 m{sup 2} in cross section and 9.14 m in length. The hot air above mixed with the cold below forming the stratified layer in between. As the flow evolved and the turbulence decayed, the buoyancy forces increased relative to the inertial forces (i.e., the Richardson number increased) causing the heat flux to collapse. This resulted in a thinning of the mixing layer with downstream distance (rather than growth which occurs for the passive case). Inside the layer the vertical velocity variance diminished and the vertical heat flux correlation coefficient was reduced to zero. Smoke wire photographs showed a wavylike damped region inside the layer, surrounded by the normal, more energetic turbulence outside. Second-order turbulence quantities scaled in the same way with the local Richardson number both along the layer and across it. The two stably stratified cases studied had centerline Froude numbers of 95 and 65 at 40 mesh lengths from the grid. The results are compared to a passive thermal mixing layer and are contrasted with recent experiments concerning a constant temperature gradient in grid turbulence.

  4. Lithium implantation at low temperature in silicon for sharp buried amorphous layer formation and defect engineering

    SciTech Connect

    Oliviero, E.; David, M. L.; Beaufort, M. F.; Barbot, J. F.; Fichtner, P. F. P.

    2013-02-28

    The crystalline-to-amorphous transformation induced by lithium ion implantation at low temperature has been investigated. The resulting damage structure and its thermal evolution have been studied by a combination of Rutherford backscattering spectroscopy channelling (RBS/C) and cross sectional transmission electron microscopy (XTEM). Lithium low-fluence implantation at liquid nitrogen temperature is shown to produce a three layers structure: an amorphous layer surrounded by two highly damaged layers. A thermal treatment at 400 Degree-Sign C leads to the formation of a sharp amorphous/crystalline interfacial transition and defect annihilation of the front heavily damaged layer. After 600 Degree-Sign C annealing, complete recrystallization takes place and no extended defects are left. Anomalous recrystallization rate is observed with different motion velocities of the a/c interfaces and is ascribed to lithium acting as a surfactant. Moreover, the sharp buried amorphous layer is shown to be an efficient sink for interstitials impeding interstitial supersaturation and {l_brace}311{r_brace} defect formation in case of subsequent neon implantation. This study shows that lithium implantation at liquid nitrogen temperature can be suitable to form a sharp buried amorphous layer with a well-defined crystalline front layer, thus having potential applications for defects engineering in the improvement of post-implantation layers quality and for shallow junction formation.

  5. Layer by Layer, Nano-particle "Only" Surface Modification of Filtration Membranes

    NASA Astrophysics Data System (ADS)

    Escobar-Ferrand, Luis

    . Imaging of our TFC membranes after permeation tests confirmed that no significant mechanical damage resulted, indicating integrity and robustness of the LbL deposited surface layers in typical applications. The selectivity of these novel TFC membranes was also tested using standard "rejection" tests normally used to characterize NF and RO membranes for their capabilities in typical applications, such as water softening or desalination. We report the dextran standards molecular weight "cut-off" (MWCO) using mixed dextrans from 1.5 to 500 KDa in dead-end stir cells, and the percentage of rejection of standard bivalent and monovalent salt solutions using steady cross flow permeation experiments. The results confirm rejection of at least 60% of even the smallest dextrans, an estimated dextran MWCO of 20 KDa, and rejection of 10% and 20% for monovalent (NaCl) and bivalent (MgSO4) salts, respectively, for all the TFC membranes studied, while the unmodified membranes showed no rejection capability at all. The work supports that nanoparticle based LbL surface modification of MF/UF membranes can produce filtration quality media for important water purification applications, such as nanofiltration (NF) softening processes, natural organic matter (NOM) elimination and possibly reverse osmosis (RO) desalination.

  6. Cross Flow Effects on Glaze Ice Roughness Formation

    NASA Technical Reports Server (NTRS)

    Tsao, Jen-Ching

    2004-01-01

    The present study examines the impact of large-scale cross flow on the creation of ice roughness elements on the leading edge of a swept wing under glaze icing conditions. A three-dimensional triple-deck structure is developed to describe the local interaction of a 3 D air boundary layer with ice sheets and liquid films. A linear stability analysis is presented here. It is found that, as the sweep angle increases, the local icing instabilities enhance and the most linearly unstable modes are strictly three dimensional.

