WorldWideScience

Sample records for abb x2000 tilt

  1. ABB Oy Marinen varaosien hinnoittelu

    OpenAIRE

    Rämö, Jukka

    2014-01-01

    Tässä insinöörityössä käsiteltiin varaosien hinnoittelua. Opinnäytetyö koostuu kaikille avoimesta teoreettisesta viitekehyksestä sekä salaisesta osuudesta, joka sisältää yrityksen nykytilakartoituksen, hinnoitteluesimerkit ja kehitysehdotuksen. Insinöörityön tilaajana toimi ABB Oy Marine. Opinnäytetyön teoriaosuus jakaantuu kahteen osaan, ensimmäisessä osassa käydään läpi varaosa ja toisessa osassa sen hinnoittelu. Varaosaosiossa pohditaan varaosan merkitystä osana jälkimarkkinoita ja sen...

  2. Transient analysis capabilities at ABB-CE

    International Nuclear Information System (INIS)

    Kling, C.L.

    1992-01-01

    The transient capabilities at ABB-Combustion Engineering (ABB-CE) Nuclear Power are a function of the computer hardware and related network used, the computer software that has evolved over the years, and the commercial technical exchange agreements with other related organizations and customers. ABB-CEA is changing from a mainframe/personal computer network to a distributed workstation/personal computer local area network. The paper discusses computer hardware, mainframe computing, personal computers, mainframe/personal computer networks, workstations, transient analysis computer software, design/operation transient analysis codes, safety (licensed) analysis codes, cooperation with ABB-Atom, and customer support

  3. ABB and the global market

    International Nuclear Information System (INIS)

    Lindahl, G.

    1994-01-01

    Competing in a global environment implies that the authors previous business environment has been less than global, and there are indeed changes underway that lead to a more universal environment. But, there are still differences between regions and especially between the mature economies in the OECD countries and the rapidly developing countries, of which a majority are in Asia. For the OECD countries, the time after World War 2 and up to about 1970 was a period of unprecedented growth. Rebuilding after the war and a general growth of the use of electric power required high investments in power systems and caused a booming market for equipment suppliers. After a trend break in the beginning of the 1970s to less than 40 GW 10 years later, then slowly increased to about 50 GW today. At the same time, annual capacity growth in developing countries increased from less than 20 GW to about 50 GW, i.e. the same level as in OECD. This means that ABB is now passing a cross-over point: from now on less than half of their global market is in their well-known OECD world. And this share will continue to shrink. ABB is now restructuring to fulfill market needs in less developed, developing, and newly industrialized countries. This is the most important change in their global environment is addressed in this article

  4. ABB advanced BWR and PWR fuel

    International Nuclear Information System (INIS)

    Junkrans, S.; Helmersson, S.; Andersson, S.

    1999-01-01

    Fuel designed and fabricated by ABB is now operating in 40 PWRs and BWRs in Europe, the United States and Korea. An excellent fuel reliability track record has been established. High burnups are proven for both BWR and PWR. Thermal margin improving features and advanced burnable absorber concepts enable the utilities to adopt demanding duty cycles to meet new economic objectives. In particular we note the excellent reliability record of ABB PWR fuel equipped with Guardian TM debris filter, proven to meet the -6 rod-cycles fuel failure goal, and the out-standing operating record of the SVEA 10x10 BWR fuel, where ABB is the only vendor to date with multi batch experience to high burnup. ABB is dedicated to maintain high fuel reliability as well as continually improve and develop a broad line of BWR and PWR products. ABB's development and fuel follow-up activities are performed in close co-operation with its customers. (orig.)

  5. Forenklet programmering mot ABB-robot

    OpenAIRE

    Vasshus, Jan Marius

    2016-01-01

    Master's thesis in Computer science Kommunikasjon med ABB-robot utføres gjennom to grensesnitt, PC SDK og Robot Web Services. Disse grensesnittene er utviklet av ABB. Grensesnittene er store og inneholder mye funksjonalitet. Det kan være vanskelig å finne frem i grensesnittene, og vanskelig å vite hvordan programmeringen skal utføres. Dette fører til at de er tidkrevende å bli kjent. Denne oppgaven har som mål å forenkle programmering mot ABB-roboter ved å implementere et API som er byg...

  6. ABB PWR fuel design for high burnup

    International Nuclear Information System (INIS)

    Nilsson, S.; Jourdain, P.; Limback, M.; Garde, A.M.

    1998-01-01

    Corrosion, hydriding and irradiation induced growth of a based materials are important factors for the high burnup performance of PWR fuel. ABB has developed a number of Zr based alloys to meet the need for fuel that enables operation to elevated burnups. The materials include composition and processing optimised Zircaloy 4 (OPTIN TM ) and Zircaloy 2 (Zircaloy 2P), as well as advanced Zr based alloys with chemical compositions outside the composition specified for Zircaloy. The advanced alloys are either used as Duplex or as single component claddings. The Duplex claddings have an inner component of Zircaloy and an outer layer of Zr with small additions of alloying elements. ABB has furthermore improved the dimensional stability of the fuel assembly by developing stiffer and more bow resistant guide tubes while debris related fuel failures have been eliminated from ABB fuel by introducing the Guardian TM grid. Intermediate flow mixers that improve the thermal hydraulic performance and the dimensional stability of the fuel has also been developed within ABB. (author)

  7. BWR 90: The ABB advanced BWR design

    International Nuclear Information System (INIS)

    Haukeland, S.; Ivung, B.; Pedersen, T.

    1999-01-01

    ABB has two evolutionary advanced fight water reactors available today - the BWR 90 boiling water reactor and the System 80+ pressurised water reactor. The BWR 90 is based on the design, construction, commissioning and operation of the BWR 75 plants. The operation experience of the six plants of this advanced design has been very good. The average annual energy availability is above 90%, and the total power generation costs have been low. In the development of BWR 90 specific changes were introduced to the reference design, to adapt to technological progress, new safety requirements and to achieve cost savings. The thermal power rating of BWR 90 is 3800 MWth (providing a nominal 1374 MWe net), slightly higher dim that of the reference plant ABB Atom has taken advantage of margins gained using a new generation of its SVEA fuel to attain this power rating without major design modifications. The BWR 90 design was completed and offered to the TVO utility in Finland in 1991, as one of the contenders for the fifth Finnish nuclear power plant project. Thus, the design is available today for deployment in new plant projects. Utility views were incorporated through co-operation with the Finnish utility TVO, owner and operator of the two Olkiluoto plants of BWR 75 design. A review against the European Utility Requirement (EUR) set of requirements has been performed, since the design, in 1997, was selected by the EUR Steering Committee to be the first BWR to be evaluated against the EUR documents. The work is scheduled for completion in 1998. It will be the subject of an 'EUR Volume 3 Subset for BWR 90' document. ABB is continuing its BWR development work with the 'evolutionary' design BWR 90+. The primary design goal is to develop the BWR as a competitive option for the anticipated revival of the market for new nuclear plants beyond the turn of the century, as well as feeding ideas and inputs to the continuous modernisation efforts at operating plants. The development is

  8. ABB. CASE's GUARDIANTM Debris Resistant Fuel Assembly Design

    International Nuclear Information System (INIS)

    Dixon, D. J.; Wohlsen, W. D.

    1992-01-01

    ABB CE's experience, that 72% of all recent fuel-rod failures are caused by debris fretting, is typical. In response to this problem, ABB Combustion Engineering began supplying in the late 1980s fuel assemblies with a variety of debris resistant features, including both long-end caps and small flow holes. Now ABB CAE has developed an advanced debris resistant design concept, GUARDIAN TM , which has the advantage of capturing and retaining more debris than other designs, while displacing less plenum or active fuel volume than the long end-cap design. GUARDIAN TM design features have now been implemented into four different assembly designs. ABB CASE's GUARDIAN TM fuel assembly is an advanced debris-resistant design which has both superior filtering performance and uniquely, excellent debris retention, Retention effectively removes the debris from circulation in the coolant so that it is not able to threaten the fuel again. GUARDIAN TM features have been incorporated into four ABB. CAE fuel assembly designs. These assemblies are all fully compatible with the NSLS, and full-batch operation with GUARDIAN TM began in 1992. The number of plants of both CAE and non-CAE design which accept GUARDIAN TM for debris protection is expected to grow significantly during the next few years

  9. Corporate Social Responsibility for Competitiveness: A case study of ABB

    OpenAIRE

    Sturesson, Pauline; Eromosele, Joseph

    2014-01-01

    The effect of each CSR dimension on competitiveness is in different attribute importance. ABB emphasizes the integration of its CSR policy embedded in entrire five dimensions of CSR in different practices. The strongest, firmly established evidence of a positive effect of CSR on competitiveness appears in image/reputation dimension following by financial performance and innovation. Productivity and quality appeared less storng relations with CSR dimensions. Culture, a new dimension in CSR has...

  10. FRIGG '95. ABB Atom's upgraded T/H loop

    International Nuclear Information System (INIS)

    Noren, T.

    1995-01-01

    The FRIGG '95 project is an upgrading and modernization of the FRIGG loop, ABB Atom's fuel test rig with BWR operating conditions. The current FRIGG loop with test section and heater rods is described, together with the modifications involved in the FRIGG '95 project, including the new unique tomographic void measuring system to be installed. Finally CFD (Computational Fluid Dynamics) is introduced. (orig) (8 refs., 10 figs.)

  11. Development of an Abbe Error Free Micro Coordinate Measuring Machine

    Directory of Open Access Journals (Sweden)

    Qiangxian Huang

    2016-04-01

    Full Text Available A micro Coordinate Measuring Machine (CMM with the measurement volume of 50 mm × 50 mm × 50 mm and measuring accuracy of about 100 nm (2σ has been developed. In this new micro CMM, an XYZ stage, which is driven by three piezo-motors in X, Y and Z directions, can achieve the drive resolution of about 1 nm and the stroke of more than 50 mm. In order to reduce the crosstalk among X-, Y- and Z-stages, a special mechanical structure, which is called co-planar stage, is introduced. The movement of the stage in each direction is detected by a laser interferometer. A contact type of probe is adopted for measurement. The center of the probe ball coincides with the intersection point of the measuring axes of the three laser interferometers. Therefore, the metrological system of the CMM obeys the Abbe principle in three directions and is free from Abbe error. The CMM is placed in an anti-vibration and thermostatic chamber for avoiding the influence of vibration and temperature fluctuation. A series of experimental results show that the measurement uncertainty within 40 mm among X, Y and Z directions is about 100 nm (2σ. The flatness of measuring face of the gauge block is also measured and verified the performance of the developed micro CMM.

  12. Tilt Table Test

    Science.gov (United States)

    ... test may also be appropriate to investigate the cause of fainting if you've fainted only once, but another ... recommend a tilt table test to evaluate the cause of syncope. A tilt table test may also be recommended ...

  13. Rigorous modelling of light's intensity angular-profile in Abbe refractometers with absorbing homogeneous fluids

    International Nuclear Information System (INIS)

    García-Valenzuela, A; Contreras-Tello, H; Márquez-Islas, R; Sánchez-Pérez, C

    2013-01-01

    We derive an optical model for the light intensity distribution around the critical angle in a standard Abbe refractometer when used on absorbing homogenous fluids. The model is developed using rigorous electromagnetic optics. The obtained formula is very simple and can be used suitably in the analysis and design of optical sensors relying on Abbe type refractometry.

  14. Calculating the Weather: Deductive Reasoning and Disciplinary "Telos" in Cleveland Abbe's Rhetorical Transformation of Meteorology

    Science.gov (United States)

    Majdik, Zoltan P.; Platt, Carrie Anne; Meister, Mark

    2011-01-01

    This paper explores the rhetorical basis of a major paradigm change in meteorology, from a focus on inductive observation to deductive, mathematical reasoning. Analysis of Cleveland Abbe's "The Physical Basis of Long-Range Weather Forecasts" demonstrates how in his advocacy for a new paradigm, Abbe navigates the tension between piety to tradition…

  15. Tilting a Wobbly Chair

    Science.gov (United States)

    Cross, Rod

    2017-01-01

    If a small object is placed under the front leg of a chair, the chair tilts backwards. If the object is placed under a rear leg, the chair tilts sideways. The effect is surprising but can be analysed in terms of elementary physics.

  16. Application of ABB masterpiece systems for mine hoist control in North America

    Energy Technology Data Exchange (ETDEWEB)

    Kacy, K. (ABB, Montreal, PQ (Canada))

    1990-01-01

    Describes design and performance of mine hoist control equipment produced by the ABB manufacturer. The ABB Master hoist revamp equipment includes the Masterpiece MP-51, the MP-100 and the MP-200 control units. Scheme of equipment configuration, block diagram of hoist control, operation of the UHM-100 hoist monitoring unit and the Tyrak-L digital convertor are provided. Technical advantages of ABB systems are pointed out. The MP-100 and MP-200 systems include high capacity computer software permitting remote hoist control. At the Noranda-Geco mine (Canada) with a MP-200 system, one hoistman supervises operation of 3 mine shafts from one control room. Shafts are connected by a Masterbus 200 communication link. A list of 28 mines in the USA and Canada revamped by ABB systems is given.

  17. Open innovation at the Abbe School of Photonics

    Science.gov (United States)

    Helgert, Christian; Geiss, Reinhard; Nolte, Stefan; Eilenberger, Falk; Zakoth, David; Mauroner, Oliver; Pertsch, Thomas

    2017-08-01

    The Abbe School of Photonics (ASP) provides and coordinates the optics and photonics education of graduate and doctoral students at the Friedrich Schiller University in Jena, Germany. The internationalized Master's degree program is the key activity in training students in the optical sciences. The program is designed to provide them with the skills necessary to fill challenging positions in industry and academia. Here, an essential factor is ASP's close collaboration with more than 20 German photonics companies. To sustain these partners' future economic development, the availability of highly qualified employees is constantly required. Accordingly, these industrial partners, the European Union, the local state and the federal German government are strongly involved in the sustainable development of ASP's curriculum by both conceptual and financial engagements. The main goal is to promote the students' academic careers and job experience in the photonics industry as well as in academia. To open up the program to students from all over the world, all ASP lectures and courses are taught in English. ASP's qualification strategy is fully research-oriented and based on the principles of academic freedom, competitive research conditions and internationalization at all levels. The education program is complemented by a structured doctoral student support and a prestigious guest professorship program. Recently, ASP and partners have started a project to build an open photonics laboratory in order to foster innovative and co-creative processes. The idea follows well-established open innovation schemes e.g. in electronics. This Photon Garage (German: "Lichtwerkstatt") will bring together professionals and interested laymen from different backgrounds to approach pertinent challenges in photonics. Here, we will share our latest insights into the potentials and opportunities offered by this novel educative approach.

  18. ABB Turbo advanced fuel for application in System 80 family of plants

    International Nuclear Information System (INIS)

    Karoutas, Z.E.; Dixon, D.J.; Shapiro, N.L.

    1998-01-01

    ABB Combustion Engineering Nuclear Operations (ABB CE) has developed an Advanced Fuel Design, tailored to the Combustion Engineering, Inc. (CE) Nuclear Steam Supply System (NSSS) environment. This Advanced Fuel Design called Turbo features a full complement of innovative components, including GUARDIAN debris-resistant spacer grids, Turbo Zircaloy mixing grids to increase thermal margin and grid-to-rod fretting resistance, value-added fuel pellets to increase fuel loading, advanced cladding to increase achievable burnup, and axial blankets and Erbium integral burnable absorbers for improving fuel cycle economics. This paper summarizes the Turbo Fuel Design and its application to a System 80 family type plant. Benefits in fuel reliability, thermal margin, improved fuel cycle economics and burn up capability are compared relative to the current ABB CE standard fuel design. The fuel management design and the associated thermal margin are also evaluated. (author)

  19. Records in the desert. Good business relations of ABB Kraftwerke with the Gulf states; Rekorde in der Wueste. ABB Kraftwerke in den Golfstaaten gut im Geschaeft

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1996-08-01

    The Arabic region belongs to the particularly dynamic economic growth regions in the world. There is constantly growing demand for power plant capacity for power generation and drinking-water conditioning. ABB Kraftwerke AG, Mannheim, is successfully pursuing activities in this market. At Al Taweelah (Abu Dhabi), for instance, where the company heads a consortium, a power plant with the world-wide largest sea-water desalinification plant is being built. (orig.) [Deutsch] Der arabische Raum gehoert zu den besonders dynamischen Wachstumsregionen der Welt. Der Bedarf an Kraftwerkskapazitaet zur Stromerzeugung und Trinkwasserbereitung steigt kontinuierlich. Die ABB Kraftwerke AG, Mannheim, ist auf diesem Markt erfolgreich taetig. In Al Taweelah (Abu Dhabi) z.B. baut das Unternehmen als Konsortialfuehrer ein Kraftwerk mit der groessten Meerwasserentsalzungsanlage der Welt. (orig.)

  20. Rigidity of tilting modules

    DEFF Research Database (Denmark)

    Haahr Andersen, Henning; Kaneda, Masaharu

    Let $U_q$ denote the quantum group associated with a finite dimensional semisimple Lie algebra. Assume that $q$ is a complex root of unity of odd order and that $U_q$ is %the quantum group version obtained via Lusztig's $q$-divided powers construction. We prove that all regular projective (tilting...

  1. Use of ABB ADVANT Power for large scale instrumentation and controls replacements in nuclear power plants

    International Nuclear Information System (INIS)

    Pucak, J.L.; Brown, E.M.

    1999-01-01

    One of the major issues facing plants planning for life extension is the viability and feasibility of modernization of a plant's existing I and C systems including the safety systems and the control room. This paper discusses the ABB approach to the implementation of large scale Instrumentation and Controls (I and C) modernization. ABB applies a segmented architecture approach using the ADVANT Power control system to meet the numerous constraints of a major I and C upgrade program. The segmented architecture and how it supports implementation of a complete I and C upgrade either in one outage or in a series of outages is presented. ADVANT Power contains standardized industrial control equipment that is designed to support 1E applications as well as turbine and non-1E process control. This equipment forms the basis for the architecture proposed for future new nuclear plant sales as well as large scale retrofits. (author)

  2. Kinematic analysis of redundant robotic manipulators: application to Kuka LWR 4+ and ABB Yumi

    Directory of Open Access Journals (Sweden)

    Isiah Zaplana

    2018-03-01

    Full Text Available This paper presents a kinematic analysis of two redundant serial manipulators: Kuka LWR 4+ and ABB Yumi. This analysis includes the derivation of the forward kinematics for both manipulators as well as the solution of the inverse kinematic problem. For the Kuka LWR 4+ this solution is analytical whereas for the ABB Yumi an analytical and numerical approach is proposed. Besides, the singularities of the Kuka LWR 4+ are obtained symbolically and the singular directions associated are calculated. This study intends to increase the kinematic knowledge of two actual redundant manipulators as well as to provide valuable information that can be used in the definition of different algorithms or control laws.

  3. The Crystal Structure and Magnetic Behavior of Quinary Osmate and Ruthenate Double Perovskites LaABB'O6(A = Ca, Sr; B = Co, Ni; B' = Ru, Os).

    Science.gov (United States)

    Morrow, Ryan; McGuire, Michael A; Yan, Jiaqiang; Woodward, Patrick M

    2018-02-23

    Six LaABB'O 6 (A = Ca, Sr; B = Co, Ni; B' = Ru, Os) double perovskites were synthesized, several for the first time, and their crystal structures and magnetic behavior were characterized with neutron powder diffraction and direct-current and alternating-current magnetometry. All six compounds crystallize with P2 1 /n space group symmetry, resulting from a - a - c + octahedral tilting and complete rock salt ordering of transition-metal ions. Despite the electronic configurations of the transition-metal ions, either d 8 -d 3 or d 7 -d 3 , not one of the six compounds shows ferromagnetism as predicted by the Goodenough-Kanamori rules. LaSrNiOsO 6 , LaSrNiRuO 6 , and LaCaNiRuO 6 display long-range antiferromagnetic order, while LaCaNiOsO 6 , LaCaCoOsO 6 , and LaSrCoOsO 6 exhibit spin-glass behavior. These compounds are compared to the previously studied LaCaCoRuO 6 and LaSrCoRuO 6 , both of which order antiferromagnetically. The observed variations in magnetic properties can be attributed largely to the response of competing superexchange pathways due to changes in B-O-B' bond angles, differences in the radial extent of the 4d (B' = Ru) and 5d (B' = Os) orbitals, and filling of the t 2g orbitals of the 3d ion.

  4. Evaluating Tilt for Wind Plants

    Energy Technology Data Exchange (ETDEWEB)

    Annoni, Jennifer [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Scholbrock, Andrew K. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Churchfield, Matthew J. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Fleming, Paul A. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-07-03

    The objective of this work is to demonstrate the feasibility of tilt in a wind plant. Tilt control, much like other wind plant control strategies, has the potential to improve the performance of a wind plant. Tilt control uses the tilt angle of the turbine to direct the wake above or below the downstream turbines. This paper presents a study of tilt in two- and three-turbine arrays. Specifically, the authors show that the power production of a two-turbine array can be increased by tilting turbines in a specific orientation. When adding more turbines, as is shown with the three-turbine array, the overall percentage of power gain increases. This outcome deviates from some of the results seen in typical wind plant control strategies. Finally, we discuss the impact this type of control strategy has on the aerodynamics in a wind plant. This analysis demonstrates that a good understanding of wake characteristics is necessary to improve the plant's performance. A tilt strategy such as the one presented in this paper may have implications for future control/optimization studies including optimization of hub heights in a wind plant and analysis of deep array effects.

  5. Performance analysis of power swing blocking feature in ABB 670 series impedance relays

    Directory of Open Access Journals (Sweden)

    Maciej Łosiński

    2012-12-01

    Full Text Available This paper presents test results of a distance protection’s PSD power swing detection feature in ABB 670 series relays. A RED670 relay was tested, which is part of the hydroelectric set protection in Żarnowiec Pumped Storage Plant. The power swing blocking feature’s performance was analysed on the basis of the results of object tests made with an Omicron digital tester. Also presented are simulation results that illustrate the PSD feature’s response to power swings caused by a disturbance in the power system. It is also shown how a distance protection may react to the same fault, depending on its settings.

  6. How ABB Reaktor tackles inspection, repair and cleaning of SG tubes

    International Nuclear Information System (INIS)

    Lahner, K.

    1991-01-01

    Despite the large advances in the materials and chemistry used in nuclear power plants, steam generators remain a vulnerable component in the primary circuit of pressurized water reactors. The inspection, repair and the preventive maintenance of steam generator tubes are increasingly important technical disciplines. As part of its activities as a nuclear service company, ABB Reaktor has developed a family of tools and techniques that have been qualified and used for inspection and repair work on all types of steam generators. These include the remotely controlled DERI manipulator, eddy current testing equipment, removable plugs for tube repairs and two secondary side cleaning processes. (author)

  7. Quaternary oxides CaABB1O7 of zirconolite crystal structure

    International Nuclear Information System (INIS)

    Belyaev, I.N.; Aver'yanova, L.N.; Lopatin, S.S.

    1983-01-01

    Formation of quaternary oxides CaABB'O 7 of the composition at A=Ti, Zr, Hf, Sn, B=Al, Ga, Cr, Fe, In, B'=Sb, Nb, Ta is studied. Crystal zirconolite structure has been found in twelve samples containing gallium, ferrum (3) titanium, zirconium, hafnium, niobium, tantalum and antimony (5). In the cases, when A=Sn, B=Al quaternary oxides of the above composition are not formed. It is shown that zirconolite structure stability depends not only on cation dimensions but also on their electron structure

  8. La figure historique d’Ibn ‘Abbâs

    Directory of Open Access Journals (Sweden)

    Viviane Comerro

    2012-01-01

    Full Text Available ‘Abdallâh b. ‘Abbâs est l’une des hautes figures du savoir islamique constitué au premier siècle. Les diverses notices biographiques qui lui ont été consacrées dans les sources sunnites en témoignent à travers le portrait lisse et monochrome du Compagnon et du savant. Cependant, un autre portrait nous a été conservé, celui d’un homme partisan, au cœur de la mêlée qui oppose les différents clans de Quraysh dans la lutte pour le pouvoir. La figure dessinée par l’ouvrage édité sous le titre Akhbâr al-Dawla l-‘Abbâsiyya (ou quelques autres ouvrages du même genre échappe en grande partie à l’exemplum déshistoricisé des traditionnistes. Cet autre point de vue ne donne nullement à croire que l’auteur anonyme des ADA nous fournit une image plus authentiquement historique d’Ibn ‘Abbâs, mais il vient contredire la vision des religieux, ou celle des anthropologues, qui s’attachent à gommer l’accidentel dans le portrait stéréotypé. Certes, l’homme de chair et d’os, l’individu Ibn ‘Abbâs, nous échappe définitivement, mais sa figure historique peut-être pas. On peut, en effet, se demander si dans les informations rapportées par certains akhbâr, et qui relèvent de la recréation littéraire, ne se dissimule pas aussi la démarche réflexive de l’historien qui met en scène des faits en leur fournissant une explication. À la différence des traditionnistes qui ne se risquent dans le conflit que de façon allusive ou feutrée, les historiographes et leurs informateurs, des hommes souvent non répertoriés parce qu’ils n’appartiennent pas aux cercles de la riwâya, ne dissimulent pas les enjeux d’ordre historique. Quelques exemples empruntés aux ADA en sont donnés.

  9. BWR 90 and BWR 90+: Two advanced BWR design generations from ABB

    International Nuclear Information System (INIS)

    Haukeland, S.; Ivung, B.; Pedersen, T.

    1999-01-01

    ABB has two evolutionary advanced light water reactors available today - the BWR 90 boiling water reactor and the System 80+ pressurised water reactor. The BWR 90 is based on the design, construction, commissioning and operation of the BWR 75 plants. The operation experience of the six plants of this advanced design has been very good. The average annual energy availability is above 90%, and total power generation costs have been low. When developing the BWR 90 specific changes were introduced to a reference design, to adapt to technological progress, new safety requirements and to achieve cost savings. The thermal power rating of BWR 90 is 3800 MWth (providing a nominal 1374 MWe net), slightly higher than that of the reference plant ABB Atom has taken advantage of margins gained using a new generation of its SVEA fuel to attain this power rating without major design modifications. The BWR 90 design was completed and offered to the TVO utility in Finland in 1991, as one of the contenders for the fifth Finnish nuclear power plant project. Hence, the design is available today for deployment in new plant projects. Utility views were incorporated through co-operation with the Finnish utility TVO, owner and operator of the two Olkiluoto plants of BWR 75 design. A review against the European Utility Requirement (EUR) set of requirements has been performed, since the design, in 1997, was selected by the EUR Steering Committee to be the first BWR to be evaluated against the EUR documents. The review work was completed in 1998. It will be the subject of an 'EUR Volume 3 Subset for BWR 90' document. ABB is continuing its BWR development work with an 'evolutionary' design called BWR 90+, which aims at developing the BWR as a competitive option for the anticipated revival of the market for new nuclear plants beyond the turn of the century, as well as feeding ideas and inputs to the continuous modernisation efforts at operating plants. The development is performed by ABB Atom

  10. Source to Accretion Disk Tilt

    OpenAIRE

    Montgomery, M. M.; Martin, E. L.

    2010-01-01

    Many different system types retrogradely precess, and retrograde precession could be from a tidal torque by the secondary on a misaligned accretion disk. However, a source to cause and maintain disk tilt is unknown. In this work, we show that accretion disks can tilt due to a force called lift. Lift results from differing gas stream supersonic speeds over and under an accretion disk. Because lift acts at the disk's center of pressure, a torque is applied around a rotation axis passing through...

  11. Motion sickness on tilting trains.

    Science.gov (United States)

    Cohen, Bernard; Dai, Mingjia; Ogorodnikov, Dmitri; Laurens, Jean; Raphan, Theodore; Müller, Philippe; Athanasios, Alexiou; Edmaier, Jürgen; Grossenbacher, Thomas; Stadtmüller, Klaus; Brugger, Ueli; Hauser, Gerald; Straumann, Dominik

    2011-11-01

    Trains that tilt on curves can go faster, but passengers complain of motion sickness. We studied the control signals and tilts to determine why this occurs and how to maintain speed while eliminating motion sickness. Accelerometers and gyros monitored train and passenger yaw and roll, and a survey evaluated motion sickness. The experimental train had 3 control configurations: an untilted mode, a reactive mode that detected curves from sensors on the front wheel set, and a predictive mode that determined curves from the train's position on the tracks. No motion sickness was induced in the untilted mode, but the train ran 21% slower than when it tilted 8° in either the reactive or predictive modes (113 vs. 137 km/h). Roll velocities rose and fell faster in the predictive than the reactive mode when entering and leaving turns (0.4 vs. 0.8 s for a 4°/s roll tilt, P<0.001). Concurrently, motion sickness was greater (P<0.001) in the reactive mode. We conclude that the slower rise in roll velocity during yaw rotations on entering and leaving curves had induced the motion sickness. Adequate synchronization of roll tilt with yaw velocity on curves will reduce motion sickness and improve passenger comfort on tilting trains.

  12. Secondary bilateral cleft lip-nose deformity correction by rhinoplasty with simultaneous Abbe flap

    Directory of Open Access Journals (Sweden)

    Nitin J Mokal

    2014-01-01

    Full Text Available Aim: The purpose of this article is to review modification and outcome of secondary rhinoplasty along with Abbι flap for correction of secondary bilateral cleft lip deformity. Materials and Methods: A total of thirteen patients of secondary bilateral cleft lip-nose deformity having tight upper lip, lack of acceptable philtral column, Cupid′s bow definition, irregular lip scars, and associated nasal deformity were selected. All the patients received Abbι flap and simultaneous nasal correction. All cases were treated during a period of three years. Mean patient age at the time of the operation was 21 years, and ranged from 16 to 27 years. The average follow-up period was three years. Results: Assessment of results was based on comparing preoperative and postoperative clinical photographs done by surgeon and patient relatives and patient satisfaction questionnaires. The columellar lengthening and upper lip vermillion correction achieved was satisfactory. There were no perioperative complications such as airway obstruction, bleeding, infection, wound disruption, or flap necrosis.

  13. ABB.-Combustion Engineering's Experience in Nuclear Power Plant Engineering and Construction in Korea

    International Nuclear Information System (INIS)

    Veris, James W.

    1992-01-01

    The Yonggwang Nuclear Project is a milestone project for the Korean Nuclear Industry. The Project has the two objectives of obtaining self-reliance in all aspects of nuclear technology and of constructing two modern nuclear power plants under the leadership of Korean companies acting as prime contractors. ABB.-Combustion Engineering 1000 MW System 80+ TM was chosen in 1987 as the NSLS design to meet these two objectives. This paper summarizers the significant experiences and lessons learned through the first four years of the Project as well as identifying implications for such future projects. The unique challenges of the project are identified and an evaluation of the experiences in the technology, self-reliance program and in the design and manufacturing processes will be made

  14. Athermalization and achromatization of visible/SWIR optics using instantaneous Abbe number

    Science.gov (United States)

    Ramsey, J. L.

    2017-11-01

    With the move to more and more lightweight and cost-effective design, a move to multiband or multi-spectral optics is required. These systems are becoming more prevalent in the market as new detector technologies have been developed. However, the lens designs are only starting to be considered with the addition of new materials in the MWIR and the LWIR. For the VIS/SWIR region the designs have been possible, but a lack of detector technology has resulted in few designs being considered for actual manufacturing. These designs are also difficult due to changes in the Abbe number in the different wavebands. Where the glass map is robust in the visible region, there exists a lack of crown glasses in the SWIR, and one is left with mostly flint glasses. This proves challenging from a chromatic perspective. The challenge becomes even more difficult if one wants to incorporate athermalization.

  15. Tilting Saturn without Tilting Jupiter: Constraints on Giant Planet Migration

    Science.gov (United States)

    Brasser, R.; Lee, Man Hoi

    2015-11-01

    The migration and encounter histories of the giant planets in our solar system can be constrained by the obliquities of Jupiter and Saturn. We have performed secular simulations with imposed migration and N-body simulations with planetesimals to study the expected obliquity distribution of migrating planets with initial conditions resembling those of the smooth migration model, the resonant Nice model and two models with five giant planets initially in resonance (one compact and one loose configuration). For smooth migration, the secular spin-orbit resonance mechanism can tilt Saturn’s spin axis to the current obliquity if the product of the migration timescale and the orbital inclinations is sufficiently large (exceeding 30 Myr deg). For the resonant Nice model with imposed migration, it is difficult to reproduce today’s obliquity values, because the compactness of the initial system raises the frequency that tilts Saturn above the spin precession frequency of Jupiter, causing a Jupiter spin-orbit resonance crossing. Migration timescales sufficiently long to tilt Saturn generally suffice to tilt Jupiter more than is observed. The full N-body simulations tell a somewhat different story, with Jupiter generally being tilted as often as Saturn, but on average having a higher obliquity. The main obstacle is the final orbital spacing of the giant planets, coupled with the tail of Neptune’s migration. The resonant Nice case is barely able to simultaneously reproduce the orbital and spin properties of the giant planets, with a probability ˜ 0.15%. The loose five planet model is unable to match all our constraints (probability <0.08%). The compact five planet model has the highest chance of matching the orbital and obliquity constraints simultaneously (probability ˜0.3%).

  16. Height and Tilt Geometric Texture

    DEFF Research Database (Denmark)

    Andersen, Vedrana; Desbrun, Mathieu; Bærentzen, Jakob Andreas

    2009-01-01

    compromise between functionality and simplicity: it can efficiently handle and process geometric texture too complex to be represented as a height field, without having recourse to full blown mesh editing algorithms. The height-and-tilt representation proposed here is fully intrinsic to the mesh, making...

  17. ABB-CE2s System 80+ advanced light water reactor design

    International Nuclear Information System (INIS)

    Flynn, E. P.

    1994-01-01

    This presentation will focus on the evolutionary improvements that have been made to System 80 which is the current operating design that was selected as the basis for developing System 80+. The Electric Power Research Institute (EPRI) has developed and issued the Advanced Light Water Reactor (ALWR) requirements as the basis for future ALWR's. ABB-CE and its associates were active participants in the development of the ALWR design requirements. System 80+ development has been in accordance with the EPRI requirements and System 80+ is the only Evolutionary Pressurized Water Reactor design to these requirements. The System 80+ design currently is in the final stages of NRC review leading to certification as a complete power plant1 Nuclear Island, Turbine lsland, and Balance of Plant, which are integrated for safe and reliable operation. Improved safety is a major feature of System 80+ with redundancy and diversity providing a prudent balance between accident prevention and mitigation. Safety Injection and Emergency Feedwater are dedicated four-train systems. The containment structure is a large spherical steel vessel surrounded by a cylindrical concrete shield building. The entire nuclear Island is founded on a common basemat to provide seismic resistance. The Nuclear Steam Supply System design has incorporated increased margin and improved reliability. High technology focused the control complex on the human operator. Programmable logic controllers, distributed system architecture, super mini-computers, fiber optic communications, touch sensitive cathode ray tube and advanced signal validation tecniques greatly simplify the design

  18. Perbaikan Pengelolaan Pergudangan Melalui Penerapan Sistem Informasi Pergudangan di CV. ABB

    Directory of Open Access Journals (Sweden)

    Hery Hamdi Azwir

    2017-05-01

    Full Text Available Warehousing management problems that exist in the CV. ABB is the management of warehouses that are susceptible to manipulation of data, methods of work are still very manual such as recording a spare part only handwritten by the warehouse, frequent loss of spare parts in the warehouse, the bon false, and the lack of supervision instruments for oversee the spare parts in the warehouse. To overcome these problems, then made improvements through the implementation of warehouse management information system. Improvements in the form of procurement supervision instruments using the application PHP7 and MySQL, because the existence of the application makes it easy to keep an eye on spare parts in the warehouse, ranging from spare part comes in, spare part out, anyone who requests a part, stock of spare parts of existing in the warehouse, stock outs are used to help finance the manufacture purchase order, reports the spare parts that go into the warehouse of the supplier and request a report part. Not only is it a system of warehousing information can facilitate in making purchase order finance and carry out the approval of the request part of the user. Thus the system becomes more transparent.

  19. Problems of urban violence: The case of Boulevard Macta in Sidi Bel Abbes

    Directory of Open Access Journals (Sweden)

    Lamia Khadidja Beghdoud

    2018-03-01

    Full Text Available In Algeria, for some decades, the architecture has undergone a certain turn, switching into the infernal cycle where the buildings are ultra-secure. The fear exacerbated by the numerous attacks (robberies, rapes, murders has led the state but also individuals to protect themselves by constructing otherwise. Sidi Bel Abbes is known in western Algeria by a large number of aggression and robberies. We chose the Macta boulevard as a case study where we asked ourselves about the architectural metamorphosis of buildings that faces urban violence and its impact on the urban landscape. In order to answer this question, we have adopted three approaches that are primarily historical through the study of the stratification of the neighborhood. Next, the landscape approach through the study of metomorphic urban environment. Finally, social through the study of practices, representations and the appropriation of space. It turns out that this district which dates from the colonial era has undergone many changes through the removal of the entrance garden, the placement of metal grilles at the window level, the removal of the dwelling at the level of the ground floor, the raising of fence walls and placement of barbed wire. These actions have disfigured this district.

  20. Internationalized and research-oriented photonics education: Abbe School of Photonics

    Science.gov (United States)

    Helgert, Christian; Nolte, Stefan; Pertsch, Thomas

    2015-10-01

    The Abbe School of Photonics (ASP) provides and coordinates the optics and photonics education of graduate and doctoral students at the Friedrich Schiller University in Jena, Germany. The internationalized Master's degree program is the key activity in training students in the optical sciences. The program is designed to provide them with the skills necessary to fill challenging positions in industry and academia. Here, an essential factor is ASP's close collaboration with more than 20 German photonics companies. To sustain these partners' future economic development, the availability of highly qualified employees is constantly required. Accordingly, these industrial partners, the European Union, the local state and the federal German government are strongly involved in the sustainable development of ASP's curriculum by both conceptual and financial engagements. The main goal is to promote the students' academic careers and job experience in the photonics industry as well as in academia. To open up the program to students from all over the world, all ASP lectures and courses are taught in English. Since 2009, more than 250 graduate students from more than 40 different countries have been enrolled at the School. Almost 90% of them of non-German nationality, fulfilling the essential ASP philosophy to locally establish an international education program. ASP's qualification strategy is fully research-oriented and based on the principles of academic freedom, competitive research conditions and internationalization at all levels. The education program is complemented by a structured doctoral student support and a prestigious guest professorship program.

  1. Increasing ABB FlexPicker Robot’s Degree of Freedom (DOF using Flexible End Effector

    Directory of Open Access Journals (Sweden)

    Nordin M. H.

    2016-01-01

    Full Text Available The commissioning of a high speed parallel robot such as the ABB Flexpicker Robot into the industrial environment provides greater flexibility in picking, packaging or palletizing tasks. However, current configuration of this robot only allows up to four-degree-of-freedom (DOF which restricted its function to perform simple or complex automated assembly task. Therefore, the possibility of increasing one additional degree-of-freedom for the parallel robot was investigated. By attaching a flexible vacuum hose to the robot’s end effector, it can be controlled by using a servomotor that can manipulate its angle of suction up to 90 degrees. With this new configuration, one DOF has been introduced for this robot. Several tests had been conducted to evaluate the flexibility and performance of the end effector which includes varying loads and angles. From the analysis, it is found that the end-effector can lift weights up to 1kg due to sufficient vacuum pressure; however, it could perform bending up to 90 degrees for maximum load of 600 grams only.

  2. Confirmatory Survey Results For Portions Of The ABB Combustion Engineering Site In Windsor, Connecticut During The Fall Of 2011

    International Nuclear Information System (INIS)

    Adams, Wade C.

    2011-01-01

    From the mid-1950s until mid-2000, the Combustion Engineering, Inc. (CE) site in Windsor, Connecticut (Figure A-1) was involved in the research, development, engineering, production, and servicing of nuclear fuels, systems, and services. The site is currently undergoing decommissioning that will lead to license termination and unrestricted release in accordance with the requirements of the License Termination Rule in 10 CFR Part 20, Subpart E. Asea Brown Boveri Incorporated (ABB) has been decommissioning the CE site since 2001.

  3. "CONFIRMATORY SURVEY RESULTS FOR THE ABB COMBUSTION ENGINEERING SITE WINDSOR, CONNECTICUT DCN 5158-SR-02-2

    Energy Technology Data Exchange (ETDEWEB)

    ADAMS, WADE C

    2013-03-25

    The objectives of the confirmatory activities were to provide independent contractor field data reviews and to generate independent radiological data for use by the NRC in evaluating the adequacy and accuracy of the contractor's procedures and FSS results. ORAU reviewed ABB CE's decommissioning plan, final status survey plan, and the applicable soil DCGLs, which were developed based on an NRC-approved radiation dose assessment. The surveys include gamma surface scans, gamma direct measurements, and soil sampling.

  4. CONFIRMATORY SURVEY RESULTS FOR PORTIONS OF THE ABB COMBUSTION ENGINEERING SITE IN WINDSOR, CONNECTICUT DURING THE FALL OF 2011

    Energy Technology Data Exchange (ETDEWEB)

    Wade C. Adams

    2011-12-09

    From the mid-1950s until mid-2000, the Combustion Engineering, Inc. (CE) site in Windsor, Connecticut (Figure A-1) was involved in the research, development, engineering, production, and servicing of nuclear fuels, systems, and services. The site is currently undergoing decommissioning that will lead to license termination and unrestricted release in accordance with the requirements of the License Termination Rule in 10 CFR Part 20, Subpart E. Asea Brown Boveri Incorporated (ABB) has been decommissioning the CE site since 2001.

  5. A DNA mimic: the structure and mechanism of action for the anti-repressor protein AbbA.

    Science.gov (United States)

    Tucker, Ashley T; Bobay, Benjamin G; Banse, Allison V; Olson, Andrew L; Soderblom, Erik J; Moseley, M Arthur; Thompson, Richele J; Varney, Kristen M; Losick, Richard; Cavanagh, John

    2014-05-01

    Bacteria respond to adverse environmental conditions by switching on the expression of large numbers of genes that enable them to adapt to unfavorable circumstances. In Bacillus subtilis, many adaptive genes are under the negative control of the global transition state regulator, the repressor protein AbrB. Stressful conditions lead to the de-repression of genes under AbrB control. Contributing to this de-repression is AbbA, an anti-repressor that binds to and blocks AbrB from binding to DNA. Here, we have determined the NMR structure of the functional AbbA dimer, confirmed that it binds to the N-terminal DNA-binding domain of AbrB, and have provided an initial description for the interaction using computational docking procedures. Interestingly, we show that AbbA has structural and surface characteristics that closely mimic the DNA phosphate backbone, enabling it to readily carry out its physiological function. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Molecular tilt on monolayer-protected nanoparticles

    KAUST Repository

    Giomi, L.

    2012-02-01

    The structure of the tilted phase of monolayer-protected nanoparticles is investigated by means of a simple Ginzburg-Landau model. The theory contains two dimensionless parameters representing the preferential tilt angle and the ratio ε between the energy cost due to spatial variations in the tilt of the coating molecules and that of the van der Waals interactions which favors the preferential tilt. We analyze the model for both spherical and octahedral particles. On spherical particles, we find a transition from a tilted phase, at small ε, to a phase where the molecules spontaneously align along the surface normal and tilt disappears. Octahedral particles have an additional phase at small ε characterized by the presence of six topological defects. These defective configurations provide preferred sites for the chemical functionalization of monolayer-protected nanoparticles via place-exchange reactions and their consequent linking to form molecules and bulk materials. Copyright © EPLA, 2012.

  7. Conservative treatment of excessive anterior pelvic tilt

    DEFF Research Database (Denmark)

    Brekke, Anders Falk

    , DK-5000 Odense C, Denmark ABSTRACT (1795 anslag) Background: Excessive anterior pelvic tilt has been linked to pain and dysfunction of the hip and pelvic region. Conservative treatment (e.g. manual therapy and physical training) is suggested in correcting the tilt and eventually related symptoms....... However, the effectiveness in reducing excessive anterior pelvic tilt in adults is unknown. Purpose: To systematically review studies investigating the effectiveness of conservative treatment in reducing anterior pelvic tilt in adults and evaluate the quality of evidence. Materials and methods: MEDLINE...

  8. Capacitive micromachined ultrasonic transducer based tilt sensing

    Science.gov (United States)

    Yu, Hongbin; Guo, Bin; Haridas, Kuruveettil; Lin, Tsu-Hui; Hao Cheong, Jia; Lin Tsai, Ming; Boon Yee, Tack

    2012-10-01

    In this paper, a tilt sensing mechanism based on the capacitive micromachined ultrasound transducers (CMUTs) is presented. By measuring the difference in the time of flight of various pulse-echo signals from different CMUT transmitting elements to one common receiving element in the oil bath, the tilt angle of the oil surface can be determined. With the proposed device, the maximum tilt angles of 20° and 28° have been measured in the clockwise and counterclockwise directions, respectively, and the difference between the measured and the theoretical values of the tilt angle was found to be within 0.05° during the whole test.

  9. Optic flow induced self-tilt perception

    NARCIS (Netherlands)

    Bos, J.E.

    2008-01-01

    Roll optic flow induces illusory self-tilt in humans. As far as the mechanism underlying this visual-vestibular interaction is understood, larger angles of self-tilt are predicted than observed. It is hypothesized that the discrepancy can be explained by idiotropic (i.e., referring to a personal

  10. Lake-tilting investigations in southern Sweden

    International Nuclear Information System (INIS)

    Paasse, T.

    1996-04-01

    The main aim of lake-tilting investigations is to determine the course of the glacio-isostatic uplift, i.e. to find a formula for the uplift. Besides the lake-tilting graphs, knowledge of the recent relative uplift and the gradient of some marine shorelines are used for solving this problem. This paper summarizes four investigations. 23 refs, 10 figs

  11. Lake-tilting investigations in southern Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Paasse, T. [Sveriges Geologiska Undersoekning, Goeteborg (Sweden)

    1996-04-01

    The main aim of lake-tilting investigations is to determine the course of the glacio-isostatic uplift, i.e. to find a formula for the uplift. Besides the lake-tilting graphs, knowledge of the recent relative uplift and the gradient of some marine shorelines are used for solving this problem. This paper summarizes four investigations. 23 refs, 10 figs.

  12. Large optics inspection, tilting, and washing stand

    Science.gov (United States)

    Ayers, Marion Jay [Brentwood, CA; Ayers, Shannon Lee [Brentwood, CA

    2010-08-24

    A large optics stand provides a risk free means of safely tilting large optics with ease and a method of safely tilting large optics with ease. The optics are supported in the horizontal position by pads. In the vertical plane the optics are supported by saddles that evenly distribute the optics weight over a large area.

  13. Monitoring of temperature-mediated phase transitions of adipose tissue by combined optical coherence tomography and Abbe refractometry.

    Science.gov (United States)

    Yanina, Irina Y; Popov, Alexey P; Bykov, Alexander V; Meglinski, Igor V; Tuchin, Valery V

    2018-01-01

    Observation of temperature-mediated phase transitions between lipid components of the adipose tissues has been performed by combined use of the Abbe refractometry and optical coherence tomography. The phase transitions of the lipid components were clearly observed in the range of temperatures from 24°C to 60°C, and assessed by quantitatively monitoring the changes of the refractive index of 1- to 2-mm-thick porcine fat tissue slices. The developed approach has a great potential as an alternative method for obtaining accurate information on the processes occurring during thermal lipolysis. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  14. Otestovaní komunikace po IEC61850 s využitím GOOSE mezi ABB a Siemens ochranou

    OpenAIRE

    Vavreczky, Gábor

    2012-01-01

    Hlavním úkolem této diplomové práce je seznámit se s možnostmi spolupráce IED od společností ABB a Siemens podle IEC61850. Cílem práce je vytvoření a otestování pracovního postupu, po kterém ochrany od ABB a Siemens budou mezi sebou komunikovat prostřednictvím GOOSE zpráv. Tato práce se k tomu poskytuje popis standardu IEC61850, jako teoretický základ. Podrobně se zabývá konfigurací ochran Siprotec 7SA610 podle IEC61850. Dále jsou popsány konfigurační nástroje PCM600 a IET600, které slouží pr...

  15. Evaluating Tilt for Wind Farms: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Annoni, Jennifer; Scholbrock, Andrew; Churchfield, Matthew; Fleming, Paul

    2017-06-29

    The objective of this work is to demonstrate the feasibility of tilt in a wind plant. Tilt control, much like other wind plant control strategies, has the potential to improve the performance of a wind plant. Tilt control uses the tilt angle of the turbine to direct the wake above or below the downstream turbines. This paper presents a study of tilt in two- and threeturbine arrays. Specifically, the authors show that the power production of a two-turbine array can be increased by tilting turbines in a specific orientation. When adding more turbines, as is shown with the three-turbine array, the overall percentage of power gain increases. This outcome deviates from some of the results seen in typical wind plant control strategies. Finally, we discuss the impact this type of control strategy has on the aerodynamics in a wind plant. This analysis demonstrates that a good understanding of wake characteristics is necessary to improve the plant's performance. A tilt strategy such as the one presented in this paper may have implications for future control/optimization studies including optimization of hub heights in a wind plant and analysis of deep array effects.

  16. Unilateral otolith centrifugation by head tilt.

    Science.gov (United States)

    Winters, Stephanie M; Bos, Jelte E; Klis, Sjaak F L

    2014-01-01

    To test for otolith asymmetries, several studies described horizontal translation of the body and head en bloc during fast vertical axis rotation. This stimulus causes one otolithic organ to rotate on-axis, and the other to experience centripetal acceleration. To test a new, more simple method of unilateral stimulation with head tilt and the body remaining on axis. During stationary and during 360 deg/s rotation, 12 healthy blindfolded subjects had their heads tilted 30 degrees sideways, positioning one otolithic organ on the axis of rotation after the other. The haptic subjective vertical (SV) was recorded several times by means of a manually adjustable rod. It was found that during stationary the SV tilted about 4 degrees on average in the direction of the head. During rotation, the SV tilted about 9 degrees on average. We therefore estimate the effect of eccentric otolith rotation to be 5 degrees on average. Tilt of the subjective vertical induced by head tilt during on-axis body rotation can provide a relatively uncomplicated alternative to test unilateral otolithic function as compared to body and head translation during rotation. Moreover, unlike eccentric rotation of the entire body, somatosensory cues are minimized by keeping the body fixed on axis and by subtracting the effect of head tilt per se.

  17. Experimental studies of octahedral tilting in perovskites

    International Nuclear Information System (INIS)

    Howard, C.J.; Kennedy, B.J.; Chakoumakos, B.C.

    1999-01-01

    Full text: Structures of the perovskite family, ABX 3 , have interested crystallographers over many years, and continue to attract attention on account of their fascinating electrical and magnetic properties, and their significance in the earth sciences. The ideal perovskite (cubic) is a particularly simple structure, but also a demanding one, since aside from the lattice parameter there are no variable parameters in the structure. Consequently, the majority of perovskite structures show departures from the ideal, the most common distortion being the comer-linked tilting of the practically rigid BX 6 octahedral units. Following a group theoretical study in 1997, a number of experimental investigations of octahedral tilting have been undertaken in 1998, and these are reported in this presentation. The studies are of the perovskites, SrZrO 3 , SrHfO 3 , CaTiO 3 , NaTaO 3 and LaGaO 3 . In each case, the crystal structures have been followed at high temperatures, with particular attention being paid to temperature regimes in which only the simplest octahedral tilt (only one tilt axis) pertains. Neutron powder diffraction patterns have been recorded on the medium/high resolution diffractometer installed at beam port HB4 at the High Flux Isotope Reactor, at the Oak Ridge National Laboratory. Crystal structures have been refined by the Rietveld method, and angles of tilt of the oxygen octahedra derived from the atomic position parameters. Each of the first four perovskites listed above transforms from tetragonal (with a single tilt axis) to cubic, and in each case, as far as can be determined from our measurements, the tilt angle in the tetragonal phase decreases continuously towards zero. There are interesting differences, however, in the functional form of this variation. The LaGaO 3 transforms at modest temperature to a rhombohedral phase, also characterised by a single tilt axis, but though the tilt angle decreases slowly with increasing temperature, the sample

  18. Sensor fusion for structural tilt estimation using an acceleration-based tilt sensor and a gyroscope

    Science.gov (United States)

    Liu, Cheng; Park, Jong-Woong; Spencer, B. F., Jr.; Moon, Do-Soo; Fan, Jiansheng

    2017-10-01

    A tilt sensor can provide useful information regarding the health of structural systems. Most existing tilt sensors are gravity/acceleration based and can provide accurate measurements of static responses. However, for dynamic tilt, acceleration can dramatically affect the measured responses due to crosstalk. Thus, dynamic tilt measurement is still a challenging problem. One option is to integrate the output of a gyroscope sensor, which measures the angular velocity, to obtain the tilt; however, problems arise because the low-frequency sensitivity of the gyroscope is poor. This paper proposes a new approach to dynamic tilt measurements, fusing together information from a MEMS-based gyroscope and an acceleration-based tilt sensor. The gyroscope provides good estimates of the tilt at higher frequencies, whereas the acceleration measurements are used to estimate the tilt at lower frequencies. The Tikhonov regularization approach is employed to fuse these measurements together and overcome the ill-posed nature of the problem. The solution is carried out in the frequency domain and then implemented in the time domain using FIR filters to ensure stability. The proposed method is validated numerically and experimentally to show that it performs well in estimating both the pseudo-static and dynamic tilt measurements.

  19. CT patellar cortex tilt angle: A radiological method to measure patellar tilt

    International Nuclear Information System (INIS)

    Mirza Toluei, F.; Afshar, A.; Salarilak, S.; Sina, A.

    2005-01-01

    Background/Objectives: the role of patellar tilt in the anterior knee pain is indisputable. Traditionally. the lateral patello-femoral angle of Laurin has been defined in both the axial view and CT images for measuring the tilt of patella. We present a new angle. which is independent of the morphology of patella and directly relates to clinical assessment of the tilt. which is appreciated from palpation of the edges of the patella. Patients and Methods: 38 patients with anterior knee pain and forty normal control subjects were examined using CT scan of patello-femoral joint in 15 degrees of knee flexion. The amount of lateral patellar tilt was quantitatively assessed using the lateral patello-femoral angle, as described by Laurin et al, and the newly defined patellar cortex tilt angle. This angle is subtended by the line drawn along the posterior femoral condyles and the one parallel to the subchondral bone of patellar cortex. The fifteen-degree tilt was taken as normal cut-off point for patellar cortex tilt angle in the control group. Results: in patients, the average tilt of patella. using the patellar cortex tilt angle was 15.26 versus 7.05 in the control group. Using Student's t test, the difference between the two means was significant (P<0.001). The sensitivity and specificity of patellar cortex tilt angle were 40 and 90 percent, respectively There was a moderate agreement between our presented test and the lateral tilt angle test (kappa=0.40. P<0.001). Conclusion: our results indicate that patellar tilt can also be detected using patellar cortex tilt angle. We need more specific studies ta determine the validity of the test

  20. Conservative treatment of excessive anterior pelvic tilt

    DEFF Research Database (Denmark)

    Brekke, Anders Falk

    quality by two reviewers using Cochrane Collaboration’s tool for assessing risk of bias in RCT’s and the ROBINS-I tool (Risk Of Bias In Non-randomized Studies - of interventions). Data was synthesized qualitatively. The GRADE approach was used to determine the overall quality of the evidence. PROSPERO...... treatment may reduce anterior pelvis tilt and reduce symptoms in relation to faulty posture. Keywords: pelvis, anterior tilt, anteversion, posture...

  1. Lifting to cluster-tilting objects in higher cluster categories

    OpenAIRE

    Liu, Pin

    2008-01-01

    In this note, we consider the $d$-cluster-tilted algebras, the endomorphism algebras of $d$-cluster-tilting objects in $d$-cluster categories. We show that a tilting module over such an algebra lifts to a $d$-cluster-tilting object in this $d$-cluster category.

  2. M. Mangard, "Le Sanctuaire gallo-romain du Bois l’Abbé à Eu (Seine-Maritime"

    Directory of Open Access Journals (Sweden)

    Alain Ferdière

    2010-02-01

    Full Text Available Il s’agit en fait de la publication de fouilles déjà ancienne – ce qui n’enlève évidemment rien, au contraire, aux mérites de cet ouvrage : les recherches sur le site du “ Bois-L’Abbé ” à Eu (Seine-Maritime ont en effet été conduites dans les années 1960/70 par l’auteur, et seulement complétées par quelques plus récents sondages, à l’occasion de travaux de mise en valeur, seulement en partie pris en compte ici.Il en résulte un volume présentant, à la forme comme au fond, un caractère vieillo...

  3. CITEQ creates a transformer for underground electric networks: a joint initiative by Hydro-Quebec and ABB

    International Nuclear Information System (INIS)

    Cordeau, P.

    1997-01-01

    Advances in technology regarding underground transformers was discussed. After more than 3 years of research, CITEQ (Centre d'innovation sur le transport d'energie du Quebec), a new company founded by Hydro-Quebec and ABB, is on the verge of a breakthrough with a new submersible transformer with solid insulation. This transformer was specially designed for use in underground electric networks. The new transformer is a good alternative to conventional oil transformers which have a high risk of pollution mainly due to corrosion, leaks, explosions or fires. Also, the outer shell of the new transformer is composed of composite material which will eliminate the need for maintenance. The service life of the new transformer is expected to be approximately 30 to 40 years. CITEQ is hoping that this new technology will benefit the residential sector which is powered by underground distribution networks. 1 fig

  4. Le roman cinéraire d’Octave Mirbeau : L’Abbé Jules

    OpenAIRE

    Ziegler, Robert

    2017-01-01

    En plus d’une attaque des institutions sociales qui engendrent des névroses et étouffent la spontanéité, L’Abbé Jules de Mirbeau est un péan au caractère éphémère de l’art. L’œuvre accomplie devrait être un objet modeste, passager, se dissipant dans sa réception, à l’image de ces pans de charogne animale dont Jules dit qu’ils sont perdus à jamais dans la forêt, et que là, ils « disparaissent, volatilisés dans les choses ».Liant les fins polémiques et esthétiques de son roman, Mirbeau conclut ...

  5. Direct cone beam SPECT reconstruction with camera tilt

    International Nuclear Information System (INIS)

    Jianying Li; Jaszczak, R.J.; Greer, K.L.; Coleman, R.E.; Zongjian Cao; Tsui, B.M.W.

    1993-01-01

    A filtered backprojection (FBP) algorithm is derived to perform cone beam (CB) single-photon emission computed tomography (SPECT) reconstruction with camera tilt using circular orbits. This algorithm reconstructs the tilted angle CB projection data directly by incorporating the tilt angle into it. When the tilt angle becomes zero, this algorithm reduces to that of Feldkamp. Experimentally acquired phantom studies using both a two-point source and the three-dimensional Hoffman brain phantom have been performed. The transaxial tilted cone beam brain images and profiles obtained using the new algorithm are compared with those without camera tilt. For those slices which have approximately the same distance from the detector in both tilt and non-tilt set-ups, the two transaxial reconstructions have similar profiles. The two-point source images reconstructed from this new algorithm and the tilted cone beam brain images are also compared with those reconstructed from the existing tilted cone beam algorithm. (author)

  6. Spatial coherence profilometry on tilted surfaces

    Czech Academy of Sciences Publication Activity Database

    Pavlíček, Pavel; Halouzka, M.; Duan, Z.; Takeda, M.

    2009-01-01

    Roč. 48, č. 34 (2009), H40-H47 ISSN 0003-6935 R&D Projects: GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100522 Keywords : tilted surface * spatial coherence profilometry * spatial coherence * measurement error * shape measurement Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.410, year: 2009

  7. "Happiness and Education": Tilting at Windmills?

    Science.gov (United States)

    Verducci, Susan

    2013-01-01

    This essay explores the question: Is Nel Noddings a visionary who sees past the constraints of contemporary education or is she, like Don Quixote, madly tilting at windmills in her description and defense of happiness as an educational aim? Viewing the educational aim of happiness as an ideal raises substantial challenges for the practicality of…

  8. Effect of Cement and Compaction on the Physicochemical Behavior of a Material in the Region of Sidi Bel Abbes

    Directory of Open Access Journals (Sweden)

    N. S. Ikhlef

    2014-08-01

    Full Text Available Soil treatment describes the procedure under which a soil acquires certain characteristics that did not originally have. This paper is focused in the field of road earthworks and the treatment of a material found in the region of Sidi Bel Abbes, Algeria. This material has poor characteristics that do not meet the standards used in road geotechnics. To remedy this, firstly, the Proctor Standard characteristics of this material were improved using mechanical treatment that increased the compaction energy. Then a chemical treatment was employed, adding some cement dosages, and results show that the material classified in the A1h class, for an increased maximum dry density and a reduction in water content. A comparative study is made on the optimal properties of the material between the two modes of treatment. On the other hand, after treatment, one finds a decrease in the plasticity index and the methylene blue value. This material exhibits a change of class. Therefore, soil class CL turned into a soil class CL-ML (silt of low plasticity. This observation allows the material to be used as backfill or subgrade.

  9. Spread of Cooking Bananas (Musa spp., genome ABB in a Traditional Plantain-Growing Area in Southeast Nigeria

    Directory of Open Access Journals (Sweden)

    Ezedinma, C.

    2002-01-01

    Full Text Available The study examined the level and rate of spread of cooking bananas (Musa spp., ABB genome to determine their success among the farmers. They were introduced in Southeastern Nigeria in the mid-1980s by the International Institute of Tropical Agriculture (IITA as an interim measure to reduce the incidence of black sigatoka disease on plantains. Data were collected, using a structured questionnaire, from 285 randomly selected farmers in 76 villages. Results of the study indicate that about 60% of the respondents have given out suckers to other fellow-farmers. On average, every "diffuser" distributed 8 cooking banana suckers to 5 new fellow-farmers. Primary and secondary diffusions accounted for 59% and 61% respectively; while inter-village diffusion accounted for about 50% of the movement of the suckers. The study also found that the demand for the crop has been increasing since its introduction in the region. These results indicate a high level of diffusion of the crop considering its newness in the region and that it is well accepted. They also suggest that the crop has the potential of supplementing plantain in food and income generation for the farmers in the region.

  10. Kommunicera - Att förmedla en möjlighet : En studie av den interna kommunikationen på ABB Sverige i Västerås

    OpenAIRE

    Lindberg, Petra; Eriksson, Ida

    2011-01-01

    Title: Communicate – to provide an opportunity Authors: Ida Eriksson & Petra Lindberg Tutor: Johan Grinbergs, Mälardalen University Examiner: Cecilia Lindh Subject: Bachelor's essay, Business Administration Keywords: communication, internal communication, channels, communication models, communication theory, information, organization Purpose The idea of this study was to describe how ABB Sweden’s internal communication and information appeared in Västerås. The aim is also to see what too...

  11. Development of tilted fibre Bragg gratings using highly coherent 255 ...

    Indian Academy of Sciences (India)

    2014-02-06

    Feb 6, 2014 ... This paper reports the study on development of tilted fibre Bragg gratings using highly coherent 255 nm radiation, obtained from the second harmonic generation (SHG) of copper vapour laser (CVL). The transmission and reflection spectra of the tilted fibre Bragg gratings (TFBG) were studied for the tilt ...

  12. Development of a metrological atomic force microscope with minimized Abbe error and differential interferometer-based real-time position control

    International Nuclear Information System (INIS)

    Ducourtieux, Sebastien; Poyet, Benoit

    2011-01-01

    A metrological atomic force microscope (mAFM) has been developed at LNE. It will be dedicated to traceable dimensional measurements and calibrations of transfer standards with a maximum size of 25 mm × 25 mm × 7 mm. The displacement range is 60 µm for the X and Y axes and 15 µm for the Z axis. The instrument uses four laser differential interferometers in an original Abbe-compliant arrangement to measure the position of the tip relative to the sample and to be directly traceable to the SI. The expected uncertainty for the measurement of the tip/sample relative position is 1 nm for the whole range without taking into account the tip contribution. To fulfill this specification, the design of the instrument has been optimized to minimize Abbe errors, to reduce the metrology loop length, to limit the drifts due to thermal dilatation and to improve the stability of interferometric position measurement in ambient air. To limit Abbe errors, a dedicated three-axis flexure stage has been developed to reduce parasitic rotational motion at the level of 1 µrad for the whole range. This stage is driven by piezo-actuators. The instrument controller is based on a FPGA combined with an embedded PXI controller to perform real-time control of the XYZ position. We present the design of the instrument and the very first results

  13. Design and Development of Tilting Rotary Furnace

    Science.gov (United States)

    Sai Varun, V.; Tejesh, P.; Prashanth, B. N.