  7. Energy harvesting from vibration with cross-linked polypropylene piezoelectrets

    SciTech Connect

    Zhang, Xiaoqing; Wu, Liming; Sessler, Gerhard M.

    2015-07-15

    Piezoelectret films are prepared by modification of the microstructure of polypropylene foam sheets cross-linked by electronic irradiation (IXPP), followed by proper corona charging. Young’s modulus, relative permittivity, and electromechanical coupling coefficient of the fabricated films, determined by dielectric resonance spectra, are about 0.7 MPa, 1.6, and 0.08, respectively. Dynamic piezoelectric d{sub 33} coefficients up to 650 pC/N at 200 Hz are achieved. The figure of merit (FOM, d{sub 33} ⋅ g{sub 33}) for a more typical d{sub 33} value of 400 pC/N is about 11.2 GPa{sup −1}. Vibration-based energy harvesting with one-layer and two-layer stacks of these films is investigated at various frequencies and load resistances. At an optimum load resistance of 9 MΩ and a resonance frequency of 800 Hz, a maximum output power of 120 μW, referred to the acceleration g due to gravity, is obtained for an energy harvester consisting of a one-layer IXPP film with an area of 3.14 cm{sup 2} and a seismic mass of 33.7 g. The output power can be further improved by using two-layer stacks of IXPP films in electric series. IXPP energy harvesters could be used to energize low-power electronic devices, such as wireless sensors and LED lights.

  8. Energy harvesting from vibration with cross-linked polypropylene piezoelectrets

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoqing; Wu, Liming; Sessler, Gerhard M.

    2015-07-01

    Piezoelectret films are prepared by modification of the microstructure of polypropylene foam sheets cross-linked by electronic irradiation (IXPP), followed by proper corona charging. Young's modulus, relative permittivity, and electromechanical coupling coefficient of the fabricated films, determined by dielectric resonance spectra, are about 0.7 MPa, 1.6, and 0.08, respectively. Dynamic piezoelectric d33 coefficients up to 650 pC/N at 200 Hz are achieved. The figure of merit (FOM, d33 ṡ g33) for a more typical d33 value of 400 pC/N is about 11.2 GPa-1. Vibration-based energy harvesting with one-layer and two-layer stacks of these films is investigated at various frequencies and load resistances. At an optimum load resistance of 9 MΩ and a resonance frequency of 800 Hz, a maximum output power of 120 μW, referred to the acceleration g due to gravity, is obtained for an energy harvester consisting of a one-layer IXPP film with an area of 3.14 cm2 and a seismic mass of 33.7 g. The output power can be further improved by using two-layer stacks of IXPP films in electric series. IXPP energy harvesters could be used to energize low-power electronic devices, such as wireless sensors and LED lights.

  9. Sparse coding for layered neural networks

    NASA Astrophysics Data System (ADS)

    Katayama, Katsuki; Sakata, Yasuo; Horiguchi, Tsuyoshi

    2002-07-01

    We investigate storage capacity of two types of fully connected layered neural networks with sparse coding when binary patterns are embedded into the networks by a Hebbian learning rule. One of them is a layered network, in which a transfer function of even layers is different from that of odd layers. The other is a layered network with intra-layer connections, in which the transfer function of inter-layer is different from that of intra-layer, and inter-layered neurons and intra-layered neurons are updated alternately. We derive recursion relations for order parameters by means of the signal-to-noise ratio method, and then apply the self-control threshold method proposed by Dominguez and Bollé to both layered networks with monotonic transfer functions. We find that a critical value αC of storage capacity is about 0.11|a ln a| -1 ( a≪1) for both layered networks, where a is a neuronal activity. It turns out that the basin of attraction is larger for both layered networks when the self-control threshold method is applied.

  10. Layer-by-layer nanoencapsulation of camptothecin with improved activity.

    PubMed

    Parekh, Gaurav; Pattekari, Pravin; Joshi, Chaitanya; Shutava, Tatsiana; DeCoster, Mark; Levchenko, Tatyana; Torchilin, Vladimir; Lvov, Yuri

    2014-04-25

    160 nm nanocapsules containing up to 60% of camptothecin in the core and 7-8 polyelectrolyte bilayers in the shell were produced by washless layer-by-layer assembly of heparin and block-copolymer of poly-l-lysine and polyethylene glycol. The outer surface of the nanocapsules was additionally modified with polyethylene glycol of 5 kDa or 20 kDa molecular weight to attain protein resistant properties, colloidal stability in serum and prolonged release of the drug from the capsules. An advantage of the LbL coated capsules is the preservation of camptothecin lactone form with the shell assembly starting at acidic pH and improved chemical stability of encapsulated drug at neutral and basic pH, especially in the presence of albumin that makes such formulation more active than free camptothecin. LbL nanocapsules preserve the camptothecin lactone form at pH 7.4 resulting in triple activity of the drug toward CRL2303 glioblastoma cell. PMID:24508806

  11. Layer-by-layer assemblies for cancer treatment and diagnosis

    PubMed Central

    Liu, Xi Qiu; Picart, Catherine

    2016-01-01

    The layer-by-layer (LbL) technique was introduced in the early 90s by Profs Moehwald, Lvov and Decher. Since then, it has undergone a series of technological developments, making it possible to engineer various theranostic platforms such as films and capsules, with precise control at the nanometer and micrometer scales. This Research News article highlights recent progress in the applications of LbL assemblies in the field of cancer therapy, diagnosis and fundamental biology study. The potentials of LbL-based systems as drug carriers are discussed, especially with regard to the engineering of innovative stimuli-responsive systems, and their advantageous multifunctionality in the development of new therapeutic tools. Then, the diagnostic functions of LbL assemblies are illustrated for detection and capture of rare cancer cells. Finally, LbL mimicking extracellular environments demonstrate the emerging potential for the study of cancer cell behaviors in vitro. We conclude by highlighting the advantages of LbL systems, important challenges that need to be overcome, and future perspectives in clinical practice. PMID:26390356

  12. Layer-by-layer nanoencapsulation of camptothecin with improved activity

    PubMed Central

    Parekh, Gaurav; Pattekari, Pravin; Joshi, Chaitanya; Shutava, Tatsiana; DeCoster, Mark; Levchenko, Tatyana; Torchilin, Vladimir; Lvov, Yuri

    2014-01-01

    160 nm nanocapsules containing up to 60% of camptothecin in the core and 7–8 polyelectrolyte bilayers in the shell were produced by washless layer-by-layer assembly of heparin and block-copolymer of poly-L-lysine and polyethylene glycol. The outer surface of the nanocapsules was additionally modified with polyethylene glycol of 5 kDa or 20 kDa molecular weight to attain protein resistant properties, colloidal stability in serum and prolonged release of the drug from the capsules. An advantage of the LbL coated capsules is the preservation of camptothecin lactone form with the shell assembly starting at acidic pH and improved chemical stability of encapsulated drug at neutral and basic pH, especially in the presence of albumin that makes such formulation more active than free camptothecin. LbL nanocapsules preserve the camptothecin lactone form at pH 7.4 resulting in triple activity of the drug toward CRL2303 glioblastoma cell. PMID:24508806

  13. Inkjet Deposition of Layer-by-Layer Assembled Films

    SciTech Connect

    Andres, C. M.; Kotov, Nicholas A.

    2010-09-23

    Layer-by-layer assembly (LBL) can create advanced composites with exceptional properties unavailable by other means, but the laborious deposition process and multiple dipping cycles hamper their utilization in microtechnologies and electronics. Multiple rinse steps provide both structural control and thermodynamic stability to LBL multilayers, but they significantly limit their practical applications and contribute significantly to the processing time and waste. Here we demonstrate that by employing inkjet technology one can deliver the necessary quantities of LBL components required for film buildup without excess, eliminating the need for repetitive rinsing steps. This feature differentiates this approach from all other recognized LBL modalities. Using a model system of negatively charged gold nanoparticles and positively charged poly(diallyldimethylammonium) chloride, the material stability, nanoscale control over thickness, and particle coverage offered by the inkjet LBL technique are shown to be equal or better than the case of multilayers made with traditional dipping cycles. The opportunity for fast deposition of complex metallic patterns using a simple inkjet printer is also shown. The additive nature of LBL deposition based on the formation of insoluble nanoparticle-polyelectrolyte complexes of various compositions provides an excellent opportunity for versatile, multicomponent, and noncontact patterning for the simple production of stratified patterns that are much needed in advanced devices.