    2018-02-01

    Casting is the best and effective technique used for manufacturing products. The important accessory for casting is furnace. Furnace is used to melt the metal. A perfect furnace is one that reduces the wastage of material, reduces the cost of manufacturing and there by reduces the cost of production. Of all the present day furnaces there may be wastage of material, and the chances of increasing the time of manufacturing as the is continuous need of tilting of the furnace for every mould and then changing the moulds. Considering these aspects, a simple and least expensive tilting rotary furnace is designed and developed. The Tilting and Rotary Furnace consists of mainly melting chamber and the base. The metal enters the melting chamber through the input door that is provided on the top of the melting chamber. Inside the melting chamber there is a graphite furnace. The metal is melted in the graphite crucible. An insulation of ceramic fibre cloth is provided inside the furnace. The metal is melted using Propane gas. The propane gas is easily available and economic. The gas is burned using a pilot burner. The pilot burner is more efficient that other burners. The pilot burner is lit with a push button igniter. The pilot burner is located at the bottom of the combustion chamber. This enables the uniform heating of the metal inside the crucible. The temperature inside the melting chamber is noted using a temperature sensor. The gas input is cut-off if the temperature is exceeding a specific temperature. After the melting of the metal is done the furnace is tilted and after the mould is filled it is rotated. The external gears are used to controlling the tilting. The results of studies carried out for the design & development of low cost, simple furnace that can be mounted anywhere on the shop floor and this can be very much useful for the education purposes and small scale manufacturing. The furnace can be rotated in 360 degrees and can help in reducing the time taken

  14. Determinants of Motion Sickness in Tilting Trains: Coriolis/Cross-Coupling Stimuli and Tilt Delay.

    Science.gov (United States)

    Bertolini, Giovanni; Durmaz, Meek Angela; Ferrari, Kim; Küffer, Alexander; Lambert, Charlotte; Straumann, Dominik

    2017-01-01

    Faster trains require tilting of the cars to counterbalance the centrifugal forces during curves. Motion sensitive passengers, however, complain of discomfort and overt motion sickness. A recent study comparing different control systems in a tilting train, suggested that the delay of car tilts relative to the curve of the track contributes to motion sickness. Other aspects of the motion stimuli, like the lateral accelerations and the car jitters, differed between the tested conditions and prevented a final conclusion on the role of tilt delay. Nineteen subjects were tested on a motorized 3D turntable that simulated the roll tilts during yaw rotations experienced on a tilting train, isolating them from other motion components. Each session was composed of two consecutive series of 12 ideal curves that were defined on the bases of recordings during an actual train ride. The simulated car tilts started either at the beginning of the curve acceleration phase (no-delay condition) or with 3 s of delay (delay condition). Motion sickness was self-assessed by each subject at the end of each series using an analog motion sickness scale. All subjects were tested in both conditions. Significant increases of motion sickness occurred after the first sequence of 12 curves in the delay condition, but not in the no-delay condition. This increase correlated with the sensitivity of motion sickness, which was self-assessed by each subject before the experiment. The second sequence of curve did not lead to a significant further increase of motion sickness in any condition. Our results demonstrate that, even if the speed and amplitude are as low as those experienced on tilting trains, a series of roll tilts with a delay relative to the horizontal rotations, isolated from other motion stimuli occurring during a travel, generate Coriolis/cross-coupling stimulations sufficient to rapidly induce motion sickness in sensitive individuals. The strength and the rapid onset of the motion

  15. Determinants of Motion Sickness in Tilting Trains: Coriolis/Cross-Coupling Stimuli and Tilt Delay

    Directory of Open Access Journals (Sweden)

    Giovanni Bertolini

    2017-05-01

    Full Text Available Faster trains require tilting of the cars to counterbalance the centrifugal forces during curves. Motion sensitive passengers, however, complain of discomfort and overt motion sickness. A recent study comparing different control systems in a tilting train, suggested that the delay of car tilts relative to the curve of the track contributes to motion sickness. Other aspects of the motion stimuli, like the lateral accelerations and the car jitters, differed between the tested conditions and prevented a final conclusion on the role of tilt delay. Nineteen subjects were tested on a motorized 3D turntable that simulated the roll tilts during yaw rotations experienced on a tilting train, isolating them from other motion components. Each session was composed of two consecutive series of 12 ideal curves that were defined on the bases of recordings during an actual train ride. The simulated car tilts started either at the beginning of the curve acceleration phase (no-delay condition or with 3 s of delay (delay condition. Motion sickness was self-assessed by each subject at the end of each series using an analog motion sickness scale. All subjects were tested in both conditions. Significant increases of motion sickness occurred after the first sequence of 12 curves in the delay condition, but not in the no-delay condition. This increase correlated with the sensitivity of motion sickness, which was self-assessed by each subject before the experiment. The second sequence of curve did not lead to a significant further increase of motion sickness in any condition. Our results demonstrate that, even if the speed and amplitude are as low as those experienced on tilting trains, a series of roll tilts with a delay relative to the horizontal rotations, isolated from other motion stimuli occurring during a travel, generate Coriolis/cross-coupling stimulations sufficient to rapidly induce motion sickness in sensitive individuals. The strength and the rapid onset

  16. Listening talkers produce great spectral tilt contrasts

    DEFF Research Database (Denmark)

    Christiansen, Thomas Ulrich; Heegård, Jan; Henrichsen, Peter Juel

    It is well known that the envelope of the long-term average speech spectrum flattens with vocal effort. A recent study [1] showed that content words had a flatter spectral envelope than content words at the same overall level for a specific Danish speech material. The present paper investigates...... of colored geometrical shapes taken from DanPASS [2]. The spectral tilt was gauged by calculating the band-level difference in dB between two frequency bands with pass-bands 150 to 803 Hz and 803 to 1358 Hz respectively in 5 ms intervals. This was done separately for intervals containing content words...... and function words and grouped by talker. The spectral tilt difference was then calculated as the average band-level difference for function words minus the average band-level difference for content words. This calculation was grouped per talker. For the monologues these differences ranged between 5 and 8 d...

  17. A tilted transversely isotropic slowness surface approximation

    KAUST Repository

    Stovas, A.

    2012-05-09

    The relation between vertical and horizontal slownesses, better known as the dispersion relation, for transversely isotropic media with a tilted symmetry axis (TTI) requires solving a quartic polynomial equation, which does not admit a practical explicit solution to be used, for example, in downward continuation. Using a combination of the perturbation theory with respect to the anelliptic parameter and Shanks transform to improve the accuracy of the expansion, we develop an explicit formula for the vertical slowness that is highly accurate for all practical purposes. It also reveals some insights into the anisotropy parameter dependency of the dispersion relation including the low impact that the anelliptic parameter has on the vertical placement of reflectors for a small tilt in the symmetry angle. © 2012 European Association of Geoscientists & Engineers.

  18. Inverse solutions for tilting orthogonal double prisms.

    Science.gov (United States)

    Li, Anhu; Ding, Ye; Bian, Yongming; Liu, Liren

    2014-06-10

    An analytical reverse solution and actual examples are given to show how to direct a laser beam from a pair of orthogonal prisms to given targets in free space. Considering the influences of double-prism structural parameters, a lookup table method to seek the numerical reverse solution of each prism's tilting angle is also proposed for steering the double-prism orientation to track a target position located in the near field. Some case studies, as well as a specified elliptical target trajectory scanned by the cam-based driving double prisms, exhibit the significant application values of the theoretical derivation. The analytic reverse and numerical solutions can be generalized to investigate the synthesis of scanning patterns and the controlling strategy of double-prism tilting motion, the potentials of which can be explored to perform the orientation and position tracking functions in applications of precision engineering fields.

  19. GAS MOVEMENT IN ROTARY TILTING FURNACES

    Directory of Open Access Journals (Sweden)

    S. L. Rovin

    2016-01-01

    Full Text Available The article presents the results of studies of gas movement and heat and mass transfer processes in the rotary tilting furnace (RTF at the heat treatment of disperse materials. The study was performed through computer modeling using software packages ANSYS CFX and Solid Works Flow Simulation. The results were used to design RTF with different capacity and application and helped to improve their technical and economic characteristics.

  20. Temperature characteristics of tilted wave lasers

    Science.gov (United States)

    Maximov, Mikhail V.; Gordeev, Nikita Yu.; Shernyakov, Yuri M.; Payusov, Alexey S.; Kalyuzhnyy, Nikolay A.; Mintairov, Sergey A.; Kulagina, Marina M.; Zhukov, Alexey E.; Shchukin, Vitaly A.; Ledentsov, Nikolai N.

    2016-11-01

    We report on the temperature characteristics of edge-emitting tilted wave lasers (TWL) composed of a thin active waveguide (0.7 μm) optically coupled to a thick passive waveguide (26 μm). The active region is based on four 1040-nm InGaAs/GaAs quantum wells. The 2-mm-long and 50-μm-wide broad area lasers show characteristic temperature of 115 K and lasing up to 120°C in the continuous-wave mode. The maximal pulsed output power as high as 40 W was achieved being limited by the available current source. Vertical far-fields of the TWLs consist of two tilted narrow lobs (2.4 deg full width at half maximum each), which contain >70% of the total output power. The tilt angle of the lobes slightly increases with the temperature (by 1 deg/40°C) due to the transverse mode hopping caused by the temperature-induced changes of the waveguide refractive indices.

  1. A COMMON SOURCE OF ACCRETION DISK TILT

    International Nuclear Information System (INIS)

    Montgomery, M. M.; Martin, E. L.

    2010-01-01

    Many different system types retrogradely precess, and retrograde precession could be from a tidal torque by the secondary on a misaligned accretion disk. However, a source that causes and maintains disk tilt is unknown. In this work, we show that accretion disks can tilt due to a force called lift. Lift results from differing gas stream supersonic speeds over and under an accretion disk. Because lift acts at the disk's center of pressure, a torque is applied around a rotation axis passing through the disk's center of mass. The disk responds to lift by pitching around the disk's line of nodes. If the gas stream flow ebbs, then lift also ebbs and the disk attempts to return to its original orientation. To first approximation, lift does not depend on magnetic fields or radiation sources but does depend on the mass and the surface area of the disk. Also, for disk tilt to be initiated, a minimum mass transfer rate must be exceeded. For example, a 10 -11 M sun disk around a 0.8 M sun compact central object requires a mass transfer rate greater than ∼ 8 x 10 -11 M sun yr -1 , a value well below the known mass transfer rates in cataclysmic variable dwarf novae systems that retrogradely precess and exhibit negative superhumps in their light curves and a value well below mass transfer rates in protostellar-forming systems.

  2. Thermal annealing of tilted fiber Bragg gratings

    Science.gov (United States)

    González-Vila, Á.; Rodríguez-Cobo, L.; Mégret, P.; Caucheteur, C.; López-Higuera, J. M.

    2016-05-01

    We report a practical study of the thermal decay of cladding mode resonances in tilted fiber Bragg gratings, establishing an analogy with the "power law" evolution previously observed on uniform gratings. We examine how this process contributes to a great thermal stability, even improving it by means of a second cycle slightly increasing the annealing temperature. In addition, we show an improvement of the grating spectrum after annealing, with respect to the one just after inscription, which suggests the application of this method to be employed to improve saturation issues during the photo-inscription process.

  3. An efficient eikonal solver for tilted transversely isotropic and tilted orthorhombic media

    KAUST Repository

    Waheed, Umair bin

    2014-01-01

    Computing first-arrival traveltimes in the presence of anisotropy is important for high-end near surface modeling, microseismic source localization, and fractured reservoir characterization. Anisotropy deviating from elliptical anisotropy introduces higher-order nonlinearity into the eikonal equation, which makes solving the equation a challenging task. We address this challenge by iteratively solving a sequence of simpler tilted elliptically anisotropic eikonal equations. At each iteration, the source function is updated to capture the effects due to the higher order nonlinear terms in the anisotropy. We use Aitken extrapolation to speed up the convergence rate of the iterative algorithm. The result is an efficient algorithm for firstarrival traveltime computations in tilted anisotropic media. We demonstrate the proposed method for the tilted transversely isotropic media and the tilted orthorhombic media. Numerical tests show that the proposed method is feasible and produces results that are comparable to wavefield extrapolation, even for strongly anisotropic and complex structures. Therefore, for the cases where one or two-point ray tracing fails, our method may be a potential substitute for computing traveltimes.

  4. Rotating Shaft Tilt Angle Measurement Using an Inclinometer

    OpenAIRE

    Luo Jun; Wang Zhiqian; Shen Chengwu; Wen Zhuoman; Liu Shaojin; Cai Sheng; Li Jianrong

    2015-01-01

    This paper describes a novel measurement method to accurately measure the rotating shaft tilt angle of rotating machine for alignment or compensation using a dual-axis inclinometer. A model of the rotating shaft tilt angle measurement is established using a dual-axis inclinometer based on the designed mechanical structure, and the calculation equation between the rotating shaft tilt angle and the inclinometer axes outputs is derived under the condition that the inclinometer axes are perpendic...

  5. Effect of tilting on oxygenation in newborn infants.

    Science.gov (United States)

    Thoresen, M; Cowan, F; Whitelaw, A

    1988-01-01

    Transcutaneous (tc) PO2 in newborn infants increased on head up tilting (median increase 0.5 kPa at term, 1.0 kPa preterm). Head down tilting was associated with an equivalent fall in tcPO2. There was no change in tcPCO2. Tilting of infants mechanically ventilated for respiratory distress syndrome or surgery produced no consistent change in PO2. PMID:3128187

  6. Numerical modelling of the tilt casting processes of titanium alumindes

    OpenAIRE

    Wang, Hong

    2008-01-01

    This research has investigated the modelling and optimisation of the tilt casting process of Titanium Aluminides (TiAl). This study is carried out in parallel with the experimental research undertaken in IRC at the University of Birmingham. They propose to use tilt casting inside a vacuum chamber and attempt to combine this tilt casting process with Induction Skull Melting (ISM). A totally novel process is developing for investment casting, which is suitable for casting gamma TiAl.\\ud \\ud As ...

  7. Ethylene production and quality in 1-Methylcyclopropene treated 'Abbé Fètel'pears after storage in Dynamically Controlled Atmosphere

    NARCIS (Netherlands)

    Vanoli, M.; Eccher Zerbini, P.C.; Grassi, M.; Rizzolo, A.

    2010-01-01

    This research studies the ethylene production rate (EP) and quality in 1-MCP treated ‘Abbé Fètel’ pears after storage in DCA compared to NA and CA. 1-MCP treated (300 ppb) and control fruit were stored at -0.5°C in NA, CA (2 kPa O2 + 0.7 kPa CO2) and DCA (0.7 kPa O2 + 0.3 kPa CO2). After 4 and 6

  8. INVESTIGATIONS ON OPERATION OF ROTARY TILTING FURNACES

    Directory of Open Access Journals (Sweden)

    S. L. Rovin

    2016-01-01

    Full Text Available Rotary tilting furnace (RTF is a new type of fuel furnaces, that provide the most efficient heating and recycling of polydisperse materials. The paper describes results of the investigations on thermal processes in the RTF, movement of materials and non-isothermal gas flow during kiln rotary process. The investigations have been carried out while using physical and computer simulations and under actual operating conditions applying the pilot plant. Results of the research have served as a basis for development of recommendations on the RTF calculations and designing and they have been also used for constructional design of a rotary tilting furnace for heating and melting of cast iron chips, reduction smelting of steel mill scale, melting of aluminum scrap, melting of lead from battery scrap. These furnaces have a high thermal efficiency (~50 %, technological flexibility, high productivity and profitability. Proven technical solutions for recycling of ferrous and non-ferrous metals develop the use of RTF in the foundry and metallurgical industry as the main technological unit for creation of cost-effective small-tonnage recycling of metal waste generated at the plants. The research results open prospects for organization of its own production for high-quality charging material in Belarus in lieu of imported primary metal. The proposed technology makes it possible to solve environmental challenge pertaining to liquidation of multi-tonnage heaps of metal-containing wastes.

  9. Mapping of moveout in tilted transversely isotropic media

    KAUST Repository

    Stovas, A.

    2013-09-09

    The computation of traveltimes in a transverse isotropic medium with a tilted symmetry axis tilted transversely isotropic is very important both for modelling and inversion. We develop a simple analytical procedure to map the traveltime function from a transverse isotropic medium with a vertical symmetry axis (vertical transversely isotropic) to a tilted transversely isotropic medium by applying point-by-point mapping of the traveltime function. This approach can be used for kinematic modelling and inversion in layered tilted transversely isotropic media. © 2013 European Association of Geoscientists & Engineers.

  10. Transient cardio-respiratory responses to visually induced tilt illusions

    Science.gov (United States)

    Wood, S. J.; Ramsdell, C. D.; Mullen, T. J.; Oman, C. M.; Harm, D. L.; Paloski, W. H.

    2000-01-01

    Although the orthostatic cardio-respiratory response is primarily mediated by the baroreflex, studies have shown that vestibular cues also contribute in both humans and animals. We have demonstrated a visually mediated response to illusory tilt in some human subjects. Blood pressure, heart and respiration rate, and lung volume were monitored in 16 supine human subjects during two types of visual stimulation, and compared with responses to real passive whole body tilt from supine to head 80 degrees upright. Visual tilt stimuli consisted of either a static scene from an overhead mirror or constant velocity scene motion along different body axes generated by an ultra-wide dome projection system. Visual vertical cues were initially aligned with the longitudinal body axis. Subjective tilt and self-motion were reported verbally. Although significant changes in cardio-respiratory parameters to illusory tilts could not be demonstrated for the entire group, several subjects showed significant transient decreases in mean blood pressure resembling their initial response to passive head-up tilt. Changes in pulse pressure and a slight elevation in heart rate were noted. These transient responses are consistent with the hypothesis that visual-vestibular input contributes to the initial cardiovascular adjustment to a change in posture in humans. On average the static scene elicited perceived tilt without rotation. Dome scene pitch and yaw elicited perceived tilt and rotation, and dome roll motion elicited perceived rotation without tilt. A significant correlation between the magnitude of physiological and subjective reports could not be demonstrated.

  11. Specificity of head-up tilt testing in adolescents: effect of various degrees of tilt challenge in normal control subjects.

    Science.gov (United States)

    Lewis, D A; Zlotocha, J; Henke, L; Dhala, A

    1997-10-01

    This study sought to determine the specificity of commonly used tilt protocols in children. Tilt table testing is commonly utilized in the evaluation of children and adolescents with syncope despite a lack of uniformity in tilt protocols and a lack of studies of specificity in normal control subjects. Sixty-nine normal control volunteers (12 to 18 years old, 38 male, 31 female) with no previous history of syncope, presyncope or arrhythmia underwent tilting to 80 degrees, 70 degrees or 60 degrees for a maximum of 30 min on a motorized table with a footboard support. Autonomic maneuvers, including deep breathing, carotid massage, Valsalva maneuver and diving reflex, were performed before tilt testing to determine whether the response to these maneuvers could identify subjects prone to fainting during tilt testing. Symptoms of presyncope and frank syncope were elicited in 24 of 69 subjects (13 male, 11 female): 6 (60%) of 10 were tilted at 80 degrees, 9 (29%) of 31 at 70 degrees and 9 (32%) of 28 at 60 degrees. Tilt testing at 80 degrees was terminated after the tenth subject by the institutional review board. The mean time to a positive test response was 10.5 min at 80 degrees, 14.2 min at 70 degrees and 13.2 min at 60 degrees. In the 80 degrees tilt, 4 of 10 subjects had a positive response within 10 minutes, whereas only 3 of 31 and 2 of 28 had a positive response within testing were similar with respect to age; gender; PR, QRS and QT intervals; and baseline heart rate and blood pressure. Likewise, responses to other autonomic function tests performed were similar in tilt-positive and tilt-negative patients. The power for detecting a significant difference between patients tilted at 80 degrees versus 60 degrees and 70 degrees was 0.45 and for detecting differences in autonomic tone between tilt-positive (n = 24) and tilt-negative (n = 45) subjects was 0.8. Children appear to be more susceptible to orthostatic stress than adults. Therefore, tilt protocols commonly

  12. A patient treated with tilt training and midodrine after 68 seconds asystole during head-up tilt table testing.

    Science.gov (United States)

    Oz, Fahrettin; Cizgici, Yaşar; Bilge, A Kaya

    2011-08-01

    Neurocardiogenic syncope is a relatively common cause of syncope and is diagnosed by head-up tilt testing. A 21-year-old man was examined for frequent syncope episodes which occurred after episodes of blood drawing and standing in queue. Syncope developed in tilt table testing. After about 68 seconds, sinus rhythm returned. Recent reports have shown that tilt training is a very effective therapy for recurrent neurocardiogenic syncope. In our case, the patient was treated with midodrine 2.5 mg once a day and a tilt training programme. Therapy resulted in improvement and during a follow-up of six months, no major events occurred.

  13. Using collisions and resonances to tilting Uranus

    Science.gov (United States)

    Rogoszinski, Zeeve; Hamilton, Douglas

    2018-01-01

    Uranus’ large obliquity (98°) is widely thought to have occurred from a polar strike with an Earth sized object. Morbidelli et al. (2012) argue that two or more collisions are required in order to explain the prograde motion of Uranus’ satellites. These impactors could have been less massive by about a factor of ten, but multiple polar strikes are still improbable as even larger mass impactors would be needed for more equatorial collisions. Here we explore an alternative non-collisional model inspired by the explanation to Saturn’s significant tilt (27°). Ward and Hamilton (2004) & Hamilton and Ward (2004) argue that a secular resonance currently between Saturn’s spin axis and Neptune’s orbital pole is responsible for Saturn’s large obliquity. Unfortunately, Uranus’ axial precession frequency today is too long to match any of the current planets’ fundamental frequencies. Boué and Laskar (2010) explain that Uranus may have harbored an improbably large moon in the past which could have sped up the planet’s axial precession frequency enough to resonate with the regression of its own orbital pole. We explore another scenario which requires only the interactions between the giant planets.Thommes et al. (1999, 2002, 2003) argue that at least the cores of Uranus and Neptune were formed in between Jupiter and Saturn, as the density of the protoplanetary disk was greater there. If Neptune was scattered outward before Uranus, then a secular spin-orbit resonance between the two planets is possible. However, driving Uranus’ obliquity to near 90° with a resonance capture requires a timescale on the order of 100 Myr. If Neptune migrated out quicker or its orbital inclination was initially larger, then we find that the resulting resonance kick can tilt Uranus more than 40° in a reasonable timespan. This could replace one of the impactors required in the collisional scenario described by Morbidelli et al. (2012), but in most situations the effect of such a

  14. Oral rehabilitation with tilted dental implants: A metaanalysis

    Science.gov (United States)

    Peñarrocha-Oltra, David; Candel-Marti, Eugenia; Peñarrocha-Diago, Maria

    2012-01-01

    Objective: To compare the course of patients treated with tilted implants versus those treated conventionally with axial implants, analyzing the success rate and marginal bone loss. Material and Methods: A PubMed search was made using the key words “tilted implants”, “angled implants”, “angulated implants”, “inclined implants” and “maxillary atrophy.” A review was made of the articles published between 1999-2010. The inclusion criteria were the use of tilted implants, clinical series involving at least 10 patients, and a minimum follow-up of 12 months after prosthetic loading. The exclusion criteria were isolated clinical cases, studies with missing data, and publications in languages other than English or Spanish. The metaanalysis finally included 13 articles: 7 retrospective studies and 6 prospective studies. Results: On analyzing the success rate in the retrospective studies, two reported a higher success rate with tilted implants; one a higher success rate with axial implants; and two reported similar success rates with both implants. On analyzing the success rate in the prospective studies, two reported a higher success rate with tilted implants; two a higher success rate with axial implants; and two reported similar success rates with both implants. On examining marginal bone loss, three studies reported greater bone loss with axial implants and one with tilted implants. Conclusions: There was no evidence of differences in success rate between tilted and axial implants in either the prospective or retrospective studies subjected to review. The marginal bone loss observed with the tilted and axial implants likewise proved very similar. It thus can be deduced that tilted implants exhibit the same evolutive behavior as axial implants. Key words:Axial implants, tilted implants, maxillary atrophy, tilted implants. PMID:22322494

  15. Lens decenter and tilt measurement by interferogram

    Science.gov (United States)

    Hung, Min-Wei; Wu, Wen-Hong; Huang, Kuo-Cheng

    2009-11-01

    For the recent years, the vigorous development of the electro-optic industry, particularly the digital camera and the cellular phone camera, has placed a larger and larger demand for the optical devices. Among the optical lens, the aspherical optical lens plays the key component because the aspherical lens may provide better imaging quality then the spherical lens does. For the manufacturing reason, the aspherical lens is prone to a decenter or tilt issue with respect to the optical axes of its two surfaces. To measure decenter and tile error specifically would help to obviate the deficient lens, but most of the present measuring method can't provide this function. This paper proposed a new method to specifically measure the decenter and tile of lens by observing the interferogram of each surface. And the corresponding measuring instrument, which contains interferometer and motion stages, was introduced as well.

  16. Tilted-ring modelling of disk galaxies : Anomalous gas

    NARCIS (Netherlands)

    Jozsa, G. I. G.; Niemczyk, C.; Klein, U.; Oosterloo, T. A.

    We report our ongoing work on kinematical modelling of HI in disk galaxies. We employ our new software TiRiFiC (Tilted-Ring-Fitting-Code) in order to derive tilted-ring models by fitting artificial HI data cubes to observed ones in an automated process. With this technique we derive very reliable

  17. Downward continuation and tilt derivative of magnetic data for ...

    Indian Academy of Sciences (India)

    S K Pal

    2017-06-12

    Jun 12, 2017 ... The present study deals with the characterization of subsurface coal fires of East Basuria colliery in. Jharia coal field, India using tilt derivative and downward continuation of magnetic data. Magnetic data processing methods such as diurnal correction, noise removal, reduction to pole, tilt derivative and.

  18. Ion kinetic effects on the tilt mode in FRCs

    International Nuclear Information System (INIS)

    Schwarzmeier, J.L.; Seyler, C.E.; Barnes, D.C.

    1981-01-01

    Theory and simulations have shown that field reversed configurations (FRG's) should be unstable magnetohydrodynamically to the tilting mode, yet tilting seldom is seen in the experiments. Profile effects (within MHD) and ion finite larmor radius (FLR) effects have been prosed to explain the observed stability of FRC's. The present work seeks to test both of these effects

  19. Angular momentum projection of tilted axis rotating states

    Energy Technology Data Exchange (ETDEWEB)

    Oi, M.; Onishi, N.; Tajima, N. [Tokyo Univ. (Japan); Horibata, T.

    1998-03-01

    We applied an exact angular momentum projection to three dimensional cranked HFB (3d-CHFB) states. Tilted axis rotating states (TAR) and principal axis rotating states (PAR) are compared. It is shown that TAR is more adequate than PAR for description of the back bending phenomena driven by tilted rotation or wobbling motion. (author)

  20. Orientation and alignment in beam tilted-foil spectroscopy

    International Nuclear Information System (INIS)

    Berry, H.G.

    1976-01-01

    The production of atomic orientation and alignment, by anisotropic excitation is analyzed. The stokes parameters of the light emitted from tilted-foil excited ions provide measurements of orientation and alignment, and some examples are given. The variations of the stokes parameters with foil tilt angle, excited state, ion velocity and foil material are compared with existing theories

  1. A tilting wind tunnel for fire behavior studies

    Science.gov (United States)

    David R. Weise

    1994-01-01

    The combined effects of wind velocity and slope on wildland fire behavior can be studied in the laboratory using a tilting wind tunnel. The tilting wind tunnel requires a commercially available fan to induce wind and can be positioned to simulate heading and backing fires spreading up and down slope. The tunnel is portable and can be disassembled for transport using a...

  2. Development of tilted fibre Bragg gratings using highly coherent 255 ...

    Indian Academy of Sciences (India)

    2014-02-06

    Feb 6, 2014 ... coupling of the guided modes shifts to the long wavelength as the tilt angle is increased. [3]. The central wavelength and the reflectivity of a TFBG are dependent on the angle. Due to the presence of tilt angle, the transmission spectra of TFBGs exposed in air con- sisted of multiple resonance peaks occurred ...

  3. Tilting of trucks: a driver education system and warning system

    NARCIS (Netherlands)

    Kleuskens, R.J.A.

    1996-01-01

    To reduce the risk of tilting, TNO has developed a tilt warning system for commercial vehicles. This system is able to monitor vehicle weight, lateral acceleration and velocity during normal operation. The system CPU is constantly comparing the measured lateral acceleration to a calculated limit

  4. Motion perception during tilt and translation after space flight

    Science.gov (United States)

    Clément, Gilles; Wood, Scott J.

    2013-11-01

    Preliminary results of an ongoing study examining the effects of space flight on astronauts' motion perception induced by independent tilt and translation motions are presented. This experiment used a sled and a variable radius centrifuge that translated the subjects forward-backward or laterally, and simultaneously tilted them in pitch or roll, respectively. Tests were performed on the ground prior to and immediately after landing. The astronauts were asked to report about their perceived motion in response to different combinations of body tilt and translation in darkness. Their ability to manually control their own orientation was also evaluated using a joystick with which they nulled out the perceived tilt while the sled and centrifuge were in motion. Preliminary results confirm that the magnitude of perceived tilt increased during static tilt in roll after space flight. A deterioration in the crewmember to control tilt using non-visual inertial cues was also observed post-flight. However, the use of a tactile prosthesis indicating the direction of down on the subject's trunk improved manual control performance both before and after space flight.

  5. A Horizontal Tilt Correction Method for Ship License Numbers Recognition

    Science.gov (United States)

    Liu, Baolong; Zhang, Sanyuan; Hong, Zhenjie; Ye, Xiuzi

    2018-02-01

    An automatic ship license numbers (SLNs) recognition system plays a significant role in intelligent waterway transportation systems since it can be used to identify ships by recognizing the characters in SLNs. Tilt occurs frequently in many SLNs because the monitors and the ships usually have great vertical or horizontal angles, which decreases the accuracy and robustness of a SLNs recognition system significantly. In this paper, we present a horizontal tilt correction method for SLNs. For an input tilt SLN image, the proposed method accomplishes the correction task through three main steps. First, a MSER-based characters’ center-points computation algorithm is designed to compute the accurate center-points of the characters contained in the input SLN image. Second, a L 1- L 2 distance-based straight line is fitted to the computed center-points using M-estimator algorithm. The tilt angle is estimated at this stage. Finally, based on the computed tilt angle, an affine transformation rotation is conducted to rotate and to correct the input SLN horizontally. At last, the proposed method is tested on 200 tilt SLN images, the proposed method is proved to be effective with a tilt correction rate of 80.5%.

  6. Photovoltaic Modules: Effect of Tilt Angle on Soiling

    Science.gov (United States)

    Cano, Jose

    2011-12-01

    Photovoltaic (PV) systems are one of the next generation's renewable energy sources for our world energy demand. PV modules are highly reliable. However, in polluted environments, over time, they will collect grime and dust. There are also limited field data studies about soiling losses on PV modules. The study showed how important it is to investigate the effect of tilt angle on soiling. The study includes two sets of mini-modules. Each set has 9 PV modules tilted at 0, 5, 10, 15, 20, 23, 30, 33 and 40°. The first set called "Cleaned" was cleaned every other day. The second set called "Soiled" was never cleaned after the first day. The short circuit current, a measure of irradiance, and module temperature was monitored and recorded every two minutes over three months (January-March 2011). The data were analyzed to investigate the effect of tilt angle on daily and monthly soiling, and hence transmitted solar insolation and energy production by PV modules. The study shows that during the period of January through March 2011 there was an average loss due to soiling of approximately 2.02% for 0° tilt angle. Modules at tilt angles 23° and 33° also have some insolation losses but do not come close to the module at 0° tilt angle. Tilt angle 23° has approximately 1.05% monthly insolation loss, and 33° tilt angle has an insolation loss of approximately 0.96%. The soiling effect is present at any tilt angle, but the magnitude is evident: the flatter the solar module is placed the more energy it will lose.

  7. Pulse Front Tilt and Laser Plasma Acceleration

    Science.gov (United States)

    Mittelberger, Daniel; Thévenet, Maxence; Nakamura, Kei; Lehe, Remi; Gonsalves, Anthony; Benedetti, Carlo; Leemans, Wim

    2017-10-01

    Pulse front tilt (PFT) is potentially present in any CPA laser system, but its effects may be overlooked because spatiotemporal pulse characterization is considerably more involved than measuring only spatial or temporal profile. PFT is particularly important for laser plasma accelerators (LPA) because it influences electron beam injection and steering. In this work, experimental results from the BELLA Center will be presented that demonstrate the effect of optical grating misalignment and optical compression, resulting in PFT, on accelerator performance. Theoretical models of laser and electron beam steering will be introduced based on particle-in-cell simulations showing distortion of the plasma wake. Theoretical predictions will be compared with experiments and complimentary simulations, and tolerances on PFT and optical compressor alignment will be developed as a function of LPA performance requirements. This work was supported by the Office of High Energy Physics, Office of Science, US Department of Energy under Contract DE-AC02-05CH11231 and the National Science Foundation under Grant PHY-1415596.

  8. Flow tilt angles near forest edges - Part 1: Sonic anemometry

    DEFF Research Database (Denmark)

    Dellwik, Ebba; Mann, Jakob; Larsen, Klaus Steenberg

    2010-01-01

    An analysis of flow tilt angles from a fetch-limited beech forest site with clearings is presented in the context of vertical advection of carbon dioxide. Flow angles and vertical velocities from two sonic anemometers by different manufacturers were analyzed. Instead of using rotations, where zero...... distortion and vertical alignment, it was only possible to a limited extent to relate sonic anemometer flow tilt angles to upwind forest edges, but the results by the lidar indicated that an internal boundary layer affect flow tilt angles at 21m above the forest. This is in accordance with earlier studies...

  9. Ocular tilt reaction due to a cerebellar hemorrhage.

    Science.gov (United States)

    Tsuda, Hiromasa; Tanaka, Kozue

    2014-01-01

    A 78-year-old man with essential hypertension abruptly developed complete ocular tilt reaction (OTR) which consisted of concomitant skew deviation with left hypertropia, extorsion of the right eye and intorsion of the left, and rightward head tilt. Cranial computed tomography demonstrated a localized cerebellar hemorrhage involving the left nodulus. The patient became asymptomatic within two weeks. This is a first reported case of complete OTR due to a cerebellar hemorrhage. Concomitant skew deviation is a common symptom of cerebellar lesions. Moreover, unilateral damage to the utricular pathway due to involvement of the left nodulus might cause rightward conjugate ocular torsion and rightward head tilt.

  10. The Effects of Using Microsoft Power Point on EFL Learners' Attitude and Anxiety: Case Study of Two Master Students of Didactics of English as a Foreign Language, Djillali Liabes University, Sidi Bel Abbes, Algeria

    Science.gov (United States)

    Benghalem, Boualem

    2015-01-01

    This study aims to investigate the effects of using ICT tools such as Microsoft PowerPoint on EFL students' attitude and anxiety. The participants in this study were 40 Master 2 students of Didactics of English as a Foreign Language, Djillali Liabes University, Sidi Bel Abbes Algeria. In order to find out the effects of Microsoft PowerPoint on EFL…

  11. The effects of lateral head tilt on ocular astigmatic axis

    Directory of Open Access Journals (Sweden)

    Hamid Fesharaki

    2014-01-01

    Conclusion: Any minimal angle of head tilt may cause erroneous measurement of astigmatic axis and should be avoided during refraction. One cannot rely on the compensatory function of ocular counter-torsion during the refraction.

  12. Tilt Rotor Aeroacoustic Model (TRAM): A New Rotorcraft Research Facility

    National Research Council Canada - National Science Library

    Young, Larry A

    1998-01-01

    ...". These two test stands are inclusively called the Tilt Rotor Aeroacoustic Model "TRAM". The baseline proprotors and airframe of the TRAM test stands are nominally 1/4-scale representations of the V-22 Osprey aircraft...

  13. A tilting approach to ranking influence

    KAUST Repository

    Genton, Marc G.

    2014-12-01

    We suggest a new approach, which is applicable for general statistics computed from random samples of univariate or vector-valued or functional data, to assessing the influence that individual data have on the value of a statistic, and to ranking the data in terms of that influence. Our method is based on, first, perturbing the value of the statistic by ‘tilting’, or reweighting, each data value, where the total amount of tilt is constrained to be the least possible, subject to achieving a given small perturbation of the statistic, and, then, taking the ranking of the influence of data values to be that which corresponds to ranking the changes in data weights. It is shown, both theoretically and numerically, that this ranking does not depend on the size of the perturbation, provided that the perturbation is sufficiently small. That simple result leads directly to an elegant geometric interpretation of the ranks; they are the ranks of the lengths of projections of the weights onto a ‘line’ determined by the first empirical principal component function in a generalized measure of covariance. To illustrate the generality of the method we introduce and explore it in the case of functional data, where (for example) it leads to generalized boxplots. The method has the advantage of providing an interpretable ranking that depends on the statistic under consideration. For example, the ranking of data, in terms of their influence on the value of a statistic, is different for a measure of location and for a measure of scale. This is as it should be; a ranking of data in terms of their influence should depend on the manner in which the data are used. Additionally, the ranking recognizes, rather than ignores, sign, and in particular can identify left- and right-hand ‘tails’ of the distribution of a random function or vector.

  14. Magnetic configurations of the tilted current sheets in magnetotail

    Directory of Open Access Journals (Sweden)

    C. Shen

    2008-11-01

    Full Text Available In this research, the geometrical structures of tilted current sheet and tail flapping waves have been analysed based on multiple spacecraft measurements and some features of the tilted current sheets have been made clear for the first time. The geometrical features of the tilted current sheet revealed in this investigation are as follows: (1 The magnetic field lines (MFLs in the tilted current sheet are generally plane curves and the osculating planes in which the MFLs lie are about vertical to the equatorial plane, while the normal of the tilted current sheet leans severely to the dawn or dusk side. (2 The tilted current sheet may become very thin, the half thickness of its neutral sheet is generally much less than the minimum radius of the curvature of the MFLs. (3 In the neutral sheet, the field-aligned current density becomes very large and has a maximum value at the center of the current sheet. (4 In some cases, the current density is a bifurcated one, and the two humps of the current density often superpose two peaks in the gradient of magnetic strength, indicating that the magnetic gradient drift current is possibly responsible for the formation of the two humps of the current density in some tilted current sheets. Tilted current sheets often appear along with tail current sheet flapping waves. It is found that, in the tail flapping current sheets, the minimum curvature radius of the MFLs in the current sheet is rather large with values around 1 RE, while the neutral sheet may be very thin, with its half thickness being several tenths of RE. During the flapping waves, the current sheet is tilted substantially, and the maximum tilt angle is generally larger than 45°. The phase velocities of these flapping waves are several tens km/s, while their periods and wavelengths are several tens of minutes, and several earth radii, respectively. These tail flapping events generally last several hours and occur during quiet periods or periods of

  15. Tilt Table Test: State of The Art

    Directory of Open Access Journals (Sweden)

    Gonzalo Barón-Esquivias

    2003-10-01

    Full Text Available The loss of consciousness has been a subject of wonder and uncertainty in humans, and for this reason it has been the object of medical investigation since the beginning of time. Even actually, it is certainly an unresolved clinical problem. Many centuries ago, complicated exorcisms and remedies were used on these unfortunate patients, who upon regaining consciousness would find themselves soaked in miraculous liquids, ingesting curative potions, and often on the way to be burned accused of being possessed. In the seventeen century, physicians began to relate loss of consciousness and haemodinamic changes. William Harvey was perhaps the first to describe a circulatory response (vasovagal reaction during a phlebotomy in the year 1628: “...Yet it fear or any other cause, or something do intervene through passion of the mind, so that the heart do beat more faintly, the blood will be no means pass through but drop after drop…”1. During the nineteenth century, loss of consciousness was the object of studies and research, and the vagally mediated cardioinhibition, as a primary cause, was noted by Foster who proposed that profound bradycardia diminished cerebral perfusion to a level inadequate to maintain consciousness2. At this time, it was reported the first use of the tilt-table test3. Commonly referred to as fainting or loss of consciousness, from last century the preferred medical term is syncope, which itself is derived from the Greek term “syncoptein” meaning “to cut short”. Syncope is defined as the sudden loss of consciousness and postural tone with spontaneous recovery. In 1907, Gowers was the first person to use the term vasovagal syncope4. In 1918 was published the work in which Cotton and Lewis described for the first time the clinical characteristics that are still used today to recognize the syncopal reaction5. However, it was not till 1932 when Lewis described this reaction as being characterized by a combination of bradycardia

  16. Influence of Vibrotactile Feedback on Controlling Tilt Motion After Spaceflight

    Science.gov (United States)

    Wood, S. J.; Rupert, A. H.; Vanya, R. D.; Esteves, J. T.; Clement, G.

    2011-01-01

    We hypothesize that adaptive changes in how inertial cues from the vestibular system are integrated with other sensory information leads to perceptual disturbances and impaired manual control following transitions between gravity environments. The primary goals of this ongoing post-flight investigation are to quantify decrements in manual control of tilt motion following short-duration spaceflight and to evaluate vibrotactile feedback of tilt as a sensorimotor countermeasure. METHODS. Data is currently being collected on 9 astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation (216 deg/s, body axis, thereby eliciting canal reflexes without concordant otolith or visual cues. A simple 4 tactor system was implemented to provide feedback when tilt position exceeded predetermined levels in either device. Closed-loop nulling tasks are performed during random tilt steps or sum-of-sines (TTS only) with and without vibrotactile feedback of chair position. RESULTS. On landing day the manual control performance without vibrotactile feedback was reduced by >30% based on the gain or the amount of tilt disturbance successfully nulled. Manual control performance tended to return to baseline levels within 1-2 days following landing. Root-mean-square position error and tilt velocity were significantly reduced with vibrotactile feedback. CONCLUSIONS. These preliminary results are consistent with our hypothesis that adaptive changes in vestibular processing corresponds to reduced manual control performance following G-transitions. A simple vibrotactile prosthesis improves the ability to null out tilt motion within a limited range of motion disturbances.

  17. Group theoretical analysis of octahedral tilting in perovskites

    International Nuclear Information System (INIS)

    Howard, C.J.; Stokes, H.T.

    1998-01-01

    Full text: Structures of the perovskite family, ABX 3 , have interested crystallographers over many years, and continue to attract attention on account of their fascinating electrical and magnetic properties, for example the giant magnetoresistive effects exhibited by certain perovskite materials. The ideal perovskite (cubic, space group Pm -/3 m) is a particularly simple structure, but also a demanding one, since aside from the lattice parameter there are no variable parameters in the structure. Consequently, the majority of perovskite structures are distorted perovskites (hettotypes), the most common distortion being the corner-linked tilting of the practically rigid BX 6 octahedral units. In this work, group theoretical methods have been applied to the study of octahedral tilting in perovskites. The only irreducible representations of the parent group (Pm -/3 m) which produce octahedral tilting subject to corner-linking constraints are M + / 3 and R 4 ' + . A six-dimensional order parameter in the reducible representation space of M + / 3 + R + / 4 describes the different possible tilting patterns. The space groups for the different perovskites are then simply the isotropy subgroups, comprising those operations which leave the order parameter invariant. The isotropy subgroups are obtained from a computer program or tabulations. The analysis yields a list of fifteen possible space groups for perovskites derived through octahedral tilting. A connection is made to the (twenty-three) tilt systems given previously by Glazer. The group-subgroup relationships have been derived and displayed. It is interesting to note that all known perovskites based on octahedral tilting conform with the fifteen space groups on our list, with the exception of one perovskite at high temperature, the structure of which seems poorly determined

  18. Retinal Nerve Fiber Layer Protrusion Associated with Tilted Optic Discs.

    Science.gov (United States)

    Chiang, Jaclyn; Yapp, Michael; Ly, Angelica; Hennessy, Michael P; Kalloniatis, Michael; Zangerl, Barbara

    2018-03-01

    This study resulted in the identification of an optic nerve head (ONH) feature associated with tilted optic discs, which might potentially contribute to ONH pathologies. Knowledge of such findings will enhance clinical insights and drive future opportunities to understand disease processes related to tilted optic discs. The aim of this study was to identify novel retinal nerve fiber layer (RNFL) anomalies by evaluating tilted optic discs using optical coherence tomography. An observed retinal nerve fiber protrusion was further investigated for association with other morphological or functional parameters. A retrospective review of 400 randomly selected adult patients with ONH examinations was conducted in a referral-only, diagnostic imaging center. After excluding other ONH pathologies, 215 patients were enrolled and evaluated for optic disc tilt and/or torsion. Gross anatomical ONH features, including size and rim or parapapillary region elevation, were assessed with stereoscopic fundus photography. Optical coherence tomography provided detailed morphological information of individual retinal layers. Statistical analysis was applied to identify significant changes between individual patient cohorts. A dome-shaped hyperreflective RNFL bulge, protruding into the neurosensory retina at the optic disc margins, was identified in 17 eyes with tilted optic discs. Available follow-up data were inconclusive regarding natural changes with this ONH feature. This RNFL herniation was significantly correlated with smaller than average optic disc size (P = .005), congenital disc tilt (P optic discs, which has not previously been assessed as an independent ONH structure. The feature is predominantly related to congenital crowded, small optic discs and variable between patients. This study is an important first step to elucidate diagnostic capabilities of tilted disc morphological changes and understanding associated functional deficits.

  19. Recording Tilt with Broadband Seismic Sensors at Erupting Volcanoes

    Science.gov (United States)

    Young, B. E.; Lees, J. M.; Lyons, J. J.

    2011-12-01

    The horizontal components of broadband seismometers are known to be susceptible to gravitational acceleration due to slow tilting, and this has been successfully exploited to assess ground deformation at many volcanoes, including Anatahan (Mariana Islands), Meakan-dake (Japan), Santiaguito (Guatemala) and Stromboli (Italy). Tilt can be estimated from seismic velocity by differentiating, scaling to remove gravity, and applying an instrument correction. The fundamental assumption in estimating tilt from broadband data is that the signal recorded is the result of tilt and not translation, thus analysis of tilt require filtering below corner frequencies of seismic instruments, where the response to tilt should be flat. However, processing techniques for deriving tilt are not uniform among researchers. Filter type and passband allowance for the processing of data sets differs from case to case, and the dominant periods of tilt signals may vary from tens to hundreds of seconds. For instance, data from Santiaguito was filtered in the 600-30s passband, while at Anatahan filters spanned 13 hours to 8 minutes. In our study, we investigate tilt from seismic data sets at Karymsky (Kamchatka, Russia), Fuego (Guatemala), Yasur (Vanuatu), and Tungurahua (Ecuador) to understand implementation and limitations of this tool. We examine the importance of filter-type distortion related to filtering on the seismic signal. For example, a comparison of time domain versus frequency domain implementation is explored using a variety of lowpass and bandpass filters. We also investigate the advantages and drawbacks of causal versus acausal filters. In a few cases tiltmeters have been co-located with broadband seismic sensors for direct comparison. Signals at Mt. St. Helens, Stromboli, Sakurajima, and Semeru show a correlation of tilt and seismic records, although records at Karymsky volcano suggest that no tilt is recorded on either instrument. We speculate that strong vent explosions exhibit

  20. Rotating Shaft Tilt Angle Measurement Using an Inclinometer

    Science.gov (United States)

    Luo, Jun; Wang, Zhiqian; Shen, Chengwu; Wen, Zhuoman; Liu, Shaojin; Cai, Sheng; Li, Jianrong

    2015-10-01

    This paper describes a novel measurement method to accurately measure the rotating shaft tilt angle of rotating machine for alignment or compensation using a dual-axis inclinometer. A model of the rotating shaft tilt angle measurement is established using a dual-axis inclinometer based on the designed mechanical structure, and the calculation equation between the rotating shaft tilt angle and the inclinometer axes outputs is derived under the condition that the inclinometer axes are perpendicular to the rotating shaft. The reversal measurement method is applied to decrease the effect of inclinometer drifts caused by temperature, to eliminate inclinometer and rotating shaft mechanical error and inclinometer systematic error to attain high measurement accuracy. The uncertainty estimation shows that the accuracy of rotating shaft tilt angle measurement depends mainly on the inclinometer uncertainty and its uncertainty is almost the same as the inclinometer uncertainty in the simulation. The experimental results indicate that measurement time is 4 seconds; the range of rotating shaft tilt angle is 0.002° and its standard deviation is 0.0006° using NS-5/P2 inclinometer, whose precision and resolution are ±0.01° and 0.0005°, respectively.

  1. Rotating Shaft Tilt Angle Measurement Using an Inclinometer

    Directory of Open Access Journals (Sweden)

    Luo Jun

    2015-10-01

    Full Text Available This paper describes a novel measurement method to accurately measure the rotating shaft tilt angle of rotating machine for alignment or compensation using a dual-axis inclinometer. A model of the rotating shaft tilt angle measurement is established using a dual-axis inclinometer based on the designed mechanical structure, and the calculation equation between the rotating shaft tilt angle and the inclinometer axes outputs is derived under the condition that the inclinometer axes are perpendicular to the rotating shaft. The reversal measurement method is applied to decrease the effect of inclinometer drifts caused by temperature, to eliminate inclinometer and rotating shaft mechanical error and inclinometer systematic error to attain high measurement accuracy. The uncertainty estimation shows that the accuracy of rotating shaft tilt angle measurement depends mainly on the inclinometer uncertainty and its uncertainty is almost the same as the inclinometer uncertainty in the simulation. The experimental results indicate that measurement time is 4 seconds; the range of rotating shaft tilt angle is 0.002° and its standard deviation is 0.0006° using NS-5/P2 inclinometer, whose precision and resolution are ±0.01° and 0.0005°, respectively.

  2. New tilted-poles Wien filter with enhanced performance

    Science.gov (United States)

    Leal-Quiros, E.; Prelas, M. A.

    1989-03-01

    The Wien filter is an E×B deflecting analyzer with the electrostatic field perpendicular to the magnetostatic field. The twofold functions of the Wien filter are as an energy analyzer as well as a mass analyzer. It has very high resolution for paraxial charged-particle beams with V=E/B, the Wien velocity. Two Wien filters, a tilted-poles Wien filter, and a classical parallel-rectangular-poles Wien filter were built and tested for electrons up to 3.5 keV and protons beams of 200 eV. (The tilted-poles Wien filter is a new diagnostic developed by the authors.) The performance of the two is compared, and the tilted-poles Wien filter has superior resolution to the classical Wien filter. Both Wien filters appear to have features useful for high-temperature plasma diagnostics, including simultaneous measurement of energy and mass spectra, and high resolution.

  3. New tilted-poles Wien filter with enhanced performance

    Energy Technology Data Exchange (ETDEWEB)

    Leal-Quiros, E.; Prelas, M.A.

    1989-03-01

    The Wien filter is an E x B deflecting analyzer with the electrostatic field perpendicular to the magnetostatic field. The twofold functions of the Wien filter are as an energy analyzer as well as a mass analyzer. It has very high resolution for paraxial charged-particle beams with V = E/B, the Wien velocity. Two Wien filters, a tilted-poles Wien filter, and a classical parallel-rectangular-poles Wien filter were built and tested for electrons up to 3.5 keV and protons beams of 200 eV. (The tilted-poles Wien filter is a new diagnostic developed by the authors.) The performance of the two is compared, and the tilted-poles Wien filter has superior resolution to the classical Wien filter. Both Wien filters appear to have features useful for high-temperature plasma diagnostics, including simultaneous measurement of energy and mass spectra, and high resolution.

  4. Quantum well electronic states in a tilted magnetic field.

    Science.gov (United States)

    Trallero-Giner, C; Padilha, J X; Lopez-Richard, V; Marques, G E; Castelano, L K

    2017-08-16

    We report the energy spectrum and the eigenstates of conduction and uncoupled valence bands of a quantum well under the influence of a tilted magnetic field. In the framework of the envelope approximation, we implement two analytical approaches to obtain the nontrivial solutions of the tilted magnetic field: (a) the Bubnov-Galerkin spectral method and b) the perturbation theory. We discuss the validity of each method for a broad range of magnetic field intensity and orientation as well as quantum well thickness. By estimating the accuracy of the perturbation method, we provide explicit analytical solutions for quantum wells in a tilted magnetic field configuration that can be employed to study several quantitative phenomena.

  5. Method to fabricate a tilted logpile photonic crystal

    Science.gov (United States)

    Williams, John D.; Sweatt, William C.

    2010-10-26

    A method to fabricate a tilted logpile photonic crystal requires only two lithographic exposures and does not require mask repositioning between exposures. The mask and photoresist-coated substrate are spaced a fixed and constant distance apart using a spacer and the stack is clamped together. The stack is then tilted at a crystallographic symmetry angle (e.g., 45 degrees) relative to the X-ray beam and rotated about the surface normal until the mask is aligned with the X-ray beam. The stack is then rotated in plane by a small stitching angle and exposed to the X-ray beam to pattern the first half of the structure. The stack is then rotated by 180.degree. about the normal and a second exposure patterns the remaining half of the structure. The method can use commercially available DXRL scanner technology and LIGA processes to fabricate large-area, high-quality tilted logpile photonic crystals.

  6. Flow tilt angles near forest edges - Part 2: Lidar anemometry

    DEFF Research Database (Denmark)

    Dellwik, Ebba; Mann, Jakob; Bingöl, Ferhat

    2010-01-01

    A novel way of estimating near-surface mean flow tilt angles from ground based Doppler lidar measurements is presented. The results are compared with traditional mast based in-situ sonic anemometry. The tilt angle assessed with the lidar is based on 10 or 30 min mean values of the velocity field......) a fetch-limited beech forest site taken at 48–175 m a.g.l. (above ground level), (2) a reference site in flat agricultural terrain and (3) a second reference site in complex terrain are presented. The method to derive flow tilt angles and mean vertical velocities from lidar has several advantages compared...... alignment error at a multitude of heights. Disadvantages with estimating vertical velocities from a lidar compared to mast-based measurements are potentially slightly increased levels of statistical errors due to limited sampling time, because the sampling is disjunct, and a requirement for homogeneous flow...

  7. Ground tilt monitoring at Phlegraean Fields (Italy: a methodological approach

    Directory of Open Access Journals (Sweden)

    C. Del Gaudio

    2003-06-01

    Full Text Available Among geodetic methods used for monitoring ground deformation in volcanic areas, tiltmetry represents the most rapid technique and therefore it is used by almost all the volcanological observatories in the world. The deformation of volcanic building is not only the result of endogenous causes (i.e. dykes injection or magma rising, but also non-tectonic environmental factors. Such troubles cannot be removed completely but they can be reduce. This article outlines the main source of errors affecting the signals recorded by Phlegraean tilt, network, such as the dependence of the tilt response on temperature and to the thermoelastic effect on ground deformation. The analytical procedure used to evaluate about such errors and their reduction is explained. An application to data acquired from the tilt network during two distinct phases of ground uplift and subsidence of the Phlegraean Fields is reported.

  8. Coulomb interaction effect in tilted Weyl fermion in two dimensions

    Science.gov (United States)

    Isobe, Hiroki; Nagaosa, Naoto

    Weyl fermions with tilted linear dispersions characterized by several different velocities appear in some systems including the quasi-two-dimensional organic semiconductor α-(BEDT-TTF)2I3 and three-dimensional WTe2. The Coulomb interaction between electrons modifies the velocities in an essential way in the low energy limit, where the logarithmic corrections dominate. Taking into account the coupling to both the transverse and longitudinal electromagnetic fields, we derive the renormalization group equations for the velocities of the tilted Weyl fermions in two dimensions, and found that they increase as the energy decreases and eventually hit the velocity of light c to result in the Cherenkov radiation. Especially, the system restores the isotropic Weyl cone even when the bare Weyl cone is strongly tilted and the velocity of electrons becomes negative in certain directions.

  9. Absolute Measurement of Tilts via Fourier Analysis of Interferograms

    Science.gov (United States)

    Toland, Ronald W.

    2004-01-01

    The Fourier method of interferogram analysis requires the introduction of a constant tilt into the interferogram to serve as a carrier signal for information on the figure of the surface under test. This tilt is usually removed in the first steps of analysis and ignored thereafter. However, in the problem of aligning optical components and systems, knowledge of part orientation is crucial to proper instrument performance. This paper outlines an algorithm which uses the normally ignored carrier signal in Fourier analysis to compute an absolute tilt (orientation) of the test surface. We also provide a brief outline of how this technique, incorporated in a rotating Twyman-Green interferometer, can be used in alignment and metrology of optical systems.

  10. The semiology of tilt-induced psychogenic pseudosyncope.

    Science.gov (United States)

    Tannemaat, Martijn R; van Niekerk, Julius; Reijntjes, Robert H; Thijs, Roland D; Sutton, Richard; van Dijk, J Gert

    2013-08-20

    To provide a detailed semiology to aid the clinical recognition of psychogenic pseudosyncope (PPS), which concerns episodes of apparent transient loss of consciousness (TLOC) that mimic syncope. We analyzed all consecutive tilt-table tests from 2006 to 2012 showing proven PPS, i.e., apparent TLOC had occurred without EEG changes or a decrease in heart rate (HR) or blood pressure (BP). We analyzed baseline characteristics, video data, EEG, ECG, and continuous BP measurements on a 1-second time scale. Data were compared with those of 69 cases of tilt-induced vasovagal syncope (VVS). Of 800 tilt-table tests, 43 (5.4%) resulted in PPS. The majority (74%) were women. The median duration of apparent TLOC was longer in PPS (44 seconds) than in VVS (20 seconds, p semiology of PPS as a clinical entity is vital to ensure accurate diagnosis.

  11. Tilt Precursors before Earthquakes on the San Andreas Fault, California.

    Science.gov (United States)

    Johnston, M J; Mortensen, C E

    1974-12-13

    An array of 14 biaxial shallow-borehole tiltmeters (at 1O(-7) radian sensitivity) has been installed along 85 kilometers of the San Andreas fault during the past year. Earthquake-related changes in tilt have been simultaneously observed on up to four independent instruments. At earthquake distances greater than 10 earthquake source dimensions, there are few clear indications of tilt change. For the four instruments with the longest records (> 10 months), 26 earthquakes have occurred since July 1973 with at least one instrument closer than 10 source dimensions and 8 earthquakes with more than one instrument within that distance. Precursors in tilt direction have been observed before more than 10 earthquakes or groups of earthquakes, and no similar effect has yet been seen without the occurrence of an earthquake.

  12. Robust tilt and lock mechanism for hopping actuator

    Energy Technology Data Exchange (ETDEWEB)

    Salton, Jonathan R.; Buerger, Stephen; Dullea, Kevin J.; Marron, Lisa C.; Salisbury, Curt Michael; Spletzer, Barry Louis

    2017-02-07

    A tilt and lock apparatus that includes a tilt servomechanism, a spiral torsion spring, a lock wheel, and a lock hook is described herein. The spiral torsion spring is mechanically coupled to the tilt servomechanism and the lock wheel (which includes an opening). When a shaft is positioned through the opening, rotation of the lock wheel is in unison with rotation of the shaft. An external surface of the lock wheel includes one or more grooves. The lock hook includes a head that engages and disengages the grooves. The lock wheel is stationary when the head engages one of the grooves and is rotatable when the head disengages the grooves. The head and the grooves are geometrically aligned when engaged to prevent creation of a force that acts to disengage the head responsive to an applied force acting on the shaft.

  13. Reverse time migration in tilted transversely isotropic media

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Linbing; Rector III, James W.; Hoversten, G. Michael

    2004-07-01

    This paper presents a reverse time migration (RTM) method for the migration of shot records in tilted transversely isotropic (TTI) media. It is based on the tilted TI acoustic wave equation that was derived from the dispersion relation. The RTM is a full depth migration allowing for velocity to vary laterally as well as vertically and has no dip limitations. The wave equation is solved by a tenth-order finite difference scheme. Using 2D numerical models, we demonstrate that ignoring the tilt angle will introduce both lateral and vertical shifts in imaging. The shifts can be larger than 0.5 wavelength in the vertical direction and 1.5 wavelength in the lateral direction.

  14. Tilted dipole model for bias-dependent photoluminescence pattern

    Science.gov (United States)

    Fujieda, Ichiro; Suzuki, Daisuke; Masuda, Taishi

    2014-12-01

    In a guest-host system containing elongated dyes and a nematic liquid crystal, both molecules are aligned to each other. An external bias tilts these molecules and the radiation pattern of the system is altered. A model is proposed to describe this bias-dependent photoluminescence patterns. It divides the liquid crystal/dye layer into sub-layers that contain electric dipoles with specific tilt angles. Each sub-layer emits linearly polarized light. Its radiation pattern is toroidal and is determined by the tilt angle. Its intensity is assumed to be proportional to the power of excitation light absorbed by the sub-layer. This is calculated by the Lambert-Beer's Law. The absorption coefficient is assumed to be proportional to the cross-section of the tilted dipole moment, in analogy to the ellipsoid of refractive index, to evaluate the cross-section for each polarized component of the excitation light. Contributions from all the sub-layers are added to give a final expression for the radiation pattern. Self-absorption is neglected. The model is simplified by reducing the number of sub-layers. Analytical expressions are derived for a simple case that consists of a single layer with tilted dipoles sandwiched by two layers with horizontally-aligned dipoles. All the parameters except for the tilt angle can be determined by measuring transmittance of the excitation light. The model roughly reproduces the bias-dependent photoluminescence patterns of a cell containing 0.5 wt. % coumarin 6. It breaks down at large emission angles. Measured spectral changes suggest that the discrepancy is due to self-absorption and re-emission.

  15. Tilted dipole model for bias-dependent photoluminescence pattern

    International Nuclear Information System (INIS)

    Fujieda, Ichiro; Suzuki, Daisuke; Masuda, Taishi

    2014-01-01

    In a guest-host system containing elongated dyes and a nematic liquid crystal, both molecules are aligned to each other. An external bias tilts these molecules and the radiation pattern of the system is altered. A model is proposed to describe this bias-dependent photoluminescence patterns. It divides the liquid crystal/dye layer into sub-layers that contain electric dipoles with specific tilt angles. Each sub-layer emits linearly polarized light. Its radiation pattern is toroidal and is determined by the tilt angle. Its intensity is assumed to be proportional to the power of excitation light absorbed by the sub-layer. This is calculated by the Lambert-Beer's Law. The absorption coefficient is assumed to be proportional to the cross-section of the tilted dipole moment, in analogy to the ellipsoid of refractive index, to evaluate the cross-section for each polarized component of the excitation light. Contributions from all the sub-layers are added to give a final expression for the radiation pattern. Self-absorption is neglected. The model is simplified by reducing the number of sub-layers. Analytical expressions are derived for a simple case that consists of a single layer with tilted dipoles sandwiched by two layers with horizontally-aligned dipoles. All the parameters except for the tilt angle can be determined by measuring transmittance of the excitation light. The model roughly reproduces the bias-dependent photoluminescence patterns of a cell containing 0.5 wt. % coumarin 6. It breaks down at large emission angles. Measured spectral changes suggest that the discrepancy is due to self-absorption and re-emission

  16. Stability of multi orifice active tilting-pad journal bearings

    DEFF Research Database (Denmark)

    Haugaard, Asger M.; Santos, Ilmar

    2010-01-01

    The stability properties of actively lubricated tilting-pad journal bearings are investigated theoretically. The bearing preload factor and control system gains are varied, and stable and unstable regions are identified. It is seen, that the control system influences bearing stability, and that t......The stability properties of actively lubricated tilting-pad journal bearings are investigated theoretically. The bearing preload factor and control system gains are varied, and stable and unstable regions are identified. It is seen, that the control system influences bearing stability...

  17. Tilt table standing for reducing spasticity after spinal cord injury.

    Science.gov (United States)

    Bohannon, R W

    1993-10-01

    A patient with a T12 spinal cord injury and intractable extensor spasms of the lower extremities participated in tilt table standing trial on 5 nonconsecutive days to determine if the intervention would affect his spasticity and spasms. Each day's standing trial was followed by an immediate reduction in lower extremity spasticity (measured using the modified Ashworth scale and pendulum testing). Standing was also accompanied by a reduction in spasms that lasted until the following morning. The reduction of spasms was particularly advantageous to the performance of car transfers. Tilt table standing merits further examination as a physical treatment of spasms that accompany central nervous system lesions.

  18. Sedimentary basins reconnaissance using the magnetic Tilt-Depth method

    Science.gov (United States)

    Salem, A.; Williams, S.; Samson, E.; Fairhead, D.; Ravat, D.; Blakely, R.J.

    2010-01-01

    We compute the depth to the top of magnetic basement using the Tilt-Depth method from the best available magnetic anomaly grids covering the continental USA and Australia. For the USA, the Tilt-Depth estimates were compared with sediment thicknesses based on drilling data and show a correlation of 0.86 between the datasets. If random data were used then the correlation value goes to virtually zero. There is little to no lateral offset of the depth of basinal features although there is a tendency for the Tilt-Depth results to be slightly shallower than the drill depths. We also applied the Tilt-Depth method to a local-scale, relatively high-resolution aeromagnetic survey over the Olympic Peninsula of Washington State. The Tilt-Depth method successfully identified a variety of important tectonic elements known from geological mapping. Of particular interest, the Tilt-Depth method illuminated deep (3km) contacts within the non-magnetic sedimentary core of the Olympic Mountains, where magnetic anomalies are subdued and low in amplitude. For Australia, the Tilt-Depth estimates also give a good correlation with known areas of shallow basement and sedimentary basins. Our estimates of basement depth are not restricted to regional analysis but work equally well at the micro scale (basin scale) with depth estimates agreeing well with drill hole and seismic data. We focus on the eastern Officer Basin as an example of basin scale studies and find a good level of agreement between previously-derived basin models. However, our study potentially reveals depocentres not previously mapped due to the sparse distribution of well data. This example thus shows the potential additional advantage of the method in geological interpretation. The success of this study suggests that the Tilt-Depth method is useful in estimating the depth to crystalline basement when appropriate quality aeromagnetic anomaly data are used (i.e. line spacing on the order of or less than the expected depth to

  19. Contribution to the study and characterization of three populations of nigella (Nigella sativa) in the semi-arid zone of the North-Western Algeria (W. Sidi Bel-Abbes)

    OpenAIRE

    Fatima SAHRAOUI; Mostefa HADDAD; Mimoune HAMOU

    2017-01-01

    Nigella sativa is an annual plant belonging to the family of Ranunculaceae. It is cultivated worldwide for its therapeutic use and culinary purposes. Three populations of black cumin (Nigella II, Nigella 2 and Nigella station) were the subject of a morphological characterization and adaptive to semi-arid conditions of the research site of the Algerian National Institute Agronomic Research institute (NIARA) of the region of Lamtar (Wilaya of Sidi Bel Abbes). The qualitative morphological c...