  14. Inkjet Deposition of Layer by Layer Assembled Films

    PubMed Central

    Andres, Christine M.; Kotov, Nicholas A.

    2010-01-01

    Layer-by-layer assembly (LBL) can create advanced composites with exceptional properties unavailable by other means, but the laborious deposition process and multiple dipping cycles hamper their utilization in microtechnologies and electronics. Multiple rinse steps provide both structural control and thermodynamic stability to LBL multilayers but they significantly limit their practical applications and contribute significantly to the processing time and waste. Here we demonstrate that by employing inkjet technology one can deliver the necessary quantities of LBL components required for film build-up without excess, eliminating the need for repetitive rinsing steps. This feature differentiates this approach from all other recognized LBL modalities. Using a model system of negatively charged gold nanoparticles and positively charged poly(diallyldimethylammonium) chloride, the material stability, nanoscale control over thickness and particle coverage offered by the inkjet LBL technique are shown to be equal or better than the multilayers made with traditional dipping cycles. The opportunity for fast deposition of complex metallic patterns using a simple inkjet printer was also shown. The additive nature of LBL deposition based on the formation of insoluble nanoparticle-polyelectrolyte complexes of various compositions provides an excellent opportunity for versatile, multi-component, and non-contact patterning for the simple production of stratified patterns that are much needed in advanced devices. PMID:20863114

  15. Layer-by-Layer Assemblies for Cancer Treatment and Diagnosis.

    PubMed

    Liu, Xi Qiu; Picart, Catherine

    2016-02-10

    The layer-by-layer (LbL) technique was introduced in the early 1990s. Since then, it has undergone a series of technological developments, making it possible to engineer various theranostic platforms, such as films and capsules, with precise control at the nanometer and micrometer scales. Recent progress in the applications of LbL assemblies in the field of cancer therapy, diagnosis, and fundamental biological study are highlighted here. The potential of LbL-based systems as drug carriers is discussed, especially with regard to the engineering of innovative stimuli-responsive systems, and their advantageous multifunctionality in the development of new therapeutic tools. Then, the diagnostic functions of LbL assemblies are illustrated for detection and capture of rare cancer cells. Finally, LbL-mimicking extracellular environments demonstrate the emerging potential for the study of cancer cell behavior in vitro. The advantages of LbL systems, important challenges that need to be overcome, and future perspectives in clinical practice are then highlighted.

  16. 30 CFR 56.9104 - Railroad crossings.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Railroad crossings. 56.9104 Section 56.9104... Dumping Traffic Safety § 56.9104 Railroad crossings. Designated railroad crossings shall be posted with warning signs or signals, or shall be guarded when trains are passing. These crossings shall also...

  17. 30 CFR 57.9104 - Railroad crossings.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Railroad crossings. 57.9104 Section 57.9104... Dumping Traffic Safety § 57.9104 Railroad crossings. Designated railroad crossings shall be posted with warning signs or signals, or shall be guarded when trains are passing. These crossings shall also...

  18. 30 CFR 57.9104 - Railroad crossings.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Railroad crossings. 57.9104 Section 57.9104... Dumping Traffic Safety § 57.9104 Railroad crossings. Designated railroad crossings shall be posted with warning signs or signals, or shall be guarded when trains are passing. These crossings shall also...

  19. 30 CFR 56.9104 - Railroad crossings.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Railroad crossings. 56.9104 Section 56.9104... Dumping Traffic Safety § 56.9104 Railroad crossings. Designated railroad crossings shall be posted with warning signs or signals, or shall be guarded when trains are passing. These crossings shall also...

  20. 30 CFR 57.9104 - Railroad crossings.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Railroad crossings. 57.9104 Section 57.9104... Dumping Traffic Safety § 57.9104 Railroad crossings. Designated railroad crossings shall be posted with warning signs or signals, or shall be guarded when trains are passing. These crossings shall also...

  1. 30 CFR 57.9104 - Railroad crossings.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Railroad crossings. 57.9104 Section 57.9104... Dumping Traffic Safety § 57.9104 Railroad crossings. Designated railroad crossings shall be posted with warning signs or signals, or shall be guarded when trains are passing. These crossings shall also...

  2. 30 CFR 56.9104 - Railroad crossings.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Railroad crossings. 56.9104 Section 56.9104... Dumping Traffic Safety § 56.9104 Railroad crossings. Designated railroad crossings shall be posted with warning signs or signals, or shall be guarded when trains are passing. These crossings shall also...

  3. 30 CFR 56.9104 - Railroad crossings.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Railroad crossings. 56.9104 Section 56.9104... Dumping Traffic Safety § 56.9104 Railroad crossings. Designated railroad crossings shall be posted with warning signs or signals, or shall be guarded when trains are passing. These crossings shall also...

  4. 39 CFR 259.2 - Red Cross.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Red Cross. 259.2 Section 259.2 Postal Service....2 Red Cross. (a) General. The Postal Service and the Red Cross cooperate to maintain communication... those caused by enemy action. (b) Role of Postal Service. The Postal Service and the Red Cross...

  5. The cross politics of Ecuador's penal state.

    PubMed

    Garces, Chris

    2010-01-01

    This essay examines inmate "crucifixion protests" in Ecuador's largest prison during 2003-04. It shows how the preventively incarcerated-of whom there are thousands-managed to effectively denounce their extralegal confinement by embodying the violence of the Christian crucifixion story. This form of protest, I argue, simultaneously clarified and obscured the multiple layers of sovereign power that pressed down on urban crime suspects, who found themselves persecuted and forsaken both outside and within the space of the prison. Police enacting zero-tolerance policies in urban neighborhoods are thus a key part of the penal state, as are the politically threatened family members of the indicted, the sensationalized local media, distrustful neighbors, prison guards, and incarcerated mafia. The essay shows how the politico-theological performance of self-crucifixion responded to these internested forms of sovereign violence, and were briefly effective. The inmates' cross intervention hence provides a window into the way sovereignty works in the Ecuadorean penal state, drawing out how incarceration trends and new urban security measures interlink, and produce an array of victims. PMID:20662147

  6. The cross politics of Ecuador's penal state.

    PubMed

    Garces, Chris

    2010-01-01

    This essay examines inmate "crucifixion protests" in Ecuador's largest prison during 2003-04. It shows how the preventively incarcerated-of whom there are thousands-managed to effectively denounce their extralegal confinement by embodying the violence of the Christian crucifixion story. This form of protest, I argue, simultaneously clarified and obscured the multiple layers of sovereign power that pressed down on urban crime suspects, who found themselves persecuted and forsaken both outside and within the space of the prison. Police enacting zero-tolerance policies in urban neighborhoods are thus a key part of the penal state, as are the politically threatened family members of the indicted, the sensationalized local media, distrustful neighbors, prison guards, and incarcerated mafia. The essay shows how the politico-theological performance of self-crucifixion responded to these internested forms of sovereign violence, and were briefly effective. The inmates' cross intervention hence provides a window into the way sovereignty works in the Ecuadorean penal state, drawing out how incarceration trends and new urban security measures interlink, and produce an array of victims.

  7. Intelligent optical networking with photonic cross connections

    NASA Astrophysics Data System (ADS)

    Ceuppens, L.; Jerphagnon, Olivier L.; Lang, Jonathan; Banerjee, Ayan; Blumenthal, Daniel J.

    2002-09-01

    Optical amplification and dense wavelength division multiplexing (DWDM) have fundamentally changed optical transport networks. Now that these technologies are widely adopted, the bottleneck has moved from the outside line plant to nodal central offices, where electrical switching equipment has not kept pace. While OEO technology was (and still is) necessary for grooming and traffic aggregation, the transport network has dramatically changed, requiring a dramatic rethinking of how networks need to be designed and operated. While todays transport networks carry remarkable amounts of bandwidth, their optical layer is fundamentally static and provides for only simple point-to-point transport. Efficiently managing the growing number of wavelengths can only be achieved through a new breed of networking element. Photonic switching systems (PSS) can efficiently execute these functions because they are bit rate, wavelength, and protocol transparent. With their all-optical switch cores and interfaces, PSS can switch optical signals at various levels of granularity wavelength, sub band, and composite DWDM fiber levels. Though cross-connect systems with electrical switch cores are available, they perform these functions at very high capital costs and operational inefficiencies. This paper examines enabling technologies for deployment of intelligent optical transport networks (OTN), and takes a practical perspective on survivability architecture migration and implementation issues.

  8. MeV ion beam interaction with polymer films containing cross-linking agents

    SciTech Connect

    Evelyn, A. L.