  20. Final Report-Confirmatory Survey Results for the ABB Combustion Engineering Site, Windsor, Connecticut; Revision 1 (DCN 5158-SR-02-1) (Docket No. 030-03754; RFTA No. 12-003)

    Energy Technology Data Exchange (ETDEWEB)

    ADAMS, WADE C

    2013-01-28

    The objectives of the confirmatory activities were to provide independent contractor field data reviews and to generate independent radiological data for use by the NRC in evaluating the adequacy and accuracy of the contractor's procedures and FSS results. ORAU reviewed ABB CE's decommissioning plan, final status survey plan, and the applicable soil DCGLs, which were developed based on an NRC-approved radiation dose assessment. The surveys included gamma surface scans, gamma direct measurements, and soil sampling.

  1. Downward continuation and tilt derivative of magnetic data for ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 126; Issue 4. Downward continuation and tilt derivative of magnetic data for delineation of concealed coal fire in East Basuria Colliery, Jharia coal field, India. S K Pal Jitendra Vaish Sahadev Kumar Piyush Priyam Abhay Kumar Bharti Rajwardhan Kumar. Volume ...

  2. Downward continuation and tilt derivative of magnetic data for ...

    Indian Academy of Sciences (India)

    S K Pal

    2017-06-12

    Jun 12, 2017 ... are corroborated with multi-seam occurrences, mine working levels and surface manifestation which are also correlated well with 3D model of downward continued anomaly distribution. Keywords. Downward continuation; tilt derivative; magnetic data; coal fire mapping; Jharia coal field;. India. 1.

  3. Development of tilted fibre Bragg gratings using highly coherent 255 ...

    Indian Academy of Sciences (India)

    E-mail: oprakash@rrcat.gov.in. DOI: 10.1007/s12043-013-0672-7; ePublication: 6 February 2014. Abstract. This paper reports the study on development of tilted fibre Bragg gratings using highly coherent 255 nm radiation, obtained from the second harmonic generation (SHG) of copper vapour laser (CVL). The transmission ...

  4. Modelling and Simulations of a Narrow Track Tilting Vehicle

    Directory of Open Access Journals (Sweden)

    JJ Chong

    2016-10-01

    Full Text Available Narrow track tilting vehicle is a new category of vehicle that combines the dynamical abilities of a passenger car with a motorcycle. In the presence of overturning moments during cornering, an accurate assessment of the lateral dynamics plays an important role to improve their stability and handling. In order to stabilise or control the narrow tilting vehicle, the demand tilt angle can be calculated from the vehicle’s lateral acceleration and controlled by either steering input of the vehicle or using additional titling actuator to reach this desired angle. The aim of this article is to present a new approach for developing the lateral dynamics model of a narrow track tilting vehicle. First, this approach utilises the well-known geometry ‘bicycle model’ and parameter estimation methods. Second, by using a tuning method, the unknown and uncertainties are taken into account and regulated through an optimisation procedure to minimise the model biases in order to improve the modelling accuracy. Therefore, the optimised model can be used as a platform to develop the vehicle control strategy. Numerical simulations have been performed in a comparison with the experimental data to validate the model accuracy.

  5. Analysis of a ferrofluid core differential transformer tilt measurement sensor

    Energy Technology Data Exchange (ETDEWEB)

    Medvegy, T.; Molnár, Á.; Molnár, G.; Gugolya, Z.

    2017-04-15

    In our work, we developed a ferrofluid core differential transformer sensor, which can be used to measure tilt and acceleration. The proposed sensor consisted of three coils, from which the primary was excited with an alternating current. In the space surrounded by the coils was a cell half-filled with ferrofluid, therefore in the horizontal state of the sensor the fluid distributes equally in the three sections of the cell surrounded by the three coils. Nevertheless when the cell is being tilted or accelerated (in the direction of the axis of the coils), there is a different amount of ferrofluid in the three sections. The voltage induced in the secondary coils strongly depends on the amount of ferrofluid found in the core surrounded by them, so the tilt or the acceleration of the cell becomes measurable. We constructed the sensor in several layouts. The linearly coiled sensor had an excellent resolution. Another version with a toroidal cell had almost perfect linearity and a virtually infinite measuring range. - Highlights: • A ferrofluid core differential transformer can be used to measure tilt. • The theoretical description of two different type of the sensor is introduced. • The measuring range, and the sensitivity depends on the dimensions of the sensor.

  6. Tilt Train Technology : A State of the Art Survey

    Science.gov (United States)

    1992-05-01

    This report presents an overview of the state-of-the-art in tilt-train technology. It is intended to give the reader a better understanding of the unique features of this approach to train design and the variations that exist. Briefly described is th...

  7. Manipulation of enhanced absorption with tilted hexagonal boron nitride slabs

    Science.gov (United States)

    Wu, Xiaohu; Fu, Ceji

    2018-04-01

    The wavevector of electromagnetic wave propagation in a hexagonal boron nitride (hBN) slab can be controlled by tilting its optical axis. This property can be used to manipulate the absorption in a hBN slab. By carefully analyzing the dependence of the absorptivity of a thin hBN slab on the tilted angle of its optical axis, we propose a structure that can realize great absorptivity enhancement in a band by stacking hBN slabs of different tilted angles. Our numerical results show that the absorptivity of a structure made of 91 stacked hBN slabs can be achieved higher than 0.94 in the wavenumber range from 1367 to 1580 cm-1 when the tilted angles of the slabs are properly arranged. The strong absorption is attributed to the combination of impedance matching at the slab interfaces and enlarged wavevectors in the slabs. This work reveals a novel way to realize strong absorption with anisotropic materials for applications in areas such as thermal radiative energy harvesting and conversion.

  8. Dynamic tilt illusion induced by continuous contextual orientation alternations.

    Science.gov (United States)

    Yuan, Xiangyong; Zhang, Xilei; Jiang, Yi

    2017-11-01

    In the classic tilt illusion, the perceived orientation of a center patch is shifted away from its oriented context. Additionally, a stronger illusion effect is yielded when the center patch is simultaneously rather than asynchronously presented with a constant context for a shorter duration. However, little is known about the temporal characteristic of the tilt illusion in a reverse situation in which a constant center patch is presented throughout while the contexts change. Therefore, we continuously alternated two opposite-oriented contexts and manipulated alternate speeds to examine how the tilt illusion would build up as a function of dynamic contextual alternation. Our results revealed that dynamic alternations between leftward- and rightward-oriented contexts caused a static vertical grating at the center to apparently sway from side to side. More importantly, the apparent sway illusion was modulated by the alternate speed of the oriented contexts (up to 8-10 Hz); the quicker the alternation is, the faster and weaker the apparent sway is. Intriguingly, the temporal characteristic of the "dynamic tilt illusion" suggests that, under a varying environment, the suppressions from temporally adjacent surrounds would be chunked into discrete epochs before affecting our percept.

  9. Tilted hexagonal post arrays: DNA electrophoresis in anisotropic media

    Science.gov (United States)

    Chen, Zhen; Dorfman, Kevin D.

    2013-01-01

    Using Brownian dynamics simulations, we show that DNA electrophoresis in a hexagonal array of micron-sized posts changes qualitatively when the applied electric field vector is not coincident with the lattice vectors of the array. DNA electrophoresis in such “tilted” post arrays is superior to the standard “un-tilted” approach; while the time required to achieve a resolution of unity in a tilted post array is similar to an un-tilted array at a low electric field strengths, this time (i) decreases exponentially with electric field strength in a tilted array and (ii) increases exponentially with electric field strength in an un-tilted array. Although the DNA dynamics in a post array are complicated, the electrophoretic mobility results indicate that the “free path”, i.e., the average distance of ballistic trajectories of point sized particles launched from random positions in the unit cell until they intersect the next post, is a useful proxy for the detailed DNA trajectories. The analysis of the free path reveals a fundamental connection between anisotropy of the medium and DNA transport therein that goes beyond simply improving the separation device. PMID:23868490

  10. Modelling of LEG tilting pad journal bearings with active lubrication

    DEFF Research Database (Denmark)

    Cerda Varela, Alejandro Javier; García, Asier Bengoechea; Santos, Ilmar

    2017-01-01

    This work constitutes the first step in a research effort aimed at studying the feasibility of introducing an active lubrication concept in tilting pad journal bearings (TPJBs) that feature the leading edge groove (LEG) lubrication system. The modification of the oil flow into each pad supply gro...

  11. Cellular structures using U_q-tilting modules

    DEFF Research Database (Denmark)

    Andersen, Henning Haahr; Stroppel, Catharina; Tubbenhauer, Daniel

    We use the theory of Uq-tilting modules to construct cellular bases for centralizer algebras. Our methods are quite general and work for any quantum group Uq attached to a Cartan matrix and include the non semi-simple cases for q being a root of unity and ground fields of positive characteristic...

  12. Simulations of Micropumps Based on Tilted Flexible Fibers

    Science.gov (United States)

    Hancock, Matthew; Elabbasi, Nagi; Demirel, Melik

    2015-11-01

    Pumping liquids at low Reynolds numbers is challenging because of the principle of reversibility. We report here a class of microfluidic pump designs based on tilted flexible structures that combines the concepts of cilia (flexible elastic elements) and rectifiers (e.g., Tesla valves, check valves). We demonstrate proof-of-concept with 2D and 3D fluid-structure interaction (FSI) simulations in COMSOL Multiphysics®of micropumps consisting of a source for oscillatory fluidic motion, e.g. a piston, and a channel lined with tilted flexible rods or sheets to provide rectification. When flow is against the rod tilt direction, the rods bend backward, narrowing the channel and increasing flow resistance; when flow is in the direction of rod tilt, the rods bend forward, widening the channel and decreasing flow resistance. The 2D and 3D simulations involve moving meshes whose quality is maintained by prescribing the mesh displacement on guide surfaces positioned on either side of each flexible structure. The prescribed displacement depends on structure bending and maintains mesh quality even for large deformations. Simulations demonstrate effective pumping even at Reynolds numbers as low as 0.001. Because rod rigidity may be specified independently of Reynolds number, in principle, rod rigidity may be reduced to enable pumping at arbitrarily low Reynolds numbers.

  13. Abnormal Tilt Perception During Centrifugation in Patients with Vestibular Migraine.

    Science.gov (United States)

    Wang, Joanne; Lewis, Richard F

    2016-06-01

    Vestibular migraine (VM), defined as vestibular symptoms caused by migraine mechanisms, is very common but poorly understood. Because dizziness is often provoked in VM patients when the semicircular canals and otolith organs are stimulated concurrently (e.g., tilting the head relative to gravity), we measured tilt perception and eye movements in patients with VM and in migraine and normal control subjects during fixed-radius centrifugation, a paradigm that simultaneously modulates afferent signals from the semicircular canals and otoliths organs. Twenty-four patients (8 in each category) were tested with a motion paradigm that generated an inter-aural centrifugal force of 0.36 G, resulting in a 20° tilt of the gravito-inertial force in the roll plane. We found that percepts of roll tilt developed slower in VM patients than in the two control groups, but that eye movement responses, including the shift in the eye's rotational axis, were equivalent in all three groups. These results demonstrate a change in vestibular perception in VM that is unaccompanied by changes in vestibular-mediated eye movements and suggest that either the brain's integration of canal and otolith signals or the dynamics of otolith responses are aberrant in patients with VM.

  14. The impact of gravity during head-up tilt

    DEFF Research Database (Denmark)

    Ottesen, Johnny T.; Olufsen, Mette; Smith, Brittany

    The impact of gravity during head-up tilt, a test often used in the clinic to diagnose patients who suffer from dizziness or frequent episodes of syncope, is not well described. This study uses mathematical modeling to analyze experimental blood pressure data measured at the level of the aorta...

  15. Impaired perception of surface tilt in progressive supranuclear palsy.

    Directory of Open Access Journals (Sweden)

    Marian L Dale

    Full Text Available Progressive supranuclear palsy (PSP is characterized by early postural instability and backward falls. The mechanisms underlying backward postural instability in PSP are not understood. The aim of this study was to test the hypothesis that postural instability in PSP is a result of dysfunction in the perception of postural verticality.We gathered posturography data on 12 subjects with PSP to compare with 12 subjects with idiopathic Parkinson's Disease (PD and 12 healthy subjects. Objective tests of postural impairment included: dynamic sensory perception tests of gravity and of surface oscillations, postural responses to surface perturbations, the sensory organization test of postural sway under altered sensory conditions and limits of stability in stance.Perception of toes up (but not toes down surface tilt was reduced in subjects with PSP compared to both control subjects (p≤0.001 standing, p≤0.007 seated and subjects with PD (p≤0.03 standing, p≤0.04 seated. Subjects with PSP, PD and normal controls accurately perceived the direction of gravity when standing on a tilting surface. Unlike PD and control subjects, subjects with PSP exerted less postural corrective torque in response to toes up surface tilts.Difficulty perceiving backward tilt of the surface or body may account for backward falls and postural impairments in patients with PSP. These observations suggest that abnormal central integration of sensory inputs for perception of body and surface orientation contributes to the pathophysiology of postural instability in PSP.

  16. determination of determination of optimal tilt angle for maximum

    African Journals Online (AJOL)

    eobe

    The analysis showed that the best tilt angle for PV energy production is 60 if the module is fixed module ... suitable solar technology at an efficiency of 1%. Also, ... it. Thus, achieving the maximum possible performance is critical in PV power generation [14]. Installing PV modules on either a single or dual-axis trackers is one.

  17. Novel tilt-curvature coupling in lipid membranes

    Science.gov (United States)

    Terzi, M. Mert; Deserno, Markus

    2017-08-01

    On mesoscopic scales, lipid membranes are well described by continuum theories whose main ingredients are the curvature of a membrane's reference surface and the tilt of its lipid constituents. In particular, Hamm and Kozlov [Eur. Phys. J. E 3, 323 (2000)] have shown how to systematically derive such a tilt-curvature Hamiltonian based on the elementary assumption of a thin fluid elastic sheet experiencing internal lateral pre-stress. Performing a dimensional reduction, they not only derive the basic form of the effective surface Hamiltonian but also express its emergent elastic couplings as trans-membrane moments of lower-level material parameters. In the present paper, we argue, though, that their derivation unfortunately missed a coupling term between curvature and tilt. This term arises because, as one moves along the membrane, the curvature-induced change of transverse distances contributes to the area strain—an effect that was believed to be small but nevertheless ends up contributing at the same (quadratic) order as all other terms in their Hamiltonian. We illustrate the consequences of this amendment by deriving the monolayer and bilayer Euler-Lagrange equations for the tilt, as well as the power spectra of shape, tilt, and director fluctuations. A particularly curious aspect of our new term is that its associated coupling constant is the second moment of the lipid monolayer's lateral stress profile—which within this framework is equal to the monolayer Gaussian curvature modulus, κ¯ m. On the one hand, this implies that many theoretical predictions now contain a parameter that is poorly known (because the Gauss-Bonnet theorem limits access to the integrated Gaussian curvature); on the other hand, the appearance of κ¯ m outside of its Gaussian curvature provenance opens opportunities for measuring it by more conventional means, for instance by monitoring a membrane's undulation spectrum at short scales.

  18. Modeling Flow Past a Tilted Vena Cava Filter

    Energy Technology Data Exchange (ETDEWEB)

    Singer, M A; Wang, S L

    2009-06-29

    Inferior vena cava filters are medical devices used to prevent pulmonary embolism (PE) from deep vein thrombosis. In particular, retrievable filters are well-suited for patients who are unresponsive to anticoagulation therapy and whose risk of PE decreased with time. The goal of this work is to use computational fluid dynamics to evaluate the flow past an unoccluded and partially occluded Celect inferior vena cava filter. In particular, the hemodynamic response to thrombus volume and filter tilt is examined, and the results are compared with flow conditions that are known to be thrombogenic. A computer model of the filter inside a model vena cava is constructed using high resolution digital photographs and methods of computer aided design. The models are parameterized using the Overture software framework, and a collection of overlapping grids is constructed to discretize the flow domain. The incompressible Navier-Stokes equations are solved, and the characteristics of the flow (i.e., velocity contours and wall shear stresses) are computed. The volume of stagnant and recirculating flow increases with thrombus volume. In addition, as the filter increases tilt, the cava wall adjacent to the tilted filter is subjected to low velocity flow that gives rise to regions of low wall shear stress. The results demonstrate the ease of IVC filter modeling with the Overture software framework. Flow conditions caused by the tilted Celect filter may elevate the risk of intrafilter thrombosis and facilitate vascular remodeling. This latter condition also increases the risk of penetration and potential incorporation of the hook of the filter into the vena caval wall, thereby complicating filter retrieval. Consequently, severe tilt at the time of filter deployment may warrant early clinical intervention.

  19. Slant-tilt: the visual encoding of surface orientation.

    Science.gov (United States)

    Stevens, K A

    1983-01-01

    A specific form for the internal representation of local surface orientation is proposed, which is similar to Gibson's (1950) "amount and direction of slant". Slant amount is usually quantified by the angle sigma between the surface normal and the line of sight (0 degrees less than or equal to sigma less than or equal to 90 degrees). Slant direction corresponds to the direction of the gradient of distance from the viewer to the surface, and may be defined by the image direction tau to which the surface normal would project (0 degrees less than or equal to tau less than or equal to 360 degrees). Since the direction of slant is specified by the tilt of the projected surface normal, it is referred to as surface tilt (Stevens, 1979; Marr, 1982). The two degrees of freedom of orientation are therefore quantified by slant, an angle measured perpendicular to the image plane, and tilt, an angle measured in the image plane. The slant-tilt form provides several computational advantages relative to some other proposals and is consistent with various psychological phenomena. Slant might be encoded by various means, e.g. by the cosine of the angle, by the tangent, or linearly by the angle itself. Experimental results are reported that suggest that slant is encoded by an internal parameter that varies linearly with slant angle, with resolution of roughly one part in 100. Thus we propose that surface orientation is encoded in human vision by two quantities, one varying linearly with slant angle, the other varying linearly with tilt angle.

  20. Motion sickness and tilts of the inertial force environment : Active suspension systems vs. active passengers

    NARCIS (Netherlands)

    Golding, J. F.; van der Bles, W.; Bos, J. E.; Haynes, T.; Gresty, M. A.

    2003-01-01

    Background: Maneuvering in vehicles exposes occupants to low frequency forces (<1 Hz) which can provoke motion sickness. Hypothesis: Aligning with the tilting inertial resultant (gravity + imposed horizontal acceleration: gravito-inertial force (GIF)) may reduce motion sickness when tilting is

  1. Highly transparent and flexible bio-based polyimide/TiO2 and ZrO2 hybrid films with tunable refractive index, Abbe number, and memory properties.

    Science.gov (United States)

    Huang, Tzu-Tien; Tsai, Chia-Liang; Tateyama, Seiji; Kaneko, Tatsuo; Liou, Guey-Sheng

    2016-07-07

    The novel bio-based polyimide (4ATA-PI) and the corresponding PI hybrids of TiO2 or ZrO2 with excellent optical properties and thermal stability have been prepared successfully. The highly transparent 4ATA-PI containing carboxylic acid groups in the backbone could provide reaction sites for organic-inorganic bonding to obtain homogeneous hybrid films. These PI hybrid films showed a tunable refractive index (1.60-1.81 for 4ATA-PI/TiO2 and 1.60-1.80 for 4ATA-PI/ZrO2), and the 4ATA-PI/ZrO2 hybrid films revealed a higher optical transparency and Abbe's number than those of the 4ATA-PI/TiO2 system due to a larger band gap of ZrO2. By introducing TiO2 and ZrO2 as the electron acceptor into the 4ATA-PI system, the hybrid materials have a lower LUMO energy level which could facilitate and stabilize the charge transfer complex. Therefore, memory devices derived from these PI hybrid films exhibited tunable memory properties from DRAM, SRAM, to WORM with a different TiO2 or ZrO2 content from 0 wt% to 50 wt% with a high ON/OFF ratio (10(8)). In addition, the different energy levels of TiO2 and ZrO2 revealed specifically unique memory characteristics, implying the potential application of the prepared 4ATA-PI/TiO2 and 4ATA-PI/ZrO2 hybrid films in highly transparent memory devices.

  2. Effect of tilting on cerebral hemodynamics in preterm and term infants

    NARCIS (Netherlands)

    Pichler, G; van Boetzelar, MC; Muller, W; Urlesberger, B

    2001-01-01

    Tilting is known to cause changes in hemodynamics due to hydrostatic pressure. The present study is an analysis of changes in cerebral hemodynamics measured by near infrared spectroscopy (NIRS) following tilting up and down in preterm and term infants. A significantly different effect of tilting up

  3. Role of Baroreflex Sensitivity in Predicting Tilt Training Response in Patients with Neurally Mediated Syncope.

    Science.gov (United States)

    Chun, Kwang Jin; Yim, Hye Ran; Park, Jungwae; Park, Seung Jung; Park, Kyoung Min; On, Young Keun; Kim, June Soo

    2016-03-01

    An association between baroreflex sensitivity (BRS) and the response to tilt training has not been reported in patients with neurally mediated syncope (NMS). This study sought to investigate the role of BRS in predicting the response to tilt training in patients with NMS. We analyzed 57 patients who underwent tilt training at our hospital. A responder to tilt training was defined as a patient with three consecutive negative responses to the head-up tilt test (HUT) during tilt training. After tilt training, 52 patients (91.2%) achieved three consecutive negative responses to the HUT. In the supine position before upright posture during the first session of tilt training for responders and non-responders, the mean BRS was 18.17 ± 10.09 ms/mm Hg and 7.99 ± 5.84 ms/mm Hg (p=0.008), respectively, and the frequency of BRS ≥ 8.945 ms/mm Hg was 45 (86.5%) and 1 (20.0%; p=0.004), respectively. Age, male gender, frequency of syncopal events before HUT, type of NMS, phase of positive HUT, total number of tilt training sessions, and mean time of tilt training did not differ between the study groups. In the multivariate analysis, BRS training. The BRS value in the supine position could be a predictor for determining the response to tilt training in patients with NMS who are being considered for inpatient tilt training.

  4. Tilted-axis wobbling in odd-mass nuclei

    Science.gov (United States)

    Budaca, R.

    2018-02-01

    A triaxial rotor Hamiltonian with a rigidly aligned high-j quasiparticle is treated by a time-dependent variational principle, using angular momentum coherent states. The resulting classical energy function has three unique critical points in a space of generalized conjugate coordinates, which can minimize the energy for specific ordering of the inertial parameters and a fixed angular momentum state. Because of the symmetry of the problem, there are only two unique solutions, corresponding to wobbling motion around a principal axis and, respectively, a tilted axis. The wobbling frequencies are obtained after a quantization procedure and then used to calculate E 2 and M 1 transition probabilities. The analytical results are employed in the study of the wobbling excitations of 135Pr nucleus, which is found to undergo a transition from low angular momentum transverse wobbling around a principal axis toward a tilted-axis wobbling at higher angular momentum.

  5. Profile stabilization of tilt mode in a Field Reversed Configuration

    Energy Technology Data Exchange (ETDEWEB)

    Cobb, J.W.; Tajima, T. [Texas Univ., Austin, TX (United States). Inst. for Fusion Studies; Barnes, D.C. [Los Alamos National Lab., NM (United States)

    1993-06-01

    The possibility of stabilizing the tilt mode in Field Reversed Configurations without resorting to explicit kinetic effects such as large ion orbits is investigated. Various pressure profiles, P({Psi}), are chosen, including ``hollow`` profiles where current is strongly peaked near the separatrix. Numerical equilibria are used as input for an initial value simulation which uses an extended Magnetohydrodynamic (MHD) model that includes viscous and Hall terms. Tilt stability is found for specific hollow profiles when accompanied by high values of separatrix beta, {beta}{sub sep}. The stable profiles also have moderate to large elongation, racetrack separatrix shape, and lower values of 3, average ratio of Larmor radius to device radius. The stability is unaffected by changes in viscosity, but the neglect of the Hall term does cause stable results to become marginal or unstable. Implications for interpretation of recent experiments are discussed.

  6. On the Design of Tilting-Pad Thrust Bearings

    DEFF Research Database (Denmark)

    Heinrichson, Niels

    2007-01-01

    Pockets are often machined in the surfaces of tilting-pad thrust bearings to allow for hydrostatic jacking in the start-up phase. Pockets and other recesses in the surfaces of bearing pads influence the pressure distribution and thereby the position of the pivot resulting in the most advantageous...... friction and a small pressure build-up. As in parallel-step bearings the recesses may also have a depth of the same order of magnitude as the oil film thickness. Such recesses are characterized by a strong pressure build-up caused by the reduction of the flow area at the end of the recess. Numerical models...... based on the Reynolds equation are used. They include the effects of variations of viscosity with temperature and the deformation of the bearing pads due to pressure and thermal gradients. The models are validated using measurements. Tilting-pad bearings of standard design are studied and the influences...

  7. Tilting-Pad Guide Bearing in Large Hydro-unit

    Directory of Open Access Journals (Sweden)

    Li-Feng Ma

    2000-01-01

    Full Text Available A new numerical method is proposed for predicting the nonlinearity of tilting-pad guide bearing oilfilm force in the rotor-bearing system in a large hydro-unit. Nonlinear displacement and velocity of the journal center, as well as nonlinear tilting angles and angular velocities of the pads in non-stationary Reynolds equation are taken into account. This method is also suited for other small rotor-bearing system. As an example, the response due to a momentarily created unbalance is Calculated. The nonlinear motion patterns of the pad and journal whirling orbit are obtained. Finally, the nonlinear orbit is compared to the linear one that could be calculated from linear stiffness and damping coefficients. It is shown that there are important differences between those two orbits and that the nonlinear simulation is more accurate.

  8. TILT-BASED PREDICTIVE TEXT INPUT CONCEPT FOR MOBILE DEVICES

    Directory of Open Access Journals (Sweden)

    Marcin Badurowicz

    2017-06-01

    Full Text Available In the paper authors are introducing the concept of usage of physical orientation of a mobile device, calculated using built-in environmental sensors like accelerometer, gyroscope and magnetometer for detection of tilting gesture. This gesture is used as an acceptance factor for the two next probable word solutions suggested to the user during text input. By performing the device tilt, the first or second word is being automatically put into the desired text field and new prediction is performed. The text predictions are calculated and stored directly on the device to maintain privacy protection. The founding concept of the software is being presented, as well as initial considerations and further plans. This solution is recommended especially to smartphone manufacturers like Microsoft, Samsung and Apple to deploy in their latest models.

  9. Tilted Foils Nuclear Spin Polarization at REX-ISOLDE

    CERN Document Server

    Törnqvist, Hans Toshihide

    2013-08-08

    This thesis will explain and summarize my work and involvement in experiments aimed at producing nuclear spin polarization of post-accelerated beams of ions with the tilted-foils technique at the REX-ISOLDE linear accelerator at CERN. Polarizing the nuclear spin of radioactive beams in particular may provide access to observables which may be difficult to obtain otherwise. Currently, the techniques commonly employed for nuclear spin polarization are restricted to specific nuclides and experimental measurement techniques. Tilted foils polarization may provide a new tool to extend the range of nuclides that can be polarized and the types of experiments that can be performed. The experiments rely not only on the production but also on the method to measure the degree of attained polarization. Two methods will be treated, based on particle scattering in Coulomb excitation that may be utilized for stable beams, and the $\\beta$-NMR that requires $\\beta$-decaying nuclei. The experimental setups and measurements will...

  10. Source tilting within the difference formulation for radiation transport

    Energy Technology Data Exchange (ETDEWEB)

    Luu, T; Brooks, E; Szoke, A

    2006-09-27

    We apply a heuristic technique known as 'source tilting' to a Monte Carlo solution for radiation transport, in the difference formulation, that otherwise employs a piecewise-constant treatment of the material temperature. Source tilting improves the accuracy of the piecewise-constant treatment, reducing the excessive energy flow that occurs in the thick limit. An analysis of the cause of excessive energy flow suggests an interpolation scheme that removes this defect, obtaining the correct diffusion limit flux between zones. The results obtained with our interpolation scheme agree almost identically to those of a self-consistent piecewise-linear treatment of the difference formulation while avoiding its additional costs. The resulting method is capable of providing robust and accurate calculations for problems involving optically thick zones. We comment on the monotonicity issues that arise when employing this transport method.

  11. Simulation of effusion from targets of tilted foils

    International Nuclear Information System (INIS)

    Mustapha, B.; Nolen, J.A.; Gomes, I.C.

    2004-01-01

    Replacing a target transverse to the beam by a 10 times thinner one tilted at about 6 o from the beam direction reduces the thickness for heat transfer and diffusion by a factor of 10 while keeping the same production thickness. This concept makes the target cool faster and therefore supports higher beam power. Monte-Carlo effusion simulations of targets based on this concept were carried out to find optimum target geometries for both fast and slow diffusion materials

  12. Can pelvic tilting be ignored in total hip arthroplasty?

    Directory of Open Access Journals (Sweden)

    Won Yong Shon

    2014-01-01

    CONCLUSION: The sagittal position of pelvis is a key factor in impingement and dislocation after total hip arthroplasty. Pelvic tilting affects the position of acetabular component in the sagittal plane of the body as compared with its anatomic position in the pelvis. We suggest a preoperative lateral view of spine-pelvis, in upright and supine position for evaluation of a corrective adaptation of the acetabular cup accordingly with pelvic balance.

  13. Conformally flat tilted Bianchi Type-V cosmological models in ...

    Indian Academy of Sciences (India)

    The model starts expanding with a big-bang at М = 0 and the expansion in the model stops at М = ∞ and = -2(Т + 2)¬. The model in general represents shearing, non-rotating and tilted universe. The expansion in the model decreases as time increases. For = 1 Т = 1, we have heat conduction vector Х1 = 0 Х4 = 0. When М ...

  14. Dynamic characteristics of polymer faced tilting pad journal bearings

    DEFF Research Database (Denmark)

    Simmons, Gregory F.; Cerda Varela, Alejandro Javier; Santos, Ilmar

    2014-01-01

    Dynamic characteristics of polymer faced tilting pad journal bearings are presented. Investigations are conducted using a single pad, load on pad configuration over a range of shaft speeds and loads. Two polyether ether ketone (PEEK) faced pads, one polytetrafluoroethylene (PTFE) faced pad and two...... for entirely PEEK pads compared to pads with a PEEK lining and steel backing. Similar effects were observed by using a softer (PTFE) pad liner with a steel backing....

  15. Discontinuity effects in dynamically loaded tilting pad journal bearings

    DEFF Research Database (Denmark)

    Thomsen, Kim; Klit, Peder; Vølund, Anders

    2011-01-01

    This paper describes two discontinuity effects that can occur when modelling radial tilting pad bearings subjected to high dynamic loads. The first effect to be treated is a pressure build-up discontinuity effect. The second effect is a contact-related discontinuity that disappears when a contact...... force is included in the theoretical model. Methods for avoiding the pressure build-up discontinuity effect are proposed....

  16. Tilt stability of rotating current rings with passive conductors

    International Nuclear Information System (INIS)

    Zweibel, E.G.; Pomphrey, N.

    1984-12-01

    We study the combined effects of rotation and resistive passive conductors on the stability of a rigid current in an external magnetic field. We present numerical and approximate analytical solutions to the equations of motion, which show that the ring is always tilt unstable on the resistive decay timescale of the conductors, although rotation and eddy currents may stabilize it over short times. Possible applications of our model include spheromaks which rotate or which are encircled by energetic particle rings

  17. Modeling of Tilting-Pad Journal Bearings with Transfer Functions

    Directory of Open Access Journals (Sweden)

    J. A. Vázquez

    2001-01-01

    Full Text Available Tilting-pad journal bearings are widely used to promote stability in modern rotating machinery. However, the dynamics associated with pad motion alters this stabilizing capacity depending on the operating speed of the machine and the bearing geometric parameters, particularly the bearing preload. In modeling the dynamics of the entire rotor-bearing system, the rotor is augmented with a model of the bearings. This model may explicitly include the pad degrees of freedom or may implicitly include them by using dynamic matrix reduction methods. The dynamic reduction models may be represented as a set of polynomials in the eigenvalues of the system used to determine stability. All tilting-pad bearings can then be represented by a fixed size matrix with polynomial elements interacting with the rotor. This paper presents a procedure to calculate the coefficients of polynomials for implicit bearing models. The order of the polynomials changes to reflect the number of pads in the bearings. This results in a very compact and computationally efficient method for fully including the dynamics of tilting-pad bearings or other multiple degrees of freedom components that interact with rotors. The fixed size of the dynamic reduction matrices permits the method to be easily incorporated into rotor dynamic stability codes. A recursive algorithm is developed and presented for calculating the coefficients of the polynomials. The method is applied to stability calculations for a model of a typical industrial compressor.

  18. Anomalous DC Hall response in noncentrosymmetric tilted Weyl semimetals

    Science.gov (United States)

    Mukherjee, S. P.; Carbotte, J. P.

    2018-03-01

    Weyl nodes come in pairs of opposite chirality. For broken time reversal symmetry (TR) they are displaced in momentum space by {Q} and the anomalous DC Hall conductivity σxy is proportional to {Q} at charge neutrality. For finite doping there are additive corrections to σxy which depend on the chemical potential as well as on the tilt (C ) of the Dirac cones and on their relative orientation. If inversion symmetry (I) is also broken the Weyl nodes are shifted in energy by an amount Q0 . This introduces further changes in σxy and we provide simple analytic formulas for these modifications for both type I (Ctype II (C>1 , overtilted) Weyl. For type I when the Weyl nodes have equal magnitude but oppositely directed tilts, the correction to σxy is proportional to the chemical potential μ and completely independent of the energy shift Q0 . When instead the tilts are parallel, the correction is linear in Q0 and μ drops out. For type II the corrections involve both μ and Q0 , are nonlinear and also involve a momentum cut off. We discuss the implied changes to the Nernst coefficient and to the thermal Hall effect of a finite Q0 .

  19. Numerical tilting compensation in microscopy based on wavefront sensing using transport of intensity equation method

    Science.gov (United States)

    Hu, Junbao; Meng, Xin; Wei, Qi; Kong, Yan; Jiang, Zhilong; Xue, Liang; Liu, Fei; Liu, Cheng; Wang, Shouyu

    2018-03-01

    Wide-field microscopy is commonly used for sample observations in biological research and medical diagnosis. However, the tilting error induced by the oblique location of the image recorder or the sample, as well as the inclination of the optical path often deteriorates the imaging quality. In order to eliminate the tilting in microscopy, a numerical tilting compensation technique based on wavefront sensing using transport of intensity equation method is proposed in this paper. Both the provided numerical simulations and practical experiments prove that the proposed technique not only accurately determines the tilting angle with simple setup and procedures, but also compensates the tilting error for imaging quality improvement even in the large tilting cases. Considering its simple systems and operations, as well as image quality improvement capability, it is believed the proposed method can be applied for tilting compensation in the optical microscopy.

  20. Le rôle du marketing dans la motivation de la demande des engrais chimiques cas de la région de Sidi-bel-abbès

    OpenAIRE

    Benali, Amina

    2014-01-01

    Dans le premier chapitre de la thése nous avons décrire les principes du marketing appliqués poue les engrais chimiques.le second chapitre traitera les différents facteurs marketing qui influencent l'achat des engrais cchez l'agriculteur.le troisiéme chapitre sera consacré à la présentation du secteur des Engrais et Agricole en Algérie.Le quatriéme chapitre abordera la situation agricole dans la wilaya de Sidi bel-abbés, en mettant l'accent sur l'utilisation des engrais chimiques dans cette z...

  1. Study of a Car Body Tilting System Using a Variable Link Mechanism: Fundamental Characteristics of Pendulum Motion and Strategy for Perfect Tilting

    Science.gov (United States)

    Yoshida, Hidehisa; Nagai, Masao

    This paper analyzes the fundamental dynamic characteristics of a tilting railway vehicle using a variable link mechanism for compensating both the lateral acceleration experienced by passengers and the wheel load imbalance between the inner and outer rails. The geometric relations between the center of rotation, the center of gravity, and the positions of all four links of the tilting system are analyzed. Then, equations of the pendulum motions of the railway vehicle body with a four-link mechanism are derived. A theoretically discussion is given on the geometrical shapes employed in the link mechanism that can simultaneously provide zero lateral acceleration and zero wheel load fluctuation. Then, the perfect tilting condition, which is the control target of the feedforward tilting control, is derived from the linear equation of tilting motion.

  2. Development and testing of a pelvic goniometer designed to measure pelvic tilt and hip flexion.

    Science.gov (United States)

    Sprigle, Stephen; Flinn, Nannette; Wootten, Mary; McCorry, Stephanie

    2003-06-01

    To determine the reliability and validity of a pelvic goniometer designed to measure the pelvic tilt and hip flexion during seated posture. Assessment of the seated posture requires measurement of the pelvis and hip. Determining accurate pelvic tilt and hip flexion angles during sitting is often difficult using standard techniques. A pelvic goniometer has been designed to measure pelvic tilt and hip flexion angle of persons in a seated posture. VALIDATION of the pelvic goniometer was done radiographically. Ten male volunteers sat in three postures--erect, forward or anterior tilt, and posterior tilt. Pelvic tilt and hip angle were recorded using radiographs and the pelvic goniometer. Reliability of pelvic and conventional goniometers was done using seated nondisabled subjects with physical therapists performing measurements. the average differences and correlation between the pelvic goniometer and radiographic measures were as follows--pelvic tilt: -4.9 degrees, 0.93; hip angle 1.2 degrees, 0.81. Reliability: average range of hip angle across three measures was about 3 degrees for both goniometers. The data indicate that the pelvic goniometer has utility in measuring pelvic tilt and hip angle, especially within the seated posture. Because it measures both pelvic tilt and hip angle, the pelvic goniometer has an advantage over conventional goniometers that only measure the latter. A valid and reliable tool that measures pelvic tilt and hip angle of persons in a seated posture is needed for clinical research and practice. Its applications include wheelchair seating evaluations and ergonomic assessments of seated workers.

  3. Tilt table testing in patients with suspected epilepsy1

    DEFF Research Database (Denmark)

    Edfors, R.; Erdal, J.; Rogvi-Hansen, B.

    2008-01-01

    BACKGROUND: Approximately 20-30% of patients with epilepsy are misdiagnosed and syncope often seems to be the mistaken cause. We re-evaluated patients referred to an epilepsy clinic where suspicion of neurally mediated (reflex) syncope were raised using tilt table testing (HUT). METHODS: HUT...... laboratory results and medical records of 120 consecutive patients were reviewed retrospectively over a period of 27 months. RESULTS: HUT was positive in 59 (49%) patients. Seventeen of 38 (45%) patients previously diagnosed with epilepsy and taking antiepileptic drugs were found to be misdiagnosed. Four...

  4. A computer simulation study of tilted smectic mesophases

    International Nuclear Information System (INIS)

    Withers, I.M.

    2000-05-01

    Results are presented from a series of simulations undertaken to determine the effect of a novel form of molecular biaxiality upon the phase behaviour of the well established Gay-Berne (GB) liquid crystal model. Firstly, the simulation of a bulk system interacting via the Internally-Rotated Gay Berne (IRGB) potential, which offers a single-site representation of a molecule rigidly constrained into a zig-zag conformation, is presented. The results of simulations performed for systems of IRGB particles with an aspect ratio of 3:1 confirm that the introduction of biaxiality into the model results in the destabilisation of the orientationally ordered phases. For particles with a sufficiently pronounced zig-zag conformation, this results in the complete destabilisation of the smectic A phase and the smectic B phase being replaced by the tilted smectic J phase. Following these observations, the effect upon the phase behaviour of increasing molecular elongation is also considered, with an increase in the aspect ratio from 3:1 to 4:1 resulting in the nematic and smectic J phases being replaced by smectic A and smectic G phases respectively. Secondly, a version of the IRGB potential modified to include a degree of molecular flexibility is considered. Results obtained from bulk systems interacting via the flexible IRGB for 3:1 and 4:1 molecules show that the introduction of flexibility results in the destabilisation of the smectic A phase and the stabilisation of the nematic and tilted hexatic phases. Finally, the effect upon the phase behaviour of the rigid IRGB model of the inclusion of a longitudinal linear quadrupole is examined. These results show that increasing quadrupole moment results in the destabilisation of the tilted hexatic phase, although the biaxial order parameter is increased with increasing quadrupole moment. There is no clear correlation between quadrupole magnitude and the other observed phase transitions, with the nematic and smectic A phases being

  5. The impact of gravity during head-up tilt

    DEFF Research Database (Denmark)

    Ottesen, Johnny T.; Olufsen, Mette; Smith, Brittany

    2011-01-01

    and the carotid sinuses in a healthy volunteer. During head-up tilt the head is lifted above the heart stimulating gravitational pooling of blood in the lower extremities. This shift in volume is followed by an increase in blood pressure in the lower body, while the pressure in the head decreases, while...... a model predicting hydrostatic height between the two locations. Results from this model were compared with measurements. Furthermore, we show, using a differential equations model predicting blood pressure, that it is possible to predict blood pressure measured at the level of the carotid sinuses using...

  6. Performance of a Tilt Current Meter in the Surf Zone

    DEFF Research Database (Denmark)

    Hansen, Asger Bendix; Carstensen, Stefan; Christensen, Drude Fritzbøger

    2017-01-01

    Tilt Current Meters (TCM’s) are relatively simple and inexpensive instruments for measuring currents in rivers and inthe sea. Their low cost and easy deployment means that a relatively large number of TCM’s can be deployed comparedto more conventional current meters such as Acoustic Doppler...... a number ofimportant challenges to the measurements as the hydrodynamic forcing changes and the oscillations of the TCM cannotnecessarily be averaged out as for a steady current. This study addresses some of these challenges by analyzing theperformance of a TCM in the surf zone where wave orbital motion...

  7. Edge Waves and Localization in Lattices Containing Tilted Resonators

    Directory of Open Access Journals (Sweden)

    Domenico Tallarico

    2017-06-01

    Full Text Available The paper presents the study of waves in a structured geometrically chiral solid. A special attention is given to the analysis of the Bloch-Floquet waves in a doubly periodic high-contrast lattice containing tilted resonators. Dirac-like dispersion of Bloch waves in the structure is identified, studied, and applied to wave-guiding and wave-defect interaction problems. The work is extended to the transmission problems and models of fracture, where localization and edge waves occur. The theoretical derivations are accompanied with numerical simulations and illustrations.

  8. Tilt table testing in patients with suspected epilepsy1

    DEFF Research Database (Denmark)

    Edfors, R.; Erdal, J.; Rogvi-Hansen, B.

    2008-01-01

    BACKGROUND: Approximately 20-30% of patients with epilepsy are misdiagnosed and syncope often seems to be the mistaken cause. We re-evaluated patients referred to an epilepsy clinic where suspicion of neurally mediated (reflex) syncope were raised using tilt table testing (HUT). METHODS: HUT...... of 21 patients with epilepsy (19%) had dual diagnoses of reflex syncope and epilepsy. CONCLUSION: HUT is an informative investigation when suspicions of reflex syncope are raised in patients referred to an epilepsy clinic. Reflex syncope is an important and common differential diagnosis of epilepsy...

  9. Descripción morfoagronómica de materiales de plátano (Musa AAB, ABB y banano (Musa AAA cultivados en San Andrés Isla Morpho-agronomic Description of Plantain (Musa AAB, ABB and Banana (Musa AAA Materials Grown in San Andres Island

    Directory of Open Access Journals (Sweden)

    Oscar Javier Parra Pachón

    2009-10-01

    Full Text Available Durante el primer semestre de 2005 se estudiaron los cultivares de plátano y banano en fincas y parcelas de 15 agricultores típicos participantes en programas conjuntos de la Secretaría de Agricultura y Pesca de San Andrés Isla y de la Universidad Nacional de Colombia sede Caribe. A partir de descriptores de INIBAP, IPGRI y CIRAD y revisiones bibliográficas.se describen morfológicamente los materiales de Musa cultivados en la Isla, así como las prácticas de los productores isleños, Se identificaron cuatro clones del subgrupo plátano (Musa AAB: un Hartón (‘Horse’ y tres Dominico-Hartón (‘Tallo Negro’, ‘Tallo Blanco’ y ‘Cincuenta’ del subgrupo ABB se hallaron un material de Bluggoe (‘Boscó’ y un Felipita. El subgrupo banano AAA presentó dos materiales Gros Michel (denominados Común y Chino y uno de banano (Rojo. El plátano tiene gran importancia para los agricultores de la Isla, siendo el Boscó el clon más aceptado entre consumidores por su adaptación a las condiciones edafológicas y climáticas. El banano es menos cultivado; ya que los suelos, el clima y las enfermedades como sigatoka negra, condicionaron el desarrollo de clones. El trabajo sugiere prácticas de fácil implementación que podrían aumentar la producción en los sistemas de huerto mixto tropical que predominan en la Isla.During the first semester, 2005 we studied the plantain and banana cultivars in small farms of 15 volunteer regular producers, who were participating in joint programs of the Agriculture and Fisheries Secretariat of San Andres Island and the Colombian National University Caribbean Headquarters. We described morphologically the Musa cultivars identified in the island, as well as agricultural practices of the island producers, using the INIBAP, IPGRI and CIRAD (1996 descriptors and bibliographical reviews. We identified four clones within the plantain sub-group Musa AAB: a Horn type and three French-Horn; and within the ABB

  10. Tilted seat position for non-ambulant individuals with neurological and neuromuscular impairment: a systematic review

    OpenAIRE

    Michael, SM; Porter, D; Pountney, TE

    2008-01-01

    Objective: To determine the effects of tilt-in-space seating on outcomes for people with neurological or neuromuscular impairment who cannot walk. Data sources: Search through electronic databases (MEDLINE, Embase, CINAHL, AMED). Discussions with researchers who are active in field. Review methods: Selection criteria included interventional studies that investigated the effects of seat tilt on outcome or observational studies that identified outcomes for those who had used tilt-in-space seati...

  11. Research on Calculation of the IOL Tilt and Decentration Based on Surface Fitting

    OpenAIRE

    Li, Lin; Wang, Ke; Yan, Yan; Song, Xudong; Liu, Zhicheng

    2013-01-01

    The tilt and decentration of intraocular lens (IOL) result in defocussing, astigmatism, and wavefront aberration after operation. The objective is to give a method to estimate the tilt and decentration of IOL more accurately. Based on AS-OCT images of twelve eyes from eight cases with subluxation lens after operation, we fitted spherical equation to the data obtained from the images of the anterior and posterior surfaces of the IOL. By the established relationship between IOL tilt (decentrati...

  12. Spontaneous tilting after placement of the gunther-tulip inferior vena caval filter: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Tae Seok; Cha, In Ho; Seol, Hae Young; Park, Cheol Min [Guro Hospital, Korea University College of Medicine, Seoul (Korea, Republic of)

    2006-10-15

    Tilting of a deployed filter in the inferior vena cava (IVC) is a particular kind of periprocedural complication and this can reduce the filter's clot-trapping ability and increase the occlusion of the IVC at a later period. The authors report here on a case of spontaneous tilting of an inferior vena caval filter that was associated with thrombosis in the IVC within 2 weeks of the initially successful placement of the filter without tilting.

  13. Spontaneous tilting after placement of the gunther-tulip inferior vena caval filter: a case report

    International Nuclear Information System (INIS)

    Seo, Tae Seok; Cha, In Ho; Seol, Hae Young; Park, Cheol Min

    2006-01-01

    Tilting of a deployed filter in the inferior vena cava (IVC) is a particular kind of periprocedural complication and this can reduce the filter's clot-trapping ability and increase the occlusion of the IVC at a later period. The authors report here on a case of spontaneous tilting of an inferior vena caval filter that was associated with thrombosis in the IVC within 2 weeks of the initially successful placement of the filter without tilting

  14. Tidal tilts observations in the Gran Sasso underground laboratory

    International Nuclear Information System (INIS)

    Iafolla, V.; Nozzoli, S.; Milyukov, V.

    2001-01-01

    A new tilt meter, based on the technology for building a space-borne high-sensitivity accelerometer and manufactured at IFSI/CNR, has a been operating during several years in the INFN Gran Sasso underground laboratory. The results of the analysis of a three-year data set, processed with the program package ETERNA, to estimate earth tidal parameters are reported. For the best series of data (1998) tide measurement accuracies are: 0.5-1% for the M 2 (lunar principal) amplitude and 3-4% for the O 1 (lunar declination) amplitude. The tilt meter installed at a depth of 1400 m shows no clear evidence of meteorological effects. Observed tidal parameters are compared with theoretical tidal parameters predicted for a non-hydrostatic inelastic Earth model and demonstrate good agreement for the M 2 component. Due to the high accuracy of the tidal components prediction (better than 1%) tidal measurements were used to estimate the long-term stability of the instrument response

  15. An efficient wave extrapolation method for anisotropic media with tilt

    KAUST Repository

    Waheed, Umair bin

    2015-03-23

    Wavefield extrapolation operators for elliptically anisotropic media offer significant cost reduction compared with that for the transversely isotropic case, particularly when the axis of symmetry exhibits tilt (from the vertical). However, elliptical anisotropy does not provide accurate wavefield representation or imaging for transversely isotropic media. Therefore, we propose effective elliptically anisotropic models that correctly capture the kinematic behaviour of wavefields for transversely isotropic media. Specifically, we compute source-dependent effective velocities for the elliptic medium using kinematic high-frequency representation of the transversely isotropic wavefield. The effective model allows us to use cheaper elliptic wave extrapolation operators. Despite the fact that the effective models are obtained by matching kinematics using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy trade-off for wavefield computations in transversely isotropic media, particularly for media of low to moderate complexity. In addition, the wavefield solution is free from shear-wave artefacts as opposed to the conventional finite-difference-based transversely isotropic wave extrapolation scheme. We demonstrate these assertions through numerical tests on synthetic tilted transversely isotropic models.

  16. Effective ellipsoidal models for wavefield extrapolation in tilted orthorhombic media

    KAUST Repository

    Waheed, Umair Bin

    2016-04-22

    Wavefield computations using the ellipsoidally anisotropic extrapolation operator offer significant cost reduction compared to that for the orthorhombic case, especially when the symmetry planes are tilted and/or rotated. However, ellipsoidal anisotropy does not provide accurate wavefield representation or imaging for media of orthorhombic symmetry. Therefore, we propose the use of ‘effective ellipsoidally anisotropic’ models that correctly capture the kinematic behaviour of wavefields for tilted orthorhombic (TOR) media. We compute effective velocities for the ellipsoidally anisotropic medium using kinematic high-frequency representation of the TOR wavefield, obtained by solving the TOR eikonal equation. The effective model allows us to use the cheaper ellipsoidally anisotropic wave extrapolation operators. Although the effective models are obtained by kinematic matching using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including frequency dependency and caustics, if present, with reasonable accuracy. The proposed methodology offers a much better cost versus accuracy trade-off for wavefield computations in TOR media, particularly for media of low to moderate anisotropic strength. Furthermore, the computed wavefield solution is free from shear-wave artefacts as opposed to the conventional finite-difference based TOR wave extrapolation scheme. We demonstrate applicability and usefulness of our formulation through numerical tests on synthetic TOR models. © 2016 Institute of Geophysics of the ASCR, v.v.i

  17. Evaluation of the Thermal Effects in Tilting Pad Bearing

    Directory of Open Access Journals (Sweden)

    G. B. Daniel

    2013-01-01

    Full Text Available The analysis of thermal effects is of expressive importance in the context of rotordynamics to evaluate the behavior of hydrodynamic bearings because these effects can influence their dynamic characteristics under specific operational conditions. For this reason, a thermohydrodynamic model is developed in this work, in which the pressure distribution in the oil film and the temperature distribution are calculated together. From the pressure distribution, the velocity distribution field is determined, as well as the viscous dissipation, and consequently, the temperature distribution. The finite volume method is applied to solve the Reynolds equation and the energy equation in the thermohydrodynamic model (THD. The results show that the temperature is higher as the rotational speed increases due to the shear rate of the oil film. The maximum temperature in the bearing occurs in the overloaded pad, near the outlet boundary. The experimental tests were performed in a tilting pad journal bearing operating in a steam turbine to validate the model. The comparison between the experimental and numerical results provides a good correlation. The thermohydrodynamic lubrication developed in this assignment is promising to consistently evaluate the behavior of the tilting pad journal bearing operating in relatively high rotational speeds.

  18. Direct experimental measurement of SRS-induced spectral tilt in multichannel multispan communication systems

    Energy Technology Data Exchange (ETDEWEB)

    Kapin, Yu A; Nanii, Oleg E; Novikov, A G; Pavlov, V N; Plotskii, A Yu; Treshchikov, V N

    2012-09-30

    Nonlinear SRS-induced tilt of the spectrum of a multichannel DWDM signal is studied experimentally in standard singlemode fibreoptic communication lines. It is found that at a fixed spectral bandwidth and total power the nonlinear SRS tilt is independent of the number of channels, radiation source type, and the initial tilt (positive or negative). In a multispan line consisting of identical spans the total nonlinear tilt of the spectrum (in dB) is proportional to the number of spans, spectral width and total power. (optical fibres, lasers and amplifiers. properties and applications)

  19. Research on calculation of the IOL tilt and decentration based on surface fitting.

    Science.gov (United States)

    Li, Lin; Wang, Ke; Yan, Yan; Song, Xudong; Liu, Zhicheng

    2013-01-01

    The tilt and decentration of intraocular lens (IOL) result in defocussing, astigmatism, and wavefront aberration after operation. The objective is to give a method to estimate the tilt and decentration of IOL more accurately. Based on AS-OCT images of twelve eyes from eight cases with subluxation lens after operation, we fitted spherical equation to the data obtained from the images of the anterior and posterior surfaces of the IOL. By the established relationship between IOL tilt (decentration) and the scanned angle, at which a piece of AS-OCT image was taken by the instrument, the IOL tilt and decentration were calculated. IOL tilt angle and decentration of each subject were given. Moreover, the horizontal and vertical tilt was also obtained. Accordingly, the possible errors of IOL tilt and decentration existed in the method employed by AS-OCT instrument. Based on 6-12 pieces of AS-OCT images at different directions, the tilt angle and decentration values were shown, respectively. The method of the surface fitting to the IOL surface can accurately analyze the IOL's location, and six pieces of AS-OCT images at three pairs symmetrical directions are enough to get tilt angle and decentration value of IOL more precisely.

  20. Research on Calculation of the IOL Tilt and Decentration Based on Surface Fitting

    Directory of Open Access Journals (Sweden)

    Lin Li

    2013-01-01

    Full Text Available The tilt and decentration of intraocular lens (IOL result in defocussing, astigmatism, and wavefront aberration after operation. The objective is to give a method to estimate the tilt and decentration of IOL more accurately. Based on AS-OCT images of twelve eyes from eight cases with subluxation lens after operation, we fitted spherical equation to the data obtained from the images of the anterior and posterior surfaces of the IOL. By the established relationship between IOL tilt (decentration and the scanned angle, at which a piece of AS-OCT image was taken by the instrument, the IOL tilt and decentration were calculated. IOL tilt angle and decentration of each subject were given. Moreover, the horizontal and vertical tilt was also obtained. Accordingly, the possible errors of IOL tilt and decentration existed in the method employed by AS-OCT instrument. Based on 6–12 pieces of AS-OCT images at different directions, the tilt angle and decentration values were shown, respectively. The method of the surface fitting to the IOL surface can accurately analyze the IOL’s location, and six pieces of AS-OCT images at three pairs symmetrical directions are enough to get tilt angle and decentration value of IOL more precisely.

  1. NUMERICAL SIMULATIONS OF NATURALLY TILTED, RETROGRADELY PRECESSING, NODAL SUPERHUMPING ACCRETION DISKS

    International Nuclear Information System (INIS)

    Montgomery, M. M.

    2012-01-01

    Accretion disks around black hole, neutron star, and white dwarf systems are thought to sometimes tilt, retrogradely precess, and produce hump-shaped modulations in light curves that have a period shorter than the orbital period. Although artificially rotating numerically simulated accretion disks out of the orbital plane and around the line of nodes generate these short-period superhumps and retrograde precession of the disk, no numerical code to date has been shown to produce a disk tilt naturally. In this work, we report the first naturally tilted disk in non-magnetic cataclysmic variables using three-dimensional smoothed particle hydrodynamics. Our simulations show that after many hundreds of orbital periods, the disk has tilted on its own and this disk tilt is without the aid of radiation sources or magnetic fields. As the system orbits, the accretion stream strikes the bright spot (which is on the rim of the tilted disk) and flows over and under the disk on different flow paths. These different flow paths suggest the lift force as a source to disk tilt. Our results confirm the disk shape, disk structure, and negative superhump period and support the source to disk tilt, source to retrograde precession, and location associated with X-ray and He II emission from the disk as suggested in previous works. Our results identify the fundamental negative superhump frequency as the indicator of disk tilt around the line of nodes.

  2. Comparative analysis of diffused solar radiation models for optimum tilt angle determination for Indian locations

    International Nuclear Information System (INIS)

    Yadav, P.; Chandel, S.S.

    2014-01-01

    Tilt angle and orientation greatly are influenced on the performance of the solar photo voltaic panels. The tilt angle of solar photovoltaic panels is one of the important parameters for the optimum sizing of solar photovoltaic systems. This paper analyses six different isotropic and anisotropic diffused solar radiation models for optimum tilt angle determination. The predicted optimum tilt angles are compared with the experimentally measured values for summer season under outdoor conditions. The Liu and Jordan model is found to exhibit t lowest error as compared to other models for the location. (author)

  3. SPECT imaging: Experimental determination of the effect of camera head tilt and appropriate quality control protocol

    International Nuclear Information System (INIS)

    Farrell, T.J.; Cradduck, T.D.

    1985-01-01

    Although it is recognized in SPECT imaging that the camera face shall remain parallel to the axis of rotation there is no evidence of the limits that must be imposed on this parameter for acceptable reconstruction of the data. This study was made with the purpose of establishing limits of camera head tilt based on experiments designed to measure degradation of the image with increasing camera head tilt. The effect of camera head tilt is to place off-axis data in the wrong plane for reconstruction. Points off axis exhibit a pseudomotion along a line parallel to the axis of rotation so that data from one plane are ''seen'' by the reconstruction algorithm to be in different planes, depending on the angle of rotation. The changes in system resolution due to camera head tilt were assessed using the cold spheres in a Jaszczak phantom. The contrast of the spheres was measured for increasing angles of head tilt. Significant degradation occurred at tilt angles as low as one degree. Based on these observations a quality control procedure for camera head tilt was developed. A point source is imaged off-axis and a computer program has been written that is able to give the angle of head tilt based on the pseudomotion of the point source throughout the rotation of the camera head. This method can be used to calibrate the head tilt angle. It is evident that the camera head tilt must be checked for every patient study. Unlike center of rotation offsets, it is not possible to correct the raw data for camera head tilt during reconstruction

  4. 'Sit and tilt' preparation for subscapular system free flaps.

    Science.gov (United States)

    Mark, J; Patwa, H; Costello, M S; Patil, Y

    2018-02-01

    The ablation of advanced head and neck cancer often results in large three-dimensional defects that require free tissue transfer to optimally address functional and cosmetic issues. The subscapular system is a highly versatile donor site for flaps used for head and neck reconstruction. Traditional methods of harvesting subscapular flaps require repositioning and re-preparing, which significantly increases the operative time and prevents simultaneous harvesting of the flap. This paper presents our experience of a single-stage 'sit and tilt' technique, which provides a convenient method for harvesting subscapular system free flaps without significant repositioning. This technique was used for a variety of head and neck defects, and body habitus did not seem to affect free tissue harvesting. It is hoped that utilisation of this preparation and harvesting technique will make head and neck surgeons more willing to take advantage of the subscapular system.

  5. Experimental study of the distillation process in a tilted cavity

    Science.gov (United States)

    Wang, Xihui; Chen, Houtao; Wang, Zhijie; Xiao, Gang

    2017-05-01

    Heat and mass transfer correlations in a basin solar still are not applicable for brine-flowing type solar still. Thermal efficiency is hard to determine explicitly due to the varying temperature of brine along the flow direction. A simple method is proposed in the present work to evaluate the performance of the brine-flowing type still through the energy balance equation of brine. Experiments in a tilted cavity which is used to simulate a brine-flowing type solar still are conducted, and it is found that thermal efficiency of the simulated still is always less than 76.3%. An empirical equation is obtained, which may provide a clue for the development of an explicit theoretical model to predict fresh water production of the brine-flowing solar still.

  6. Rain Sensor with Stacked Light Waveguide Having Tilted Air Gap

    Directory of Open Access Journals (Sweden)

    Kyoo Nam Choi

    2014-01-01

    Full Text Available Vehicle sensor to detect rain drop on and above waveguide utilizing light deflection and scattering was realized, keeping wide sensing coverage and sensitivity to detect mist accumulation. Proposed sensor structure under stacked light wave guide consisted of light blocking fixture surrounding photodetector and adjacent light source. Tilted air gap between stacked light waveguide and light blocking fixture played major role to increase sensitivity and to enhance linearity. This sensor structure eliminated complex collimating optics, while keeping wide sensing coverage using simple geometry. Detection algorithm based on time-to-intensity transformation process was used to convert raining intensity into countable raining process. Experimental result inside simulated rain chamber showed distinct different response between light rain and normal rain. Application as automobile rain sensor is expected.

  7. Patient Specific Modeling of Head-Up Tilt

    DEFF Research Database (Denmark)

    Williams, Nakeya; Wright, Andrew; Mehlsen, Jesper

    2014-01-01

    blood pressure. The model contains five compartments representing arteries and veins in the upper and lower body of the systemic circulation, as well as the left ventricle facilitating pumping of the heart. A physiologically based sub-model describes gravitational effects on pooling of blood during......Short term cardiovascular responses to head-up tilt (HUT) experiments involve complex cardiovascular regulation in order to maintain blood pressure at homeostatic levels. This manuscript presents a patient specific compartmental model developed to predict dynamic changes in heart rate and arterial...... that it is possible to estimate a subset of model parameters that allows prediction of observed changes in arterial blood pressure. Furthermore, the model adequately predicts arterial and venous blood pressures, as well as cardiac output in compartments for which data are not available....

  8. Comparison of scapular posterior tilting exercise alone and scapular posterior tilting exercise after pectoralis minor stretching on scapular alignment and scapular upward rotators activity in subjects with short pectoralis minor.

    Science.gov (United States)

    Lee, Ji-Hyun; Cynn, Heon-Seock; Yoon, Tae-Lim; Choi, Sil-Ah; Choi, Woo-Jeong; Choi, Bong-Sam; Ko, Chang-Hee

    2015-08-01

    To compare scapular posterior tilting exercise alone and scapular posterior tilting exercise after pectoralis minor (PM) stretching on the PM index (PMI), scapular anterior tilting index, scapular upward rotation angle, and scapular upward rotators' activity in subjects with a short PM. Fifteen subjects with a short PM participated in this study. The PMI, scapular anterior tilting index, and scapular upward rotation angle were measured after scapular posterior tilting exercise alone and scapular posterior tilting exercise after PM stretches. Scapular upward rotators' activities were collected during scapular posterior tilting exercise alone and scapular posterior tilting exercise after PM stretches. The PMI and scapular upward rotation angle, as well as the activity of the upper trapezius, lower trapezius, and serratus anterior muscles, were significantly greater for scapular posterior tilting exercise after PM stretching and the scapular anterior tilting index was significantly lower for scapular posterior tilting exercise after PM stretching than the scapular posterior tilting exercise alone. Scapular posterior tilting exercise after PM stretching in subjects with a short PM could be an effective method of modifying scapular alignment and scapular upward rotator activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. A Psychometric Investigation of Gender-Tilted Families: Implications for Family Therapy.

    Science.gov (United States)

    Falconer, Clark W.; And Others

    1990-01-01

    Obtained self-reports from 40 couples from gender-tilted families, families which have several children of same sex. Parents of boys reported higher levels of family conflict and lower satisfaction with their families than did parents of girls. Parents of male-tilted families expressed more masculine sex-role orientations, greater personal…

  10. Patients with severe acquired brain injury show increased arousal in tilt-table training

    DEFF Research Database (Denmark)

    Riberholt, Christian G; Thorlund, Jonas Bloch; Mehlsen, Jesper

    2013-01-01

    Patients with severe acquired brain injury (ABI) are often mobilised using a tilt-table. Complications such as orthostatic intolerance have been reported. The primary objective of this study was to investigate if using a tilt-table was feasible for mobilising patients with severe ABI admitted...

  11. The Application of Normal Stress Reduction Function in Tilt Tests for Different Block Shapes

    Science.gov (United States)

    Kim, Dong Hyun; Gratchev, Ivan; Hein, Maw; Balasubramaniam, Arumugam

    2016-08-01

    This paper focuses on the influence of the shapes of rock cores, which control the sliding or toppling behaviours in tilt tests for the estimation of rock joint roughness coefficients (JRC). When the JRC values are estimated by performing tilt tests, the values are directly proportional to the basic friction of the rock material and the applied normal stress on the sliding planes. Normal stress obviously varies with the shape of the sliding block, and the basic friction angle is also affected by the sample shapes in tilt tests. In this study, the shapes of core blocks are classified into three representative shapes and those are created using plaster. Using the various shaped artificial cores, a set of tilt tests is carried out to identify the shape influences on the normal stress and the basic friction angle in tilt tests. The test results propose a normal stress reduction function to estimate the normal stress for tilt tests according to the sample shapes based on Barton's empirical equation. The proposed normal stress reduction functions are verified by tilt tests using artificial plaster joints and real rock joint sets. The plaster joint sets are well matched and cast in detailed printed moulds using a 3D printing technique. With the application of the functions, the obtained JRC values from the tilt tests using the plaster samples and the natural rock samples are distributed within a reasonable JRC range when compared with the measured values.