    1999-06-10

    Polymer films containing cross linking enhancers were irradiated with MeV alpha particles to determine the effects of MeV ion beam interaction on these materials. The contributed effects from the electronic and nuclear stopping powers were separated by irradiating stacked thin films of polyvinyl chloride (PVC), polystyrene (PS) and polyethersulfone (PES). This layered system allowed most of the effects of the electronic energy deposited to be experienced by the first layers and the last layers to receive most of the effects of the nuclear stopping power. RGA, Raman microprobe analysis, RBS and FTIR measured changes in the chemical structures of the irradiated films. The characterization resolved the effects of the stopping powers on the PVC, PS and PES and the results were compared with those from previously studied polymers that did not contain any cross linking agents.

  9. Cellular Responses Modulated by FGF-2 Adsorbed on Albumin/Heparin Layer-by-Layer Assemblies

    PubMed Central

    Kumorek, Marta; Kubies, Dana; Filová, Elena; Houska, Milan; Kasoju, Naresh; Mázl Chánová, Eliška; Matějka, Roman; Krýslová, Markéta; Bačáková, Lucie; Rypáček, František

    2015-01-01

    In a typical cell culture system, growth factors immobilized on the cell culture surfaces can serve as a reservoir of bio-signaling molecules, without the need to supplement them additionally into the culture medium. In this paper, we report on the fabrication of albumin/heparin (Alb/Hep) assemblies for controlled binding of basic fibroblast growth factor (FGF-2). The surfaces were constructed by layer-by-layer adsorption of polyelectrolytes albumin and heparin and were subsequently stabilized by covalent crosslinking with glutaraldehyde. An analysis of the surface morphology by atomic force microscopy showed that two Alb/Hep bilayers are required to cover the surface of substrate. The formation of the Alb/Hep assemblies was monitored by the surface plasmon resonance (SPR), the infrared multiinternal reflection spectroscopy (FTIR MIRS) and UV/VIS spectroscopy. The adsorption of FGF-2 on the cross-linked Alb/Hep was followed by SPR. The results revealed that FGF-2 binds to the Alb/Hep assembly in a dose and time-dependent manner up to the surface concentration of 120 ng/cm2. The bioactivity of the adsorbed FGF-2 was assessed in experiments in vitro, using calf pulmonary arterial endothelial cells (CPAE). CPAE cells could attach and proliferate on Alb/Hep surfaces. The adsorbed FGF-2 was bioactive and stimulated both the proliferation and the differentiation of CPAE cells. The improvement was more pronounced at a lower FGF-2 surface concentration (30 ng/cm2) than on surfaces with a higher concentration of FGF-2 (120 ng/cm2). PMID:25945799

  10. Geodynamics: Layer cake or plum pudding?

    NASA Astrophysics Data System (ADS)

    Tackley, Paul J.

    2008-03-01

    Whether convection in the Earth's mantle extends through its entire depth or if the mantle is layered has long been debated. Recent research suggests that spatially and temporally intermittent or partial layering is the most likely solution.

  11. Layered Yardangs in Henry Crater

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-389, 12 June 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows wind-sculpted remnants of layered sedimentary rock that once completely covered the northwestern floor of Henry Crater, an ancient impact basin located at 11.7oN, 336.4oW. These landforms, shaped somewhat like inverted boat hulls, are 'textbook examples' of a wind erosion form known as a yardang. The image covers an area 2.3 km (1.4 mi) wide; sunlight illuminates the scene from the left.

  12. Ground Layer Laser Seeing Meter

    NASA Astrophysics Data System (ADS)

    Cavazzani, S.; Rodeghiero, G.; Capraro, I.; Ortolani, S.; Barbieri, C.; Zitelli, V.

    2014-03-01

    The seeing calculation and its evolution during the night is a key point for the operation of telescopes and adaptive optics systems. Currently, there are various instruments able to measure the seeing, for example, the DIMM (differential image motion monitor) and the MASS (multi aperture scintillation sensor). This paper describes a new tool for the local ground layer seeing measurement. In particular, we want to derive the Fried parameter r0 through a laser beam horizontal propagation. This is a new method for the experimental study of low-altitude atmospheric turbulence. Finally, we sketch an experimental setup for the Asiago Ekar Observatory and its possible applications.

  13. Bursts in inclined layer convection

    NASA Astrophysics Data System (ADS)

    Busse, F. H.; Clever, R. M.

    2000-08-01

    A new instability of longitudinal rolls in an inclined fluid layer heated from below is analyzed in the case of the Prandtl number P=0.71. The instability assumes the form of subharmonic undulations and evolves into a spatially chaotic pattern when the angle of inclination is of the order of 20°. The chaotic state rapidly decays and longitudinal rolls recover until the next burst of chaotic convection occurs. The theoretical findings closely correspond to recent experimental observations by Daniels et al. [Phys. Rev. Lett. (to be published)].

  14. Creating Cross-disciplinary Courses

    PubMed Central

    Reynolds, Elaine R.

    2012-01-01

    Because of its focus on the biological underpinnings of action and behavior, neuroscience intersects with many fields of human endeavor. Some of these cross-disciplinary intersections have been long standing, while others, such as neurotheology or neuroeconomics, are more recently formed fields. Many undergraduate institutions have sought to include cross-disciplinary courses in their curriculum because this style of pedagogy is often seen as applicable to real world problems. However, it can be difficult for faculty with specialized training within their discipline to expand beyond their own fields to offer cross-disciplinary courses. I have been creating a series of multi- or cross-disciplinary courses and have found some strategies that have helped me successfully teach these classes. I will discuss general strategies and tools in developing these types of courses including: 1) creating mixed experience classrooms of students and contributing faculty 2) finding the right tools that will allow you to teach to a mixed population without prerequisites 3) examining the topic using multiple disciplinary perspectives 4) feeding off student experience and interest 5) assessing the impact of these courses on student outcomes and your neuroscience program. This last tool in particular is important in establishing the validity of this type of teaching for neuroscience students and the general student population. PMID:23494491

  15. Redressing Cross-Dressed Shakespeare

    ERIC Educational Resources Information Center

    Martin, Thomas L.; Pesta, Duke

    2003-01-01

    Gender critics obsess over the boy actors who played female roles on the Elizabethan stage. But, in their far-fetched interpretation of Shakespearean drama as a spectacle of cross dressing, these new historicists lose sight of a fundamental principle of theater. Thomas Martin and Duke Pesta argue that with their prurient chatter of "the…

  16. Observations of Planet Crossing Asteroids

    NASA Technical Reports Server (NTRS)

    Tholen, David J.

    1999-01-01

    This grant funds the investigation of the Solar System's planet crossing asteroid population, principally the near Earth and trans-Neptunian objects, but also the Centaurs. Investigations include colorimetry at both visible and near infrared wavelengths, light curve photometry, astrometry, and a pilot project to find near Earth objects with small aphelion distances, which requires observations at small solar elongations.

  17. Improved Zero-Crossing Detector

    NASA Technical Reports Server (NTRS)

    Dick, G. John; Kuhnle, Paul F.

    1992-01-01

    Improved zero-crossing-detector circuit designed for precisely measuring difference between frequencies of two frequency-standard signal sources. Contains low-bandwidth first-stage amplifier and three limiting amplifiers, each "squares" signal bit more. Crosstalk eliminated and jitter reduced to about 10 to the negative 7th power microseconds.

  18. Crossing Thresholds in Academic Reading

    ERIC Educational Resources Information Center

    Abbott, Rob

    2013-01-01

    This paper looks at the conceptual thresholds in relation to academic reading which might be crossed by undergraduate English Literature students. It is part of a wider study following 16 students through three years of undergraduate study. It uses theoretical ideas from Bakhtin and Foucault to analyse interviews with English lecturers. It…

  19. Assessing Cross-Media Impacts

    ERIC Educational Resources Information Center

    Reiquam, Howard; And Others

    1975-01-01

    Using 1000 MW coal-fired central power stations as an example, the impacts upon other media (land, air, water) are analyzed when controls are imposed on one medium. The development of a methodology for assessing the cross-media impact of specific control technologies or strategies is illustrated. (Author/BT)

  20. Teaching Cross-Country Skiing.

    ERIC Educational Resources Information Center

    Nelson, Jonathan E.

    1984-01-01

    Cross-country skiing instruction can be done both inside and outside the gymnasium. This article provides activities to be performed inside to prepare students for skiing. Outside organization techniques and drills are suggested. A list of common errors is given. (DF)