  12. Optimum Tilt Angle for Photovoltaic Solar Panels in Zomba District, Malawi

    Directory of Open Access Journals (Sweden)

    B. Kamanga

    2014-01-01

    Full Text Available A study to determine the optimum tilt angle for installing photovoltaic solar panels in Zomba district, Malawi, has been conducted. The study determined the optimum monthly tilt angles of PV solar panels and the seasonal adjustments needed for the panels in order to collect maximum solar radiation throughout the year. In this study, global solar radiation (GSR on four tilted surfaces was measured. The north-facing surfaces were titled at angles of 0°, 15°, 20°, and 25°. The GSR data was used to determine the daily and monthly optimum tilt angles for the PV panels. The optimum tilt angles were found to be 0° or 25° depending on the time of the year. From October to February, the optimum tilt angle has been determined to be 0° and, from March to September, the optimum tilt angle is observed to be 25°. There are only two seasonal adjustments that are needed for PV solar panels in Zomba district and these should be carried out at the end of February and at the end of September. For fixed solar panels with no seasonal adjustments, the optimum tilt angle for the PV solar panels that are northfacing has been determined to be 25°.

  13. Switching PD-based sliding mode control for hovering of a tilting-thruster underwater robot.

    Science.gov (United States)

    Jin, Sangrok; Bak, Jeongae; Kim, Jongwon; Seo, TaeWon; Kim, Hwa Soo

    2018-01-01

    This paper presents a switching PD-based sliding mode control (PD-SMC) method for the 6-degree-of-freedom (DOF) hovering motion of the underwater robot with tilting thrusters. Four thrusters of robot can be tilted simultaneously in the horizontal and vertical directions, and the 6-DOF motion is achieved by switching between two thruster configurations. Therefore, the tilting speed of thruster becomes the most essential parameter to determine the stability of hovering motion. Even though the previous PD control ensures stable hovering motion within a certain ranges of tilting speed, a PD-SMC is suggested in this paper by combining PD control with sliding mode control in order to achieve acceptable hovering performance even at the much lower tilting speeds. Also, the sign function in the sliding mode control is replaced by a sigmoid function to reduce undesired chattering. Simulations show that while PD control is effective only for tilting duration of 600 ms, the PD-based sliding mode control can guarantee the stable hovering motion of underwater robot even for the tilting duration of up to 1500 ms. Extensive experimental results confirm the hovering performance of the proposed PD-SMC method is much superior to that of PD method for much larger tilting durations.

  14. On the simplifications for the thermal modeling of tilting-pad journal bearings under thermoelastohydrodynamic regime

    DEFF Research Database (Denmark)

    Cerda Varela, Alejandro Javier; Fillon, Michel; Santos, Ilmar

    2012-01-01

    The relevance of calculating accurately the oil film temperature build up when modeling tilting-pad journal bearings is well established within the literature on the subject. This work studies the feasibility of using a thermal model for the tilting-pad journal bearing which includes a simplified...

  15. The effect of tilt angle on the performance of evacuated tube solar air ...

    African Journals Online (AJOL)

    The evacuated tube solar air collector had different collector tilt angles from the horizontal with the one inclined at 30° and 45°. Experimental results revealed that tilt angle had significant influence on the thermal performance of the evacuated tube solar air collector along with or without reflector. Experiments also showed ...

  16. Gravito-Inertial Force Resolution in Perception of Synchronized Tilt and Translation

    Science.gov (United States)

    Wood, Scott J.; Holly, Jan; Zhang, Guen-Lu

    2011-01-01

    Natural movements in the sagittal plane involve pitch tilt relative to gravity combined with translation motion. The Gravito-Inertial Force (GIF) resolution hypothesis states that the resultant force on the body is perceptually resolved into tilt and translation consistently with the laws of physics. The purpose of this study was to test this hypothesis for human perception during combined tilt and translation motion. EXPERIMENTAL METHODS: Twelve subjects provided verbal reports during 0.3 Hz motion in the dark with 4 types of tilt and/or translation motion: 1) pitch tilt about an interaural axis at +/-10deg or +/-20deg, 2) fore-aft translation with acceleration equivalent to +/-10deg or +/-20deg, 3) combined "in phase" tilt and translation motion resulting in acceleration equivalent to +/-20deg, and 4) "out of phase" tilt and translation motion that maintained the resultant gravito-inertial force aligned with the longitudinal body axis. The amplitude of perceived pitch tilt and translation at the head were obtained during separate trials. MODELING METHODS: Three-dimensional mathematical modeling was performed to test the GIF-resolution hypothesis using a dynamical model. The model encoded GIF-resolution using the standard vector equation, and used an internal model of motion parameters, including gravity. Differential equations conveyed time-varying predictions. The six motion profiles were tested, resulting in predicted perceived amplitude of tilt and translation for each. RESULTS: The modeling results exhibited the same pattern as the experimental results. Most importantly, both modeling and experimental results showed greater perceived tilt during the "in phase" profile than the "out of phase" profile, and greater perceived tilt during combined "in phase" motion than during pure tilt of the same amplitude. However, the model did not predict as much perceived translation as reported by subjects during pure tilt. CONCLUSION: Human perception is consistent with

  17. Performance verification of focus variation and confocal microscopes measuring tilted ultra-fine surfaces

    DEFF Research Database (Denmark)

    Quagliotti, Danilo; Baruffi, Federico; Tosello, Guido

    2016-01-01

    The behaviour of two optical instruments, scilicet a laser scanning confocal microscope and a focus-variation microscope, was investigated considering measurements of tilted surfaces. The measured samples were twelve steel artefacts for mould surface finish reference, covering Sa roughness...... parameter in the range (101—103) nm. The 3D surface texture parameters considered were Sa, Sq and Sdq. The small working distance of the confocal microscope objectives influenced the measurement setup, preventing from selecting a high tilting angle. The investigation was carried out comparing measurements...... of flat surfaces (0° tilt) with measurements of 12.5° tilted surfaces. The confocal microscope results showed a high sensitivity to tilting due to the laser beam reflection on the metal surfaces. The focus variation microscope results were more robust with respect to the considered angular variation...

  18. Validation of Tilt Gain under Realistic Path Loss Model and Network Scenario

    DEFF Research Database (Denmark)

    Nguyen, Huan Cong; Rodriguez, Ignacio; Sørensen, Troels Bundgaard

    2013-01-01

    Despite being a simple and commonly-applied radio optimization technique, the impact on practical network performance from base station antenna downtilt is not well understood. Most published studies based on empirical path loss models report tilt angles and performance gains that are far higher...... than practical experience suggests. We motivate in this paper, based on a practical LTE scenario, that the discrepancy partly lies in the path loss model, and shows that a more detailed semi-deterministic model leads to both lower gains in terms of SINR, outage probability and downlink throughput...... and lower optimum tilt settings. Furthermore, we show that a simple geometrically based tilt optimization algorithm can outperform other tilt profiles, including the setting applied by the cellular operator in the specific case. In general, the network performance is not highly sensitive to the tilt...

  19. Construire une société seigneuriale. Itinéraire et ecclésiologie de l’abbé Odon de Cluny (fin du IXe-milieu du Xe siècle

    Directory of Open Access Journals (Sweden)

    Isabelle Rosé

    2009-11-01

    Full Text Available Entre la fin du IXe et le milieu du Xe siècle, de nouvelles formes de pouvoir émergent en Occident, au sein de cadres encore partiellement carolingiens. Il s’agit d’un bouleversement majeur qui marque la genèse de la société seigneuriale. Cette époque de transition a alimenté et suscite encore de nombreux débats qui portent sur la chronologie et les modalités du passage d’un type d’organisation sociale à un autre. C’est cette période charnière que permet d’appréhender le deuxième abbé de Clun...

  20. In-vitro hemodynamics of stented bioprosthetic heart valves in the tilted implantation position.

    Science.gov (United States)

    Babin-Ebell, Joerg; Sievers, Hans H; Misfeld, Martin; Runge, Maike; Vogt, Paul Robert; Scharfschwerdt, Michael

    2008-09-01

    Although, in small aortic annulus or aortic annulus calcification, it is recommended that valves are implanted in a tilted position, mechanical valves show impaired hemodynamic performance when positioned in this way. To date, no investigations have been conducted with biological valves implanted in a tilted position. Measurements were performed in a pulsatile flow simulator. The aortic roots were mounted in a fluid reservoir and tested with bioprosthetic valves implanted in the regular position (21 mm; n = 7) or at a 200 tilt (23 mm; n = 7). Additional 21 mm valves were implanted in both positions with a systemic pressure of 120/80 mmHg. Subsequently, the valves were implanted into a glass model and flow visualization monitored by adding air bubbles illuminated with a laser diode. The 21 mm valves showed a slightly higher transvalvular gradient in the tilted than in the regular position, while 23 mm valves in a tilted position showed a lower gradient than 21 mm valves in the regular position. Flow in the regular position was seen to be straight and central, but in the tilted position was diverted and impacted on the aortic wall. Vortex formation in the tilted position was more pronounced than in the regular position, with certain low-flow areas being observed. The implantation of a one size-larger bioprosthetic valve at a 20 degree tilt in a small aortic root resulted in a slight reduction in transvalvular gradient compared to a smaller valve implanted in the regular position. Whilst mechanical valve performance is markedly compromised in the tilted position, the bioprosthetic valve showed only minor impairment of transvalvular pressure gradient due to tilting, and this was overcompensated by the larger valve size. However, the advantage of a greater orifice area must be traded against the consequences of the observed flow disturbances.

  1. Evaluation of tilted cone-beam CT orbits in the development of a dedicated hybrid mammotomograph

    Energy Technology Data Exchange (ETDEWEB)

    Madhav, P; Crotty, D J; Tornai, M P [Department of Radiology, Duke University Medical Center, Durham, NC 27710 (United States); McKinley, R L [Zumatek Incorporated, Chapel Hill, NC 27519 (United States)], E-mail: priti.madhav@duke.edu

    2009-06-21

    A compact dedicated 3D breast SPECT-CT (mammotomography) system is currently under development. In its initial prototype, the cone-beam CT sub-system is restricted to a fixed-tilt circular rotation around the patient's pendant breast. This study evaluated stationary-tilt angles for the CT sub-system that will enable maximal volumetric sampling and viewing of the breast and chest wall. Images of geometric/anthropomorphic phantoms were acquired using various fixed-tilt circular and 3D sinusoidal trajectories. The iteratively reconstructed images showed more distortion and attenuation coefficient inaccuracy from tilted cone-beam orbits than from the complex trajectory. Additionally, line profiles illustrated cupping artifacts in planes distal to the central plane of the tilted cone-beam, otherwise not apparent for images acquired with complex trajectories. This indicates that undersampled cone-beam data may be an additional cause of cupping artifacts. High-frequency objects could be distinguished for all trajectories, but their shapes and locations were corrupted by out-of-plane frequency information. Although more acrylic balls were visualized with a fixed-tilt and nearly flat cone-beam at the posterior of the breast, 3D complex trajectories have less distortion and more complete sampling throughout the reconstruction volume. While complex trajectories would ideally be preferred, negatively fixed-tilt source-detector configuration demonstrates minimally distorted patient images.

  2. Tilted microstrip phased arrays with improved electromagnetic decoupling for ultrahigh-field magnetic resonance imaging.

    Science.gov (United States)

    Pang, Yong; Wu, Bing; Jiang, Xiaohua; Vigneron, Daniel B; Zhang, Xiaoliang

    2014-12-01

    One of the technical challenges in designing a dedicated transceiver radio frequency (RF) array for MR imaging in humans at ultrahigh magnetic fields is how to effectively decouple the resonant elements of the array. In this work, we propose a new approach using tilted microstrip array elements for improving the decoupling performance and potentially parallel imaging capability. To investigate and validate the proposed design technique, an 8-channel volume array with tilted straight-type microstrip elements was designed, capable for human imaging at the ultrahigh field of 7 Tesla. In this volume transceiver array, its electromagnetic decoupling behavior among resonant elements, RF field penetration to biological samples, and parallel imaging performance were studied through bench tests and in vivo MR imaging experiments. In this specific tilted element array design, decoupling among array elements changes with the tilted angle of the elements and the best decoupling can be achieved at certain tilted angle. In vivo human knee MR images were acquired using the tilted volume array at 7 Tesla for method validation. Results of this study demonstrated that the electromagnetic decoupling between array elements and the B1 field strength can be improved by using the tilted element method in microstrip RF coil array designs at the ultrahigh field of 7T.

  3. Marginal bone loss around tilted implants in comparison to straight implants: a meta-analysis.

    Science.gov (United States)

    Monje, Alberto; Chan, Hsun-Liang; Suarez, Fernando; Galindo-Moreno, Pablo; Wang, Hom-Lay

    2012-01-01

    The primary aim of this systematic review was to compare the amount of marginal bone loss around tilted and straight implants. As the secondary aim, the incidence of biomechanic complications was compared. An electronic literature search from five databases, for the years 2000 to 2011, and a hand search in implant-related journals were conducted. Clinical human studies in the English language that had reported marginal bone loss in tilted and straight implants at 12-months follow-up or longer were included. Mean marginal bone loss and the number of implants that were available for analysis were extracted from original articles for meta-analyses. Eight (six prospective and two retrospective) studies were included. One-year data were available in seven articles, which included 1,015 (451 tilted) implants. Three articles provided 3- to 5-year data from 302 (164 tilted) implants. No significant difference in weighted mean marginal bone loss was found between the tilted and straight implants in the short and medium terms. Three articles reported the incidence of biomechanic complications. There was not enough information to make a comparison. This meta-analysis failed to support the hypothesis that tilted implants that were splinted for the support of fixed prostheses had more marginal bone loss. Additionally, there was not enough evidence to claim a higher incidence of biomechanic complications in tilted implants. However, due to the nature of the study design of the included articles, caution should be exercised when interpreting the results of this review.

  4. Twenty-degree-tilt radiography for evaluation of lateral humeral condylar fracture in children

    International Nuclear Information System (INIS)

    Imada, Hideaki; Tanaka, Ryuji; Itoh, Yohei; Kishi, Kazuhiko

    2010-01-01

    To investigate the efficacy of '20 -tilt anteroposterior (A-P) radiography' in the assessment of lateral condylar fractures of the distal humerus. Eighteen children with lateral humeral condylar fractures were studied. Every child underwent conventional A-P and lateral radiography, and six children underwent multi-detector computed tomography (MDCT). For the investigation of 20 -tilt radiography, ten children with lateral humeral condylar fractures had conventional and 20 -tilt A-P and lateral radiography both preoperatively and postoperatively. Fragment dislocation was measured at the lateral and medial margins of the fracture on both the conventional A-P and 20 -tilt A-P radiographs. The lateral condylar fragment was triangular and was most prominent posteriorly. The fracture line was typically tilted approximately 20 to a reference line perpendicular to the long axis of the humerus in the lateral view. The extent of dislocation at the lateral and medial margins of the fracture site by 20 -tilt A-P radiography (9.3 ± 3.6 mm and 5.6 ± 2.5 mm) was significantly wider than that measured by the conventional method (6.8 ± 4.1 mm and 2.0 ± 1.5 mm), which may influence treatment. Twenty-degree-tilt A-P radiography may more precisely demonstrate fragment dislocation than standard radiographs and may influence patient treatment. (orig.)

  5. Comparative study of absorption in tilted silicon nanowire arrays for photovoltaics.

    Science.gov (United States)

    Kayes, Md Imrul; Leu, Paul W

    2014-01-01

    Silicon nanowire arrays have been shown to demonstrate light trapping properties and promising potential for next-generation photovoltaics. In this paper, we show that the absorption enhancement in vertical nanowire arrays on a perfectly electric conductor can be further improved through tilting. Vertical nanowire arrays have a 66.2% improvement in ultimate efficiency over an ideal double-pass thin film of the equivalent amount of material. Tilted nanowire arrays, with the same amount of material, exhibit improved performance over vertical nanowire arrays across a broad range of tilt angles (from 38° to 72°). The optimum tilt of 53° has an improvement of 8.6% over that of vertical nanowire arrays and 80.4% over that of the ideal double-pass thin film. Tilted nanowire arrays exhibit improved absorption over the solar spectrum compared with vertical nanowires since the tilt allows for the excitation of additional modes besides the HE 1m modes that are excited at normal incidence. We also observed that tilted nanowire arrays have improved performance over vertical nanowire arrays for a large range of incidence angles (under about 60°).

  6. Evaluation of tilted cone-beam CT orbits in the development of a dedicated hybrid mammotomograph

    International Nuclear Information System (INIS)

    Madhav, P; Crotty, D J; Tornai, M P; McKinley, R L

    2009-01-01

    A compact dedicated 3D breast SPECT-CT (mammotomography) system is currently under development. In its initial prototype, the cone-beam CT sub-system is restricted to a fixed-tilt circular rotation around the patient's pendant breast. This study evaluated stationary-tilt angles for the CT sub-system that will enable maximal volumetric sampling and viewing of the breast and chest wall. Images of geometric/anthropomorphic phantoms were acquired using various fixed-tilt circular and 3D sinusoidal trajectories. The iteratively reconstructed images showed more distortion and attenuation coefficient inaccuracy from tilted cone-beam orbits than from the complex trajectory. Additionally, line profiles illustrated cupping artifacts in planes distal to the central plane of the tilted cone-beam, otherwise not apparent for images acquired with complex trajectories. This indicates that undersampled cone-beam data may be an additional cause of cupping artifacts. High-frequency objects could be distinguished for all trajectories, but their shapes and locations were corrupted by out-of-plane frequency information. Although more acrylic balls were visualized with a fixed-tilt and nearly flat cone-beam at the posterior of the breast, 3D complex trajectories have less distortion and more complete sampling throughout the reconstruction volume. While complex trajectories would ideally be preferred, negatively fixed-tilt source-detector configuration demonstrates minimally distorted patient images.

  7. Do tilt-in-space wheelchairs increase occupational engagement: a critical literature review.

    Science.gov (United States)

    Harrand, Jenny; Bannigan, Katrina

    2016-01-01

    A wheelchair can enhance the quality of life of an individual with limited mobility, poor trunk control and stability, by enabling activity and participation and so occupational engagement. High specification wheelchairs which can tilt-in-space enable the position of users to be altered to suit activity and context. Despite tilt-in-space wheelchairs being expensive little is known about their therapeutic value. A critical literature review of the evidence was undertaken to evaluate whether the use of tilt-in-space increases occupational engagement. A wide ranging search strategy identified 170 articles which were screened using inclusion criteria. The eligible literature (n = 6) was analysed thematically using open coding. The majority of the participants used tilt-in-space but the data was too heterogeneous to combine. Measures of occupational engagement were not used so the therapeutic value could not be assessed. There is a lack of high quality evidence about the therapeutic benefits of tilt-in-space wheelchairs. Given the expense associated with providing these wheelchairs, and the increase in their provision, research is needed to justify provision of high specification wheelchairs to meet the occupational needs of users within the limited resources of health and social care. Implications for Rehabilitation Tilt-in-space wheelchairs. Wheelchairs are an important and essential assistive device for promoting independence and function. Suggests there are benefits for tilt-in-space wheelchairs. Identifies the need for additional large scale research.

  8. Research on Method of Photoelectric Measurement for Tilt Angle of Scanning Mirror of Infrared Earth Sensor

    International Nuclear Information System (INIS)

    Xu, X P; Zhang, G Y; Zhang, N; Wang, L Y

    2006-01-01

    Tilt angle of scanning mirror is one of the important qualifications of performance measurement on the earth surface for swing scanning mode infrared the earth sensor. In order to settle the problem of measuring the tilt angle of scanning mirror in dynamic, real-time and non-contact, based on laser inspecting technology and CCD probing technology, a method of laser dynamical measurement for tilt angle of scanning mirror of the infrared earth sensor is presented. The measurement system developed in this paper can accomplish the dynamic and static laser non-contact measurement for the parameters of scanning mirror such as tilt angle, swing frequency, etc. In this paper the composition and overall structure of system are introduced. Emphasis on analyzing and discussing the theory of dynamically measuring tilt angle of scanning mirror, the problems of data processing and error correction are settled by established mathematic model of system. The accuracy of measurement system is verified by experiment, the results indicated that measurement range of system for tilt angle is 0∼±12 0 , accuracy of dynamic and static measurement is less than ±0.05 0 , this method of dynamically measuring tilt angle is suitable

  9. RE-EXAMINING SUNSPOT TILT ANGLE TO INCLUDE ANTI-HALE STATISTICS

    Energy Technology Data Exchange (ETDEWEB)

    McClintock, B. H. [University of Southern Queensland, Toowoomba, 4350 (Australia); Norton, A. A. [HEPL, Stanford University, Palo Alto, CA 94305 (United States); Li, J., E-mail: u1049686@umail.usq.edu.au, E-mail: aanorton@stanford.edu, E-mail: jli@igpp.ucla.edu [Department of Earth, Planetary, and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095 (United States)

    2014-12-20

    Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974-2014 that determined sunspot tilt angles from daily white light observations, and data provided by Li and Ulrich that determined sunspot magnetic tilt angle using Mount Wilson magnetograms from 1974-2012. The magnetograms allowed for BMR tilt angles that were anti-Hale in configuration, so tilt values ranged from 0 to 360° rather than the more common ±90°. We explore the visual representation of magnetic tilt angles on a traditional butterfly diagram by plotting the mean area-weighted latitude of umbral activity in each bipolar sunspot group, including tilt information. The large scatter of tilt angles over the course of a single cycle and hemisphere prevents Joy's law from being visually identified in the tilt-butterfly diagram without further binning. The average latitude of anti-Hale regions does not differ from the average latitude of all regions in both hemispheres. The distribution of anti-Hale sunspot tilt angles are broadly distributed between 0 and 360° with a weak preference for east-west alignment 180° from their expected Joy's law angle. The anti-Hale sunspots display a log-normal size distribution similar to that of all sunspots, indicating no preferred size for anti-Hale sunspots. We report that 8.4% ± 0.8% of all bipolar sunspot regions are misclassified as Hale in traditional catalogs. This percentage is slightly higher for groups within 5° of the equator due to the misalignment of the magnetic and heliographic equators.

  10. RE-EXAMINING SUNSPOT TILT ANGLE TO INCLUDE ANTI-HALE STATISTICS

    International Nuclear Information System (INIS)

    McClintock, B. H.; Norton, A. A.; Li, J.

    2014-01-01

    Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974-2014 that determined sunspot tilt angles from daily white light observations, and data provided by Li and Ulrich that determined sunspot magnetic tilt angle using Mount Wilson magnetograms from 1974-2012. The magnetograms allowed for BMR tilt angles that were anti-Hale in configuration, so tilt values ranged from 0 to 360° rather than the more common ±90°. We explore the visual representation of magnetic tilt angles on a traditional butterfly diagram by plotting the mean area-weighted latitude of umbral activity in each bipolar sunspot group, including tilt information. The large scatter of tilt angles over the course of a single cycle and hemisphere prevents Joy's law from being visually identified in the tilt-butterfly diagram without further binning. The average latitude of anti-Hale regions does not differ from the average latitude of all regions in both hemispheres. The distribution of anti-Hale sunspot tilt angles are broadly distributed between 0 and 360° with a weak preference for east-west alignment 180° from their expected Joy's law angle. The anti-Hale sunspots display a log-normal size distribution similar to that of all sunspots, indicating no preferred size for anti-Hale sunspots. We report that 8.4% ± 0.8% of all bipolar sunspot regions are misclassified as Hale in traditional catalogs. This percentage is slightly higher for groups within 5° of the equator due to the misalignment of the magnetic and heliographic equators

  11. Combined Influence of Visual Scene and Body Tilt on Arm Pointing Movements: Gravity Matters!

    Science.gov (United States)

    Scotto Di Cesare, Cécile; Sarlegna, Fabrice R.; Bourdin, Christophe; Mestre, Daniel R.; Bringoux, Lionel

    2014-01-01

    Performing accurate actions such as goal-directed arm movements requires taking into account visual and body orientation cues to localize the target in space and produce appropriate reaching motor commands. We experimentally tilted the body and/or the visual scene to investigate how visual and body orientation cues are combined for the control of unseen arm movements. Subjects were asked to point toward a visual target using an upward movement during slow body and/or visual scene tilts. When the scene was tilted, final pointing errors varied as a function of the direction of the scene tilt (forward or backward). Actual forward body tilt resulted in systematic target undershoots, suggesting that the brain may have overcompensated for the biomechanical movement facilitation arising from body tilt. Combined body and visual scene tilts also affected final pointing errors according to the orientation of the visual scene. The data were further analysed using either a body-centered or a gravity-centered reference frame to encode visual scene orientation with simple additive models (i.e., ‘combined’ tilts equal to the sum of ‘single’ tilts). We found that the body-centered model could account only for some of the data regarding kinematic parameters and final errors. In contrast, the gravity-centered modeling in which the body and visual scene orientations were referred to vertical could explain all of these data. Therefore, our findings suggest that the brain uses gravity, thanks to its invariant properties, as a reference for the combination of visual and non-visual cues. PMID:24925371

  12. Effects of Frequency and Motion Paradigm on Perception of Tilt and Translation During Periodic Linear Acceleration

    Science.gov (United States)

    Beaton, K. H.; Holly, J. E.; Clement, G. R.; Wood, Scott J.

    2009-01-01

    Previous studies have demonstrated an effect of frequency on the gain of tilt and translation perception. Results from different motion paradigms are often combined to extend the stimulus frequency range. For example, Off-Vertical Axis Rotation (OVAR) and Variable Radius Centrifugation (VRC) are useful to test low frequencies of linear acceleration at amplitudes that would require impractical sled lengths. The purpose of this study was to compare roll-tilt and lateral translation motion perception in 12 healthy subjects across four paradigms: OVAR, VRC, sled translation and rotation about an earth-horizontal axis. Subjects were oscillated in darkness at six frequencies from 0.01875 to 0.6 Hz (peak acceleration equivalent to 10 deg, less for sled motion below 0.15 Hz). Subjects verbally described the amplitude of perceived tilt and translation, and used a joystick to indicate the direction of motion. Consistent with previous reports, tilt perception gain decreased as a function of stimulus frequency in the motion paradigms without concordant canal tilt cues (OVAR, VRC and Sled). Translation perception gain was negligible at low stimulus frequencies and increased at higher frequencies. There were no significant differences between the phase of tilt and translation, nor did the phase significantly vary across stimulus frequency. There were differences in perception gain across the different paradigms. Paradigms that included actual tilt stimuli had the larger tilt gains, and paradigms that included actual translation stimuli had larger translation gains. In addition, the frequency at which there was a crossover of tilt and translation gains appeared to vary across motion paradigm between 0.15 and 0.3 Hz. Since the linear acceleration in the head lateral plane was equivalent across paradigms, differences in gain may be attributable to the presence of linear accelerations in orthogonal directions and/or cognitive aspects based on the expected motion paths.

  13. Effects of Vestibular Loss on Orthostatic Responses to Tilts in the Pitch Plane

    Science.gov (United States)

    Wood, Scott J.; Serrador, Jorge M.; Black, F. Owen; Rupert,Angus H.; Schlegel, Todd T.

    2004-01-01

    The purpose of this study was to determine the extent to which vestibular loss might impair orthostatic responses to passive tilts in the pitch plane in human subjects. Data were obtained from six subjects having chronic bilateral vestibular loss and six healthy individuals matched for age, gender, and body mass index. Vestibular loss was assessed with a comprehensive battery including dynamic posturography, vestibulo-ocular and optokinetic reflexes, vestibular evoked myogenic potentials, and ocular counterrolling. Head up tilt tests were conducted using a motorized two-axis table that allowed subjects to be tilted in the pitch plane from either a supine or prone body orientation at a slow rate (8 deg/s). The sessions consisted of three tilts, each consisting of20 min rest in a horizontal position, tilt to 80 deg upright for 10 min, and then return to the horizontal position for 5 min. The tilts were performed in darkness (supine and prone) or in light (supine only). Background music was used to mask auditory orientation cues. Autonomic measurements included beat-to-beat recordings of blood pressure (Finapres), heart rate (ECG), cerebral blood flow velocity in the middle cerebral artery (transcranial Doppler), end tidal CO2, respiratory rate and volume (Respritrace), and stroke volume (impedance cardiography). For both patients and control subjects, cerebral blood flow appeared to exhibit the most rapid adjustment following transient changes in posture. Outside of a greater cerebral hypoperfusion in patients during the later stages of tilt, responses did not differ dramatically between the vestibular loss and control subjects, or between tilts performed in light and dark room conditions. Thus, with the 'exception of cerebrovascular regulation, we conclude that orthostatic responses during slow postural tilts are not substantially impaired in humans following chronic loss of vestibular function, a result that might reflect compensation by nonvisual graviceptor

  14. Quantum carpets in a one-dimensional tilted optical lattices

    Science.gov (United States)

    Parra Murillo, Carlos Alberto; Muã+/-Oz Arias, Manuel Humberto; Madroã+/-Ero, Javier

    A unit filling Bose-Hubbard Hamiltonian embedded in a strong Stark field is studied in the off-resonant regime inhibiting single- and many-particle first-order tunneling resonances. We investigate the occurrence of coherent dipole wavelike propagation along an optical lattice by means of an effective Hamiltonian accounting for second-order tunneling processes. It is shown that dipole wave function evolution in the short-time limit is ballistic and that finite-size effects induce dynamical self-interference patterns known as quantum carpets. We also present the effects of the border right after the first reflection, showing that the wave function diffuses normally with the variance changing linearly in time. This work extends the rich physical phenomenology of tilted one-dimensional lattice systems in a scenario of many interacting quantum particles, the so-called many-body Wannier-Stark system. The authors acknownledge the finantial support of the Universidad del Valle (project CI 7996). C. A. Parra-Murillo greatfully acknowledges the financial support of COLCIENCIAS (Grant 656).

  15. Phonon thermal transport through tilt grain boundaries in strontium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Zexi; Chen, Xiang; Yang, Shengfeng; Xiong, Liming; Chen, Youping [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida 32611 (United States); Deng, Bowen; Chernatynskiy, Aleksandr [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2014-08-21

    In this work, we perform nonequilibrium molecular dynamics simulations to study phonon scattering at two tilt grain boundaries (GBs) in SrTiO{sub 3}. Mode-wise energy transmission coefficients are obtained based on phonon wave-packet dynamics simulations. The Kapitza conductance is then quantified using a lattice dynamics approach. The obtained results of the Kapitza conductance of both GBs compare well with those obtained by the direct method, except for the temperature dependence. Contrary to common belief, the results of this work show that the optical modes in SrTiO{sub 3} contribute significantly to phonon thermal transport, accounting for over 50% of the Kapitza conductance. To understand the effect of the GB structural disorder on phonon transport, we compare the local phonon density of states of the atoms in the GB region with that in the single crystalline grain region. Our results show that the excess vibrational modes introduced by the structural disorder do not have a significant effect on phonon scattering at the GBs, but the absence of certain modes in the GB region appears to be responsible for phonon reflections at GBs. This work has also demonstrated phonon mode conversion and simultaneous generation of new modes. Some of the new modes have the same frequency as the initial wave packet, while some have the same wave vector but lower frequencies.

  16. Gastrointestinal Physiology During Head Down Tilt Bedrest in Human Subjects

    Science.gov (United States)

    Vaksman, Z.; Guthienz, J.; Putcha, L.

    2008-01-01

    Introduction: Gastrointestinal (GI) motility plays a key role in the physiology and function of the GI tract. It directly affects absorption of medications and nutrients taken by mouth, in addition to indirectly altering GI physiology by way of changes in the microfloral composition and biochemistry of the GI tract. Astronauts have reported nausea, loss of appetite and constipation during space flight all of which indicate a reduction in GI motility and function similar to the one seen in chronic bed rest patients. The purpose of this study is to determine GI motility and bacterial proliferation during -6 degree head down tilt bed rest (HTD). Methods: Healthy male and female subjects between the ages of 25-40 participated in a 60 day HTD study protocol. GI transit time (GITT) was determined using lactulose breath hydrogen test and bacterial overgrowth was measured using glucose breath hydrogen test. H. Pylori colonization was determined using C13-urea breath test (UBIT#). All three tests were conducted on 9 days before HDT, and repeated on HDT days 2, 28, 58, and again on day 7 after HDT. Results: GITT increased during HTD compared to the respective ambulatory control values; GITT was significantly lower on day 7 after HTD. A concomitant increase in bacterial colonization was also noticed during HDT starting after approximately 28 days of HDT. However, H. Pylori proliferation was not recorded during HDT as indicated by UBIT#. Conclusion: GITT significantly decreased during HDT with a concomitant increase in the proliferation of GI bacterial flora but not H. pylori.

  17. Ferromagnetism controlled by electric field in tilted phosphorene nanoribbon

    Science.gov (United States)

    Farooq, M. Umar; Hashmi, Arqum; Hong, Jisang

    2016-01-01

    Study on phosphorene nanoribbon was mostly focused on zigzag and armchair structures and no ferromagnetic ground state was observed in these systems. Here, we investigated the magnetic property of tilted black phosphorene nanoribbons (TPNRs) affected by an external electric field. We also studied the edge passivation effect on the magnetism and thermal stability of the nanoribbons. The pure TPNR displayed an edge magnetic state, but it disappeared in the edge reconstructed TPNR due to the self-passivation. In addition, we found that the bare TPNR was mechanically unstable because an imaginary vibration mode was obtained. However, the imaginary vibration mode disappeared in the edge passivated TPNRs. No edge magnetism was observed in hydrogen and fluorine passivated TPRNs. In contrast, the oxygen passivated TPNR was more stable than the pure TPNR and the edge-to-edge antiferromagntic (AFM) ground state was obtained. We found that the magnetic ground state could be tuned by the electric field from antiferromagnetic (AFM) to ferromagnetic (FM) ground state. Interestingly, the oxygen passivated TPNR displayed a half-metallic state at a proper electric field in both FM and AFM states. This finding may provoke an intriguing issue for potential spintronics application using the phosphorene nanoribbons. PMID:27189417

  18. Phonon thermal transport through tilt grain boundaries in strontium titanate

    International Nuclear Information System (INIS)

    Zheng, Zexi; Chen, Xiang; Yang, Shengfeng; Xiong, Liming; Chen, Youping; Deng, Bowen; Chernatynskiy, Aleksandr

    2014-01-01

    In this work, we perform nonequilibrium molecular dynamics simulations to study phonon scattering at two tilt grain boundaries (GBs) in SrTiO 3 . Mode-wise energy transmission coefficients are obtained based on phonon wave-packet dynamics simulations. The Kapitza conductance is then quantified using a lattice dynamics approach. The obtained results of the Kapitza conductance of both GBs compare well with those obtained by the direct method, except for the temperature dependence. Contrary to common belief, the results of this work show that the optical modes in SrTiO 3 contribute significantly to phonon thermal transport, accounting for over 50% of the Kapitza conductance. To understand the effect of the GB structural disorder on phonon transport, we compare the local phonon density of states of the atoms in the GB region with that in the single crystalline grain region. Our results show that the excess vibrational modes introduced by the structural disorder do not have a significant effect on phonon scattering at the GBs, but the absence of certain modes in the GB region appears to be responsible for phonon reflections at GBs. This work has also demonstrated phonon mode conversion and simultaneous generation of new modes. Some of the new modes have the same frequency as the initial wave packet, while some have the same wave vector but lower frequencies

  19. Cyclonic circulation of Saturn's atmosphere due to tilted convection

    Science.gov (United States)

    Afanasyev, Y. D.; Zhang, Y.

    2018-02-01

    Saturn displays cyclonic vortices at its poles and the general atmospheric circulation at other latitudes is dominated by embedded zonal jets that display cyclonic circulation. The abundance of small-scale convective storms suggests that convection plays a role in producing and maintaining Saturn's atmospheric circulation. However, the dynamical influence of small-scale convection on Saturn's general circulation is not well understood. Here we present laboratory analogue experiments and propose that Saturn's cyclonic circulation can be explained by tilted convection in which buoyancy forces do not align with the planet's rotation axis. In our experiments—conducted with a cylindrical water tank that is heated at the bottom, cooled at the top and spun on a rotating table—warm rising plumes and cold sinking water generate small anticyclonic and cyclonic vortices that are qualitatively similar to Saturn's convective storms. Numerical simulations complement the experiments and show that this small-scale convection leads to large-scale cyclonic flow at the surface and anticyclonic circulation at the base of the fluid layer, with a polar vortex forming from the merging of smaller cyclonic storms that are driven polewards.

  20. Tilt-table test: its role in modern practice.

    Science.gov (United States)

    Sandhu, Kulwinder S; Khan, Pervez; Panting, John; Nadar, Sunil

    2013-06-01

    Syncope is a major healthcare problem with significant morbidity, mortality and healthcare cost. It is a common symptom with a complex pathophysiology and, therefore, several aetiologies. Tilt-table testing (TTT) is an important, yet perhaps not widely-used, test that forms part of the management of syncope. We sought to assess the utilisation of this test in our institution for the investigation of patients with syncope, to study the referral patterns and the outcomes and usefulness of the TTT in a real-life setting. We undertook a retrospective study of all the TTT that were performed in our institution between January 2009 and October 2009. Of the 69 patients in which TTT was performed, 14 (20%) presented with presyncope, 24 (35%) with a single episode of syncope and 24 (44%) with multiple episodes. The average age was 57.2 years and 64% were female. Of the total patients, 35 (51%) had an abnormal TTT. Of the patients with normal TTT, four had internal loop recorders and six were referred to other medical specialities. The remaining patients (49%) had no formal diagnosis and were referred back to their general practitioner. TTT remains a common test modality and has great value when undertaken in the correct clinical context. This underlines the importance of a detailed clinical history. The European Society of Cardiology guidelines ensure a methodical and rational approach to syncopal patients and aide in choosing the right patient for the right test.

  1. Tibia Bone Microvascular Flow Dynamics as Compared to Anterior Tibial Artery Flow During Body Tilt.

    Science.gov (United States)

    Becker, Rachel L; Siamwala, Jamila H; Macias, Brandon R; Hargens, Alan R

    2018-04-01

    We compared microvascular and macrovascular blood flows of the tibia and anterior tibial artery during graded whole-body tilt. We hypothesized equal responses for bone microvascular and macrovascular blood flows during varying angles of tilt. There were 18 volunteers who were randomly positioned in the following postures: supine, 15° head-up tilt, 6° head-up tilt, 6° head-down tilt, and 15° head-down tilt using an inversion table with reference to seated posture (baseline control). Ultrasonography quantified anterior tibial arterial diameter and peak systolic velocity, enabling calculation of macrovascular blood flow to the tibia. Tibial bone microvascular blood flow was measured noninvasively using photoplethysmography in the same leg. Transitioning from a seated position to a supine position, macrovascular blood flow did not change significantly (1.81 ± 1.18 to 2.80 ± 1.74cm 3 · s-1). However, bone microvascular flow increased significantly (0.36 ± 0.23 to 1.11 ± 0.79 V) from the seated to the supine position. Transitioning from a seated posture to 15° head-down tilt, both arterial macrovascular and bone microvascular flows increased significantly (1.81 ± 1.18 to 3.32 ± 2.08 cm3 · s-1 and 0.36 ± 0.23 V to 2.99 ± 2.71 V, respectively). The normalized flow for microvascular blood flow as a function of body tilt was significantly greater than that for macrovascular blood flow at 6° and 15° head-down tilt. These data do not support our hypothesis that bone microvascular flow and arterial macrovascular flow share equal responses to altered body tilt. Therefore, for a given decrease in local blood pressure in the leg with head-down body tilt, the magnitude of increase in blood flow is greater in the microcirculation as compared to the feeding artery.Becker RL, Siamwala JH, Macias BR, Hargens AR. Tibia bone microvascular flow dynamics as compared to anterior tibial artery flow during body tilt. Aerosp Med Hum Perform. 2018; 89(4):357-364.

  2. The importance of prostate bed tilt during postprostatectomy intensity-modulated radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Linda J., E-mail: Linda.Bell1@health.nsw.gov.au [Northern Sydney Cancer Centre, Radiation Oncology Department, Royal North Shore Hospital, St Leonards, New South Wales (Australia); Faculty of Health Sciences, University of Sydney, Lidcombe, New South Wales (Australia); Cox, Jennifer [Northern Sydney Cancer Centre, Radiation Oncology Department, Royal North Shore Hospital, St Leonards, New South Wales (Australia); Faculty of Health Sciences, University of Sydney, Lidcombe, New South Wales (Australia); Eade, Thomas; Rinks, Marianne; Kneebone, Andrew [Northern Sydney Cancer Centre, Radiation Oncology Department, Royal North Shore Hospital, St Leonards, New South Wales (Australia)

    2014-10-01

    Variations in rectal and bladder filling can create a tilt of the prostate bed, which generates the potential for a geographic miss during postprostatectomy radiotherapy. The aim of this study is to assess the effect that bladder and rectum filling has on planning target volume angle, to determine a method to assess prostate bed tilt leading to potential geographic miss, and to discuss possible implementation issues. The cone-beam computed tomography images (n = 377) of 40 patients who received postprostatectomy radiotherapy with intensity-modulated radiotherapy were reviewed. The amount of tilt in the prostate bed was defined as the angle change between 2 surgical clips, one in the upper prostate bed and another in the lower. A potential geographic miss was defined as movement of any clip of more than 1 cm in any direction or 0.5 cm posteriorly when aligned to bone anatomy. Variations in bladder and rectum size were correlated with the degree of prostate bed tilt, and the rate of potential geographic miss was determined. A possible clinical use of prostate bed tilt was then assessed for different imaging techniques. A tilt of more than 10° was seen in 20.2% of images, which resulted in a 57.9% geographic miss rate of the superior clip. When tilt remained within 10°, there was only a 9% rate of geographic miss. Potential geographic miss of the inferior surgical clip was rare, occurring in only 1.9% of all images reviewed. The most common occurrence when the prostate bed tilt increased by more than 10° was a smaller bladder and larger rectum (6.4% of all images). The most common occurrence when the prostate bed tilt decreased by more than 10° was a larger bladder and smaller rectum (1.3% of all images). Significant prostate bed tilt (>± 10°) occurred in more than 20% of images, creating a 58% rate of geographic miss. Greatest prostate bed tilt occurred when the bladder size increased or reduced by more than 2 cm or the superior rectum size increased by more

  3. Analysis of fixed tilt and sun tracking photovoltaic–micro wind based hybrid power systems

    International Nuclear Information System (INIS)

    Sinha, Sunanda; Chandel, S.S.

    2016-01-01

    Graphical abstract: 6 kW p photovoltaic–micro wind based hybrid power system analysis in a Indian Western Himalayan location. - Highlights: • Power generation by a roof mounted photovoltaic–micro wind hybrid system is explored. • Optimum hybrid configurations using fixed and sun tracking photovoltaic systems are determined. • Analysis of hybrid systems with optimally tilted and different sun tracking systems is presented. • Two axis sun tracking systems are found to generate 4.88–26.29% more energy than fixed tilt system. • Hybrid system installed at optimum tilt angle is found to be cost effective than a sun tracking system. - Abstract: In this study fixed tilt and sun tracking photovoltaic based micro wind hybrid power systems are analyzed along with determining the optimum configurations for a 6 kW p roof mounted micro wind based hybrid system using fixed and tracking photovoltaic systems to enhance the power generation potential in a low windy Indian hilly terrain with good solar resource. The main objective of the study is to enhance power generation by focusing on photovoltaic component of the hybrid system. A comparative power generation analysis of different configurations of hybrid systems with fixed tilt, monthly optimum tilt, yearly optimum tilt and 6 different sun tracking photovoltaic systems is carried out using Hybrid Optimization Model for Electric Renewables. Monthly and seasonal optimum tilt angles determined for the location vary between 0° and 60° with annual optimum tilt angle as 29.25°. The optimum configurations for all sun tracking systems except for the two axis tracking system is found to be 7 kW p photovoltaic system, one 5 kW p wind turbine, 10 batteries and a 2 kW p inverter. The optimum configuration for two axis tracking system and two types of fixed tilt systems, is found to be a 8 kW p photovoltaic system, one 5 kW p wind turbine, 10 batteries and a 2 kW p inverter. The results show that horizontal axis with

  4. Modulation of internal estimates of gravity during and after prolonged roll-tilts.

    Directory of Open Access Journals (Sweden)

    Alexander A Tarnutzer

    Full Text Available Perceived direction of gravity, as assessed by the subjective visual vertical (SVV, shows roll-angle dependent errors that drift over time and a bias upon return to upright. According to Bayesian observer theory, the estimated direction of gravity is derived from the posterior probability distribution by combining sensory input and prior knowledge about earth-vertical in a statistically optimal fashion. Here we aimed to further characterize the stability of SVV during and after prolonged roll-tilts. Specifically we asked whether the post-tilt bias is related to the drift pattern while roll-tilted. Twenty-nine healthy human subjects (23-56 yo repetitively adjusted a luminous arrow to the SVV over periods of 5 min while upright, roll-tilted (± 45°, ± 90°, and immediately after returning to upright. Significant (p<0.05 drifts (median absolute drift-amplitude: 10°/5 min were found in 71% (± 45° and 78% (± 90° of runs. At ± 90° roll-tilt significant increases in absolute adjustment errors were more likely (76%, whereas significant increases (56% and decreases (44% were about equally frequent at ± 45°. When returning to upright, an initial bias towards the previous roll-position followed by significant exponential decay (median time-constant: 71 sec was noted in 47% of all runs (all subjects pooled. No significant correlations were found between the drift pattern during and immediately after prolonged roll-tilt. We conclude that the SVV is not stable during and after prolonged roll-tilt and that the direction and magnitude of drift are individually distinct and roll-angle-dependent. Likely sensory and central adaptation and random-walk processes contribute to drift while roll-tilted. Lack of correlation between the drift and the post-tilt bias suggests that it is not the inaccuracy of the SVV estimate while tilted that determines post-tilt bias, but rather the previous head-roll orientation relative to gravity. We therefore favor central

  5. Conceptual design study of 1985 commercial tilt rotor transports. Volume 3. STOL design summary. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sambell, K.W.

    1976-04-01

    A conceptual design study is presented of 1,985 commercial tilt rotor STOL transports for a NASA 200 n. mi. (370 km) STOL Mission. A 100-passenger STOL Variant (Bell D313) of the Phase I VTOL Tilt Rotor Aircraft is defined. Aircraft characteristics are given; with the aircraft redesigned to meet 2,000-foot (610 m) field criteria, with emphasis on low fuel consumption and low direct operating cost. The 100-passenger STOL Tilt Rotor Aircraft was analyzed for performance, weights, economics, handling qualities, noise footprint and aeroelastic stability. (GRA)

  6. Does osteoporosis reduce the primary tilting stability of cementless acetabular cups?

    Science.gov (United States)

    von Schulze Pellengahr, Christoph; von Engelhardt, Lars V; Wegener, Bernd; Müller, Peter E; Fottner, Andreas; Weber, Patrick; Ackermann, Ole; Lahner, Matthias; Teske, Wolfram

    2015-04-21

    Cementless hip cups need sufficient primary tilting stability to achieve osseointegration. The aim of the study was to assess differences of the primary implant stability in osteoporotic bone and in bone with normal bone density. To assess the influence of different cup designs, two types of threaded and two types of press-fit cups were tested. The maximum tilting moment for two different cementless threaded cups and two different cementless press-fit cups was determined in macerated human hip acetabuli with reduced (n=20) and normal bone density (n=20), determined using Q-CT. The tilting moments for each cup were determined five times in the group with reduced bone density and five times in the group with normal bone density, and the respective average values were calculated. The mean maximum extrusion force of the threaded cup Zintra was 5670.5 N (max. tilting moment 141.8 Nm) in bone with normal density and.5748.3 N (max. tilting moment 143.7 Nm) in osteoporotic bone. For the Hofer Imhof (HI) threaded cup it was 7681.5 N (192.0 Nm) in bone with normal density and 6828.9 N (max. tilting moment 170.7 Nm) in the group with osteoporotic bone. The mean maximum extrusion force of the macro-textured press-fit cup Metallsockel CL was 3824.6 N (max. tilting moment 95.6 Nm) in bone with normal and 2246.2 N (max. tilting moment 56.2 Nm) in osteoporotic bone. For the Monoblock it was 1303.8 N (max. tilting moment 32.6 Nm) in normal and 1317 N (max. tilting moment 32.9 Nm) in osteoporotic bone. There was no significance. A reduction of the maximum tilting moment in osteoporotic bone of the ESKA press-fit cup Metallsockel CL was noticed. Results on macerated bone specimens showed no statistically significant reduction of the maximum tilting moment in specimens with osteoporotic bone density compared to normal bone, neither for threaded nor for the press-fit cups. With the limitation that the results were obtained using macerated bone, we could not detect any restrictions for

  7. Modulation of Internal Estimates of Gravity during and after Prolonged Roll-Tilts

    Science.gov (United States)

    Tarnutzer, Alexander A.; Bertolini, Giovanni; Bockisch, Christopher J.; Straumann, Dominik; Marti, Sarah

    2013-01-01

    Perceived direction of gravity, as assessed by the subjective visual vertical (SVV), shows roll-angle dependent errors that drift over time and a bias upon return to upright. According to Bayesian observer theory, the estimated direction of gravity is derived from the posterior probability distribution by combining sensory input and prior knowledge about earth-vertical in a statistically optimal fashion. Here we aimed to further characterize the stability of SVV during and after prolonged roll-tilts. Specifically we asked whether the post-tilt bias is related to the drift pattern while roll-tilted. Twenty-nine healthy human subjects (23-56yo) repetitively adjusted a luminous arrow to the SVV over periods of 5min while upright, roll-tilted (±45°, ±90°), and immediately after returning to upright. Significant (p<0.05) drifts (median absolute drift-amplitude: 10°/5min) were found in 71% (±45°) and 78% (±90°) of runs. At ±90° roll-tilt significant increases in absolute adjustment errors were more likely (76%), whereas significant increases (56%) and decreases (44%) were about equally frequent at ±45°. When returning to upright, an initial bias towards the previous roll-position followed by significant exponential decay (median time-constant: 71sec) was noted in 47% of all runs (all subjects pooled). No significant correlations were found between the drift pattern during and immediately after prolonged roll-tilt. We conclude that the SVV is not stable during and after prolonged roll-tilt and that the direction and magnitude of drift are individually distinct and roll-angle-dependent. Likely sensory and central adaptation and random-walk processes contribute to drift while roll-tilted. Lack of correlation between the drift and the post-tilt bias suggests that it is not the inaccuracy of the SVV estimate while tilted that determines post-tilt bias, but rather the previous head-roll orientation relative to gravity. We therefore favor central adaptation, most

  8. DYNAMIC ANALYSIS OF HYDRAULIC DRIVE OF TILTING PLATFORM MECHANISM OF DUMP TRUCK

    Directory of Open Access Journals (Sweden)

    P. Kishkevich

    2011-01-01

    Full Text Available Object of research – hydraulic drive of tilting platform mechanism of dump truck. We pro-pose a dynamic model of the hydraulic system. The model takes into account the cyclic operation (lifting, lowering the platform.

  9. DYNAMIC ANALYSIS OF HYDRAULIC DRIVE OF TILTING PLATFORM MECHANISM OF DUMP TRUCK

    OpenAIRE

    P. Kishkevich; A. Safonau; I. Selivonchik; P. Bartosh

    2011-01-01

    Object of research – hydraulic drive of tilting platform mechanism of dump truck. We pro-pose a dynamic model of the hydraulic system. The model takes into account the cyclic operation (lifting, lowering the platform).

  10. Experimental study on the effect of heat flux tilt on rod bundle dryout limitation

    International Nuclear Information System (INIS)

    Sugawara, S.; Terunuma, K.; Kamoshida, H.

    1995-01-01

    The effect of heat flux tilt on rod bundle dryout limitation was studied experimentally using a full-scale mock-up test facility and simulated 36-rod fuel bundles in which heater pins have azimuthal nonuniform heat flux distribution (i.e., heat flux tilt). Experimental results for typical lateral power distribution in the bundle indicate that the bundle dryout power with azimuthal heat flux tilt is higher than that without azimuthal heat flux tilt in the entire experimental range. Consequently, it is concluded that the dryout experiment using the test bundle with heater pins which has circumferentially uniform heat flux distribution gives conservative results for the usual lateral power distribution in a bundle in which the relative power of outermost-circle fuel rods is higher than those of middle- and inner-circle ones. (author). 15 refs., 2 tabs., 8 figs

  11. Tilt meters for the Alignment System of the CMS Experiment: Users Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E.; Ferrando, A.; Josa, M.I.; Molinero, A.; Navarrete, J.; Oller, J.C.; Yuste, C.

    2007-09-27

    We present the instructions for the use of the electrolytic tilt meters installed in the link alignments system of the CMS experimental and give the Data Base to be used as a Handbook during CMS operation. (Author) 16 refs.

  12. Thermal insensitive optical liquid level sensor based on excessively tilted fibre Bragg grating

    OpenAIRE

    Mou, Chengbo; Zhou, Kaiming; Zhang, Lin; Bennion, Ian

    2008-01-01

    We demonstrate a liquid level sensor based on the surrounding medium refractive index (SRI) sensing using of an excessively tilted fibre Bragg grating (ETFBG). The sensor has low thermal cross sensitivity and high SRI responsivity.

  13. Tilt aftereffects in a self-organizing model of the primary visual cortex.

    Science.gov (United States)

    Bednar, J A; Miikkulainen, R

    2000-07-01

    RF-LISSOM, a self-organizing model of laterally connected orientation maps in the primary visual cortex, was used to study the psychological phenomenon known as the tilt aftereffect. The same self-organizing processes that are responsible for the long-term development of the map are shown to result in tilt aftereffects over short timescales in the adult. The model permits simultaneous observation of large numbers of neurons and connections, making it possible to relate high-level phenomena to low-level events, which is difficult to do experimentally. The results give detailed computational support for the long-standing conjecture that the direct tilt aftereffect arises from adaptive lateral interactions between feature detectors. They also make a new prediction that the indirect effect results from the normalization of synaptic efficacies during this process. The model thus provides a unified computational explanation of self-organization and both the direct and indirect tilt aftereffect in the primary visual cortex.

  14. Experimental confirmation of the atomic force microscope cantilever stiffness tilt correction

    Science.gov (United States)

    Gates, Richard S.

    2017-12-01

    The tilt angle (angle of repose) of an AFM cantilever relative to the surface it is interrogating affects the effective stiffness of the cantilever as it analyzes the surface. For typical AFMs and cantilevers that incline from 10° to 15° tilt, this is thought to be a 3%-7% stiffness increase correction. While the theoretical geometric analysis of this effect may have reached a consensus that it varies with cos-2 θ, there is very little experimental evidence to confirm this using AFM cantilevers. Recently, the laser Doppler vibrometry thermal calibration method utilized at NIST has demonstrated sufficient stiffness calibration accuracy, and precision to allow a definitive experimental confirmation of the particular trigonometric form of this tilt effect using a commercial microfabricated AFM cantilever specially modified to allow strongly tilted (up to 15°) effective cantilever stiffness measurements.

  15. High Speed Rail Tilt Train Technology : A State of the Art Survey

    Science.gov (United States)

    1992-06-01

    This report presents an assessment of the technical and operational features of existing and proposed tilt-body rail passenger vehicles. Basic concepts of railroad route selection, track geometry, and curve negotiation are reviewed, and the rationale...

  16. Reducing friction in tilting-pad bearings by the use of enclosed recesses

    DEFF Research Database (Denmark)

    Heinrichson, Niels; Santos, Ilmar

    2008-01-01

    A three-dimensional thermoelastohydrodynamic model is applied to the analysis of tilting-pad bearings with spherical pivots and equipped with deep recesses in the high-pressure regions. A potential for a 10-20% reduction in the friction loss compared to conventional plain bearing pads is documented....... Design suggestions minimizing the power loss are given for various length-to-width ratios. The tilting angle in the sliding direction is more sensitive to correct positioning of the pivot point than conventional bearing pads. Improving the performance by equipping a tilting-pad bearing with a deep recess...... therefore requires accurate analysis and design of the bearing. Similarly, a high sensitivity perpendicular to the sliding direction suggests that this method of reducing friction is more feasible when using line pivots or spring beds than when using spherical pivots for controlling the tilting angle....

  17. Process, Design and Materials for Unidirectionally Tilted Polymeric Micro/Nanohairs and Their Adhesion Characteristics

    Directory of Open Access Journals (Sweden)

    Hyeon Seong Im

    2016-09-01

    Full Text Available Recent research in the field of gecko-inspired dry adhesive has focused on modifying the material and structural properties of polymer-based nanohairs. Polymers such as polystyrene (PS, high-density polyethylene (HDPE, ultraviolet curable epoxy (SU-8, polyurethane acrylate (PUA, polycarbonate (PC, and polydimethyl siloxane (PDMS can fulfill many mechanical property requirements, are easily tunable, and can be produced via large-scale fabrication. However, the fabrication process for tilted structure remains challenging. The tilted structure is a crucial factor in high-degree conformal contact, which facilitates high adhesion, low effective modulus, and directional adhesion properties. Recent studies have attempted to create a tilted structure by applying beam irradiation, mechanical and thermal stress, and magnetic fields. This review provides a comprehensive investigation into advanced strategies for producing tilted polymeric nanostructures and their potential applications in the near future.

  18. Experimental Results of Network-Assisted Interference Suppression Scheme Using Adaptive Beam-Tilt Switching

    Directory of Open Access Journals (Sweden)

    Tomoki Murakami

    2017-01-01

    Full Text Available This paper introduces a network-assisted interference suppression scheme using beam-tilt switching per frame for wireless local area network systems and its effectiveness in an actual indoor environment. In the proposed scheme, two access points simultaneously transmit to their own desired station by adjusting angle of beam-tilt including transmit power assisted from network server for the improvement of system throughput. In the conventional researches, it is widely known that beam-tilt is effective for ICI suppression in the outdoor scenario. However, the indoor effectiveness of beam-tilt for ICI suppression has not yet been indicated from the experimental evaluation. Thus, this paper indicates the effectiveness of the proposed scheme by analyzing multiple-input multiple-output channel matrices from experimental measurements in an office environment. The experimental results clearly show that the proposed scheme offers higher system throughput than the conventional scheme using just transmit power control.

  19. Tilted plane Feldkamp type reconstruction algorithm for spiral cone beam CT

    International Nuclear Information System (INIS)

    Yan Ming; Zhang Cishen

    2005-01-01

    An approximate image reconstruction method for spiral cone beam computed tomography (CT), called tilted plane Feldkamp type reconstruction algorithm (TPFR), is presented in this paper, which extends Feldkamp cone beam reconstruction algorithm to deal with its inaccuracy and artifact problems caused by large cone angle. This is done by tilting the reconstructing planes to minimize the cone angle and optimally fit the spiral segment of the source. The tilted plane image reconstruction requires reforming the three-dimensional projection data set for the tilted plane and application of Feldkamp algorithm to the reformed data set. Analytical and computational results can show that the image reconstruction performance of the proposed TPFR algorithm is superior to that of the Feldkamp reconstruction algorithm in the image quality, volume coverage speed, maximum achievable pitch value, and slice sensitivity profiles. Moreover, it provides more accurate image reconstruction than the existing two-dimensional reconstruction algorithms

  20. Optimization of tilt angle for solar panel: Case study for Madinah, Saudi Arabia

    International Nuclear Information System (INIS)

    Benghanem, M.

    2011-01-01

    This article analyzes the optimal choice of the tilt angle for the solar panel in order to collect the maximum solar irradiation. In this paper, the collector surface is assumed to be facing toward equator. The study is based upon the measured values of daily global and diffuse solar radiation on a horizontal surface. It is shown that the optimal angle of tilt (β opt ) for each month, allows us to collected the maximum solar energy for Madinah site. Annual optimum tilt angle is found to be approximately equal to latitude of the location. It is found that the loss in the amount of collected energy when using the yearly average fixed angle is around 8% compared with the monthly optimum tilt β opt .

  1. Tilt meters for the Alignment System of the CMS Experiment: Users Handbook

    International Nuclear Information System (INIS)

    Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E.; Ferrando, A.; Josa, M.I.; Molinero, A.; Navarrete, J.; Oller, J.C.; Yuste, C.

    2007-01-01

    We present the instructions for the use of the electrolytic tilt meters installed in the link alignments system of the CMS experimental and give the Data Base to be used as a Handbook during CMS operation. (Author) 16 refs

  2. Integrated polymer polarization rotator based on tilted laser ablation

    Science.gov (United States)

    Poulopoulos, Giannis; Kalavrouziotis, Dimitrios; Missinne, Jeroen; Bosman, Erwin; Van Steenberge, Geert; Apostolopoulos, Dimitrios; Avramopoulos, Hercules

    2017-02-01

    sidewalls, employing the tilted laser ablation technology, currently available at CMST. Therefore, the aforementioned simulation steps adhere fully to the respective design rules, taking into account the anticipated fabrication variations

  3. Forward dynamics simulation of human body under tilting perturbations

    Science.gov (United States)

    Naderi, D.; Pasha Zanoosi, A. A.; Sadeghi-Mehr, M.

    2012-02-01

    Human body uses different strategies to maintain its stability and these strategies vary from fixed-foot strategies to strategies which foot is moved in order to increase the support base. Tilting movement of foot is one type of the perturbations usually is exposed to human body. In the presence of such perturbations human body must employ appropriate reactions to prevent threats like falling. But it is not clear that how human body maintains its stability by central nervous system (CNS). At present study it is tried that by presenting a musculoskeletal model of human lower extremity with four links, three degrees of freedom (DOF) and eight skeletal muscles, the level of muscle activations causes the maintenance of stability, be investigated. Using forward dynamics solution, leads to a more general problem, rather than inverse dynamics. Hence, forward dynamics solution by forward optimization has been used for solving this highly nonlinear problem. To this end, first the system's equations of motion has been derived using lagrangian dynamics. Eight Hill-type muscles as actuators of the system were modeled. Because determination of muscle forces considering their number is an undetermined problem, optimization of an appropriate goal function should be practiced. For optimization problem, the characteristics of genetic algorithms as a method based on direct search, and the direct collocation method, has been profited. Also by considering requirements of problem, some constraints such as conservation of model stability are entered into optimization procedure. Finally to investigate validation of model, the results from optimization and experimental data are compared and good agreements are obtained.

  4. Component level study of an actively lubricated LEG Tilting Pad Bearing: Theory and experiment

    DEFF Research Database (Denmark)

    Cerda Varela, Alejandro Javier; Santos, Ilmar Ferreira

    2018-01-01

    This article constitutes the second step in a research effort aiming at evaluating the feasibility of introducing active characteristics into standard leading edge groove (LEG) tilting pad journal bearings. The strategy proposed is to control the LEG inlet flow using a servovalve. This work...... bearing design, validate the available simulation tool and exemplify on a conceptual level the operational benefits from introducing this technology into standard LEG Tilting Pad Bearings....

  5. Tilt stability in nonlinear programming under Mangasarian-Fromovitz constraint qualification

    Czech Academy of Sciences Publication Activity Database

    Mordukhovich, B. S.; Outrata, Jiří

    2013-01-01

    Roč. 49, č. 3 (2013), s. 446-464 ISSN 0023-5954 R&D Projects: GA ČR(CZ) GAP201/12/0671 Institutional support: RVO:67985556 Keywords : variational analysis * second-order theory * generalized differentiation * tilt stability Subject RIV: BA - General Mathematics Impact factor: 0.563, year: 2013 http://library.utia.cas.cz/separaty/2013/MTR/outrata-tilt stability in nonlinear programming under mangasarian-fromovitz constraint qualification.pdf

  6. Motion Perception and Manual Control Performance During Passive Tilt and Translation Following Space Flight

    Science.gov (United States)

    Clement, Gilles; Wood, Scott J.

    2010-01-01

    This joint ESA-NASA study is examining changes in motion perception following Space Shuttle flights and the operational implications of post-flight tilt-translation ambiguity for manual control performance. Vibrotactile feedback of tilt orientation is also being evaluated as a countermeasure to improve performance during a closed-loop nulling task. METHODS. Data has been collected on 5 astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation (216 deg/s) combined with body translation (12-22 cm, peak-to-peak) is utilized to elicit roll-tilt perception (equivalent to 20 deg, peak-to-peak). A forward-backward moving sled (24-390 cm, peak-to-peak) with or without chair tilting in pitch is utilized to elicit pitch tilt perception (equivalent to 20 deg, peak-to-peak). These combinations are elicited at 0.15, 0.3, and 0.6 Hz for evaluating the effect of motion frequency on tilt-translation ambiguity. In both devices, a closed-loop nulling task is also performed during pseudorandom motion with and without vibrotactile feedback of tilt. All tests are performed in complete darkness. PRELIMINARY RESULTS. Data collection is currently ongoing. Results to date suggest there is a trend for translation motion perception to be increased at the low and medium frequencies on landing day compared to pre-flight. Manual control performance is improved with vibrotactile feedback. DISCUSSION. The results of this study indicate that post-flight recovery of motion perception and manual control performance is complete within 8 days following short-duration space missions. Vibrotactile feedback of tilt improves manual control performance both before and after flight.

  7. Analysis of Free-Space Coupling to Photonic Lanterns in the Presence of Tilt Errors

    Science.gov (United States)

    2017-05-01

    Analysis of Free- Space Coupling to Photonic Lanterns in the Presence of Tilt Errors Timothy M. Yarnall, David J. Geisler, Curt M. Schieler...Massachusetts Avenue Cambridge, MA 02139, USA Abstract—Free space coupling to photonic lanterns is more tolerant to tilt errors and F -number mismatch than...these errors. I. INTRODUCTION Photonic lanterns provide a means for transitioning from the free space regime to the single-mode fiber (SMF) regime by

  8. Solar Cycle Variability Induced by Tilt Angle Scatter in a Babcock-Leighton Solar Dynamo Model

    Science.gov (United States)

    Karak, Bidya Binay; Miesch, Mark

    2017-09-01

    We present results from a three-dimensional Babcock-Leighton (BL) dynamo model that is sustained by the emergence and dispersal of bipolar magnetic regions (BMRs). On average, each BMR has a systematic tilt given by Joy’s law. Randomness and nonlinearity in the BMR emergence of our model produce variable magnetic cycles. However, when we allow for a random scatter in the tilt angle to mimic the observed departures from Joy’s law, we find more variability in the magnetic cycles. We find that the observed standard deviation in Joy’s law of {σ }δ =15^\\circ produces a variability comparable to the observed solar cycle variability of ˜32%, as quantified by the sunspot number maxima between 1755 and 2008. We also find that tilt angle scatter can promote grand minima and grand maxima. The time spent in grand minima for {σ }δ =15^\\circ is somewhat less than that inferred for the Sun from cosmogenic isotopes (about 9% compared to 17%). However, when we double the tilt scatter to {σ }δ =30^\\circ , the simulation statistics are comparable to the Sun (˜18% of the time in grand minima and ˜10% in grand maxima). Though the BL mechanism is the only source of poloidal field, we find that our simulations always maintain magnetic cycles even at large fluctuations in the tilt angle. We also demonstrate that tilt quenching is a viable and efficient mechanism for dynamo saturation; a suppression of the tilt by only 1°-2° is sufficient to limit the dynamo growth. Thus, any potential observational signatures of tilt quenching in the Sun may be subtle.

  9. Effect of manual tilt adjustments on incident irradiance on fixed and tracking solar panels

    International Nuclear Information System (INIS)

    Lubitz, William David

    2011-01-01

    Hourly typical meteorological year (TMY3) data was utilized with the Perez radiation model to simulate solar radiation on fixed, azimuth tracking and two axis tracking surfaces at 217 geographically diverse temperate latitude sites across the contiguous United States of America. The optimum tilt angle for maximizing annual irradiation on a fixed south-facing panel varied from being equal to the latitude at low-latitude, high clearness sites, to up to 14 o less than the latitude at a north-western coastal site with very low clearness index. Across the United States, the optimum tilt angle for an azimuth tracking panel was found to be on average 19 o closer to vertical than the optimum tilt angle for a fixed, south-facing panel at the same site. Azimuth tracking increased annual solar irradiation incident on a surface by an average of 29% relative to a fixed south-facing surface at optimum tilt angle. Two axis tracking resulted in an average irradiation increase of 34% relative to the fixed surface. Introduction of manual surface tilt changes during the year produced a greater impact for non-tracking surfaces than it did for azimuth tracking surfaces. Even monthly tilt changes only resulted in an average annual irradiation increase of 5% for fixed panels and 1% for azimuth tracked surfaces, relative to using a single optimized tilt angle in each case. In practice, the decision whether to manually tilt panels requires balancing the added cost in labor and the panel support versus the extra energy generation and the cost value of that energy. A spreadsheet file is available that gives individual results for each of the 217 simulated sites.

  10. Long-wavelength tilting of the Australian continent since the Late Cretaceous

    OpenAIRE

    DiCaprio, Lydia; Gurnis, Michael; Müller, R. Dietmar

    2009-01-01

    Global sea level and the pattern of marine inundation on the Australian continent are inconsistent. We quantify this inconsistency and show that it is partly due to a long wavelength, anomalous, downward tilting of the continent to the northeast by 300 m since the Eocene. This downward tilting occurred as Australia approached the subduction systems in South East Asia and is recorded by the progressive inundation of the northern margin of Australia. From the Oligocene to the Pliocene, the long...

  11. Impaired tilt perception in Parkinson's disease: a central vestibular integration failure.

    Directory of Open Access Journals (Sweden)

    Giovanni Bertolini

    Full Text Available Impaired balance control is a hallmark symptom in Parkinson's disease (PD. Altered sensory-motor integration contributes to the deficiency. We aimed to determine whether impaired vestibular signal processing added to the disorder. We exposed patients (N = 11; 68±6y and age-matched healthy subjects (hS: N = 19; 65±11y on a motion platform in complete darkness to two consecutive forward tilt movements (12 series; N = 24; overall 288 trials and asked them to indicate which tilt was perceived larger. By combing tilt movements with translations we manipulated vestibular sensory input in order to investigate whether putative impairment resulted from a deficiency of the sensory organs (semicircular canals in 'single-SCC-cue-condition', otoliths in 'single-OT-cue-condition' themselves or to a sensory integration failure ('multi-cue-condition'.Tilt discrimination in the multi-cue-condition was inferior in patients compared to hS (p = 0.02. No significant differences between the two groups were found for both single-cue-conditions. Comparison of multi-cue-condition with a prediction resulting from the combination of both single-cue-conditions by optimal observer theory revealed that patients (p = 0.04, in contrast to hS, failed to efficiently combine SCC and OT information to improve tilt perception.We found that PD patients distinguished forward tilts less precise than hS, suggesting impaired vestibular perception. Tilt discrimination in patients, moreover, did not improve as much as in hS in conditions where both SCC and OT information was available compared to conditions where only SCC or OT cues were activated. The latter provides evidence that tilt misperception in PD most likely results from an integration failure of vestibular signals.

  12. Obtaining Volar Tilt in Distal Radius Fixation: Use of a Screw as a Proximal Post.

    Science.gov (United States)

    Watson, B Collier; Taylor, Benjamin C; Madsen, Adam; Persinger, Freddie D; Malarkey, Andy R

    2016-01-01

    Volar plating of distal radius fractures was introduced as a means to circumvent some of the issues with dorsal-based plating but has been shown not to be a complete panacea, as other advantages and challenges have subsequently been discovered. Careful attention and proper technique must be utilized to restore and maintain volar tilt. This study reports a technique of using a locking screw as a proximal peg to reliably obtain the volar tilt in a simple fashion.

  13. Estimation of pelvic tilt on anteroposterior X-rays - a comparison of six parameters

    International Nuclear Information System (INIS)

    Tannast, M.; Murphy, S.B.; Langlotz, F.; Anderson, S.E.; Siebenrock, K.A.

    2006-01-01

    To compare six different parameters described in literature for estimation of pelvic tilt on an anteroposterior pelvic radiograph and to create a simple nomogram for tilt correction of prosthetic cup version in total hip arthroplasty. Simultaneous anteroposterior and lateral pelvic radiographs are taken routinely in our institution and were analyzed prospectively. The different parameters (including three distances and three ratios) were measured and compared to the actual pelvic tilt on the lateral radiograph using simple linear regression analysis. One hundred and four consecutive patients (41 men, 63 women with a mean age of 31.7 years, SD 9.2 years, range 15.7-59.1 years) were studied. The strongest correlation between pelvic tilt and one of the six parameters for both men and women was the distance between the upper border of the symphysis and the sacrococcygeal joint. The correlation coefficient was 0.68 for men (P<0.001) and 0.61 for women (P<0.001). Based on this linear correlation, a nomogram was created that enables fast, tilt-corrected cup version measurements in clinical routine use. This simple method for correcting variations in pelvic tilt on plain radiographs can potentially improve the radiologist's ability to diagnose and interpret malformations of the acetabulum (particularly acetabular retroversion and excessive acetabular overcoverage) and post-operative orientation of the prosthetic acetabulum. (orig.)

  14. Nanoscale Tilt Measurement Using a Cyclic Interferometer with Phase Stepping and Multiple Reflections

    Science.gov (United States)

    Naderishahab, Tahereh

    High accuracy tilt or roll angle measurement is required for a variety of engineering and scientific applications. Optical interferometry is normally used because it is non-contact and can measure tilt with a very high degree of accuracy. In this thesis, a cyclic interferometer has been developed with four mirrors to measure tilt angles as small as a few nanoradians. To measure the phase, a novel and simple method of phase shift by polarization was developed to enhance measurement sensitivity and accuracy. Since the cyclic interferometer is insensitive to external vibrations and turbulences, polarization phase step was accomplished with relative ease. To introduce the phase shift, a quarter wave plate and a half wave plate were used with a polarized laser beam. Multiple reflections were also introduced in the cyclic interferometer to enhance tilt measurement capability. A new method was developed to evaluate phase and eventually measure the tilt even in the case of changing fringe visibility. The results of these studies show that the multiple reflection cyclic interferometer can be used to measure object tilts in the order of 0.2 nanoradians or 10. (-5) arc second.

  15. Uniform tilt-angle micromirror array for multi-object spectroscopy

    Science.gov (United States)

    Waldis, Severin; Clerc, Pierre-Andre; Zamkotsian, Frederic; Zickar, Michael; Noell, Wilfried; de Rooij, Nico

    2007-01-01

    We report on micromirror arrays being developed for the use as reflective slit mask in Multi Object Spectrographs for astronomical applications. The micromirrors are etched in bulk single crystal silicon whereas the cantilever type suspension is realized by surface micromachining. One micromirror element is 100μm x 200μm in size. The micromirrors are actuated electrostatically by electrodes located on a second chip. The use of silicon on insulator (SOI) wafers for both mirror and electrode chip ensures thermal compatibility for cryogenic operation. A system of multiple landing beams has been developed, which passively locks the mirror at a well defined tilt angle when actuated. The mechanical tilt angle obtained is 20 ° at a pull-in voltage of 90V. Measurements with an optical profiler showed that the tilt angle of the actuated and locked mirror is stable with a precision of one arc minute over a range of 15V. This locking system makes the tilt angle merely independent from process variations across the wafer and thus provides uniform tilt angle over the whole array. The precision on tilt angle from mirror to mirror measured is one arc minute. The surface quality of the mirrors in actuated state is better than 10nm peak-to-valley and the local roughness is around 1nm RMS.

  16. The Effects of Segmentation and Spatial Geometry on the Tilt Illusion

    Directory of Open Access Journals (Sweden)

    Cheng Qiu

    2012-10-01

    Full Text Available In the tilt illusion, when the orientation of the center and surround gratings differ by a small angle, the center grating appears to tilt away from the surround orientation (repulsion; however, for a large difference in angle, the center appears to tilt towards the surround orientation (attraction. Orientation perception therefore depends strongly on the context. Changes in two-dimensional configuration or three-dimensional scene geometry may alter the segmentation features between the center and surround, and cause variations in central orientation perception. We first measured the effect of two sources of segmentation information, contrast, and stereo disparity differences, on the strength of the tilt illusion in human observers. We observed: when the center contrast was high, both low-contrast surround and stereo depth segmentation cues reduced the amplitude of both the repulsion and attraction effect, relative to a high-contrast, 2D surround; a higher surround contrast (70% relative to the center (10% decreased the repulsion effect but increased both the range and magnitude of the attraction effect. Next, we examined the effect of perceptual grouping behind a 3D occluder ring between the center and surround on perceived central orientation. We observed significantly stronger tilt repulsion effects across occlusion than the condition with a ring at the same plane as the center and surround. We also found that the tilt repulsion is selective for the peripheral location of the surround. These results suggest that scene organization plays a role in central orientation perception.

  17. A novel method of measuring spatial rotation angle using MEMS tilt sensors

    International Nuclear Information System (INIS)

    Cao, Jian’an; Zhu, Xin; Zhang, Leping; Wu, Hao

    2017-01-01

    This paper presents a novel method of measuring spatial rotation angle with a dual-axis micro-electro-mechanical systems tilt sensor. When the sensor is randomly mounted on the surface of the rotating object, there are three unpredictable and unknown mounting position parameters: α , the sensor’s swing angle on the measuring plane; β , the angle between the rotation axis and the horizontal plane; and γ , the angle between the measuring plane and the rotation axis. Thus, the sensor’s spatial rotation model is established to describe the relationship between the measuring axis, rotation axis, and horizontal plane, and the corresponding analytical equations are derived. Furthermore, to eliminate the deviation caused by the uncertain direction of the rotation axis, an extra perpendicularly mounted, single-axis tilt sensor is combined with the dual-axis tilt sensor, forming a three-axis tilt sensor. Then, by measuring the sensors’ three tilts and solving the model’s equations, the object’s spatial rotation angle is obtained. Finally, experimental results show that the developed tilt sensor is capable of measuring spatial rotation angle in the range of  ±180° with an accuracy of 0.2° if the angle between the rotation axis and the horizontal plane is less than 75°. (paper)

  18. Position, Attitude, and Fault-Tolerant Control of Tilting-Rotor Quadcopter

    Science.gov (United States)

    Kumar, Rumit

    The aim of this thesis is to present algorithms for autonomous control of tilt-rotor quadcopter UAV. In particular, this research work describes position, attitude and fault tolerant control in tilt-rotor quadcopter. Quadcopters are one of the most popular and reliable unmanned aerial systems because of the design simplicity, hovering capabilities and minimal operational cost. Numerous applications for quadcopters have been explored all over the world but very little work has been done to explore design enhancements and address the fault-tolerant capabilities of the quadcopters. The tilting rotor quadcopter is a structural advancement of traditional quadcopter and it provides additional actuated controls as the propeller motors are actuated for tilt which can be utilized to improve efficiency of the aerial vehicle during flight. The tilting rotor quadcopter design is accomplished by using an additional servo motor for each rotor that enables the rotor to tilt about the axis of the quadcopter arm. Tilting rotor quadcopter is a more agile version of conventional quadcopter and it is a fully actuated system. The tilt-rotor quadcopter is capable of following complex trajectories with ease. The control strategy in this work is to use the propeller tilts for position and orientation control during autonomous flight of the quadcopter. In conventional quadcopters, two propellers rotate in clockwise direction and other two propellers rotate in counter clockwise direction to cancel out the effective yawing moment of the system. The variation in rotational speeds of these four propellers is utilized for maneuvering. On the other hand, this work incorporates use of varying propeller rotational speeds along with tilting of the propellers for maneuvering during flight. The rotational motion of propellers work in sync with propeller tilts to control the position and orientation of the UAV during the flight. A PD flight controller is developed to achieve various modes of the

  19. Perception of tilt (somatogravic illusion) in response to sustained linear acceleration during space flight

    Science.gov (United States)

    Clement, G.; Moore, S. T.; Raphan, T.; Cohen, B.

    2001-01-01

    During the 1998 Neurolab mission (STS-90), four astronauts were exposed to interaural and head vertical (dorsoventral) linear accelerations of 0.5 g and 1 g during constant velocity rotation on a centrifuge, both on Earth and during orbital space flight. Subjects were oriented either left-ear-out or right-ear-out (Gy centrifugation), or lay supine along the centrifuge arm with their head off-axis (Gz centrifugation). Pre-flight centrifugation, producing linear accelerations of 0.5 g and 1 g along the Gy (interaural) axis, induced illusions of roll-tilt of 20 degrees and 34 degrees for gravito-inertial acceleration (GIA) vector tilts of 27 degrees and 45 degrees , respectively. Pre-flight 0.5 g and 1 g Gz (head dorsoventral) centrifugation generated perceptions of backward pitch of 5 degrees and 15 degrees , respectively. In the absence of gravity during space flight, the same centrifugation generated a GIA that was equivalent to the centripetal acceleration and aligned with the Gy or Gz axes. Perception of tilt was underestimated relative to this new GIA orientation during early in-flight Gy centrifugation, but was close to the GIA after 16 days in orbit, when subjects reported that they felt as if they were 'lying on side'. During the course of the mission, inflight roll-tilt perception during Gy centrifugation increased from 45 degrees to 83 degrees at 1 g and from 42 degrees to 48 degrees at 0.5 g. Subjects felt 'upside-down' during in-flight Gz centrifugation from the first in-flight test session, which reflected the new GIA orientation along the head dorsoventral axis. The different levels of in-flight tilt perception during 0.5 g and 1 g Gy centrifugation suggests that other non-vestibular inputs, including an internal estimate of the body vertical and somatic sensation, were utilized in generating tilt perception. Interpretation of data by a weighted sum of body vertical and somatic vectors, with an estimate of the GIA from the otoliths, suggests that

  20. Octahedral tilt transitions in the relaxor ferroelectric Na1/2Bi1/2TiO3

    International Nuclear Information System (INIS)

    Meyer, Kai-Christian; Gröting, Melanie; Albe, Karsten

    2015-01-01

    The kinetics of octahedral tilt transitions in the lead-free relaxor material sodium bismuth titanate Na 1/2 Bi 1/2 TiO 3 (NBT) is investigated by electronic structure calculations within density functional theory. Energy barriers for transitions between tetragonal, rhombohedral and orthorhombic tilts in cation configurations with [001]- and [111]-order on the A-sites are determined by nudged elastic band calculations. By tilting entire layers of octahedra simultaneously we find that the activation energy is lower for structures with 001-order compared to such with 111-order. The energetic coupling between differently tilted layers is, however, negligibly small. By introducing a single octahedral defect we create local tilt disorder and find that the deformation energy of the neighboring octahedra is less in a rhombohedral than in a tetragonal structure. By successively increasing the size of clusters of orthorhombic defects in a rhombohedral matrix with 001-order, we determine a critical cluster size of about 40 Å . Thus groups of about ten octahedra can be considered as nuclei for polar nanoregions, which are the cause of the experimentally observed relaxor behavior of NBT. - Graphical abstract: Nine orthorhombic oxygen octahedral tilt defects in a rhombohedral tilt configuration. - Highlights: • Chemical order influences energy barriers of octahedral tilt transitions. • The octahedral deformation energy is lower in rhombohedral phases. • Tilt defect clusters are more likely in rhombohedral structures. • Tilt defect clusters can act as nuclei for polar nanoregions

  1. Technologie výroby horizontálního kabelového žlabu pro nízkonapěťové rozváděče ABB

    OpenAIRE

    Attasek, Ondřej

    2016-01-01

    V bakalářské práci je hlavním úkolem výroba součásti, která je z pozinkovaného ocelového plechu z materiálu DX51D+AZ/+Z o tloušťce 1,5 mm. Součást se vyrábí pomocí technologie stříhání a několika násobným ohýbáním. Hlavním záměrem je navrhnout technologický postup výroby kabelového žlabu na montáž nízkonapěťového rozváděče pro firmu ABB, s.r.o. Roční produkce se předpokládá na 2 650 ks. Součástí práce jsou dále potřebné technologické výpočty pro nástřihový plán, střižné síly a síly pro ohýbán...

  2. Technologie výroby vertikálního kabelového žlabu pro nízkonapěťové rozvaděče ABB

    OpenAIRE

    Šín, Martin

    2017-01-01

    Bakalářská práce představuje návrh technologie výroby vertikálního kabelového žlabu pro nízkonapěťové rozváděče firmy ABB. Sestava je složena ze dvou částí. Kabelový žlab a stínící přepážka jsou vyrobeny z pozinkovaného plechu 11 321, jakosti DX52D+Z275 MB o tloušťce materiálu 1 mm. Na základě studie a výpočtů byla navržena výroba součásti pomocí děrování, řezání laserem, ohýbání na ohraňovacím lisu a spojení jednotlivých částí pomocí metody clinching. Vše doloženo výpočtem a výkresovou dokum...

  3. The sagittal pelvic tilt index as a criterion in the evaluation of spondylolisthesis. Preliminary observations.

    Science.gov (United States)

    Schwab, F J; Farcy, J P; Roye, D P

    1997-07-15

    Radiographic analysis of a pediatric population with spondylolisthesis was performed to examine sagittal plane pelvic rotation and degree of slip over time. To determine whether the degree of standing sagittal offset of L5 with respect to the acetabulum correlated with slip progression and symptoms. The natural history of isthmic spondylolisthesis remains unclear. Attempts to predict slip progression in the clinical setting, and thus the possible need for eventual surgical intervention, remain imprecise. Predicting slip progression based on sagittal alignment of the L5 vertebra with respect to the acetabulum has been proposed by some investigators. Fifty-two children and adolescents were followed clinically and radiographically for an average of 5.6 years. Serial lateral standing radiographs that included the hips and lumbar spine were measured to compute a sagittal pelvic tilt index. The latter value is a ratio of relative distances from the center of S2 to the projection of L5 and the center of the femoral heads on the horizontal. Of the 52 patients studied, 38 have remained asymptomatic without significant slip progression or change in sagittal pelvic tilt index ratio. Of the original group, 13 patients had significant symptoms and revealed a decrease in the sagittal pelvic tilt index over time. Eight of the 13 stabilized at the end of adolescence, whereas 5 had continued decrease in the sagittal pelvic tilt index ratio. These five required operative treatment for pain and progressive slip. The sagittal pelvic tilt index gives the examiner an objective measure of the stability of the lumbosacral junction by quantifying the relationship between S2, the center of the hip, and L5. A decreasing sagittal pelvic tilt index ratio in this preliminary series correlated with slip progression and risk of conservative treatment failure, whereas those patients with a stable sagittal pelvic tilt index did not progress and remained clinically asymptomatic.

  4. The structure of strongly tilted current sheets in the Earth magnetotail

    Directory of Open Access Journals (Sweden)

    I. Y. Vasko

    2014-02-01

    Full Text Available We investigate strongly tilted (in the y–z GSM plane current sheets (CSs in the Earth magnetotail using data from the Cluster mission. We analyze 29 CS crossings observed in 2001–2004. The characteristic current density, magnetic field at the CS boundary and the CS thickness of strongly tilted CSs are similar to those reported previously for horizontal (not tilted CSs. We confirm that strongly tilted CSs are generally characterized by a rather large northward component of the magnetic field. The field-aligned current in strongly tilted CSs is on average two times larger than the transverse current. The proton adiabaticity parameter, κp, is larger than 0.5 in 85% of strongly tilted CSs due to the large northward magnetic field. Thus, the proton dynamics is stochastic for 18 current sheets with 0.5 p p > 3, whereas electrons are magnetized for all observed current sheets. Strongly tilted CSs provide a unique opportunity to measure the electric field component perpendicular to the CS plane. We find that most of the electric field perpendicular to the CS plane is due to the decoupling of electron and ion motions (plasma polarization. For 27 CSs we determine profiles of the electrostatic potential, which is due to the plasma polarization. Drops in the potential between the neutral plane and the CS boundary are within the range of 200 V to 12 kV, while maximal values of the electric field are within the range of 0.2 mV m−1 to 8 mV m−1. For 16 CSs the observed potentials are in accordance with Ohm's law, if the electron current density is assumed to be comparable to the total current density. In 15 of these CSs the profile of the polarization potential is approximately symmetric with respect to the neutral plane and has minimum therein.

  5. Estimating 3D tilt from local image cues in natural scenes

    Science.gov (United States)

    Burge, Johannes; McCann, Brian C.; Geisler, Wilson S.

    2016-01-01

    Estimating three-dimensional (3D) surface orientation (slant and tilt) is an important first step toward estimating 3D shape. Here, we examine how three local image cues from the same location (disparity gradient, luminance gradient, and dominant texture orientation) should be combined to estimate 3D tilt in natural scenes. We collected a database of natural stereoscopic images with precisely co-registered range images that provide the ground-truth distance at each pixel location. We then analyzed the relationship between ground-truth tilt and image cue values. Our analysis is free of assumptions about the joint probability distributions and yields the Bayes optimal estimates of tilt, given the cue values. Rich results emerge: (a) typical tilt estimates are only moderately accurate and strongly influenced by the cardinal bias in the prior probability distribution; (b) when cue values are similar, or when slant is greater than 40°, estimates are substantially more accurate; (c) when luminance and texture cues agree, they often veto the disparity cue, and when they disagree, they have little effect; and (d) simplifying assumptions common in the cue combination literature is often justified for estimating tilt in natural scenes. The fact that tilt estimates are typically not very accurate is consistent with subjective impressions from viewing small patches of natural scene. The fact that estimates are substantially more accurate for a subset of image locations is also consistent with subjective impressions and with the hypothesis that perceived surface orientation, at more global scales, is achieved by interpolation or extrapolation from estimates at key locations. PMID:27738702

  6. Human muscle sympathetic neural and haemodynamic responses to tilt following spaceflight

    Science.gov (United States)

    Levine, Benjamin D.; Pawelczyk, James A.; Ertl, Andrew C.; Cox, James F.; Zuckerman, Julie H.; Diedrich, Andre; Biaggioni, Italo; Ray, Chester A.; Smith, Michael L.; Iwase, Satoshi; hide

    2002-01-01

    Orthostatic intolerance is common when astronauts return to Earth: after brief spaceflight, up to two-thirds are unable to remain standing for 10 min. Previous research suggests that susceptible individuals are unable to increase their systemic vascular resistance and plasma noradrenaline concentrations above pre-flight upright levels. In this study, we tested the hypothesis that adaptation to the microgravity of space impairs sympathetic neural responses to upright posture on Earth. We studied six astronauts approximately 72 and 23 days before and on landing day after the 16 day Neurolab space shuttle mission. We measured heart rate, arterial pressure and cardiac output, and calculated stroke volume and total peripheral resistance, during supine rest and 10 min of 60 deg upright tilt. Muscle sympathetic nerve activity was recorded in five subjects, as a direct measure of sympathetic nervous system responses. As in previous studies, mean (+/- S.E.M.) stroke volume was lower (46 +/- 5 vs. 76 +/- 3 ml, P = 0.017) and heart rate was higher (93 +/- 1 vs. 74 +/- 4 beats min(-1), P = 0.002) during tilt after spaceflight than before spaceflight. Total peripheral resistance during tilt post flight was higher in some, but not all astronauts (1674 +/- 256 vs. 1372 +/- 62 dynes s cm(-5), P = 0.32). No crew member exhibited orthostatic hypotension or presyncopal symptoms during the 10 min of postflight tilting. Muscle sympathetic nerve activity was higher post flight in all subjects, in supine (27 +/- 4 vs. 17 +/- 2 bursts min(-1), P = 0.04) and tilted (46 +/- 4 vs. 38 +/- 3 bursts min(-1), P = 0.01) positions. A strong (r(2) = 0.91-1.00) linear correlation between left ventricular stroke volume and muscle sympathetic nerve activity suggested that sympathetic responses were appropriate for the haemodynamic challenge of upright tilt and were unaffected by spaceflight. We conclude that after 16 days of spaceflight, muscle sympathetic nerve responses to upright tilt are normal.

  7. TILT ANGLE AND FOOTPOINT SEPARATION OF SMALL AND LARGE BIPOLAR SUNSPOT REGIONS OBSERVED WITH HMI

    Energy Technology Data Exchange (ETDEWEB)

    McClintock, B. H. [University of Southern Queensland, Toowoomba, 4350 (Australia); Norton, A. A., E-mail: u1049686@umail.usq.edu.au, E-mail: aanorton@stanford.edu [HEPL, Stanford University, Palo Alto, CA 94305 (United States)

    2016-02-10

    We investigate bipolar sunspot regions and how tilt angle and footpoint separation vary during emergence and decay. The Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory collects data at a higher cadence than historical records and allows for a detailed analysis of regions over their lifetimes. We sample the umbral tilt angle, footpoint separation, and umbral area of 235 bipolar sunspot regions in Helioseismic and Magnetic Imager—Debrecen Data with an hourly cadence. We use the time when the umbral area peaks as time zero to distinguish between the emergence and decay periods of each region and we limit our analysis of tilt and separation behavior over time to within ±96 hr of time zero. Tilt angle evolution is distinctly different for regions with small (≈30 MSH), midsize (≈50 MSH), and large (≈110 MSH) maximum umbral areas, with 45 and 90 MSH being useful divisions for separating the groups. At the peak umbral area, we determine median tilt angles for small (7.°6), midsize (5.°9), and large (9.°3) regions. Within ±48 hr of the time of peak umbral area, large regions steadily increase in tilt angle, midsize regions are nearly constant, and small regions show evidence of negative tilt during emergence. A period of growth in footpoint separation occurs over a 72-hr period for all of the regions from roughly 40 to 70 Mm. The smallest bipoles (<9 MSH) are outliers in that they do not obey Joy's law and have a much smaller footpoint separation. We confirm the Muñoz-Jaramillo et al. results that the sunspots appear to be two distinct populations.

  8. Mechanisms of Günther Tulip filter tilting during transfemoral placement.

    Science.gov (United States)

    Matsui, Y; Horikawa, M; Ohta, K; Jahangiri Noudeh, Y; Kaufman, J A; Farsad, K

    The purpose of this study was to characterize the mechanisms of Günther Tulip filter (GTF) tilting during transfemoral placement in an experimental model with further validation in a clinical series. In an experimental study, 120 GTF placements in an inferior vena cava (IVC) model were performed using 6 configurations of pre-deployment filter position. The angle between the pre-deployment filter axis and IVC axis, and the proximity of the constrained filter legs to IVC wall prior to deployment were evaluated. The association of those pre-deployment factors with post-deployment filter tilting was analyzed. The association noted in the experimental study was then evaluated in a retrospective clinical series of 21 patients. In the experimental study, there was a significant association between the pre-deployment angle and post-deployment filter tilting (P<0.0001). With a low pre-deployment angle (≤5°), a significant association was noted between filter tilting and the proximity of the constrained filter legs to the far IVC wall (P=0.001). In a retrospective clinical study, a significant association between the pre-deployment angle and post-deployment filter tilting was also noted with a linear regression model (P=0.026). Significant association of the pre-deployment angle with post-deployment GTF tilting was shown in both the experimental and clinical studies. The experimental study also showed that proximity of filter legs is relevant when pre-deployment angle is small. Addressing these factors may result in a lower incidence of filter tilting. Copyright © 2017 Editions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

  9. POST TENEBRES LUX : ABBE. El videoarte interdisciplinar y Monte Verità. Un método de análisis para la creación y caracterización de personajes, mediante la psicología transpersonal y el eneagrama.

    OpenAIRE

    HEREDIA PEREA, BEATRIZ

    2017-01-01

    This Doctoral Thesis POST TENEBRES LUX: ABBE, investigates the interdisciplinary video art in the international artistic context, echoing the creative origins of the multidisciplinary concept in Monte Verità, (Switzerland). Where in the inter-war period it served as a refuge and model for the creation of a new paradigm of society, which would later crystallize in the hippie movement in the USA, and that would spread throughout the world. From this we deepen in the different artistic disciplin...

  10. Perceived direction of gravity and the body-axis during static whole body roll-tilt in healthy subjects.

    Science.gov (United States)

    Tamura, Atsushi; Wada, Yoshiro; Inui, Takuo; Shiotani, Akihiro

    2017-10-01

    We used the subjective visual vertical (SVV) and two different subjective visual body axis (SVBA) methods to quantify roll-tilt perception under gravity, and investigated the characteristics of these methods during static roll-tilt. In addition, we independently developed a compact device to facilitate evaluation of SVBA in different gravitational environments. Ten male volunteers participated in this study. We created a roll-tilt environment using a flight simulator in a dark room. The cockpit of the simulator was tilted leftward or rightward (-30°, -20°, -10°, 0°, 10°, 20° and 30°) in each randomly ordered trial. We quantified roll-tilt perception such that the experiment was conducted under 21 different conditions per participant. We found no significant differences among the SVV error and the two types of SVBA error. The SVV and the SVBA methods may be useful for evaluating subjective roll-tilt perception.

  11. Tilt signals associated with a small eruption at Asama Volcano, Japan

    Science.gov (United States)

    Ohminato, T.

    2013-12-01

    It is well known that the acceleration input to a seismometer consists of translational acceleration and tilt-related acceleration. The lower the frequency is, the more contribution is from the tilt-related acceleration. The tilt contribution can be easily extracted from the velocity output of broadband seismometers by the following simple procedure. The roll-off of the transfer function of the broadband seismometer in the frequency range below its characteristic frequency is proportional to the square of frequency. It means that the sensor output in this frequency range is proportional to the time-derivative of the ground acceleration. The result of time integration of the signal in this frequency range is, thus proportional to the ground acceleration, which are proportional to the ground tilt. As long as we concentrate on the low enough frequency range, this simple integration procedure is equivalent to the traditional procedure of sensor-response removal followed by transfer to the tilt response On February 2, 2009, a small eruption occurred at Mt. Asama, central Japan. A broadband seismic network operated by Earthquake Research Institute, University of Tokyo, detected tilt-related signals during the eruption. According to the tilt signals that were extracted by the above mentioned procedure, an inflation started 30 minutes before the summit eruption. The inflation was followed by a rapid deflation due to the summit eruption. At the stations relatively far from the summit, while the tilt changes before the eruption were below noise level and thus were not detected, the tilt changes after the eruption were clearly detected by most of the stations around Mt. Asama. The post eruption tilt signals were oriented not to the summit but to the northwestern side of Mt. Asama. The tilt signals before and during the eruption observed at the near-summit stations are interpreted as an accumulation and release of pressure beneath the summit crater before and after the

  12. Optimal tilt-angles of all-glass evacuated tube solar collectors

    International Nuclear Information System (INIS)

    Tang, Runsheng; Gao, Wenfeng; Yu, Yamei; Chen, Hua

    2009-01-01

    In this paper, a detailed mathematical procedure is developed to estimate daily collectible radiation on single tube of all-glass evacuated tube solar collectors based on solar geometry, knowledge of two-dimensional radiation transfer. Results shows that the annual collectible radiation on a tube is affected by many factors such as collector type, central distance between tubes, size of solar tubes, tilt and azimuth angles, use of diffuse flat reflector (DFR, in short); For collectors with identical parameters, T-type collectors (collectors with solar tubes tilt-arranged) annually collect slightly more radiation than H-type collectors (those with solar tubes horizontally arranged) do. The use of DFR can significantly improve the energy collection of collectors. Unlike the flat-plate collectors, all-glass evacuated tube solar collectors should be generally mounted with a tilt-angle less than the site latitude in order to maximize the annual energy collection. For most areas with the site latitude larger than 30 o in China, T-type collectors should be installed with a tilt-angle about 10 o less than the site latitude, whereas for H-type collectors without DFR, the reasonable tilt-angle should be about 20 o less than the site latitude. Effects of some parameters on the annual collectible radiation on the collectors are also presented.

  13. Design of a Piezoelectric-Driven Tilt Mirror for a Fast Laser Scanner

    Science.gov (United States)

    Park, Jung-Ho; Lee, Hu-Seung; Lee, Jae-Hoon; Yun, So-Nam; Ham, Young-Bog; Yun, Dong-Won

    2012-09-01

    Recently, laser scanners have been used for laser processing such as cutting, welding, and grooving, especially in the automotive industry. The laser scanners need a high-speed driving to minimize cracks caused by thermal shock of brittle materials. Therefore, a novel laser processing system that is composed of a laser source and a piezoelectric-driven tilt mirror to control the reflection angle of the laser beam, and a stage equipped with the tilt mirror has been investigated. In this study, a piezoelectric-driven tilt mirror is designed and analyzed for scanning performance to achieve a beam spot of 30 µm, a pattern width of 1 mm, an overlap ratio of 70% of the circle area, and a scanning speed of 1 m/s. Then, structural analysis of the tilt mirror with three piezoelectric actuators is performed to determine the maximum reflection angle and resonance frequency. Finally, a prototype tilt mirror is fabricated and its basic characteristics are experimentally investigated and discussed.

  14. Micromirror with large-tilting angle using Fe-based metallic glass.

    Science.gov (United States)

    Lee, Jae-Wung; Lin, Yu-Ching; Kaushik, Neelam; Sharma, Parmanand; Makino, Akihiro; Inoue, Akihisa; Esashi, Masayoshi; Gessner, Thomas

    2011-09-01

    For enhancing the micromirror properties like tilting angle and stability during actuation, Fe-based metallic glass (MG) was applied for torsion bar material. A micromirror with mirror-plate diameter of 900 μm and torsion bar dimensions length 250 μm, width 30 μm and thickness 2.5 μm was chosen for the tilting angle tests, which were performed by permanent magnets and electromagnet setup. An extremely large tilting angle of over -270° was obtained from an activation test by permanent magnet that has approximately 0.2 T of magnetic strength. A large mechanical tilting angle of over -70° was obtained by applying approximately 1.1 mT to the mirror when 93 mAwas applied to solenoid setup. The large-tilting angle of the micromirror is due to the torsion bar, which was fabricated with Fe-based MG thin film that has large elastic strain limit, fracture toughness, and excellent magnetic property.

  15. Topological Edge States at a Tilt Boundary in Gated Multilayer Graphene

    Directory of Open Access Journals (Sweden)

    Abolhassan Vaezi

    2013-06-01

    Full Text Available Despite much interest in engineering new topological surface (edge states using structural defects, such topological surface states have not been observed yet. We show that recently imaged tilt boundaries in gated multilayer graphene should support topologically protected gapless edge states. We approach the problem from two perspectives: the microscopic perspective of a tight-binding model and an ab initio calculation on a bilayer, and the symmetry-protected topological (SPT state perspective for a general multilayer. Hence, we establish the tilt-boundary edge states as the first concrete example of the edge states of symmetry-protected Z-type SPT, protected by no-valley mixing, electron-number conservation, and time-reversal T symmetries. Further, we discuss possible phase transitions between distinct SPTs upon symmetry changes. Combined with a recently imaged tilt-boundary network, our findings may explain the long-standing puzzle of subgap conductance in gated bilayer graphene. This proposal can be tested through future transport experiments on tilt boundaries. In particular, the tilt boundaries offer an opportunity for the in situ imaging of topological edge transport.

  16. System for the Automatic Estimation of the Tilt Angle of a Flat Solar Collector

    Directory of Open Access Journals (Sweden)

    Jorge Fonseca-Campos

    2017-08-01

    Full Text Available In this work, a compact system for the automatic estimation of the tilt angle at any location of the world is presented. The system components are one computer, one GPS receiver and one Python program. The tilt angle is calculated through the maximization of the flux of direct radiation incident upon a flat solar collector. An estimation of the adjustments of this angle at different time periods are obtained. This angle is calculated in steps of six minutes during a whole year. Daily, monthly, biannually and yearly averages of this value are obtained. A comparison of the energetic gain when the tilt angle changes at the different time periods is made as well. Because, the algorithm doesn’t receive as an input the solar radiation incident upon a surface at the location of the calculation, a comparison was made between the results obtained and the results reported for the monthly tilt angle of 22 different places. The root mean square error obtained with this comparison was between 1.5 and 9.5 degrees. The monthly tilt angle estimated deviated in average for less than 6.3° with respect to the values reported for the different locations. Finally, the application of a correction factor in the monthly estimated angles is proposed, which might increase the collected energy.

  17. Establishment of Approximate Analytical Model of Oil Film Force for Finite Length Tilting Pad Journal Bearings

    Directory of Open Access Journals (Sweden)

    Yongliang Wang

    2015-01-01

    Full Text Available Tilting pad bearings offer unique dynamic stability enabling successful deployment of high-speed rotating machinery. The model of dynamic stiffness, damping, and added mass coefficients is often used for rotordynamic analyses, and this method does not suffice to describe the dynamic behaviour due to the nonlinear effects of oil film force under larger shaft vibration or vertical rotor conditions. The objective of this paper is to present a nonlinear oil force model for finite length tilting pad journal bearings. An approximate analytic oil film force model was established by analysing the dynamic characteristic of oil film of a single pad journal bearing using variable separation method under the dynamic π oil film boundary condition. And an oil film force model of a four-tilting-pad journal bearing was established by using the pad assembly technique and considering pad tilting angle. The validity of the model established was proved by analyzing the distribution of oil film pressure and the locus of journal centre for tilting pad journal bearings and by comparing the model established in this paper with the model established using finite difference method.

  18. Annual Optimum Tilt Angle Prediction of Solar Collector using PSO Estimator

    Science.gov (United States)

    Dixit, T. V.; Yadav, Anamika; pre="Senior Member ">IEEE,

    2017-08-01

    The amount of solar flux falls on solar collector depends on tilt angle and orientation of collector from the surface. By efficiently regulating the tilt and orientation of solar collector unnecessary loss in potential power can be minimized. In general, for north hemisphere, south facing of the collector is considered as optimum orientation. There are several metrological and geographical factors which affect the optimum tilt angle. In this paper, the PSO estimator has been proposed in order to find optimum tilt angle on annual basis. The results of PSO estimators are compared with ANN estimator and satellite (RETScreen software) data. To evaluate the performance of proposed model MBE, RMSE, Error range, percentage annual error as well as direct method of statistical study have been carried out. During annual tilt angle prediction the annual percentage errors of proposed method and RETScreensoftware data are 0.03% and 7.03% respectively with respect to ANN results. Finally, the average percentage error indicates that the proposed estimator gives better prediction as compared to satellite based results for collecting maximum solar flux at surface of solar collector.

  19. Comparison of decentration and tilt between one piece and three piece polymethyl methacrylate intraocular lenses

    Science.gov (United States)

    Hayashi, K.; Hayashi, H.; Nakao, F.; Hayashi, F.

    1998-01-01

    BACKGROUND—The extent of the decentration and tilt was prospectively compared between one piece polymethyl methacrylate (PMMA) and three piece PMMA intraocular lenses (IOLs) which were implanted in the capsular bag after performing continuous curvilinear capsulorhexis.
METHODS—91 patients underwent a one piece PMMA IOL implantation in one eye as well as the implantation of the three piece PMMA IOL with polyvinylidene fluoride loops in the opposite eye. The length of the lens decentration and the angle of the tilt were quantitated using the anterior eye segment analysis system (EAS-1000) at 1 week as well as 1, 3, and 6 months postoperatively.
RESULTS—The mean length of the decentration in the one piece IOL was smaller than that in the three piece IOL at 1 week (p=0.0092), 1 month (p=0.0044), 3 months (p=0.0069), and 6 months (p=0.0010) postoperatively. However, no significant difference was found in the degree of the tilt between the two types of IOLs throughout the observation periods.
CONCLUSION—These results clarified that the one piece PMMA IOL with rigid PMMA haptics implanted in the capsular bag provides a better centration than the three piece PMMA IOL with flexible haptics, whereas the tilt was the same between the two types of IOLs.

 Keywords: intraocular lens; decentration; tilt; continuous curvilinear capsulorhexis PMID:9640193

  20. Rat Cardiovascular Responses to Whole Body Suspension: Head-down and Non-Head-Down Tilt

    Science.gov (United States)

    Musacchia, X. J.; Steffen, Joseph M.; Dombrowski, Judy

    1992-01-01

    The rat whole body suspension technique mimics responses seen during exposure to microgravity and was evaluated as a model for cardiovascular responses with two series of experiments. In one series, changes were monitored in chronically catheterized rats during 7 days of Head-Down Tilt (HDT) or Non-Head-Down Tilt (N-HDT) and after several hours of recovery. Elevations of mean arterial (MAP), systolic, and diastolic pressures of approx. 20 % (P less than 0.05) in HDT rats began as early as day 1 and were maintained for the duration of suspension. Pulse pressures were relatively unaffected, but heart rates were elevated approx. 10 %. During postsuspension (2-7 h), most cardiovascular parameters returned to presuspension levels. N-HDT rats exhibited elevations chiefly on days 3 and 7. In the second series, blood pressure was monitored in 1- and 3-day HDT and N-HDT rats to evaluate responses to rapid head-up tilt. MAP, systolic and diastolic pressures, and HR were elevated (P less than 0.05) in HDT and N-HDT rats during head-up tilt after 1 day of suspension, while pulse pressures remained un changed. HDT rats exhibited elevated pretilt MAP and failed to respond to rapid head-up tilt with further increase of MAP on day 3, indicating some degree of deconditioning. The whole body suspended rat may be useful as a model to better understand responses of rats exposed to microgravity.

  1. Maintaining Low Voiding Solder Die Attach for Power Die While Minimizing Die Tilt

    Energy Technology Data Exchange (ETDEWEB)

    Hamm, Randy; Peterson, Kenneth A.

    2015-10-01

    This paper addresses work to minimize voiding and die tilt in solder attachment of a large power die, measuring 9.0 mm X 6.5 mm X 0.1 mm (0.354” x 0.256” x 0.004”), to a heat spreader. As demands for larger high power die continue, minimizing voiding and die tilt is of interest for improved die functionality, yield, manufacturability, and reliability. High-power die generate considerable heat, which is important to dissipate effectively through control of voiding under high thermal load areas of the die while maintaining a consistent bondline (minimizing die tilt). Voiding was measured using acoustic imaging and die tilt was measured using two different optical measurement systems. 80Au-20Sn solder reflow was achieved using a batch vacuum solder system with optimized fixturing. Minimizing die tilt proved to be the more difficult of the two product requirements to meet. Process development variables included tooling, weight and solder preform thickness.

  2. Immediate Loading of Tilted and Axial Posterior Implants in the Edentulous Maxillary Arch: A Retrospective Comparison of 5-Year Outcomes.

    Science.gov (United States)

    Toljanic, Joseph A; Ekstrand, Karl; Baer, Russell A; Thor, Andreas

    The purpose of this study was to retrospectively compare long-term outcomes for immediately loaded tilted and axial implants placed in the posterior region of the edentulous maxillary arch. Data obtained from a 5-year prospective study designed to assess clinical outcomes following immediate loading of implants with screw-retained fixed restorations in the edentulous maxillary arch were retrospectively reviewed. Where insufficient alveolar bone was available for axial placement of the posterior-most implant on each side of the arch, tilted placement was employed. Implant survival and marginal bone level changes for these tilted and axial posterior implants were compared. Fifty-one subjects received 64 tilted and 38 axial posterior implants. Forty subjects with 53 tilted and 34 axial posterior implants returned for follow-up after 5 years. Five tilted and seven axial implants failed, representing an 89% and 86% survival proportion, respectively. The mean marginal bone loss was 0.79 (SD: 1.42) mm for tilted implants and 0.14 (SD: 0.34) mm for axial implants. The differences in survival proportions and marginal bone loss between axial and tilted implants were not statistically significant. Predictable long-term implant rehabilitation may be achieved in the edentulous maxillary arch using posterior tilted implants in combination with immediate loading.

  3. Numerical study of crucial parameters in tilt casting for titanium aluminides

    Directory of Open Access Journals (Sweden)

    Hong Wang

    2011-08-01

    Full Text Available Numerical modeling of the tilt casting process for TiAl alloys was investigated to achieve a tranquil mould filling and TiAl castings free of defects. Titanium alloys are very reactive in molten state, so they are widely melted in cold crucible, e.g. the Induction Skull Melting (ISM furnace. Then the crucible holding the molten metal together with the mould is rotated to transfer the metal into the mould — ISM+ tilt casting. This paper emphasizes the effect of crucial parameters on mould filling and solidification of the castings during tilt casting. All crucial parameters, such as rotation rate, rotation profile, venting, initial mould temperature, casting orientation, feeder design, change of radius in 'T' junction and mould insulation have been discussed using numerical modeling data. Simulations were performed using a 3D CFD code PHYSICA implemented with front tracking, heat transfer algorithms and a turbulence model (which accounts for an advancing solid front.

  4. Effect of long-range structural corrugations on magnetotransport properties of phosphorene in tilted magnetic field

    Science.gov (United States)

    Mogulkoc, A.; Modarresi, M.; Rudenko, A. N.

    2017-08-01

    Rippling is an inherent quality of two-dimensional materials playing an important role in determining their properties. Here, we study the effect of structural corrugations on the electronic and transport properties of monolayer black phosphorus (phosphorene) in the presence of tilted magnetic field. We follow a perturbative approach to obtain analytical corrections to the spectrum of Landau levels induced by a long-wavelength corrugation potential. We show that surface corrugations have a non-negligible effect on the electronic spectrum of phosphorene in tilted magnetic field. Particularly, the Landau levels are shown to exhibit deviations from the linear field dependence. The observed effect become especially pronounced at large tilt angles and corrugation amplitudes. Magnetotransport properties are further examined in the low temperature regime taking into account impurity scattering. We calculate magnetic field dependence of the longitudinal and Hall resistivities and find that the nonlinear effects reflecting the corrugation might be observed even in moderate fields (B <10 T).

  5. Keblish's lateral surgical approach enhances patellar tilt in valgus knee arthroplasty

    Directory of Open Access Journals (Sweden)

    José Roberto Tonelli Filho

    Full Text Available ABSTRACT OBJECTIVE: To compare the clinical and radiological outcomes of conventional medial and lateral approaches for total knee replacement in the valgus osteoarthritic knee. METHODS: In this randomized controlled trial, 21 patients with valgus knee osteoarthritis were randomized to total knee replacement through medial or lateral approach. The primary outcome was radiographic patellar tilt. Secondary outcomes were visual analog scale of pain, postoperative levels of hemoglobin, and clinical aspect of the operative wound. RESULTS: There were no differences between the groups regarding other clinical variables. Mean lateral tilt of the patella was 3.1 degrees (SD ± 5.3 in the lateral approach group and 18 degrees (SD ± 10.2 in the medial approach group (p = 0.02. There were no differences regarding the secondary outcomes. CONCLUSION: Lateral approach provided better patellar tilt following total knee replacement in valgus osteoarthritic knee.

  6. Design and initial characterization of a compact, ultra high vacuum compatible, low frequency, tilt accelerometer

    Energy Technology Data Exchange (ETDEWEB)

    O’Toole, A., E-mail: amandajotoole@gmail.com, E-mail: riccardo.desalvo@gmail.com [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, 405 Hilgard Ave, Los Angeles, California 90095 (United States); Peña Arellano, F. E. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Rodionov, A. V.; Kim, C. [California Institute of Technology, Pasadena, California 91125 (United States); Shaner, M.; Asadoor, M. [Mayfield Senior School, 500 Bellefontaine Street Pasadena, California 91105 (United States); Sobacchi, E. [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa (Italy); Dergachev, V.; DeSalvo, R., E-mail: amandajotoole@gmail.com, E-mail: riccardo.desalvo@gmail.com [LIGO Laboratory, California Institute of Technology, MS 100-36, Pasadena, California 91125 (United States); Bhawal, A. [Arcadia High School, 180 Campus Drive, Arcadia, California 91007 (United States); Gong, P. [Department of Precision Instrument, Tsinghua University, Beijing 100084 (China); Lottarini, A. [Department of Computer Science, University of Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Minenkov, Y. [Sezione INFN Tor Vergata, via della Ricerca Scientfica 1, 00133 Roma (Italy); Murphy, C. [School of Physics, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, Western Australia 6009 (Australia)

    2014-07-15

    A compact tilt accelerometer with high sensitivity at low frequency was designed to provide low frequency corrections for the feedback signal of the Advanced Laser Interferometer Gravitational Wave Observatory active seismic attenuation system. It has been developed using a Tungsten Carbide ceramic knife-edge hinge designed to avoid the mechanical 1/f noise believed to be intrinsic in polycrystalline metallic flexures. Design and construction details are presented; prototype data acquisition and control limitations are discussed. The instrument's characterization reported here shows that the hinge is compatible with being metal-hysteresis-free, and therefore also free of the 1/f noise generated by the dislocation Self-Organized Criticality in the metal. A tiltmeter of this kind will be effective to separate the ground tilt component from the signal of horizontal low frequency seismometers, and to correct the ill effects of microseismic tilt in advanced seismic attenuation systems.

  7. Monte Carlo modelling of germanium crystals that are tilted and have rounded front edges

    Energy Technology Data Exchange (ETDEWEB)

    Gasparro, Joel [EC-JRC-IRMM, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium); Hult, Mikael [EC-JRC-IRMM, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium)], E-mail: mikael.hult@ec.europa.eu; Johnston, Peter N. [Applied Physics, Royal Melbourne Institute of Technology, GPO Box 2476V, Melbourne 3001 (Australia); Tagziria, Hamid [EC-JRC-IPSC, Institute for the Protection and the Security of the Citizen, Via E. Fermi 1, I-21020 Ispra (Vatican City State, Holy See,) (Italy)

    2008-09-01

    Gamma-ray detection efficiencies and cascade summing effects in germanium detectors are often calculated using Monte Carlo codes based on a computer model of the detection system. Such a model can never fully replicate reality and it is important to understand how various parameters affect the results. This work concentrates on quantifying two issues, namely (i) the effect of having a Ge-crystal that is tilted inside the cryostat and (ii) the effect of having a model of a Ge-crystal with rounded edges (bulletization). The effect of the tilting is very small (in the order of per mille) when the tilting angles are within a realistic range. The effect of the rounded edges is, however, relatively large (5-10% or higher) particularly for gamma-ray energies below 100 keV.

  8. Monte Carlo modelling of germanium crystals that are tilted and have rounded front edges

    International Nuclear Information System (INIS)

    Gasparro, Joel; Hult, Mikael; Johnston, Peter N.; Tagziria, Hamid

    2008-01-01

    Gamma-ray detection efficiencies and cascade summing effects in germanium detectors are often calculated using Monte Carlo codes based on a computer model of the detection system. Such a model can never fully replicate reality and it is important to understand how various parameters affect the results. This work concentrates on quantifying two issues, namely (i) the effect of having a Ge-crystal that is tilted inside the cryostat and (ii) the effect of having a model of a Ge-crystal with rounded edges (bulletization). The effect of the tilting is very small (in the order of per mille) when the tilting angles are within a realistic range. The effect of the rounded edges is, however, relatively large (5-10% or higher) particularly for gamma-ray energies below 100 keV

  9. Coulomb Interaction Effect in Weyl Fermions with Tilted Energy Dispersion in Two Dimensions

    Science.gov (United States)

    Isobe, Hiroki; Nagaosa, Naoto

    2016-03-01

    Weyl fermions with tilted linear dispersions characterized by several different velocities appear in some systems including the quasi-two-dimensional organic semiconductor α -(BEDT -TTF )2I3 and three-dimensional WTe2 . The Coulomb interaction between electrons modifies the velocities in an essential way in the low-energy limit, where the logarithmic corrections dominate. Taking into account the coupling to both the transverse and longitudinal electromagnetic fields, we derive the renormalization group equations for the velocities of the tilted Weyl fermions in two dimensions, and found that they increase as the energy decreases and eventually hit the speed of light c to result in the Cherenkov radiation. Especially, the system restores the isotropic Weyl cone even when the bare Weyl cone is strongly tilted and the velocity of electrons becomes negative in certain directions.

  10. Design and initial characterization of a compact, ultra high vacuum compatible, low frequency, tilt accelerometer.

    Science.gov (United States)

    O'Toole, A; Peña Arellano, F E; Rodionov, A V; Shaner, M; Sobacchi, E; Dergachev, V; DeSalvo, R; Asadoor, M; Bhawal, A; Gong, P; Kim, C; Lottarini, A; Minenkov, Y; Murphy, C

    2014-07-01

    A compact tilt accelerometer with high sensitivity at low frequency was designed to provide low frequency corrections for the feedback signal of the Advanced Laser Interferometer Gravitational Wave Observatory active seismic attenuation system. It has been developed using a Tungsten Carbide ceramic knife-edge hinge designed to avoid the mechanical 1/f noise believed to be intrinsic in polycrystalline metallic flexures. Design and construction details are presented; prototype data acquisition and control limitations are discussed. The instrument's characterization reported here shows that the hinge is compatible with being metal-hysteresis-free, and therefore also free of the 1/f noise generated by the dislocation Self-Organized Criticality in the metal. A tiltmeter of this kind will be effective to separate the ground tilt component from the signal of horizontal low frequency seismometers, and to correct the ill effects of microseismic tilt in advanced seismic attenuation systems.

  11. Determination of the Optimal Tilt Angle for Solar Photovoltaic Panel in Ilorin, Nigeria

    Directory of Open Access Journals (Sweden)

    K.R. Ajao

    2013-06-01

    Full Text Available The optimal tilt angle of solar photovoltaic panel in Ilorin, Nigeria was determined. The solar panel was first mounted at 0o to the horizontal and after ten minutes, the voltage and current generated with the corresponding atmospheric temperature were recorded. The same procedure was repeated for 2o to 30o at a succession of 2o at ten minutes time interval over the entire measurement period. The result obtained shows that the average optimal tilt angle at which a solar panel will be mounted for maximum power performance at fixed position in Ilorin is 22o. This optimum angle of tilt of the solar panel and the orientation are dependent on the month of the year and the location of the site of study.

  12. Non-uniform-tilt-modulated fiber Bragg grating for temperature-immune micro-displacement measurement

    International Nuclear Information System (INIS)

    Guo, Tuan; Chen, Chengkun; Albert, Jacques

    2009-01-01

    Temperature-immune micro-displacement measurement is demonstrated by using a Gaussian-chirped tilted fiber Bragg grating (TFBG). The internal tilt angles of the sensing TFBG are effectively modulated via a displacement-induced Gaussian-strain-gradient along the specially designed bending cantilever beam. The phase mismatch between different effective pitches and tilt angles weakens the core-to-cladding mode coupling as the beam is displaced. While the power of the ghost mode resonance in transmission shows a strong sensitivity to the displacement, it is immune from spatially uniform temperature changes. Ghost-power-referenced displacement measurement and temperature-insensitive property are experimentally achieved for this cost-effective sensing device

  13. Profile relaxation and tilt instability in a field-reversed configuration

    International Nuclear Information System (INIS)

    Ohtani, H.; Horiuchi, R.; Sato, T.

    2003-01-01

    The profile relaxation from a magnetic hydrodynamic (MHD) profile to a kinetic equilibrium in field-reversed configurations (FRCs) is investigated by two-dimensional electromagnetic particle simulation. The radial oscillation takes place in order to relax an excess energy in the MHD profile, and the system spontaneously relaxes toward a kinetic equilibrium. In this kinetic equilibrium, the hollow electron current profile is realized as a result of the combined effects of the single particle orbits and the ion finite Larmor radius, and the ion current profile becomes peaked due to the effect of the ion meandering motion. Three-dimensional full electromagnetic particle simulation is also performed to study the stability of these kinetic equilibrium against the tilt mode. The growth rate of the tilt instability is reduced by the kinetic effects. It is found that the stabilization effect of tilt mode becomes much distinct when the current density changes from the peaked profile to the hollow one. (author)

  14. Experimental Investigation of the Performance of Tilt Current Meters in Wave-Dominated Flows

    DEFF Research Database (Denmark)

    Hansen, Asger Bendix; Carstensen, Stefan

    2017-01-01

    In recent years, tilt current meters (TCMs) have received renewed attention as they provide an inexpensive method for measuring currents in the coastal zone. However, previous studies focused mainly on current dominated flows or the current component of the flow. This study investigates the perfo......In recent years, tilt current meters (TCMs) have received renewed attention as they provide an inexpensive method for measuring currents in the coastal zone. However, previous studies focused mainly on current dominated flows or the current component of the flow. This study investigates...... TCMs were investigated in order to assess the effect of TCM shape on its performance. The measured TCM tilt is compared with the flow velocity measured by conventional methods. Furthermore, the ability of a TCM to measure wave orbital and wave-averaged velocities is discussed....

  15. Ambiguous Tilt and Translation Motion Cues in Astronauts after Space Flight

    Science.gov (United States)

    Clement, G.; Harm, D. L.; Rupert, A. H.; Beaton, K. H.; Wood, S. J.

    2008-01-01

    Adaptive changes during space flight in how the brain integrates vestibular cues with visual, proprioceptive, and somatosensory information can lead to impaired movement coordination, vertigo, spatial disorientation, and perceptual illusions following transitions between gravity levels. This joint ESA-NASA pre- and post-flight experiment is designed to examine both the physiological basis and operational implications for disorientation and tilt-translation disturbances in astronauts following short-duration space flights. The first specific aim is to examine the effects of stimulus frequency on adaptive changes in eye movements and motion perception during independent tilt and translation motion profiles. Roll motion is provided by a variable radius centrifuge. Pitch motion is provided by NASA's Tilt-Translation Sled in which the resultant gravitoinertial vector remains aligned with the body longitudinal axis during tilt motion (referred to as the Z-axis gravitoinertial or ZAG paradigm). We hypothesize that the adaptation of otolith-mediated responses to these stimuli will have specific frequency characteristics, being greatest in the mid-frequency range where there is a crossover of tilt and translation. The second specific aim is to employ a closed-loop nulling task in which subjects are tasked to use a joystick to null-out tilt motion disturbances on these two devices. The stimuli consist of random steps or sum-of-sinusoids stimuli, including the ZAG profiles on the Tilt-Translation Sled. We hypothesize that the ability to control tilt orientation will be compromised following space flight, with increased control errors corresponding to changes in self-motion perception. The third specific aim is to evaluate how sensory substitution aids can be used to improve manual control performance. During the closed-loop nulling task on both devices, small tactors placed around the torso vibrate according to the actual body tilt angle relative to gravity. We hypothesize

  16. Soft tilt and rotational modes in the hybrid improper ferroelectric Ca3Mn2O7

    Science.gov (United States)

    Glamazda, A.; Wulferding, D.; Lemmens, P.; Gao, B.; Cheong, S.-W.; Choi, K.-Y.

    2018-03-01

    Raman spectroscopy is employed to probe directly the soft rotation and tilting modes, which are two primary order parameters predicted in the hybrid improper ferroelectric material Ca3Mn2O7 . We observe a giant softening of the 107 -cm-1 octahedron tilting mode by 26 cm-1 on heating through the structural transition from a ferroelectric to paraelectric orthorhombic phase. This is contrasted by a small softening of the 150 -cm-1 rotational mode by 6 cm-1. In the intermediate phase, the competing soft modes with different symmetries coexist, bringing about many-faceted anomalies in spin excitations and lattice vibrations. Our work demonstrates that the soft rotation and tilt patterns, relying on a phase-transition path, are a key factor in determining ferroelectric, magnetic, and lattice properties of Ca3Mn2O7 .

  17. New insight on the dynamic of the Fontaine de Vaucluse karst hydrosystem from tilt measurements

    Science.gov (United States)

    Lesparre, Nolwenn; Boudin, Frédéric; Chéry, Jean; Champollion, Cédric; Danquigny, Charles; Seat, Han Cheng; Cattoen, Michel; Longuevergne, Laurent

    2016-04-01

    The deformation of natural systems in response to subsurface water storage and redistribution provides insights into the main water flow path within heterogeneous systems, including the role of faults or fractures. A long baseline tiltmeter was installed in the low-noise underground laboratory of Rustrel (LSBB) to study the response of the Fontaine de Vaucluse (FDV) karst hydrosystem to water cycle. Tilt data and piezometric levels recorded in a borehole close to the LSBB show a strong correlation with the discharge of the system observed at the FDV spring 30 km away. Over several months, tilt data were recorded on three base lines, thus allowing, for the first time, to study the tilt gradient variation that appears homogeneous. Such information provides a significant constraint on hydrological processes leading to the measured deformation. Several deformation models were tested using the ADELI code to estimate the type of hydro-mechanical structure that could reproduce the measured tilt and its gradient. On one hand, models show that uniform loading at the surface produces a much smaller signal than observed on measured data. On the other hand, the deformation related to the filling of a fracture following a precipitation event requires unrealistic fracture size. Finally, we found that a suitable hydro-mechanical model corresponds to the loading of numerous fractures at the interface between the saturated and unsaturated zones. Such a configuration predicts a tilt distribution in agreement with observations. This study suggests that tilt networks into a karst system should provide key observation for deciphering hydrological processes.

  18. [Evaluation of psychological fear in children undergoing head-up tilt test].

    Science.gov (United States)

    Chu, Wei-Hong; Wu, Li-Jia; Wang, Cheng; Lin, Ping; Li, Fang; Zhu, Li-Ping; Ran, Jing; Zou, Run-Mei; Liu, De-Yu

    2014-03-01

    To investigate the effects of different tilt angles of head-up tilt test (HUTT) and different responses to HUTT on the psychological fear in children undergoing the test. HUTT was performed on children with unexplained syncope or pre-syncope (107 cases: 52 males and 55 females), aged 5.5-17.8 years (mean 12.0±2.8 years). All subjects were randomly assigned to undergo HUTT at an angle of 60°, 70° or 80°; the negative cases underwent sublingual nitroglycerin-provocation HUTT at the same tilt angle. The Wong-Baker Faces Pain Rating Scale was used for self-assessment of psychological fear in subjects during HUTT at the end point of the test. The positive rate, hemodynamic changes and distribution of response types showed no significant differences between children at tilt angles of 60°, 70° and 80° (P>0.05). The greater the tilt angle, the higher the degree of psychological fear in children undergoing the test, but there were no significant differences between them (P>0.05). The degree of psychological fear in children who showed a positive response to HUTT (n=76) was significantly higher than that in children who showed a negative response (n=31) (Ppsychological fear in children undergoing the test, and the degree of psychological fear increases in children tested at tilt angles from 60° to 80°, but the differences have no statistical significance. A positive response to HUTT can significantly increase the psychological fear in children.

  19. Acute effects of head-down tilt and hypoxia on modulators of fluid homeostasis

    Science.gov (United States)

    Whitson, P. A.; Cintron, N. M.; Pietrzyk, R. A.; Scotto, P.; Loeppky, J. A.

    1994-01-01

    In an effort to understand the interaction between acute postural fluid shifts and hypoxia on hormonal regulation of fluid homeostasis, the authors measured the responses to head-down tilt with and without acute exposure to normobaric hypoxia. Plasma atrial natriuretic peptide (ANP), cyclic guanosine monophosphate (cGMP), cyclic adenosine monophosphate (cAMP), plasma aldosterone (ALD), and plasma renin activity (PRA) were measured in six healthy male volunteers who were exposed to a head-down tilt protocol during normoxia and hypoxia. The tilt protocol consisted of a 17 degrees head-up phase (30 minutes), a 28 degrees head-down phase (1 hour), and a 17 degrees head-up recovery period (2 hours, with the last hour normoxic in both experiments). Altitude equivalent to 14,828 ft was simulated by having the subjects breathe an inspired gas mixture with 13.9% oxygen. The results indicate that the postural fluid redistribution associated with a 60-minute head-down tilt induces the release of ANP and cGMP during both hypoxia and normoxia. Hypoxia increased cGMP, cAMP, ALD, and PRA throughout the protocol and significantly potentiated the increase in cGMP during head-down tilt. Hypoxia had no overall effect on the release of ANP, but appeared to attenuate the increase with head-down tilt. This study describes the acute effects of hypoxia on the endocrine response during fluid redistribution and suggests that the magnitude, but not the direction, of these changes with posture is affected by hypoxia.

  20. Finite Element Study of Implant Subsidence and Medial Tilt in Agility Ankle Replacement.

    Science.gov (United States)

    Cui, Yunwei; Hu, Pan; Wei, Ning; Cheng, Xiaodong; Chang, Wenli; Chen, Wei

    2018-02-23

    BACKGROUND Clinical studies indicate that in total ankle arthroplasty, postoperative implant subsidence and medial tilt become two significant concerns of the ankle replacement system, and which are associated with the contact between the bones and the talar component. Up to now, little attention has focused on the contact between the bones and the talar component. MATERIAL AND METHODS In order to address implant subsidence and medial tilt, one three-dimensional finite element model of contact between the bone and the talar components was built with the material properties of the cancellous bone interpolated from the experimental data, which represents variation of material properties through the cancellous bones. The finite element model was used to study the following: variation of the Young's modulus of the bones, stiffness of the talar component, loading direction, and loading magnitude with the implant subsidence. RESULTS The computational results reveal that a variety of Young's modulus of the cancellous bones causes the medial tilting of the talar component and that big plastic strains are associated with tilting. The implant subsidence increases from 0.169 mm to 0.269 mm when the loading changes from 272 kg to 408 kg. However, to the contrary, the implant subsidence decreases from 0.2676 mm to 0.1783 mm when Young's modulus of the bones increases 50%. However, the implant subsidence shows little change with a different Young's modulus of the talar component from 88 GPa to 132 GPa. CONCLUSIONS Our study indicates that a variety of different Young's modulus of the cancellous bones cause the medial tilting of the talar component. To solve subsidence and tilting, both the contact area and the variation of material properties should be taken into account.

  1. Optimizing pTILT perfusion imaging in the presence of off-resonance frequency.

    Science.gov (United States)

    Ouyang, Cheng; Sutton, Bradley P

    2013-07-01

    To optimize the perfusion measurements and to recover loss of tagging efficiency from the blood flow measurements in the presence of static field inhomogeneity with the pseudo-continuous arterial spin labeling technique of pTILT, which is sensitive to off-resonance effects due to the employment of concatenated radiofrequency (RF) pulses for labeling. Numerical Bloch simulations were performed to explore the labeling responses of concatenated RF pulses (45°, ±45°) in pTILT as a function of off-resonance frequency. A correction method was proposed by curve-fitting the measured blood flow signal to the signal model obtained from the simulations. The performance of the proposed correction method was examined for three healthy subjects on a 3 Tesla magnet after good shimming as well as under a "worst-case" scenario with deliberate mis-shimming. In cases after good shimming, in which the off-resonance frequency was less than 50 Hz, the perfusion measurements by the optimized pTILT sequence were improved by 12.7% compared with the original pTILT. With a "worst-case" mis-shimming and frequency offset by 80 Hz, the blood flow signal was increased by 68.9% and 64.8% for optimized global and localized pTILT, respectively. Addressing the impact of off-resonance frequency on concatenated RF pulses, tagging efficiency can be effectively recovered in pTILT perfusion measurements. This strategy may be extended to other applications of concatenated RF pulses where sensitivity to magnetic field inhomogeneity prevents accurate quantification. Copyright © 2013 Wiley Periodicals, Inc.

  2. Spatial Cognitive Performance During Adaptation to Conflicting Tilt-Translation Stimuli as a Sensorimotor Spaceflight Analog

    Science.gov (United States)

    Kayanickupuram, A. J.; Ramos, K. A.; Cordova, M. L.; Wood, S. J.

    2009-01-01

    The need to resolve new patterns of sensory feedback in altered gravitoinertial environments requires cognitive processes to develop appropriate reference frames for spatial orientation awareness. The purpose of this study was to examine deficits in spatial cognitive performance during adaptation to conflicting tilt-translation stimuli. Fourteen subjects were tilted within a lighted enclosure that simultaneously translated at one of 3 frequencies. Tilt and translation motion was synchronized to maintain the resultant gravitoinertial force aligned with the longitudinal body axis, resulting in a mismatch analogous to spaceflight in which the canals and vision signal tilt while the otoliths do not. Changes in performance on different spatial cognitive tasks were compared 1) without motion, 2) with tilt motion alone (pitch at 0.15, 0.3 and 0.6 Hz or roll at 0.3 Hz), and 3) with conflicting tilt-translation motion. The adaptation paradigm was continued for up to 30 min or until the onset of nausea. The order of the adaptation conditions were counter-balanced across 4 different test sessions. There was a significant effect of stimulus frequency on both motion sickness and spatial cognitive performance. Only 3 of 14 were able to complete the full 30 min protocol at 0.15 Hz, while 7 of 14 completed 0.3 Hz and 13 of 14 completed 0.6 Hz. There were no changes in simple visual-spatial cognitive tests, e.g., mental rotation or match-to-sample. There were significant deficits during 0.15 Hz adaptation in both accuracy and reaction time during a spatial reference task in which subjects are asked to identify a match of a 3D reoriented cube assemblage. Our results are consistent with antidotal reports of cognitive impairment that are common during sensorimotor adaptation with G-transitions. We conclude that these cognitive deficits stem from the ambiguity of spatial reference frames for central processing of inertial motion cues.

  3. Functional imaging of human extraocular muscles in head tilt dependent hypertropia.

    Science.gov (United States)

    Demer, Joseph L; Kung, Jennifer; Clark, Robert A

    2011-05-09

    Although alteration in hypertropia induced by head tilt is considered a clinical criterion for diagnosis of superior oblique (SO) palsy, the mechanism of this head-tilt-dependent hypertropia (HTDHT) is unclear. In this study, magnetic resonance imaging (MRI) was used to study extraocular muscle (EOM) responses to head tilt in HTDHT. Orbital MRI was used to study 16 normal subjects and 22 subjects with HTDT, of whom 12 had unilateral SO atrophy and 10 had "masquerading" SO palsy with normal SO size. Sizes and paths of all EOMs were compared in 90° roll tilts. Normal subjects exhibited the expected 3° to 7° physiologic extorsion of all four rectus pulleys in the orbit up-versus-down roll positions, corresponding to ocular counterrolling. In orbits with SO atrophy, the lateral (LR) and inferior rectus (IR) pulleys paradoxically intorted by approximately 2°. Subjects with HTDHT but normal SO size exhibited reduced or reversed extorsion of the medial, superior, and LR pulleys, whereas pulley shift was normal in nonhypertropic fellow orbits in HTDHT. In normal subjects and in SO atrophy, the inferior oblique (IO) muscle contracted in the orbit up-versus-down roll position, but paradoxically relaxed in HTDHT without SO atrophy. The ipsilesional IR and LR pulleys shift abnormally during head tilt in HTDHT with SO atrophy. In HTDHT without SO atrophy, the ipsilesional MR, SO, and LR pulleys shift abnormally, and the IO relaxes paradoxically during head tilt. These widespread alterations in EOM pulling directions suggest that complex neural adjustments to the otolith-ocular reflexes mediate HTDHT.

  4. Orthostatic intolerance in 6 degrees head-down tilt and lower body negative pressure loading

    Science.gov (United States)

    Yajima, Kazuyoshi; Miyamoto, Akira; Ito, Masao; Mano, Takaichi; Nakayama, Kiyoshi

    6 degrees head-down tilt bed rest experiment for 6 days was conducted at Nihon University Itabashi Hospital for 10 male athletes. In order to observe the orthostatic intolerance due to six days head-down tilt bed rest, 70 degrees head up tilt tests were performed before and after the head-down tilt. Two types of orthostatic intolerance were distinguished by the time course of their cardiovascular responses. One was vagotonia type and the other was brain anemia type. The latter type was commonly seen among astronauts after space flight due to the lack of plasma volume. As this volume change is considered to be initiated by some fluid loss from the lower extremities, analysis was made to clarify the relation between the leg volume change and the types of orthostatic intolerance. Nakayama proposed a Heart Rate Controllability Index, which is calculated from the initiate leg volume change and heart rate increase in head up tilt, for an indicator of the orthostatic intolerability. The index was applied to the subjects of six days head-down tilt above mentioned. For the subjects who showed a sign of presyncopy, the index values were higher or lower than that of the rest subjects who showed no sign of presyncopy. In order to evaluate the validity of the index, another experiment was conducted to induce an orthostatic intolerance by a different way of loading. The same types of orthostatic intolerance were observed and the index value hit high in the brain anemia type of orthostatic intolerance, while the vagotonia type showed relatively lower values than the normal group.

  5. The aurora at quite magnetospheric conditions: Repeatability and dipole tilt angle dependence

    International Nuclear Information System (INIS)

    Oznovich, I.; Eastes, R.W.; Huffman, R.E.; Tur, M.; Glaser, I.

    1993-01-01

    Is there a magnetospheric ground state? Do the position and size of the auroral oval depend on the magnetic dipole tilt angle at quiet magnetospheric conditions? In order to address these questions, northern hemisphere images of the aurora at 1356 Angstrom, obtained by Polar BEAR at solar minimum (beginning of 1987), were related to high temporal resolution IPM 8 measurements of the interplanetary magnetic field, to solar wind velocity, and to the ground-based activity index Kp. The first problem was addressed by a two-dimensional correlation study of the repeatability of auroral emissions in corrected geomagnetic space at conditions of minimum energy transfer from the magnetosphere. The correlation measure of auroral images was 0.6-0.85. Error simulations indicate that given the uncertainties in pixel position and intensity, the maximum expected value of the correlation measure is 0.65-0.9. The notion of a ground state magnetosphere is therefore supported by this data. Repeatability was found at the same level regardless of time or reconfigurations of the magnetosphere between images and independent of magnetic time sector. The second problem was addressed by relating latitudinal shifts of the aurora with dipole tilt angle without resorting to auroral boundary specification. This data indicate that the latitude of the continuous aurora is related to the dipole tilt angle at quiet magnetospheric conditions. In the winter hemisphere a 10 degrees increase in the dipole tilt angle causes a 1 degree decrease (increase) in the latitude of auroral emissions at noon (midnight). The magnetic local time distribution of the latitudinal shifts with dipole tilt angle support a simple model in which the dipole tilt angle determines the position of the center of the auroral circle along the magnetic meridian 1320-0120 MLT (for IMF B y positive) and does not affect its radius. 22 refs., 8 figs

  6. Incidence de la fluctuation des précipitations sur l'occupation des sols dans les hautes plaines de Sidi-Bel-Abbès (Algérie

    Directory of Open Access Journals (Sweden)

    Noreddine Letreuch-Belarouci

    2011-09-01

    Full Text Available La réduction de la pluviométrie dans les hautes plaines du sud de l'Algérie occidentale a provoqué de profondes modifications de l'occupation et de la gestion des espaces. L'activité économique de cette région est fortement conditionnée par les fluctuations climatiques et les modes traditionnels d'exploitation des surfaces agricoles. L'analyse de l'occupation actuelle des espaces et de sa dynamique permet d'appréhender les différentes contraintes appliquées à ces écosystèmes et de mesurer les incidences environnementales et sociales du changement climatique. L'objectif est de comprendre l'évolution des systèmes de production et de déterminer et maîtriser les paramètres qui influent sur leur dynamique pour une meilleure utilisation de ces espaces. L'incidence de la progression de l'aridité est perceptible à tous les niveaux : forte concentration de la population dans les centres urbains, réduction spatiale des formations végétales spontanées, augmentation des surfaces agricoles et de l'effectif du cheptel ovin menant la région vers un système de production agropastoral.Les hautes plaines de Sidi-Bel-Abbès sont impliquées dans tous les programmes de développement de la steppe. Elles se présentent comme une référence des régions du Sud Oranais et constituent, de ce fait, un espace idéal permettant de mesurer l'impact d'une politique d'aménagement ignorante des paramètres climatiques et de leurs fluctuations.The decline of rainfall in the highlands of the south-western Algeria has caused profound changes in occupation and management of areas. Economic activity in this region is strongly influenced by climatic fluctuations and traditional modes of exploitation of agricultural land. The analysis of the actual space occupancy and of its dynamics permits to understand the different stresses applied on these ecosystems and to measure the environmental and social impacts of climate change. The aim is to understand the

  7. Effects of rotor location, coning, and tilt on critical loads in large wind turbines

    Science.gov (United States)

    Spera, D. A.; Janetzke, D. C.

    1978-01-01

    Several large (1500 kW) horizontal rotor configurations were analyzed to determine the effects on dynamic loads of upwind downwind rotor locations, coned and radial blade positions, and tilted and horizontal rotor axis positions. Loads were calculated for a range of wind velocities at three locations in the structure: (1) the blade shank; (2) the hub shaft; and (3) the yaw drive. Blade axis coning and rotor axis tilt were found to have minor effects on loads. However, locating the rotor upwind of the tower significantly reduced loads at all locations analyzed.

  8. Effective wave tilt and surface impedance over a laterally inhomogeneous two-layer earth

    International Nuclear Information System (INIS)

    Hughes, W.J.; Wait, J.R.

    1975-01-01

    Using a perturbation method, the effect of a simple two-dimensional model on the electromagnetic fields at the surface of the Earth is considered for a postulated downcoming plane wave. The calculated change in the surface impedance and wave tilt due to lateral inhomogeneities is examined. It is found that the magnetic wave tilt (H/sub z//H/sub x/) is most seriously affected by such anomalies. This may have important consequences on electromagnetic probing of nonuniform portions of the Earth's crust

  9. Tilt-shift eddy current probe impact on information value of response signal

    Directory of Open Access Journals (Sweden)

    Chudacik Vladimir

    2016-03-01

    Full Text Available This article deals with the possibility for increasing of the informational value of a response signal using tilt-shift eddy current probe. Numerical simulations based on the FEM method using the OPERA 3D software as well as gained experimental results are presented. The simulated cracks are evaluated at the selected eddy current probe tilts and shifts with respect to conductive plate to obtain additional data needed for its evaluation and localization. Obtained simulation results are compared and discussed with the experimental results.

  10. The Transit Ingress and the Tilted Orbit of the Extraordinarily Eccentric Exoplanet HD 80606b

    Science.gov (United States)

    Winn, Joshua N.; Howard, Andrew W.; Johnson, John A.; Marcy, Geoffrey W.; Gazak, J. Zachary; Starkey, Donn; Ford, Eric B.; Colon, Knicole D.; Reyes, Francisco; Nortmann, Lisa; hide

    2009-01-01

    We reported the first detection of the transit ingress, revealing the transit duration to be 11.64 plus or minus 0.25 hr and allowing more robust determinations of the system parameters. Keck spectra obtained at midtransit exhibited an anomalous blueshift, giving definitive evidence that the stellar spin axis and planetary orbital axis are misaligned. Thus, the orbit of this planet is not only highly eccentric but is also tilted away from the equatorial plane of its parent star. A large tilt had been predicted, based on the idea that the planet's eccentric orbit was caused by the Kozai mechanism.

  11. Vector mode conversion based on tilted fiber Bragg grating in ring-core fibers

    Science.gov (United States)

    Mi, Yuean; Ren, Guobin; Gao, Yixiao; Li, Haisu; Zhu, Bofeng; Liu, Yu

    2018-03-01

    We propose a vector mode conversion approach based on tilted fiber Bragg grating (TFBG) written in ring-core fiber with effective separation of eigenmodes. The mode coupling properties of TFBG are numerically investigated. It is shown that under the constraint of phase matching, the conversion of high-order vector modes could be achieved at specific wavelengths. Moreover, the polarization of incident light and tilt angle of TFBG play critical roles in mode coupling process. The proposed TFBG provides an efficient method to realize high-order vector mode conversion, and it shows great potential for fibers based OAM beam generation and fiber lasers with vortex beams output.

  12. Analysis of the conoscopic measurement for uniaxial liquid-crystal tilt angles.

    Science.gov (United States)

    Van Horn, B L; Winter, H H

    2001-05-01

    Conoscopy as an optical method for accurate measurement of crystal tilt angles from interference figures is analyzed for the special case of uniaxial crystals. The displacement of interference figures is related to the crystal tilt angle in an explicit, noniterative manner that is accurate to within ~2%. The analysis applies to uniaxial nematic liquid-crystal monodomains and homogeneous crystals when a symmetrical center of the conoscopic interference figure is visible. The equations developed are also used to derive other previously reported expressions that are approximations with a limited range of applicability.

  13. Integrated single grating compressor for variable pulse front tilt in simultaneously spatially and temporally focused systems.

    Science.gov (United States)

    Block, Erica; Thomas, Jens; Durfee, Charles; Squier, Jeff

    2014-12-15

    A Ti:Al(3)O(2) multipass chirped pulse amplification system is outfitted with a single-grating, simultaneous spatial and temporal focusing (SSTF) compressor platform. For the first time, this novel design has the ability to easily vary the beam aspect ratio of an SSTF beam, and thus the degree of pulse-front tilt at focus, while maintaining a net zero-dispersion system. Accessible variation of pulse front tilt gives full spatiotemporal control over the intensity distribution at the focus and could lead to better understanding of effects such as nonreciprocal writing and SSTF-material interactions.

  14. Enhancing depth of focus in tilted microfluidics channels by digital holography.

    Science.gov (United States)

    Matrecano, Marcella; Paturzo, Melania; Finizio, Andrea; Ferraro, Pietro

    2013-03-15

    In this Letter we propose a method to enhance the limited depth of field (DOF) in optical imaging systems, through digital holography. The proposed approach is based on the introduction of a cubic phase plate into the diffraction integral, analogous to what occurs in white-light imaging systems. By this approach we show that it is possible to improve the DOF and to recover the extended focus image of a tilted object in a single reconstruction step. Moreover, we demonstrate the possibility of obtaining well-focused biological cells flowing into a tilted microfluidic channel.

  15. Improvement of image quality of holographic projection on tilted plane using iterative algorithm

    Science.gov (United States)

    Pang, Hui; Cao, Axiu; Wang, Jiazhou; Zhang, Man; Deng, Qiling

    2017-12-01

    Holographic image projection on tilted plane has an important application prospect. In this paper, we propose a method to compute the phase-only hologram that can reconstruct a clear image on tilted plane. By adding a constant phase to the target image of the inclined plane, the corresponding light field distribution on the plane that is parallel to the hologram plane is derived through the titled diffraction calculation. Then the phase distribution of the hologram is obtained by the iterative algorithm with amplitude and phase constrain. Simulation and optical experiment are performed to show the effectiveness of the proposed method.

  16. Exploring integral controllers in actively-lubricated tilting-pad journal bearings

    DEFF Research Database (Denmark)

    Salazar, Jorge Andrés González; Santos, Ilmar

    2015-01-01

    investigation of integral controllers for feedback-controlled lubrication with the aim of: a) presetting the static journal center and consequently exploring the changes of bearing dynamic properties; b) obtaining an integral controller capable of re-positioning the static journal eccentricity for matching......Active tilting-pad journal bearings with radial oil injection combine good stability properties of conventional tilting-pad journal bearings with the capability of improving their dynamic properties even more by control techniques. The main contribution of this work is the experimental...

  17. Quantum capacitance in topological insulators under strain in a tilted magnetic field

    KAUST Repository

    Tahir, M.

    2012-12-06

    Topological insulators exhibit unique properties due to surface states of massless Dirac fermions with conserved time reversal symmetry. We consider the quantum capacitance under strain in an external tilted magnetic field and demonstrate a minimum at the charge neutrality point due to splitting of the zeroth Landau level. We also find beating in the Shubnikov de Haas oscillations due to strain, which originate from the topological helical states. Varying the tilting angle from perpendicular to parallel washes out these oscillations with a strain induced gap at the charge neutrality point. Our results explain recent quantum capacitance and transport experiments.

  18. Frequency Response Analysis of an Actively Lubricated Rotor/Tilting-Pad Bearing System

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar

    2005-01-01

    In the present paper the dynamic response of a rotor supported by an active lubricated tilting-pad bearing is investigated in the frequency domain. The theoretical part of the investigation is based on a mathematical model obtained by means of rigid body dynamics. The oil film forces are inserted...... lubricated tilting-pad bearing. By applying a simple proportional controller it is possible to reach 30% reduction of the resonance peak associated with the first rigid body mode shape of the system. One of the most important consequences of such a vibration reduction in rotating machines is the feasibility...

  19. Impaired cerebral autoregulation during head up tilt in patients with severe brain injury

    DEFF Research Database (Denmark)

    Riberholt, Christian Gunge; Olesen, Niels Damkjær; Thing, Mira

    2016-01-01

    Early mobilization is of importance for improving long-term outcome for patients after severe acquired brain injury. A limiting factor for early mobilization by head-up tilt is orthostatic intolerance. The purpose of the present study was to examine cerebral autoregulation in patients with severe.......1 Hz spectral power in patients compared to healthy controls suggesting baroreflex dysfunction. In conclusion, patients with severe acquired brain injury and orthostatic intolerance during head-up tilt have impaired cerebral autoregulation more than one month after brain injury....

  20. Quantum capacitance in topological insulators under strain in a tilted magnetic field

    Science.gov (United States)

    Tahir, M.; Schwingenschlögl, U.

    2012-12-01

    Topological insulators exhibit unique properties due to surface states of massless Dirac fermions with conserved time reversal symmetry. We consider the quantum capacitance under strain in an external tilted magnetic field and demonstrate a minimum at the charge neutrality point due to splitting of the zeroth Landau level. We also find beating in the Shubnikov de Haas oscillations due to strain, which originate from the topological helical states. Varying the tilting angle from perpendicular to parallel washes out these oscillations with a strain induced gap at the charge neutrality point. Our results explain recent quantum capacitance and transport experiments.

  1. Cloning and characterization of a novel stress-responsive WRKY transcription factor gene (MusaWRKY71) from Musa spp. cv. Karibale Monthan (ABB group) using transformed banana cells.

    Science.gov (United States)

    Shekhawat, Upendra K Singh; Ganapathi, Thumballi R; Srinivas, Lingam

    2011-08-01

    WRKY transcription factor proteins play significant roles in plant stress responses. Here, we report the cloning and characterization of a novel WRKY gene, MusaWRKY71 isolated from an edible banana cultivar Musa spp. Karibale Monthan (ABB group). MusaWRKY71, initially identified using in silico approaches from an abiotic stress-related EST library, was later extended towards the 3' end using rapid amplification of cDNA ends technique. The 1299-bp long cDNA of MusaWRKY71 encodes a protein with 280 amino acids and contains a characteristic WRKY domain in the C-terminal half. Although MusaWRKY71 shares good similarity with other monocot WRKY proteins the substantial size difference makes it a unique member of the WRKY family in higher plants. The 918-bp long 5' proximal region determined using thermal asymmetric interlaced-polymerase chain reaction has many putative cis-acting elements and transcription factor binding motifs. Subcellular localization assay of MusaWRKY71 performed using a GFP-fusion platform confirmed its nuclear targeting in transformed banana suspension cells. Importantly, MusaWRKY71 expression in banana plantlets was up-regulated manifold by cold, dehydration, salt, ABA, H2O2, ethylene, salicylic acid and methyl jasmonate treatment indicating its involvement in response to a variety of stress conditions in banana. Further, transient overexpression of MusaWRKY71 in transformed banana cells led to the induction of several genes, homologues of which have been proven to be involved in diverse stress responses in other important plants. The present study is the first report on characterization of a banana stress-related transcription factor using transformed banana cells.

  2. Descripción morfoagronómica de materiales de plátano (Musa AAB, ABB y banano (Musa AAA cultivados en San Andrés Isla

    Directory of Open Access Journals (Sweden)

    Oscar Javier Parra Pachón

    2009-10-01

    Full Text Available Durante el primer semestre de 2005 se estudiaron los cultivares de plátano y banano en fincas y parcelas de 15 agricultores típicos participantes en programas conjuntos de la Secretaría de Agricultura y Pesca de San Andrés Isla y de la Universidad Nacional de Colombia sede Caribe. A partir de descriptores de INIBAP, IPGRI y CIRAD y revisiones bibliográficas.se describen morfológicamente los materiales de Musa cultivados en la Isla, así como las prácticas de los productores isleños, Se identificaron cuatro clones del subgrupo plátano (Musa AAB: un Hartón (‘Horse’ y tres Dominico-Hartón (‘Tallo Negro’, ‘Tallo Blanco’ y ‘Cincuenta’ del subgrupo ABB se hallaron un material de Bluggoe (‘Boscó’ y un Felipita. El subgrupo banano AAA presentó dos materiales Gros Michel (denominados Común y Chino y uno de banano (Rojo. El plátano tiene gran importancia para los agricultores de la Isla, siendo el Boscó el clon más aceptado entre consumidores por su adaptación a las condiciones edafológicas y climáticas. El banano es menos cultivado; ya que los suelos, el clima y las enfermedades como sigatoka negra, condicionaron el desarrollo de clones. El trabajo sugiere prácticas de fácil implementación que podrían aumentar la producción en los sistemas de huerto mixto tropical que predominan en la Isla.

  3. Descripción morfoagronómica de materiales de plátano (Musa AAB, ABB y banano (Musa AAA cultivados en San Andrés Isla

    Directory of Open Access Journals (Sweden)

    Parra Pachón Oscar Javier

    2009-12-01

    Full Text Available Durante el primer semestre de 2005 se estudiaron los cultivares de plátano y banano en fincas y parcelas de 15 agricultores típicos participantes en programas conjuntos de la Secretaría de Agricultura y Pesca de San Andrés Isla y de la Universidad Nacional de Colombia sede Caribe. A partir de descriptores de INIBAP, IPGRI y CIRAD y revisiones bibliográficas.se describen morfológicamente los materiales de Musa cultivados en la Isla, así como las prácticas de los productores isleños, Se identificaron cuatro clones del subgrupo plátano (Musa AAB: un Hartón (‘Horse’ y tres Dominico-Hartón (‘Tallo Negro’, ‘Tallo Blanco’ y ‘Cincuenta’ del subgrupo ABB se hallaron un material de Bluggoe (‘Boscó’ y un Felipita. El subgrupo banano AAA presentó dos materiales Gros Michel (denominados Común y Chino y uno de banano (Rojo. El plátano tiene gran importancia para los agricultores de la Isla, siendo el Boscó el clon más aceptado entre consumidores por su adaptación a las condiciones edafológicas y climáticas. El banano es menos cultivado; ya que los suelos, el clima y las enfermedades como sigatoka negra, condicionaron el desarrollo de clones. El trabajo sugiere prácticas de fácil implementación que podrían aumentar la producción en los sistemas de huerto mixto tropical que predominan en la Isla.

  4. A tilt-pair based method for assigning the projection directions of randomly oriented single-particle molecules.

    Science.gov (United States)

    Ueno, Yutaka; Mine, Shouhei; Kawasaki, Kazunori

    2015-04-01

    In this article, we describe an improved method to assign the projection angle for averaged images using tilt-pair images for three-dimensional reconstructions from randomly oriented single-particle molecular images. Our study addressed the so-called 'initial volume problem' in the single-particle reconstruction, which involves estimation of projection angles of the particle images. The projected images of the particles in different tilt observations were mixed and averaged for the characteristic views. After the ranking of these group average images in terms of reliable tilt angle information, mutual tilt angles between images are assigned from the constituent tilt-pair information. Then, multiples of the conical tilt series are made and merged to construct a network graph of the particle images in terms of projection angles, which are optimized for the three-dimensional reconstruction. We developed the method with images of a synthetic object and applied it to a single-particle image data set of the purified deacetylase from archaea. With the introduction of low-angle tilt observations to minimize unfavorable imaging conditions due to tilting, the results demonstrated reasonable reconstruction models without imposing symmetry to the structure. This method also guides its users to discriminate particle images of different conformational state of the molecule. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. Properties of the internal representation of gravity inferred from spatial-direction and body-tilt estimates.

    Science.gov (United States)

    Van Beuzekom, A D; Van Gisbergen, J A

    2000-07-01

    One of the key questions in spatial perception is whether the brain has a common representation of gravity that is generally accessible for various perceptual orientation tasks. To evaluate this idea, we compared the ability of six tilted subjects to indicate earth-centric directions in the dark with a visual and an oculomotor paradigm and to estimate their body tilt relative to gravity. Subjective earth-horizontal and -vertical data were collected, either by adjusting a visual line or by making saccades, at 37 roll-tilt angles across the entire range. These spatial perception responses and the associated body-tilt estimates were subjected to a principal-component analysis to describe their tilt dependence. This analysis allowed us to separate systematic and random errors in performance, to disentangle the effects of task (horizontal vs. vertical) and paradigm (visual vs. oculomotor) in the space-perception data, and to compare the veridicality of space perception and the sense of self-tilt. In all spatial-orientation tests, whether involving space-perception or body-tilt judgments, subjects made considerable systematic errors which mostly betrayed tilt underestimation [Aubert effect (A effect)] and peaked near 130 degrees tilt. However, the A effect was much smaller in body-tilt estimates than in spatial pointing, implying that the underlying signal processing must have been different. Pointing results obtained with the visual and the oculomotor paradigm were not identical either, but these differences, which were task-related (horizontal vs. vertical), were subtle in comparison. The tilt-dependent pattern of random errors (noisy scatter) was almost identical in visual and oculomotor pointing results, showing a steep monotonic increase with tilt angle, but was again clearly different in the body-tilt estimates. These findings are discussed in the context of a conceptual model in an attempt to explain how the different patterns of systematic and random errors in

  6. A dynamical systems approach to the tilted Bianchi models of solvable type

    Science.gov (United States)

    Coley, Alan; Hervik, Sigbjørn

    2005-02-01

    We use a dynamical systems approach to analyse the tilting spatially homogeneous Bianchi models of solvable type (e.g., types VIh and VIIh) with a perfect fluid and a linear barotropic γ-law equation of state. In particular, we study the late-time behaviour of tilted Bianchi models, with an emphasis on the existence of equilibrium points and their stability properties. We briefly discuss the tilting Bianchi type V models and the late-time asymptotic behaviour of irrotational Bianchi type VII0 models. We prove the important result that for non-inflationary Bianchi type VIIh models vacuum plane-wave solutions are the only future attracting equilibrium points in the Bianchi type VIIh invariant set. We then investigate the dynamics close to the plane-wave solutions in more detail, and discover some new features that arise in the dynamical behaviour of Bianchi cosmologies with the inclusion of tilt. We point out that in a tiny open set of parameter space in the type IV model (the loophole) there exist closed curves which act as attracting limit cycles. More interestingly, in the Bianchi type VIIh models there is a bifurcation in which a set of equilibrium points turns into closed orbits. There is a region in which both sets of closed curves coexist, and it appears that for the type VIIh models in this region the solution curves approach a compact surface which is topologically a torus.

  7. Performance Improvement of tilting-pad journal bearings by means of controllable lubrication

    DEFF Research Database (Denmark)

    Cerda, Alejandro; Santos, Ilmar

    2012-01-01

    for these mechanical devices, achieving nowadays an elasto-thermo-hydrodynamic formulation. On the other hand, the basic design of the Tilting-Pad Journal Bearing has been modified in order to transform it into a smart machine element. One approach to do so is to inject pressurized oil directly into the bearing...

  8. Spin-polarized radioactive isotope beam produced by tilted-foil technique

    International Nuclear Information System (INIS)

    Hirayama, Yoshikazu; Mihara, Mototsugu; Watanabe, Yutaka; Jeong, Sun-Chan; Miyatake, Hiroari; Momota, Sadao; Hashimoto, Takashi; Imai, Nobuaki; Matsuta, Kensaku; Ishiyama, Hironobu; Ichikawa, Shin-ichi; Ishii, Tetsuro; Izumikawa, Takuji; Katayama, Ichiro; Kawakami, Hirokane; Kawamura, Hirokazu; Nishinaka, Ichiro; Nishio, Katsuhisa; Makii, Hiroyuki; Mitsuoka, Shin-ichi

    2013-01-01

    Highlights: • Detail study for tilted foil technique. • New equation for estimating nuclear polarization dependence on the beam energy. • Production of nuclear polarization for heaviest nucleus 123 In in ground state. -- Abstract: The tilted-foil method for producing spin-polarized radioactive isotope beams has been studied using the re-accelerated radioactive 8 Li and 123 In beams produced at Tokai Radioactive Ion Accelerator Complex (TRIAC) facility. We successfully produced polarization in a 8 Li beam of 7.3(5)% using thin polystyrene foils (4.2 μg/cm 2 ). The systematic study of the nuclear polarization as a function of the number of foils and beam energy has been performed, confirming the features of the tilted-foil technique experimentally. After the study, a spin-polarized radioactive 123 In beam, which is the heaviest ever polarized in its ground state by this method, has been successfully generated by the tilted-foil method, for the nuclear spectroscopy around the doubly magic nucleus 132 Sn

  9. Human cutaneous vascular responses to whole-body tilting, Gz centrifugation, and LBNP

    Science.gov (United States)

    Watenpaugh, Donald E.; Breit, Gregory A.; Buckley, Theresa M.; Ballard, Richard E.; Murthy, Gita; Hargens, Alan R.

    2004-01-01

    We hypothesized that gravitational stimuli elicit cardiovascular responses in the following order with gravitational stress equalized at the level of the feet, from lowest to highest response: short-(SAC) and long-arm centrifugation (LAC), tilt, and lower body negative pressure (LBNP). Up to 15 healthy subjects underwent graded application of the four stimuli. Laser-Doppler flowmetry measured regional skin blood flow. At 0.6 G(z) (60 mmHg LBNP), tilt and LBNP similarly reduced leg skin blood flow to approximately 36% of supine baseline levels. Flow increased back toward baseline levels at 80-100 mmHg LBNP yet remained stable during 0.8-1.0 G(z) tilt. Centrifugation usually produced less leg vasoconstriction than tilt or LBNP. Surprisingly, SAC and LAC did not differ significantly. Thigh responses were less definitive than leg responses. No gravitational vasoconstriction occurred in the neck. All conditions except SAC increased heart rate, according to our hypothesized order. LBNP may be a more effective and practical means of simulating cardiovascular effects of gravity than centrifugation.

  10. Circadian blood pressure and systemic haemodynamics during 42 days of 6 degrees head-down tilt

    NARCIS (Netherlands)

    Voogel, A. J.; Stok, W. J.; Pretorius, P. J.; van Montfrans, G. A.; Langewouters, G. J.; Karemaker, J. M.

    1997-01-01

    Head-down tilted bedrest is a ground-based microgravity simulation model. Since in this position the influence of chief external determinants of circadian blood pressure variation, i.e. activity and posture, are reduced, it may reveal endogenous oscillatory factors. The effects of 42 days of 6

  11. Application of computer vision in studying fire plume behavior of tilting flames

    Science.gov (United States)

    Aminfar, Amirhessam; Cobian Iñiguez, Jeanette; Pham, Stephanie; Chong, Joey; Burke, Gloria; Weise, David; Princevac, Marko

    2016-11-01

    With the development in computer sciences especially in the field of computer vision, image processing has become an inevitable part of flow visualization. Computer vision can be used to visualize flow structure and to quantify its properties. We used a computer vision algorithm to study fire plume tilting when the fire is interacting with a solid wall. As the fire propagates to the wall the amount of air available for the fire to consume will decrease on the wall side. Therefore, the fire will start tilting towards the wall. Aspen wood was used for the fuel source and various configurations of the fuel were investigated. The plume behavior was captured using a digital camera. In the post processing, the flames were isolated from the image by using edge detection technics, making it possible to develop an algorithm to calculate flame height and flame orientation. Moreover, by using an optical flow algorithm we were able to calculate the speed associated with the edges of the flame which is related to the flame propagation speed and effective vertical velocity of the flame. The results demonstrated that as the size of the flame was increasing, the flames started tilting towards the wall. Leading to the conclusion that there should be a critical area of fire in which the flames start to tilt. Also, the algorithm made it possible to calculate a critical distance in which the flame will start orienting towards the wall

  12. Combining periodic hydraulic tests and surface tilt measurements to explore in situ fracture hydromechanics

    Science.gov (United States)

    Schuite, Jonathan; Longuevergne, Laurent; Bour, Olivier; Guihéneuf, Nicolas; Becker, Matthew W.; Cole, Matthew; Burbey, Thomas J.; Lavenant, Nicolas; Boudin, Frédéric

    2017-08-01

    Fractured bedrock reservoirs are of socio-economical importance, as they may be used for storage or retrieval of fluids and energy. In particular, the hydromechanical behavior of fractures needs to be understood as it has implications on flow and governs stability issues (e.g., microseismicity). Laboratory, numerical, or field experiments have brought considerable insights to this topic. Nevertheless, in situ hydromechanical experiments are relatively uncommon, mainly because of technical and instrumental limitations. Here we present the early stage development and validation of a novel approach aiming at capturing the integrated hydromechanical behavior of natural fractures. It combines the use of surface tiltmeters to monitor the deformation associated with the periodic pressurization of fractures at depth in crystalline rocks. Periodic injection and withdrawal advantageously avoids mobilizing or extracting significant amounts of fluid, and it hinders any risk of reservoir failure. The oscillatory perturbation is intended to (1) facilitate the recognition of its signature in tilt measurements and (2) vary the hydraulic penetration depth in order to sample different volumes of the fractured bedrock around the inlet and thereby assess scale effects typical of fractured systems. By stacking tilt signals, we managed to recover small tilt amplitudes associated with pressure-derived fracture deformation. Therewith, we distinguish differences in mechanical properties between the three tested fractures, but we show that tilt amplitudes are weakly dependent on pressure penetration depth. Using an elastic model, we obtain fracture stiffness estimates that are consistent with published data. Our results should encourage further improvement of the method.

  13. Leedu nõuab Eestilt ja Lätilt tuumaõnnetuse puhuks tagatist / Andrus Karnau

    Index Scriptorium Estoniae

    Karnau, Andrus

    2007-01-01

    Erimeelsustest Ignalina uue tuumajaama partnerite vahel. Leedu nõuab Eestilt ja Lätilt osalemist tuumajäätmete matmisel ja võimalike õnnetuste tagajärgede likvideerimisel, Poola soovib Ignalina uues reaktoris Balti riikidega võrdset osalust. Lisa: Ignalina uus reaktor

  14. Shape evolution in 76, 78Kr nuclei at high spins in tilted axis ...

    Indian Academy of Sciences (India)

    A two-dimensional tilted axis cranking Hartree–Fock–Bogoliubov (CHFB) calculation is performed for 76Kr and 78Kr nuclei up to high spins = 30 employing a pairing-plus-quadrupole (PPQ) model interaction Hamiltonian. Intricate details of the evolution of single particle structures and shapes as a function of spin have ...

  15. Hydraulic design of a tilting weir allowing for periodic fish migration

    NARCIS (Netherlands)

    Hoitink, A.J.F.; Dommerholt, A.; Gerven, van L.P.A.

    2008-01-01

    The hydraulic design of a tilting weir is presented, which allows for periodic exchange of potadromous fish between freshwater ecosystems. The application domain includes inland waters that need to be isolated hydraulically, preserving the existing ecological connection with the surrounding areas as

  16. The cone phase of liquid crystals: Triangular lattice of double-tilt ...

    Indian Academy of Sciences (India)

    physics pp. 277–283. The cone phase of liquid crystals: Triangular lattice of double-tilt cylinders. YASHODHAN HATWALNE and N V MADHUSUDANA. Raman Research Institute, C. V. ..... [19] D R Nelson, in Observation, prediction and simulation of phase transitions in complex fluids edited by M Baus, L F Rull and J-P ...

  17. Scanning transmission electron microscopy through-focal tilt-series on biological specimens.

    Science.gov (United States)

    Trepout, Sylvain; Messaoudi, Cédric; Perrot, Sylvie; Bastin, Philippe; Marco, Sergio

    2015-10-01

    Since scanning transmission electron microscopy can produce high signal-to-noise ratio bright-field images of thick (≥500 nm) specimens, this tool is emerging as the method of choice to study thick biological samples via tomographic approaches. However, in a convergent-beam configuration, the depth of field is limited because only a thin portion of the specimen (from a few nanometres to tens of nanometres depending on the convergence angle) can be imaged in focus. A method known as through-focal imaging enables recovery of the full depth of information by combining images acquired at different levels of focus. In this work, we compare tomographic reconstruction with the through-focal tilt-series approach (a multifocal series of images per tilt angle) with reconstruction with the classic tilt-series acquisition scheme (one single-focus image per tilt angle). We visualised the base of the flagellum in the protist Trypanosoma brucei via an acquisition and image-processing method tailored to obtain quantitative and qualitative descriptors of reconstruction volumes. Reconstructions using through-focal imaging contained more contrast and more details for thick (≥500 nm) biological samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Equivalences from tilting theory and commutative algebra from the adjoint functor point of view

    DEFF Research Database (Denmark)

    Celikbas, Olgur; Holm, Henrik

    2017-01-01

    We give a category theoretic approach to several known equivalences from (classic) tilting theory and commutative algebra. Furthermore, we apply our main results to establish a duality theory for relative Cohen Macaulay modules in the sense of Hellus, Schenzel, and Z argar....

  19. An iterative fast sweeping based eikonal solver for tilted orthorhombic media

    KAUST Repository

    Waheed, Umair bin

    2014-08-01

    Computing first-arrival traveltimes of quasi-P waves in the presence of anisotropy is important for high-end near-surface modeling, microseismic-source localization, and fractured-reservoir characterization, and requires solving an anisotropic eikonal equation. Anisotropy deviating from elliptical anisotropy introduces higher-order nonlinearity into the eikonal equation, which makes solving the eikonal equation a challenge. We address this challenge by iteratively solving a sequence of simpler tilted elliptically anisotropic eikonal equations. At each iteration, the source function is updated to capture the effects of the higher order nonlinear terms. We use Aitken extrapolation to speed up the convergence rate of the iterative algorithm. The result is an algorithm for first-arrival traveltime computations in tilted anisotropic media. We demonstrate our method on tilted transversely isotropic media and tilted orthorhombic media. Our numerical tests demonstrate that the proposed method can match the first arrivals obtained by wavefield extrapolation, even for strong anisotropy and complex structures. Therefore, for the cases where oneor two-point ray tracing fails, our method may be a potential substitute for computing traveltimes. Our approach can be extended to anisotropic media with lower symmetries, such as monoclinic or even triclinic media.

  20. An iterative, fast-sweeping-based eikonal solver for 3D tilted anisotropic media

    KAUST Repository

    Waheed, Umair bin

    2015-03-30

    Computation of first-arrival traveltimes for quasi-P waves in the presence of anisotropy is important for high-end near-surface modeling, microseismic-source localization, and fractured-reservoir characterization - and it requires solving an anisotropic eikonal equation. Anisotropy deviating from elliptical anisotropy introduces higher order nonlinearity into the eikonal equation, which makes solving the eikonal equation a challenge. We addressed this challenge by iteratively solving a sequence of simpler tilted elliptically anisotropic eikonal equations. At each iteration, the source function was updated to capture the effects of the higher order nonlinear terms. We used Aitken\\'s extrapolation to speed up convergence rate of the iterative algorithm. The result is an algorithm for computing first-arrival traveltimes in tilted anisotropic media. We evaluated the applicability and usefulness of our method on tilted transversely isotropic media and tilted orthorhombic media. Our numerical tests determined that the proposed method matches the first arrivals obtained by wavefield extrapolation, even for strongly anisotropic and highly complex subsurface structures. Thus, for the cases where two-point ray tracing fails, our method can be a potential substitute for computing traveltimes. The approach presented here can be easily extended to compute first-arrival traveltimes for anisotropic media with lower symmetries, such as monoclinic or even the triclinic media.

  1. Relationship Between Anterior Lamina Cribrosa Surface Tilt and Glaucoma Development in Myopic Eyes.

    Science.gov (United States)

    Lee, Eun Jung; Han, Jong Chul; Kee, Changwon

    2017-05-01

    To evaluate the anterior lamina cribrosa (LC) surface tilt angle in myopic eyes and associate it with glaucoma development. In this retrospective study, medical records of myopic patients referred for glaucoma examination from July 1, 2012 to March 30, 2016 were reviewed. Comprehensive ophthalmic examination including spectral-domain optical coherence tomography were performed. We measured the angle of anterior LC surface tilt against Bruch's membrane opening from optical coherence tomography images at the center of the clinical optic disc margin. In horizontal and vertical sections, the angles were defined as α and β, respectively. Patients were grouped according to the presence of glaucomatous damage and factors including optic nerve head morphologic parameters and LC tilt angles were compared between the 2 groups. Among 138 patients originally enrolled, 102 patients were finally analyzed. One eye from 1 patient was randomly chosen. Fifty-five eyes had glaucoma and 47 were normal. The degree of myopia and all optic nerve head morphologic parameters were not significantly different between the 2 groups. However, |α| and |β| were significantly larger in the glaucoma group (all Pglaucoma in normal-pressure myopic eyes. Angulation of the LC against Bruch's membrane opening plane might be associated with increased glaucoma susceptibility in myopic eyes. Further investigations are warranted before clinical utilization of LC tilt as glaucoma susceptibility biomarker.

  2. Functional alignments and self-tests for tilted and decentered optics

    International Nuclear Information System (INIS)

    Bauke, W.; Cross, E.W.

    1983-01-01

    The alignment of tilted and decentered optics is ordinarily difficult, because such optics have neither simple alignment points amenable to ordinary boresight methods, nor a simple alignment theory. Several different alignment examples which provide insight into a practical universal approach to all such systems are explored. The examples detailed are segments of the Antares Laser Fusion Project's optical train

  3. The dynamic behaviour of man-wide vehicles with an automatic active tilting mechanism

    NARCIS (Netherlands)

    Pauwelussen, J.P.

    1999-01-01

    The major advantage of a motorcycle with respect to a passenger car is the possibility of the driver to tilt during cornering and thereby maintaining stability whereas a passenger car will suffer from the risk of capsizing at high speed. This observation has lead Brink Dynamics to create and develop

  4. Tilted Bianchi Type III Wet Dark Fluid Cosmological Model in Saez and Ballester Theory

    Science.gov (United States)

    Sahu, Subrata Kumar; Kantila, Endale Nigatu; Gebru, Dawit Melese

    2016-01-01

    Tilted Bianchi-III wet dark fluid cosmological model is investigated in the frame work of Saez and Ballester theory (Phys. Lett. A. 113:467, 1986). Exact solutions to the field equations are derived when the metric potentials are functions of cosmic time only. Some physical and geometrical properties of the solutions are also discussed.

  5. Effect of radiation on convective flow in a tilted solar collector filled ...

    African Journals Online (AJOL)

    user

    Keywords: Radiation, tilted solar collector, finite element method, water- alumina nanofluid. ... instead of conventional heat transfer fluids (like water). The poor heat transfer properties ... to suspend ultra fine solid particles in the fluid for improving the thermal conductivity of the fluid Hetsroni and Rozenblit (1994). These early ...

  6. Optimal Tilt Angle and Orientation of Photovoltaic Modules Using HS Algorithm in Different Climates of China

    Directory of Open Access Journals (Sweden)

    Mian Guo

    2017-10-01

    Full Text Available Solar energy technologies play an important role in shaping a sustainable energy future, and generating clean, renewable, and widely distributed energy sources. This paper determines the optimum tilt angle and optimum azimuth angle of photovoltaic (PV panels, employing the harmony search (HS meta-heuristic algorithm. In this study, the ergodic method is first conducted to obtain the optimum tilt angle and the optimum azimuth angle in several cities of China based on the model of Julian dating. Next, the HS algorithm is applied to search for the optimum solution. The purpose of this research is to maximize the extraterrestrial radiation on the collector surface for a specific period. The sun’s position is predicted by the proposed model at different times, and then solar radiation is obtained on various inclined planes with different orientations in each city. The performance of the HS method is compared with that of the ergodic method and other optimization algorithms. The results demonstrate that the tilt angle should be changed once a month, and the best orientation is usually due south in the selected cities. In addition, the HS algorithm is a practical and reliable alternative for estimating the optimum tilt angle and optimum azimuth angle of PV panels.

  7. A transversely isotropic medium with a tilted symmetry axis normal to the reflector

    KAUST Repository

    Alkhalifah, Tariq Ali

    2010-05-01

    The computational tools for imaging in transversely isotropic media with tilted axes of symmetry (TTI) are complex and in most cases do not have an explicit closed-form representation. Developing such tools for a TTI medium with tilt constrained to be normal to the reflector dip (DTI) reduces their complexity and allows for closed-form representations. The homogeneous-case zero-offset migration in such a medium can be performed using an isotropic operator scaled by the velocity of the medium in the tilt direction. For the nonzero-offset case, the reflection angle is always equal to the incidence angle, and thus, the velocities for the source and receiver waves at the reflection point are equal and explicitly dependent on the reflection angle. This fact allows for the development of explicit representations for angle decomposition as well as moveout formulas for analysis of extended images obtained by wave-equation migration. Although setting the tilt normal to the reflector dip may not be valid everywhere (i.e., on salt flanks), it can be used in the process of velocity model building, in which such constrains are useful and typically are used. © 2010 Society of Exploration Geophysicists.

  8. Tilted Kantowski-Sachs cosmological model in Brans-Dicke theory of gravitation

    Science.gov (United States)

    Pawar, D. D.; Shahare, S. P.; Dagwal, V. J.

    2018-02-01

    Tilted Kantowski-Sachs cosmological model in Brans-Dicke theory for perfect fluid has been investigated. The general solution of field equations in Brans-Dicke theory for the combined scalar and tensor field are obtained by using power law relation. Also, some physical and geometrical parameters are obtained and discussed.

  9. Cognitive suppression of tilt sensations during linear horizontal ego-motion in the dark

    NARCIS (Netherlands)

    Wertheim, A.H.; Mesland, B.S.; Bles, W.

    2001-01-01

    On the basis of models of otolith functioning, one would expect that, during sinusoidal linear self-motion in darkness, percepts of body tilt are experienced. However, this is normally not the case, which suggests that the otoliths are not responsive to small deviations from the vertical of the

  10. Impact of mechanical down tilt and height on the pilot coverage of ...

    African Journals Online (AJOL)

    The task of planning a network can be very challenging as it involves many careful studies with a lot of considerations and, at times, trial and error. In this paper, the impacts of antenna mechanical down tilt and antenna height on UMTS network performance are studied. First, we used ASSET3G simulation software to design ...

  11. PVC stay-in-place panel covers for tilt-up and pre-cast construction

    OpenAIRE

    ECT Team, Purdue

    2012-01-01

    Octaform™ stay-in-place concrete forming system is PVC insulated concrete form system. These forms have been used in the industry for various applications to improve the insulation and corrosion resistance of structures. Octaform™ has developed the panel covers so the advantages of PVC stay-in-place concrete forming systems could be applied to tilt-up and pre-cast construction.

  12. Optimal design of Tilting-Pad Thrust Bearings with High Pressure Injection Pockets

    DEFF Research Database (Denmark)

    Heinrichson, Niels; Santos, Ilmar

    2006-01-01

    A thermo-elasto-hydrodynamic(TEHD) model based on the Reynolds equation has been used to study the effect of oil injection pockets on the performance of tilting pad thrust bearings. The optimal position of the pivot both with respect to load carrying capacity and minimal power consumption is seen...

  13. A single-layer tilting actuator with multiple close-gap electrodes

    International Nuclear Information System (INIS)

    Shmilovich, T; Krylov, S

    2009-01-01

    We report on the design, fabrication and characterization of a novel tilting electrostatic actuator, fabricated by using a single layer of a silicon on insulator (SOI) wafer and investigate, both theoretically and experimentally, the electromechanical behavior of the device. The actuator incorporates high aspect ratio comb-like electrodes oriented in the direction parallel to the rotation axis of the tilting element. An increase in the tilting angle is accompanied by a decrease in the distance between the electrodes and by an increase of the actuating torque. Simultaneously, the overlap area between electrodes located farther apart the axis shrinks, resulting in a 'restoring' torque in the opposite direction. The electromechanical behavior and stability of the device were investigated using a simplified model of the actuator and verified by a coupled three-dimensional simulation. Model results suggest that by changing the design parameters, the actuator characteristic can be tailored in a large range. Devices of three different configurations incorporating elastic torsion axes or bending flexures were fabricated and characterized and both static and resonant responses, typical for parametrically excited nonlinear oscillators, were registered. Theoretical and experimental results indicate that the suggested architecture can be efficiently used for the static and dynamic operation of electrostatic tilting devices

  14. Tilted Dirac Cone Effect on Interlayer Magnetoresistance in α-(BEDT-TTF)2I3

    Science.gov (United States)

    Tajima, Naoya; Morinari, Takao

    2018-04-01

    We report the effect of Dirac cone tilting on interlayer magnetoresistance in α-(BEDT-TTF)2I3, which is a Dirac semimetal under pressure. Fitting of the experimental data by the theoretical formula suggests that the system is close to a type-II Dirac semimetal.

  15. An Online Tilt Estimation and Compensation Algorithm for a Small Satellite Camera

    Science.gov (United States)

    Lee, Da-Hyun; Hwang, Jai-hyuk

    2018-04-01

    In the case of a satellite camera designed to execute an Earth observation mission, even after a pre-launch precision alignment process has been carried out, misalignment will occur due to external factors during the launch and in the operating environment. In particular, for high-resolution satellite cameras, which require submicron accuracy for alignment between optical components, misalignment is a major cause of image quality degradation. To compensate for this, most high-resolution satellite cameras undergo a precise realignment process called refocusing before and during the operation process. However, conventional Earth observation satellites only execute refocusing upon de-space. Thus, in this paper, an online tilt estimation and compensation algorithm that can be utilized after de-space correction is executed. Although the sensitivity of the optical performance degradation due to the misalignment is highest in de-space, the MTF can be additionally increased by correcting tilt after refocusing. The algorithm proposed in this research can be used to estimate the amount of tilt that occurs by taking star images, and it can also be used to carry out automatic tilt corrections by employing a compensation mechanism that gives angular motion to the secondary mirror. Crucially, this algorithm is developed using an online processing system so that it can operate without communication with the ground.

  16. Comparison of acute cardiovascular responses to water immersion and head-down tilt in humans

    DEFF Research Database (Denmark)

    Shiraishi, Makoto; Schou, Morten; Gybel, Mikkel

    2002-01-01

    The hypothesis was tested that acute water immersion to the neck (WI) compared with 6 degrees head-down tilt (HDT) induces a more pronounced distension of the heart and lower plasma levels of vasoconstrictor hormones. Ten healthy males underwent 30 min of HDT, WI, and a seated control (randomized...

  17. Rat cardiovascular responses to whole body suspension - Head-down and non-head-down tilt

    Science.gov (United States)

    Musacchia, X. J.; Steffen, Joseph M.; Dombrowski, Judy

    1992-01-01

    Two experiments aimed at examining the versatility of the whole body suspension (WBS) system as a ground-based model for cardiovascular effects of microgravity are described. The first experiment studied heart rate and arterial pressure responses in rats during a 7-day period of head-down tilt (HDT) or nonhead-down tilt (NHDT) and after removal from whole body suspension (WBS). Mean arterial (MAP), systolic, and diastolic pressures increased about 20 percent in HDT rats on the fist day, heart rates were elevated about 10 percent. During postsuspension most cardiovascular parameters returned to presuspension levels. The second experiment evaluated responses to rapid head-up tilt in HDT and NHDT rats. It was observed that, while pulse pressures remained unchanged, MAP, systolic and diastolic pressures, and HR were elevated in HDT and NHDT rats during head-up tilt after one day of suspension. The WBS rats are considered to be useful as a model to better understand responses of rats exposed to microgravity.

  18. How to program pulse duration or tilt in implantable cardioverter defibrillators.

    Science.gov (United States)

    Irnich, Werner

    2003-01-01

    Implantable cardioverter defibrillators (ICDs) are available with independently programmable duration and tilt of the shock pulse waveform. Manufacturers do not, however, commonly advise how these parameters can be programmed for optimal clinical benefit. From theoretical considerations, the author recommends programming both parameters based on the measured lead system resistance R into which the shock is delivered. Assuming that the defibrillation pulse decline below the defibrillation threshold rheobase is undesirable because of the possibility of refibrillation. Mathematical relationships expressing optimal pulse duration and tilt as functions of the output time constant can be derived that are valid for monophasic pulses and the first phase of biphasic pulses. Two ICD manufacturers provide for programmable tilt (Medtronic GEM III, atrial channel) or both tilt T and pulse duration PD. (St. Jude Medical newest devices). Considering its output capacitance, it is recommended that the Medtronic Gem III should be programmed for T = 50% when R defibrillation, but it is suggested that this can best be accomplished by programming these parameters with the guidance of theory as described in this discussion.

  19. Technical note: a tool for determining rotational tilt axis with or without fiducial markers.

    Science.gov (United States)

    Kobayashi, Atsuko; Fujigaya, Takumi; Itoh, Masayuki; Taguchi, Takahisa; Takano, Hiroshi

    2009-12-01

    Virtually all reliable TEM tomographic reconstructions in life science depend upon cross-correlating successive images in a tilt-stack, and then using gold nanobeads as fiducial markers for determining the relative image rotation axis. Although the rotational tilt angle is one of the essential parameters affecting the quality of tomographic reconstructions, little is discussed about its determination. We provide here a simple tool based on the property of Fast Fourier Transformation for determining this rotation axis offset angle. Our method uses two publicly-available software packages (IMOD and ImageJ), and can be used on any TEM-based image stack, which is useful for images with poor bead distribution or situations where such beads are not visible. We illustrate this procedure with two different biological samples, one of which is a plunge frozen cryo-sample with fiducials and the other an epon-embedded thin section without fiducials. Prior knowledge of the rotational tilt angle facilitates further processing tomograms. With cross-correlation and the FFT-obtained rotational tilt angle, we reconstructed tomograms, of which the cross-section did not show "arc" distortion. This tool could be easily incorporated into any software for the alignment with or without fiducials.

  20. Tilted Bianchi type I dust fluid cosmological model in general relativity

    Indian Academy of Sciences (India)

    Abstract. In this paper, we have investigated a tilted Bianchi type I cosmological model filled with dust of perfect fluid in general relativity. To get a determinate solution, we have assumed a condition. A. Bn between metric potentials. The physical and geometrical aspects of the model together with singularity in the model are ...

  1. Active tilting-pad journal bearings supporting flexible rotors: Part I – The hybrid lubrication

    DEFF Research Database (Denmark)

    Salazar, Jorge Andrés González; Santos, Ilmar

    2017-01-01

    This is part I of a twofold paper series, of theoretical and experimental nature, presenting the design and implementation of model-based controllers meant for assisting the hybrid and developing the feedback-controlled lubrication regimes in active tilting-pad journal bearings (active TPJBs). In...

  2. Exploring a possible origin of a 14 deg y-normal spin tilt at RHIC polarimeter

    Energy Technology Data Exchange (ETDEWEB)

    Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Huang, H. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-06-15

    A possible origin of a 14 deg y-normal spin n0 tilt at the polarimeter is in snake angle defects. This possible cause is investigated by scanning the snake axis angle µ, and the spin rotation angle at the snake, φ, in the vicinity of their nominal values.

  3. The Trapping of Helium at a Low Angle Tilt Boundary in Molybdenum

    NARCIS (Netherlands)

    Evans, J.H.; Veen, A. van; Hosson, J.Th.M. De; Bullough, R.; Willis, J.R.

    1984-01-01

    This paper presents experimental evidence of helium trapping at a set of b = [100] edge dislocations defining a low angle tilt boundary in molybdenum together with theoretical results on two aspects of helium-dislocation behaviour. The low angle boundary, with a misfit angle of ≈1/5 °, was found

  4. Theoretical Analysis of Interferometer Wave Front Tilt and Fringe Radiant Flux on a Rectangular Photodetector

    Directory of Open Access Journals (Sweden)

    Franz Konstantin Fuss

    2013-09-01

    Full Text Available This paper is a theoretical analysis of mirror tilt in a Michelson interferometer and its effect on the radiant flux over the active area of a rectangular photodetector or image sensor pixel. It is relevant to sensor applications using homodyne interferometry where these opto-electronic devices are employed for partial fringe counting. Formulas are derived for radiant flux across the detector for variable location within the fringe pattern and with varying wave front angle. The results indicate that the flux is a damped sine function of the wave front angle, with a decay constant of the ratio of wavelength to detector width. The modulation amplitude of the dynamic fringe pattern reduces to zero at wave front angles that are an integer multiple of this ratio and the results show that the polarity of the radiant flux changes exclusively at these multiples. Varying tilt angle causes radiant flux oscillations under an envelope curve, the frequency of which is dependent on the location of the detector with the fringe pattern. It is also shown that a fringe count of zero can be obtained for specific photodetector locations and wave front angles where the combined effect of fringe contraction and fringe tilt can have equal and opposite effects. Fringe tilt as a result of a wave front angle of 0.05° can introduce a phase measurement difference of 16° between a photodetector/pixel located 20 mm and one located 100 mm from the optical origin.

  5. Evaluation of spontaneous baroreflex response after 28 days head down tilt bedrest

    Science.gov (United States)

    Hughson, R. L.; Yamamoto, Y.; Butler, G. C.; Güell, A.; Gharib, C.

    The spontaneous baroreflex response was evaluated during supine rest and head up tilt (60°) before and immediately after a 28 day 6° HDT bedrest in 6 healthy adult men (age 30-42 years). Sequences of 3 or more beats where RR-interval and systolic blood pressure changed in the same direction were used to evaluate baroreflex response slope (BRS). Prior to bedrest, the mean BRS and RR-interval were 18.0 ± 3.9 ms/mm Hg and 926 ± 61 ms at rest and 10.5 ± 2.5 ms/mm Hg and 772 ± 63 ms during the first 10 min of 60° tilt. Following bedrest, these values changed to 15.6 ± 2.7 ms/mm Hg and 780 ± 53 ms at rest, and to 6.5 ± 1.2 ms/mm Hg and 636 ± 44 ms during tilt. Thus, (1) the spontaneous baroreflex can be evaluated in human subjects during experiments of orthostatic stress; (2) the baroreflex slope was reduced on going from supine to the head up tilt position; and (3) 28 days of bedrest reduced the spontaneous baroreflex slope.

  6. Impaired Cerebral Autoregulation during Head Up Tilt in Patients with Severe Brain Injury.

    Directory of Open Access Journals (Sweden)

    Christian Gunge Riberholt

    Full Text Available Early mobilization is of importance for improving long-term outcome for patients after severe acquired brain injury. A limiting factor for early mobilization by head-up tilt is orthostatic intolerance. The purpose of the present study was to examine cerebral autoregulation in patients with severe acquired brain injury and a low level of consciousness. Fourteen patients with severe acquired brain injury and orthostatic intolerance and fifteen healthy volunteers were enrolled. Blood pressure was evaluated by pulse contour analysis, heart rate and RR-intervals were determined by electrocardiography, middle cerebral artery velocity was evaluated by transcranial Doppler, and near-infrared spectroscopy determined frontal lobe oxygenation in the supine position and during head-up tilt. Cerebral autoregulation was evaluated as the mean flow index calculated as the ratio between middle cerebral artery mean velocity and estimated cerebral perfusion pressure. Patients with acquired brain injury presented an increase in mean flow index during head-up tilt indicating impaired autoregulation (P < 0.001. Spectral analysis of heart rate variability in the frequency domain revealed lower magnitudes of ~0.1 Hz spectral power in patients compared to healthy controls suggesting baroreflex dysfunction. In conclusion, patients with severe acquired brain injury and orthostatic intolerance during head-up tilt have impaired cerebral autoregulation more than one month after brain injury.

  7. Tilted Bianchi type I dust fluid cosmological model in general relativity

    Indian Academy of Sciences (India)

    In this paper, we have investigated a tilted Bianchi type I cosmological model filled with dust of perfect fluid in general relativity. To get a determinate solution, we have assumed a condition = between metric potentials. The physical and geometrical aspects of the model together with singularity in the model are also ...

  8. Initial circulatory responses to changes in posture: influence of the angle and speed of tilt

    NARCIS (Netherlands)

    Sprangers, R. L.; Veerman, D. P.; Karemaker, J. M.; Wieling, W.

    1991-01-01

    To assess if changes in the angle or speed of tilt could account for the differences between the initial (first 30 s) circulatory responses induced by active and passive changes in posture, as found in previous studies, we investigated the initial heart rate and blood pressure responses induced by

  9. An Approximate Cone Beam Reconstruction Algorithm for Gantry-Tilted CT Using Tangential Filtering

    Directory of Open Access Journals (Sweden)

    Ming Yan

    2006-01-01

    Full Text Available FDK algorithm is a well-known 3D (three-dimensional approximate algorithm for CT (computed tomography image reconstruction and is also known to suffer from considerable artifacts when the scanning cone angle is large. Recently, it has been improved by performing the ramp filtering along the tangential direction of the X-ray source helix for dealing with the large cone angle problem. In this paper, we present an FDK-type approximate reconstruction algorithm for gantry-tilted CT imaging. The proposed method improves the image reconstruction by filtering the projection data along a proper direction which is determined by CT parameters and gantry-tilted angle. As a result, the proposed algorithm for gantry-tilted CT reconstruction can provide more scanning flexibilities in clinical CT scanning and is efficient in computation. The performance of the proposed algorithm is evaluated with turbell clock phantom and thorax phantom and compared with FDK algorithm and a popular 2D (two-dimensional approximate algorithm. The results show that the proposed algorithm can achieve better image quality for gantry-tilted CT image reconstruction.

  10. Hemodynamic and symptomatic effects of acute interventions on tilt in patients with postural tachycardia syndrome

    Science.gov (United States)

    Gordon, V. M.; Opfer-Gehrking, T. L.; Novak, V.; Low, P. A.

    2000-01-01

    A variety of approaches have been used to alleviate symptoms in postural tachycardia syndrome (POTS). Drugs reported to be of benefit include midodrine, propranolol, clonidine, and phenobarbital. Other measures used include volume expansion and physical countermaneuvers. These treatments may influence pathophysiologic mechanisms of POTS such as alpha-receptor dysfunction, beta-receptor supersensitivity, venous pooling, and brainstem center dysfunction. The authors prospectively studied hemodynamic indices and symptom scores in patients with POTS who were acutely treated with a variety of interventions. Twenty-one subjects who met the criteria for POTS were studied (20 women, 1 man; mean age, 28.7 +/- 6.8 y; age range, 14-39 y). Patients were studied with a 5-minute head-up tilt protocol, ECG monitoring, and noninvasive beat-to-beat blood pressure monitoring, all before and after the administration of an intervention (intravenous saline, midodrine, propranolol, clonidine, or phenobarbital). The hemodynamic indices studied were heart rate (ECG) and systolic, mean, and diastolic blood pressure. Patients used a balanced verbal scale to record any change in their symptoms between the tilts. Symptom scores improved significantly after the patients received midodrine and saline. Midodrine and propranolol reduced the resting heart rate response to tilt (p midodrine and intravenous saline are effective in decreasing symptoms on tilt in patients with POTS when given acutely. Effects of treatments on heart rate and blood pressure responses generally reflected the known pharmacologic mechanisms of the agents.

  11. Tilt shift determinations with spatial-carrier phase-shift method in temporal phase-shift interferometry

    International Nuclear Information System (INIS)

    Liu, Qian; Wang, Yang; He, Jianguo; Ji, Fang; Wang, Baorui

    2014-01-01

    An algorithm is proposed to deal with tilt-shift errors in temporal phase-shift interferometry (PSI). In the algorithm, the tilt shifts are detected with the spatial-carrier phase-shift (SCPS) method and then the tilt shifts are applied as priori information to the least-squares fittings of phase retrieval. The algorithm combines the best features of the SCPS and the temporal PSI. The algorithm could be applied to interferograms of arbitrary aperture without data extrapolation for the Fourier transform is not involved. Simulations and experiments demonstrate the effectiveness of the algorithm. The statistics of simulation results show a satisfied accuracy in detecting tilt-shift errors. Comparisons of the measurements with and without environmental vibration show that the proposed algorithm could compensate tilt-shift errors and retrieve wavefront phase accurately. The algorithm provides an approach to retrieve wavefront phase for the temporal PSI in vibrating environment. (paper)

  12. Tilted columnar thin film coatings with anisotropic light scattering properties for solar energy applications

    Science.gov (United States)

    Sadeghi-Khosravieh, Saba

    The main goal of this thesis is to show the versatility of glancing angle deposition (GLAD) thin films in applications. This research is first focused on studying the effect of select deposition variables in GLAD thin films and secondly, to demonstrate the flexibility of GLAD films to be incorporated in two different applications: (1) as a reflective coating in low-level concentration photovoltaic systems, and (2) as an anode structure in dye-sensitized solar cells (DSSC). A particular type of microstructure composed of tilted micro-columns of titanium is fabricated by GLAD. The microstructures form elongated and fan-like tilted micro-columns that demonstrate anisotropic scattering. The thin films texture changes from fiber texture to tilted fiber texture by increasing the vapor incidence angle. At very large deposition angles, biaxial texture forms. The morphology of the thin films deposited under extreme shadowing condition and at high temperature (below recrystallization zone) shows a porous and inclined micro-columnar morphology, resulting from the dominance of shadowing over adatom surface diffusion. The anisotropic scattering behavior of the tilted Ti thin film coatings is quantified by bidirectional reflectance distribution function (BRDF) measurements and is found to be consistent with reflectance from the microstructure acting as an array of inclined micro-mirrors that redirect the incident light in a non-specular reflection. A silver-coating of the surface of the tilted-Ti micro-columns is performed to enhance the total reflectance of the Ti-thin films while keeping the anisotropic scattering behavior. By using such coating is as a booster reflector in a laboratory-scale low-level concentration photovoltaic system, the short-circuit current of the reference silicon solar cell by 25%. Finally, based on the scattering properties of the tilted microcolumnar microstructure, its scattering effect is studied as a part of titanium dioxide microstructure for the

  13. Preliminary Opto-Mechanical Design for the X2000 Transceiver

    Science.gov (United States)

    Hemmati, H.; Page, N. A.

    2000-01-01

    Preliminary optical design and mechanical conceptual design for a 30 cm aperture transceiver are described. A common aperture is used for both transmit and receive. Special attention was given to off-axis and scattered light rejection and isolation of the receive channel from the transmit channel. Requirements, details of the design and preliminary performance analysis of the transceiver are provided.

  14. Gravity influences the visual representation of object tilt in parietal cortex.

    Science.gov (United States)

    Rosenberg, Ari; Angelaki, Dora E

    2014-10-22

    Sensory systems encode the environment in egocentric (e.g., eye, head, or body) reference frames, creating inherently unstable representations that shift and rotate as we move. However, it is widely speculated that the brain transforms these signals into an allocentric, gravity-centered representation of the world that is stable and independent of the observer's spatial pose. Where and how this representation may be achieved is currently unknown. Here we demonstrate that a subpopulation of neurons in the macaque caudal intraparietal area (CIP) visually encodes object tilt in nonegocentric coordinates defined relative to the gravitational vector. Neuronal responses to the tilt of a visually presented planar surface were measured with the monkey in different spatial orientations (upright and rolled left/right ear down) and then compared. This revealed a continuum of representations in which planar tilt was encoded in a gravity-centered reference frame in approximately one-tenth of the comparisons, intermediate reference frames ranging between gravity-centered and egocentric in approximately two-tenths of the comparisons, and in an egocentric reference frame in less than half of the comparisons. Altogether, almost half of the comparisons revealed a shift in the preferred tilt and/or a gain change consistent with encoding object orientation in nonegocentric coordinates. Through neural network modeling, we further show that a purely gravity-centered representation of object tilt can be achieved directly from the population activity of CIP-like units. These results suggest that area CIP may play a key role in creating a stable, allocentric representation of the environment defined relative to an "earth-vertical" direction. Copyright © 2014 the authors 0270-6474/14/3414170-11$15.00/0.

  15. Determination of the Basic Friction Angle of Rock Surfaces by Tilt Tests

    Science.gov (United States)

    Jang, Hyun-Sic; Zhang, Qing-Zhao; Kang, Seong-Seung; Jang, Bo-An

    2018-04-01

    Samples of Hwangdeung granite from Korea and Berea sandstone from USA, both containing sliding planes, were prepared by saw-cutting or polishing using either #100 or #600 grinding powders. Their basic friction angles were measured by direct shear testing, triaxial compression testing, and tilt testing. The direct shear tests and triaxial compression tests on the saw-cut, #100, and #600 surfaces indicated that the most reliable results were obtained from the #100 surface: basic friction angle of 29.4° for granite and 34.1° for sandstone. To examine the effect of surface conditions on the friction angle in tilt tests, the sliding angles were measured 50 times with two surface conditions (surfaces cleaned and not cleaned after each measurement). The initial sliding angles were high regardless of rock type and surface conditions and decreased exponentially as measurements continued. The characteristics of the sliding angles, differences between tilt tests, and dispersion between measurements in each test indicated that #100 surface produced the most reliable basic friction angle measurement. Without cleaning the surfaces, the average angles for granite (32 measurements) and sandstone (23 measurements) were similar to the basic friction angle. When 20-50 measurements without cleaning were averaged, the basic friction angle was within ± 2° for granite and ± 3° for sandstone. Sliding angles using five different tilting speeds were measured but the average was similar, indicating that tilting speed (between 0.2° and 1.6°/s) has little effect on the sliding angle. Sliding angles using four different sample sizes were measured with the best results obtained for samples larger than 8 × 8 cm.

  16. Renormalization of Coulomb interactions in a system of two-dimensional tilted Dirac fermions

    Science.gov (United States)

    Lee, Yu-Wen; Lee, Yu-Li

    2018-01-01

    We investigate the effects of long-ranged Coulomb interactions in a tilted Dirac semimetal in two dimensions by using the perturbative renormalization-group (RG) method. Depending on the magnitude of the tilting parameter, the undoped system can have either Fermi points (type I) or Fermi lines (type II). Previous studies usually performed the renormalization-group transformations by integrating out the modes with large momenta. This is problematic when the Fermi surface is open, like type-II Dirac fermions. In this work we study the effects of Coulomb interactions, following the spirit of Shankar [Rev. Mod. Phys. 66, 129 (1994), 10.1103/RevModPhys.66.129], by introducing a cutoff in the energy scale around the Fermi surface and integrating out the high-energy modes. For type-I Dirac fermions, our result is consistent with that of the previous work. On the other hand, we find that for type-II Dirac fermions, the magnitude of the tilting parameter increases monotonically with lowering energies. This implies the stability of type-II Dirac fermions in the presence of Coulomb interactions, in contrast with previous results. Furthermore, for type-II Dirac fermions, the velocities in different directions acquire different renormalization even if they have the same bare values. By taking into account the renormalization of the tilting parameter and the velocities due to the Coulomb interactions, we show that while the presence of a charged impurity leads only to charge redistribution around the impurity for type-I Dirac fermions, for type-II Dirac fermions, the impurity charge is completely screened, albeit with a very long screening length. The latter indicates that the temperature dependence of physical observables are essentially determined by the RG equations we derived. We illustrate this by calculating the temperature dependence of the compressibility and specific heat of the interacting tilted Dirac fermions.

  17. Jahn-Teller distortions, cation ordering and octahedral tilting in perovskites

    International Nuclear Information System (INIS)

    Lufaso, M.W.; Woodward, P.M.

    2004-01-01

    In transition metal oxides, preferential occupation of specific d orbitals on the transition metal ion can lead to the development of a long-range ordered pattern of occupied orbitals. This phenomenon, referred to as orbital ordering, is usually observed indirectly from the cooperative Jahn-Teller distortions (CJTDs) that result as a consequence of the orbital ordering. This paper examines the interplay between orbital ordering, octahedral tilting and cation ordering in perovskites. Both ternary AMX 3 perovskites containing an active Jahn-Teller (J-T) ion on the octahedral site and quaternary A 2 MM'X 6 perovskites containing a J-T ion on one-half of the octahedral sites have been examined. In AMX 3 perovskites, the tendency is for the occupied 3d 3x 2 -r 2 and 3d 3z 2 -r 2 orbitals to order in the ac plane, as exemplified by the crystal structures of LaMnO 3 and KCuF 3 . This arrangement maintains a favorable coordination environment for the anion sites. In AMX 3 perovskites, octahedral tilting tends to enhance the magnitude of the J-T distortions. In A 2 MM'X 6 perovskites, the tendency is for the occupied 3d 3z 2 -r 2 orbitals to align parallel to the c axis. This pattern maintains a favorable coordination environment about the symmetric M'-cation site. The orbital ordering found in rock-salt ordered A 2 MM'X 6 perovskites is compatible with octahedral rotations about the c axis (Glazer tilt system a 0 a 0 c - ) but appears to be incompatible with GdFeO 3 -type octahedral tilting (tilt system - b + a - ). (orig.)

  18. Optimization and limit of a tilt manipulation stage based on the electrowetting-on-dielectric principle

    Science.gov (United States)

    Tan, Xiao; Tao, Zhi; Suzuki, Kenji; Li, Haiwang

    2017-12-01

    This work designed a new tilt manipulation stage based on the electrowetting-on-dielectric (EWOD) principle as the actuating mechanism and investigated the performance of that stage. The stage was fabricated using a universal MEMS (Micro-Electro-Mechanical System) fabrication method. In the previously demonstrated form of this device, the tilt stage consisted of a top plate that functions as a mirror, a bottom plate that was designed for changing the shape of water droplets, and supporters that were fixed between the top and bottom plate. That device was actuated by a voltage applied to the bottom plate, resulting in a static electric force actuating the shape change in the droplets by moving the top plate in the vertical direction. Previous experimental results indicated that that device can tilt at up to ±1.8°, with a resolution of 7 μm in displacement and 0.05° in angle. By selecting the best combination of the dielectric layer, the tilt angle was maximized. The new device, fabricated using a common and straightforward fabrication method, avoids deflection of the top plate and grounding in the bottom plate. Because of the limit of Teflon and other MEMS materials, this device has a tilt angle in the range of 3.2-3.5° according to the experimental data for friction and the EWOD device limit, which is close to 1.8°. This paper also describe the investigation of the effects of various parameters, e.g., various dielectric materials, thicknesses, and droplet type and volume, on the performance of the stage. The results indicate that the apparent frictions coefficient of the solid-liquid interface may remain constant, i.e., the friction force is proportional to the normal support force and the apparent frictions coefficient.

  19. Respostas autonômicas cardíacas à manobra de tilt em adolescentes obesos Cardiac autonomic responses to head-up tilt in obese adolescents

    Directory of Open Access Journals (Sweden)

    Antônio Fernando Brunetto

    2005-10-01

    Full Text Available INTRODUÇÃO: A obesidade está associada às alterações do sistema nervoso autônomo. Estudos prévios em adultos têm mostrado que obesos apresentam resposta autonômica cardíaca diminuída frente a mudanças posturais. Contudo, pouco se sabe sobre o impacto do sobrepeso na adolescência quanto às respostas autonômicas ao estresse postural passivo. OBJETIVO: Comparar as respostas autonômicas cardíacas à manobra de tilt entre adolescentes obesos e não-obesos mediante análise da variabilidade da freqüência cardíaca (VFC. MÉTODOS: Quatorze adolescentes obesos (15,5±1,6 anos foram comparados com 20 adolescentes não-obesos (15,4±0,8 anos. A modulação autonômica cardíaca foi estudada mediante análise da variabilidade da freqüência cardíaca de trechos de cinco minutos de registro de intervalos RR antes e depois da inclinação da mesa de tilt a 70º. A VFC foi estudada no domínio do tempo (DT e no domínio da freqüência (DF. Os componentes espectrais foram estudados na baixa (LF e na alta freqüência (HF e pela razão LF/HF. RESULTADOS: Adolescentes obesos demonstraram menor HF em unidades normalizadas (38,2±11.1 vs 53,9±15,5, pINTRODUCTION: Obesity is associated with alterations of the autonomic nervous system. Previous studies in adults have shown that obese individuals present a decreased cardiac autonomic response to postural challenges. However, little is known about the impact of overweight on autonomic responses to passive postural stress in adolescents. OBJECTIVE: to compare cardiac autonomic responses to the head-up tilt maneuver between obese and non-obese adolescents by analyzing heart rate variability. METHODS: Fourteen obese adolescents (15.5±1.6 years were compared with twenty non-obese subjects (15.4±0.8 years. Cardiac autonomic modulation was studied by heart rate variability (HRV analysis of 5 minute RR interval recordings before and after a 70º head-up tilt maneuver. HRV was analyzed according to

  20. L'Abbe Henri Breuil: Archaeologist

    Directory of Open Access Journals (Sweden)

    Lawrence Guy Straus

    1992-05-01

    Full Text Available In his otherwise excellent book, A History of Archaeological Thought, Trigger (1989: 156 makes only one passing reference in a half-sentence to the central figure in the development of Paleolithic prehistory in the first half of the 20th century -- and manages to get his name wrong, confusing Henri Breuil with his long-time, close colleague, Hugo Obenrnaie . Thirty years after his death, Breuil's role in the history of Old World prehistory required more serious consideration. He was a seminal figure not only in rock art studies, but also in the archaeology of at least France, Spain, England, Portugal, South Africa, and China. Before I had read Trigger's work or Sackett's (1991 critique of my supposed misinterpretation of Breuil's theoretical stance (e.g., Straus 1986, 1987, I had presented a review of Breuil's contributions in the 1991 Annual Snead-Wertheim Lecture in Anthropology and History at the University of New Mexico (Straus n.d.. The following is a brief summary of some of my conclusions.

  1. A new measurement for posterior tilt predicts reoperation in undisplaced femoral neck fractures: 113 consecutive patients treated by internal fixation and followed for 1 year

    DEFF Research Database (Denmark)

    Palm, Henrik; Gosvig, Kasper; Krasheninnikoff, Michael

    2009-01-01

    posterior tilt was an accurate predictor of failure (p = 0.002). 14/25 of posteriorly tilted fractures > or = 20 degrees were reoperated, as compared to 12/88 of fractures with less tilt (p analysis including sex, age, ASA score, cognitive function, new mobility...

  2. Perancangan dan Implementasi Sistem Remote Tilting Antenna untuk Aplikasi Base Station

    Directory of Open Access Journals (Sweden)

    ARSYAD RAMADHAN DARLIS

    2017-06-01

    Full Text Available Abstrak Pada kondisi pembangunan suatu jaringan seluler baru, permasalahan coverage area terkadang perlu penanganan khusus. Jika coverage area dari suatu base station terlalu besar maka dapat mengakibatkan saling tumpang tindih (overlap dengan sel yang berdekatan. Hal ini akan meningkatkan interferensi daya antar sel, yang kemudian berakibat pada penurunan kualitas layanan. Salah satu bentuk solusi untuk dapat memenuhi persyaratan coverage area, kinerja jaringan seluler, dan juga memenuhi tingkat keselamatan engineer adalah dengan menggunakan metoda down tilting antenna melalui wireless. Penetapan metoda down tilting antenna dilakukan dengan membuat suatu peralatan yang dapat menggerakkan posisi antenna pada base station. Perangkat yang diimplementasikan terdiri atas Transmitter, Receiver, Motor DC, Driver Motor, Logam Pengait, dan Antena. Sinyal yang berfungsi sebagai pengendali masuk ke Transmitter dan selanjutnya diolah oleh Receiver. Sinyal keluaran dari Receiver digunakan untuk mengendalikan motor DC melalui driver motor yang mengendalikan pergerakan dari Antenna Base Station. Pada penelitian ini, sistem telah dapat diuji memalui pergerakan antenna sampai dengan jarak 10 m. Tingkat kemiringan antena dibandingkan dengan pergeseran logam berkait menunjukan hasil yang linear. Setiap pergeseran 0,5 cm akan menyebabkan perubahan kemiringan antenna sebesar 1 derajat.   Kata kunci: Remote Tilting, Motor DC, Transmitter, Receiver, Base Station Abstract On the state of development of a new mobile network, problem coverage area sometimes need special handling. If the coverage area of a Base Station is too big then it may lead to overlap ( overlap with adjacent cells. This will improve inter- cell interference power, which then resulted in a decrease in the quality of service. One form of solutions to meet the requirements of the coverage area, the performance of cellular networks, and also meet the level of safety engineers is to use the method of

  3. The Effect of Pelvic Tilt and Femoral Head Size on Hip Range-of-Motion to Impingement.

    Science.gov (United States)

    McCarthy, Thomas F; Nevelos, Jim; Elmallah, Randa K; Chughtai, Morad; Khlopas, Anton; Alipit, Vincent; Wagner, Timothy C; Mont, Michael A

    2017-11-01

    About 50%-70% of dislocators have cups placed within so-called "safe zones." It has been postulated that factors such as femoral head size and pelvic tilt, obliquity, or rotation may influence postoperative stability. Therefore, we assessed varying degrees of pelvic tilt and head sizes on the range of motion (ROM) to impingement. A hip simulator was used to import models of 10 subjects who performed object pickup, squatting, and low-chair rising. Parameters were set for pelvic tilt, stem version, and the specific motions as defined by the subjects. Femur-to-pelvis relative motions were determined for abduction/adduction, internal/external rotation, and flexion/extension. Varying tilt angles were tested. Thirty-two millimeter and 36-mm head with a standard cup and 42-mm dual mobility cup were tested. Cup orientations for abduction and anteversion combinations were chosen, and computations of minimum clearances or impingement between components were made. The ROM to impingement varied with the different pelvic tilts and femoral head sizes and with the different motions. The larger the head size, the larger the impingement-free ROM. Negative 10° of pelvic tilt led to the largest impingement-free zone, whereas 10° of forward tilt was associated with fewer impingement-free cup anteversion and abduction angle combinations. Variations in pelvic tilt had the greatest influence on object pickup and affected the impingement-free "safe zone." Targets for impingement-free motion may be smaller when considering varying pelvic tilts and femoral head sizes, particularly for certain activities, such as object pickup. These findings may indicate the need for more individualized patient planning. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Establishing a diffuse solar radiation model for determining the optimum tilt angle of solar surfaces in Tabass, Iran

    International Nuclear Information System (INIS)

    Khorasanizadeh, H.; Mohammadi, K.; Mostafaeipour, A.

    2014-01-01

    Highlights: • Optimum tilt angles of solar surfaces in the Iranian city of Tabass are determined. • Due to lack of measured diffuse data, a new two variables diffuse model is established. • The monthly optimum tilt varies between 0° and 64° and the best annual tilt is 32°. • The semi-yearly tilt strategy of 10° for warm and 55° for cold periods are suggested. • Radiation components obtained for horizontal, tilted and vertical surfaces are compared. - Abstract: In this study the optimum tilt angle for south-facing solar surfaces in Tabass, Iran, for the fixed monthly, seasonal, semi-yearly and yearly adjustments were calculated. Due to lack of measured diffuse solar radiation data, to predict the horizontal diffuse radiation nine diffuse models from three different categories were established. Based on some statistical indicators the three degree model, in which both clearness index and relative sunshine duration are variables, was recognized the best. The monthly optimum tilt varies from 0° in June and July up to 64° in December and the yearly optimum tilt is around 32°, which is very close to latitude of Tabass (33.36°). For different adjustments, particularly for a vertically mounted surface, the received monthly mean daily solar radiation components and the annual solar energy gains were calculated and compared. Total yearly extra solar gain for the monthly, seasonal, semi-yearly and yearly optimally adjusted surfaces compared to that of horizontal surface are 23.15%, 21.55%, 21.23% and 13.76%, respectively. The semi-yearly tilt adjustment of 10° for warm period (April–September) and 55° for cold period (October–March) is highly recommended, since it provides almost the same level of annual solar energy gain as those of monthly and seasonal adjustments

  5. A new method to detect and correct sample tilt in scanning transmission electron microscopy bright-field imaging

    Energy Technology Data Exchange (ETDEWEB)

    Brown, H.G. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Ishikawa, R.; Sánchez-Santolino, G. [Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan); Lugg, N.R., E-mail: shibata@sigma.t.u-tokyo.ac.jp [Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan); Ikuhara, Y. [Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan); Allen, L.J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Shibata, N. [Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan)

    2017-02-15

    Important properties of functional materials, such as ferroelectric shifts and octahedral distortions, are associated with displacements of the positions of lighter atoms in the unit cell. Annular bright-field scanning transmission electron microscopy is a good experimental method for investigating such phenomena due to its ability to image light and heavy atoms simultaneously. To map atomic positions at the required accuracy precise angular alignment of the sample with the microscope optical axis is necessary, since misalignment (tilt) of the specimen contributes to errors in position measurements of lighter elements in annular bright-field imaging. In this paper it is shown that it is possible to detect tilt with the aid of images recorded using a central bright-field detector placed within the inner radius of the annular bright-field detector. For a probe focus near the middle of the specimen the central bright-field image becomes especially sensitive to tilt and we demonstrate experimentally that misalignment can be detected with a precision of less than a milliradian, as we also confirm in simulation. Coma in the probe, an aberration that can be misidentified as tilt of the specimen, is also investigated and it is shown how the effects of coma and tilt can be differentiated. The effects of tilt may be offset to a large extent by shifting the diffraction plane detector an amount equivalent to the specimen tilt and we provide an experimental proof of principle of this using a segmented detector system. - Highlights: • Octahedral distortions are associated with displacements of lighter atoms. • Annular bright-field imaging is sensitive to light and heavy atoms simultaneously. • Mistilt of the specimen leads to errors in position measurements of lighter elements. • It is possible to detect tilt using images taken by a central bright-field detector. • Tilt may be offset by shifting the diffraction plane detector by an equivalent amount.

  6. Tilt teste no diagnóstico diferencial da "epilepsia" resistente ao tratamento Tilt table test in the differential diagnosis of refractory "epilepsy"

    Directory of Open Access Journals (Sweden)

    Renata Rodrigues Teixeira de Castro

    2006-11-01

    Full Text Available A epilepsia é uma das causas mais freqüentes de distúrbios neurológicos em adultos jovens. Relatamos um caso em que uma paciente conviveu durante doze anos com o diagnóstico de epilepsia resistente ao tratamento, quando, na verdade, a causa de seus sintomas pôde ser encontrada com a realização do teste de inclinação (tilt teste. O cardiologista deve estar alerta para o possível diagnóstico de síncope neurocardiogênica em pacientes previamente diagnosticados como portadores de epilepsia, especialmente naqueles com difícil controle terapêutico.Epilepsy is one of the most frequent causes of neurological disorders in young adults. We report the case of a patient who lived with the diagnosis of refractory epilepsy for twelve years, when actually the cause of the symptoms could be found with the performance of a tilt table test. Cardiologists should be aware of the possible diagnosis of neurocardiogenic syncope in patients previously diagnosed with epilepsy, especially in those with difficult therapeutic control.

  7. Pixel-size-maintained image reconstruction of digital holograms on arbitrarily tilted planes by the angular spectrum method.

    Science.gov (United States)

    Jeong, Seung Jun; Hong, Chung Ki

    2008-06-01

    We present an effective method for the pixel-size-maintained reconstruction of images on arbitrarily tilted planes in digital holography. The method is based on the plane wave expansion of the diffraction wave fields and the three-axis rotation of the wave vectors. The images on the tilted planes are reconstructed without loss of the frequency contents of the hologram and have the same pixel sizes. Our method shows good results in the extreme cases of large tilting angles and in the region closer than the paraxial case. The effectiveness of the method is demonstrated by both simulation and experiment.

  8. Numerical Study of Impingement Location of Liquid Jet Poured from a Tilting Ladle with Lip Spout

    Science.gov (United States)

    Castilla, R.; Gamez-Montero, P. J.; Raush, G.; Khamashta, M.; Codina, E.

    2017-04-01

    A new approach for simulating liquid poured from a tilting lip spout is presented, using neither a dynamic mesh nor the moving solid solution method. In this case only the tilting ladle is moving, so we propose to rotate the gravitational acceleration at an angular velocity prescribed by a geometrical and dynamical calculation to keep the poured flow rate constant. This angular velocity is applied to modify the orientation of the gravity vector in computational fluid dynamics (CFD) simulations using the OpenFOAM® toolbox. Also, fictitious forces are considered. The modified solver is used to calculate the impingement location for six spout geometries and compare the jet dispersion there. This method could offer an inexpensive tool to calculate optimal spout geometries to reduce sprue size in the metal casting industry.

  9. Influence of body laterality on recovery from subjective visual vertical tilt after vestibular neuritis.

    Science.gov (United States)

    Toupet, Michel; Van Nechel, Christian; Bozorg Grayeli, Alexis

    2014-01-01

    The subjective visual vertical (SVV) is an indicator of vestibular otolithic function and mainly processed by the nondominant parietal cortex. We investigated the hypothesis that recovery from SVV tilt after vestibular neuritis can be influenced by the body's lateral preference. This prospective cohort follow-up study included 254 consecutive adult patients with vestibular neuritis. The recovery from SVV tilt was faster in patients with a left hand or eye dominance than in those with a right dominance. While in left-handers the side of the neuritis did not affect the speed of recovery, in right-handed subjects, the recovery from a right-sided neuritis was significantly slower than from a left-sided affection. These observations suggest that subjects with a left sensorimotor dominance have developed more significant midline-crossing projections to the parietal cortex, allowing them to cope faster with a unilateral vestibular deficit.

  10. Barrier versus tilt exchange gate operations in spin-based quantum computing

    Science.gov (United States)

    Shim, Yun-Pil; Tahan, Charles

    2018-04-01

    We present a theory for understanding the exchange interaction between electron spins in neighboring quantum dots, either by changing the detuning of the two quantum dots or independently tuning the tunneling barrier between quantum dots. The Hubbard model and a more realistic confining-potential model are used to investigate how the tilting and barrier control affect the effective exchange coupling and thus the gate fidelity in both the detuning and symmetric regimes. We show that the exchange coupling is less sensitive to the charge noise through tunnel barrier control (while allowing for exchange coupling operations on a sweet spot where the exchange interaction has zero derivative with respect to the detuning). Both GaAs and Si quantum dots are considered, and we compare our results with experimental data showing qualitative agreements. Our results answer the open question of why barrier gates are preferable to tilt gates for exchange-based gate operations.

  11. Surface tension-induced PDMS micro-pillars with controllable tips and tilt angles

    KAUST Repository

    Li, Huawei

    2013-12-21

    This paper reports a novel method to fabricate three-dimensional (3D) polydimethylsiloxane (PDMS) micro-pillars using a CO2 laser-machined poly(methyl methacrylate) (PMMA) mold with through-holes. This method eliminates the requirements of expensive and complicated facilities to fabricate a 3D mold. The micro-pillars were formed by the capillary force that draws PDMS into the through-holes of the PMMA mold. The tilt angles of the micro-pillars depend on the tilt angles of the through-holes in the mold, and the concave and convex micro-lens tip shapes of the PDMS micro-pillars can be modified by changing the surface wettability of the PMMA through-holes.

  12. Tilt dynamics of an electrostatically actuated microoscillator at a liquid-liquid interface

    International Nuclear Information System (INIS)

    Allievi, Alejandro

    2011-01-01

    We investigate the time-domain tilt response of an electrostatically actuated mechanical microoscillator positioned at a liquid-liquid interface. An analytical model is presented to simulate the microoscillator's rotational motion inside a microchannel completely filled with two immiscible liquids. The model considers two coupled ordinary differential equations; one simulates the mechanical response of the microplate-microbeam assembly making-up the mi-crooscillator and the other provides the behaviour of the electrical charge responsible for the electrostatic moment that tilts the microplate. Results show that remarkable improvements in sampling time and sensitivity can be obtained using a bi-liquid configuration versus its single-liquid counterpart. Therefore, enhanced performance of mechanical microsensors for liquids could be achieved.

  13. Transverse Seebeck and Peltier effect in tilted metal-semiconductor multilayer structures

    International Nuclear Information System (INIS)

    Reitmaier, Christina

    2012-01-01

    Whether in aerospace, automobile industry or in home appliances, thermoelectric effects find use in many areas of technology. This work deals with the investigation of a special form of these effects, the transversal Seebeck- and Peltier effect. Via modelling under variation of the sample parameters the cooling efficiencies, the attainable temperature differences and the Figures of merit are optimised and than suitable samples are produced according to these specifications. With these tilted metal semiconductor multilayer structures consisting of lead and bismuth telluride a transversal Peltier effect is observed. Moreover, the generation of electric power is examined via the transversal Seebeck effect. In tilted Pb-Bi2Te3 multilayers the efficiency is measured with the conversion by heat in electric power and is compared to model calculations. (orig.)

  14. A note on tilted Bianchi type VIh models: the type III bifurcation

    Science.gov (United States)

    Coley, A. A.; Hervik, S.

    2008-10-01

    In this note we complete the analysis of Hervik, van den Hoogen, Lim and Coley (2007 Class. Quantum Grav. 24 3859) of the late-time behaviour of tilted perfect fluid Bianchi type III models. We consider models with dust, and perfect fluids stiffer than dust, and eludicate the late-time behaviour by studying the centre manifold which dominates the behaviour of the model at late times. In the dust case, this centre manifold is three-dimensional and can be considered a double bifurcation as the two parameters (h and γ) of the type VIh model are varied. We therefore complete the analysis of the late-time behaviour of tilted ever-expanding Bianchi models of types I VIII.

  15. Motorcycle That See: Multifocal Stereo Vision Sensor for Advanced Safety Systems in Tilting Vehicles

    Directory of Open Access Journals (Sweden)

    Gustavo Gil

    2018-01-01

    Full Text Available Advanced driver assistance systems, ADAS, have shown the possibility to anticipate crash accidents and effectively assist road users in critical traffic situations. This is not the case for motorcyclists, in fact ADAS for motorcycles are still barely developed. Our aim was to study a camera-based sensor for the application of preventive safety in tilting vehicles. We identified two road conflict situations for which automotive remote sensors installed in a tilting vehicle are likely to fail in the identification of critical obstacles. Accordingly, we set two experiments conducted in real traffic conditions to test our stereo vision sensor. Our promising results support the application of this type of sensors for advanced motorcycle safety applications.

  16. Motorcycles that See: Multifocal Stereo Vision Sensor for Advanced Safety Systems in Tilting Vehicles

    Science.gov (United States)

    2018-01-01

    Advanced driver assistance systems, ADAS, have shown the possibility to anticipate crash accidents and effectively assist road users in critical traffic situations. This is not the case for motorcyclists, in fact ADAS for motorcycles are still barely developed. Our aim was to study a camera-based sensor for the application of preventive safety in tilting vehicles. We identified two road conflict situations for which automotive remote sensors installed in a tilting vehicle are likely to fail in the identification of critical obstacles. Accordingly, we set two experiments conducted in real traffic conditions to test our stereo vision sensor. Our promising results support the application of this type of sensors for advanced motorcycle safety applications. PMID:29351267

  17. Motorcycle That See: Multifocal Stereo Vision Sensor for Advanced Safety Systems in Tilting Vehicles.

    Science.gov (United States)

    Gil, Gustavo; Savino, Giovanni; Piantini, Simone; Pierini, Marco

    2018-01-19

    Advanced driver assistance systems, ADAS, have shown the possibility to anticipate crash accidents and effectively assist road users in critical traffic situations. This is not the case for motorcyclists, in fact ADAS for motorcycles are still barely developed. Our aim was to study a camera-based sensor for the application of preventive safety in tilting vehicles. We identified two road conflict situations for which automotive remote sensors installed in a tilting vehicle are likely to fail in the identification of critical obstacles. Accordingly, we set two experiments conducted in real traffic conditions to test our stereo vision sensor. Our promising results support the application of this type of sensors for advanced motorcycle safety applications.

  18. Fault diagnosis for tilting-pad journal bearing based on SVD and LMD

    Directory of Open Access Journals (Sweden)

    Zhang Xiaotao

    2016-01-01

    Full Text Available Aiming at fault diagnosis for tilting-pad journal bearing with fluid support developed recently, a new method based on singular value decomposition (SVD and local mean decomposition (LMD is proposed. First, the phase space reconstruction of Hankel matrix and SVD method are used as pre-filter process unit to reduce the random noises in the original signal. Then the purified signal is decomposed by LMD into a series of production functions (PFs. Based on PFs, time frequency map and marginal spectrum can be obtained for fault diagnosis. Finally, this method is applied to numerical simulation and practical experiment data. The results show that the proposed method can effectively detect fault features of tilting-pad journal bearing.

  19. Design Optimization of Tilting-Pad Journal Bearing Using a Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Hamit Saruhan

    2004-01-01

    Full Text Available This article focuses on the use of genetic algorithms in developing an efficient optimum design method for tilting pad bearings. The approach optimizes based on minimum film thickness, power loss, maximum film temperature, and a global objective. Results for a five tilting-pad preloaded bearing are presented to provide a comparison with more traditional optimum design methods such as the gradient-based global criterion method, and also to provide insight into the potential of genetic algorithms in the design of rotor bearings. Genetic algorithms are efficient search techniques based on the idea of natural selection and genetics. These robust methods have gained recognition as general problem solving techniques in many applications.

  20. Tilting at wave beams: a new perspective on the St Andrew's Cross

    Science.gov (United States)

    Akylas, T. R.; Kataoka, T.; Ghaemsaidi, S. J.; Holzenberger, N.; Peacock, T.

    2017-11-01

    The generation of internal gravity waves by a vertically oscillating cylinder that is tilted to the horizontal in a stratified fluid of constant buoyancy frequency, is investigated theoretically and experimentally. This forcing arrangement leads to a variant of the classical St Andrew's Cross that has certain unique features: (i) radiation of wave beams is limited due to a lower cut-off frequency set by the cylinder tilt angle to the horizontal; (ii) the response is essentially three-dimensional, as end effects eventually come into play when the cut-off frequency is approached, however long a cylinder might be. These results follow from kinematic considerations and are also confirmed by laboratory experiments. The kinematic analysis, moreover, suggests a resonance phenomenon near the cut-off frequency, where viscous and nonlinear effects are likely to play an important part. This scenario is examined by an asymptotic model as well as experimentally. Supported in part by NSF Grant DMS-1512925.

  1. De novo formation of left-right asymmetry by posterior tilt of nodal cilia.

    Directory of Open Access Journals (Sweden)

    Shigenori Nonaka

    2005-08-01

    Full Text Available In the developing mouse embryo, leftward fluid flow on the ventral side of the node determines left-right (L-R asymmetry. However, the mechanism by which the rotational movement of node cilia can generate a unidirectional flow remains hypothetical. Here we have addressed this question by motion and morphological analyses of the node cilia and by fluid dynamic model experiments. We found that the cilia stand, not perpendicular to the node surface, but tilted posteriorly. We further confirmed that such posterior tilt can produce leftward flow in model experiments. These results strongly suggest that L-R asymmetry is not the descendant of pre-existing L-R asymmetry within each cell but is generated de novo by combining three sources of spatial information: antero-posterior and dorso-ventral axes, and the chirality of ciliary movement.

  2. 19 years of tilt data on Mt. Vesuvius: state of the art and future perspectives

    Directory of Open Access Journals (Sweden)

    Ciro Ricco

    2013-11-01

    Full Text Available Mt. Vesuvius, located along the SW border of the Campania Plane graben, is one of the most studied volcanoes worldwide, from both the volcanological and the geophysical, geochemical and geodetic point of view. In order to better understand its dynamics, the deformation of the volcano has been already studied since the early ’70s by setting up levelling lines and, since a few years later, through trilateration networks, whereas ground tilt monitoring started in 1993. Tilt variations were recorded by an automatic surface station set up at the Osservatorio Vesuviano (O.V. bunker (OVO and data recorded were transmitted to the O.V. Surveillance Centre in Naples. Afterwards, in 1996 two more identical stations were set up close to Torre del Greco (CMD, and close to Trecase (TRC. In 2002 the data acquisition system was replaced, while at the end of 2011 a Lily borehole sensor was set up at 26 m depth, replacing the old TRC tilt station. The paper describes in details the tilt network of Mt. Vesuvius, its development over time and the data processing procedure; moreover, the ground deformation pattern is discussed, as inferred from the study of 19 years of data and its change during the seismic crises of 1995-1996 and 1999-2000. From the information obtained from the tiltmetric monitoring, a complex deformation pattern can be deduced, strongly dependent on the position of the sites in which the sensors were set up with respect to the morphology of the volcanic edifice and its structural outlines. If we consider the signals as they were recorded, although previously corrected for the influences of the thermo-elastic strain on the sensors, the tilting occurs mainly in the SW direction with rates of about 11 µradians/year on both the western and eastern flanks and of about 13 µradians/year on the southern one. Because tilt vectors point in the long term outward from the summit and towards the subsiding area, this supports the hypothesis of a southern

  3. Study of matrix crack-tilted fiber bundle interaction using caustics and finite element method.

    Science.gov (United States)

    Hao, Wenfeng; Zhu, Jianguo; Zhu, Qi; Yuan, Yanan

    2016-02-01

    In this work, the interaction between the matrix crack and a tilted fiber bundle was investigated via caustics and the finite element method (FEM). First, the caustic patterns at the crack tip with different distances from the tilted fiber were obtained and the stress intensity factors were extracted from the geometry of the caustic patterns. Subsequently, the shielding effect of the fiber bundle in front of the crack tip was analyzed. Furthermore, the interaction between the matrix crack and the broken fiber bundle was discussed. Finally, a finite element simulation was carried out using ABAQUS to verify the experimental results. The results demonstrate that the stress intensity factors extracted from caustic experiments are in excellent agreement with the data calculated by FEM.

  4. Dynamics of thin-skinned fold and thrust belts with a tilted detachment

    Science.gov (United States)

    Fernandez, Naiara; Kaus, Boris J. P.; Epard, Jean-Luc

    2014-05-01

    The formation of the Jura fold and thrust belt is linked to the Alpine orogeny. However, it is still a matter of debate why the Jura was formed tens of kilometres far away from the active deformation front while the Molasse basin that lies in between remained mostly undeformed. Progressive thickening of the Molasse basin due to its infill with sediments, and the existence of a tilted potential detachment level at the Triassic evaporitic units, have been pushed forward as the main causes for the detachment of the Molasse basin and the consequent jump of the deformation front from the Alpine front to the position of the Jura at around 22 Ma or later (e.g Willett and Schlunegger, 2010). In order to better understand the dynamics of a thin-skinned fold and thrust belt with a tilted detachment we have performed systematic forward numerical simulations with the 2D thermo-mechanical finite element code MILAMIN_VEP. The modelled setup consists of a tilted detachment, overlain by a sedimentary cover of constant thickness and a wedge shaped basin infill that makes the initial surface slope of the system to be zero. In this study we have tested the importance of the following factors in the dynamics of such a fold and thrust belt evolution: 1) the applied boundary conditions 2) the angle of a uniformly tilted detachment 3) the end displacement of a curved detachment with a flexural foreland basin profile. The implications of the studied factors are discussed for the case of the Jura-Molasse system. Acknowledgements Funding was provided by the European Research Council under the European Community's Seventh Framework program (FP7/2007-2013) ERC Grant agreement #258830. References Willett, S.D. and Schlunegger, F. 2010, The last phase of deposition in the Swiss Molasse Basin: from foredeep to negative-alpha basin. Basin Research 22, 623-639, doi: 10.1111/j.1365-2117.2009.00435.x

  5. Abrupt Upper-Plate Tilting Upon Slab-Transition-Zone Collision

    Science.gov (United States)

    Crameri, F.; Lithgow-Bertelloni, C. R.

    2017-12-01

    During its sinking, the remnant of a surface plate crosses and interacts with multiple boundaries in Earth's interior. The most-prominent dynamic interaction arises at the upper-mantle transition zone where the sinking plate is strongly affected by the higher-viscosity lower mantle. Within our numerical model, we unravel, for the first time, that this very collision of the sinking slab with the transition zone induces a sudden, dramatic downward tilt of the upper plate towards the subduction trench. The slab-transition zone collision sets parts of the higher-viscosity lower mantle in motion. Naturally, this then induces an overall larger return flow cell that, at its onset, tilts the upper plate abruptly by around 0.05 degrees and over around 10 Millions of years. Such a significant and abrupt variation in surface topography should be clearly visible in temporal geologic records of large-scale surface elevation and might explain continental-wide tilting as observed in Australia since the Eocene or North America during the Phanerozoic. Unravelling this crucial mantle-lithosphere interaction was possible thanks to state-of-the-art numerical modelling (powered by StagYY; Tackley 2008, PEPI) and post-processing (powered by StagLab; www.fabiocrameri.ch/software). The new model that is introduced here to study the dynamically self-consistent temporal evolution of subduction features accurate subduction-zone topography, robust single-sided plate sinking, stronger plates close to laboratory values, an upper-mantle phase transition and, crucially, simple continents at a free surface. A novel, fully-automated post-processing includes physical model diagnostics like slab geometry, mantle flow pattern, upper-plate tilt angle and trench location.

  6. Radiological morphology of peritalar instability in varus and valgus tilted ankles.

    Science.gov (United States)

    Nosewicz, Tomasz L; Knupp, Markus; Bolliger, Lilianna; Henninger, Heath B; Barg, Alexej; Hintermann, Beat

    2014-05-01

    Varus and valgus talar tilt in weight-bearing ankles can be explained by loss of peritalar stability allowing the talus to shift and rotate on the calcaneal and navicular surfaces. Little is known about the underlying destabilization process or the resulting talar malpositions. The purpose of this study was to determine talar position in 3 radiographic planes of varus and valgus tilted ankles. Standard weight-bearing radiographs of 126 varus ankles (118 patients [mean age 62 ± 12 years]) and 81 valgus ankles (75 patients [mean age 65 ± 10 years]) were retrospectively evaluated. The tibiotalar surface angle, sagittal talocalcaneal inclination angle, and horizontal talometatarsal I angle were used to determine the frontal, sagittal, and horizontal position of the talus. A control group was used for comparison. Isolated talar varus malposition was found in 33.3% of the ankles (42/126), and malposition in 1 or both additional planes was found in 49.2% (62/126) and 17.5% (22/126), respectively. In valgus ankles, the percentages were 52% (42/81), 43% (35/81), and 5% (4/81), respectively. Seven out of 9 possible varus and 5 out of 9 possible valgus talar malposition configurations were found. The 4 predominant varus malposition configurations (89.7%, or 113/126) were dorsiflexion or neutral (sagittal plane) combined with neutral/external rotation and neutral/internal rotation (horizontal plane), respectively. The 3 predominant valgus malposition configurations (95%, or 77/81) were neutral or plantar flexion (sagittal plane) combined with neutral/external rotation and neutral (horizontal plane), respectively. In varus and valgus tilted ankles, talar frontal plane alignment does not predict talar sagittal and horizontal position, indicating that peritalar instability leads to various talar malpositions. Prior to operative treatment of varus and valgus tilted ankles, thorough 3-dimensional analysis of talar position may minimize failure in properly balancing the talus

  7. Ferroelectric and octahedral tilt twin disorder and the lead-free piezoelectric, sodium potassium niobate system

    International Nuclear Information System (INIS)

    Schiemer, Jason; Withers, Ray L.; Liu, Yun; Yi, Zhiguo

    2012-01-01

    Using electron diffraction, trends in the local structural behaviour of the K x Na 1−x NbO 3 (KNN x) ‘solid solution’ system are investigated and interpreted using an order/disorder based theoretical framework. At room temperature, electron diffraction shows a single plane of transverse polarised, diffuse intensity perpendicular to [0 1 0] p ⁎ (p for parent sub-structure) across the entire phase diagram, indicative of ferroelectric disorder along the [0 1 0] p direction co-existing with long range ferroelectric order along the orthogonal [1 0 0] p and [0 0 1] p directions. An additional characteristic pattern of diffuse scattering is also observed, involving rods of diffuse intensity running along the [1 0 0] p * and [0 0 1] p * directions of the perovskite sub-structure and indicative of octahedral tilt disorder about the [1 0 0] p and [0 0 1] p axes co-existing with long range ordered octahedral tilting around the [0 1 0] p direction. A possible crystal chemical explanation for the existence of this latter octahedral tilt disorder is explored through bond valence sum calculations. The possible influence of both types of disorder on the previously refined, room temperature space group/s and average crystal structure/s is examined. - Graphical abstract: [−3,0.−1]p zone axis EDP of K 0.46 Na 0.54 NbO 3 indexed according to both the relevant Pcm21 space groups (no subscripts) and the parent perovskite subcell (denoted by a subscript p). Highlights: ► Characterises ferroelectric and octahedral tilt disorder in the KNN solid solution. ► Discusses the possible driving forces for this disorder. ► Discusses the implications of this disorder for physical properties. ► Discusses the effects of this disorder on powder diffraction data.

  8. Control of Pan-tilt Mechanism Angle using Position Matrix Method

    Directory of Open Access Journals (Sweden)

    Hendri Maja Saputra

    2013-12-01

    Full Text Available Control of a Pan-Tilt Mechanism (PTM angle for the bomb disposal robot Morolipi-V2 using inertial sensor measurement unit, x-IMU, has been done. The PTM has to be able to be actively controlled both manually and automatically in order to correct the orientation of the moving Morolipi-V2 platform. The x-IMU detects the platform orientation and sends the result in order to automatically control the PTM. The orientation is calculated using the quaternion combined with Madwick and Mahony filter methods. The orientation data that consists of angles of roll (α, pitch (β, and yaw (γ from the x-IMU are then being sent to the camera for controlling the PTM motion (pan & tilt angles after calculating the reverse angle using position matrix method. Experiment results using Madwick and Mahony methods show that the x-IMU can be used to find the robot platform orientation. Acceleration data from accelerometer and flux from magnetometer produce noise with standard deviation of 0.015 g and 0.006 G, respectively. Maximum absolute errors caused by Madgwick and Mahony method with respect to Xaxis are 48.45º and 33.91º, respectively. The x-IMU implementation as inertia sensor to control the Pan-Tilt Mechanism shows a good result, which the probability of pan angle tends to be the same with yaw and tilt angle equal to the pitch angle, except a very small angle shift due to the influence of roll angle..

  9. Morphological classification of acromial spur: correlation between Rockwood tilt view and arthroscopic finding

    Directory of Open Access Journals (Sweden)

    Kongmalai Pinkawas

    2017-01-01

    Full Text Available Purpose and hypothesis: Acromion spur is the extrinsic factor for impingement syndrome and rotator cuff tear. The Rockwood tilt view can be used to evaluate prominence of the anterior acromion, however no study has shown the correlation of findings between the Rockwood tilt view and the arthroscopic finding. Methods: We developed the arthroscopic classification of acromion spur as type 1 flat spur, type 2 bump spur, type 3 heel spur, type 4 keel spur, and type 5 irregular spur. Patients with rotator cuff syndrome who underwent arthroscopic surgery were recruited. Two observers were asked to classify the type of spur from arthroscopic findings and Rockwood tilt views separately in random pattern. The prevalence of supraspinatus tendon tear was also recorded as no tear, partial-thickness tear, and full-thickness tear. Results: The keel spur (33.9% was the most common finding followed by the heel spur (27.8%. The correlation was high especially for the heel, the keel, and the irregular spur (75.47%, 74.03%, and 72.73%, respectively. These three types of spurs have a high prevalence of full thickness of supraspinatus tendon tear. Conclusion: The Rockwood tilt view can be used to evaluate the morphology of an acromion spur, especially the at-risk spur that correlates highly with the full-thickness supraspinatus tendon tear. The arthroscopic classification will also be a useful tool to improve communication between the surgeon and the guide for appropriate treatment in a rotator cuff tear patient when encountering the heel, keel, and irregular spur.

  10. Tilted Bianchi type-I wet dark fluid model in Saez and Ballester theory

    Science.gov (United States)

    Sahu, S. K.; Tole, T. T.; Balcha, M.

    2018-01-01

    Tilted Bianchi-I wet dark fluid cosmological model is investigated in Saez and Ballester scalar theory of gravitation. Background cosmologies are obtained for a constant deceleration parameter. We consider a linear relationship between the shear scalar and the expansion scalar. We have discussed some physical and geometrical properties of the models. In our models, equation of state of the dark energy is observed to behave like a cosmological constant at late times.

  11. Specifying tilts, decenters, and beam deviations using the new edition of ISO 10110-6

    Science.gov (United States)

    Williamson, Ray

    2017-08-01

    ISO 10110-6 has been the international standard for defining and notating tilt and decenter within optical elements. The increasing sophistication of optical componentry and systems, driven largely by new design and fabrication capabilities, made clear the need for an expansion of that document. This paper introduces the contexts, reviews the concepts related to optical centration, and describes the notation system within the 2015 edition of the document.

  12. Safety and tolerability of Tilt Testing and Carotid Sinus Massage in the octogenarians

    OpenAIRE

    KENNY, ROSE

    2016-01-01

    Objective: to evaluate the safety and tolerability of Tilt Testing (TT) and Carotid Sinus Massage (CSM) in octogenarians with unexplained syncope. Methods: patients consecutively referred for transient loss of consciousness to the ‘Syncope Units’ of three hospitals were enrolled. TT and CSM were performed according to the European Society of Cardiology guidelines on syncope. Complications were evaluated in each group. An early interruption of TT was defined as ‘intolerance’ and considered...

  13. Mechatronic development of an active spring-/tilt engineering for the railcar RailCab

    International Nuclear Information System (INIS)

    Liu-Henke, X.

    2005-01-01

    A mechatronic development process with computer-supported design up to real time implementation of a prototype was applied throughout, with particular emphasis on mechatronic composition. After establishing a nonlinear mechatronic model and model identification, nonlinear compensation was designed and implemented in a HiL test stand. Simulations and test stand measurements verified high driving comfort and high safety as a result of the implemented active spring/tilt technology

  14. Six-implant-supported immediate fixed rehabilitation of atrophic edentulous maxillae with tilted distal implants.

    Science.gov (United States)

    Wentaschek, S; Hartmann, S; Walter, C; Wagner, W

    2017-12-01

    The aim of this retrospective study was to evaluate the treatment outcome of six Bredent blueSky™ implants (Bredent GmbH, Senden, Germany) immediately loaded with a fixed full-arch prosthesis (two tilted posterior and four axial frontal and premolar implants). All 10 patients with atrophic edentulous maxillae being treated with a standardized procedure from 09/2009 to 01/2013, who had a follow-up of at least 3 years, were included. Sixty implants were placed to support 10 screwed prostheses. Twenty-one of them were inserted in fresh extraction sockets. Lab-side-prepared provisional fixed prostheses were placed at the day of implantation. Periotest (PT) values and implant stability quotient (ISQ) were measured after implant surgery and after 3 months of healing in all patients. The analyzed implants were in function in mean 64 ± 13 months (range 42 to 84 months). One axial and two tilted implants failed in three patients. The mean PT values decreased, and ISQ increased significantly after the first 3 months at the osseointegrated tilted and axial implants. With an area under the curve of 0.503 and 0.506 in the receiver operating characteristic, the PT values and the ISQ were unspecific parameters and unsuitable as a predictor for the risk of non-osseointegration. Within the limits of this small group (n = 10 patients/60 implants), the failure rate of the analyzed implant system (n = 3 respective 5% implant loss) seems to be comparable with other immediate-loading protocols. The failure rate of tilted implants in the atrophic upper jaw was quite high, but the aimed treatment concept could be achieved in every patient. The rehabilitation of the posterior region in edentulous maxilla remains a challenge.

  15. Tilt-table testing of patients with pacemaker and recurrent syncope

    DEFF Research Database (Denmark)

    Nielsen, Christian E. Haarmark; Kanters, Jørgen K; Mehlsen, Jesper

    2016-01-01

    The diagnosis of recurrent syncope in patients with pacemakers (PM) is quite challenging and the etiology of syncope is often multifactorial. To portray the mechanism of syncope in PM patients, we report the results of head-up tilt table testing (HUT) in a series of patients with PM, originally...... with pacemakers has a high diagnostic yield. Although, the majority of patients had a vasodepressor or orthostatic hypotensive response, cardioinhibitory response leading to syncope was also seen....

  16. The sensitivity of the bielschowsky head-tilt test in diagnosing acquired bilateral superior oblique paresis.

    Science.gov (United States)

    Muthusamy, Brinda; Irsch, Kristina; Peggy Chang, Han-Ying; Guyton, David L

    2014-04-01

    To determine the sensitivity of the Bielschowsky head-tilt test and other commonly used criteria in identifying patients with true bilateral superior oblique paresis. A retrospective chart review was performed to identify patients seen between 1978 and 2009 who were diagnosed with acquired bilateral superior oblique paresis. All patients had a confirmed history of head trauma or brain surgery with altered consciousness followed by symptomatic diplopia. Bilateral superior oblique paresis was defined and diagnosed by the above history, including the presence of greater extorsion in downgaze than upgaze on Lancaster red-green testing, a V-pattern strabismus, and bilateral fundus extorsion. We analyzed findings of the Bielschowsky head-tilt test, the Parks 3-step test, and reversal of the hypertropia from straight-ahead gaze to the other 8 diagnostic positions of gaze to determine these tests' sensitivity in identifying true bilateral superior oblique paresis. Twenty-five patients were identified with the diagnosis of true bilateral superior oblique paresis. The Bielschowsky head-tilt test had a 40% sensitivity, the Parks 3-step test had a sensitivity of 24%, and reversal of the hypertropia had a sensitivity of 60% in making the diagnosis of true bilateral superior oblique paresis. What previously has been described as masked bilateral superior oblique paresis simply may be a reflection of inherent poor sensitivity of the Bielschowsky head-tilt test, the Parks 3-step test, and reversal of the hypertropia in diagnosing bilateral superior oblique paresis. Hence, none of these tests should be relied on exclusively to make this diagnosis. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Adaptive Neural Network Sliding Mode Control for Quad Tilt Rotor Aircraft

    OpenAIRE

    Yanchao Yin; Hongwei Niu; Xiaobao Liu

    2017-01-01

    A novel neural network sliding mode control based on multicommunity bidirectional drive collaborative search algorithm (M-CBDCS) is proposed to design a flight controller for performing the attitude tracking control of a quad tilt rotors aircraft (QTRA). Firstly, the attitude dynamic model of the QTRA concerning propeller tension, channel arm, and moment of inertia is formulated, and the equivalent sliding mode control law is stated. Secondly, an adaptive control algorithm is presented to eli...

  18. Line Tension and Interaction Energies of Membrane Rafts Calculated from Lipid Splay and Tilt

    OpenAIRE

    Kuzmin, Peter I.; Akimov, Sergey A.; Chizmadzhev, Yuri A.; Zimmerberg, Joshua; Cohen, Fredric S.

    2004-01-01

    Membrane domains known as rafts are rich in cholesterol and sphingolipids, and are thought to be thicker than the surrounding membrane. If so, monolayers should elastically deform so as to avoid exposure of hydrophobic surfaces to water at the raft boundary. We calculated the energy of splay and tilt deformations necessary to avoid such hydrophobic exposure. The derived value of energy per unit length, the line tension γ, depends on the elastic moduli of the raft and the surrounding membrane;...

  19. Two-dimensional FSI simulation of closing dynamics of a tilting disc mechanical heart valve.

    Science.gov (United States)

    Govindarajan, V; Udaykumar, H S; Herbertson, L H; Deutsch, S; Manning, K B; Chandran, K B

    2010-03-01

    The fluid dynamics during valve closure resulting in high shear flows and large residence times of particles has been implicated in platelet activation and thrombus formation in mechanical heart valves. Our previous studies with bi-leaflet valves have shown that large shear stresses induced in the gap between the leaflet edge and the valve housing results in relatively high platelet activation levels whereas flow between the leaflets results in shed vortices not conducive to platelet damage. In this study we compare the result of closing dynamics of a tilting disc valve with that of a bi-leaflet valve. The two-dimensional fluid-structure interaction analysis of a tilting disc valve closure mechanics is performed with a fixed grid Cartesian mesh flow solver with local mesh refinement, and a Lagrangian particle dynamic analysis for computation of potential for platelet activation. Throughout the simulation the flow remains in the laminar regime and the flow through the gap width is marked by the development of a shear layer which separates from the leaflet downstream of the valve. Zones of re-circulation are observed in the gap between the leaflet edge and the valve housing on the major orifice region of the tilting disc valve and are seen to be migrating towards the minor orifice region. Jet flow is observed at the minor orifice region and a vortex is formed which sheds in the direction of fluid motion as observed in experiments using PIV measurements. The activation parameter computed for the tilting disc valve, at the time of closure was found to be 2.7 times greater than that of the bi-leaflet mechanical valve and was found to be in the vicinity of the minor orifice region mainly due to the migration of vortical structures from the major to the minor orifice region during the leaflet rebound of the closing phase.

  20. Introducer Curving Technique for the Prevention of Tilting of Transfemoral Gunther Tulip Inferior Vena Cava Filter

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Liang; Shen, Jing; Tong, Jia Jie [The First Hospital of China Medical University, Shenyang (China); Huang, De Sheng [College of Basic Medical Science, China Medical University, Shenyang (China)

    2012-07-15

    To determine whether the introducer curving technique is useful in decreasing the degree of tilting of transfemoral Tulip filters. The study sample group consisted of 108 patients with deep vein thrombosis who were enrolled and planned to undergo thrombolysis, and who accepted transfemoral Tulip filter insertion procedure. The patients were randomly divided into Group C and Group T. The introducer curving technique was Adopted in Group T. The post-implantation filter tilting angle (ACF) was measured in an anteroposterior projection. The retrieval hook adhering to the vascular wall was measured via tangential cavogram during retrieval. The overall average ACF was 5.8 {+-} 4.14 degrees. In Group C, the average ACF was 7.1 {+-} 4.52 degrees. In Group T, the average ACF was 4.4 {+-} 3.20 degrees. The groups displayed a statistically significant difference (t = 3.573, p = 0.001) in ACF. Additionally, the difference of ACF between the left and right approaches turned out to be statistically significant (7.1 {+-} 4.59 vs. 5.1 {+-} 3.82, t = 2.301, p = 0.023). The proportion of severe tilt (ACF {>=} 10 degree) in Group T was significantly lower than that in Group C (9.3% vs. 24.1%, X{sup 2} = 4.267, p = 0.039). Between the groups, the difference in the rate of the retrieval hook adhering to the vascular wall was also statistically significant (2.9% vs. 24.2%, X{sup 2} = 5.030, p = 0.025). The introducer curving technique appears to minimize the incidence and extent of transfemoral Tulip filter tilting.

  1. Introducer Curving Technique for the Prevention of Tilting of Transfemoral Gunther Tulip Inferior Vena Cava Filter

    International Nuclear Information System (INIS)

    Xiao, Liang; Shen, Jing; Tong, Jia Jie; Huang, De Sheng

    2012-01-01

    To determine whether the introducer curving technique is useful in decreasing the degree of tilting of transfemoral Tulip filters. The study sample group consisted of 108 patients with deep vein thrombosis who were enrolled and planned to undergo thrombolysis, and who accepted transfemoral Tulip filter insertion procedure. The patients were randomly divided into Group C and Group T. The introducer curving technique was Adopted in Group T. The post-implantation filter tilting angle (ACF) was measured in an anteroposterior projection. The retrieval hook adhering to the vascular wall was measured via tangential cavogram during retrieval. The overall average ACF was 5.8 ± 4.14 degrees. In Group C, the average ACF was 7.1 ± 4.52 degrees. In Group T, the average ACF was 4.4 ± 3.20 degrees. The groups displayed a statistically significant difference (t = 3.573, p = 0.001) in ACF. Additionally, the difference of ACF between the left and right approaches turned out to be statistically significant (7.1 ± 4.59 vs. 5.1 ± 3.82, t = 2.301, p = 0.023). The proportion of severe tilt (ACF ≥ 10 degree) in Group T was significantly lower than that in Group C (9.3% vs. 24.1%, X 2 = 4.267, p = 0.039). Between the groups, the difference in the rate of the retrieval hook adhering to the vascular wall was also statistically significant (2.9% vs. 24.2%, X 2 = 5.030, p = 0.025). The introducer curving technique appears to minimize the incidence and extent of transfemoral Tulip filter tilting.

  2. Using Concurrent Cardiovascular Information to Augment Survival Time Data for Evaluating Orthostatic Tilt Test Performance

    Science.gov (United States)

    Feiveson, Alan H.; Fiedler, James; Lee, Stuart M. C.; Koslovsky, Matthew D.; Stenger, Michael B.; Platts, Steven H.

    2018-01-01

    Head-up tilt (HUT) tests often are used in research to measure orthostatic intolerance (OI) (inability to appropriately control blood pressure while upright) in clinical populations and otherwise healthy individuals after interventions. Post-space flight orthostatic intolerance is a well-known phenomenon, and countermeasures to its development has been an active area of research at NASA. In the NASA HUT protocol, subjects lie horizontally on an automatic tilt table for baseline measurements before being raised to 80deg head-up tilt for a defined period of time or until signs or symptoms of presyncope ensues (light-headedness, nausea, dizziness, sweating, weakness or fainting). Multiple measures are collected to evaluate the cardiovascular system's ability to respond appropriately to the orthostatic challenge. However if the intended duration of the HUT is short, the ability to detect changes in OI due to an intervention or its prevention by a countermeasure may be limited by a small number of failures to permit comparisons based on survival time alone. Thus, the time-trajectory of the cardiovascular data becomes an important additional source of information. In particular, we will show how various measures of trajectory variability can effectively augment survival analysis for the assessment of OI in a joint model when high censoring rates are present.

  3. Formation of precessing jets by tilted black hole discs in 3D general relativistic MHD simulations

    Science.gov (United States)

    Liska, M.; Hesp, C.; Tchekhovskoy, A.; Ingram, A.; van der Klis, M.; Markoff, S.

    2018-02-01

    Gas falling into a black hole (BH) from large distances is unaware of BH spin direction, and misalignment between the accretion disc and BH spin is expected to be common. However, the physics of tilted discs (e.g. angular momentum transport and jet formation) is poorly understood. Using our new GPU-accelerated code H-AMR, we performed 3D general relativistic magnetohydrodynamic simulations of tilted thick accretion discs around rapidly spinning BHs, at the highest resolution to date. We explored the limit where disc thermal pressure dominates magnetic pressure, and showed for the first time that, for different magnetic field strengths on the BH, these flows launch magnetized relativistic jets propagating along the rotation axis of the tilted disc (rather than of the BH). If strong large-scale magnetic flux reaches the BH, it bends the inner few gravitational radii of the disc and jets into partial alignment with the BH spin. On longer time-scales, the simulated disc-jet system as a whole undergoes Lense-Thirring precession and approaches alignment, demonstrating for the first time that jets can be used as probes of disc precession. When the disc turbulence is well resolved, our isolated discs spread out, causing both the alignment and precession to slow down.

  4. Shared computational mechanism for tilt compensation accounts for biased verticality percepts in motion and pattern vision.

    Science.gov (United States)

    De Vrijer, M; Medendorp, W P; Van Gisbergen, J A M

    2008-02-01

    To determine the direction of object motion in external space, the brain must combine retinal motion signals and information about the orientation of the eyes in space. We assessed the accuracy of this process in eight laterally tilted subjects who aligned the motion direction of a random-dot pattern (30% coherence, moving at 6 degrees /s) with their perceived direction of gravity (motion vertical) in otherwise complete darkness. For comparison, we also tested the ability to align an adjustable visual line (12 degrees diameter) to the direction of gravity (line vertical). For small head tilts (60 degrees revealed a pattern of large systematic errors (often >30 degrees ) that was virtually identical in both tasks. Regression analysis confirmed that mean errors in the two tasks were closely related, with slopes close to 1.0 and correlations >0.89. Control experiments ruled out that motion settings were based on processing of individual single-dot paths. We conclude that the conversion of both motion direction and line orientation on the retina into a spatial frame of reference involves a shared computational strategy. Simulations with two spatial-orientation models suggest that the pattern of systematic errors may be the downside of an optimal strategy for dealing with imperfections in the tilt signal that is implemented before the reference-frame transformation.

  5. No evidence for the blue-tilted power spectrum of relic gravitational waves

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qing-Guo; Wang, Sai, E-mail: huangqg@itp.ac.cn, E-mail: wangsai@itp.ac.cn [State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Science, Beijing 100190 (China)

    2015-06-01

    In this paper, we constrain the tilt of the power spectrum of relic gravitational waves by combining the data from BICEP2/Keck Array and Planck (BKP) and the Laser Interferometer Gravitational-Waves Observatory (LIGO). Supposing the linearly uniform priors for both the tensor-to-scalar ratio r and the tensor tilt n{sub t}, we find n{sub t}=0.66{sup +1.83}{sub −1.44} at the 68% confidence level from the data of BKP B-modes. By further adding the LIGO upper limit on the intensity of stochastic gravitational-wave background, the constraint becomes n{sub t}=−0.76{sup +1.37}{sub −0.52} at the 68% confidence level by assuming that the tensor amplitude has the similar order of the upper bounds from current CMB experiments. We find that there is no evidence for a blue-tilted power spectrum of relic gravitational waves and either sign of the index of tensor power spectrum is compatible with the current data.

  6. [THE EFFECTS OF THE PILATES METHOD ON HAMSTRING EXTENSIBILITY, PELVIC TILT AND TRUNK FLEXION].

    Science.gov (United States)

    Vaquero-Cristóbal, Raquel; López-Miñarro, Pedro A; Alacid Cárceles, Fernando; Esparza-Ros, Francisco

    2015-11-01

    Pilates includes a high volume of hamstring stretching and maximal trunk flexion with knees extended exercises. to perform a systematic review about Pilates practice effects and a detraining period on hamstring extensibility, pelvic tilt and trunk flexion in maximal trunk flexion with knees extended. it was analysed all the experimental or quasi-experimental designs written in English, Spanish or Portuguese and included in the following databases: Pubmed, Sports Discus, ISI Web of Knowledge, Dialnet and Research Gate. twenty-one papers were analysed. Most of them used a pre-test-post-test design with control group. The intervention programs applied were heterogeneous. Samples were composed mainly of women, both young and old. It was found that the Pilates practice, with different volume, significantly increased hamstring muscle extensibility and pelvic tilt in maximal trunk flexion. At least three training sessions peer week during six weeks were necessary in order to obtain a high trunk inclination. Studies which involved athletes showed contradictory results. By inducing a detraining period it was noticed a decrease in hamstring extensibility and trunk flexion from the second week. there is a moderate evidence that Pilates is an effective method to increase hamstring extensibility, pelvic tilt and the degree of trunk flexion in maximal flexion positions in sedentary and recreational active people and also to increase hamstring extensibility in athletes. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

  7. MODELLING AND CONTROL OF H-SHAPED RACING QUADCOPTER WITH TILTING PROPELLERS

    Directory of Open Access Journals (Sweden)

    Ahmed Alkamachi

    2017-08-01

    Full Text Available Traditional quadcopter suffers terribly from its underactuation which implies the coupling between the rotational and the translational motion. In this paper, we present a quadcopter with dynamic rotor tilting capability in which the four propellers are allowed to tilt together around their arm axis. The proposed model provides leveled forward/backward horizontal motion and therefore, ensures a correct view of the onboard camera, and increases the vehicle speed by reducing the air drag. The rotor tilt mechanism also provides an instant high speed in the forward or reverse direction and offers a quick and solid air brake to restrain that fast moving speed.  The nonlinear dynamical model for the quadcopter under consideration is derived using Newton-Euler formalization. A control strategy is then proposed aimed to control the altitude, attitude, and the forward speed of the obtained model. Finally, a numerical simulation is used to integrate the system model with the controller and to test the system performance. Simulation results are reported to demonstrate the advantages of the proposed novel configuration.

  8. Vortex bending in a tilted YBa2Cu3O7-δ crystal

    Science.gov (United States)

    Obaidat, I. M.; Park, S. J.; Safar, H.; Kouvel, J. S.

    1997-09-01

    Magnetization-vector measurements were made on a YBa2Cu3O7-δ crystal, initially cooled to 4.2 K in an external field He parallel to the c axis. With He fixed, the crystal was then tilted, such that the angle θ between the c axis and He was gradually raised to 90° and lowered back to zero. Our results reveal that all the vortex flux remains parallel to the c axis until the tilt angle θ reaches a threshold value (close to 15° for Hevalue, the vortex flux in the ab plane rises rapidly from zero, and it appears to derive solely from a bending of the vortices initially directed along c. This whole process is fairly consistent with theoretical predictions, and it is found to be essentially reversible with the cycling of θ at low He. The hysteresis that develops at higher He rises and approaches the conventional hysteresis measured along ab after zero-field cooling. Comparison is also made with a cross-flux experiment, which is seen to be only superficially equivalent to the crystal-tilt experiment.

  9. Evaluating solar radiation on a tilted surfaces - a study case in Timis (Romania)

    International Nuclear Information System (INIS)

    Vasar, C; Prostean, O; Prostean, G

    2016-01-01

    In the last years the usage of solar energy has grown considerably in Romania, as well as in Europe, stimulated by various factors as government programs, green pricing policies, decreasing of photovoltaic components cost etc. Also, the rising demand of using Solar Energy Conversion Systems (SECS) is driven by the desire of individuals or companies to obtain energy from a clean renewable source. In many applications, remote consumers far from other energetic grids can use solar systems more cost-effectively than extending the grid to reach the location. Usually the solar energy is measured or forecast on horizontal surface, but in SECS there is needed the total solar radiation incident on the collector surface, that is oriented in a position that maximize the harvested energy. There are many models that convert the solar radiation from horizontal surface to a tilted surface, but they use empirical coefficients and the accuracy is influenced by different facts as geographical location or sky conditions. Such models were used considering measured values for solar radiation on horizontal plane, in the western part of Romania. Hourly values measured for global solar irradiation on the horizontal plane, diffuse solar irradiation on the horizontal plane and reflected solar irradiation by ground are used to compute the total solar radiation incident on different tilted surfaces. The calculated incident radiation is then compared with the real radiation measured on tilted surface in order to evaluate the performance of the considered conversion models. (paper)

  10. Exercise thermoregulation in men after 1 and 24-hours of 6 degrees head-down tilt

    Science.gov (United States)

    Ertl, A. C.; Dearborn, A. S.; Weidhofer, A. R.; Bernauer, E. M.; Greenleaf, J. E.

    2000-01-01

    BACKGROUND: Exercise thermoregulation is dependent on heat loss by increased skin blood flow (convective and conductive heat loss) and through enhanced sweating (evaporative heat loss). Reduction of plasma volume (PV), increased plasma osmolality, physical deconditioning, and duration of exposure to simulated and actual microgravity reduces the ability to thermoregulate during exercise. HYPOTHESIS: We hypothesized that 24 h of head down tilt (HDT24) would alter thermoregulatory responses to a submaximal exercise test and result in a higher exercise rectal temperature (Tre) when compared with exercise Tre after 1 h of head down tilt (HDT1). METHODS: Seven men (31+/-SD 6 yr, peak oxygen uptake (VpO2peak) of 44+/-6 ml x kg(-1) x min(-1)) were studied during 70 min of supine cycling at 58+/-SE 1.5% VO2peak at 22.0 degrees C Tdb and 47% rh. RESULTS: Relative to pre-tilt sitting chair rest data, HDT1 resulted in a 6.1+/-0.9% increase and HDT24 in a 4.3+/-2.3% decrease in PV (delta = 10.4% between experiments, pthermoregulation), the Tre offset could have been caused by the HDT-induced hypovolemia.

  11. Conductance modulation in Weyl semimetals with tilted energy dispersion without a band gap

    Science.gov (United States)

    Yesilyurt, Can; Siu, Zhuo Bin; Tan, Seng Ghee; Liang, Gengchiau; Jalil, Mansoor B. A.

    2017-06-01

    We investigate the tunneling conductance of Weyl semimetal with tilted energy dispersion by considering electron transmission through a p-n-p junction with one-dimensional electric and magnetic barriers. In the presence of both electric and magnetic barriers, we found that a large conductance gap can be produced with the aid of tilted energy dispersion without a band gap. The origin of this effect is the shift of the electron wave-vector at barrier boundaries caused by (i) the pseudo-magnetic field induced by electrical potential, i.e., a newly discovered feature that is only possible in the materials possessing tilted energy dispersion, (ii) the real magnetic field induced by a ferromagnetic layer deposited on the top of the system. We use a realistic barrier structure applicable in current nanotechnology and analyze the temperature dependence of the tunneling conductance. The new approach presented here may resolve a major problem of possible transistor applications in topological semimetals, i.e., the absence of normal backscattering and gapless band structure.

  12. Tonic ocular tilt reaction simulating a superior oblique palsy: diagnostic confusion with the 3-step test.

    Science.gov (United States)

    Donahue, S P; Lavin, P J; Hamed, L M

    1999-03-01

    The tonic ocular tilt reaction (OTR) consists of vertical divergence of the eyes (skew deviation), bilateral conjugate ocular torsion, and paradoxical head tilt. The head and superior pole of both eyes are rotated toward the hypotropic eye. To describe ocular motility and torsion findings in 5 patients with OTRs that mimicked superior oblique palsies (SOPs). In 5 patients, results of the 3-step test suggested an SOP (bilateral in 1 patient); however, no patient had the expected excyclotorsion of the hypertropic eye. Two patients had conjugate ocular torsion (intorsion of the hypertropic eye and extorsion of the hypotropic eye), and 2 patients had only intorsion of the hypertropic eye. All had other neurologic features consistent with more widespread brainstem disease. Vertical ocular deviations that 3-step to an SOP are not always caused by fourth nerve weakness. When a patient with an apparent fourth nerve palsy has ocular torsion that is inconsistent with an SOP, OTR should be suspected, especially if vestibular system or posterior fossa dysfunction coexists. The rules for the 3-step test for an SOP may be fulfilled by damaging the otolithic projections corresponding to projections of the contralateral anterior semicircular canal. Because results of the Bielschowsky head tilt test may be positive in patients with the OTR, the feature distinguishing OTR from an SOP is the direction of torsion. We advocate use of a fourth step-evaluation of ocular torsion-in addition to the standard 3 steps.

  13. The relationship between anterior pelvic tilt and gait, balance in patient with chronic stroke.

    Science.gov (United States)

    Kim, Myoung-Kwon; Kim, Seong-Gil; Shin, Young-Jun; Choi, Eun-Hong; Choe, Yu-Won

    2018-01-01

    [Purpose] The aim of this study is to find out the association between anterior pelvic tilt and gait and balance in chronic stroke. [Subjects and Methods] Fourteen chronic stroke patients were included in this study. A palpation meter was employed to measure the anterior inclination of the pelvis. A GAITRite system automates measuring temporal and spatial gait parameters. A 10-Meter Walk test was used to measure gait speed. The Timed Up and Go test was used to measure the dynamic balance ability and gait ability of the participants. A BioRescue was used to assess balance by measuring the moving distance and area of the center of pressure. [Results] There were significant negative correlations between pelvic anterior tilt and velocity, step length, and stride. There were significant positive correlations between velocity and cadence, step length, and stride length. There were significant negative correlations between velocity and cycle time, H-H base, TUG, and 10MWT. There was significant negative correlation between cadence and cycle time and H-H base. [Conclusion] This study showed a negative correlation between pelvic anterior tilt and gait function including gait speed and step length.

  14. Aberration analysis for freeform surface terms overlay on general decentered and tilted optical surfaces.

    Science.gov (United States)

    Yang, Tong; Cheng, Dewen; Wang, Yongtian

    2018-03-19

    Aberration theory helps designers to better understand the nature of imaging systems. However, the existing aberration theory of freeform surfaces has many limitations. For example, it only works in the special case when the central area of the freeform surface is used. In addition, the light footprint is limited to a circle, which does not match the case of an elliptical footprint for general systems. In this paper, aberrations generated by freeform surface term overlay on general decentered and tilted optical surfaces are analyzed. For the case when the off-axis section of a freeform surface is used, the aberration equation for using stop and nonstop surfaces is discussed, and the aberrations generated by Zernike terms up to Z 17/18 are analyzed in detail. To solve the problem of the elliptical light footprint for tilted freeform surfaces, the scaled pupil vector is used in the aberration analysis. The mechanism of aberration transformation is discovered, and the aberrations generated by different Zernike terms in this case are calculated. Finally we proposed aberration equations for freeform terms on general decentered and tilted freeform surfaces. The research result given in this paper offers an important reference for optical designers and engineers, and it is of great importance in developing analytical methods for general freeform system design, tolerance analysis, and system assembly.

  15. System analysis of a tilted field-widened Michelson interferometer for high spectral resolution lidar.

    Science.gov (United States)

    Liu, Dong; Hostetler, Chris; Miller, Ian; Cook, Anthony; Hair, Johnathan

    2012-01-16

    High spectral resolution lidars (HSRLs) have shown great value in aircraft aerosol remote sensing application and are planned for future satellite missions. A compact, robust, quasi-monolithic tilted field-widened Michelson interferometer is being developed as the spectral discrimination filter for an second-generation HSRL(HSRL-2) at NASA Langley Research Center. The Michelson interferometer consists of a cubic beam splitter, a solid arm and an air arm. Piezo stacks connect the air arm mirror to the body of the interferometer and can tune the interferometer within a small range. The whole interferometer is tilted so that the standard Michelson output and the reflected complementary output can both be obtained. In this paper, the transmission ratio is proposed to evaluate the performance of the spectral filter for HSRL. The transmission ratios over different types of system imperfections, such as cumulative wavefront error, locking error, reflectance of the beam splitter and anti-reflection coatings, system tilt, and depolarization angle are analyzed. The requirements of each imperfection for good interferometer performance are obtained.

  16. Electromagnetically Driven Dual-axis Tilting MEMS Grating for Near Infrared Spectroscopy

    Science.gov (United States)

    Watanabe, Yoshiyuki; Takahashi, Yoshiyuki; Abe, Yutaka; Iwamatsu, Shinnosuke; Yahagi, Toru; Kobayashi, Seiya; Konno, Shunsuke; Sato, Toshiyuki

    This paper describes design and fabrication of electromagnetically driven dual-axis tilting MEMS-grating, and evaluation for low coherent near infrared spectroscopy. At first, we have investigated fabrication of laminar grating using EB lithography of UV photoresist and dry etching of silicon. In consequence, the laminar gratings of 0.6 - 2.0μm pitches were fabricated successfully. Second, we fabricated electromagnetically driven MEMS-grating which can tilt to dual-axis. Primary axis is used for spectroscopy, and the secondary axis is used for optical axis alignment. As the results of evaluation, primary and secondary DC tilting angles were 0.40°/mA and 0.39°/mA, respectively. And then, primary and secondary resonant frequencies (Q-factor) were 217Hz (Q36) and 172Hz (Q25), respectively. Finally, we constructed Fourier domain fiber interferometer whose sample arm was 2m in length. As setting optical length difference to be 180μm, the interference spectrum in wavelength range of 1400-1700nm was observed in less than 25ms by MEMS-GR, and a Fourier and axis transformed peak was acquired at 50dB.

  17. Analysis of slippery droplet on tilted plate by development of optical correction method

    Science.gov (United States)

    Ko, Han Seo; Gim, Yeonghyeon; Choi, Sung Ho; Jang, Dong Kyu; Sohn, Dong Kee

    2017-11-01

    Because of distortion effects on a surface of a sessile droplet, the inner flow field of the droplet is measured by a PIV (particle image velocimetry) method with low reliability. In order to solve this problem, many researchers have studied and developed the optical correction method. However, the method cannot be applied for various cases such as the tilted droplet or other asymmetric shaped droplets since most methods were considered only for the axisymmetric shaped droplets. For the optical correction of the asymmetric shaped droplet, the surface function was calculated by the three-dimensional reconstruction using the ellipse curve fitting method. Also, the optical correction using the surface function was verified by the numerical simulation. Then, the developed method was applied to reconstruct the inner flow field of the droplet on the tilted plate. The colloidal droplet of water on the tilted surface was used, and the distorted effect on the surface of the droplet was calculated. Using the obtained results and the PIV method, the corrected flow field for the inner and interface parts of the droplet was reconstructed. Consequently, the error caused by the distortion effect of the velocity vector located on the apex of the droplet was removed. National Research Foundation (NRF) of Korea, (2016R1A2B4011087).

  18. An Analysis of Source Tilting and Sub-cell Opacity Sampling for IMC

    Energy Technology Data Exchange (ETDEWEB)

    Wollaeger, Ryan T. [Los Alamos National Laboratory; Urbatsch, Todd J. [Los Alamos National Laboratory; Wollaber, Allan B. [Los Alamos National Laboratory; Densmore, Jeffery D. [Los Alamos National Laboratory

    2012-08-02

    Implicit Monte Carlo (IMC) is a stochastic method for solving the radiative transfer equations for multiphysics application with the material in local thermodynamic equilibrium. The IMC method employs a fictitious scattering term that is computed from an implicit discretization of the material temperature equation. Unfortunately, the original histogram representation of the temperature and opacity with respect to the spatial domain leads to nonphysically fast propagation of radiation waves through optically thick material. In the past, heuristic source tilting schemes have been used to mitigate the numerical teleportation error of the radiation particles in IMC that cause this overly rapid radiation wave propagation. While improving the material temperature profile throughout the time duration, these tilting schemes alone do not generally alleviate the teleportation error to suitable levels. Another means of potentially reducing teleportation error in IMC is implementing continuous sub-cell opacities based on sub-cell temperature profiles. We present here an analysis of source tilting and continuous sub-cell opacity sampling applied to various discretizations of the temperature equation. Through this analysis, we demonstrate that applying both heuristics does not necessarily yield more accurate results if the discretization of the material equation is inconsistent with the Monte Carlo sub-cell transport.

  19. Effects of tilted angle of Bragg facets on the performance of successive strips based Bragg concave diffraction grating

    Science.gov (United States)

    Du, Bingzheng; Zhu, Jingping; Mao, Yuzheng; Wang, Kai; Chen, Huibing; Hou, Xun

    2018-03-01

    The effects of the tilted angle of facets on the diffraction orders, diffraction spectra, dispersion power, and the neighbor channel crosstalk of successive etching strips based Bragg concave diffraction grating (Bragg-CDG) are studied in this paper. The electric field distribution and diffraction spectra of four Bragg-CDGs with different tilted angles are calculated by numerical simulations. With the reflection condition of Bragg facets constant, the blazing order cannot change with the titled angle. As the tilted angle increases, the number of diffraction orders of Bragg-CDG will decrease, thereby concentrating more energy on the blazing order and improving the uniformity of diffraction spectra. In addition, the dispersion power of Bragg-CDG can be improved and the neighbor channel crosstalk of devices can be reduced by increasing the tilted angle. This work is beneficial to optimize the performance of Bragg-CDG.

  20. Remote sensing of a NTC radio source from a Cluster tilted spacecraft pair

    Directory of Open Access Journals (Sweden)

    P. M. E. Décréau

    2013-11-01

    Full Text Available The Cluster mission operated a "tilt campaign" during the month of May 2008. Two of the four identical Cluster spacecraft were placed at a close distance (~50 km from each other and the spin axis of one of the spacecraft pair was tilted by an angle of ~46°. This gave the opportunity, for the first time in space, to measure global characteristics of AC electric field, at the sensitivity available with long boom (88 m antennas, simultaneously from the specific configuration of the tilted pair of satellites and from the available base of three satellites placed at a large characteristic separation (~1 RE. This paper describes how global characteristics of radio waves, in this case the configuration of the electric field polarization ellipse in 3-D-space, are identified from in situ measurements of spin modulation features by the tilted pair, validating a novel experimental concept. In the event selected for analysis, non-thermal continuum (NTC waves in the 15–25 kHz frequency range are observed from the Cluster constellation placed above the polar cap. The observed intensity variations with spin angle are those of plane waves, with an electric field polarization close to circular, at an ellipticity ratio e = 0.87. We derive the source position in 3-D by two different methods. The first one uses ray path orientation (measured by the tilted pair combined with spectral signature of magnetic field magnitude at source. The second one is obtained via triangulation from the three spacecraft baseline, using estimation of directivity angles under assumption of circular polarization. The two results are not compatible, placing sources widely apart. We present a general study of the level of systematic errors due to the assumption of circular polarization, linked to the second approach, and show how this approach can lead to poor triangulation and wrong source positioning. The estimation derived from the first method places the NTC source region in the

  1. Mathematical Model and Analysis of the Water-Lubricated Hydrostatic Journal Bearings considering the Translational and Tilting Motions

    Directory of Open Access Journals (Sweden)

    Hui-Hui Feng

    2014-01-01

    Full Text Available The water-lubricated bearings have been paid attention for their advantages to reduce the power loss and temperature rise and increase load capacity at high speed. To fully study the complete dynamic coefficients of two water-lubricated, hydrostatic journal bearings used to support a rigid rotor, a four-degree-of-freedom model considering the translational and tilting motion is presented. The effects of tilting ratio, rotary speed, and eccentricity ratio on the static and dynamic performances of the bearings are investigated. The bulk turbulent Reynolds equation is adopted. The finite difference method and a linear perturbation method are used to calculate the zeroth- and first-order pressure fields to obtain the static and dynamic coefficients. The results suggest that when the tilting ratio is smaller than 0.4 or the eccentricity ratio is smaller than 0.1, the static and dynamic characteristics are relatively insensitive to the tilting and eccentricity ratios; however, for larger tilting or eccentricity ratios, the tilting and eccentric effects should be fully considered. Meanwhile, the rotary speed significantly affects the performance of the hydrostatic, water-lubricated bearings.

  2. Coherent tilt signals observed in the Shumagin seismic gap Detection of time-dependent subduction at depth?

    Science.gov (United States)

    Beavan, J.; Bilham, R.; Hurst, K.

    1984-01-01

    Repeated surveys of short level lines in the Shumagin Islands, Alaska, reveal coherent tilt signals associated with subduction of the Pacific plate beneath the North American plate in the Shumagin seismic gap. Ten years of steady tilt down toward the trench is interrupted during 1978-1980 by a rapid episode of reverse tilt. The 'normal' tilt represents surface deformation as subduction occurs, with the plate boundary locked to at least 60 km depth. Using all available tilt, sea level, and seismic data, the tilt reversal is interpreted as due to an episodic reverse slip of about 80 cm magnitude on the plate boundary between about 70 km and 20 km depth, downdip from the main seismogenic zone, which remains locked. This event causes an increase of stress on the locked main thrust zone. It is speculated that such events may be a regular process at subduction zones, that great plate boundary earthquakes may be more common during their occurrence, and that their onset may be detectable early enough to give warning of an increase in probability for the occurrence of a great earthquake.

  3. Understanding the Hydromechanical Behavior of a Fault Zone From Transient Surface Tilt and Fluid Pressure Observations at Hourly Time Scales

    Science.gov (United States)

    Schuite, Jonathan; Longuevergne, Laurent; Bour, Olivier; Burbey, Thomas J.; Boudin, Frédérick; Lavenant, Nicolas; Davy, Philippe

    2017-12-01

    Flow through reservoirs such as fractured media is powered by head gradients which also generate measurable poroelastic deformation of the rock body. The combined analysis of surface deformation and subsurface pressure provides valuable insights of a reservoir's structure and hydromechanical properties, which are of interest for deep-seated CO2 or nuclear waste storage for instance. Among all surveying tools, surface tiltmeters offer the possibility to grasp hydraulically induced deformations over a broad range of time scales with a remarkable precision. Here we investigate the information content of transient surface tilt generated by the pressurization a kilometer scale subvertical fault zone. Our approach involves the combination of field data and results of a fully coupled poromechanical model. The signature of pressure changes in the fault zone due to pumping cycles is clearly recognizable in field tilt data and we aim to explain the peculiar features that appear in (1) tilt time series alone from a set of four instruments and 2) the ratio of tilt over pressure. We evidence that the shape of tilt measurements on both sides of a fault zone is sensitive to its diffusivity and its elastic modulus. The ratio of tilt over pressure predominantly encompasses information about the system's dynamic behavior and extent of the fault zone and allows separating contributions of flow in the different compartments. Hence, tiltmeters are well suited to characterize hydromechanical processes associated with fault zone hydrogeology at short time scales, where spaceborne surveying methods fail to recognize any deformation signal.

  4. Head Tilt

    Science.gov (United States)

    ... bones in the neck. Children with Klippel-Feil syndrome may have a short, broad neck, low hairline, and very restricted neck movement. Torticollis ... surgery may be necessary. To treat Klippel-Feil syndrome, a specialist may recommend ... to ease head and neck pain. Your pediatrician can refer you to a ...

  5. Single particle and molecular assembly analysis of polyribosomes by single- and double-tilt cryo electron tomography

    Energy Technology Data Exchange (ETDEWEB)

    Myasnikov, Alexander G. [IGBMC (Institute of Genetics and of Molecular and Cellular Biology), Department of Integrative Structural Biology, Centre National de la Recherche Scientifique (CNRS) UMR 7104/ Institut National de la Santé de la Recherche Médicale INSERM U964/ Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch (France); Afonina, Zhanna A. [Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region (Russian Federation); Klaholz, Bruno P., E-mail: klaholz@igbmc.fr [IGBMC (Institute of Genetics and of Molecular and Cellular Biology), Department of Integrative Structural Biology, Centre National de la Recherche Scientifique (CNRS) UMR 7104/ Institut National de la Santé de la Recherche Médicale INSERM U964/ Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch (France)

    2013-03-15

    Cryo electron tomography (cryo-ET) can provide cellular and molecular structural information on various biological samples. However, the detailed interpretation of tomograms reconstructed from single-tilt data tends to suffer from low signal-to-noise ratio and artefacts caused by some systematically missing angular views. While these can be overcome by sub-tomogram averaging, they remain limiting for the analysis of unique structures. Double-tilt ET can improve the tomogram quality by acquiring a second tilt series after an in-plane rotation, but its usage is not widespread yet because it is considered technically demanding and it is rarely used under cryo conditions. Here we show that double-tilt cryo-ET improves the quality of 3D reconstructions so significantly that even single particle analysis can be envisaged despite of the intrinsically low image contrast obtained from frozen-hydrated specimens. This is illustrated by the analysis of eukaryotic polyribosomes in which individual ribosomes were reconstructed using single-tilt, partial and full double-tilt geometries. The improved tomograms favour the faster convergence of iterative sub-tomogram averaging and allow a better 3D classification using multivariate statistical analysis. Our study of single particles and molecular assemblies within polysomes illustrates that the dual-axis approach is particularly useful for cryo applications of ET, both for unique objects and for structures that can be classified and averaged. - Highlights: ► Double-tilt cryo-ET improves 3D reconstructions thus making single particle analysis possible. ► Dual-axis cryo-ET data favour a faster convergence of iterative sub-tomogram averaging. ► Individual ribosomes were reconstructed from single-tilt, partial/ full double-tilt geometries. ► Double-tilt cryo-ET facilitates analysis of larger molecular assemblies such as in cell sections. ► Dual-axis cryo-ET is applicable to unique objects and to structures that can be

  6. Octahedral tilt transitions in the relaxor ferroelectric Na{sub 1/2}Bi{sub 1/2}TiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Kai-Christian, E-mail: meyer@mm.tu-darmstadt.de; Gröting, Melanie; Albe, Karsten

    2015-07-15

    The kinetics of octahedral tilt transitions in the lead-free relaxor material sodium bismuth titanate Na{sub 1/2}Bi{sub 1/2}TiO{sub 3} (NBT) is investigated by electronic structure calculations within density functional theory. Energy barriers for transitions between tetragonal, rhombohedral and orthorhombic tilts in cation configurations with [001]- and [111]-order on the A-sites are determined by nudged elastic band calculations. By tilting entire layers of octahedra simultaneously we find that the activation energy is lower for structures with 001-order compared to such with 111-order. The energetic coupling between differently tilted layers is, however, negligibly small. By introducing a single octahedral defect we create local tilt disorder and find that the deformation energy of the neighboring octahedra is less in a rhombohedral than in a tetragonal structure. By successively increasing the size of clusters of orthorhombic defects in a rhombohedral matrix with 001-order, we determine a critical cluster size of about 40 Å . Thus groups of about ten octahedra can be considered as nuclei for polar nanoregions, which are the cause of the experimentally observed relaxor behavior of NBT. - Graphical abstract: Nine orthorhombic oxygen octahedral tilt defects in a rhombohedral tilt configuration. - Highlights: • Chemical order influences energy barriers of octahedral tilt transitions. • The octahedral deformation energy is lower in rhombohedral phases. • Tilt defect clusters are more likely in rhombohedral structures. • Tilt defect clusters can act as nuclei for polar nanoregions.

  7. Test of an Hypothesis of Magnetization, Tilt and Flow in an Hypabyssal Intrusion, Colombian Andes

    Science.gov (United States)

    Muggleton, S.; MacDonald, W. D.; Estrada, J. J.; Sierra, G. M.

    2002-05-01

    Magnetic remanence in the Miocene Clavijo intrusion in the Cauca Valley, adjacent to the Cordillera Central, plunges steeply northward (MacDonald et al., 1996). Assuming magnetization in a normal magnetic field, the expected remanence direction is approximately I= 10o, D= 000o; the observed remanence is I=84o, D=003o. The discrepancy could be explained by a 74o rotation about a horizontal E-W axis, i.e., about an axis normal to the nearby N-S trending Romeral fault zone. If the intrusion is the shallow feeder of a now-eroded andesitic volcano, then perhaps the paleovertical direction is preserved in flow lineations and provides a test of the tilt/rotation of the remanence. In combination, the steep remanence direction, vertical flow, and the inferred rotation of the volcanic neck lead to the hypothesis of a shallow-plunging southward lineation for this body. Using anisotropy of magnetic susceptibility (AMS) as a proxy for the flow lineation, it is predicted that the K1 (maximum susceptibility) axis in this body plunges gently south. This hypothesis was tested using approximately 50 oriented cores from 5 sites near the west margin of the Clavijo intrusion. The results suggest a NW plunging lineation, inconsistent with the initial hypothesis. However, a relatively consistent flow lineation is suggested by the K1 axes. If this flow axis represents paleovertical, it suggests moderate tilting of the Clavijo body towards the southeast. The results are encouraging enough to suggest that AMS may be useful for determining paleo-vertical in shallow volcanic necks and hypabyssal intrusions, and might ultimately be useful in a tilt-correction for such bodies. Other implications of the results will be discussed. MacDonald, WD, Estrada, JJ, Sierra, GM, Gonzalez, H, 1996, Late Cenozoic tectonics and paleomagnetism of North Cauca Basin intrusions, Colombian Andes: Dual rotation modes: Tectonophysics, v 261, p. 277-289.

  8. Plasma depletion layer: its dependence on solar wind conditions and the Earth dipole tilt

    Directory of Open Access Journals (Sweden)

    Y. L. Wang

    2004-12-01

    Full Text Available The plasma depletion layer (PDL is a layer on the sunward side of the magnetopause with lower plasma density and higher magnetic field compared to their corresponding upstream magnetosheath values. It is believed that the PDL is controlled jointly by conditions in the solar wind plasma and the (IMF. In this study, we extend our former model PDL studies by systematically investigating the dependence of the PDL and the slow mode front on solar wind conditions using global MHD simulations. We first point out the difficulties for the depletion factor method and the plasma β method for defining the outer boundary of the plasma depletion layer. We propose to use the N/B ratio to define the PDL outer boundary, which can give the best description of flux tube depletion. We find a strong dependence of the magnetosheath environment on the solar wind magnetosonic Mach number. A difference between the stagnation point and the magnetopause derived from the open-closed magnetic field boundary is found. We also find a strong and complex dependence of the PDL and the slow mode front on the IMF Bz. A density structure right inside the subsolar magnetopause for higher IMF Bz;might be responsible for some of this dependence. Both the IMF tilt and clock angles are found to have little influence on the magnetosheath and the PDL structures. However, the IMF geometry has a much stronger influence on the slow mode fronts in the magnetosheath. Finally, the Earth dipole tilt is found to play a minor role for the magnetosheath geometry and the PDL along the Sun-Earth line. A complex slow mode front geometry is found for cases with different Earth dipole tilts. Comparisons between our results with those from some former studies are conducted, and consistencies and inconsistencies are found. Key words. Magnetospheric physics (magnetosheath, solar wind-magnetosphere interactions – Space plasma physics (numerical simulation studies

  9. Vibration reduction in a tilting rotor using centrifugal pendulum vibration absorbers

    Science.gov (United States)

    Shi, Chengzhi; Shaw, Steven W.; Parker, Robert G.

    2016-12-01

    This paper investigates vibration reduction in a rigid rotor with tilting, rotational, and translational motions using centrifugal pendulum vibration absorbers (CPVAs). A linearized vibration model is derived for the system consisting of the rotor and multiple sets of absorbers tuned to different orders. Each group of absorbers lies in a given plane perpendicular to the rotor rotation axis. Gyroscopic system modal analysis is applied to derive the steady-state response of the absorbers and the rotor to external, rotor-order, periodic forces and torques with frequency mΩ, where Ω is the mean rotor speed and m is the engine order (rotor-order). It is found that an absorber group with tuning order m is effective at reducing the rotor translational, tilting, and rotational vibrations, provided certain conditions are met. When the periodic force and torque are caused by N substructures that are equally spaced around the rotor, the rotor translational and tilting vibrations at order j are addressed by two absorber groups with tuning orders jN±1. In this case, the rotor rotational vibration at order j can be attenuated by an absorber group with tuning order jN. The results show how the response depends on the load amplitudes and order, the rotor speed, and design parameters associated with the sets of absorbers, most importantly, their tuning, mass, and plane of placement. In the ideal case with zero damping and exact tuning of the absorber sets, the vibrations can be eliminated for a range of loads over which the linearized model holds. The response for systems with detuned absorbers is also determined, which is relevant to applications where small detuning is employed due to robustness issues, and to allow for a larger range of operating loads over which the absorbers are effective. The system also exhibits undesirable resonances very close to these tuning conditions, an issue that is difficult to resolve and deserves further investigation.

  10. Stepped defibrillation waveform is substantially more efficient than the 50/50% tilt biphasic.

    Science.gov (United States)

    Seidl, Karlheinz; Denman, Russell A; Moulder, J Christopher; Mouchawar, Gabriel; Stoeppler, Christoph; Becker, Torsten; Weise, Udo; Anskey, Emma J; Burnett, Helen E; Kroll, Mark W

    2006-12-01

    Even with biphasic waveforms, patients with high defibrillation thresholds (DFTs) still are seen; thus, improved defibrillation waveforms may be of clinical utility. The stepped waveform has three parts: the first portion is positive with two capacitors in parallel, the second is positive with the capacitors in series, and the last portion is negative, also with the capacitors in series. The purpose of this study was to assess the clinical utility of improved defibrillation waveforms. We measured the delivered energy DFT in 20 patients in a dual-site study using the stepped waveform and a 50/50% tilt biphasic truncated exponential as the control. All shocks were delivered using an arbitrary waveform defibrillator, which was programmed to mimic two 220-microF capacitors (110 microF in series and 440 microF in parallel). The peak voltage at DFT was reduced in 19 of the 20 patients. The median peak voltage was reduced by 32.0%, from 472 V to 321 V (P voltage and energy were reduced by 25.3% and 20.2%, respectively. On average, the stepped waveform was able to defibrillate as well as the 50/50% tilt biphasic, with 33% more energy. The benefit was more pronounced in patients with either a lower ejection fraction or a superior vena cava coil. The benefit of the stepped waveform had an inverse quadratic correlation with the resistance (r(2) = 0.47), suggesting that the capacitance values chosen for the stepped waveform were close to optimal for a 35-Omega resistance. The stepped waveform reduced the DFT compared to the 50/50% tilt waveform in this preliminary study.

  11. Complexity of cardiovascular rhythms during head-up tilt test by entropy of patterns.

    Science.gov (United States)

    Wejer, Dorota; Graff, Beata; Makowiec, Danuta; Budrejko, Szymon; Struzik, Zbigniew R

    2017-05-01

    The head-up tilt (HUT) test, which provokes transient dynamical alterations in the regulation of cardiovascular system, provides insights into complex organization of this system. Based on signals with heart period intervals (RR-intervals) and/or systolic blood pressure (SBP), differences in the cardiovascular regulation between vasovagal patients (VVS) and the healthy people group (CG) are investigated. Short-term relations among signal data represented symbolically by three-beat patterns allow to qualify and quantify the complexity of the cardiovascular regulation by Shannon entropy. Four types of patterns: permutation, ordinal, deterministic and dynamical, are used, and different resolutions of signal values in the the symbolization are applied in order to verify how entropy of patterns depends on a way in which values of signals are preprocessed. At rest, in the physiologically important signal resolution ranges, independently of the type of patterns used in estimates, the complexity of SBP signals in VVS is different from the complexity found in CG. Entropy of VVS is higher than CG what could be interpreted as substantial presence of noisy ingredients in SBP of VVS. After tilting this relation switches. Entropy of CG occurs significantly higher than VVS for SBP signals. In the case of RR-intervals and large resolutions, the complexity after the tilt becomes reduced when compared to the complexity of RR-intervals at rest for both groups. However, in the case of VVS patients this reduction is significantly stronger than in CG. Our observations about opposite switches in entropy between CG and VVS might support a hypothesis that baroreflex in VVS affects stronger the heart rate because of the inefficient regulation (possibly impaired local vascular tone alternations) of the blood pressure.

  12. Differences between Outdoor and Indoor Sound Levels for Open, Tilted, and Closed Windows.

    Science.gov (United States)

    Locher, Barbara; Piquerez, André; Habermacher, Manuel; Ragettli, Martina; Röösli, Martin; Brink, Mark; Cajochen, Christian; Vienneau, Danielle; Foraster, Maria; Müller, Uwe; Wunderli, Jean Marc

    2018-01-18

    Noise exposure prediction models for health effect studies normally estimate free field exposure levels outside. However, to assess the noise exposure inside dwellings, an estimate of indoor sound levels is necessary. To date, little field data is available about the difference between indoor and outdoor noise levels and factors affecting the damping of outside noise. This is a major cause of uncertainty in indoor noise exposure prediction and may lead to exposure misclassification in health assessments. This study aims to determine sound level differences between the indoors and the outdoors for different window positions and how this sound damping is related to building characteristics. For this purpose, measurements were carried out at home in a sample of 102 Swiss residents exposed to road traffic noise. Sound pressure level recordings were performed outdoors and indoors, in the living room and in the bedroom. Three scenarios-of open, tilted, and closed windows-were recorded for three minutes each. For each situation, data on additional parameters such as the orientation towards the source, floor, and room, as well as sound insulation characteristics were collected. On that basis, linear regression models were established. The median outdoor-indoor sound level differences were of 10 dB(A) for open, 16 dB(A) for tilted, and 28 dB(A) for closed windows. For open and tilted windows, the most relevant parameters affecting the outdoor-indoor differences were the position of the window, the type and volume of the room, and the age of the building. For closed windows, the relevant parameters were the sound level outside, the material of the window frame, the existence of window gaskets, and the number of windows.

  13. The distribution of tilt angles in newly born NSs: role of interior viscosity and magnetic field

    Science.gov (United States)

    Dall'Osso, Simone; Perna, Rosalba

    2017-12-01

    We study how the viscosity of neutron star (NS) matter affects the distribution of tilt angles (χ) between the spin and magnetic axes in young pulsars. Under the hypothesis that the NS shape is determined by the magnetically induced deformation, and that the toroidal component of the internal magnetic field exceeds the poloidal one, we show that the dissipation of precessional motions by bulk viscosity can naturally produce a bi-modal distribution of tilt angles, as observed in radio/γ-ray pulsars, with a low probability of achieving χ ˜ (20°-70°) if the interior B-field is ˜(1011-1015) G and the birth spin period is ˜10-300 ms. As a corollary of the model, the idea that the NS shape is solely determined by the poloidal magnetic field, or by the centrifugal deformation of the crust, is found to be inconsistent with the tilt angle distribution in young pulsars. When applied to the Crab pulsar, with χ ˜ 45°-70° and birth spin ≳20 ms, our model implies that: (I) the magnetically induced ellipticity is ɛB ≳ 3 × 10-6; and (II) the measured positive\\dot{χ } ˜ 3.6 × 10^{-12} rad s-1 requires an additional viscous process, acting on a time-scale ≲104 yr. We interpret the latter as crust-core coupling via mutual friction in the superfluid NS interior. One critical implication of our model is a gravitational wave signal at (twice) the spin frequency of the NS. For ɛB ˜ 10-6, this could be detectable by Advanced LIGO/Virgo operating at design sensitivity.

  14. Band Gap Tuning via Lattice Contraction and Octahedral Tilting in Perovskite Materials for Photovoltaics

    International Nuclear Information System (INIS)

    Prasanna, Rohit; Gold-Parker, Aryeh; Leijtens, Tomas; Conings, Bert

    2017-01-01

    Tin and lead iodide perovskite semiconductors of the composition AMX_3, where M is a metal and X is a halide, are leading candidates for high efficiency low cost tandem photovoltaics, in part because they have band gaps that can be tuned over a wide range by compositional substitution. We experimentally identify two competing mechanisms through which the A-site cation influences the band gap of 3D metal halide perovskites. Using a smaller A-site cation can distort the perovskite lattice in two distinct ways: by tilting the MX_6 octahedra or by simply contracting the lattice isotropically. The former effect tends to raise the band gap, while the latter tends to decrease it. Lead iodide perovskites show an increase in band gap upon partial substitution of the larger formamidinium with the smaller cesium, due to octahedral tilting. Perovskites based on tin, which is slightly smaller than lead, show the opposite trend: they show no octahedral tilting upon Cs-substitution but only a contraction of the lattice, leading to progressive reduction of the band gap. We outline a strategy to systematically tune the band gap and valence and conduction band positions of metal halide perovskites through control of the cation composition. Using this strategy, we demonstrate solar cells that harvest light in the infrared up to 1040 nm, reaching a stabilized power conversion efficiency of 17.8%, showing promise for improvements of the bottom cell of all-perovskite tandem solar cells. In conclusion, the mechanisms of cation-based band gap tuning we describe are broadly applicable to 3D metal halide perovskites and will be useful in further development of perovskite semiconductors for optoelectronic applications.

  15. Band Gap Tuning via Lattice Contraction and Octahedral Tilting in Perovskite Materials for Photovoltaics.

    Science.gov (United States)

    Prasanna, Rohit; Gold-Parker, Aryeh; Leijtens, Tomas; Conings, Bert; Babayigit, Aslihan; Boyen, Hans-Gerd; Toney, Michael F; McGehee, Michael D

    2017-08-16

    Tin and lead iodide perovskite semiconductors of the composition AMX 3 , where M is a metal and X is a halide, are leading candidates for high efficiency low cost tandem photovoltaics, in part because they have band gaps that can be tuned over a wide range by compositional substitution. We experimentally identify two competing mechanisms through which the A-site cation influences the band gap of 3D metal halide perovskites. Using a smaller A-site cation can distort the perovskite lattice in two distinct ways: by tilting the MX 6 octahedra or by simply contracting the lattice isotropically. The former effect tends to raise the band gap, while the latter tends to decrease it. Lead iodide perovskites show an increase in band gap upon partial substitution of the larger formamidinium with the smaller cesium, due to octahedral tilting. Perovskites based on tin, which is slightly smaller than lead, show the opposite trend: they show no octahedral tilting upon Cs-substitution but only a contraction of the lattice, leading to progressive reduction of the band gap. We outline a strategy to systematically tune the band gap and valence and conduction band positions of metal halide perovskites through control of the cation composition. Using this strategy, we demonstrate solar cells that harvest light in the infrared up to 1040 nm, reaching a stabilized power conversion efficiency of 17.8%, showing promise for improvements of the bottom cell of all-perovskite tandem solar cells. The mechanisms of cation-based band gap tuning we describe are broadly applicable to 3D metal halide perovskites and will be useful in further development of perovskite semiconductors for optoelectronic applications.

  16. Tilted cone-beam reconstruction with row-wise fan-to-parallel rebinning

    International Nuclear Information System (INIS)

    Hsieh Jiang; Tang Xiangyang

    2006-01-01

    Reconstruction algorithms for cone-beam CT have been the focus of many studies. Several exact and approximate reconstruction algorithms were proposed for step-and-shoot and helical scanning trajectories to combat cone-beam related artefacts. In this paper, we present a new closed-form cone-beam reconstruction formula for tilted gantry data acquisition. Although several algorithms were proposed in the past to combat errors induced by the gantry tilt, none of the algorithms addresses the scenario in which the cone-beam geometry is first rebinned to a set of parallel beams prior to the filtered backprojection. We show that the image quality advantages of the rebinned parallel-beam reconstruction are significant, which makes the development of such an algorithm necessary. Because of the rebinning process, the reconstruction algorithm becomes more complex and the amount of iso-centre adjustment depends not only on the projection and tilt angles, but also on the reconstructed pixel location. In this paper, we first demonstrate the advantages of the row-wise fan-to-parallel rebinning and derive a closed-form solution for the reconstruction algorithm for the step-and-shoot and constant-pitch helical scans. The proposed algorithm requires the 'warping' of the reconstruction matrix on a view-by-view basis prior to the backprojection step. We further extend the algorithm to the variable-pitch helical scans in which the patient table travels at non-constant speeds. The algorithm was tested extensively on both the 16- and 64-slice CT scanners. The efficacy of the algorithm is clearly demonstrated by multiple experiments

  17. Low-Frequency Otolith Function in Microgravity: A Re-Evaluation of the Otolith Tilt-Translation Reinterpretation (OTTR) Hypothesis

    Science.gov (United States)

    Moore, Steven T.; Cohen, Bernard; Clement, Gilles; Raphan, Theodore

    1999-01-01

    On Earth, the low-frequency afferent signal from the otoliths encodes head tilt with respect to the gravitational vertical, and the higher frequency components reflect both tilt and linear acceleration of the head. In microgravity, static tilt of the head does not influence otolith output, and the relationship between sensory input from the vestibular organs, and the visual, proprioceptive and somatosensory systems, would be disrupted. Several researchers have proposed that in 0-g this conflict may induce a reinterpretation of all otolith signals by the brain to encode only linear translation (otolith tilt-translation reinterpretation or OTTR). Ocular counter-rolling (OCR) is a low-frequency otolith-mediated reflex, which generates compensatory torsional eye movements (rotation about the visual axis) towards the spatial vertical during static roll tilt with a gain of approximately 10%. Transient linear acceleration and off-axis centrifugation at a constant angular velocity can also generate OCR. According to the OTTR hypothesis, OCR should be reduced in microgravity, and immediately upon return from a 0-g environment. Results to date have been inconclusive. OCR was reduced following the 10 day Spacelab-1 mission in response to leftward roll tilts (28-56% in 3 subjects and unchanged in one subject), and sinusoidal linear oscillations at 0.4 and 0.8 Hz. OCR gain declined 70% in four monkeys following a 14 day COSMOS mission. Following a 30 day MIR mission OCR gain decreased in one astronaut, but increased in two others following a 180 day mission. We have studied the affect of microgravity on low-frequency otolith function as part of a larger study of the interaction of vision and the vestibular system. This experiment (E-047) involved off-axis centrifugation of payload crewmembers and flew aboard the recent Neurolab mission (STS 90). Presented below are preliminary results focusing on perception and the OCR response during both centrifugation and static tilt.

  18. Effectiveness of chest compression feedback during cardiopulmonary resuscitation in lateral tilted and semirecumbent positions: a randomised controlled simulation study.

    Science.gov (United States)

    Song, Y; Oh, J; Chee, Y; Cho, Y; Lee, S; Lim, T H

    2015-11-01

    Feedback devices have been shown to improve the quality of chest compression during cardiopulmonary resuscitation for patients in the supine position, but no studies have reported the effects of feedback devices on chest compression when the chest is tilted. Basic life support-trained providers were randomly assigned to administer chest compressions to a manikin in the supine, 30° left lateral tilt and 30° semirecumbent positions, with or without the aid of a feedback device incorporated into a smartphone. Thirty-six participants were studied. The feedback device did not affect the quality of chest compressions in the supine position, but improved aspects of performance in the tilted positions. In the lateral tilted position, the median (IQR [range]) chest compression rate was 99 (99-100 [96-117]) compressions.min(-1) with and 115 (95-128 [77-164]) compressions.min(-1) without feedback (p = 0.05), and the proportion of compressions of correct depth was 55 (0-96 [0-100])% with and 1 (0-30 [0-100])% without feedback (p = 0.03). In the semirecumbent position, the proportion of compressions of correct depth was 21 (0-87 [0-100])% with and 1 (0-26 [0-100])% without feedback (p = 0.05). Female participants applied chest compressions at a more accurate rate using the feedback device in the lateral tilted position but were unable to increase the chest compression depth, whereas male participants were able to increase the force of chest compression using the feedback device in the lateral tilted and semirecumbent positions. We conclude that a feedback device improves the application of chest compressions during simulated cardiopulmonary resuscitation when the chest is tilted. © 2015 The Association of Anaesthetists of Great Britain and Ireland.

  19. Experiment Design for Complex VTOL Aircraft with Distributed Propulsion and Tilt Wing

    Science.gov (United States)

    Murphy, Patrick C.; Landman, Drew

    2015-01-01

    Selected experimental results from a wind tunnel study of a subscale VTOL concept with distributed propulsion and tilt lifting surfaces are presented. The vehicle complexity and automated test facility were ideal for use with a randomized designed experiment. Design of Experiments and Response Surface Methods were invoked to produce run efficient, statistically rigorous regression models with minimized prediction error. Static tests were conducted at the NASA Langley 12-Foot Low-Speed Tunnel to model all six aerodynamic coefficients over a large flight envelope. This work supports investigations at NASA Langley in developing advanced configurations, simulations, and advanced control systems.

  20. STATIC SPINAL DEFORMITY SECONDARY TO PELVIC TILT IN CHILDREN AND ADOLESCENTS: DIAGNOSTICS AND METHODS OF CORRECTION

    Directory of Open Access Journals (Sweden)

    A. A. Gaiduk

    2010-01-01

    Full Text Available For the purpose of the diagnostics of spinal deformity 2,300 children and adolescents were observed by computer optical topography, tilts of the pelvis were identified in 800 of them. As a result of the evaluation of the initial state of the spine and pelvis, performed by computer optical topography diagnostics 5 types of static deformations of spine and pelvis were defined. The criteria for evaluating distortions of the pelvis, frontal deformation and inclination of spine axis were described. Instrumental study with computer optical topography diagnostics in conjunction with clinical examination reveals various kinds of disturbances of posture, feet condition and functional biomechanical changes in the pelvic region.

  1. Could lateral tilt mattresses be the answer to pressure ulcer prevention and management?

    Science.gov (United States)

    Hampton, Sylvie

    2017-03-01

    Pressure ulcers have been part of illness for thousands of years and are not reducing in number. Traditionally, since the Crimean War, patients have been ritually repositioned every 2 hours, regardless of the individual need. Pressure ulcers occur mainly on bony prominences, and so it makes sense to reposition into the 30 degree tilt, off of bony prominences. Nevertheless, this still takes time in order to reposition on a regular basis. It is time to look at automatic repositioning, reducing nursing time, increasing patient comfort and releasing carers to provide more social support to the patients.

  2. Effect of dust on tilted electrostatic resistive instability in a Hall thruster

    Science.gov (United States)

    Tyagi, Jasvendra; Singh, Sukhmander; Malik, Hitendra K.

    2018-03-01

    Effect of negatively charged dust on resistive instability corresponding to the electrostatic wave is investigated in a Hall thruster plasma when this purely azimuthal wave is tilted and strong axial component of wave vector is developed. Analytical calculations are done to obtain the relevant dispersion equation, which is solved numerically to investigate the growth rate of the instability. The magnitude of the growth rate in the plasma having dust particles is found to be much smaller than the case of pure plasma. However, the instability grows faster for the increasing dust density and the higher charge on the dust particles. The higher magnetic field is also found to support the instability.

  3. Dynamic Coefficients of a Tilting Pad With Active Lubrication: Comparison Between Theoretical and Experimental Results

    DEFF Research Database (Denmark)

    Cerda Varela, Alejandro Javier; Santos, Ilmar

    2015-01-01

    This paper deals with the validation of the mathematical model for predicting the equivalent stiffness and damping of an active tilting-pad bearing. The active bearing design includes an injection nozzle in the pad and a hydraulic supply system featuring a servovalve, which enables to modify the ....... The results provide an overview about the feasibility of modifying the bearing impedance by means of the active lubrication system, both in open-loop (fixed control signal), or closed-loop, as a function of the journal position and proportional derivative (PD) controller gains....

  4. A mechanical model of biomimetic adhesive pads with tilted and hierarchical structures.

    Science.gov (United States)

    Schargott, M

    2009-06-01

    A 3D model for hierarchical biomimetic adhesive pads is constructed. It is based on the main principles of the adhesive pads of the Tokay gecko and consists of hierarchical layers of vertical or tilted beams, where each layer is constructed in such a way that no cohesion between adjacent beams can occur. The elastic and adhesive properties are calculated analytically and numerically. For the adhesive contact on stochastically rough surfaces, the maximum adhesion force increases with increasing number of hierarchical layers. Additional calculations show that the adhesion force also depends on the height spectrum of the rough surface.

  5. A mechanical model of biomimetic adhesive pads with tilted and hierarchical structures

    Energy Technology Data Exchange (ETDEWEB)

    Schargott, M [Institute of Mechanics, Technische Universitaet Berlin, Strd 17 Juni 135, 10623 Berlin (Germany)], E-mail: martin.schargott@tu-berlin.de

    2009-06-01

    A 3D model for hierarchical biomimetic adhesive pads is constructed. It is based on the main principles of the adhesive pads of the Tokay gecko and consists of hierarchical layers of vertical or tilted beams, where each layer is constructed in such a way that no cohesion between adjacent beams can occur. The elastic and adhesive properties are calculated analytically and numerically. For the adhesive contact on stochastically rough surfaces, the maximum adhesion force increases with increasing number of hierarchical layers. Additional calculations show that the adhesion force also depends on the height spectrum of the rough surface.

  6. Plasmon-enhanced refractometry using silver nanowire coatings on tilted fibre Bragg gratings.

    Science.gov (United States)

    Bialiayeu, A; Bottomley, A; Prezgot, D; Ianoul, A; Albert, J

    2012-11-09

    A novel technique for increasing the sensitivity of tilted fibre Bragg grating (TFBG) based refractometers is presented. The TFBG sensor was coated with chemically synthesized silver nanowires ~100 nm in diameter and several micrometres in length. A 3.5-fold increase in sensor sensitivity was obtained relative to the uncoated TFBG sensor. This increase is associated with the excitation of surface plasmons by orthogonally polarized fibre cladding modes at wavelengths near 1.5 μm. Refractometric information is extracted from the sensor via the strong polarization dependence of the grating resonances using a Jones matrix analysis of the transmission spectrum of the fibre.

  7. Dual-frequency terahertz emission from splitting filaments induced by lens tilting in air

    International Nuclear Information System (INIS)

    Zhang, Zhelin; Chen, Yanping; Yang, Liu; Yuan, Xiaohui; Liu, Feng; Chen, Min; Xu, Jianqiu; Zhang, Jie; Sheng, Zhengming

    2014-01-01

    Dual-frequency terahertz radiation from air-plasma filaments produced with two-color lasers in air has been demonstrated experimentally. When a focusing lens is tilted for a few degrees, it is shown that the laser filament evolves from a single one to two sub-filaments. Two independent terahertz sources emitted from the sub-filaments with different frequencies and polarizations are identified, where the frequency of terahertz waves from the trailing sub-filament is higher than that from the leading sub-filament.

  8. Tilting-Pad Journal Bearings with Active Lubrication Applied as Calibrated Shakers: Theory and Experiment

    DEFF Research Database (Denmark)

    Cerda Varela, Alejandro Javier; Santos, Ilmar

    2014-01-01

    In recent years, a continuous research effort has transformed the conventional tilting-pad journal bearing into a mechatronic machine element. The addition of electromechanical elements provides the possibility of generating controllable forces over the rotor as a function of a suitable control...... directly into the bearing clearance. The injected flow is controlled by means of a servovalve. The theoretical model includes the dynamics of servovalves and pipelines using a lumped parameter approach, whereas the coupling between the hydraulic system and the bearing oil film is modeled using a modified...

  9. A comparison of optimal and noise-abatement trajectories of a tilt-rotor aircraft

    Science.gov (United States)

    Schmitz, F. H.; Stepniewski, W. Z.; Gibs, J.; Hinterkeuser, W. Z.

    1972-01-01

    The potential benefits of flight path control to optimize performance and/or reduce the noise of a tilt-rotor aircraft operating in the takeoff and landing phases of flight are investigated. A theoretical performance-acoustic model is developed and then mathematically flown to yield representative takeoff and landing profiles. Minimum-time and minimum-fuel trajectories are compared to proposed noise-abatement profiles to assess the reductions in annoyance possible through flight path control. Significant reductions are feasible if a nearly vertical-takeoff flight profile is flown near the landing site; however, the time expended and fuel consumed increase.

  10. Tilt teste no diagnóstico diferencial da "epilepsia" resistente ao tratamento

    OpenAIRE

    Castro,Renata Rodrigues Teixeira de; Nóbrega,Antonio Claudio Lucas da

    2006-01-01

    A epilepsia é uma das causas mais freqüentes de distúrbios neurológicos em adultos jovens. Relatamos um caso em que uma paciente conviveu durante doze anos com o diagnóstico de epilepsia resistente ao tratamento, quando, na verdade, a causa de seus sintomas pôde ser encontrada com a realização do teste de inclinação (tilt teste). O cardiologista deve estar alerta para o possível diagnóstico de síncope neurocardiogênica em pacientes previamente diagnosticados como portadores de epilepsia, espe...

  11. Equilibrium points of the tilted perfect fluid Bianchi VIh state space

    Science.gov (United States)

    Apostolopoulos, Pantelis S.

    2005-05-01

    We present the full set of evolution equations for the spatially homogeneous cosmologies of type VIh filled with a tilted perfect fluid and we provide the corresponding equilibrium points of the resulting dynamical state space. It is found that only when the group parameter satisfies h > -1 a self-similar solution exists. In particular we show that for h > -{1/9} there exists a self-similar equilibrium point provided that γ ∈ ({2(3+sqrt{-h})/5+3sqrt{-h}},{3/2}) whereas for h VIh.

  12. Tilt and shift mode stability in a spheromak with a flux core

    Energy Technology Data Exchange (ETDEWEB)

    Finn, J.M.; Jardin, S.C.

    1984-07-01

    The stability of spheromak equilibria with a flux core, or reversal coil, is studied by means of an ideal MHD code. Results depend critically upon whether the flux hole region (the current free area just inside the separatrix) is treated as perfectly conducting plasma or as vacuum. This indicates that the tilt and shift modes persist as resistive instabilities if they are stable in ideal MHD. Specifically, for nonoptimally shaped equilibria, the flux core must nearly touch the current channel if the flux hole is vacuum, whereas the core may be slightly outside the separatrix if the flux hole has conducting plasma. A larger margin exists for optimally shaped equilibria.

  13. Electroluminescence Analysis by Tilt Polish Technique of InP-Based Semiconductor Lasers

    Science.gov (United States)

    Ichikawa, Hiroyuki; Sasaki, Kouichi; Hamada, Kotaro; Yamaguchi, Akira

    2010-03-01

    We developed an effective electroluminescence (EL) analysis method to specify the degraded region of InP-based semiconductor lasers. The EL analysis method is one of the most important methods for failure analysis. However, EL observation was difficult because opaque electrodes surround an active layer. A portion of each electrode had to be left intact for wiring to inject the current. Thus, we developed a partial polish technique for the bottom electrode. Tilt polish equipment with a rotating table was introduced; a flat polished surface and a sufficiently wide remaining portion of the bottom electrode were obtained. As a result, clear EL from the back surface of the laser was observed.

  14. Control of octahedral tilts and magnetic properties of perovskite oxide heterostructures by substrate symmetry.

    Science.gov (United States)

    He, Jun; Borisevich, Albina; Kalinin, Sergei V; Pennycook, Stephen J; Pantelides, Sokrates T

    2010-11-26

    Perovskite transition-metal oxides are networks of corner-sharing octahedra whose tilts and distortions are known to affect their electronic and magnetic properties. We report calculations on a model interfacial structure which avoids chemical influences and show that the symmetry mismatch imposes an interfacial layer with distortion modes that do not exist in either bulk material, creating new interface properties driven by symmetry alone. Depending on the resistance of the octahedra to deformation, the interface layer can be as small as one unit cell or extend deep into the thin film.

  15. Otolith tilt-translation reinterpretation following prolonged weightlessness - Implications for preflight training

    Science.gov (United States)

    Parker, D. E.; Reschke, M. F.; Arrott, A. P.; Homick, J. L.; Lichtenberg, B. K.

    1985-01-01

    Observations with three astronauts yielded two major findings. First, perceived self-motion during sinusoidal roll differed immediately postflight from preflight. Between 70 and 150 min after landing, roll was perceived primarily as linear translation. Secondly, more horizontal eye movement was elicited by roll simulation immediately postflight relative to both preflight and later postflight observations. These results support an 'otolith tilt-translation reinterpretation' hypothesis, which has clear implications for understanding astronaut reports of space motion sickness during the early period of orbital flight. A proposal for 'prophylactic adaptation training' which may provide preflight adaptation to weightlessness, derives from this reearch.

  16. A mechanical model of biomimetic adhesive pads with tilted and hierarchical structures

    International Nuclear Information System (INIS)

    Schargott, M

    2009-01-01

    A 3D model for hierarchical biomimetic adhesive pads is constructed. It is based on the main principles of the adhesive pads of the Tokay gecko and consists of hierarchical layers of vertical or tilted beams, where each layer is constructed in such a way that no cohesion between adjacent beams can occur. The elastic and adhesive properties are calculated analytically and numerically. For the adhesive contact on stochastically rough surfaces, the maximum adhesion force increases with increasing number of hierarchical layers. Additional calculations show that the adhesion force also depends on the height spectrum of the rough surface

  17. Application of engineering models to predict wake deflection due to a tilted wind turbine

    DEFF Research Database (Denmark)

    Guntur, Srinivas; Troldborg, Niels; Gaunaa, Mac

    2012-01-01

    such a mechanism introduces control complications due to changing wind directions. Deflecting the wake in the vertical direction using tilt, on the other hand, overcomes this challenge. In this paper, the feasibility of steering wake is explored in a simple uniform inflow case. This is done by trying to model......It is a known fact that the power produced by wind turbines operating inside an array decreases due to the wake effects of the upstream turbines. It has been proposed previously to use the yaw mechanism as a potential means to steer the upstream wake away from downstream turbines, however...

  18. Quality analysis of crustal tilt and strain observations in China's earthquakes in 2014

    Directory of Open Access Journals (Sweden)

    Zhiyao Chen

    2015-11-01

    Full Text Available This work analyzes the quality of crustal tilt and strain observations during 2014, which were acquired from 269 sets of ground tiltmeters and 212 sets of strainmeters. In terms of data quality, the water tube tiltmeters presented the highest rate of excellent quality, approximately 91%, and the pendulum tiltmeters and ground strainmeters yielded rates of 81% and 78%, respectively. This means that a total of 380 sets of instruments produced high-quality observational data suitable for scientific investigations and analyses.

  19. Control techniques of tilt rotor unmanned aerial vehicle systems: A review

    Directory of Open Access Journals (Sweden)

    Zhong Liu

    2017-02-01

    Full Text Available The tilt rotor unmanned aerial vehicle (TRUAV exhibits special application value due to its unique rotor structure. However, varying dynamics and aerodynamic interference caused by tiltable rotors are great technical challenges and key issues for TRUAV’s high-powered flight controls, which have attracted the attention of many researchers. This paper outlines the concept of TRUAV and some typical TRUAV platforms while focusing on control techniques. TRUAV structural features, dynamics modeling, and flight control methods are discussed, and major challenges and corresponding developmental tendencies associated with TRUAV flight control are summarized.

  20. Frequency Response Analysis of an Actively Lubricated Rotor/Tilting-Pad Bearing System

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar

    2004-01-01

    In the present paper, the dynamic response of a rotor supported by an active lubricated tilting-pad bearing is investigated in the frequency domain. The theoretical part of the investigation is based on a mathematical model obtained by means of rigid body dynamics. The oil film forces are inserted......-pad bearing. By applying a simple proportional controller, it is possible to reach 30% reduction of the resonance peak associated with the first rigid body mode shape of the system. One of the most important consequences of such a vibration reduction in rotating machines is the feasibility of increasing...